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Sample records for classifying erosion risks

  1. Mapping soil erosion risk in Serra de Grândola (Portugal)

    Science.gov (United States)

    Neto Paixão, H. M.; Granja Martins, F. M.; Zavala, L. M.; Jordán, A.; Bellinfante, N.

    2012-04-01

    Geomorphological processes can pose environmental risks to people and economical activities. Information and a better knowledge of the genesis of these processes is important for environmental planning, since it allows to model, quantify and classify risks, what can mitigate the threats. The objective of this research is to assess the soil erosion risk in Serra de Grândola, which is a north-south oriented mountain ridge with an altitude of 383 m, located in southwest of Alentejo (southern Portugal). The study area is 675 km2, including the councils of Grândola, Santiago do Cacém and Sines. The process for mapping of erosive status was based on the guidelines for measuring and mapping the processes of erosion of coastal areas of the Mediterranean proposed by PAP/RAC (1997), developed and later modified by other authors in different areas. This method is based on the application of a geographic information system that integrates different types of spatial information inserted into a digital terrain model and in their derivative models. Erosive status are classified using information from soil erodibility, slope, land use and vegetation cover. The rainfall erosivity map was obtained using the modified Fournier index, calculated from the mean monthly rainfall, as recorded in 30 meteorological stations with influence in the study area. Finally, the soil erosion risk map was designed by ovelaying the erosive status map and the rainfall erosivity map.

  2. Development of erosion risk map using fuzzy logic approach

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    Fauzi Manyuk

    2017-01-01

    Full Text Available Erosion-hazard assessment is an important aspect in the management of a river basin such as Siak River Basin, Riau Province, Indonesia. This study presents an application of fuzzy logic approach to develop erosion risk map based on geographic information system. Fuzzy logic is a computing approach based on “degrees of truth” rather than the usual “true or false” (1 or 0 Boolean logic on which the modern computer is based. The results of the erosion risk map were verified by using field measurements. The verification result shows that the parameter of soil-erodibility (K indicates a good agreement with field measurement data. The classification of soil-erodibility (K as the result of validation were: very low (0.0–0.1, medium (0.21-0.32, high (0.44-0.55 and very high (0.56-0.64. The results obtained from this study show that the erosion risk map of Siak River Basin were dominantly classified as medium level which cover about 68.54%. The other classifications were high and very low erosion level which cover about 28.84% and 2.61% respectively.

  3. Assessment of soil erosion risk in Komering watershed, South Sumatera, using SWAT model

    Science.gov (United States)

    Salsabilla, A.; Kusratmoko, E.

    2017-07-01

    Changes in land use watershed led to environmental degradation. Estimated loss of soil erosion is often difficult due to some factors such as topography, land use, climate and human activities. This study aims to predict soil erosion hazard and sediment yield using the Soil and Water Assessment Tools (SWAT) hydrological model. The SWAT was chosen because it can simulate the model with limited data. The study area is Komering watershed (806,001 Ha) in South Sumatera Province. There are two factors land management intervention: 1) land with agriculture, and 2) land with cultivation. These factors selected in accordance with the regulations of spatial plan area. Application of the SWAT demonstrated that the model can predict surface runoff, soil erosion loss and sediment yield. The erosion risk for each watershed can be classified and predicted its changes based on the scenarios which arranged. In this paper, we also discussed the relationship between the distribution of erosion risk and watershed's characteristics in a spatial perspective.

  4. The comparison of various approach to evaluation erosion risks and design control erosion measures

    Science.gov (United States)

    Kapicka, Jiri

    2015-04-01

    In the present is in the Czech Republic one methodology how to compute and compare erosion risks. This methodology contain also method to design erosion control measures. The base of this methodology is Universal Soil Loss Equation (USLE) and their result long-term average annual rate of erosion (G). This methodology is used for landscape planners. Data and statistics from database of erosion events in the Czech Republic shows that many troubles and damages are from local episodes of erosion events. An extent of these events and theirs impact are conditional to local precipitation events, current plant phase and soil conditions. These erosion events can do troubles and damages on agriculture land, municipally property and hydro components and even in a location is from point of view long-term average annual rate of erosion in good conditions. Other way how to compute and compare erosion risks is episodes approach. In this paper is presented the compare of various approach to compute erosion risks. The comparison was computed to locality from database of erosion events on agricultural land in the Czech Republic where have been records two erosion events. The study area is a simple agriculture land without any barriers that can have high influence to water flow and soil sediment transport. The computation of erosion risks (for all methodology) was based on laboratory analysis of soil samples which was sampled on study area. Results of the methodology USLE, MUSLE and results from mathematical model Erosion 3D have been compared. Variances of the results in space distribution of the places with highest soil erosion where compared and discussed. Other part presents variances of design control erosion measures where their design was done on based different methodology. The results shows variance of computed erosion risks which was done by different methodology. These variances can start discussion about different approach how compute and evaluate erosion risks in areas

  5. Estimating surface soil erosion losses and mapping erosion risk for Yusufeli micro-catchment (Artvin

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    Mustafa Tüfekçioğlu

    2016-10-01

    Full Text Available Sheet erosion, one of the most important types of water erosion, takes place on the top soil as tiny soil layer movement that affects lake and stream ecosystem. This type of erosion is very important because the productive soil layer on the top soil can be lost in a very short period of time. The goal of this study was to quantify the amount of surface (sheet and rill soil erosion, and to identify areas under high erosion risk within the study area at Yusufeli province in Artvin by using RUSLE erosion methodology. As a result of the study it was found that the average annual potential soil loss by surface erosion was 3.6 ton ha-1yr-1. Additionally, the maps produced and conclusions reached by the study revealed that the areas of high erosion risk were identified spatially and measures to control erosion on some of these high risk areas can be possible with appropriate erosion control techniques.

  6. Estimation of soil erosion risk within an important agricultural sub-watershed in Bursa, Turkey, in relation to rapid urbanization.

    Science.gov (United States)

    Ozsoy, Gokhan; Aksoy, Ertugrul

    2015-07-01

    This paper integrates the Revised Universal Soil Loss Equation (RUSLE) with a GIS model to investigate the spatial distribution of annual soil loss and identify areas of soil erosion risk in the Uluabat sub-watershed, an important agricultural site in Bursa Province, Turkey. The total soil loss from water erosion was 473,274 Mg year(-1). Accordingly, 60.3% of the surveyed area was classified into a very low erosion risk class while 25.7% was found to be in high and severe erosion risk classes. Soil loss had a close relationship with land use and topography. The most severe erosion risk typically occurs on ridges and steep slopes where agriculture, degraded forest, and shrubs are the main land uses and cover types. Another goal of this study was to use GIS to reveal the multi-year urbanization status caused by rapid urbanization that constitutes another soil erosion risk in this area. Urbanization has increased by 57.7% and the most areal change was determined in class I lands at a rate of 80% over 25 years. Urbanization was identified as one of the causes of excessive soil loss in the study area.

  7. Risk behaviors related to eating disorders in adolescents and its association with dental erosion

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    Daniella Fagundes SOUTO

    Full Text Available Abstract Introduction The overvaluation of thinness as a standard of beauty has contributed to the development of eating disorders and has mainly affected adolescents and young adults. Objective To evaluate the prevalence of risk behaviors for eating disorders and their association with dental erosion in adolescents. Material and method This is a cross-sectional observational epidemiological study. The sample consisted of 278 adolescents aged 12 to 19 years, enrolled in a State School in Campinas - SP. Two questionnaires were used for the data collection on eating disorders: Bulimic Investigatory Test of Edinburgh and Eating Attitudes Test -26. The presence of erosion was evaluated by calibrated examiners. Result The mean age of the sample was 14.8 years. The prevalence of mean risk for bulimia in the sample was 43.2% (95% CI: 37.3%-49.0% and the prevalence of adolescents with a probability of developing bulimia was 53.2% (95% CI: 47.4%-59.1%. Of the total, 11.9% (95% CI: 8.1%-15.7% showed results suggestive of anorexia. Among women, 66.9% were classified as probability developing bulimia, whereas in men the prevalence was 39.0%. As for dental erosion, only 1.1% of the sample presented erosion. Conclusion The study pointed to large number of adolescents with risk behaviors for eating disorders but no association was found with dental erosion due to low prevalence.

  8. The determination of risk areas for muddy floods based on a worst-case erosion modelling

    Science.gov (United States)

    Saathoff, Ulfert; Schindewolf, Marcus; Annika Arévalo, Sarah

    2013-04-01

    Soil erosion and muddy floods are a frequently occurring hazard in the German state of Saxony, because of the topography and the high relief energy together with the high proportion of arable land. Still, the events are rather heterogeneously distributed and we do not know where damage is likely to occur. The goal of this study is to locate hot spots for the risk of muddy floods, with the objective to prevent high economic damage in future. We applied a soil erosion and deposition map of Saxony, calculated with the process based soil erosion model EROSION 3D. This map shows the potential soil erosion and transported sediment for worst case soil conditions and a 10 year rain storm event. Furthermore, a map of the current landuse in the state is used. From the landuse map, we extracted those areas that are especially vulnerable to muddy floods, like residential and industrial areas, infrastructural facilities (e.g. power plants, hospitals) and highways. In combination with the output of the soil erosion model, the amount of sediment, that enters each single landuse entity, is calculated. Based on this data, a state-wide map with classified risks is created. The results are furthermore used to identify the risk of muddy floods for each single municipality in Saxony. The results are evaluated with data of real occurred muddy flood events with documented locations during the period between 2000 and 2010. Additionally, plausibility tests are performed for selected areas (examination of landuse, topography and soil). The results prove to be plausible and most of the documented events can be explained by the modelled risk map. The created map can be used by different institutions like city and traffic planners, to estimate the risk of muddy flood occurrence at specific locations. Furthermore, the risk map can serve insurance companies to evaluate the insurance risk of a building. To make them easily accessible, the risk map will be published online via a web GIS

  9. Mapping Soil Erosion Factors and Potential Erosion Risk for the National Park "Central Balkan"

    Science.gov (United States)

    Ilieva, Diliana; Malinov, Ilia

    2014-05-01

    Soil erosion is widely recognised environmental problem. The report aims at presenting the main results from assessment and mapping of the factors of sheet water erosion and the potential erosion risk on the territory of National Park "Central Balkan". For this purpose, the Universal Soil Loss Equation (USLE) was used for predicting soil loss from erosion. The influence of topography (LS-factor) and soil erodibility (K-factor) was assessed using small-scale topographic and soil maps. Rainfall erosivity (R-factor) was calculated from data of rainfalls with amounts exceeding 9.5 mm from 14 hydro-meteorological stations. The values of the erosion factors (R, K and LS) were presented for the areas of forest, sub-alpine and alpine zones. Using the methods of GIS, maps were plotted presenting the area distribution among the classes of the soil erosion factors and the potential risk in the respective zones. The results can be used for making accurate decisions for soil conservation and sustainable land management in the park.

  10. Water erosion risk prediction in eucalyptus plantations

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    Mayesse Aparecida da Silva

    2014-04-01

    Full Text Available Eucalyptus plantations are normally found in vulnerable ecosystems such as steep slope, soil with low natural fertility and lands that were degraded by agriculture. The objective of this study was to obtain Universal Soil Loss Equation (USLE factors and use them to estimate water erosion risk in regions with eucalyptus planted. The USLE factors were obtained in field plots under natural rainfall in the Rio Doce Basin, MG, Brazil, and the model applied to assess erosion risk using USLE in a Geographic Information System. The study area showed rainfall-runoff erosivity values from 10,721 to 10,642 MJ mm ha-1 h-1 yr-1. Some soils (Latosols had very low erodibility values (2.0 x 10-4 and 1.0 x 10-4t h MJ-1 mm-1, the topographic factor ranged from 0.03 to 10.57 and crop and management factor values obtained for native forest, eucalyptus and planted pasture were 0.09, 0.12 and 0.22, respectively. Water erosion risk estimates for current land use indicated that the areas where should receive more attention were mainly areas with greater topographic factors and those with Cambisols. Planning of forestry activities in this region should consider implementation of other conservation practices beyond those already used, reducing areas with a greater risk of soil erosion and increasing areas with very low risk.

  11. Probabilistic soil erosion modeling using the Erosion Risk Management Tool (ERMIT) after wildfires

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    P. R. Robichaud; W. J. Elliot; J. W. Wagenbrenner

    2011-01-01

    The decision of whether or not to apply post-fire hillslope erosion mitigation treatments, and if so, where these treatments are most needed, is a multi-step process. Land managers must assess the risk of damaging runoff and sediment delivery events occurring on the unrecovered burned hillslope. We developed the Erosion Risk Management Tool (ERMiT) to address this need...

  12. Multivariate erosion risk assessment of lateritic badlands of Birbhum ...

    Indian Academy of Sciences (India)

    Erosion risk; soil erosion; sediment yield; multivariate analysis; GIS. J. Earth Syst. Sci. 121, No. ... ers are threatened by excessive soil loss by water. To reach that goal the ... nacle erosion, bare soil cover, barren waste land, tunnels and ...

  13. RISK LEVEL ANALYSIS ON THE PREVENTIVE EROSION CAPACITY OF BRIDGES

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Deficiency of the Preventive Erosion Capacity (PEC) of a bridge pier is the main factor leading to bridge failures. In this paper, the PEC of bridge piers was analyzed using the stochastic analysis method. The definitions of the reliability and risk level of a bridge pier subjected to water erosion were proposed and a computational model for erosion depth and risk level in was suggested.

  14. Communicating and Visualizing Erosion-associated Risks to Infrastructure

    Science.gov (United States)

    Hewett, Caspar; Simpson, Carolyn; Wainwright, John

    2016-04-01

    Soil erosion is a major problem worldwide, affecting agriculture, the natural environment and urban areas through its impact on flood risk, water quality, loss of nutrient-rich upper soil layers, eutrophication of water bodies, sedimentation of waterways and sediment-related damage to roads, buildings and infrastructure such as water, gas and electricity supply networks. This study focuses on risks to infrastructure associated with erosion and the interventions needed to reduce those risks. Deciding on what interventions to make means understanding better which parts of the landscape are most susceptible to erosion and which measures are most effective in reducing it. Effective ways of communicating mitigation strategies to stakeholders such as farmers, land managers and policy-makers are then essential if interventions are to be implemented. Drawing on the Decision-Support Matrix (DSM) approach which combines a set of hydrological principles with Participatory Action Research (PAR), a decision-support tool for Communicating and Visualizing Erosion-Associated Risks to Infrastructure (CAVERTI) was developed. The participatory component was developed with the Wear Rivers Trust, focusing on a case-study area in the North East of England. The CAVERTI tool brings together process understanding gained from modelling with knowledge and experience of a variety of stakeholders to address directly the problem of sediment transport. Development of the tool was a collaborative venture, ensuring that the problems and solutions presented are easily recognised by practitioners and decision-makers. This recognition, and ease of access via a web-based interface, in turn help to ensure that the tools get used. The web-based tool developed helps to assess, manage and improve understanding of risk from a multi-stakeholder perspective and proposes solutions to problems. We argue that visualization and communication tools co-developed by researchers and stakeholders are the best means

  15. Chapter 4. Predicting post-fire erosion and sedimentation risk on a landscape scale

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    MacDonald, L.H.; Sampson, R.; Brady, D.; Juarros, L.; Martin, Deborah

    2000-01-01

    Historic fire suppression efforts have increased the likelihood of large wildfires in much of the western U.S. Post-fire soil erosion and sedimentation risks are important concerns to resource managers. In this paper we develop and apply procedures to predict post-fire erosion and sedimentation risks on a pixel-, catchment-, and landscape-scale in central and western Colorado.Our model for predicting post-fire surface erosion risk is conceptually similar to the Revised Universal Soil Loss Equation (RUSLE). One key addition is the incorporation of a hydrophobicity risk index (HY-RISK) based on vegetation type, predicted fire severity, and soil texture. Post-fire surface erosion risk was assessed for each 90-m pixel by combining HYRISK, slope, soil erodibility, and a factor representing the likely increase in soil wetness due to removal of the vegetation. Sedimentation risk was a simple function of stream gradient. Composite surface erosion and sedimentation risk indices were calculated and compared across the 72 catchments in the study area.When evaluated on a catchment scale, two-thirds of the catchments had relatively little post-fire erosion risk. Steeper catchments with higher fuel loadings typically had the highest post-fire surface erosion risk. These were generally located along the major north-south mountain chains and, to a lesser extent, in west-central Colorado. Sedimentation risks were usually highest in the eastern part of the study area where a higher proportion of streams had lower gradients. While data to validate the predicted erosion and sedimentation risks are lacking, the results appear reasonable and are consistent with our limited field observations. The models and analytic procedures can be readily adapted to other locations and should provide useful tools for planning and management at both the catchment and landscape scale.

  16. Identification of soil erosion risk areas for conservation planning in different states of India.

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    Sharda, V N; Mandal, Debashis; Ojasvi, P R

    2013-03-01

    Assessment of soil erosion risks, especially in the developing countries, is a challenging task mainly due to non-availability or insufficiency of relevant data. In this paper, the soil erosion risks have been estimated by integrating the spatial data on potential erosion rates and soil loss tolerance limits for conservation planning at state level in India. The erosion risk classes have been prioritized based upon the difference between the prevailing erosion rates and the permissible erosion limits. The analysis revealed that about 50% of total geographical area (TGA) of India, falling in five priority erosion risk classes, requires different intensity of conservation measures though about 91% area suffers from potential erosion rates varying from 40 t ha(-1) yr(-1). Statewise analysis indicated that Andhra Pradesh, Maharashtra and Rajasthan share about 75% of total area under priority Class 1 (6.4 M ha) though they account for only 19.4% of the total area (36.2 M ha) under very severe potential erosion rate category (> 40 t ha(-1)yr(-1)). It was observed that about 75% of total geographical area (TGA) in the states of Bihar, Gujarat, Haryana, Kerala and Punjab does not require any specific soil conservation measure as the potential erosion rates are well within the tolerance limits. The developed methodology can be successfully employed for prioritization of erosion risk areas at watershed, region or country level.

  17. Estimating the Soil Erosion Risk Around Ankara-Bağlum Kösrelik Pond Using CORINE Method

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    Emel YALÇIN

    2016-09-01

    Full Text Available In this study, the Rural Recreation Area of Kösrelik Pond in the Keçiören district of Ankara was studied. The maps of potential and actual soil erosion risk of about 65 ha of the environment surrounding the pond, which was planned as a rural recreation area, were investigated using CORINE methodology. Accordingly, the necessary physical and chemical soil analyses were performed on 10 surface samples and soil samples from 4 profiles additionally opened on the field, and the maps were created by CORINE methodology using GIS technologies. According to the results of the potential soil erosion risk map obtained in this study, no potential erosion risk was found in 10% whereas, low risk of potential erosion was determined in 9%. In addition medium risk of potential erosion was found in 66%, and high risk of potential erosion was found in 15% of the total area. Nevertheless, according to the results of the actual soil erosion risk map, no actual erosion risk was found in 10% whereas, low risk was found in 2%, medium risk was found in 24%. Moreover, high risk of actual erosion was found in 64% of the total area. It has been observed that the natural vegetation within the study area has substantially prevented erosion. The amount of erosion substantially increases due to the destruction of natural vegetation and soil cultivation of agricultural land

  18. Multivariate return periods of sea storms for coastal erosion risk assessment

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    S. Corbella

    2012-08-01

    Full Text Available The erosion of a beach depends on various storm characteristics. Ideally, the risk associated with a storm would be described by a single multivariate return period that is also representative of the erosion risk, i.e. a 100 yr multivariate storm return period would cause a 100 yr erosion return period. Unfortunately, a specific probability level may be associated with numerous combinations of storm characteristics. These combinations, despite having the same multivariate probability, may cause very different erosion outcomes. This paper explores this ambiguity problem in the context of copula based multivariate return periods and using a case study at Durban on the east coast of South Africa. Simulations were used to correlate multivariate return periods of historical events to return periods of estimated storm induced erosion volumes. In addition, the relationship of the most-likely design event (Salvadori et al., 2011 to coastal erosion was investigated. It was found that the multivariate return periods for wave height and duration had the highest correlation to erosion return periods. The most-likely design event was found to be an inadequate design method in its current form. We explore the inclusion of conditions based on the physical realizability of wave events and the use of multivariate linear regression to relate storm parameters to erosion computed from a process based model. Establishing a link between storm statistics and erosion consequences can resolve the ambiguity between multivariate storm return periods and associated erosion return periods.

  19. Prevalence and risk factors of dental erosion in American children.

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    Habib, Mariam; Hottel, Timothy L; Hong, Liang

    2013-01-01

    The purpose of this study was to assess the prevalence and characteristics of dental erosion in children aged 2-4 years old and 12 years old. 243 subjects were recruited from daycare centers, preschools, and grade schools; they received dental examinations assessing their condition of dental erosion, including both depth and area of tooth surface loss on four maxillary incisors. Questionnaires were given to the subjects to obtain socio-demographic, oral health behaviors at home, and access to dental care. Dental erosion was analyzed and risk factors were assessed using Chi-Square and logistic regression analysis. The subjects were 60% Caucasians, 31% Black, 7% Hispanic and others were 2%. 34% of children could not get the dental care they needed within the past 12 months and 61% of all children brushed their teeth twice or more daily. Overall, 12% of study children had dental erosion with 13% for 2-4 years old and 10% for 12 years old, with the majority of erosive lesions within enamel. Family income (OR 3.98, p = 0.021) and acidic fruit juice consumption (OR 2.38, p = 0.038) were significant risk factors for dental erosion, even after controlling for other factors, such as source of drinking water and oral hygiene using logistic regression analysis. Dental erosion is a relatively common problem among the children in this study and it is seen as a multi-factorial process.

  20. How well does the Post-fire Erosion Risk Management Tool (ERMiT) really work?

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    Robichaud, Peter; Elliot, William; Lewis, Sarah; Miller, Mary Ellen

    2016-04-01

    The decision of where, when, and how to apply the most effective postfire erosion mitigation treatments requires land managers to assess the risk of damaging runoff and erosion events occurring after a fire. The Erosion Risk Management Tool (ERMiT) was developed to assist post fire assessment teams identify high erosion risk areas and effectiveness of various mitigation treatments to reduce that risk. ERMiT is a web-based application that uses the Water Erosion Prediction Project (WEPP) technology to estimate erosion, in probabilistic terms, on burned and recovering forest, range, and chaparral lands with and without the application of mitigation treatments. User inputs are processed by ERMiT to combine rain event variability with spatial and temporal variabilities of hillslope burn severity and soil properties which are then used as WEPP inputs. Since 2007, the model has been used in making hundreds of land management decisions in the US and elsewhere. We use eight published field study sites in the Western US to compare ERMiT predictions to observed hillslope erosion rates. Most sites experience only a few rainfall events that produced runoff and sediment except for a California site with a Mediterranean climate. When hillslope erosion occurred, significant correlations occurred between the observed hillslope erosion and those predicted by ERMiT. Significant correlation occurred for most mitigation treatments as well as the five recovery years. These model validation results suggest reasonable estimates of probabilistic post-fire hillslope sediment delivery when compared to observation.

  1. Mapping regional soil water erosion risk in the Brittany-Loire basin for water management agency

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    Degan, Francesca; Cerdan, Olivier; Salvador-Blanes, Sébastien; Gautier, Jean-Noël

    2014-05-01

    Soil water erosion is one of the main degradation processes that affect soils through the removal of soil particles from the surface. The impacts for environment and agricultural areas are diverse, such as water pollution, crop yield depression, organic matter loss and reduction in water storage capacity. There is therefore a strong need to produce maps at the regional scale to help environmental policy makers and soil and water management bodies to mitigate the effect of water and soil pollution. Our approach aims to model and map soil erosion risk at regional scale (155 000 km²) and high spatial resolution (50 m) in the Brittany - Loire basin. The factors responsible for soil erosion are different according to the spatial and time scales considered. The regional scale entails challenges about homogeneous data sets availability, spatial resolution of results, various erosion processes and agricultural practices. We chose to improve the MESALES model (Le Bissonnais et al., 2002) to map soil erosion risk, because it was developed specifically for water erosion in agricultural fields in temperate areas. The MESALES model consists in a decision tree which gives for each combination of factors the corresponding class of soil erosion risk. Four factors that determine soil erosion risk are considered: soils, land cover, climate and topography. The first main improvement of the model consists in using newly available datasets that are more accurate than the initial ones. The datasets used cover all the study area homogeneously. Soil dataset has a 1/1 000 000 scale and attributes such as texture, soil type, rock fragment and parent material are used. The climate dataset has a spatial resolution of 8 km and a temporal resolution of mm/day for 12 years. Elevation dataset has a spatial resolution of 50 m. Three different land cover datasets are used where the finest spatial resolution is 50 m over three years. Using these datasets, four erosion factors are characterized and

  2. Predicting soil erosion risk at the Alqueva dam watershed

    OpenAIRE

    Ferreira, Vera; Panagopoulos, Thomas

    2012-01-01

    Soil erosion is serious economic and environmental concern. Assessing soil erosion risk in the Alqueva dam watershed is urgently needed to conserve soil and water resources and prevent the accelerated dam siltation, taking into account the possible land-use changes, due to tourism development, intensification of irrigated farming and biomass production, as well as climate change. A comprehensive methodology that integrates Revised Universal Soil Loss Equation (RUSLE) model and Geographic Info...

  3. Dental erosion among South Brazilian adolescents: A 2.5-year longitudinal study.

    Science.gov (United States)

    Brusius, C D; Alves, L S; Susin, C; Maltz, M

    2018-02-01

    This population-based longitudinal study investigated the incidence, progression and risk factors for dental erosion among South Brazilian adolescents. Eight hundred and one schoolchildren attending 42 public and private schools were clinically examined at 12 years of age; clinical examinations were repeated after 2.5 years (SD=0.3). After tooth cleaning and drying, permanent incisors and first molars were classified using the Basic Erosive Wear Examination (BEWE) scoring criteria. Questionnaires were used to collect data on socio-demographic characteristics, dietary habits, toothbrushing frequency and general health. Poisson regression analysis was used to assess the association between dental erosion incidence and explanatory variables, with adjusted incidence risk ratios (IRR) and 95% CI estimated. Among those who did not have dental erosion at baseline, 49 of 680 schoolchildren (7.1%; 95% CI=5.2-9.1) developed erosive lesions over the follow-up period. Among schoolchildren who had dental erosion at baseline, 31 of 121 (25.4%; 95% CI=17.6-33.3) had new or more severe lesions. Boys were more likely to develop dental erosion than girls (IRR=1.88; 95% CI=1.06-3.32). A moderate incidence of dental erosion was observed among South Brazilian adolescents, with boys being at higher risk. The high progression rate of 25% observed here is very concerning, and it should be taken in consideration when designing preventive strategies for dental erosion. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  4. Runoff erosion

    OpenAIRE

    Evelpidou, Niki (Ed.); Cordier, Stephane (Ed.); Merino, Agustin (Ed.); Figueiredo, Tomás de (Ed.); Centeri, Csaba (Ed.)

    2013-01-01

    Table of Contents PART I – THEORY OF RUNOFF EROSION CHAPTER 1 - RUNOFF EROSION – THE MECHANISMS CHAPTER 2 - LARGE SCALE APPROACHES OF RUNOFF EROSION CHAPTER 3 - MEASURING PRESENT RUNOFF EROSION CHAPTER 4 - MODELLING RUNOFF EROSION CHAPTER 5 - RUNOFF EROSION AND HUMAN SOCIETIES: THE INFLUENCE OF LAND USE AND MANAGEMENT PRACTICES ON SOIL EROSION PART II - CASE STUDIES CASE STUDIES – INTRODUCTION: RUNOFF EROSION IN MEDITERRANEAN AREA CASE STUDY 1: Soil Erosion Risk...

  5. Using the Remote Sensing and GIS Technology for Erosion Risk Mapping of Kartalkaya Dam Watershed in Kahramanmaras, Turkey

    Directory of Open Access Journals (Sweden)

    Abdullah E. Akay

    2008-08-01

    Full Text Available The soil erosion is the most serious environmental problem in watershed areas in Turkey. The main factors affecting the amount of soil erosion include vegetation cover, topography, soil, and climate. In order to describe the areas with high soil erosion risks and to develop adequate erosion prevention measures in the watersheds of dams, erosion risk maps should be generated considering these factors. Remote Sensing (RS and Geographic Information System (GIS technologies were used for erosion risk mapping in Kartalkaya Dam Watershed of Kahramanmaras, Turkey, based on the methodology implemented in COoRdination of INformation on the Environment (CORINE model. ASTER imagery was used to generate a land use/cover classification in ERDAS Imagine. The digital maps of the other factors (topography, soil types, and climate were generated in ArcGIS v9.2, and were then integrated as CORINE input files to produce erosion risk maps. The results indicate that 33.82%, 35.44%, and 30.74% of the study area were under low, moderate, and high actual erosion risks, respectively. The CORINE model integrated with RS and GIS technologies has great potential for producing accurate and inexpensive erosion risk maps in Turkey.

  6. Multivariate erosion risk assessment of lateritic badlands of Birbhum

    Indian Academy of Sciences (India)

    Each geomorphic hazard involves a degree of risk which incorporates quantification of the probability that a hazard will be harmful. At present, the categorization of sub-watersheds into erosion risk is considered as the fundamental step to conserve the soil loss. Development of badlands over the laterites of Birbhum district ...

  7. Device closure of secundum atrial septal defect's and the risk of cardiac erosion.

    Science.gov (United States)

    Thomson, J D R; Qureshi, S A

    2015-12-01

    Cardiac erosion related to transcatheter atrial septal defect closure devices is of increasing concern. Erosion is reported to have occurred with most of currently available occluder devices. Perhaps due to the very large number of implants worldwide, the Amplatzer (St Jude) occluder is associated with the majority of cardiac erosion events reported in the literature. Best current estimates of the incidence of erosion with the St Jude device are between one and three cases per 1000 implants. Most events occur early after implantation and it is rare, although not unheard of, for events to occur after a year following device insertion. It is important that those involved with closure programmes are vigilant for the problem, because device-related erosion is associated with a significant mortality risk. Despite considerable debate, the risk factors (either patient or device) for erosion remain unclear and require further investigation. Currently available data sets have focussed largely on erosion cohorts and are unable to place these cases in appropriate context with non-erosion closure cases. What is certain is that programmes implanting these devices must take care to implant appropriately sized devices and have in place plans to ensure that patients are both well informed and can access help and advice in the event of developing symptoms.

  8. Preventing erosive risks after wildfire in Spain: advances and gaps

    Science.gov (United States)

    Fernández Filgueira, Cristina; Vega Hidalgo, José A.; Fontúrbel Lliteras, Teresa

    2017-04-01

    Galicia (NW Spain) is one of the most wildfire-affected areas in Western Europe and where the highest soil losses following fire are recorded in the Iberian Peninsula. During the last decade, mitigation of hydrological and erosive risk has been an important objective for researchers and forest managers. For this reason, research carried out has focused on three main issues: i) the development of operational tools to prioritize post-fire soil stabilization actions, based on soil burn severity indicators and remote sensed information, and testing of their ability to reflect degradation risk in relevant soil properties and subsequent soil erosion, ii) the development and testing of different soil stabilization treatments and their effectiveness for reducing erosion, following their application at broad scale, under the specific environmental conditions of Galicia and iii) the assessment of the performance of current erosion models as well as the development of empirical models to predict post-fire soil losses. On the other hand, the use of forest resources is an essential component of the regional incomes in NW Spain and consequently there is a pressing necessity for investigation on techniques suitable for reconciling soil conservation and sustainable use of those resources. In the framework of wildfire impacts this involve many and complex challenges. This scenario contrast with most of the Iberian Peninsula under Mediterranean influence where salvage logging is not a priority. As in other regions, post-fire hydrologic and erosive risk modeling, including threatened resources vulnerability evaluation is also a capital research need, particularly in a climate change context where dramatic changes in drivers such as precipitation, evapotranspiration and fire regime are expected. The study was funded by the National Institute of Agricultural Research of Spain (INIA) through project RTA2014-00011-C06-02, cofunded by FEDER and the Plan de Mejora e Innovación Forestal de

  9. Prevalence and Extrinsic Risk Factors for Dental Erosion in Adolescents.

    Science.gov (United States)

    Mafla, Ana C; Cerón-Bastidas, Ximena A; Munoz-Ceballos, Maria E; Vallejo-Bravo, Diana C; Fajardo-Santacruz, Maria C

    This manuscript examined the prevalence and extrinsic risk factors for dental erosion (DE) in early and middle adolescents in Pasto, Colombia. Dental erosion was evaluated in a random sample of 384 individuals aged 10-15 years attending three primary and high schools in this cross-sectional study. Clinical dental assessment for DE was done using O'Sullivan index. Data on general sociodemographic variables and extrinsic risks factors were obtained. Descriptive and univariate binary logistic regression analyses were performed. Dental erosion was observed in 57.3% of individuals. The univariate binary logistic regression analysis showed that frequency of drinking natural fruit juices (OR 2.670, 95% CI 1.346 - 5.295, P=0.004) and their pH (OR 2.303, 95% CI 1.292 - 4.107, P=0.004) were more associated with the odd of DE in early adolescence. However, a high SES (OR 10.360, 95% CI 3.700 - 29.010, P<0.001) and frequency of snacks with artificial lemon taste (OR 3.659, 95% CI 1.506 - 8.891, P=0.003) were highly associated with the risk of DE in middle adolescence. The results suggest that DE is a prevalent condition in adolescents living in a city in southern Colombia. The transition from early to middle adolescence implies new bio-psychosocial changes, which increase the risk for DE.

  10. Assessing soil erosion risk using RUSLE through a GIS open source desktop and web application.

    Science.gov (United States)

    Duarte, L; Teodoro, A C; Gonçalves, J A; Soares, D; Cunha, M

    2016-06-01

    Soil erosion is a serious environmental problem. An estimation of the expected soil loss by water-caused erosion can be calculated considering the Revised Universal Soil Loss Equation (RUSLE). Geographical Information Systems (GIS) provide different tools to create categorical maps of soil erosion risk which help to study the risk assessment of soil loss. The objective of this study was to develop a GIS open source application (in QGIS), using the RUSLE methodology for estimating erosion rate at the watershed scale (desktop application) and provide the same application via web access (web application). The applications developed allow one to generate all the maps necessary to evaluate the soil erosion risk. Several libraries and algorithms from SEXTANTE were used to develop these applications. These applications were tested in Montalegre municipality (Portugal). The maps involved in RUSLE method-soil erosivity factor, soil erodibility factor, topographic factor, cover management factor, and support practices-were created. The estimated mean value of the soil loss obtained was 220 ton km(-2) year(-1) ranged from 0.27 to 1283 ton km(-2) year(-1). The results indicated that most of the study area (80 %) is characterized by very low soil erosion level (soil erosion was higher than 962 ton km(-2) year(-1). It was also concluded that areas with high slope values and bare soil are related with high level of erosion and the higher the P and C values, the higher the soil erosion percentage. The RUSLE web and the desktop application are freely available.

  11. Relationship between Risk Behavior for Eating Disorders and Dental Caries and Dental Erosion.

    Science.gov (United States)

    Brandt, Lorenna Mendes Temóteo; Fernandes, Liege Helena Freitas; Aragão, Amanda Silva; Aguiar, Yêska Paola Costa; Auad, Sheyla Márcia; de Castro, Ricardo Dias; Cavalcanti, Sérgio D'Ávila Lins Bezerra; Cavalcanti, Alessandro Leite

    2017-01-01

    The aim of this study was to evaluate whether there is an association between risk behavior for eating disorders (EDs) and dental erosion and caries. A controlled cross-sectional study was conducted in Brazil, involving 850 randomly selected female adolescents. After evaluating risk behavior for eating disorders through the Bulimic Investigatory Test of Edinburgh, 12 adolescents were identified with severe risk behavior for EDs and matched to 48 adolescents without such risk. Dental examinations, anthropometric measurements, and eating habits and oral hygiene were performed. Adolescents with high severity eating disorder condition were not more likely to show dental caries ( p = 0.329; OR = 2.2, 95% CI: 0.35-13.72) or dental erosion ( p = 0.590; OR = 2.33; 95% CI: 0.56-9.70). Adolescents with high body mass index (BMI) were five times more likely to have high severity eating disorder condition ( p = 0.031; OR = 5.1; 95% CI: 1.61-23.07). Therefore, high severity risk behavior for EDs was not significantly associated with dental caries and dental erosion. However, high BMI was a risk factor for developing eating disorders and should be an alert for individuals with this condition.

  12. Erosion risk in the northern Gulf of Mexico - the effects of climate and weather

    Science.gov (United States)

    Wahl, Thomas; Plant, Nathaniel G.; Long, Joseph W.

    2016-04-01

    Oceanographic variables such as mean sea level, tides, storm surges, and waves are drivers of erosion, and they act on different time scales ranging from hours (associated with weather) to seasonal and decadal variations and trends (associated with climate). Here we explore how the related sea-state conditions affect the erosion risk in the northern Gulf of Mexico for past and future climate scenarios. From the climate perspective we find that long-term trends in the relevant variables have caused an increase of ~30% in the erosion risk since the 1980s; at least half of this increase was due to changes in the wave climate. In the next decades, sea level rise will likely become the dominating driver and may, in combination with ongoing changes in the wave climate (and depending on the emission scenario), escalate the erosion risk by up to 300% over the next 30 years. We also find significant changes in the seasonal cycles of sea level and significant wave height, which have in combination caused a considerable increase of the erosion risk in summer and decrease in winter (superimposed onto the long-term trends). The influence of weather is assessed with a copula-based multivariate sea storm model in a Monte-Carlo framework; i.e. we simulate hundreds of thousands of artificial but physically consistent sea-state conditions to quantify how different our understanding of the present day erosion risk would be if we had seen more or less extreme combinations of the different sea-state parameters over the last three decades. We find, for example, that total water levels (tide + surge + wave run-up) associated with 100-year return periods may be underestimated by up to 30% and that the average number of impact hours - when total water levels exceeded the height of the dune toe (collision) or dune crest (overwash) - could have been up to 50% higher than what we inferred based on the actually observed oceanographic conditions. Assessing erosion risk in such a probabilistic

  13. How climate and weather affect the erosion risk in the northern Gulf of Mexico

    Science.gov (United States)

    Wahl, T.; Plant, N. G.

    2015-12-01

    Oceanographic variables such as mean sea level, tides, storm surges, and waves are drivers of erosion, and they act on different time scales ranging from hours (associated with weather) to seasonal and decadal variations and trends (associated with climate). Here we explore how the related sea-state conditions affect the erosion risk in the northern Gulf of Mexico for past and future climate scenarios. From the climate perspective we find that long-term trends in the relevant variables have caused an increase of ~30% in the erosion risk since the 1980s; at least half of this increase was due to changes in the wave climate. In the next decades, sea level rise will likely become the dominating driver and may, in combination with ongoing changes in the wave climate (and depending on the emission scenario), escalate the erosion risk by up to 300% over the next 30 years. We also find significant changes in the seasonal cycles of sea level and significant wave height, which have in combination caused a considerable increase of the erosion risk in summer and decrease in winter (superimposed onto the long-term trends). The influence of weather is assessed with a copula-based multivariate sea storm model in a Monte-Carlo framework; i.e. we simulate hundreds of thousands of artificial but physically consistent sea-state conditions to quantify how different our understanding of the present day erosion risk would be if we had seen more or less extreme combinations of the different sea-state parameters over the last three decades. We find, for example, that total water levels (tide + surge + wave run-up) associated with 100-year return periods may be underestimated by up to 30% and that the average number of impact hours - when total water levels exceeded the height of the dune toe (collision) or dune crest (overwash) - could have been up to 50% higher than what we inferred based on the actually observed oceanographic conditions. Assessing erosion risk in such a probabilistic

  14. Comparison of two occurrence risk assessment methods for collapse gully erosion ——A case study in Guangdong province

    Science.gov (United States)

    Sun, K.; Cheng, D. B.; He, J. J.; Zhao, Y. L.

    2018-02-01

    Collapse gully erosion is a specific type of soil erosion in the red soil region of southern China, and early warning and prevention of the occurrence of collapse gully erosion is very important. Based on the idea of risk assessment, this research, taking Guangdong province as an example, adopt the information acquisition analysis and the logistic regression analysis, to discuss the feasibility for collapse gully erosion risk assessment in regional scale, and compare the applicability of the different risk assessment methods. The results show that in the Guangdong province, the risk degree of collapse gully erosion occurrence is high in northeastern and western area, and relatively low in southwestern and central part. The comparing analysis of the different risk assessment methods on collapse gully also indicated that the risk distribution patterns from the different methods were basically consistent. However, the accuracy of risk map from the information acquisition analysis method was slightly better than that from the logistic regression analysis method.

  15. Integrated spatial assessment of wind erosion risk in Hungary

    Directory of Open Access Journals (Sweden)

    L. Pásztor

    2016-11-01

    Full Text Available Wind erosion susceptibility of Hungarian soils was mapped on the national level integrating three factors of the complex phenomenon of deflation (physical soil features, wind characteristics, and land use and land cover. Results of wind tunnel experiments on erodibility of representative soil samples were used for the parametrization of a countrywide map of soil texture compiled for the upper 5 cm layer of soil, which resulted in a map representing threshold wind velocity exceedance. Average wind velocity was spatially estimated with 0.5′ resolution using the Meteorological Interpolation based on Surface Homogenised Data Basis (MISH method elaborated for the spatial interpolation of surface meteorological elements. The probability of threshold wind velocity exceedance was determined based on values predicted by the soil texture map at the grid locations. Ratio values were further interpolated to a finer 1 ha resolution using sand and silt content of the uppermost (0–5 cm layer of soil as spatial co-variables. Land cover was also taken into account, excluding areas that are not relevant to wind erosion (forests, water bodies, settlements, etc., to spatially assess the risk of wind erosion. According to the resulting map of wind erosion susceptibility, about 10 % of the total area of Hungary can be identified as susceptible to wind erosion. The map gives more detailed insight into the spatial distribution of wind-affected areas in Hungary compared to previous studies.

  16. EFFECTS OF SLOPE SHAPES ON SOIL EROSION

    Directory of Open Access Journals (Sweden)

    Hüseyin ŞENSOY, Şahin PALTA

    2009-01-01

    Full Text Available Water is one of the most important erosive forces. A great number of factors also play a role in erosion process and slope characteristic is also one of them. The steepness and length of the slope are important factors for runoff and soil erosion. Another slope factor that has an effect on erosion is the shape of the slope. Generally, different erosion and runoff characteristics exist in different slopes which can be classified as uniform, concave, convex and complex shape. In this study, the effects of slope shape on erosion are stated and emphasized by taking similar researches into consideration.

  17. Integration of transport concepts for risk assessment of pesticide erosion.

    Science.gov (United States)

    Yang, Xiaomei; Van Der Zee, Sjoerd E A T M; Gai, Lingtong; Wesseling, Jan G; Ritsema, Coen J; Geissen, Violette

    2016-05-01

    Environmental contamination by agrochemicals has been a large problem for decades. Pesticides are transported in runoff and remain attached to eroded soil particles, posing a risk to water and soil quality and human health. We have developed a parsimonious integrative model of pesticide displacement by runoff and erosion that explicitly accounts for water infiltration, erosion, runoff, and pesticide transport and degradation in soil. The conceptual framework was based on broadly accepted assumptions such as the convection-dispersion equation and lognormal distributions of soil properties associated with transport, sorption, degradation, and erosion. To illustrate the concept, a few assumptions are made with regard to runoff in relatively flat agricultural fields: dispersion is ignored and erosion is modelled by a functional relationship. A sensitivity analysis indicated that the total mass of pesticide associated with soil eroded by water scouring increased with slope, rain intensity, and water field capacity of the soil. The mass of transported pesticide decreased as the micro-topography of the soil surface became more distinct. The timing of pesticide spraying and rate of degradation before erosion negatively affected the total amount of transported pesticide. The mechanisms involved in pesticide displacement, such as runoff, infiltration, soil erosion, and pesticide transport and decay in the topsoil, were all explicitly accounted for, so the mathematical complexity of their description can be high, depending on the situation. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Novel Two-Step Classifier for Torsades de Pointes Risk Stratification from Direct Features

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    Jaimit Parikh

    2017-11-01

    Full Text Available While pre-clinical Torsades de Pointes (TdP risk classifiers had initially been based on drug-induced block of hERG potassium channels, it is now well established that improved risk prediction can be achieved by considering block of non-hERG ion channels. The current multi-channel TdP classifiers can be categorized into two classes. First, the classifiers that take as input the values of drug-induced block of ion channels (direct features. Second, the classifiers that are built on features extracted from output of the drug-induced multi-channel blockage simulations in the in-silico models (derived features. The classifiers built on derived features have thus far not consistently provided increased prediction accuracies, and hence casts doubt on the value of such approaches given the cost of including biophysical detail. Here, we propose a new two-step method for TdP risk classification, referred to as Multi-Channel Blockage at Early After Depolarization (MCB@EAD. In the first step, we classified the compound that produced insufficient hERG block as non-torsadogenic. In the second step, the role of non-hERG channels to modulate TdP risk are considered by constructing classifiers based on direct or derived features at critical hERG block concentrations that generates EADs in the computational cardiac cell models. MCB@EAD provides comparable or superior TdP risk classification of the drugs from the direct features in tests against published methods. TdP risk for the drugs highly correlated to the propensity to generate EADs in the model. However, the derived features of the biophysical models did not improve the predictive capability for TdP risk assessment.

  19. Soil Erosion Risk Assessment in Uganda

    Directory of Open Access Journals (Sweden)

    Fidele Karamage

    2017-02-01

    Full Text Available Land use without adequate soil erosion control measures is continuously increasing the risk of soil erosion by water mainly in developing tropical countries. These countries are prone to environmental disturbance due to high population growth and high rainfall intensity. The aim of this study is to assess the state of soil erosion by water in Uganda at national and district levels, for various land cover and land use (LCLU types, in protected areas as well to predict the impact of support practices on soil loss reduction. Predictions obtained using the Revised Universal Soil Loss Equation (RUSLE model indicated that the mean rate of soil loss risk in Uganda’s erosion‐prone lands was 3.2 t∙ha−1∙y−1, resulting in a total annual soil loss of about 62 million tons in 2014. About 39% of the country’s erosion‐prone lands were comprised of unsustainable mean soil loss rates >1 t∙ha−1∙y−1. Out of 112 districts in Uganda, 66 districts were found to have unsustainable estimated soil loss rates >1 t∙ha−1∙y−1. Six districts in Uganda were found to have mean annual soil loss rates of >10 t∙ha−1∙y−1: Bududa (46.3 t∙ha−1∙y−1, Kasese (37.5 t∙ha−1∙y−1, Bundibugyo (28.9 t∙ha−1∙y−1, Bulambuli (20.9 t∙ha−1∙y−1, Sironko (14.6 t∙ha−1∙y−1 and Kotido (12.5 t∙ha−1∙y−1. Among the LCLU types, the highest soil loss rates of 11 t∙ha−1∙y−1 and 10.6 t∙ha−1∙y−1 were found in moderate natural forest and dense natural forest, respectively, mainly due to their locations in highland areas characterized by steep slopes ranging between 16% to 21% and their high rainfall intensity, ranging from 1255 mm∙y−1 to 1292 mm∙y−1. Only five protected areas in Uganda were found to have high mean estimated mean soil loss rates >10 t∙ha−1∙y−1: Rwenzori Mountains (142.94 t∙ha−1∙y−1, Mount Elgon (33.81 t∙ha−1∙y−1, Bokora corridor (12.13 t∙ha−1∙y−1

  20. Extent of Cropland and Related Soil Erosion Risk in Rwanda

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    Fidele Karamage

    2016-06-01

    Full Text Available Land conversion to cropland is one of the major causes of severe soil erosion in Africa. This study assesses the current cropland extent and the related soil erosion risk in Rwanda, a country that experienced the most rapid population growth and cropland expansion in Africa over the last decade. The land cover land use (LCLU map of Rwanda in 2015 was developed using Landsat-8 imagery. Based on the obtained LCLU map and the spatial datasets of precipitation, soil properties and elevation, the soil erosion rate of Rwanda was assessed at 30-m spatial resolution, using the Revised Universal Soil Loss Equation (RUSLE model. According to the results, the mean soil erosion rate was 250 t·ha−1·a−1 over the entire country, with a total soil loss rate of approximately 595 million tons per year. The mean soil erosion rate over cropland, which occupied 56% of the national land area, was estimated at 421 t·ha−1·a−1 and was responsible for about 95% of the national soil loss. About 24% of the croplands in Rwanda had a soil erosion rate larger than 300 t·ha−1·a−1, indicating their unsuitability for cultivation. With a mean soil erosion rate of 1642 t·ha−1·a−1, these unsuitable croplands were responsible for 90% of the national soil loss. Most of the unsuitable croplands are distributed in the Congo Nile Ridge, Volcanic Range mountain areas in the west and the Buberuka highlands in the north, regions characterized by steep slopes (>30% and strong rainfall. Soil conservation practices, such as the terracing cultivation method, are paramount to preserve the soil. According to our assessment, terracing alone could reduce the mean cropland soil erosion rate and the national soil loss by 79% and 75%, respectively. After terracing, only a small proportion of 7.6% of the current croplands would still be exposed to extreme soil erosion with a rate >300 t·ha−1·a−1. These irremediable cropland areas should be returned to mountain forest to

  1. Prevalence and risk factors for dental erosion among 11- to 14-year-old school children in South India.

    Science.gov (United States)

    Kumar, Sandeep; Acharya, Shashidhar; Mishra, Prashant; Debnath, Nitai; Vasthare, Ramprasad

    2013-01-01

    This cross-sectional survey was conducted to assess the prevalence and severity of dental erosion and to determine the potential risk factors for dental erosion among 11- to 14-year-old school children in South India. The total sample size for the study was 605, of which 303 school children were from private schools and 302 from public schools. A questionnaire was designed to record information about socio-demographic characteristics, oral hygiene practices, dietary habits and risk factors for dental erosion. Chi square test, bivariate analysis and Logistic regression analysis were performed to analyse the data. The children who consumed lemon several times a day (OR = 13.41, P dental erosion. The overall prevalence of dental erosion was found to be low (8.9%). Erosion was found to be greater in posterior teeth (65.6%) than anterior teeth (34.4%). Loss of enamel only with loss of surface contour was observed in most (94.8%) of the cases. The prevalence of dental erosion was found to be low in school children. Private school children were affected more by dental erosion. Frequency of lemon consumption and consumption of carbonated drinks were identified as risk factors.

  2. Occurrence of risk factors for dental erosion in the population of young adults in Norway.

    Science.gov (United States)

    Asmyhr, Øyvind; Grytten, Jostein; Holst, Dorthe

    2012-10-01

    The aim of this study was to describe the occurrence of risk factors for dental erosion for a group of young adults who are particularly susceptible to erosion. Another aim was to describe the awareness of erosion and distribution of risk factors according to the educational background of the parents. The sample (n = 2004 individuals) was randomly drawn from the population of 19-20-year-old Norwegians. The data were collected using telephone interviews. We measured awareness about erosion using the following question: 'Have you ever heard about dental erosion?' We obtained information about the frequency of intake of the following risk factors: soft drinks with and without sugar, and juice. Soft drinks with sugar included lemonade (Coca-Cola, Solo, Pepsi, Mozell and ice tea) and sport drinks (XL1, Maxim). Soft drinks without sugar included Cola light, Zero, PepsiMax, Solo light and ice tea light. Juice included orange, grapefruit, apple and kiwi juice. The parents' level of education was based on the Norwegian school system, which has three levels: compulsory schooling (10 years), upper secondary school education (up to 13 years) and university/college education. The data were analysed using logistic regressions analyses. Awareness of erosion was high - 93.5% of respondents were aware of the problem. The majority of respondents believed that erosion can be prevented - altogether 84.9%. They also believed that soft drinks with and without sugar are equally important for the development of erosion. 17.5% of respondents drank soft drinks with sugar daily or several times a day. The corresponding figures for soft drinks without sugar and juice were 4.9% and 34.1%, respectively. Young adults with mothers with high education drank soft drinks both with and without sugar less frequently than those who had mothers with low education. This pattern was the opposite for juice. Consumption of soft drinks and juice is high, even though awareness and knowledge about the causes

  3. Rainfall erosivity map for Ghana

    International Nuclear Information System (INIS)

    Oduro Afriyie, K.

    1995-10-01

    Monthly rainfall data, spanning over a period of more than thirty years, were used to compute rainfall erosivity indices for various stations in Ghana, using the Fournier index, c, defined as p 2 /P, where p is the rainfall amount in the wettest month and P is the annual rainfall amount. Values of the rainfall erosivity indices ranged from 24.5 mm at Sunyani in the mid-portion of Ghana to 180.9 mm at Axim in the south western coastal portion. The indices were used to construct a rainfall erosivity map for the country. The map revealed that Ghana may be broadly divided into five major erosion risk zones. The middle sector of Ghana is generally in the low erosion risk zone; the northern sector is in the moderate to severe erosion risk zone, while the coastal sector is in the severe to extreme severe erosion risk zone. (author). 11 refs, 1 fig., 1 tab

  4. A universal meteorological method to identify potential risk of wind erosion on heavy-textured soils

    Directory of Open Access Journals (Sweden)

    Středová Hana

    2015-06-01

    Full Text Available The climate of Central Europe, mainly winter seasons with no snow cover at lower altitudes and a spring drought as well, might cause erosion events on heavy-textured soils. The aim of this paper is to define a universal method to identify the potential risk of wind erosion on heavy-textured soils. The categorization of potential wind erosion risk due to meteorological conditions is based on: (i an evaluation of the number of freeze-thaw episodes forming bare soil surfaces during the cold period of year; and (ii, an evaluation of the number of days with wet soil surfaces during the cold period of year. In the period 2001–2012 (from November to March, episodes with temperature changes from positive to negative and vice versa (thaw-freeze and freeze-thaw cycles and the effects of wet soil surfaces in connection with aggregate disintegration, are identified. The data are spatially interpolated by GIS tools for areas in the Czech Republic with heavy-textured soils. Blending critical categories is used to locate potential risks. The level of risk is divided into six classes. Those areas identified as potentially most vulnerable are the same localities where the highest number of erosive episodes on heavy-textured soils was documented.

  5. Dynamic Assessment of Soil Erosion Risk Using Landsat TM and HJ Satellite Data in Danjiangkou Reservoir Area, China

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    Pengpeng Han

    2013-08-01

    Full Text Available Danjiangkou reservoir area is the main water source and the submerged area of the Middle Route South-to-North Water Transfer Project of China. Soil erosion is a factor that significantly influences the quality and transfer of water from the Danjiangkou reservoir. The objective of this study is to assess the water erosion (rill and sheet erosion risk and dynamic change trend of spatial distribution in erosion status and intensity between 2004 and 2010 in the Danjiangkou reservoir area using a multicriteria evaluation method.The multicriteria evaluation method synthesizes the vegetation fraction cover, slope gradient, and land use. Based on the rules and erosion risk assessment results of the study area in 2004 and 2010, the research obtained the conservation priority map. This study result shows an improvement in erosion status of the study area, the eroded area decreased from 32.1% in 2004 to 25.43% in 2010. The unchanged regions dominated the study area and that the total area of improvement grade erosion was larger than that of deterioration grade erosion. The severe, more severe, and extremely severe areas decreased by 4.71%, 2.28%, and 0.61% of the total study area, respectively. The percentages of regions where erosion grade transformed from extremely severe to slight, light and moderate were 0.18%, 0.02%, and 0.30%, respectively. However, a deteriorated region with a 2,897.60 km2 area was still observed. This area cannot be ignored in the determination of a general governance scheme. The top two conservation priority levels cover almost all regions with severe erosion and prominent increase in erosion risk, accounting for 7.31% of the study area. The study results can assist government agencies in decision making for determining erosion control areas, starting regulation projects, and making soil conservation measures.

  6. Erosive rainfall in the Rio do Peixe Valley: Part III - Risk of extreme events

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    Álvaro J. Back

    Full Text Available ABSTRACT Understanding the risks of extreme events related to soil erosion is important for adequate dimensioning of erosion and runoff control structures. The objective of this study was to determine the rainfall erosivity with different return periods for the Valley of the Rio do Peixe in Santa Catarina state, Brazil. Daily pluviographic data series from 1984 to 2014 from the Campos Novos, and Videira meteorological stations and from 1986 to 2014 from the Caçador station were used. The data series of maximum annual rainfall intensity in 30 min, maximum annual erosive rainfall, and total annual erosivity were analyzed for each station. The Gumbel-Chow distributions were adjusted and their adhesions were evaluated by the Kolmogorov-Smirnov test at a significance level of 5%. The Gumbel-Chow distribution was adequate for the estimation of all studied variables. The mean annual erosivity corresponds to the return period of 2.25 years. The data series of the annual maximum individual rainfall erosivity coefficients varied from 47 to 50%.

  7. Dental erosion prevalence and associated risk indicators among preschool children in Athens, Greece.

    Science.gov (United States)

    Mantonanaki, Magdalini; Koletsi-Kounari, Haroula; Mamai-Homata, Eleni; Papaioannou, William

    2013-03-01

    The aims of the study were to investigate dental erosion prevalence, distribution and severity in Greek preschool children attending public kindergartens in the prefecture of Attica, Greece and to determine the effect of dental caries, oral hygiene level, socio-economic factors, dental behavior, erosion related medication and chronic illness. A random and stratified sample of 605 Greek preschool children was clinically examined for dental erosion using the Basic Erosive Wear Examination Index (ΒΕWE). Dental caries (dmfs) and Simplified Debris Index were also recorded. The data concerning possible risk indicators were derived by a questionnaire. Zero-inflated Poisson regression was generated to test the predictive effects of the independent variables on dental erosion. The prevalence of dental erosion was 78.8 %, and the mean and SE of BEWE index was 3.64 ± 0.15. High monthly family income was positively related to ΒΕWE cumulative scores [RR = 1.204 (1.016-1.427)], while high maternal education level [RR = 0.872 (0.771-0.986)] and poor oral hygiene level [DI-s, RR = 0.584 (0.450-0.756)] showed a negative association. Dental erosion is a common oral disease in Greek preschool children in Attica, related to oral hygiene and socio-economic factors. Programs aimed at erosion prevention should begin at an early age for all children.

  8. Soil erosion risk assessment using interviews, empirical soil erosion modeling (RUSLE) and fallout radionuclides in a volcanic crater lake watershed subjected to land use change, western Uganda

    Science.gov (United States)

    De Crop, Wannes; Ryken, Nick; Tomma Okuonzia, Judith; Van Ranst, Eric; Baert, Geert; Boeckx, Pascal; Verschuren, Dirk; Verdoodt, Ann

    2017-04-01

    Population pressure results in conversion of natural vegetation to cropland within the western Ugandan crater lake watersheds. These watersheds however are particularly prone to soil degradation and erosion because of the high rainfall intensity and steep topography. Increased soil erosion losses expose the aquatic ecosystems to excessive nutrient loading. In this study, the Katinda crater lake watershed, which is already heavily impacted by agricultural land use, was selected for an explorative study on its (top)soil characteristics - given the general lack of data on soils within these watersheds - as well as an assessment of soil erosion risks. Using group discussions and structured interviews, the local land users' perceptions on land use, soil quality, soil erosion and lake ecology were compiled. Datasets on rainfall, topsoil characteristics, slope gradient and length, and land use were collected. Subsequently a RUSLE erosion model was run. Results from this empirical erosion modeling approach were validated against soil erosion estimates based on 137Cs measurements.

  9. Pedological perspective of gully erosion sites within Kendu ...

    African Journals Online (AJOL)

    Gully erosion is a common feature in western Kenya, rendering large expanses of otherwise arable land uncultivable and uninhabitable. Gully erosion in the area was classified into two types: the Awach-type and the Sondu-type. The current study aimed at providing insight into physical and chemical properties of soil that ...

  10. Evaluation of soil erosion risk using Analytic Network Process and GIS: a case study from Spanish mountain olive plantations.

    Science.gov (United States)

    Nekhay, Olexandr; Arriaza, Manuel; Boerboom, Luc

    2009-07-01

    The study presents an approach that combined objective information such as sampling or experimental data with subjective information such as expert opinions. This combined approach was based on the Analytic Network Process method. It was applied to evaluate soil erosion risk and overcomes one of the drawbacks of USLE/RUSLE soil erosion models, namely that they do not consider interactions among soil erosion factors. Another advantage of this method is that it can be used if there are insufficient experimental data. The lack of experimental data can be compensated for through the use of expert evaluations. As an example of the proposed approach, the risk of soil erosion was evaluated in olive groves in Southern Spain, showing the potential of the ANP method for modelling a complex physical process like soil erosion.

  11. Association between dental erosion and possible risk factors: A hospital-based study in gastroesophageal reflux disease patients

    Directory of Open Access Journals (Sweden)

    Vamsi Krishna Reddy

    2016-01-01

    Full Text Available Introduction: Gastroesophageal reflux disease (GERD is a condition, with a prevalence of up to 10–20% in the general population. GERD may involve damage to the oral cavity, and dental erosion may occur with a higher frequency. Aim: To estimate the prevalence of dental erosion in GERD patients and to evaluate the association between dental erosion and possible risk factors. Materials and Methods: The study was conducted in the Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow among patients attending outpatient department between June and August 2014. The study group comprised 91 subjects with GERD and 114 subjects without GERD. Information regarding symptoms of GERD, medicines, any chronic disease, and dietary habits were recorded. Dental examination was done to assess the presence or absence of dental erosions and its severity was measured using O'Sullivan Index (2000. Statistical analysis was done using Mann–Whitney U-test and Kruskal–Wallis test. Results: Of 91 GERD patients, 87 (95.6% patients had dental erosion. In both groups, association between frequent intake of fruit juice, carbonated drinks, milk, yoghurt, fruits, and tea/coffee with occurrence of dental erosion were statistically significant (P < 0.05. In GERD patients, association between intake of milk and occurrence of dental erosion were statistically significant (P < 0.05. Association of medication with dental erosion was found to be statistically significant (P < 0.05. Chronic diseases like diabetes and asthma were also found to be statistically significant with dental erosion (P < 0.05. Conclusion: This study showed that GERD patients were at increased risk of developing dental erosion compared to controls.

  12. Soil Erosion Analysis in a Small Forested Catchment Supported by ArcGIS Model Builder

    Directory of Open Access Journals (Sweden)

    CSÁFORDI, Péter

    2012-01-01

    Full Text Available To implement the analysis of soil erosion with the USLE in a GIS environment, a new workflow has been developed with the ArcGIS Model Builder. The aim of this four-part framework is to accelerate data processing and to ensure comparability of soil erosion risk maps. The first submodel generates the stream network with connected catchments, computes slope conditions and the LS factor in USLE based on the DEM. The second submodel integrates stream lines, roads, catchment boundaries, land cover, land use, and soil maps. This combined dataset is the basis for the preparation of other USLE-factors. The third submodel estimates soil loss, and creates zonal statistics of soil erosion. The fourth submodel classifies soil loss into categories enabling the comparison of modelled and observed soil erosion. The framework was applied in a small forested catchment in Hungary. Although there is significant deviation between the erosion of different land covers, the predicted specific soil loss does not increase above the tolerance limit in any area unit. The predicted surface soil erosion in forest subcompartments mostly depends on the slope conditions.

  13. Evaluating of the spatial heterogeneity of soil loss tolerance and its effects on erosion risk in the carbonate areas of southern China

    Directory of Open Access Journals (Sweden)

    Y. Li

    2017-05-01

    Full Text Available Soil loss tolerance (T value is one of the criteria in determining the necessity of erosion control measures and ecological restoration strategy. However, the validity of this criterion in subtropical karst regions is strongly disputed. In this study, T value is calculated based on soil formation rate by using a digital distribution map of carbonate rock assemblage types. Results indicated a spatial heterogeneity and diversity in soil loss tolerance. Instead of only one criterion, a minimum of three criteria should be considered when investigating the carbonate areas of southern China because the one region, one T value concept may not be applicable to this region. T value is proportionate to the amount of argillaceous material, which determines the surface soil thickness of the formations in homogenous carbonate rock areas. Homogenous carbonate rock, carbonate rock intercalated with clastic rock areas and carbonate/clastic rock alternation areas have T values of 20, 50 and 100 t/(km2 a, and they are extremely, severely and moderately sensitive to soil erosion. Karst rocky desertification (KRD is defined as extreme soil erosion and reflects the risks of erosion. Thus, the relationship between T value and erosion risk is determined using KRD as a parameter. The existence of KRD land is unrelated to the T value, although this parameter indicates erosion sensitivity. Erosion risk is strongly dependent on the relationship between real soil loss (RL and T value rather than on either erosion intensity or the T value itself. If RL > > T, then the erosion risk is high despite of a low RL. Conversely, if T > > RL, then the soil is safe although RL is high. Overall, these findings may clarify the heterogeneity of T value and its effect on erosion risk in a karst environment.

  14. Minimizing risk associated with shallow burial of waste in semiarid ecosystems: Erosion and vegetation dynamics

    International Nuclear Information System (INIS)

    Breshears, D.D.; Martens, S.N.; Nyhan, J.W.; Springer, E.P.; Wilcox, B.P.

    1994-01-01

    Numerous regulations govern the disposal of low-level radioactive and hazardous waste by burial in shallow pits. The overall goal of these regulations is to reduce the risk to humans and components of the ecosystem for 500 to 1 000 years. Erosional loss of the soil profile covering waste and contamination of groundwater by leachate are two pathways that influence human and ecological risks. Screening calculations for a waste site in a pinyon-juniper woodland at Los Alamos National Laboratory predict the entire 2 m cover of a waste site could be lost by erosion in less than 500 years. In contrast, less than 0.001% of the waste would reach groundwater by leachate. Predicted erosion rates depend highly on plant cover. The boundary between ponderosa pine forest and pinyon-juniper woodland has shifted more than 1 km in less than 50 years in the Los Alamos region and additional boundary shifts have been hypothesized in conjunction with global warming. High erosion rates (> 0.2 cm per year) have been measured in these transition zones. In concert, these results suggest that risk associated with erosional loss of the waste site cover may greatly exceed risks associated with groundwater contamination in semiarid ecosystems

  15. Farmers' identification of erosion indicators and related erosion damage in the Central Highlands of Kenya

    NARCIS (Netherlands)

    Sterk, G.; Okoba, B.O.

    2006-01-01

    Most soil and water conservation planning approaches rely on empirical assessment methods and hardly consider farmers' knowledge of soil erosion processes. Farmers' knowledge of on-site erosion indicators could be useful in assessing the site-specific erosion risk before planning any conservation

  16. Spatial distribution of water erosion risk in a watershed with eucalyptus and Atlantic Forest

    Directory of Open Access Journals (Sweden)

    Junior Cesar Avanzi

    2013-10-01

    Full Text Available The process of water erosion occurs in watersheds throughout the world and it is strongly affected by anthropogenic influences. Thus, the knowledge of these processes is extremely necessary for planning of conservation efforts. This study was performed in an experimental forested watershed in order to predict the average potential annual soil loss by water erosion using the Universal Soil Loss Equation (USLE and a Geographic Information System (GIS, and then compared with soil loss tolerance. All the USLE factors were generated in a distributed approach employing a GIS tool. The layers were multiplied in the GIS framework in order to predict soil erosion rates. Results showed that the average soil loss was 6.2 Mg ha-1 yr-1. Relative to soil loss tolerance, 83% of the area had an erosion rate lesser than the tolerable value. According to soil loss classes, 49% of the watershed had erosion less than 2.5 Mg ha-1 yr-1. However, about 8.7% of the watershed had erosion rates greater than 15 Mg ha-1 yr-1, being mainly related to Plinthosol soil class and roads, thus requiring special attention for the improvement of sustainable management practices for such areas. Eucalyptus cultivation was found to have soil loss greater than Atlantic Forest. Thus, an effort should be made to bring the erosion rates closer to the native forest. Implementation of the USLE model in a GIS framework was found to be a simple and useful tool for predicting the spatial variation of soil erosion risk and identifying critical areas for conservation efforts.

  17. Environmental risks associated to wind erosion in a metal mining area from SE Spain

    International Nuclear Information System (INIS)

    Garcia Fernandez, G.; Romero Diaz, A.

    2009-01-01

    Soils and mining wastes from the Mediterranean mining area placed in the Sierra Minera Mountains are highly enriched in heavy metals such as lead and zinc, but also other metals such as cadmium and arsenic. Wind erosion in this area could be considered extremely high and hazards associated to this eroded sediments seems to be high because the huge amount of metals present in this wastes. Therefore, combination of high erosion rates and high metal concentration in this mining waste, make those environmental risks can be considered high for the surrounding ecosystems, but also for public health of the nearby villages and towns. In order, to study these wind erosion processes over these mining materials, some experiments for the evaluation of the transportation of soil particles were carried out. Erosion rates in this realm is particularly important during spring months, when increased activity of the eastern winds brings intense soil dragging, with strong effects on the metals dispersion, including the massive removal of sediments. (Author) 16 refs.

  18. Environmental risks associated to wind erosion in a metal mining area from SE Spain

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Fernandez, G.; Romero Diaz, A.

    2009-07-01

    Soils and mining wastes from the Mediterranean mining area placed in the Sierra Minera Mountains are highly enriched in heavy metals such as lead and zinc, but also other metals such as cadmium and arsenic. Wind erosion in this area could be considered extremely high and hazards associated to this eroded sediments seems to be high because the huge amount of metals present in this wastes. Therefore, combination of high erosion rates and high metal concentration in this mining waste, make those environmental risks can be considered high for the surrounding ecosystems, but also for public health of the nearby villages and towns. In order, to study these wind erosion processes over these mining materials, some experiments for the evaluation of the transportation of soil particles were carried out. Erosion rates in this realm is particularly important during spring months, when increased activity of the eastern winds brings intense soil dragging, with strong effects on the metals dispersion, including the massive removal of sediments. (Author) 16 refs.

  19. Coastal erosion risk assessment using natural and human factors in different scales.

    Science.gov (United States)

    Alexandrakis, George; Kampanis, Nikolaos

    2015-04-01

    Climate change, including sea-level rise and increasing storms, raise the threats of coastal erosion. Mitigating and adapting to coastal erosion risks in areas of human interest, like urban areas, culture heritage sites, and areas of economic interest, present a major challenge for society. In this context, decision making needs to be based in reliable risk assessment that includes environmental, social and economic factors. By integrating coastal hazard and risk assessments maps into coastal management plans, risks in areas of interest can be reduced. To address this, the vulnerability of the coast to sea level rise and associated erosion, in terms of expected land loss and socioeconomic importance need to be identified. A holistic risk assessment based in environmental, socioeconomic and economics approach can provide managers information how to mitigate the impact of coastal erosion and plan protection measures. Such an approach needs to consider social, economic and environmental factors, which interactions can be better assessed when distributed and analysed along the geographical space. In this work, estimations of climate change impact to coastline are based on a combination of environmental and economic data analysed in a GIS database. The risk assessment is implemented through the estimation of the vulnerability and exposure variables of the coast in two scales. The larger scale estimates the vulnerability in a regional level, with the use environmental factors with the use of CVI. The exposure variable is estimated by the use of socioeconomic factors. Subsequently, a smaller scale focuses on highly vulnerable beaches with high social and economic value. The vulnerability assessment of the natural processes to the environmental characteristics of the beach is estimated with the use of the Beach Vulnerability Index. As exposure variable, the value of beach width that is capitalized in revenues is implemented through a hedonic pricing model. In this

  20. Dental erosion, prevalence and risk factors among a group of adolescents in Stockholm County.

    Science.gov (United States)

    Skalsky Jarkander, M; Grindefjord, M; Carlstedt, K

    2018-02-01

    To investigate the prevalence and risk factors of dental erosion (DE) among a group of adolescents in Stockholm County. This cross sectional cohort study was conducted at three clinics of the Public Dental Service in Stockholm County. Fifteen and 17 year old adolescents (1335) who scheduled their regular dental health examination were asked to participate. After drop-outs a sample of 1071 individuals, 547 males and 524 females were enrolled in the study. Presence of erosive wear was diagnosed (yes/no) on marker teeth by trained dentists/dental hygienists and photographs were taken. The adolescents answered a questionnaire regarding oral symptoms, dietary and behavioural factors. Two calibrated specialist dentists performed evaluation of the photographs for severity of DE using a modified version of the Simplified Erosion Partial Recording System (SEPRS). DE was clinically diagnosed in 28.3% of 15 years old and 34.3% of 17 years old. Severe erosive wear (grade 3 and 4 according to SEPRS) was found in 18.3% of the adolescents based upon the intra-oral photographs. DE was more prevalent and severe among males than females. Clinically diagnosed erosive lesions correlated significantly with soft drink consumption (p < 0.001), the use of juice or sport drinks as a thirst quencher after exercise (p = 0.006) and tooth hypersensitivity when eating and drinking (p = 0.012). Furthermore, self-assessed gastric reflux was a factor strongly associated with DE (p < 0.001). The study indicated that DE was common among adolescents in Stockholm County and associated with both internal and external risk factors.

  1. A clinical index for evaluating and monitoring dental erosion

    DEFF Research Database (Denmark)

    Larsen, I B; Westergaard, J; Stoltze, K

    2000-01-01

    This study describes a new fine-scaled system for classifying initial and advanced dental erosions. The system includes the use of study casts of the teeth in an epoxy resin with an accurate surface reproduction. The severity of erosion on each tooth surface is scored according to six grades...... of severity. In addition, the presence of a Class V restoration and dental erosion on the same surface increases the erosion score, as it is assumed that the need for restorative treatment can be caused by the erosion. A high inter-examiner agreement was found when the present scoring system was used by two...... of the oral cavity and are furthermore suitable for data analysis. The system is thereby well-suited for determining etiologic factors and monitoring the progression of erosion over time....

  2. Preventing erosion at pipeline crossings of watercourses

    International Nuclear Information System (INIS)

    Sawatsky, L.; Arnold, G.

    1997-01-01

    Watercourses are naturally vulnerable to erosion but the risk is particularly acute after sub-soil and armour materials have been disturbed by trenching and backfilling during construction. Various types of erosion (river scour, river bed, river channel bed and river bank ) and the progressive removal of pipeline cover resulting from erosion were discussed. Methods of estimating the risk of progressive erosion, river avulsions and beaver dam scour, and methods of mitigating erosion at pipeline crossings such as deep burial, proper siting, conventional armouring, and a combination of bank toe protection, and upper bank vegetation cover, were described

  3. Quantitative and Qualitative Assessment of Soil Erosion Risk in Małopolska (Poland), Supported by an Object-Based Analysis of High-Resolution Satellite Images

    Science.gov (United States)

    Drzewiecki, Wojciech; Wężyk, Piotr; Pierzchalski, Marcin; Szafrańska, Beata

    2014-06-01

    In 2011 the Marshal Office of Małopolska Voivodeship decided to evaluate the vulnerability of soils to water erosion for the entire region. The quantitative and qualitative assessment of the erosion risk for the soils of the Małopolska region was done based on the USLE approach. The special work-flow of geoinformation technologies was used to fulfil this goal. A high-resolution soil map, together with rainfall data, a detailed digital elevation model and statistical information about areas sown with particular crops created the input information for erosion modelling in GIS environment. The satellite remote sensing technology and the object-based image analysis (OBIA) approach gave valuable support to this study. RapidEye satellite images were used to obtain the essential up-to-date data about land use and vegetation cover for the entire region (15,000 km2). The application of OBIA also led to defining the direction of field cultivation and the mapping of contour tillage areas. As a result, the spatially differentiated values of erosion control practice factor were used. Both, the potential and the actual soil erosion risk were assessed quantificatively and qualitatively. The results of the erosion assessment in the Małopolska Voivodeship reveal the fact that a majority of its agricultural lands is characterized by moderate or low erosion risk levels. However, high-resolution erosion risk maps show its substantial spatial diversity. According to our study, average or higher actual erosion intensity levels occur for 10.6 % of agricultural land, i.e. 3.6 % of the entire voivodeship area. In 20 % of the municipalities there is a very urgent demand for erosion control. In the next 23 % an urgent erosion control is needed. Our study showed that even a slight improvement of P-factor estimation may have an influence on modeling results. In our case, despite a marginal change of erosion assessment figures on a regional scale, the influence on the final prioritization of

  4. Assessment and management of dental erosion.

    Science.gov (United States)

    Wang, Xiaojie; Lussi, Adrian

    2010-07-01

    Studies have shown a growing trend toward increasing prevalence of dental erosion, associated with the declining prevalence of caries disease in industrialized countries. Erosion is an irreversible chemical process that results in tooth substance loss and leaves teeth susceptible to damage as a result of wear over the course of an individual's lifetime. Therefore, early diagnosis and adequate prevention are essential to minimize the risk of tooth erosion. Clinical appearance is the most important sign to be used to diagnose erosion. The Basic Erosive Wear Examination (BEWE) is a simple method to fulfill this task. The determination of a variety of risk and protective factors (patient-dependent and nutrition-dependent factors) as well as their interplay are necessary to initiate preventive measures tailored to the individual. When tooth loss caused by erosive wear reaches a certain level, oral rehabilitation becomes necessary. Copyright 2010 Elsevier Inc. All rights reserved.

  5. Transrectal Mesh Erosion Requiring Bowel Resection.

    Science.gov (United States)

    Kemp, Marta Maria; Slim, Karem; Rabischong, Benoît; Bourdel, Nicolas; Canis, Michel; Botchorishvili, Revaz

    To report a case of a transrectal mesh erosion as complication of laparoscopic promontofixation with mesh repair, necessitating bowel resection and subsequent surgical interventions. Sacrocolpopexy has become a standard procedure for vaginal vault prolapse [1], and the laparoscopic approach has gained popularity owing to more rapid recovery and less morbidity [2,3]. Mesh erosion is a well-known complication of surgical treatment for prolapse as reported in several negative evaluations, including a report from the US Food and Drug Administration in 2011 [4]. Mesh complications are more common after surgeries via the vaginal approach [5]; nonetheless, the incidence of vaginal mesh erosion after laparoscopic procedures is as high as 9% [6]. The incidence of transrectal mesh exposure after laparoscopic ventral rectopexy is roughly 1% [7]. The diagnosis may be delayed because of its rarity and variable presentation. In addition, polyester meshes, such as the mesh used in this case, carry a higher risk of exposure [8]. A 57-year-old woman experiencing genital prolapse, with the cervix classified as +3 according to the Pelvic Organ Prolapse Quantification system, underwent laparoscopic standard sacrocolpopexy using polyester mesh. Subtotal hysterectomy and bilateral adnexectomy were performed concomitantly. A 3-year follow-up consultation demonstrated no signs or symptoms of erosion of any type. At 7 years after the surgery, however, the patient presented with rectal discharge, diagnosed as infectious rectocolitis with the isolation of Clostridium difficile. She underwent a total of 5 repair surgeries in a period of 4 months, including transrectal resection of exposed mesh, laparoscopic ablation of mesh with digestive resection, exploratory laparoscopy with abscess drainage, and exploratory laparoscopy with ablation of residual mesh and transverse colostomy. She recovered well after the last intervention, exhibiting no signs of vaginal or rectal fistula and no recurrence

  6. Soil erodibility mapping using the RUSLE model to prioritize erosion control in the Wadi Sahouat basin, North-West of Algeria.

    Science.gov (United States)

    Toubal, Abderrezak Kamel; Achite, Mohammed; Ouillon, Sylvain; Dehni, Abdelatif

    2018-03-12

    Soil losses must be quantified over watersheds in order to set up protection measures against erosion. The main objective of this paper is to quantify and to map soil losses in the Wadi Sahouat basin (2140 km 2 ) in the north-west of Algeria, using the Revised Universal Soil Loss Equation (RUSLE) model assisted by a Geographic Information System (GIS) and remote sensing. The Model Builder of the GIS allowed the automation of the different operations for establishing thematic layers of the model parameters: the erosivity factor (R), the erodibility factor (K), the topographic factor (LS), the crop management factor (C), and the conservation support practice factor (P). The average annual soil loss rate in the Wadi Sahouat basin ranges from 0 to 255 t ha -1  year -1 , maximum values being observed over steep slopes of more than 25% and between 600 and 1000 m elevations. 3.4% of the basin is classified as highly susceptible to erosion, 4.9% with a medium risk, and 91.6% at a low risk. Google Earth reveals a clear conformity with the degree of zones to erosion sensitivity. Based on the soil loss map, 32 sub-basins were classified into three categories by priority of intervention: high, moderate, and low. This priority is available to sustain a management plan against sediment filling of the Ouizert dam at the basin outlet. The method enhancing the RUSLE model and confrontation with Google Earth can be easily adapted to other watersheds.

  7. Assessing soil erosion risk in the Tillabery landscape, Niger ...

    African Journals Online (AJOL)

    The results show that soil erosion output scenarios predict greater soil erosion in the study area from 2070 onwards. They suggest that human disturbance and topographic factors are the main impact factors in the affected areas. Key words: Tillabéry landscape (Niger), sheet and rill erosion modelling, data mining.

  8. Wildfire disturbance, erosion and sedimentation risks following the Waldo Canyon Fire in Colorado

    Science.gov (United States)

    Flint, K.; Kinoshita, A. M.; Chin, A.; Florsheim, J. L.; Nourbakhshbeidokhti, S.

    2016-12-01

    Wildfire is a landscape-scale disturbance that causes abrupt changes to hydrological responses and sediment flux during subsequent storms. Burning hillslope vegetation during wildfires induces changes to sediment supply and stream flow magnitude. Altered post-fire processes such as channel erosion and sedimentation or flooding enhance downstream hazards that may threaten human populations and physical aquatic habitat over various time scales. Using data from a small drainage basin (Williams Canyon, 4.7 km2) in the Colorado front range burned by the 2012 Waldo Fire as a case study, we investigate post-fire recovery and assess changes in fire-related risks to downstream areas. Our local ground-based precipitation, field measurements, terrestrial Light Detection and Ranging (LiDAR) scanning together with satellite-based remote sensing data (i.e. Landsat) provide a basis for time series analyses of reach-scale erosion and sedimentation response to rainfall patterns as vegetation patterns change following the wildfire. As a first step in quantifying the likelihood and consequences of specific risk scenarios, we examine changes in the combined probability of storm flows and post-fire erosion and sedimentation as vegetation recovers within the study watershed. We explore possible feedbacks and thresholds related to vegetation-hydrology-sediment interactions following wildfire under changing climate regimes. This information is needed to assist in post-fire management to promote sustainability of wildland fluvial systems.

  9. Validation of a probabilistic post-fire erosion model

    Science.gov (United States)

    Pete Robichaud; William J. Elliot; Sarah A. Lewis; Mary Ellen Miller

    2016-01-01

    Post-fire increases of runoff and erosion often occur and land managers need tools to be able to project the increased risk. The Erosion Risk Management Tool (ERMiT) uses the Water Erosion Prediction Project (WEPP) model as the underlying processor. ERMiT predicts the probability of a given amount of hillslope sediment delivery from a single rainfall or...

  10. Wildfires and post-fire erosion risk in a coastal area under severe anthropic pressure associated with the touristic fluxes

    Science.gov (United States)

    Canu, Annalisa; Arca, Bachisio; Pellizzaro, Grazia; Valeriano Pintus, Gian; Ferrara, Roberto; Duce, Pierpaolo

    2017-04-01

    In the last decades a rapid and intense development of the tourism industry led to an increasing of anthropic pressure on several coastal areas of Sardinia. This fact not only modified the coastal aesthetics, but has also generated an increase of risk for the environment. This phenomenon affected also the ancient structure of the landscape with a negative impact mainly caused by the following factors: land abandonment, wildfire occurrence, post-fire erosion, urbanization. These regional changes can be analyzed in detail by considering the geo-diachronic dynamics. The main objectives of this work were i) to perform a diachronic analysis of land use and land cover dynamics, ii) to analyse the recent dynamics of wildfires, and iii) to predict the soil erosion risk in relation to land use change occurred between the 1950s and the 2000s. The study was realized in a coastal area located in North-East Sardinia where the geo-historical processes were summarized and organized in a geographic information system that has been employed to examine the landscape variations at three different time steps: 1954, 1977 and 2000. In addition, different scenarios of wildfire propagation were simulated by FlamMap in order to estimate the spatial pattern of fire danger factors in the study area. Afterwards, maps of post-fire soil erosion were produced to identify the temporal and spatial variations of the erosion risk. The results show how the changes in land use and the significant and rapid increase of the residential areas affect the risk of both wildfires and post-fire soil erosion. The study reveals the capabilities of this type of approach and can be used by management agencies and policy makers e in sustainable landscape management planning. This approach can be extended to other regions of the Mediterranean basin characterized by complex interactions among landscape and anthropic factors affecting the environmental risk.

  11. The prevalence of dental erosion and associated risk factors in 12-13-year-old school children in Southern China.

    Science.gov (United States)

    Wang, Ping; Lin, Huan Cai; Chen, Jian Hong; Liang, Huan You

    2010-08-12

    Dental erosion has been investigated in developed and developing countries and the prevalence varies considerably in different countries, geographic locations, and age groups. With the lifestyle of the Chinese people changing significantly over the decades, dental erosion has begun to receive more attention. However, the information about dental erosion in China is scarce. The purpose of this study was to explore the prevalence of dental erosion and associated risk factors in 12-13-year-old school children in Guangzhou, Southern China. This cross-sectional survey was performed by two trained, calibrated examiners. A stratified random sample of 12-13-year-old children (774 boys and 725 girls) from 10 schools was examined for dental erosion using the diagnostic criteria of Eccles and the index of O'Sullivan was applied to record the distribution, severity, and amount of the lesions. Data on the socio-economic status, health behaviours, and general health involved in the etiology of dental erosion were obtained from a self-completed questionnaire. The analyses were performed using SPSS software. At least one tooth surface with signs of erosion was found in 416 children (27.3%). The most frequently affected teeth were the central incisors (upper central incisors, 16.3% and 15.9%; lower central incisors, 17.4% and 14.8%). The most frequently affected surface was the incisal or occlusal edge (43.2%). The loss of enamel contour was present in 54.6% of the tooth surfaces with erosion. Of the affected tooth surfaces, 69.3% had greater than one-half of the tooth surface was affected. The results from logistic regression analysis demonstrated that the children who were female, consumed carbonated drinks once a week or more, and those whose mothers were educated to the primary level tended to have more dental erosion. Dental erosion in 12-13-year-old Chinese school children is becoming a significant problem. A strategy of offering preventive care, including more campaigns

  12. Erosion and erosion-corrosion

    International Nuclear Information System (INIS)

    Isomoto, Yoshinori

    2008-01-01

    It is very difficult to interpret the technical term of erosion-corrosion' which is sometimes encountered in piping systems of power plants, because of complicated mechanisms and several confusing definitions of erosion-corrosion phenomena. 'FAC (flow accelerated corrosion)' is recently introduced as wall thinning of materials in power plant systems, as a representative of 'erosion-corrosion'. FAC is, however, not necessarily well understood and compared with erosion-corrosion. This paper describes firstly the origin, definition and fundamental understandings of erosion and erosion-corrosion, in order to reconsider and reconfirm the phenomena of erosion, erosion-corrosion and FAC. Next, typical mapping of erosion, corrosion, erosion-corrosion and FAC are introduced in flow velocity and environmental corrosiveness axes. The concept of damage rate in erosion-corrosion is finally discussed, connecting dissolution rate, mass transfer of metal ions in a metal oxide film and film growth. (author)

  13. Modeling runoff and erosion risk in a~small steep cultivated watershed using different data sources: from on-site measurements to farmers' perceptions

    Science.gov (United States)

    Auvet, B.; Lidon, B.; Kartiwa, B.; Le Bissonnais, Y.; Poussin, J.-C.

    2015-09-01

    This paper presents an approach to model runoff and erosion risk in a context of data scarcity, whereas the majority of available models require large quantities of physical data that are frequently not accessible. To overcome this problem, our approach uses different sources of data, particularly on agricultural practices (tillage and land cover) and farmers' perceptions of runoff and erosion. The model was developed on a small (5 ha) cultivated watershed characterized by extreme conditions (slopes of up to 55 %, extreme rainfall events) on the Merapi volcano in Indonesia. Runoff was modelled using two versions of STREAM. First, a lumped version was used to determine the global parameters of the watershed. Second, a distributed version used three parameters for the production of runoff (slope, land cover and roughness), a precise DEM, and the position of waterways for runoff distribution. This information was derived from field observations and interviews with farmers. Both surface runoff models accurately reproduced runoff at the outlet. However, the distributed model (Nash-Sutcliffe = 0.94) was more accurate than the adjusted lumped model (N-S = 0.85), especially for the smallest and biggest runoff events, and produced accurate spatial distribution of runoff production and concentration. Different types of erosion processes (landslides, linear inter-ridge erosion, linear erosion in main waterways) were modelled as a combination of a hazard map (the spatial distribution of runoff/infiltration volume provided by the distributed model), and a susceptibility map combining slope, land cover and tillage, derived from in situ observations and interviews with farmers. Each erosion risk map gives a spatial representation of the different erosion processes including risk intensities and frequencies that were validated by the farmers and by in situ observations. Maps of erosion risk confirmed the impact of the concentration of runoff, the high susceptibility of long steep

  14. Past and future drivers of increased erosion risk in the northern Gulf of Mexico

    Science.gov (United States)

    Wahl, T.; Plant, N. G.

    2014-12-01

    We use hourly observations of water levels from two tide gauges and wave data from three buoys to assess their relative contribution to past and potential future changes in the erosion risk for Dauphin Island, a barrier island located off the coastline of Alabama. Topographic information (i.e. beach slopes and dune toe and crest heights) is obtained from the most recent lidar survey conducted in the area in July 2013. Water levels and wave parameters (i.e. significant wave height and peak period) from the two tide gauges and three wave buoys are merged into single records spanning the period from 1981 to 2013. The Stockdon et al. (2006) run-up model is used to estimate the 2% exceedance values of wave run-up maxima, which are then combined with the observed water levels at the representative tide gauge site to obtain total water levels (TWLs). With this information we assess the relative contribution of geocentric sea level rise, vertical land-movement, and long-term changes in the wave parameters to the observed increase in erosion risk. The latter is approximated using the concept of impact hours per year (IHPY; Ruggiero 2013) at dune toe and dune crest elevation thresholds derived from the lidar data. Wahl et al. (2014) recently discovered a significant increase in the amplitude of the seasonal sea level cycle in the Gulf of Mexico. Here, we explore the potential of these changes, and similar developments in the seasonal cycle of the wave data and corresponding IHPY, to affect coastal erosion. Such intra-annual signals with longer-term variations have not been included in most earlier studies in favour of analysing the effects of annually averaged long-term trends. Finally, scenarios of potential future changes of all relevant parameters are used to explore their relative contribution to further increase in the coastal erosion risk over the next few decades.

  15. Sports drink consumption and dental erosion among amateur runners.

    Science.gov (United States)

    Antunes, Leonardo S; Veiga, Lais; Nery, Victor S; Nery, Caio C; Antunes, Lívia A

    2017-01-01

    This cross-sectional study assessed the prevalence and potential risk factors for dental erosion in amateur athletes at running events. After a sample calculation, 108 runners from the state of Rio de Janeiro, Brazil, were selected and examined for dental wear by a single trained and calibrated evaluator (kappa = 1.00). To identify risk factors, the runners were interviewed by using a standardized, semi-structured questionnaire. The average (SD) age of the runners was 34.2 (11.45), and the prevalence of dental erosion was 19.4%. Gastroesophageal reflux, running frequency per week, and time expended during competition were associated with dental erosion (P dental erosion was not significant (P > 0.05). In conclusion, dental erosion was not associated with use of isotonic drinks. However, frequency of exercise per week and gastroesophageal reflux were risk factors for dental erosion.

  16. Predicting of soil erosion with regarding to rainfall erosivity and soil erodibility

    Science.gov (United States)

    Suif, Zuliziana; Razak, Mohd Amirun Anis Ab; Ahmad, Nordila

    2018-02-01

    The soil along the hill and slope are wearing away due to erosion and it can take place due to occurrence of weak and heavy rainfall. The aim of this study is to predict the soil erosion degree in Universiti Pertahanan Nasional Malaysia (UPNM) area focused on two major factor which is soil erodibility and rainfall erosivity. Soil erodibility is the possibilities of soil to detach and carried away during rainfall and runoff. The "ROM" scale was used in this study to determine the degree of soil erodibility, namely low, moderate, high, and very high. As for rainfall erosivity, the erosive power caused by rainfall that cause soil loss. A daily rainfall data collected from January to April was analyzed by using ROSE index classification to identify the potential risk of soil erosion. The result shows that the soil erodibilty are moderate at MTD`s hill, high at behind of block Lestari and Landslide MTD hill, and critical at behind the mess cadet. While, the highest rainfall erosivity was recorded in March and April. Overall, this study would benefit the organization greatly in saving cost in landslide protection as relevant authorities can take early measures repairing the most affected area of soil erosion.

  17. Quantification and site-specification of the support practice factor when mapping soil erosion risk associated with olive plantations in the Mediterranean island of Crete.

    Science.gov (United States)

    Karydas, Christos G; Sekuloska, Tijana; Silleos, Georgios N

    2009-02-01

    Due to inappropriate agricultural management practices, soil erosion is becoming one of the most dangerous forms of soil degradation in many olive farming areas in the Mediterranean region, leading to significant decrease of soil fertility and yield. In order to prevent further soil degradation, proper measures are necessary to be locally implemented. In this perspective, an increase in the spatial accuracy of remote sensing datasets and advanced image analysis are significant tools necessary and efficient for mapping soil erosion risk on a fine scale. In this study, the Revised Universal Soil Loss Equation (RUSLE) was implemented in the spatial domain using GIS, while a very high resolution satellite image, namely a QuickBird image, was used for deriving cover management (C) and support practice (P) factors, in order to map the risk of soil erosion in Kolymvari, a typical olive farming area in the island of Crete, Greece. The results comprised a risk map of soil erosion when P factor was taken uniform (conventional approach) and a risk map when P factor was quantified site-specifically using object-oriented image analysis. The results showed that the QuickBird image was necessary in order to achieve site-specificity of the P factor and therefore to support fine scale mapping of soil erosion risk in an olive cultivation area, such as the one of Kolymvari in Crete. Increasing the accuracy of the QB image classification will further improve the resulted soil erosion mapping.

  18. An empirical approach to estimate soil erosion risk in Spain.

    Science.gov (United States)

    Martín-Fernández, Luis; Martínez-Núñez, Margarita

    2011-08-01

    Soil erosion is one of the most important factors in land degradation and influences desertification worldwide. In 2001, the Spanish Ministry of the Environment launched the 'National Inventory of Soil Erosion (INES) 2002-2012' to study the process of soil erosion in Spain. The aim of the current article is to assess the usefulness of this National Inventory as an instrument of control, measurement and monitoring of soil erosion in Spain. The methodology and main features of this National Inventory are described in detail. The results achieved as of the end of May 2010 are presented, together with an explanation of the utility of the Inventory as a tool for planning forest hydrologic restoration, soil protection, erosion control, and protection against desertification. Finally, the authors make a comparative analysis of similar initiatives for assessing soil erosion in other countries at the national and European levels. Copyright © 2011 Elsevier B.V. All rights reserved.

  19. DENTAL EROSION IN PRIMARY DENTITION- A REVIEW

    Directory of Open Access Journals (Sweden)

    Rafi Shaik

    2017-06-01

    Full Text Available BACKGROUND The pattern of oral diseases has been influenced by ever changing human lifestyle. Tooth wear especially dental erosion has drawn increasing attention as risk factor for tooth damage or loss in recent years. It is a common condition in primary dentition compared to permanent dentition due to thinner and less mineralised enamel. However, it is more worrying, when this condition is being found in an alarming proportion among children. The presence of dental erosion in children is likely to be associated with a number of general health and dietary factors, but it is also aggravated by the relatively more rapid progression of erosion in the deciduous teeth. An understanding of the aetiologies and risk factors for erosion is important for early recognition of dental erosion to prevent serious irreversible damage to the dentition. This paper discusses the erosion in children with regard to its epidemiology, prevalence, clinical features, measurement and prevention.

  20. The prevalence of dental erosion and associated risk factors in 12-13-year-old school children in Southern China

    Directory of Open Access Journals (Sweden)

    Wang Ping

    2010-08-01

    Full Text Available Abstract Background Dental erosion has been investigated in developed and developing countries and the prevalence varies considerably in different countries, geographic locations, and age groups. With the lifestyle of the Chinese people changing significantly over the decades, dental erosion has begun to receive more attention. However, the information about dental erosion in China is scarce. The purpose of this study was to explore the prevalence of dental erosion and associated risk factors in 12-13-year-old school children in Guangzhou, Southern China. Methods This cross-sectional survey was performed by two trained, calibrated examiners. A stratified random sample of 12-13-year-old children (774 boys and 725 girls from 10 schools was examined for dental erosion using the diagnostic criteria of Eccles and the index of O'Sullivan was applied to record the distribution, severity, and amount of the lesions. Data on the socio-economic status, health behaviours, and general health involved in the etiology of dental erosion were obtained from a self-completed questionnaire. The analyses were performed using SPSS software. Results At least one tooth surface with signs of erosion was found in 416 children (27.3%. The most frequently affected teeth were the central incisors (upper central incisors, 16.3% and 15.9%; lower central incisors, 17.4% and 14.8%. The most frequently affected surface was the incisal or occlusal edge (43.2%. The loss of enamel contour was present in 54.6% of the tooth surfaces with erosion. Of the affected tooth surfaces, 69.3% had greater than one-half of the tooth surface was affected. The results from logistic regression analysis demonstrated that the children who were female, consumed carbonated drinks once a week or more, and those whose mothers were educated to the primary level tended to have more dental erosion. Conclusions Dental erosion in 12-13-year-old Chinese school children is becoming a significant problem. A

  1. Changes in soil erosion and sediment transport based on the RUSLE model in Zhifanggou watershed, China

    Science.gov (United States)

    Wang, Lei; Qian, Ju; Qi, Wen-Yan; Li, Sheng-Shuang; Chen, Jian-Long

    2018-04-01

    In this paper, changes of sediment yield and sediment transport were assessed using the Revised Universal Soil Loss Equation (RUSLE) and Geographical Information Systems (GIS). This model was based on the integrated use of precipitation data, Landsat images in 2000, 2005 and 2010, terrain parameters (slope gradient and slope length) and soil composition in Zhifanggou watershed, Gansu Province, Northwestern China. The obtained results were basically consistent with the measured values. The results showed that the mean modulus of soil erosion is 1224, 1118 and 875 t km-2 yr-1 and annual soil loss is 23 130, 21 130 and 16 536 in 2000, 2005 and 2010 respectively. The measured mean erosion modulus were 1581 and 1377 t km-2 yr-1, and the measured annual soil loss were 29 872 and 26 022 t in 2000 and 2005. From 2000 to 2010, the amount of soil erosion was reduced yearly. Very low erosion and low erosion dominated the soil loss status in the three periods, and moderate erosion followed. The zones classified as very low erosion were increasing, whereas the zones with low or moderate erosion were decreasing. In 2010, no zones were classified as high or very high soil erosion.

  2. Probabilistic assessment of erosion and flooding risk in the northern Gulf of Mexico

    Science.gov (United States)

    Wahl, Thomas; Plant, Nathaniel G.; Long, Joseph W.

    2016-05-01

    We assess erosion and flooding risk in the northern Gulf of Mexico by identifying interdependencies among oceanographic drivers and probabilistically modeling the resulting potential for coastal change. Wave and water level observations are used to determine relationships between six hydrodynamic parameters that influence total water level and therefore erosion and flooding, through consideration of a wide range of univariate distribution functions and multivariate elliptical copulas. Using these relationships, we explore how different our interpretation of the present-day erosion/flooding risk could be if we had seen more or fewer extreme realizations of individual and combinations of parameters in the past by simulating 10,000 physically and statistically consistent sea-storm time series. We find that seasonal total water levels associated with the 100 year return period could be up to 3 m higher in summer and 0.6 m higher in winter relative to our best estimate based on the observational records. Impact hours of collision and overwash—where total water levels exceed the dune toe or dune crest elevations—could be on average 70% (collision) and 100% (overwash) larger than inferred from the observations. Our model accounts for non-stationarity in a straightforward, non-parametric way that can be applied (with little adjustments) to many other coastlines. The probabilistic model presented here, which accounts for observational uncertainty, can be applied to other coastlines where short record lengths limit the ability to identify the full range of possible wave and water level conditions that coastal mangers and planners must consider to develop sustainable management strategies.

  3. Probabilistic assessment of erosion and flooding risk in the northern Gulf of Mexico

    Science.gov (United States)

    Plant, Nathaniel G.; Wahl, Thomas; Long, Joseph W.

    2016-01-01

    We assess erosion and flooding risk in the northern Gulf of Mexico by identifying interdependencies among oceanographic drivers and probabilistically modeling the resulting potential for coastal change. Wave and water level observations are used to determine relationships between six hydrodynamic parameters that influence total water level and therefore erosion and flooding, through consideration of a wide range of univariate distribution functions and multivariate elliptical copulas. Using these relationships, we explore how different our interpretation of the present-day erosion/flooding risk could be if we had seen more or fewer extreme realizations of individual and combinations of parameters in the past by simulating 10,000 physically and statistically consistent sea-storm time series. We find that seasonal total water levels associated with the 100 year return period could be up to 3 m higher in summer and 0.6 m higher in winter relative to our best estimate based on the observational records. Impact hours of collision and overwash—where total water levels exceed the dune toe or dune crest elevations—could be on average 70% (collision) and 100% (overwash) larger than inferred from the observations. Our model accounts for non-stationarity in a straightforward, non-parametric way that can be applied (with little adjustments) to many other coastlines. The probabilistic model presented here, which accounts for observational uncertainty, can be applied to other coastlines where short record lengths limit the ability to identify the full range of possible wave and water level conditions that coastal mangers and planners must consider to develop sustainable management strategies.

  4. Spatio-temporal assessment of soil erosion risk in different agricultural zones of the Inle Lake region, southern Shan State, Myanmar.

    Science.gov (United States)

    Htwe, Thin Nwe; Brinkmann, Katja; Buerkert, Andreas

    2015-10-01

    Myanmar is one of Southeast Asia's climatically most diverse countries, where sheet, rill, and gully erosion affect crop yields and subsequently livelihood strategies of many people. In the unique wetland ecosystem of Inle Lake, soil erosion in surrounding uplands lead to sedimentation and pollution of the water body. The current study uses the Revised Universal Soil Loss Equation (RUSLE) to identify soil erosion risks of the Inle Lake region in space and time and to assess the relationship between soil erosion and degradation for different agricultural zones and cropping systems. Altogether, 85% of soil losses occurred on barren land along the steep slopes. The hotspot of soil erosion risk is situated in the western uplands characterized by unsustainable land use practices combined with a steep topography. The estimated average soil losses amounted to 19.9, 10.1, and 26.2 t ha(-1) yr(-1) in 1989, 2000, and 2009, respectively. These fluctuations were mainly the results of changes in precipitation and land cover (deforestation (-19%) and expansion of annual cropland (+35%) from 1989 to 2009). Most farmers in the study area have not yet adopted effective soil protection measures to mitigate the effects of soil erosion such as land degradation and water pollution of the lake reservoir. This urgently needs to be addressed by policy makers and extension services.

  5. Modelling Soil Erosion in the Densu River Basin Using RUSLE and GIS Tools.

    Science.gov (United States)

    Ashiagbori, G; Forkuo, E K; Laari, P; Aabeyir, R

    2014-07-01

    Soil erosion involves detachment and transport of soil particles from top soil layers, degrading soil quality and reducing the productivity of affected lands. Soil eroded from the upland catchment causes depletion of fertile agricultural land and the resulting sediment deposited at the river networks creates river morphological change and reservoir sedimentation problems. However, land managers and policy makers are more interested in the spatial distribution of soil erosion risk than in absolute values of soil erosion loss. The aim of this paper is to model the spatial distribution of soil erosion in Densu River Basin of Ghana using RUSLE and GIS tools and to use the model to explore the relationship between erosion susceptibility, slope and land use/land cover (LULC) in the Basin. The rainfall map, digital elevation model, soil type map, and land cover map, were input data in the soil erosion model developed. This model was then categorized into four different erosion risk classes. The developed soil erosion map was then overlaid with the slope and LULC maps of the study area to explore their effects on erosion susceptibility of the soil in the Densu River Basin. The Model, predicted 88% of the basin as low erosion risk and 6% as moderate erosion risk, 3% as high erosion risk and 3% as severe risk. The high and severe erosion areas were distributed mainly within the areas of high slope gradient and also sections of the moderate forest LULC class. Also, the areas within the moderate forest LULC class found to have high erosion risk, had an intersecting high erodibility soil group.

  6. Development and validation of a method to estimate the potential wind erosion risk in Germany

    Science.gov (United States)

    Funk, Roger; Deumlich, Detlef; Völker, Lidia

    2017-04-01

    The introduction of the Cross Compliance (CC) regulations for soil protection resulted in the demand for the classification of the the wind erosion risk on agricultural areas in Germany nationwide. A spatial highly resolved method was needed based on uniform data sets and validation principles, which provides a fair and equivalent procedure for all affected farmers. A GIS-procedure was developed, which derives the site specific wind erosion risk from the main influencing factors: soil texture, wind velocity, wind direction and landscape structure following the German standard DIN 19706. The procedure enables different approaches in the Federal States and comparable classification results. Here, we present the approach of the Federal State of Brandenburg. In the first step a complete soil data map was composed in a grid size of 10 x 10 m. Data were taken from 1.) the Soil quality Appraisal (scale 1:10.000), 2.) the Medium-scale Soil Mapping (MMK, 1:25.000), 3.) extrapolating the MMK, 4.) new Soil quality Appraisal (new areas after coal-mining). Based on the texture and carbon content the wind erosion susceptibility was divided in 6 classes. This map was combined with data of the annual average wind velocity resulting in an increase of the risk classes for wind velocities > 5 ms-1 and a decrease for structure is regarded by allocating a height to each landscape element, corresponding to the described features in the digital "Biotope and Land Use Map". The "hill shade" procedure of ArcGIS was used to set virtual shadows behind the landscape elements for eight directions. The relative frequency of wind from each direction was used as a weighting factor and multiplied with the numerical values of the shadowed cells. Depending on the distance to the landscape element the shadowing effect was combined with the risk classes. The results show that the wind erosion risk is obviously reduced by integrating landscape structures into the risk assessment. After the renewed

  7. Pharmacokinetic Tumor Heterogeneity as a Prognostic Biomarker for Classifying Breast Cancer Recurrence Risk.

    Science.gov (United States)

    Mahrooghy, Majid; Ashraf, Ahmed B; Daye, Dania; McDonald, Elizabeth S; Rosen, Mark; Mies, Carolyn; Feldman, Michael; Kontos, Despina

    2015-06-01

    Heterogeneity in cancer can affect response to therapy and patient prognosis. Histologic measures have classically been used to measure heterogeneity, although a reliable noninvasive measurement is needed both to establish baseline risk of recurrence and monitor response to treatment. Here, we propose using spatiotemporal wavelet kinetic features from dynamic contrast-enhanced magnetic resonance imaging to quantify intratumor heterogeneity in breast cancer. Tumor pixels are first partitioned into homogeneous subregions using pharmacokinetic measures. Heterogeneity wavelet kinetic (HetWave) features are then extracted from these partitions to obtain spatiotemporal patterns of the wavelet coefficients and the contrast agent uptake. The HetWave features are evaluated in terms of their prognostic value using a logistic regression classifier with genetic algorithm wrapper-based feature selection to classify breast cancer recurrence risk as determined by a validated gene expression assay. Receiver operating characteristic analysis and area under the curve (AUC) are computed to assess classifier performance using leave-one-out cross validation. The HetWave features outperform other commonly used features (AUC = 0.88 HetWave versus 0.70 standard features). The combination of HetWave and standard features further increases classifier performance (AUCs 0.94). The rate of the spatial frequency pattern over the pharmacokinetic partitions can provide valuable prognostic information. HetWave could be a powerful feature extraction approach for characterizing tumor heterogeneity, providing valuable prognostic information.

  8. Tooth erosion and eating disorders: a systematic review and meta-analysis.

    Directory of Open Access Journals (Sweden)

    Ana Paula Hermont

    Full Text Available BACKGROUND: Eating disorders are associated with the highest rates of morbidity and mortality of any mental disorders among adolescents. The failure to recognize their early signs can compromise a patient's recovery and long-term prognosis. Tooth erosion has been reported as an oral manifestation that might help in the early detection of eating disorders. OBJECTIVES: The aim of this systematic review and meta-analysis was to search for scientific evidence regarding the following clinical question: Do eating disorders increase the risk of tooth erosion? METHODS: An electronic search addressing eating disorders and tooth erosion was conducted in eight databases. Two independent reviewers selected studies, abstracted information and assessed its quality. Data were abstracted for meta-analysis comparing tooth erosion in control patients (without eating disorders vs. patients with eating disorders; and patients with eating disorder risk behavior vs. patients without such risk behavior. Combined odds ratios (ORs and a 95% confidence interval (CI were obtained. RESULTS: Twenty-three papers were included in the qualitative synthesis and assessed by a modified version of the Newcastle-Ottawa Scale. Fourteen papers were included in the meta-analysis. Patients with eating disorders had more risk of tooth erosion (OR = 12.4, 95%CI = 4.1-37.5. Patients with eating disorders who self-induced vomiting had more risk of tooth erosion than those patients who did not self-induce vomiting (OR = 19.6, 95%CI = 5.6-68.8. Patients with risk behavior of eating disorder had more risk of tooth erosion than patients without such risk behavior (Summary OR = 11.6, 95%CI = 3.2-41.7. CONCLUSION: The scientific evidence suggests a causal relationship between tooth erosion and eating disorders and purging practices. Nevertheless, there is a lack of scientific evidence to fulfill the basic criteria of causation between the risk behavior for eating disorders and tooth erosion.

  9. Soil Erosion Risk Map based on irregularity of the vegetative activity

    Science.gov (United States)

    Saa-Requejo, Antonio; Tarquis, Ana Maria; Martín-Sotoca, Juan J.; Valencia, Jose L.; Gobin, Anne; Rodriguez-Sinobas, Leonor

    2016-04-01

    Fournier Index on NDVI values seems to synthesize the different parameters of the USLE, referring to rainfall, soil, geomorphology and vegetation cover. Acknowledgements Authors are grateful to TALE project (CICYT PCIN-2014-080) and DURERO project (Env.C1.3913442) for their financial support. References Fournier, F. (1960), Climat et erosion. P.U.F. Paris. Jensen, J.R. (2000). Remote Sensing of the Environment: An Earth Resource Perpective, Prentice Hall, New Jersey. Martínez Sotoca, J. J. (2014) estructura espacial de la sequía en pastos y sus aplicaciones en el seguro agrario indexado. (In Spanish) Master Thesis, UPM. Shamshad, A., Azhari M.N., Isaac, M.H., wan Hussin, W.M.A., Parida, B.P.. (2008). Development of an appropriate procedure for estimation of RUSLE EI30 index and preparation of erosivity maps for Pulau Penang in Peninsular Malaysia. Catena, 72, 423-432. van der Knijff, J.M., Jones, R.J.A., Montanarella, L. (1999). Soil Erosion Risk Assessment Italy Soil Erosion Risk Assessment in Italy. European Commission Soil Bureau Joint Research Centre European Commission. EUR 19022EN.

  10. Plasma proteomics classifiers improve risk prediction for renal disease in patients with hypertension or type 2 diabetes

    DEFF Research Database (Denmark)

    Pena, Michelle J; Jankowski, Joachim; Heinze, Georg

    2015-01-01

    OBJECTIVE: Micro and macroalbuminuria are strong risk factors for progression of nephropathy in patients with hypertension or type 2 diabetes. Early detection of progression to micro and macroalbuminuria may facilitate prevention and treatment of renal diseases. We aimed to develop plasma...... proteomics classifiers to predict the development of micro or macroalbuminuria in hypertension or type 2 diabetes. METHODS: Patients with hypertension (n = 125) and type 2 diabetes (n = 82) were selected for this case-control study from the Prevention of REnal and Vascular ENd-stage Disease cohort....... RESULTS: In hypertensive patients, the classifier improved risk prediction for transition in albuminuria stage on top of the reference model (C-index from 0.69 to 0.78; P diabetes, the classifier improved risk prediction for transition from micro to macroalbuminuria (C-index from 0...

  11. Soil erosion assessment on hillslope of GCE using RUSLE model

    Science.gov (United States)

    Islam, Md. Rabiul; Jaafar, Wan Zurina Wan; Hin, Lai Sai; Osman, Normaniza; Din, Moktar Aziz Mohd; Zuki, Fathiah Mohamed; Srivastava, Prashant; Islam, Tanvir; Adham, Md. Ibrahim

    2018-06-01

    A new method for obtaining the C factor (i.e., vegetation cover and management factor) of the RUSLE model is proposed. The method focuses on the derivation of the C factor based on the vegetation density to obtain a more reliable erosion prediction. Soil erosion that occurs on the hillslope along the highway is one of the major problems in Malaysia, which is exposed to a relatively high amount of annual rainfall due to the two different monsoon seasons. As vegetation cover is one of the important factors in the RUSLE model, a new method that accounts for a vegetation density is proposed in this study. A hillslope near the Guthrie Corridor Expressway (GCE), Malaysia, is chosen as an experimental site whereby eight square plots with the size of 8× 8 and 5× 5 m are set up. A vegetation density available on these plots is measured by analyzing the taken image followed by linking the C factor with the measured vegetation density using several established formulas. Finally, erosion prediction is computed based on the RUSLE model in the Geographical Information System (GIS) platform. The C factor obtained by the proposed method is compared with that of the soil erosion guideline Malaysia, thereby predicted erosion is determined by both the C values. Result shows that the C value from the proposed method varies from 0.0162 to 0.125, which is lower compared to the C value from the soil erosion guideline, i.e., 0.8. Meanwhile predicted erosion computed from the proposed C value is between 0.410 and 3.925 t ha^{-1 } yr^{-1} compared to 9.367 to 34.496 t ha^{-1} yr^{-1 } range based on the C value of 0.8. It can be concluded that the proposed method of obtaining a reasonable C value is acceptable as the computed predicted erosion is found to be classified as a very low zone, i.e. less than 10 t ha^{-1 } yr^{-1} whereas the predicted erosion based on the guideline has classified the study area as a low zone of erosion, i.e., between 10 and 50 t ha^{-1 } yr^{-1}.

  12. Comparing performance of 30-day readmission risk classifiers among hospitalized primary care patients.

    Science.gov (United States)

    Garrison, Gregory M; Robelia, Paul M; Pecina, Jennifer L; Dawson, Nancy L

    2017-06-01

    Hospital readmission within 30 days of discharge occurs in almost 20% of US Medicare patients and may be a marker of poor quality inpatient care, ineffective hospital to home transitions, or disease severity. Within a patient centered medical home, care transition interventions may only be practical from cost and staffing perspectives if targeted at patients with the greatest risk of readmission. Various scoring algorithms attempt to predict patients at risk for 30-day readmission, but head-to-head comparison of performance is lacking. Compare published scoring algorithms which use generally available electronic medical record data on the same set of hospitalized primary care patients. The LACE index, the LACE+ index, the HOSPITAL score, and the readmission risk score were computed on a consecutive cohort of 26,278 hospital admissions. Classifier performance was assessed by plotting receiver operating characteristic curves comparing the computed score with the actual outcome of death or readmission within 30 days. Statistical significance of differences in performance was assessed using bootstrapping techniques. Correct readmission classification on this cohort was moderate with the following c-statistics: Readmission risk score 0.666; LACE 0.680; LACE+ 0.662; and HOSPITAL 0.675. There was no statistically significant difference in performance between classifiers. Logistic regression based classifiers yield only moderate performance when utilized to predict 30-day readmissions. The task is difficult due to the variety of underlying causes for readmission, nonlinearity, and the arbitrary time period of concern. More sophisticated classification techniques may be necessary to increase performance and allow patient centered medical homes to effectively focus efforts to reduce readmissions. © 2016 John Wiley & Sons, Ltd.

  13. Coastal erosion vulnerability and risk assessment focusing in tourism beach use.

    Science.gov (United States)

    Alexandrakis, George

    2016-04-01

    It is well established that the global market for tourism services is a key source of economic growth. Especially among Mediterranean countries, the tourism sector is one of the principal sectors driving national economies. With the majority of the mass tourism activities concentrated around coastal areas, coastal erosion, inter alia, poses a significant threat to coastal economies that depend heavily on revenues from tourism. The economic implications of beach erosion were mainly focused in the cost of coastal protection measures, instead of the revenue losses from tourism. For this, the vulnerability of the coast to sea level rise and associated erosion, in terms of expected land loss and economic activity need to be identified. To achieve this, a joint environmental and economic evaluation approach of the problem can provide a managerial tool to mitigate the impact of beach erosion in tourism, through realistic cost-benefit scenarios for planning alternative protection measures. Such a multipurpose tool needs to consider social, economic and environmental factors, which relationships can be better understood when distributed and analyzed along the geographical space. The risk assessment is implemented through the estimation of the vulnerability and exposure variables of the coast in two scales. The larger scale estimates the vulnerability in a regional level, with the use environmental factors with the use of CVI. The exposure variable is estimated by the use of socioeconomic factors. Subsequently, a smaller scale focuses on highly vulnerable beaches with high social and economic value. The assessment of the natural processes to the environmental characteristics of the beach is estimated with the use of the Beach Vulnerability Index (BVI) method. As exposure variable, the value of beach width that is capitalized in revenues is implemented through a hedonic pricing model. In this econometric modelling, Beach Value is related with economic and environmental

  14. Erosivity, surface runoff, and soil erosion estimation using GIS-coupled runoff-erosion model in the Mamuaba catchment, Brazil.

    Science.gov (United States)

    Marques da Silva, Richarde; Guimarães Santos, Celso Augusto; Carneiro de Lima Silva, Valeriano; Pereira e Silva, Leonardo

    2013-11-01

    This study evaluates erosivity, surface runoff generation, and soil erosion rates for Mamuaba catchment, sub-catchment of Gramame River basin (Brazil) by using the ArcView Soil and Water Assessment Tool (AvSWAT) model. Calibration and validation of the model was performed on monthly basis, and it could simulate surface runoff and soil erosion to a good level of accuracy. Daily rainfall data between 1969 and 1989 from six rain gauges were used, and the monthly rainfall erosivity of each station was computed for all the studied years. In order to evaluate the calibration and validation of the model, monthly runoff data between January 1978 and April 1982 from one runoff gauge were used as well. The estimated soil loss rates were also realistic when compared to what can be observed in the field and to results from previous studies around of catchment. The long-term average soil loss was estimated at 9.4 t ha(-1) year(-1); most of the area of the catchment (60%) was predicted to suffer from a low- to moderate-erosion risk (soil erosion was estimated to exceed > 12 t ha(-1) year(-1). Expectedly, estimated soil loss was significantly correlated with measured rainfall and simulated surface runoff. Based on the estimated soil loss rates, the catchment was divided into four priority categories (low, moderate, high and very high) for conservation intervention. The study demonstrates that the AvSWAT model provides a useful tool for soil erosion assessment from catchments and facilitates the planning for a sustainable land management in northeastern Brazil.

  15. Evaluating the new soil erosion map of Hungary

    Science.gov (United States)

    Waltner, István; Centeri, Csaba; Takács, Katalin; Pirkó, Béla; Koós, Sándor; László, Péter; Pásztor, László

    2017-04-01

    With growing concerns on the effects of climate change and land use practices on our soil resources, soil erosion by water is becoming a significant issue internationally. Since the 1964 publication of the first soil erosion map of Hungary, there have been several attempts to provide a countrywide assessment of erosion susceptibility. However, there has been no up-to-date map produced in the last decade. In 2016, a new, 1:100 000 scale soil erosion map was published, based on available soil, elevation, land use and meteorological data for the extremely wet year of 2010. The map utilized combined outputs for two spatially explicit methods: the widely used empirical Universal Soil Loss Equation (USLE) and the process-based Pan-European Soil Erosion Risk Assessment (PESERA) models. The present study aims to provide a detailed analysis of the model results. In lieu of available national monitoring data, information from other sources were used. The Soil Degradation Subsystem (TDR) of the National Environmental Information System (OKIR) is a digital database based on a soil survey and farm dairy data collected from representative farms in Hungary. During the survey all kind of degradation forms - including soil erosion - were considered. Agricultural and demographic data was obtained from the Hungarian Central Statistical Office (KSH). Data from an interview-based survey was also used in an attempt to assess public awareness of soil erosion risks. Point-based evaluation of the model results was complemented with cross-regional assessment of soil erosion estimates. This, combined with available demographic information provides us with an opportunity to address soil erosion on a community level, with the identification of regions with the highest risk of being affected by soil erosion.

  16. Estimation model of soil freeze-thaw erosion in Silingco watershed wetland of Northern Tibet.

    Science.gov (United States)

    Kong, Bo; Yu, Huan

    2013-01-01

    The freeze-thaw (FT) erosion is a type of soil erosion like water erosion and wind erosion. Limited by many factors, the grading evaluation of soil FT erosion quantities is not well studied. Based on the comprehensive analysis of the evaluation indices of soil FT erosion, we for the first time utilized the sensitivity of microwave remote sensing technology to soil moisture for identification of FT state. We established an estimation model suitable to evaluate the soil FT erosion quantity in Silingco watershed wetland of Northern Tibet using weighted summation method of six impact factors including the annual FT cycle days, average diurnal FT phase-changed water content, average annual precipitation, slope, aspect, and vegetation coverage. Finally, with the support of GIS, we classified soil FT erosion quantity in Silingco watershed wetland. The results showed that soil FT erosion are distributed in broad areas of Silingco watershed wetland. Different soil FT erosions with different intensities have evidently different spatial and geographical distributions.

  17. A hierachical method for soil erosion assessment and spatial risk modelling

    NARCIS (Netherlands)

    Okoth, P.F.

    2003-01-01

      Though a lot has been done and achieved in erosion research and control in Kenya, most of the erosion research methods have in the past put emphasis more on quantifying soil loss or measuring soil erosion, rather than pinpointing to

  18. The communication of the risk of coastal erosion in Portugal: a global problem, a local trouble

    Directory of Open Access Journals (Sweden)

    Eduardo BASTO

    2014-07-01

    Full Text Available In the past two decades a set of instruments has been devised by the Portuguese authorities to handle the issue of coastal erosion. We argue that this legal apparatus not only lacks the internal integration necessary for its effectiveness, but it also fails to recognise the ways in which the problem materialises in the everyday life of coastal areas. Through a case study in the village of Furadouro in Western Portugal, we demonstrate how this top-down implementation of policies does not promote a true communication of risks, in the sense that the problem of coastal erosion is not “put in common” across levels of governance.

  19. Erosion risk assessment in the southern Amazon - Data Preprocessing, data base application and process based modelling

    Science.gov (United States)

    Schindewolf, Marcus; Herrmann, Marie-Kristin; Herrmann, Anne-Katrin; Schultze, Nico; Amorim, Ricardo S. S.; Schmidt, Jürgen

    2015-04-01

    The study region along the BR 16 highway belongs to the "Deforestation Arc" at the southern border of the Amazon rainforest. At the same time, it incorporates a land use gradient as colonization started in the 1975-1990 in Central Mato Grosso in 1990 in northern Mato Grosso and most recently in 2004-2005 in southern Pará. Based on present knowledge soil erosion is one of the key driver of soil degradation. Hence, there is a strong need to implement soil erosion control measures in eroding landscapes. Planning and dimensioning of such measures require reliable and detailed information on the temporal and spatial distribution of soil loss, sediment transport and deposition. Soil erosion models are increasingly used, in order to simulate the physical processes involved and to predict the effects of soil erosion control measures. The process based EROSION 3D simulation model is used for surveying soil erosion and deposition on regional catchments. Although EROSION 3D is a widespread, extensively validated model, the application of the model on regional scale remains challenging due to the enormous data requirements and complex data processing operations. In this context the study includes the compilation, validation and generalisation of existing land use and soil data in order to generate a consistent EROSION 3D input datasets. As a part of this process a GIS-linked data base application allows to transfer the original soil and land use data into model specific parameter files. This combined methodology provides different risk assessment maps for certain demands on regional scale. Besides soil loss and sediment transport, sediment pass over points into surface water bodies and particle enrichment can be simulated using the EROSION 3D model. Thus the estimation of particle bound nutrient and pollutant inputs into surface water bodies becomes possible. The study ended up in a user-friendly, timesaving and improved software package for the simulation of soil loss and

  20. Dental erosion in groups of Yemeni children and adolescents and the modification of an erosion partial recording system

    OpenAIRE

    Al-Ashtal, Amin Mohsen Saleh; Johansson, Anders; Ridwaan, Omar; Johansson, Ann-Katrin

    2016-01-01

    Background: Dental erosion is a multifactorial oral health problem with an increasing prevalence among children and adolescents in many countries. Awareness of the condition among lay people is generally lacking, and methods for its clinical grading also need further improvements. Aim: The aims of this thesis was to investigate various aspects of dental erosion including prevalence and risk indicators, to evaluate the recording system used, and to assess the awareness of dental erosion in ...

  1. [Assessment of the impacts of soil erosion on water environment based on the integration of soil erosion process and landscape pattern].

    Science.gov (United States)

    Liu, Yu; Wu, Bing-Fang; Zeng, Yuan; Zhang, Lei

    2013-09-01

    The integration of the effects of landscape pattern to the assessment of the impacts of soil erosion on eco-environmental is of practical significance in methodological prospect, being able to provide an approach for identifying water body's sediment source area, assessing the potential risks of sediment export of on-site soil erosion to the target water body, and evaluating the capacity of regional landscape pattern in preventing soil loss. In this paper, the RUSLE model was applied to simulate the on-site soil erosion rate. With the consideration of the soil retention potential of vegetation cover and topography, a quantitative assessment was conducted on the impacts of soil erosion in the water source region of the middle route for South-to-North Water Transfer Project on rivers and reservoirs by delineating landscape pattern at point (or cell) scale and sub-watershed level. At point (or grid cell) scale, the index of soil erosion impact intensity (I) was developed as an indicator of the potential risk of sediment export to the water bodies. At sub-watershed level, the landscape leakiness index (LI) was employed to indicate the sediment retention capacity of a given landscape pattern. The results revealed that integrating the information of landscape pattern and the indices of soil erosion process could spatially effectively reflect the impact intensity of in situ soil erosion on water bodies. The LI was significantly exponentially correlated to the mean sediment retention capacity of landscape and the mean vegetation coverage of watershed, and the sediment yield at sub-watershed scale was significantly correlated to the LI in an exponential regression. It could be concluded that the approach of delineating landscape pattern based on soil erosion process and the integration of the information of landscape pattern with its soil retention potential could provide a new approach for the risk evaluation of soil erosion.

  2. SUSCEPTIBILITY AND RISKS TO WATER EROSION IN THE UPPER OF ARAGUAIA RIVER BASIN (GO/MT, BRAZIL

    Directory of Open Access Journals (Sweden)

    OLIVEIRA, Victoria Christina Vilela

    2005-05-01

    Full Text Available The soil is a very important natural resource to life in general, especially to human life, because it is the base of its activities. However, in some parts of the word it is not exposed to adequate conservational practices, which result in degradation of the quality and negative impacts on the ecosystems and biodiversity. One of this impacts concerns the water erosion, the most important cause of the accelerated loss of properties on agricultural lands by reduction of fertility, desertification and increase of recent sedimentation in the hydrical channels. The laminar erosion is a common form but no evident signs are visible, except when the roots appear on the cultures and pastures. It is caused by runoff, mainly in the tropics.Some soils have high susceptibility and risks to this form of erosion, frequently the fine sandy soils after deforestation of their original cover and replacement by intensive agricultural an pasturage activities without conservational practices.

  3. Development Of Rainfall Erosivity Map For Nigeria | Ogedengbe ...

    African Journals Online (AJOL)

    The indices were used to develop a rainfall erosivity map or Nigeria. The map reveals that Nigeria may be broadly divided into five major erosion risk zones. The south-western part is generally in the low erosion zone, with the exception of the coastal portion of Lagos, Ondo, Edo and Delta states. The south-east and central ...

  4. Mechanisms of erosion of atherosclerotic plaques.

    Science.gov (United States)

    Quillard, Thibaut; Franck, Grégory; Mawson, Thomas; Folco, Eduardo; Libby, Peter

    2017-10-01

    The present review explores the mechanisms of superficial intimal erosion, a common cause of thrombotic complications of atherosclerosis. Human coronary artery atheroma that give rise to thrombosis because of erosion differ diametrically from those associated with fibrous cap rupture. Eroded lesions characteristically contain few inflammatory cells, abundant extracellular matrix, and neutrophil extracellular traps (NETs). Innate immune mechanisms such as engagement of Toll-like receptor 2 (TLR2) on cultured endothelial cells can impair their viability, attachment, and ability to recover a wound. Hyaluronan fragments may serve as endogenous TLR2 ligands. Mouse experiments demonstrate that flow disturbance in arteries with neointimas tailored to resemble features of human eroded plaques disturbs endothelial cell barrier function, impairs endothelial cell viability, recruits neutrophils, and provokes endothelial cells desquamation, NET formation, and thrombosis in a TLR2-dependent manner. Mechanisms of erosion have received much less attention than those that provoke plaque rupture. Intensive statin treatment changes the characteristic of plaques that render them less susceptible to rupture. Thus, erosion may contribute importantly to the current residual burden of risk. Understanding the mechanisms of erosion may inform the development and deployment of novel therapies to combat the remaining atherothrombotic risk in the statin era.

  5. Soil Erosion Estimation Using Remote Sensing Techniques in Wadi Yalamlam Basin, Saudi Arabia

    Directory of Open Access Journals (Sweden)

    Jarbou A. Bahrawi

    2016-01-01

    Full Text Available Soil erosion is one of the major environmental problems in terms of soil degradation in Saudi Arabia. Soil erosion leads to significant on- and off-site impacts such as significant decrease in the productive capacity of the land and sedimentation. The key aspects influencing the quantity of soil erosion mainly rely on the vegetation cover, topography, soil type, and climate. This research studies the quantification of soil erosion under different levels of data availability in Wadi Yalamlam. Remote Sensing (RS and Geographic Information Systems (GIS techniques have been implemented for the assessment of the data, applying the Revised Universal Soil Loss Equation (RUSLE for the calculation of the risk of erosion. Thirty-four soil samples were randomly selected for the calculation of the erodibility factor, based on calculating the K-factor values derived from soil property surfaces after interpolating soil sampling points. Soil erosion risk map was reclassified into five erosion risk classes and 19.3% of the Wadi Yalamlam is under very severe risk (37,740 ha. GIS and RS proved to be powerful instruments for mapping soil erosion risk, providing sufficient tools for the analytical part of this research. The mapping results certified the role of RUSLE as a decision support tool.

  6. Regionalization of monthly rainfall erosivity patternsin Switzerland

    Science.gov (United States)

    Schmidt, Simon; Alewell, Christine; Panagos, Panos; Meusburger, Katrin

    2016-10-01

    One major controlling factor of water erosion is rainfall erosivity, which is quantified as the product of total storm energy and a maximum 30 min intensity (I30). Rainfall erosivity is often expressed as R-factor in soil erosion risk models like the Universal Soil Loss Equation (USLE) and its revised version (RUSLE). As rainfall erosivity is closely correlated with rainfall amount and intensity, the rainfall erosivity of Switzerland can be expected to have a regional characteristic and seasonal dynamic throughout the year. This intra-annual variability was mapped by a monthly modeling approach to assess simultaneously spatial and monthly patterns of rainfall erosivity. So far only national seasonal means and regional annual means exist for Switzerland. We used a network of 87 precipitation gauging stations with a 10 min temporal resolution to calculate long-term monthly mean R-factors. Stepwise generalized linear regression (GLM) and leave-one-out cross-validation (LOOCV) were used to select spatial covariates which explain the spatial and temporal patterns of the R-factor for each month across Switzerland. The monthly R-factor is mapped by summarizing the predicted R-factor of the regression equation and the corresponding residues of the regression, which are interpolated by ordinary kriging (regression-kriging). As spatial covariates, a variety of precipitation indicator data has been included such as snow depths, a combination product of hourly precipitation measurements and radar observations (CombiPrecip), daily Alpine precipitation (EURO4M-APGD), and monthly precipitation sums (RhiresM). Topographic parameters (elevation, slope) were also significant explanatory variables for single months. The comparison of the 12 monthly rainfall erosivity maps showed a distinct seasonality with the highest rainfall erosivity in summer (June, July, and August) influenced by intense rainfall events. Winter months have the lowest rainfall erosivity. A proportion of 62 % of

  7. Comprehensive assessment of soil erosion risk for better land use planning in river basins: Case study of the Upper Blue Nile River.

    Science.gov (United States)

    Haregeweyn, Nigussie; Tsunekawa, Atsushi; Poesen, Jean; Tsubo, Mitsuru; Meshesha, Derege Tsegaye; Fenta, Ayele Almaw; Nyssen, Jan; Adgo, Enyew

    2017-01-01

    In the drought-prone Upper Blue Nile River (UBNR) basin of Ethiopia, soil erosion by water results in significant consequences that also affect downstream countries. However, there have been limited comprehensive studies of this and other basins with diverse agroecologies. We analyzed the variability of gross soil loss and sediment yield rates under present and expected future conditions using a newly devised methodological framework. The results showed that the basin generates an average soil loss rate of 27.5tha -1 yr -1 and a gross soil loss of ca. 473Mtyr -1 , of which, at least 10% comes from gully erosion and 26.7% leaves Ethiopia. In a factor analysis, variation in agroecology (average factor score=1.32) and slope (1.28) were the two factors most responsible for this high spatial variability. About 39% of the basin area is experiencing severe to very severe (>30tha -1 yr -1 ) soil erosion risk, which is strongly linked to population density. Severe or very severe soil erosion affects the largest proportion of land in three subbasins of the UBNR basin: Blue Nile 4 (53.9%), Blue Nile 3 (45.1%), and Jema Shet (42.5%). If appropriate soil and water conservation practices targeted ca. 77.3% of the area with moderate to severe erosion (>15tha -1 yr -1 ), the total soil loss from the basin could be reduced by ca. 52%. Our methodological framework identified the potential risk for soil erosion in large-scale zones, and with a more sophisticated model and input data of higher spatial and temporal resolution, results could be specified locally within these risk zones. Accurate assessment of soil erosion in the UBNR basin would support sustainable use of the basin's land resources and possibly open up prospects for cooperation in the Eastern Nile region. Copyright © 2016 Office national des forêts. Published by Elsevier B.V. All rights reserved.

  8. A Dental Hygienist's and Therapist's Guide to the Management of Tooth Erosion.

    Science.gov (United States)

    Ariyanayagam, Yana

    2016-08-01

    Dental care professionals can support patients to prevent and manage tooth erosion. The role of the dentist is to restore the structure and function of teeth damaged by acid erosion, while the role of the dental hygienist therapist is to work alongside the dentist to help manage and reduce the risk of tooth erosion. This article will highlight how the dental hygienist or therapist can identify tooth erosion. It will describe the features of tooth erosion and outline the causes. This article will discuss preventative care options for patients who are at risk of tooth erosion, including specific oral hygiene instructions, fluoride advice and use of other dental products.

  9. Directional preference and functional outcomes among subjects classified at high psychosocial risk using STarT.

    Science.gov (United States)

    Werneke, Mark W; Edmond, Susan; Young, Michelle; Grigsby, David; McClenahan, Brian; McGill, Troy

    2018-03-14

    Physiotherapy has an important role in managing patients with non-specific low back pain who experience elevated psychosocial distress or risk for chronic disability. In terms of evidence-based physiotherapy practice, cognitive-behavioural approaches for patients at high psychosocial risk are the recommended management to improve patient treatment outcomes. Evidence also suggests that directional preference (DP) is an important treatment effect modifier for prescribing specific exercises for patients to improve outcomes. Little is known about the influence of treatment techniques based on DP on outcomes for patients classified as high psychosocial risk using the Subgroups for Targeted Treatment (STarT) Back Screening Tool. This study aimed to examine the association between functional status (FS) at rehabilitation discharge for patients experiencing low back pain classified at high STarT psychosocial risk and whose symptoms showed a DP versus No-DP. High STarT risk patients (n = 138) completed intake surveys, that is, the lumbar FS of Focus On Therapeutic Outcomes, Inc., and STarT, and were evaluated for DP by physiotherapists credentialed in McKenzie methods. The FS measure of Focus On Therapeutic Outcomes, Inc., was repeated at discharge. DP and No-DP prevalence rates were calculated. Associations between first-visit DP and No-DP and change in FS were assessed using univariate and multivariate regression models controlling for 11 risk-adjusted variables. One hundred nine patients classified as high STarT risk had complete intake and discharge FS and DP data. Prevalence rate for DP was 65.1%. A significant and clinically important difference (7.98 FS points; p = .03) in change in function at discharge between DP and No-DP was observed after controlling for all confounding variables in the final model. Findings suggest that interventions matched to DP are effective for managing high psychological risk patients and may provide physiotherapists with an

  10. Erosion Pressure on the Danish Coasts

    DEFF Research Database (Denmark)

    Sørensen, Carlo Sass; Sørensen, Per; Kroon, Aart

    Coastlines around the world are receding due to coastal erosion.With rising sea levels and a potential climatic deterioration due to climate change, erosion rates are likely to increase at many locations in the future.Together with the current preference of people to settle near or directly...... by the ocean, coastal erosion issues become increasingly more important to the human values at risk. Along many Danish coastlines, hard structures already act as coastal protection in the form of groins, breakwaters, revetments etc. These eroding coasts however still lack sand and where the public, in general......, neglects the need for sand replenishment i.e. in the form of repeated sand nourishments. Here we present a conceptual model and method for dividing coastal erosion into acute and chronic erosion pressure, respectively. We focus on the model use for management and climate change adaptation purposes...

  11. DSM for soil erosion risk in Scotland

    Science.gov (United States)

    Poggio, Laura; Gimona, Alessandro; McLeaod, Jim; Castellazzi, Marie; Baggio Compagnucci, Andrea; Irvine, Justin

    2017-04-01

    Soils play a crucial role in ecosystem functioning, and modelling its risk of degradation is fundamental, especially in the context of climate change. In this work we used continuous 3D soil information derived from digital soil mapping (DSM) approaches to map sediment erosion and deposition patterns due to rainfall. The test area covers the whole of mainland Scotland, excluding the Northern Islands. Soil profiles data were interpolated using a geo-statistical hybrid Generalised Additive Models method for a range of soil properties such as organic matter, texture, soil depth and peat presence. The same method was used to interpolate climatic data and management information. Remote sensing data were integrated in the process and land use data included. Information on grazing (sheep and deer) pressure was taken into account in the modelling. The uncertainty was accounted and propagated across the whole process. The Scottish test case highlights the differences in roles between mineral and organic soils with an assessment adapted to each of them. The results and intermediate steps were compared with available continental scale results. The results show the importance of the use of DSM approaches for modeling soils and ecosystem functions and assessing uncertainty propagation.

  12. Erosion and sedimentation caused by watercourse regulation

    International Nuclear Information System (INIS)

    Dahl, T.E.; Godtland, K.

    1995-01-01

    This report describes the observations made by SINTEF NHL in 1993 - 1994 on the development of erosion in three regulated lakes in Norway: Devdesjavri, Store Maalvatn and Gjevilvatnet. Surveys, profile levelling, water sample analyses, aerial photography etc were all used. Erosion was dramatic in all three magazines the first year of regulation and then slowed down. It has since remained relatively stable. However, there is a risk of further strong erosion connected with flooding tributaries, notably at low water such as usually occurs in spring. This is true in particular of the main river discharging into Devdesjavri, which is subject to landslides, wave and river erosion. In addition, ground water erosion may occur if the magazine is drained too fast. The report is lavishly illustrated with colour pictures of the effects of erosion. 21 refs., 15 figs., 13 tabs

  13. Rainfall erosivity in Europe.

    Science.gov (United States)

    Panagos, Panos; Ballabio, Cristiano; Borrelli, Pasquale; Meusburger, Katrin; Klik, Andreas; Rousseva, Svetla; Tadić, Melita Perčec; Michaelides, Silas; Hrabalíková, Michaela; Olsen, Preben; Aalto, Juha; Lakatos, Mónika; Rymszewicz, Anna; Dumitrescu, Alexandru; Beguería, Santiago; Alewell, Christine

    2015-04-01

    Rainfall is one the main drivers of soil erosion. The erosive force of rainfall is expressed as rainfall erosivity. Rainfall erosivity considers the rainfall amount and intensity, and is most commonly expressed as the R-factor in the USLE model and its revised version, RUSLE. At national and continental levels, the scarce availability of data obliges soil erosion modellers to estimate this factor based on rainfall data with only low temporal resolution (daily, monthly, annual averages). The purpose of this study is to assess rainfall erosivity in Europe in the form of the RUSLE R-factor, based on the best available datasets. Data have been collected from 1541 precipitation stations in all European Union (EU) Member States and Switzerland, with temporal resolutions of 5 to 60 min. The R-factor values calculated from precipitation data of different temporal resolutions were normalised to R-factor values with temporal resolutions of 30 min using linear regression functions. Precipitation time series ranged from a minimum of 5 years to a maximum of 40 years. The average time series per precipitation station is around 17.1 years, the most datasets including the first decade of the 21st century. Gaussian Process Regression (GPR) has been used to interpolate the R-factor station values to a European rainfall erosivity map at 1 km resolution. The covariates used for the R-factor interpolation were climatic data (total precipitation, seasonal precipitation, precipitation of driest/wettest months, average temperature), elevation and latitude/longitude. The mean R-factor for the EU plus Switzerland is 722 MJ mm ha(-1) h(-1) yr(-1), with the highest values (>1000 MJ mm ha(-1) h(-1) yr(-1)) in the Mediterranean and alpine regions and the lowest (<500 MJ mm ha(-1) h(-1) yr(-1)) in the Nordic countries. The erosivity density (erosivity normalised to annual precipitation amounts) was also the highest in Mediterranean regions which implies high risk for erosive events and floods

  14. Role of erosions typical of rheumatoid arthritis in the 2010 ACR/EULAR rheumatoid arthritis classification criteria: results from a very early arthritis cohort.

    Science.gov (United States)

    Brinkmann, Gina Hetland; Norli, Ellen S; Bøyesen, Pernille; van der Heijde, Désirée; Grøvle, Lars; Haugen, Anne J; Nygaard, Halvor; Bjørneboe, Olav; Thunem, Cathrine; Kvien, Tore K; Mjaavatten, Maria D; Lie, Elisabeth

    2017-11-01

    To determine how the European League Against Rheumatism (EULAR) definition of erosive disease (erosion criterion) contributes to the number of patients classified as rheumatoid arthritis (RA) according to the 2010 American College of Rheumatology/EULAR RA classification criteria (2010 RA criteria) in an early arthritis cohort. Patients from the observational study Norwegian Very Early Arthritis Clinic with joint swelling ≤16 weeks, a clinical diagnosis of RA or undifferentiated arthritis, and radiographs of hands and feet were included. Erosive disease was defined according to the EULAR definition accompanying the 2010 RA criteria. We calculated the additional number of patients being classified as RA based on the erosion criteria at baseline and during follow-up. Of the 289 included patients, 120 (41.5%) fulfilled the 2010 RA criteria, whereas 15 (5.2%) fulfilled only the erosion criterion at baseline. 118 patients had radiographic follow-up at 2 years, of whom 6.8% fulfilled the 2010 RA criteria and only one patient fulfilled solely the erosion criterion during follow-up. Few patients with early arthritis were classified as RA based on solely the erosion criteria, and of those who did almost all did so at baseline. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  15. Evaluating the Impacts of Climate Change on Soil Erosion Rates in Central Mexico

    Directory of Open Access Journals (Sweden)

    Santos Martínez-Santiago

    2017-07-01

    Full Text Available Although water-eroded soil (WES resulting from human activities has been recognized as the leading global cause of land degradation, the soil erosion risks from climate change are not clear. Studies have reported that WES is the second most significant cause of soil loss in Mexico, and its future trajectory has not been sufficiently evaluated. The aims of this study are to 1 determine the impacts of climate change on WES and its distribution for the State of Aguascalientes, Mexico, and to 2 compare the present and future soil loss rates for the study unit (SU. The State of Aguascalientes is located in the “Region del Bajio.” The impact of climate change on WES was evaluated using the near-future divided world scenario (A2 presented in the IPCC Fourth Assessment Report. Daily temperature and precipitation data from 18 weather stations were downscaled to model historic laminar water erosion (HLWE and changes therein in the A2 near-future scenario for 2010–2039 (LWEScA2. Due to future changes in mean annual rainfall (MAR levels, a change in the LWEScA2 of between 1.6 and 8.9% could result in average soil losses up to 475.4 t ha-1 yr-1, representing a loss of slightly more than a 30-mm layer of mountain soil per year. The risk zones, classified as class 4 for LWE, are located to western of the State in part of municipalities of Calvillo, Jesus María, San José de Gracia y Cosio, where there are typical hills and falls with soil very sensitive to rain erosion.

  16. Prevalence of dental erosion in Greek minority school children in Istanbul.

    Science.gov (United States)

    Caglar, E; Sandalli, N; Panagiotou, N; Tonguc, K; Kuscu, O O

    2011-10-01

    To evaluate the prevalence and aetiology of dental erosion in Greek minority school children living in Istanbul (Turkey). The present study was initiated in four Greek minority elementary schools in Istanbul where a total of 83 children (46 girls, 37 boys) between ages 7-14 years old were examined. Children were categorised into 7-11 and 12-14 ages groups. Data were obtained by clinical examination, questionnaire and standard data records. All tooth surfaces were examined, dental erosion was recorded per tooth and classified according to the index of Lussi et al. [1996] In the 7-11 yrs old group, 47.4% (n:18) of the children exhibited dental erosion while in 12-14 yrs old group, 52.6% (n:20) of the children exhibited dental erosion. There were no statitistical differences between age, gender groups and findings of dental erosion (p>0.05). However prevalence of dental erosion in 12-14 yrs old was twice that of the 7-11 years old children. In general, an unusual drinking pattern of slow swallowing of beverages significantly affected the prevalence of dental erosion (p=0.03). Multiple regression analysis revealed no relationship between dental erosion and related erosive sources such as medical conditions, brushing habits, swimming, and the consumption of acidic fruit juices and beverages (p>0.05). However it should be noted that the sample size in the current study was small.

  17. Erosion control works and the intensity of soil erosion in the upper part of the river Toplica drainage basin

    International Nuclear Information System (INIS)

    Kostadinov, S; Dragovic, N; Zlatic, M; Todosijevic, M

    2008-01-01

    Aiming at the protection of the future storage 'Selova' against erosion and sediment, and also to protect the settlements and roads in the drainage basin against torrential floods, erosion control works in the upper part of the river Toplica basin, upstream of the storage 'Selova', started in 1947. The works included building-technical works (check dams) and biological works (afforestation and grassing of bare lands and other erosion risk areas). Within the period 1947-2006, the following erosion control works were executed: afforestation of bare lands on the slopes 2,257.00 ha, grassing of bare lands 1,520.00 ha, and altogether 54 dams were constructed in the river Toplica tributaries. This caused the decrease of sediment transport in the main flow of the river Toplica. This paper, based on the field research conducted in two time periods: 1988 and in the period 2004-2007, presents the state of erosion in the basin before erosion control works; type and scope of erosion control works and their effect on the intensity of erosion in the river Toplica basin upstream of the future storage 'Selova'.

  18. The use of edaphic parameters as indicators of soil erosion risk, Rambla of Las Moreras (SE Spain); El uso de parametros edaficos como indicadores de riesgo de erosion. Rambla de Las Moreras, Murcia, Se de Espana

    Energy Technology Data Exchange (ETDEWEB)

    Romero Diaz, A.; Quinonero Rubio, J. M.; Ortiz Silla, R.; Sanchez Navarro, A.; Fernandez-Delgado Juarez, M.; Gil Vazquez, J. M.

    2009-07-01

    One factor that more involved in the soil erosion soil is erodibility. In this paper we study some parameters (texture, structure, organic material, profundity and vegetal cover in the basin of Rambla de las Moreras (Murcia) with the objective of determining whether any of them can server of erosion risk indicators. the results sampling as the organic matter and the stability of aggregates can be good indicators of this. (Author) 6 refs.

  19. Numerical study of impact erosion of multiple solid particle

    Science.gov (United States)

    Zheng, Chao; Liu, Yonghong; Chen, Cheng; Qin, Jie; Ji, Renjie; Cai, Baoping

    2017-11-01

    Material erosion caused by continuous particle impingement during hydraulic fracturing results in significant economic loss and increased production risks. The erosion process is complex and has not been clearly explained through physical experiments. To address this problem, a multiple particle model in a 3D configuration was proposed to investigate the dynamic erosion process. This approach can significantly reduce experiment costs. The numerical model considered material damping and elastic-plastic material behavior of target material. The effects of impact parameters on erosion characteristics, such as plastic deformation, contact time, and energy loss rate, were investigated. Based on comprehensive studies, the dynamic erosion mechanism and geometry evolution of eroded crater was obtained. These findings can provide a detailed erosion process of target material and insights into the material erosion caused by multiple particle impingement.

  20. Rainfall Erosivity Factor for Uasin Gishu Plateau, Kenya | Kariaga ...

    African Journals Online (AJOL)

    Runoff plots were established on bare soil classified as Dystric Nitosols (Typic Rhodudults) at Moi University Main Campus, on Uasin Gishu Plateau, Kenya. The objective of the study was to determine the best erosivity factor for the area. This was found to be EI30, defined as the product of the rainstorm's kinetic energy and ...

  1. A GIS-based estimation of soil erosion parameters for soil loss potential and erosion hazard in the city of Kinshasa, the Democratic Republic of Congo

    Science.gov (United States)

    Tshikeba Kabantu, Martin; Muamba Tshimanga, Raphael; Onema Kileshye, Jean Marie; Gumindoga, Webster; Tshimpampa Beya, Jules

    2018-05-01

    Soil erosion has detrimental impacts on socio economic life, thus increasing poverty. This situation is aggravated by poor planning and lack of infrastructure especially in developing countries. In these countries, efforts to planning are challenged by lack of data. Alternative approaches that use remote sensing and geographical information systems are therefore needed to provide decision makers with the so much needed information for planning purposes. This helps to curb the detrimental impacts of soil erosion, mostly emanating from varied land use conditions. This study was carried out in the city of Kinshasa, the Democratic Republic of Congo with the aim of using alternative sources of data, based on earth observation resources, to determine the spatial distribution of soil loss and erosion hazard in the city of Kinshasa. A combined approach based on remote sensing skills and rational equation of soil erosion estimation was used. Soil erosion factors, including rainfall-runoff erosivity R), soil erodibility (K), slope steepness and length (SL), crop/vegetation and management (C) were calculated for the city of Kinshasa. Results show that soil loss in Kinshasa ranges from 0 to 20 t ha-1 yr-1. Most of the south part of the urban area were prone to erosion. From the total area of Kinshasa (996 500 ha), 25 013 ha (2.3 %) is of very high ( > 15 t ha-1 yr-1) risk of soil erosion. Urban areas consist of 4.3 % of the area with very high ( > 15 t ha-1 yr-1) risk of soil erosion compared to a very high risk of 2.3 % ( > 15 t ha-1 yr-1) in the rural area. The study shows that the soil loss in the study area is mostly driven by slope, elevation, and informal settlements.

  2. Spatial and temporal variation in rainfall erosivity in a Himalayan watershed

    NARCIS (Netherlands)

    Ma, X.; Noordwijk, van M.; Xu, J.; Lu, X.

    2014-01-01

    Global climate change can modify rainfall patterns, leading to more extremes with associated erosion events. Rainfall erosivity, or the R-factor based on the Revised Universal Soil Loss Equation (RUSLE), indicates the potential water erosion risk and it plays an important role in water and soil

  3. Monthly Rainfall Erosivity Assessment for Switzerland

    Science.gov (United States)

    Schmidt, Simon; Meusburger, Katrin; Alewell, Christine

    2016-04-01

    Water erosion is crucially controlled by rainfall erosivity, which is quantified out of the kinetic energy of raindrop impact and associated surface runoff. Rainfall erosivity is often expressed as the R-factor in soil erosion risk models like the Universal Soil Loss Equation (USLE) and its revised version (RUSLE). Just like precipitation, the rainfall erosivity of Switzerland has a characteristic seasonal dynamic throughout the year. This inter-annual variability is to be assessed by a monthly and seasonal modelling approach. We used a network of 86 precipitation gauging stations with a 10-minute temporal resolution to calculate long-term average monthly R-factors. Stepwise regression and Monte Carlo Cross Validation (MCCV) was used to select spatial covariates to explain the spatial pattern of R-factor for each month across Switzerland. The regionalized monthly R-factor is mapped by its individual regression equation and the ordinary kriging interpolation of its residuals (Regression-Kriging). As covariates, a variety of precipitation indicator data has been included like snow height, a combination of hourly gauging measurements and radar observations (CombiPrecip), mean monthly alpine precipitation (EURO4M-APGD) and monthly precipitation sums (Rhires). Topographic parameters were also significant explanatory variables for single months. The comparison of all 12 monthly rainfall erosivity maps showed seasonality with highest rainfall erosivity in summer (June, July, and August) and lowest rainfall erosivity in winter months. Besides the inter-annual temporal regime, a seasonal spatial variability was detectable. Spatial maps of monthly rainfall erosivity are presented for the first time for Switzerland. The assessment of the spatial and temporal dynamic behaviour of the R-factor is valuable for the identification of more susceptible seasons and regions as well as for the application of selective erosion control measures. A combination with monthly vegetation

  4. Mapping monthly rainfall erosivity in Europe.

    Science.gov (United States)

    Ballabio, Cristiano; Borrelli, Pasquale; Spinoni, Jonathan; Meusburger, Katrin; Michaelides, Silas; Beguería, Santiago; Klik, Andreas; Petan, Sašo; Janeček, Miloslav; Olsen, Preben; Aalto, Juha; Lakatos, Mónika; Rymszewicz, Anna; Dumitrescu, Alexandru; Tadić, Melita Perčec; Diodato, Nazzareno; Kostalova, Julia; Rousseva, Svetla; Banasik, Kazimierz; Alewell, Christine; Panagos, Panos

    2017-02-01

    Rainfall erosivity as a dynamic factor of soil loss by water erosion is modelled intra-annually for the first time at European scale. The development of Rainfall Erosivity Database at European Scale (REDES) and its 2015 update with the extension to monthly component allowed to develop monthly and seasonal R-factor maps and assess rainfall erosivity both spatially and temporally. During winter months, significant rainfall erosivity is present only in part of the Mediterranean countries. A sudden increase of erosivity occurs in major part of European Union (except Mediterranean basin, western part of Britain and Ireland) in May and the highest values are registered during summer months. Starting from September, R-factor has a decreasing trend. The mean rainfall erosivity in summer is almost 4 times higher (315MJmmha -1 h -1 ) compared to winter (87MJmmha -1 h -1 ). The Cubist model has been selected among various statistical models to perform the spatial interpolation due to its excellent performance, ability to model non-linearity and interpretability. The monthly prediction is an order more difficult than the annual one as it is limited by the number of covariates and, for consistency, the sum of all months has to be close to annual erosivity. The performance of the Cubist models proved to be generally high, resulting in R 2 values between 0.40 and 0.64 in cross-validation. The obtained months show an increasing trend of erosivity occurring from winter to summer starting from western to Eastern Europe. The maps also show a clear delineation of areas with different erosivity seasonal patterns, whose spatial outline was evidenced by cluster analysis. The monthly erosivity maps can be used to develop composite indicators that map both intra-annual variability and concentration of erosive events. Consequently, spatio-temporal mapping of rainfall erosivity permits to identify the months and the areas with highest risk of soil loss where conservation measures should be

  5. Natural potential of erosion in the periurbane area of São Carlos - SP

    Directory of Open Access Journals (Sweden)

    Fábio G. Pedro

    2004-07-01

    Full Text Available The population growth in urban areas is speeding up the opening of new land parceling, which due to the emergencial characteristics has been done without proper land use planning. This intensive and non-ordered antropic occupation of the urban perimeter is inducing serious erosion problems. To minimize environmental impacts of new antropic occupations is necessary to obtain information of the physical environment properties, mainly related to erosion risk factors. The Universal Soil Loss Equation (USLE developed in the USA has been widely used for the American land use planning and allows determining areas with higher erosion risk in urban areas. The soil and climate (rain parameters joined to the topography, indicate the Natural Erosion Potential of the USLE, when the antropic influence is not taken into consideration. It was done a Natural Erosion Potential map of the urban perimeter of São Carlos city (Brazil, in the scale of 1:10,000 using IDRISI 32 GIS, aiming to indicate the higher risk areas to erosion. The map of Natural Erosion Potential (PNE allowed identifying that the lowest values of PNE occurred at the Northeast, of the studied region, where the land could be used for urban expansion. By the other hand it was found that at Southwest and Southeast the values of PNE, were high, indicating them to be areas not favorable to urban expansion due to higher erosion risk.

  6. Estimating soil erosion risk and evaluating erosion control measures for soil conservation planning at Koga watershed in the highlands of Ethiopia

    Science.gov (United States)

    Molla, Tegegne; Sisheber, Biniam

    2017-01-01

    Soil erosion is one of the major factors affecting sustainability of agricultural production in Ethiopia. The objective of this paper is to estimate soil erosion using the universal soil loss equation (RUSLE) model and to evaluate soil conservation practices in a data-scarce watershed region. For this purpose, soil data, rainfall, erosion control practices, satellite images and topographic maps were collected to determine the RUSLE factors. In addition, measurements of randomly selected soil and water conservation structures were done at three sub-watersheds (Asanat, Debreyakob and Rim). This study was conducted in Koga watershed at upper part of the Blue Nile basin which is affected by high soil erosion rates. The area is characterized by undulating topography caused by intensive agricultural practices with poor soil conservation practices. The soil loss rates were determined and conservation strategies have been evaluated under different slope classes and land uses. The results showed that the watershed is affected by high soil erosion rates (on average 42 t ha-1 yr-1), greater than the maximum tolerable soil loss (18 t ha-1 yr-1). The highest soil loss (456 t ha-1 yr-1) estimated from the upper watershed occurred on cultivated lands of steep slopes. As a result, soil erosion is mainly aggravated by land-use conflicts and topographic factors and the rugged topographic land forms of the area. The study also demonstrated that the contribution of existing soil conservation structures to erosion control is very small due to incorrect design and poor management. About 35 % out of the existing structures can reduce soil loss significantly since they were constructed correctly. Most of the existing structures were demolished due to the sediment overload, vulnerability to livestock damage and intense rainfall. Therefore, appropriate and standardized soil and water conservation measures for different erosion-prone land uses and land forms need to be implemented in Koga

  7. Soil erosion vulnerability in the verde river basin, southern minas gerais

    Directory of Open Access Journals (Sweden)

    Vinícius Augusto de Oliveira

    2014-06-01

    Full Text Available Soil erosion is one of the most significant environmental degradation processes. Mapping and assessment of soil erosion vulnerability is an important tool for planning and management of the natural resources. The objective of the present study was to apply the Revised Universal Soil Loss Equation (RUSLE using GIS tools to the Verde River Basin (VRB, southern Minas Gerais, in order to assess soil erosion vulnerability. A annual rainfall erosivity map was derived from the geographical model adjusted for Southeastern Brazil, calculating an annual value for each pixel. The maps of soil erodibility (K, topographic factor (LS, and use and management of soils (C were developed from soils and their uses map and the digital elevation model (DEM developed for the basin. In a GIS environment, the layers of the factors were combined to create the soil erosion vulnerability map according to RUSLE. The results showed that, in general, the soils of the VRB present a very high vulnerability to water erosion, with 58.68% of soil losses classified as "High" and "Extremely High" classes. In the headwater region of VRB, the predominant classes were "Very High" and "Extremely High" where there is predominance of Cambisols associated with extensive pastures. Furthermore, the integration of RUSLE/GIS showed an efficient tool for spatial characterization of soil erosion vulnerability in this important basin of the Minas Gerais state.

  8. Protection From Dental Erosion: All Fluorides are Not Equal.

    Science.gov (United States)

    Faller, Robert V; Noble, Warden H

    2018-03-01

    All fluoride sources help strengthen teeth against bacterial acids that cause caries. However, excessive exposure to dietary acids, which can result in dental erosion, presents a more aggressive level of challenge compared to caries. Despite the fact that almost all toothpastes contain fluoride, both the incidence and prevalence of dental erosion appear to be on the rise. This article: (1) describes key differences between caries and dental erosion and the ability of different fluoride sources to help prevent erosion; (2) discusses the importance of the evaluation of patients for dental erosion at the earliest stages using the Basic Erosive Wear Examination scoring system to help assess and educate patients; and (3) provides evidence-based information for making specific recommendations to patients with dental erosion. The objective of this article is to assess the comparative ability of fluoride agents to protect against dental erosion. Though all fluorides are able to help strengthen teeth against cariogenic acids, not all available sources of fluoride provide the same level of erosion protection. Daily use of a stabilized stannous fluoride dentifrice has been shown to provide the most effective means of protecting teeth against the increasing risk of dental erosion and erosive tooth wear.

  9. The risk of persistent trophoblastic disease after hydatidiform mole classified by morphology and ploidy

    DEFF Research Database (Denmark)

    Niemann, Isa; Hansen, Estrid S; Sunde, Lone

    2007-01-01

    classifications, and compared the ability of the two classifications to discriminate between patients with and without a substantial risk of persistent trophoblastic disease. METHODS: 294 cases of consecutively collected hydropic placentas clinically suspected of hydatidiform mole made the basis......OBJECTIVE: Hydatidiform mole can be classified by histopathologic characteristics and by genetic constitutions and most complete moles are diploid, whereas most partial moles are triploid. We investigated the concordance between these two classifications, characterized moles with conflicting......-molar miscarriage, 20 were triploids, 2 were diploid androgenetic and 2 were diploid biparental. In 23% of the conceptuses, the histopathologic and genetic classifications were conflicting. 5% of the patients with hydropic placentas classified as partial mole encountered persistent trophoblastic disease; however...

  10. Assessment of mercury erosion by surface water in Wanshan mercury mining area.

    Science.gov (United States)

    Dai, ZhiHui; Feng, Xinbin; Zhang, Chao; Shang, Lihai; Qiu, Guangle

    2013-08-01

    Soil erosion is a main cause of land degradation, and in its accelerated form is also one of the most serious ecological environmental problems. Moreover, there are few studies on migration of mercury (Hg) induced by soil erosion in seriously Hg-polluted districts. This paper selected Wanshan Hg mining area, SW China as the study area. Revised universal soil loss equation (RUSLE) and Geographic information system (GIS) methods were applied to calculate soil and Hg erosion and to classify soil erosion intensity. Our results show that the soil erosion rate can reach up to 600,884tkm(-2)yr(-1). Surfaces associated with very slight and extremely severe erosion include 76.6% of the entire land in Wanshan. Furthermore, the cumulative erosion rates in the area impacted by extremely severe erosion make up 90.5% of the total. On an annual basis, Hg surface erosion load was predicted to be 505kgyr(-1) and the corresponding mean migration flux of Hg was estimated to be 3.02kgkm(-2)yr(-1). The erosion loads of Hg resulting from farmland and meadow soil were 175 and 319kgyr(-1) respectively, which were enhanced compared to other landscape types due to the fact that they are generally located in the steep zones associated with significant reclamation. Contributing to establish a mass balance of Hg in Wanshan Hg mining area, this study supplies a dependable scientific basis for controlling soil and water erosion in the local ecosystems. Land use change is the most effective way for reducing Hg erosion load in Wanshan mining area. Copyright © 2013 Elsevier Inc. All rights reserved.

  11. New neural network classifier of fall-risk based on the Mahalanobis distance and kinematic parameters assessed by a wearable device

    International Nuclear Information System (INIS)

    Giansanti, Daniele; Macellari, Velio; Maccioni, Giovanni

    2008-01-01

    Fall prevention lacks easy, quantitative and wearable methods for the classification of fall-risk (FR). Efforts must be thus devoted to the choice of an ad hoc classifier both to reduce the size of the sample used to train the classifier and to improve performances. A new methodology that uses a neural network (NN) and a wearable device are hereby proposed for this purpose. The NN uses kinematic parameters assessed by a wearable device with accelerometers and rate gyroscopes during a posturography protocol. The training of the NN was based on the Mahalanobis distance and was carried out on two groups of 30 elderly subjects with varying fall-risk Tinetti scores. The validation was done on two groups of 100 subjects with different fall-risk Tinetti scores and showed that, both in terms of specificity and sensitivity, the NN performed better than other classifiers (naive Bayes, Bayes net, multilayer perceptron, support vector machines, statistical classifiers). In particular, (i) the proposed NN methodology improved the specificity and sensitivity by a mean of 3% when compared to the statistical classifier based on the Mahalanobis distance (SCMD) described in Giansanti (2006 Physiol. Meas. 27 1081–90); (ii) the assessed specificity was 97%, the assessed sensitivity was 98% and the area under receiver operator characteristics was 0.965. (note)

  12. Variabilidade espacial de perdas de solo, do potencial natural e risco de erosão em áreas intensamente cultivadas Spatial variability of the soil loss, natural potential and erosion risk in intensively cultivated areas

    Directory of Open Access Journals (Sweden)

    Gláucia de Mello

    2006-06-01

    Full Text Available O objetivo desta pesquisa foi identificar a variabilidade espacial do potencial natural de erosão, das perdas de solo e do risco de erosão em duas áreas intensamente cultivadas, com o intuito de fornecer subsídios na descrição de padrões de ocorrência de erosão. O solo da área, localizado em Monte Alto, SP, foi classificado como Argissolo Vermelho Amarelo (PVA, relevo ondulado e sob diferentes manejos. O solo da área localizado em Jaboticabal, SP, foi classificado como Latossolo Vermelho (LV, relevo suave, cultivado com cana-de-açúcar. O esquema de amostragem constituiu em uma malha irregular. Amostras de solo foram obtidas na profundidade de 0-0,2 m, para cada malha: 88 amostras para a área de Monte Alto (1465 ha e 128 amostras para a área de Jaboticabal (2597 ha. Para obtenção dos valores das variáveis estudadas, empregou-se a EUPS para cada ponto amostrado. Os dados foram submetidos à análise estatística descritiva e geoestatística para definição dos semivariogramas. Para os modelos foi utilizada a interpolação por krigagem. Observou-se a ocorrência de dependência espacial para todas as variáveis. O solo PVA apresentou maiores riscos de erosão, devido ao relevo, uso atual e manejo, comparado com o solo LV.The objective of this work was to identify the spatial variability of the natural erosion potential, soil loss and erosion risk in two intensely cultivated areas, in order to assess the erosion occurrence patterns. The soil of the area located at Monte Alto, São Paulo state, was classified as Paleudalf (PVA with moderately slope, with different managements. The soil of the area located at Jaboticabal, São Paulo state, was classified as Haplortox(LV with gentle slope and cultivated with sugarcane. A irregular grid was imposed on the experimental areas. Soil samples were obtained from 0-0.2 m depth at each grid point: 88 samples in Monte Alto area (1465 ha and 128 samples at Jaboticabal area (2597 ha. In order

  13. Assessing Vulnerability of Lake Erie Landscapes to Soil Erosion: Modelled and Measured Approaches

    Science.gov (United States)

    Joosse, P.; Laamrani, A.; Feisthauer, N.; Li, S.

    2017-12-01

    Loss of soil from agricultural landscapes to Lake Erie via water erosion is a key transport mechanism for phosphorus bound to soil particles. Agriculture is the dominant land use in the Canadian side of the Lake Erie basin with approximately 75% of the 2.3 million hectares under crop or livestock production. The variable geography and diversity of agricultural production systems and management practices makes estimating risk of soil erosion from agricultural landscapes in the Canadian Lake Erie basin challenging. Risk of soil erosion depends on a combination of factors including the extent to which soil remains bare, which differs with crop type and management. Two different approaches of estimating the vulnerability of landscapes to soil erosion will be compared among Soil Landscapes of Canada in the Lake Erie basin: a modelling approach incorporating farm census and soil survey data, represented by the 2011 Agriculture and Agri-Food Canada Agri-Environmental Indicator for Soil Erosion Risk; and, a measured approach using remotely sensed data that quantifies the magnitude of bare and covered soil across the basin. Results from both approaches will be compared by scaling the national level (1:1 million) Soil Erosion Risk Indicator and the remotely sensed data (30x30 m resolution) to the quaternary watershed level.

  14. Using REE tracers to measure sheet erosion changing to rill erosion

    International Nuclear Information System (INIS)

    Liu Puling; Xue Yazhou; Song Wei; Wang Mingyi; Ju Tongjun

    2004-01-01

    Rare Earth Elements (REE) tracer method was used to study sheet erosion changing to rill erosion on slope land. By placing different rare earth elements of different soil depth across a slope in an indoor plot, two simulated rainfalls were applied to study the change of erosion type and the rill erosion process. The results indicate that the main erosion type is sheet erosion at the beginning of the rainfalls, and serious erosion happens after rill erosion appears. Accumulated sheet and rill erosion amounts increase with the rainfalls time. The percentage of sheet erosion amount decreases and rill erosion percentage increases with time. At the end of the rainfalls, the total rill erosion amounts are 4-5 times more than sheet erosion. In this paper, a new REE tracer method was used to quantitatively distinguish sheet and rill erosion amounts. The new REE tracer method should be useful to future studying of erosion processes on slope lands. (authors)

  15. Monitoring and Risk Identification Caused by High Water, Floods and Erosion Processes in Urban Part of Sava Riverbed

    Science.gov (United States)

    Oskoruš, D.; Miković, N.; Ljevar, I.

    2012-04-01

    Riverbed erosion and bottom deepening are part of natural fluvial processes in the upper stream of Sava River. The increasing gradient of those changes is interconnected with the level of human influence in the river basin and riverbed as well. In time period of last forty years the consequences of riverbed erosion are become serious as well as dangerous and they threaten the stability of hydro technical structures. The increasing value of flow velocity in riverbed in urban part of river section during high water level, mud and debris flow during the floods as well, is especially dangerous for old bridges. This paper contains result of velocity measurements during high waters taken by Hydrological Service of Republic Croatia, load transport monitoring during such events and cross sections in some vulnerable location. In this paper is given one example of Jakuševac railway bridge in Zagreb, heavily destroyed during high water event on the 30 March 2009., recently reconstructed by "Croatian Railways" company. Keywords: Riverbed erosion, flow velocity, mud and debris flow, risk identification, stability of bridges

  16. Erosion-corrosion synergistics in the low erosion regime

    International Nuclear Information System (INIS)

    Corey, R.G.; Sethi, V.K.

    1986-01-01

    Many engineering alloys display good high temperature corrosion resistance. However, when they are used in corrosive environments where they are subjected to erosion also, the corrosion resistance has been adversely affected. The phenomenon known as erosion-corrosion is complex and requires detailed investigation of how the erosion and corrosion kinetics interact and compete. At the Kentucky Center for Energy Research Laboratory, an erosion-corrosion tester was used to perform erosion-oxidation tests on 2 1/4 Cr-1 Mo steel at 500-600 0 C using alumina abrasive at low velocities. The erosion-oxidation rate data and morphology of exposed surfaces are consistent with oxide chipping and fracturing being the mode of material loss

  17. Coastal erosion and accretion in Pak Phanang, Thailand by GIS analysis of maps and satellite imagery

    Directory of Open Access Journals (Sweden)

    Sayedur Rahman Chowdhury

    2013-12-01

    Full Text Available Coastal erosion and accretion in Pak Phanang of southern Thailand between 1973 and 2003 was measured using multi-temporal topographic maps and Landsat satellite imageries. Within a GIS environment landward and seaward movements of shoreline was estimated by a transect-based analysis, and amounts of land accretion and erosion were estimated by a parcel-based geoprocessing. The whole longitudinal extent of the 58 kilometer coast was classified based on the erosion and accretion trends during this period using agglomerative hierarchical clustering approach. Erosion and accretion were found variable over time and space, and periodic reversal of status was also noticed in many places. Estimates of erosion were evaluated against field-survey based data, and found reasonably accurate where the rates were relatively great. Smoothing of shoreline datasets was found desirable as its impacts on the estimates remained within tolerable limits.

  18. Prevalence of dental erosion among people with gastroesophageal reflux disease in China.

    Science.gov (United States)

    Li, Wenhao; Liu, Jingming; Chen, Su; Wang, Yao; Zhang, Zhenting

    2017-01-01

    Gastroesophageal reflux disease (GERD) is typically diagnosed based on symptoms of regurgitation and heartburn, although it may also manifest as asthma-like symptoms, laryngitis, or dental erosion. The purpose of this prospective, cross-sectional study was to assess the prevalence of dental erosion in people with GERD and to evaluate the association between GERD and dental erosion. The presence, severity, and pattern of dental erosion was assessed in 51 participants with GERD and 50 participants without GERD using the Smith and Knight tooth wear index. Medical, dietary, and dental histories were collected by questionnaire. Factors potentially related to dental erosion, including GERD, were evaluated by logistic regression. Dental erosion was observed in 31 (60.8%) participants with GERD and 14 (28%) participants without GERD. Bivariate analysis revealed that participants with GERD were more likely to experience dental erosion (crude odds ratio [cOR]: 2.74; 95% CI: 1.19, 6.32) than participants without GERD. Multivariate analysis also revealed that participants with GERD had a higher risk of dental erosion (adjusted odds ratio [aOR]: 3.97; 95% CI: 1.45, 10.89). Consumption of grains and legumes, the most frequently consumed foods in China, did not correlate with dental erosion. However, carbonated beverage consumption was significantly associated with GERD and dental erosion (aOR: 3.34; 95% CI: 1.01, 11.04; P=.04). GERD was positively correlated with dental erosion. Carbonated beverage consumption can increase the risk of both GERD and dental erosion. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  19. Variability of Rainfall Erosivity and Erosivity Density in the Ganjiang River Catchment, China: Characteristics and Influences of Climate Change

    Directory of Open Access Journals (Sweden)

    Xianghu Li

    2018-02-01

    Full Text Available Soil erosion is one of the most critical environmental hazards in the world. Understanding the changes in rainfall erosivity (RE and erosivity density (ED, as well as their affecting factors, at local and catchment scales in the context of climate warming is an important prerequisite of soil erosion prevention and soil loss risk assessment. The present study identified the variability and trends of RE and ED in terms of both time and space in the Ganjiang River catchment over the period of 1960–2012, and also analyzed and discussed the impact of climate change. The results show that RE and ED in the catchment had great monthly variations and high year-to-year variability. Both presented long-term increasing trends over the entire study period. The highest RE and ED were observed in June and in the eastern and northeast parts of the catchment, which indicated that June was the most susceptible month for soil erosion in this area and the lower reaches of the Ganjiang River was the riskiest area for soil erosion. Finally, the East Asian summer monsoon and climate change were highly correlated with changes in RE and ED.

  20. Heterogeneity wavelet kinetics from DCE-MRI for classifying gene expression based breast cancer recurrence risk.

    Science.gov (United States)

    Mahrooghy, Majid; Ashraf, Ahmed B; Daye, Dania; Mies, Carolyn; Feldman, Michael; Rosen, Mark; Kontos, Despina

    2013-01-01

    Breast tumors are heterogeneous lesions. Intra-tumor heterogeneity presents a major challenge for cancer diagnosis and treatment. Few studies have worked on capturing tumor heterogeneity from imaging. Most studies to date consider aggregate measures for tumor characterization. In this work we capture tumor heterogeneity by partitioning tumor pixels into subregions and extracting heterogeneity wavelet kinetic (HetWave) features from breast dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) to obtain the spatiotemporal patterns of the wavelet coefficients and contrast agent uptake from each partition. Using a genetic algorithm for feature selection, and a logistic regression classifier with leave one-out cross validation, we tested our proposed HetWave features for the task of classifying breast cancer recurrence risk. The classifier based on our features gave an ROC AUC of 0.78, outperforming previously proposed kinetic, texture, and spatial enhancement variance features which give AUCs of 0.69, 0.64, and 0.65, respectively.

  1. Determination of Erosion Hazard Level And Bio-Mechanical Conservation In Post Merapi Eruption Land At Srumbung Magelang

    Directory of Open Access Journals (Sweden)

    S Setyo Wardoyo

    2016-08-01

    Full Text Available The purpose of this study was to determine the Erosion hazard, to look for conservation of bio - mechanical techniques are appropriate . Research methods with overlies topographic maps, soil maps, land use maps, to obtain a Land Unit Map. Determined soil physical properties (texture, structure, permeability and chemical properties of soil (soil organic matter, slope, slope length, broad of land unit, crops factor and value conservation factors that have been there for Land Unit. Each land unit is determined the amount of land erosion and erosion hazard level. Erosion hazard level is determined based on soil erosion, and soil depth. Erosion hazzard level is used to determine the bio-mechanical conservation, according Hardjowigeno and Sukmana (1995. The results showed that the highest erosion hazard level with an area of 12.947 ha is classified weight (Land unit 15A, and the classification of an area of 14.665 ha is clssified moderately (Land unit 6A. Soil conservation is done in areas with highest erosion hazard level by making individual terraces and “kerandang” planted as a cover crops.

  2. Simulating soil erosion risk for Pan-European land use and climate scenarios

    NARCIS (Netherlands)

    Mantel, S.; Kirby, M.; Daroussin, J.; Jones, R.J.A.

    2003-01-01

    Soil is a vital resource with multiple functions and with high regional and internal variability. Accelerated soil erosion is a cause for decline in soil quality and is increasingly being recognized as a serious environmental problem. Soil erosion is a function of factors such as: land use and

  3. Using high-resolution radar images to determine vegetation cover for soil erosion assessments.

    Science.gov (United States)

    Bargiel, D; Herrmann, S; Jadczyszyn, J

    2013-07-30

    Healthy soils are crucial for human well-being. Because soils are threatened worldwide, politicians recognize the need for soil protection. For example, the European Commission has launched the Thematic Strategy for Soil Protection, which requests the European member states to identify high risk areas for soil degradation. Most states use the Universal Soil Loss Equation (USLE) to assess soil erosion risk at the national scale. The USLE includes different factors, one of them is the vegetation cover and management factor (C factor). Modern satellite-based radar sensors now provide highly accurate vegetation cover data, enabling opportunities to improve the accuracy of the C factor. The presented study proves the suitability for C factor determination based on a multi-temporal classification of high-resolution radar images. Further USLE factors were derived from existing data sources (meteorological data, soil maps, digital elevation model) to conduct an USLE-based soil erosion assessment. The resulting map illustrates a qualitative assessment for soil erosion risk within a plot of about 7*12 km in an agricultural region in Poland that is very susceptible to soil erosion processes. A high erosion risk of more than 10 tonnes per ha and year was assessed to occur on 13.6% (646 ha) of the agricultural areas within the investigated plot. Further 7.8% (372 ha) of agricultural land is threaten by a medium risk of 5-10 tonnes per ha and year. Such a spatial information about areas of high or medium soil erosion risk are crucial for the development of strategies for the protection of soils. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. Risk assessment of desertification using GIS in parts of Mond Basin, Southern Iran

    International Nuclear Information System (INIS)

    Masoudi, M.; Asrari, E.

    2009-01-01

    The present paper attempts to evolve a new model by considering various indicators of different types of land degradation desertification, namely water erosion, soil salinity, vegetation degradation, and lowering of ground water table. the Mond river basin, located centrally to this zone, has been selected as a test area to assess the risk and kind of desertification. For this purpose two sub basins of the Payab and Quareh Aghaj have been chosen for detailed study. The thresholds for the severity classes of indicators have been established and then the hazards map for each indicator of types of desertification has been prepared in a GIS. The risk maps of water erosion, soil salinization, lowering of water table, vegetation degradation have been produced for each of the two sub basins. It was possible to distinguish the areas under actual risk from areas under potential risk of desertification types. Also areas under potential risk are classified to subclasses with different probability level to show a statistical picture of risk in future. (Author) 3 refs.

  5. The influence of cover crops and tillage on actual and potential soil erosion in an olive grove

    Science.gov (United States)

    Sastre, Blanca; Bienes, Ramón; García-Díaz, Andrés; Panagopoulos, Thomas; José Marqués, Maria

    2014-05-01

    The study was carried out in an olive grove in central Spain (South of Madrid; Tagus River Basin). In this semi-arid zone, the annual mean temperature is 13.8 ºC and the annual precipitation is 395 mm. Olive groves are planted in an erosion prone area due to steep slopes up to 15%. Soil is classified as Typic Haploxerept with clay loam texture. The land studied was formerly a vineyard, but it was replaced by the studied olive grove in 2004. It covers approximately 3 ha and olive trees are planted every 6 x 7 metres. They were usually managed by tillage to decrease weed competition. This conventional practice results in a wide surface of bare soil prone to erosion processes. In the long term soil degradation may lead to increase the desertification risk in the area. Storms have important consequences in this shallow and vulnerable soil, as more than 90 Mg ha-1 have been measured after one day with 40 mm of rainfall. In order to avoid this situation, cover crops between the olive trees were planted three years ago: sainfoin (Onobrychis viciifolia), barley (Hordeum vulgare), and purple false brome (Brachypodium distachyon), and they were compared with annual spontaneous vegetation after a minimum tillage treatment (ASV). The results regarding erosion control were positive. We observed (Oct. 2012/Sept. 2013) annual soil loss up to 11 Mg ha-1 in ASV, but this figure was reduced in the sown covers, being 8 Mg ha-1 in sainfoin treatment, 3,7 Mg ha-1 in barley treatment, and only 1,5 Mg ha-1 in false brome treatment. Those results are used to predict the risk of erosion in long term. Moreover, soil organic carbon (SOC) increased with treatments, this is significant as it reduces soil erodibility. The increases were found both in topsoil (up to 5 cm) and more in depth, in the root zone (from 5 to 10 cm depth). From higher to lower SOC values we found the false brome (1.05%), barley (0.92%), ASV (0.79%) and sainfoin (0.71%) regarding topsoil. In the root zone (5-10 cm depth

  6. Intravesical midurethral sling mesh erosion secondary to transvaginal mesh reconstructive surgery

    Directory of Open Access Journals (Sweden)

    Sukanda Bin Jaili

    2015-05-01

    Conclusion: Repeated vaginal reconstructive surgery may jeopardize a primary mesh or sling, and pose a high risk of mesh erosion, which may be delayed for several years. Removal of the mesh erosion and bladder repair are feasible pervaginally with good outcome.

  7. A terminological matter: paragenesis, antigravitative erosion or antigravitational erosion ?

    Directory of Open Access Journals (Sweden)

    Pasini G.

    2009-07-01

    Full Text Available In the speleological literature three terms are utilized to designate the “ascending erosion”: paragenesis (= paragénésis, coined in1968, antigravitative erosion (= erosione antigravitativa, coined in 1966 and antigravitational erosion (wrong English translation ofthe Italian term erosione antigravitativa, utilized later on. The term paragenesis should be abandoned because of the priority of theterm erosione antigravitativa - on the ground of the “law of priority” – and because of its ambiguous etimology. On the other hand,the term antigravitational erosion should be forsaken in favour of the term antigravitative erosion, given the meaning that the termsgravitation and gravity have in Physics. Therefore, to designate the phenomenon of the “ascending erosion” there would be nothingleft but the term antigravitative erosion.The antigravitative erosion process and its recognizability are illustrated.Examples of caves with evident antigravitative erosion phenomena, developed in different karstifiable rocks and in several partsof the world, are given.It is recalled that the antigravitative erosion is a phenomenon well-known since 1942 and widely proven and supported, and that it isrelatively easy – in many cases - to recognize the antigravitative origin of karstic passages.It is stressed that the antigravitative erosion is an important phenomenon, exclusive of the karstic caves and unique in nature.

  8. Dental Erosion in Children with Gastroesophageal Reflux Disease.

    Science.gov (United States)

    De Oliveira, Patricia Alves Drummond; Paiva, Saul Martins; De Abreu, Mauro Henrique Nogueira Guimarães; Auad, Sheyla Márcia

    2016-01-01

    The purpose of this study was to investigate the impact of gastroesophageal reflux disease (GERD) on dental erosion (DE) in children and analyze the association between dental erosion and diet, oral hygiene, and sociodemographic characteristics. This case-control study encompassed 43 two- to 14-year-olds diagnosed positive for GERD by the 24-hour pH monitoring, paired by age group with 136 healthy controls, in Belo Horizonte, Minas Gerais, Brazil. DE was assessed by one calibrated examiner using the O'Sullivan index. A questionnaire was self-administered by parents collecting information regarding sociodemographics, oral hygiene, and dietary habits. Dental erosion experience was compared between the groups, and a stratified analysis was performed (PDental erosion was diagnosed in 10.6 percent (N equals 19) of all the children; 25.6 percent (N equals 11) of GERD children and 5.9 percent (N equals eight) of children without GERD, P=0.001). Dental erosion was not associated with dietary consumption or sociodemographic characteristics in both groups (P≥0.05). Children who used adult toothpaste had a 5.79 higher chance of having dental erosion in the group with GERD. Children diagnosed with gastroesophageal reflux disease were at an increased risk of having dental erosion when compared to healthy subjects; among the GERD children, dental erosion was associated with the use of adult toothpaste.

  9. Modeling the fluid/soil interface erosion in the Hole Erosion Test

    Directory of Open Access Journals (Sweden)

    Kissi B.

    2012-07-01

    Full Text Available Soil erosion is a complex phenomenon which yields at its final stage to insidious fluid leakages under the hydraulic infrastructures known as piping and which are the main cause of their rupture. The Hole Erosion Test is commonly used to quantify the rate of piping erosion. In this work, The Hole Erosion Test is modelled by using Fluent software package. The aim is to predict the erosion rate of soil during the hole erosion test. The renormalization group theory – based k–ε turbulence model equations are used. This modelling makes it possible describing the effect of the clay concentration in flowing water on erosion. Unlike the usual one dimensional models, the proposed modelling shows that erosion is not uniform erosion along the hole length. In particular, the concentration of clay is found to increase noticeably the erosion rate.

  10. Effect of corrosion protective coatings on compressor blades affected by different erosive exposures

    International Nuclear Information System (INIS)

    Happle, T.W.

    1989-01-01

    It was the task of this dissertation to examine and to classify the inorganically bonded aluminum coatings with regard to their suitability as a coating for compressor blades for stationary gas turbines and aerojet engines. Industrial aluminum coatings bonded inorganically were used for the tests. Comparative examinations were done with diffusion-deposited aluminum layers as well as with aluminum layers precipitated electrolytically, and with modified inorganically bonded aluminum coatings (with additional TiN protective coating). The examination program was subdivided into two main tasks: Suitability tests and examination of corrosion fatigue. The suitability tests covered corrosion examinations (with salt spray and intermittent immersion tests), electrochemically controlled corrosion assessments (pitting corrosion behavior) and erosion assessments (erosive and abrasive wear tests). Experimental material was mainly the commercial compressor blade steel X20Cr13, and sample tests were carried out with the higher-strength steel X10CrNiMoV12 2 2. For the practical examination of the erosion resistance of the aluminum coatings, it was required to develop an erosion testing method. It was designed as an erosive and abrasive wear testing method with solid-face fluidized bed. The testing method makes it possible to pre-set all relevant quantities which influence the erosive and abrasive wear. (orig./MM) [de

  11. Impact of night-shift work on the prevalence of erosive esophagitis in shipyard male workers.

    Science.gov (United States)

    Chung, Tae Heum; Lee, Jiho; Kim, Moon Chan

    2016-08-01

    Whether night-shift work is a risk factor for gastroesophageal reflux disease is controversial. The aim of this study was to investigate the association between night-shift work and other factors, and erosive esophagitis. A cross-sectional study with 6040 male shipyard workers was performed. Esophagogastroduodenoscopic examination and a survey about night-shift work status, lifestyle, medical history, educational status, and marital status were conducted in all workers. The odds ratios of erosive esophagitis according to night-shift work status were calculated by using the logistic regression model. The prevalence of erosive esophagitis increased in the night-shift workers [odds ratio, 95 % confidence interval: 1.41 (1.03-1.94)]. According to multiple logistic regression models, night-shift work, obesity, smoking, and alcohol consumption of ≥140 g/week were significant risk factors for erosive esophagitis. By contrast, Helicobacter pylori infection was negatively associated with erosive esophagitis. Night-shift work is suggested to be a risk factor for erosive esophagitis. Avoidance of night-shift work and lifestyle modification should be considered for prevention and management of gastroesophageal reflux disease.

  12. Prevalence of Dental Erosion among the Young Regular Swimmers in Kaunas, Lithuania.

    Science.gov (United States)

    Zebrauskas, Andrius; Birskute, Ruta; Maciulskiene, Vita

    2014-04-01

    To determine prevalence of dental erosion among competitive swimmers in Kaunas, the second largest city in Lithuania. The study was designed as a cross-sectional survey, with a questionnaire and clinical examination protocols. The participants were 12 - 25 year-old swimmers regularly practicing in the swimming pools of Kaunas. Of the total of 132 participants there were 76 (12 - 17 year-old) and 56 (18 - 25 year-old) individuals; in Groups 1 and 2, respectively. Participants were examined for dental erosion, using a portable dental unit equipped with fibre-optic light, compressed air and suction, and standard dental instruments for oral inspection. Lussi index was applied for recording dental erosion. The completed questionnaires focused on the common erosion risk factors were returned by all participants. Dental erosion was found in 25% of the 12 - 17 year-olds, and in 50% of 18 - 25 years-olds. Mean value of the surfaces with erosion was 6.31 (SD 4.37). All eroded surfaces were evaluated as grade 1. Swimming training duration and the participants' age correlated positively (Kendall correlation, r = 0.65, P dental erosion and the analyzed risk factors (gastroesophageal reflux disease, frequent vomiting, dry mouth, regular intake of acidic medicines, carbonated drinks) was found in both study groups. Prevalence of dental erosion of very low degree was high among the regular swimmers in Kaunas, and was significantly related to swimmers' age.

  13. Utility of combined high-resolution bone SPECT and MRI for the identification of rheumatoid arthritis patients with high-risk for erosive progression

    Energy Technology Data Exchange (ETDEWEB)

    Buchbender, Christian, E-mail: christian.buchbender@med.uni-duesseldorf.de [Univ Dusseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, Moorenstr. 5, D-40225 Dusseldorf (Germany); Sewerin, Philipp, E-mail: philipp.sewerin@med.uni-duesseldorf.de [Univ Dusseldorf, Medical Faculty, Department of Rheumatology, Moorenstr. 5, D-40225 Dusseldorf (Germany); Mattes-György, Katalin, E-mail: katalin.mattes@med.uni-duesseldorf.de [Univ Dusseldorf, Medical Faculty, Department of Nuclear Medicine, Moorenstr. 5, D-40225 Dusseldorf (Germany); Miese, Falk, E-mail: falk.miese@med.uni-duesseldorf.de [Univ Dusseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, Moorenstr. 5, D-40225 Dusseldorf (Germany); Wittsack, Hans-Joerg, E-mail: hans-joerg.wittsack@med.uni-duesseldorf.de [Univ Dusseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, Moorenstr. 5, D-40225 Dusseldorf (Germany); Specker, Christof, E-mail: c.specker@kliniken-essen-sued.de [Department of Rheumatology and Clinical Immunology, Kliniken Essen-Sud, Propsteistrasse 2, D-45239 Essen (Germany); Antoch, Gerald, E-mail: antoch@med.uni-duesseldorf.de [Univ Dusseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, Moorenstr. 5, D-40225 Dusseldorf (Germany); Müller, Hans-Wilhelm, E-mail: HansW.Mueller@med.uni-duesseldorf.de [Univ Dusseldorf, Medical Faculty, Department of Nuclear Medicine, Moorenstr. 5, D-40225 Dusseldorf (Germany); Schneider, Matthias, E-mail: matthias.schneider@med.uni-duesseldorf.de [Univ Dusseldorf, Medical Faculty, Department of Rheumatology, Moorenstr. 5, D-40225 Dusseldorf (Germany); Scherer, Axel, E-mail: scherer@med.uni-duesseldorf.de [Univ Dusseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, Moorenstr. 5, D-40225 Dusseldorf (Germany); Ostendorf, Benedikt, E-mail: ostendorf@med.uni-duesseldorf.de [Univ Dusseldorf, Medical Faculty, Department of Rheumatology, Moorenstr. 5, D-40225 Dusseldorf (Germany)

    2013-02-15

    Objectives: To evaluate the utility of sequentially acquired, post hoc fused, magnetic resonance imaging (MRI) and multi-pinhole single photon emission computed tomography (MPH-SPECT) with technetium-99m-labeled disphosphonates (Tc99m-DPD) for the identification of finger joints with later erosive progression in early rheumatoid arthritis (ERA) patients. Methods: Ten consecutive ERA patients prospectively underwent MPH-SPECT and MRI of metacarpophalangeal (MCP) joints prior to and after 6 months methotrexate therapy. Tc99m-DPD uptake was measured at proximal and distal MCP sites using regional analysis. The course of joint pathologies was scored according to the Rheumatoid Arthritis MRI Score (RAMRIS) criteria. Results: The frequency of increased Tc99m-DPD uptake, synovitis and bone marrow edemadecreased under MTX therapy; but the number of bone erosions increased. Joints with progressive and new erosions on follow-up had a higher baseline Tc99m-DPD uptake (2.64 ± 1.23 vs. 1.43 ± 0.91) (p = 0.02). Conclusions: Joints with erosive progression are characterized by an early increased Tc99m-DPD uptake, even in absence of MRI bone pathologies. Tc99m-DPD MPH-SPECT might thus be of additional value to morphological MRI for the identification of RA patients with a high risk for erosive progression.

  14. Terraced landscape: from an old best practice to a rising land abandoned-related soil erosion risk

    Science.gov (United States)

    Tarolli, Paolo; Preti, Federico; Romano, Nunzio

    2013-04-01

    Among the most evident landscape signatures of human fingerprint during the Holocene, the terraces related to agricultural activities deserve a great importance. Landscape terracing probably represents one of the oldest best practice primarily for crop production, but also for mitigating soil erosion and stabilizing hillslopes in landforms dominated by steep slopes. This technique is widely used in various parts of the world even under different environmental conditions. In some zones, terraced landscapes, because of their history and locations, can also be considered a historical heritage and a sort of "cultural landscape" to preserve, an absolutely value for tourism. To preserve their original role of soil erosion prevention, terraces should be properly designed built according to specific and sustainable engineering rules. Then, their maintenance is the most critical issue to deal with. It is well known from literature that terraced landscapes subject to abandonment would result in an increasing of terrace failure and related land degradation. If not maintained, a progressively increasing of gully erosion affects the structure of the walls. The results of this process is the increasing of connectivity and runoff. During the last few years and partly because of changing in the society perspective and migration toward metropolitan areas, some Countries have been affected by a serious and wider land abandonment with an increasing of soil erosion and derived landslide risk. Italy is one example. In this work, we consider three typical case studies of a terraced landscape where the lack of maintenance characterizing the last few years, increased the landslide risk with several problems to the population. The first case study is located along the renowed "Amalfi Coast" (a portion of land located near Salerno, southern Italy), the second is placed in the north of Toscana (a region located in Central Italy), and the third one along the so-called "Cinque Terre" (a region

  15. THE WATER FROM NATURE AND THE EROSION PROCESS

    Directory of Open Access Journals (Sweden)

    G. PANDI

    2015-03-01

    Full Text Available The water from nature and the erosion process. Studying earth's surface erosion process is necessary for practical reasons. The theoretical approach requires knowledge of the alluvial system’s structure and operation as the cascade sequence of fluvial system’s mass and energy. Geosystem research methodology requires that the water energy and the role of adjacent surface must be expressed. The expression of water power can be grouped according to the shape of movement and action in the basin. A particular, important case is the energy variation in a basin-slope. An important role in energy expressions is considering the existence in nature of biphasic fluid - water as dispersion phase and solid particles as dispersed phase. The role of the adjacent surface is taken into account by using the erosion resistance indicator, which is calculated using the indicator of geological resistance and the indicator of plant protection. The evolution of natural systems, therefore of river basins too, leads to energy diminishing, thus affecting their dynamic balance. This can be expressed using the concept of entropy. Although erosion processes are usual natural phenomena for the evolution of river basins, they induce significant risks in certain circumstances. Depending on the circulated water energies, water basins can be ranked in terms of potential risks.

  16. Application of SEAGIS model for assessing risks of erosion in the watershed of Lake hills of M'Richet el Anze (Bargou, Siliana)

    International Nuclear Information System (INIS)

    Touihri, Nouha

    2013-01-01

    Water erosion is a major problem in the world; it results from the agricultural intensification, the climatic variations, the nature and use of soil. The study of erosion risk requires the understanding the factor from which he is influenced. So it facilitates the decision-making regarding the proper management and restoration of soils. Several studies on erosion in Tunisia have been made. The present study aims to develop an easy method, based on the integration of map data (administrative boundaries, soil layers) and statistical data (rainfall) in a GIS for the identification and mapping of vulnerable soils to erosion. The methodology used, was to retain and study the parameters of the relevant factors influencing the phenomenon (the erosivite of rainfall, the topographic index, the occupation of grounds and the soil erodibility). Then after a consolidation of individual parameters of these different factors, they have been folded under the ArcView GIS 3.2a as a model of vulnerability of soils previously established. The model established by a tree of entrance. He allows the crossing of five factors(mailmen) (the erosivite of the rain (R), pedological card(map) ( K ), card(map) of activity(occupation) of ground ( C ), digital model of the ground ( MNT), the factor(mailman) of arrangement(development) ( P )) in the tree of entered and this led to the realization of the erosion hazard map. Then the result of the erosion hazard is crossed to determine the soil loss map. The results were used to locate five classes of vulnerabilities of soil erosion (very low, low, medium, high and very high). These results are used to simulate water conservation management scenarios end the fight against erosion.

  17. A tool for rapid assessment of erosion risk to support decision-making and policy development at the Ngenge watershed in Uganda

    NARCIS (Netherlands)

    Mutekanga, F.P.; Visser, S.M.; Stroosnijder, L.

    2010-01-01

    This study tests a rapid, user-friendly method for assessing changes in erosion risk, which yields information to aid policy development and decision-making for sustainable natural resources management. There is currently a lack of timely, up-to-date and current information to support policy

  18. Numerical modelling of concentrated leak erosion during Hole Erosion Tests

    OpenAIRE

    Mercier, F.; Bonelli, S.; Golay, F.; Anselmet, F.; Philippe, P.; Borghi, R.

    2015-01-01

    This study focuses on the numerical modelling of concentrated leak erosion of a cohesive soil by a turbulent flow in axisymmetrical geometry, with application to the Hole Erosion Test (HET). The numerical model is based on adaptive remeshing of the water/soil interface to ensure accurate description of the mechanical phenomena occurring near the soil/water interface. The erosion law governing the interface motion is based on two erosion parameters: the critical shear stress and the erosion co...

  19. Effect of endurance training on dental erosion, caries, and saliva.

    Science.gov (United States)

    Frese, C; Frese, F; Kuhlmann, S; Saure, D; Reljic, D; Staehle, H J; Wolff, D

    2015-06-01

    The aim of this investigation was to give insights into the impact of endurance training on oral health, with regard to tooth erosion, caries, and salivary parameters. The study included 35 triathletes and 35 non-exercising controls. The clinical investigation comprised oral examination, assessment of oral status with special regard to caries and erosion, saliva testing during inactivity, and a self-administered questionnaire about eating, drinking, and oral hygiene behavior. In addition, athletes were asked about their training habits and intake of beverages and sports nutrition. For saliva assessment during exercise, a subsample of n = 15 athletes volunteered in an incremental running field test (IRFT). Athletes showed an increased risk for dental erosion (P = 0.001). No differences were observed with regard to caries prevalence and salivary parameters measured during inactivity between athletes and controls. Among athletes, a significant correlation was found between caries prevalence and the cumulative weekly training time (r = 0.347, P = 0.04). In athletes after IRFT and at maximum workload, saliva flow rates decreased (P = 0.001 stimulated; P = 0.01 unstimulated) and saliva pH increased significantly (P = 0.003). Higher risk for dental erosions, exercise-dependent caries risk, and load-dependent changes in saliva parameters point out the need for risk-adapted preventive dental concepts in the field of sports dentistry. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  20. Dental erosion and its association with diet in Libyan schoolchildren.

    Science.gov (United States)

    Huew, R; Waterhouse, P J; Moynihan, P J; Kometa, S; Maguire, A

    2011-10-01

    To investigate any association between dental erosion and its potential dietary risk factors in a group of schoolchildren in Benghazi, Libya. A cross-sectional observational study. A random sample of 12-year-old schoolchildren in 36 randomly selected schools completed a questionnaire to provide dietary data and underwent dental examination. Dental erosion was assessed using UK National Diet and Nutrition Survey (2000) criteria. Associations between erosion and dietary variables under study were investigated through processes of bivariate and multivariate analyses. Of 791 schoolchildren dentally examined, 40.8% had dental erosion; erosion into enamel affecting 32.5%, into dentine affecting 8% and into pulp affecting 0.3% of subjects. Bivariate analysis showed frequency of fruit-based sugary drink intake was statistically significantly and positively associated with erosion (p=0.006, Odds Ratio; 1.498, 95% CI; 1.124, 1.996) as was the length of time taken to consume acidic drinks (p≠0.005, Odds Ratio; 1.593, 95%CI; 1.161, 2.186). Additionally, multivariate analysis showed frequency of consumption of fruit other than bananas, sugared tea with milk and flavoured milk to also be positively associated with erosion (p=dental erosion.

  1. Soil erosion assessment using geographical information system (GIS) and remote sensing (RS) study from Ankara-Guvenc Basin, Turkey.

    Science.gov (United States)

    Dengiz, Orhan; Yakupoglu, Tugrul; Baskan, Oguz

    2009-05-01

    The objective of this research was to assess vulnerable soil erosion risk with qualitative approach using GIS in Ankara-Guvenc Basin. The study area is located about 44 km north of Ankara and covers 17.5 km2. The selected theme layers of this model include topographic factor, soil factors (depth, texture, impermeable horizon) and land use. Slope layer and land use-land cover data were prepared by using DEM and Landsat-TM satellite image. According to land use classification, the most common land use type and land cover are rangeland (50.5%) then, rainfed (36.4%), week forest land (3.2%), irrigated land (0.7%) and other various lands (rock out crop and lake) (9.2%). Each land characteristic is also considered as a thematic layer in geographical information systems (GIS) process. After combination of the layers, soil erosion risk map was produced. The results showed that 44.4% of the study area is at high soil erosion risk, whereas 42% of the study area is insignificantly and slightly susceptible to erosion risk. In addition, it was found that only 12.6% of the total area is moderately susceptible to erosion risk. Furthermore, conservation land management measures were also suggested for moderate, high and very high erosion risk areas in Ankara-Guvenc Basin.

  2. The extreme risk of personal data breaches and the erosion of privacy

    Science.gov (United States)

    Wheatley, Spencer; Maillart, Thomas; Sornette, Didier

    2016-01-01

    Personal data breaches from organisations, enabling mass identity fraud, constitute an extreme risk. This risk worsens daily as an ever-growing amount of personal data are stored by organisations and on-line, and the attack surface surrounding this data becomes larger and harder to secure. Further, breached information is distributed and accumulates in the hands of cyber criminals, thus driving a cumulative erosion of privacy. Statistical modeling of breach data from 2000 through 2015 provides insights into this risk: A current maximum breach size of about 200 million is detected, and is expected to grow by fifty percent over the next five years. The breach sizes are found to be well modeled by an extremely heavy tailed truncated Pareto distribution, with tail exponent parameter decreasing linearly from 0.57 in 2007 to 0.37 in 2015. With this current model, given a breach contains above fifty thousand items, there is a ten percent probability of exceeding ten million. A size effect is unearthed where both the frequency and severity of breaches scale with organisation size like s0.6. Projections indicate that the total amount of breached information is expected to double from two to four billion items within the next five years, eclipsing the population of users of the Internet. This massive and uncontrolled dissemination of personal identities raises fundamental concerns about privacy.

  3. Power of resting echocardiographic measurements to classify pulmonary hypertension patients according to European society of cardiology exercise testing risk stratification cut-offs.

    Science.gov (United States)

    Rehman, Michaela B; Garcia, Rodrigue; Christiaens, Luc; Larrieu-Ardilouze, Elisa; Howard, Luke S; Nihoyannopoulos, Petros

    2018-04-15

    Right ventricular function is the major determinant of morbidity and mortality in pulmonary arterial hypertension (PAH). The ESC risk assessment strategy for PAH is based on clinical status, exercise testing, NTproBNP, imaging and haemodynamics but does not include right ventricular function. Our aims were to test the power of resting echocardiographic measurements to classify PAH patients according to ESC exercise testing risk stratification cut-offs and to determine if the classification power of echocardiographic parameters varied in chronic thrombo-embolic pulmonary hypertension (CTEPH). We prospectively and consecutively recruited 46 PAH patients and 42 CTEPH patients referred for cardio-pulmonary exercise testing and comprehensive transthoracic echocardiography. Exercise testing parameters analyzed were peak oxygen consumption, percentage of predicted maximal oxygen consumption and the slope of ventilation against carbon dioxide production. Receiver operator characteristic curves were used to determine the optimal diagnostic cut-off values of echocardiographic parameters for classifying the patients in intermediate or high risk category according to exercise testing. Measurements of right ventricular systolic function were the best for classifying in PAH (area under the curve 0.815 to 0.935). Measurements of right ventricular pressure overload (0.810 to 0.909) were optimal for classifying according to exercise testing in CTEPH. Measurements of left ventricular function were of no use in either group. Measurements of right ventricular systolic function can classify according to exercise testing risk stratification cut-offs in PAH. However, this is not the case in CTEPH where pressure overload, rather than right ventricular function seems to be linked to exercise performance. Copyright © 2018 Elsevier B.V. All rights reserved.

  4. Probabilistic estimation of dune erosion and coastal zone risk

    NARCIS (Netherlands)

    Li, F.

    2014-01-01

    Coastal erosion has gained global attention and has been studied for many decades. As a soft sea defence structure, coastal sandy dunes protect coastal zones all over the world, which usually are densely populated areas with tremendous economic value. The coastal zone of the Netherlands, one of the

  5. Relationships between soil erosion risk, soil use and soil properties in Mediterranean areas. A comparative study of three typical sceneries

    Science.gov (United States)

    Gil, Juan; Priego-Navas, Mercedes; Zavala, Lorena M.; Jordán, Antonio

    2013-04-01

    Generally, literature shows that the high variability of rainfall-induced soil erosion is related to climatic differences, relief, soil properties and land use. Very different runoff rates and soil loss values have been reported in Mediterranean cropped soils depending on soil management practices, but also in soils under natural vegetation types. OBJECTIVES The aim of this research is to study the relationships between soil erosion risk, soil use and soil properties in three typical Mediterranean areas from southern Spain: olive groves under conventional tillage, minimum tillage and no-till practices, and soils under natural vegetation. METHODS Rainfall simulation experiments have been carried out in order to assess the relationship between soil erosion risk, land use, soil management and soil properties in olive-cropped soils under different types of management and soils under natural vegetation type from Mediterranean areas in southern Spain RESULTS Results show that mean runoff rates decrease from 35% in olive grove soils under conventional tillage to 25% in olive (Olea europaea) grove soils with minimum tillage or no-till practices, and slightly over 22% in soils under natural vegetation. Moreover, considering the different vegetation types, runoff rates vary in a wide range, although runoff rates from soils under holm oak (Quercus rotundifolia), 25.70%, and marginal olive groves , 25.31%, are not significantly different. Results from soils under natural vegetation show that the properties and nature of the organic residues play a role in runoff characteristics, as runoff rates above 50% were observed in less than 10% of the rainfall simulations performed on soils with a organic layer. In contrast, more than half of runoff rates from bare soils reached or surpassed 50%. Quantitatively, average values for runoff water losses increase up to 2.5 times in unprotected soils. This is a key issue in the study area, where mean annual rainfall is above 600 mm

  6. Managing dental erosion.

    Science.gov (United States)

    Curtis, Donald A; Jayanetti, Jay; Chu, Raymond; Staninec, Michal

    2012-01-01

    The clinical signs of dental erosion are initially subtle, yet often progress because the patient remains asymptomatic, unaware and uninformed. Erosion typically works synergistically with abrasion and attrition to cause loss of tooth structure, making diagnosis and management complex. The purpose of this article is to outline clinical examples of patients with dental erosion that highlight the strategy of early identification, patient education and conservative restorative management. Dental erosion is defined as the pathologic chronic loss of dental hard tissues as a result of the chemical influence of exogenous or endogenous acids without bacterial involvement. Like caries or periodontal disease, erosion has a multifactorial etiology and requires a thorough history and examination for diagnosis. It also requires patient understanding and compliance for improved outcomes. Erosion can affect the loss of tooth structure in isolation of other cofactors, but most often works in synergy with abrasion and attrition in the loss of tooth structure (Table 1). Although erosion is thought to be an underlying etiology of dentin sensitivity, erosion and loss of tooth structure often occurs with few symptoms. The purpose of this article is threefold: first, to outline existing barriers that may limit early management of dental erosion. Second, to review the clinical assessment required to establish a diagnosis of erosion. And third, to outline clinical examples that review options to restore lost tooth structure. The authors have included illustrations they hope will be used to improve patient understanding and motivation in the early management of dental erosion.

  7. Prevalence of Dental Erosion among the Young Regular Swimmers in Kaunas, Lithuania

    Directory of Open Access Journals (Sweden)

    Andrius Zebrauskas

    2014-07-01

    Full Text Available Objectives: To determine prevalence of dental erosion among competitive swimmers in Kaunas, the second largest city in Lithuania. Material and Methods: The study was designed as a cross-sectional survey, with a questionnaire and clinical examination protocols. The participants were 12 - 25 year-old swimmers regularly practicing in the swimming pools of Kaunas. Of the total of 132 participants there were 76 (12 - 17 year-old and 56 (18 - 25 year-old individuals; in Groups 1 and 2, respectively. Participants were examined for dental erosion, using a portable dental unit equipped with fibre-optic light, compressed air and suction, and standard dental instruments for oral inspection. Lussi index was applied for recording dental erosion. The completed questionnaires focused on the common erosion risk factors were returned by all participants. Results: Dental erosion was found in 25% of the 12 - 17 year-olds, and in 50% of 18 - 25 years-olds. Mean value of the surfaces with erosion was 6.31 (SD 4.37. All eroded surfaces were evaluated as grade 1. Swimming training duration and the participants’ age correlated positively (Kendall correlation, r = 0.65, P < 0.001, meaning that older swimmers had practiced for longer period. No significant correlation between occurrence of dental erosion and the analyzed risk factors (gastroesophageal reflux disease, frequent vomiting, dry mouth, regular intake of acidic medicines, carbonated drinks was found in both study groups. Conclusions: Prevalence of dental erosion of very low degree was high among the regular swimmers in Kaunas, and was significantly related to swimmers’ age.

  8. Heel erosion and other interdigital disorders in dairy cows

    DEFF Research Database (Denmark)

    Enevoldsen, Carsten; Gröhn, Y.T.; Thysen, Iver

    1991-01-01

    Epidemiologic associations between variables obtainable from dairy cow records and the occurrence of heel erosion, interdigital dermatitis, and interdigital hyperplasia at claw trimmings were estimated with multivariable logistic regression analysis on data from 1170 and 542 cows in lactation 1...... and lactations 2 to 9, respectively. In the 17 herds, heel erosion, interdigital dermatitis, and hyperplasia occurred among 43.8, 4.5, and .9% of cows in lactation 1 and among 69.1, 7.6 and 5.9% of cows in lactations 2 to 9, respectively. Severity of heel erosion increased with parity, and risk increased...... with stage of lactation. Strong seasonal effects were present. Various combinations of veterinary treatments were associated with heel erosion and hyperplasia depending on parity, stage of lactation, and the presence of other claw disorders. In contrast, veterinary treatment had a protective effect...

  9. A lung cancer risk classifier comprising genome maintenance genes measured in normal bronchial epithelial cells.

    Science.gov (United States)

    Yeo, Jiyoun; Crawford, Erin L; Zhang, Xiaolu; Khuder, Sadik; Chen, Tian; Levin, Albert; Blomquist, Thomas M; Willey, James C

    2017-05-02

    Annual low dose CT (LDCT) screening of individuals at high demographic risk reduces lung cancer mortality by more than 20%. However, subjects selected for screening based on demographic criteria typically have less than a 10% lifetime risk for lung cancer. Thus, there is need for a biomarker that better stratifies subjects for LDCT screening. Toward this goal, we previously reported a lung cancer risk test (LCRT) biomarker comprising 14 genome-maintenance (GM) pathway genes measured in normal bronchial epithelial cells (NBEC) that accurately classified cancer (CA) from non-cancer (NC) subjects. The primary goal of the studies reported here was to optimize the LCRT biomarker for high specificity and ease of clinical implementation. Targeted competitive multiplex PCR amplicon libraries were prepared for next generation sequencing (NGS) analysis of transcript abundance at 68 sites among 33 GM target genes in NBEC specimens collected from a retrospective cohort of 120 subjects, including 61 CA cases and 59 NC controls. Genes were selected for analysis based on contribution to the previously reported LCRT biomarker and/or prior evidence for association with lung cancer risk. Linear discriminant analysis was used to identify the most accurate classifier suitable to stratify subjects for screening. After cross-validation, a model comprising expression values from 12 genes (CDKN1A, E2F1, ERCC1, ERCC4, ERCC5, GPX1, GSTP1, KEAP1, RB1, TP53, TP63, and XRCC1) and demographic factors age, gender, and pack-years smoking, had Receiver Operator Characteristic area under the curve (ROC AUC) of 0.975 (95% CI: 0.96-0.99). The overall classification accuracy was 93% (95% CI 88%-98%) with sensitivity 93.1%, specificity 92.9%, positive predictive value 93.1% and negative predictive value 93%. The ROC AUC for this classifier was significantly better (p < 0.0001) than the best model comprising demographic features alone. The LCRT biomarker reported here displayed high accuracy and ease

  10. Worldwide Experience with Erosion of the Magnetic Sphincter Augmentation Device.

    Science.gov (United States)

    Alicuben, Evan T; Bell, Reginald C W; Jobe, Blair A; Buckley, F P; Daniel Smith, C; Graybeal, Casey J; Lipham, John C

    2018-04-17

    The magnetic sphincter augmentation device continues to become a more common antireflux surgical option with low complication rates. Erosion into the esophagus is an important complication to recognize and is reported to occur at very low incidences (0.1-0.15%). Characterization of this complication remains limited. We aim to describe the worldwide experience with erosion of the magnetic sphincter augmentation device including presentation, techniques for removal, and possible risk factors. We reviewed data obtained from the device manufacturer Torax Medical, Inc., as well as the Manufacturer and User Facility Device Experience (MAUDE) database. The study period was from February 2007 through July 2017 and included all devices placed worldwide. In total, 9453 devices were placed and there were 29 reported cases of erosions. The median time to presentation of an erosion was 26 months with most occurring between 1 and 4 years after placement. The risk of erosion was 0.3% at 4 years after device implantation. Most patients experienced new-onset dysphagia prompting evaluation. Devices were successfully removed in all patients most commonly via an endoscopic removal of the eroded portion followed by a delayed laparoscopic removal of the remaining beads. At a median follow-up of 58 days post-removal, there were no complications and 24 patients have returned to baseline. Four patients reported ongoing mild dysphagia. Erosion of the LINX device is an important but rare complication to recognize that has been safely managed via minimally invasive approaches without long-term consequences.

  11. Implications of climate change scenarios for soil erosion potential in the USA

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, D L; White, D; Johnson, B [US EPA, Corvallis, OR (United States). Environmental Research Laboratory

    1993-07-01

    Atmospheric general circulation models (GCMs) project that increasing atmospheric concentrations of greenhouse gases may result in global changes in temperature and precipitation over the next 40-100 years. Equilibrium climate scenarios from four GCMs run under doubled CO[sub 2] conditions were examined for their effect on the climatic potential for sheet and rill erosion in the conterminous USA. Changes in the mean annual rainfall factor (R) in the Universal Soil Loss Equation (USLE) were calculated for each cropland, pastureland and rangeland sample point in the 1987 National Resources Inventory. Projected annual precipitation changes were assumed to be from differences in either storm frequency or storm intensity. With all other USLE factors held constant these changes in R translated to changes in the sheet and rill erosion national average of +2 to +16 per cent in croplands, -2 to +10 per cent in pasturelands and 5 to +22 per cent in rangelands under the eight scenarios. Land with erosion rates above the soil loss tolerance (T) level and land classified as highly erodible also increased slightly. These results show the range of sensitivity of soil erosion potential by water under projected climate change scenarios. However, actual changes in soil erosion could be mitigated by management practices, or possibly by increased crop growth and residue production under higher atmospheric CO[sub 2] concentrations.

  12. Dental caries and its association with diet and dental erosion in Libyan schoolchildren.

    Science.gov (United States)

    Huew, Rasmia; Waterhouse, Paula; Moynihan, Paula; Kometa, Simon; Maguire, Anne

    2012-01-01

    BACKGROUND. The change towards a more Westernised diet in Libya may increase the risk of caries and erosion in children. AIMS. To investigate any association between dental caries, dental erosion, and potential dietary risk factors in Libyan schoolchildren. METHODS. A random sample of 791 schoolchildren aged 12 years underwent dental examination for caries and erosion and completed a questionnaire to provide dietary data. Dental caries was assessed using the WHO (Oral Health Surveys: Basic Methods, 1997) criteria. Erosion was assessed using UK National Diet and Nutrition Survey (NDNS, Young People Aged 4-18 years. Volume 2: Report of the Oral Health Survey, 2000) criteria. Associations between caries and dietary variables were investigated through bivariate and multivariate analyses. RESULTS. Of the 791 12-year olds, 57.8% (457) had caries experience and 40.8% (323) had experience of erosion. One hundred and ninety-two subjects (42%) of the subjects with caries experience also had erosion, whilst 131 subjects (39.2%) of the 334 without caries had clinical signs of erosion (P = 0.464; OR, 1.123; 95% CI, 0.842, 1.497). There was no statistically significantly relationship between dental caries and dental erosion. Frequency of consumption of fruit-based sugared drinks was statistically significantly positively associated with experience of caries (P = 0.002). CONCLUSIONS. Dental caries experience was associated with frequency of consumption of sugared dietary items but not with dental erosion. © 2011 The Authors. International Journal of Paediatric Dentistry © 2011 BSPD, IAPD and Blackwell Publishing Ltd.

  13. Comparison of erosion and erosion control works in Macedonia, Serbia and Bulgaria

    Directory of Open Access Journals (Sweden)

    Ivan Blinkov

    2013-12-01

    Natural conditions in the Balkan countries contribute to the appearance of various erosion forms and the intensity of the erosion processes. Over the history of these countries, people who settled this region used the available natural resources to fill their needs (tree cutting, incorrect plugging, overgrazing, which contributed to soil erosion. Organized erosion control works in the Balkans started in the beginning of the 20th century (1905 in Bulgaria. The highest intensity of erosion control works were carried out during the period 1945 – 1990. Various erosion control works were launched. Bulgaria had a large anti-erosion afforestation, almost 1 million ha. Bulgaria's ecological river restoration approach has been in use for almost 50 years. Serbia contributed significant erosion and torrent control works on hilly agricultural areas. Specific screen barrages and afforestation on extremely dry areas are characteristic in Macedonia. A common characteristic for all countries is a high decrease in erosion control works in the last 20 years.

  14. Erosion-corrosion

    International Nuclear Information System (INIS)

    Aghili, B.

    1999-05-01

    A literature study on erosion-corrosion of pipings in the nuclear industry was performed. Occurred incidents are reviewed, and the mechanism driving the erosion-corrosion is described. Factors that influence the effect in negative or positive direction are treated, as well as programs for control and inspection. Finally, examples of failures from databases on erosion-corrosion are given in an attachment

  15. Alcohol consumption is associated with an increased risk of erosive esophagitis and Barrett's epithelium in Japanese men

    Directory of Open Access Journals (Sweden)

    Goto Ayumu

    2008-12-01

    Full Text Available Abstract Background Evidence regarding the association between alcohol consumption and the gastro-esophageal reflux disease (GERD spectrum has been conflicting. We examined the association between alcohol consumption and erosive esophagitis and Barrett's epithelium in Japanese men. Methods The study population comprised 463 men subjects who had undergone an upper endoscopy at the Gastroenterology Division of Yokohama City University Hospital between August 2005 and July 2006. The presence of erosive esophagitis and Barrett's epithelium was diagnosed based on the Los Angeles Classification and the Prague C and M Criteria, respectively. We divided the study population into four groups: never drinkers, light drinkers (less than 25.0 g of ethanol per day, moderate drinkers (25.0 to 50.0 g of ethanol per day, and heavy drinkers (more than 50.0 g of ethanol per day. A linear regression of the logistic regression analysis was used to analyze the dose-response trends. Results Compared with never drinkers, light drinkers (less than 25.0 g ethanol per day, moderate drinkers (25.0 to 50.0 g per day, and heavy drinkers (more than 50.0 g per day had ORs for erosive esophagitis of 1.110 (95% CI: 0.553 – 2.228, p = 0.7688, 1.880 (95% CI: 1.015 – 3.484, p = 0.0445 and 1.988 (95% CI: 1.120 – 3.534, p = 0.0190, respectively. These groups had ORs for Barrett's epithelium of 1.278 (95% CI: 0.752 – 2.170, p = 0.3643, 1.458 (95% CI: 0.873 – 2.433, p = 0.1500, and 1.912 (95% CI: 1.185 – 3.086, p = 0.0079, respectively. The odds ratios/grams (alcohol/day of dose response trends for erosive esophagitis and Barrett's epithelium were 1.015 (95% CI: 1.004–1.026, p = 0.0066 and 1.012 (95% CI: 1.003–1.021, p = 0.0079, respectively. Conclusion These findings suggest that alcohol consumption in Japanese men tends to be associated with an increased risk of erosive esophagitis and Barrett's epithelium.

  16. Characteristics of pulsed runoff-erosion events under typical rainstorms in a small watershed on the Loess Plateau of China.

    Science.gov (United States)

    Wu, Lei; Jiang, Jun; Li, Gou-Xia; Ma, Xiao-Yi

    2018-02-27

    The pulsed events of rainstorm erosion on the Loess Plateau are well-known, but little information is available concerning the characteristics of superficial soil erosion processes caused by heavy rainstorms at the watershed scale. This study statistically evaluated characteristics of pulsed runoff-erosion events based on 17 observed rainstorms from 1997-2010 in a small loess watershed on the Loess Plateau of China. Results show that: 1) Rainfall is the fundamental driving force of soil erosion on hillslopes, but the correlations of rainfall-runoff and rainfall-sediment in different rainstorms are often scattered due to infiltration-excess runoff and soil conservation measures. 2) Relationships between runoff and sediment for each rainstorm event can be regressed by linear, power, logarithmic and exponential functions. Cluster Analysis is helpful in classifying runoff-erosion events and formulating soil conservation strategies for rainstorm erosion. 3) Response characteristics of sediment yield are different in different levels of pulsed runoff-erosion events. Affected by rainfall intensity and duration, large changes may occur in the interactions between flow and sediment for different flood events. Results provide new insights into runoff-erosion processes and will assist soil conservation planning in the loess hilly region.

  17. Quantification Of Erosion Rates Of Agriculturally Used Soils By Artificial

    Science.gov (United States)

    Jha, Abhinand

    2010-05-01

    0.0.1 1. Introduction to soil erosion measurement by radionuclides Soil erosion by water, wind and tillage affects both agriculture and the natural environment. Studying this phenomenon would be one of the advancements in science. Soil erosion occurs worldwide and since the last two decades it has been a main topic of discussion all over the world. The use of environmental radionuclides such as 90Sr, 137Cs to study medium term soil erosion (40 yrs) started in the early 1990's. Using these new techniques better knowledge about erosion can be gained and this knowledge can be implemented for erosion risk management. The erosion and sedimentation study by using man-made and natural radioisotopes is a key technique, which has developed over the past 30 years. Fallout 137Cs and Cosmogenic 7Be are radionuclides that have been used to provide independent measurements of soil-erosion and sediment-deposition rates and patterns [1] [2] [3] [4]. Erosion measurements using radionuclides 137Cs, 7Be Caesium-137 from atmospheric nuclear-weapons tests in the 1950s and 1960s (Fig.1) is a unique tracer of erosion and sedimentation, since there are no natural sources of 137Cs. Unique events such as the Chernobyl accident in April 1986 caused regional dispersal of 137Cs that affects the total global deposition budget. This yearly pattern of fallout can be used to develop a chronology of deposition horizons in lakes, reservoirs, and floodplains. 137Cs can be easily measured by gamma spectroscopy. Using 137Cs is a fast and cheap method to study erosion-deposition processes compared to the traditional methods like silt bags. PIC Figure 1: Global 137Cs fallout (Modified from SAAS Bulletin 353, Part E, DDR, 1986) When 137Cs, 7Be reach the soil surface by wet and dry deposition, they are quickly and strongly adsorbed by ion exchange and are essentially non exchangeable in most environments. Each radionuclide is distributed differently in the soil because of differences in half-lives (30 yrs

  18. Dental erosion in 12-year-old school children living in Jakarta

    Science.gov (United States)

    Septalita, A.; Bahar, A.; Agustanti, A.; Rahardjo, A.; Maharani, D. A.; Rosalien, R.

    2017-08-01

    This study assesses the dental erosion status of 12-year-old Indonesian children and studies the determinants of dental erosion of these children. The survey was performed in 2016 with ethics approval. A multistage cluster proportional to size random sampling method was adopted to select 12-year-old children in 24 primary schools in Jakarta. The parents were asked to complete a self-administered questionnaire concerning their children’s diet and oral health habits. The children were examined by a single calibrated examiner. Detection of dental erosion followed basic erosive wear examination (BEWE) criteria. A total of 487 children participated in the survey. Most children (88%) had at least some signs of erosion (BEWE > 0), with dentin being involved in 50% of the cases (BEWE = 2). Dental erosion was significantly related to gender, the frequencies of citric tea consumption, parent’s dental knowledge, father’s education, and dental caries (OR = 3.148). The 12-year-old Indonesian school children who lived in Jakarta had signs of erosion, although severe erosion was not found. Screening programs should be provided to identify risk groups so early preventive measures can be taken.

  19. Separation of dry and wet periods from regular weather station data for the analysis of wind erosion risk

    DEFF Research Database (Denmark)

    Naeini, Mohammadali Saremi; Fister, Wolfgang; Heckrath, Goswin Johann

    importance, soil moisture content is often ignored in the analysis of wind data for wind erosion studies. The main reason most probably being the lack of soil moisture sensors in conventional climate stations. Soil moisture at a given point in time is determined by rain (e.g. rainfall amount, duration......), climate (e.g. air temperature, solar radiation, evaporation) and soil (e.g. infiltration rate, adhesion). The purpose of this study is to overcome the lack of soil moisture data for wind erosion risk assessment by developing a method to estimate the soil wetness based on easy available weather data......, such as daily precipitation, hourly/sub hourly ambient air temperature and hourly/sub hourly relative humidity. This new method was used to identify periods of wet and dry soil moisture conditions of a time series from 20 weather stations in Denmark. The length of the time series varied between 8 to 37 years...

  20. Prevalence of dental erosion in adolescent competitive swimmers exposed to gas-chlorinated swimming pool water.

    Science.gov (United States)

    Buczkowska-Radlińska, J; Łagocka, R; Kaczmarek, W; Górski, M; Nowicka, A

    2013-03-01

    The purpose of this study was to analyze the prevalence of dental erosion among competitive swimmers of the local swimming club in Szczecin, Poland, who train in closely monitored gas-chlorinated swimming pool water. The population for this survey consisted of a group of junior competitive swimmers who had been training for an average of 7 years, a group of senior competitive swimmers who had been training for an average of 10 years, and a group of recreational swimmers. All subjects underwent a clinical dental examination and responded to a questionnaire regarding aspects of dental erosion. In pool water samples, the concentration of calcium, magnesium, phosphate, sodium, and potassium ions and pH were determined. The degree of hydroxyapatite saturation was also calculated. Dental erosion was found in more than 26 % of the competitive swimmers and 10 % of the recreational swimmers. The lesions in competitive swimmers were on both the labial and palatal surfaces of the anterior teeth, whereas erosions in recreational swimmers developed exclusively on the palatal surfaces. Although the pH of the pool water was neutral, it was undersaturated with respect to hydroxyapatite. The factors that increase the risk of dental erosion include the duration of swimming and the amount of training. An increased risk of erosion may be related to undersaturation of pool water with hydroxyapatite components. To decrease the risk of erosion in competitive swimmers, the degree of dental hydroxyapatite saturation should be a controlled parameter in pool water.

  1. Application of support vector machine classifiers to preoperative risk stratification with myocardial perfusion scintigraphy

    International Nuclear Information System (INIS)

    Kasamatsu, Tomotaka; Hashimoto, Jun; Nakahara, Tadaki; Bai, Jingming; Kitamura, Naoto; Kubo, Atsushi; Iyatomi, Hitoshi; Ogawa, Koichi

    2008-01-01

    Myocardial perfusion single-photon emission computed tomography (SPECT) has been used for risk stratification before non-cardiac surgery. However, few authors have used mathematical models for evaluating the likelihood of perioperative cardiac events. This retrospective cohort study collected data of 1,351 patients referred for SPECT before non-cardiac surgery. We generated binary classifiers using support vector machine (SVM) and conventional linear models for predicting perioperative cardiac events. We used clinical and surgical risk, and SPECT findings as input data, and the occurrence of all and hard cardiac events as output data. The area under the receiver-operating characteristic curve (AUC) was calculated for assessing the prediction accuracy. The AUC values were 0.884 and 0.748 in the SVM and linear models, respectively in predicting all cardiac events with clinical and surgical risk, and SPECT variables. The values were 0.861 (SVM) and 0.677 (linear) when not using SPECT data as input. In hard events, the AUC values were 0.892 (SVM) and 0.864 (linear) with SPECT, and 0.867 (SVM) and 0.768 (linear) without SPECT. The SVM was superior to the linear model in risk stratification. We also found an incremental prognostic value of SPECT results over information about clinical and surgical risk. (author)

  2. Can control of soil erosion mitigate water pollution by sediments?

    Science.gov (United States)

    Rickson, R J

    2014-01-15

    The detrimental impact of sediment and associated pollutants on water quality is widely acknowledged, with many watercourses in the UK failing to meet the standard of 'good ecological status'. Catchment sediment budgets show that hill slope erosion processes can be significant sources of waterborne sediment, with rates of erosion likely to increase given predicted future weather patterns. However, linking on-site erosion rates with off-site impacts is complicated because of the limited data on soil erosion rates in the UK and the dynamic nature of the source-pathway-receptor continuum over space and time. Even so, soil erosion control measures are designed to reduce sediment production (source) and mobilisation/transport (pathway) on hill slopes, with consequent mitigation of pollution incidents in watercourses (receptors). The purpose of this paper is to review the scientific evidence of the effectiveness of erosion control measures used in the UK to reduce sediment loads of hill slope origin in watercourses. Although over 73 soil erosion mitigation measures have been identified from the literature, empirical data on erosion control effectiveness are limited. Baseline comparisons for the 18 measures where data do exist reveal erosion control effectiveness is highly variable over time and between study locations. Given the limitations of the evidence base in terms of geographical coverage and duration of monitoring, performance of the different measures cannot be extrapolated to other areas. This uncertainty in effectiveness has implications for implementing erosion/sediment risk reduction policies, where quantified targets are stipulated, as is the case in the EU Freshwater Fish and draft Soil Framework Directives. Also, demonstrating technical effectiveness of erosion control measures alone will not encourage uptake by land managers: quantifying the costs and benefits of adopting erosion mitigation is equally important, but these are uncertain and difficult to

  3. Application of IRS-1D data in water erosion features detection (case study: Nour roud catchment, Iran).

    Science.gov (United States)

    Solaimani, K; Amri, M A Hadian

    2008-08-01

    The aim of this study was capability of Indian Remote Sensing (IRS) data of 1D to detecting erosion features which were created from run-off. In this study, ability of PAN digital data of IRS-1D satellite was evaluated for extraction of erosion features in Nour-roud catchment located in Mazandaran province, Iran, using GIS techniques. Research method has based on supervised digital classification, using MLC algorithm and also visual interpretation, using PMU analysis and then these were evaluated and compared. Results indicated that opposite of digital classification, with overall accuracy 40.02% and kappa coefficient 31.35%, due to low spectral resolution; visual interpretation and classification, due to high spatial resolution (5.8 m), prepared classifying erosion features from this data, so that these features corresponded with the lithology, slope and hydrograph lines using GIS, so closely that one can consider their boundaries overlapped. Also field control showed that this data is relatively fit for using this method in investigation of erosion features and specially, can be applied to identify large erosion features.

  4. RUNOFF AND EROSION IN DIFFERENT (AGRO CLIMATOLOGICAL ZONES OF LATIN AMERICA AND PROPOSALS FOR SOIL AND WATER CONSERVATION SCENARIOS

    Directory of Open Access Journals (Sweden)

    Donald Gabriels

    2005-05-01

    Full Text Available Steeplands, when cleared from forests, are susceptible to erosion by rainfall and are prone toland degradation and desertification processes.The dominant factors affecting those erosion processes and hence the resulting runoff and soillosses are the aggressiveness of the rainfall during the successive plant growth stages, the soilcover-management, but also the topography (slope length and slope steepness. Depending onthe type of (agro climatological zone, the runoff water should either be limited and controlled(excess of water or should be enhanced and collected from the slope on the downslopecropping area if water is short (negative soil water balance.Examples are given of practical applications in Ecuador where alternative soil conservationscenarios are proposed in maize cultivation in small fields on steep slopes. Adding peas andbarley in the rotation of maize and beans resulted only in a slight decrease of the soil losses.Subdividing the fields into smaller parcels proved to give the best reduction in soil loss.Because the average slope steepness is high, erosion control measures such as contourploughing and strip cropping have only small effects.Erosion and its effect on productivity of a sorghum -livestock farming system are assessed onfour different areas in Venezuela with different levels of erosion. A Productivity Index (PIand an Erosion Risk Index (ERI were used to classify the lands for soil conservationpriorities and for alternative land uses. Intensive agriculture can be applied on slightly erodedsoil, whereas severely eroded soil can be used with special crops or agro-forestry. Semiintensiveagriculture is possible on moderately eroded soil.Reforestation of drylands in Chili requires understanding of the infiltration/runoff process inorder to determine dimensions of water harvesting systems. Infiltration processes in semi-aridregions of Chile were evaluated, using rainfall experiments and constant-head infiltrationmeasurements

  5. Erosive osteoarthritis: a more severe form of radiographic hand osteoarthritis rather than a distinct entity?

    Science.gov (United States)

    Marshall, Michelle; Nicholls, Elaine; Kwok, Wing-Yee; Peat, George; Kloppenburg, Margreet; van der Windt, Danielle; Myers, Helen; Dziedzic, Krysia

    2015-01-01

    Objectives To determine whether erosive osteoarthritis shares the same pattern of joint involvement and risk profile as increasing grades of non-erosive hand osteoarthritis. Methods Participants were from two population-based cohorts, aged ≥50 years, reporting hand symptoms in the previous month. Interphalangeal joints were assessed for erosive osteoarthritis (Verbruggen–Veys erosive or remodelled phase) and radiographic osteoarthritis (sliding cut-offs of K&L≥2, K&L≥3 and K&L=4). At the joint level, similarities in the frequency and pattern of erosive and non-erosive osteoarthritis were assessed by Spearman's rank correlation coefficients and generalised estimating equations. At the person level, individuals with erosive osteoarthritis were compared to those with non-erosive osteoarthritis using logistic regression, adjusted for age and gender (aOR), for the following exposures: family history, previous injury, overuse and metabolic factors (BMI, dyslipidaemia, hypertension, diabetes). Results In 1076 symptomatic participants the ranked frequency of involvement for erosive joints was comparable to joints with K&L≥3 and K&L=4 (r>0.95). Patterns of joint involvement in erosive osteoarthritis were strongest for symmetry (aOR=6.5; 95% CI 3.0 to 14.1), followed by row (2.0; 0.8 to 5.0) and ray (0.3; 0.0 to 2.5), which was similar to joints with K&L≥3 and K&L=4. Individuals with erosive osteoarthritis (n=80) had an increased risk of metabolic syndrome (2.7; 1.0 to 7.1), notably dyslipidaemia (4.7; 2.1 to 10.6) compared with non-erosive osteoarthritis classed K&L≥3 (n=193). Conclusions The similar frequency of radiographic joint involvement and patterning in erosive osteoarthritis and more severe non-erosive osteoarthritis is consistent with prevalent erosive osteoarthritis being a severe form of hand osteoarthritis rather than a distinct entity. Metabolic exposures, dyslipidaemia in particular, may be implicated in erosive osteoarthritis. PMID:24095935

  6. The global coastline dataset: the observed relation between erosion and sea-level rise

    Science.gov (United States)

    Donchyts, G.; Baart, F.; Luijendijk, A.; Hagenaars, G.

    2017-12-01

    Erosion of sandy coasts is considered one of the key risks of sea-level rise. Because sandy coastlines of the world are often highly populated, erosive coastline trends result in risk to populations and infrastructure. Most of our understanding of the relation between sea-level rise and coastal erosion is based on local or regional observations and generalizations of numerical and physical experiments. Until recently there was no reliable global scale assessment of the location of sandy coasts and their rate of erosion and accretion. Here we present the global coastline dataset that covers erosion indicators on a local scale with global coverage. The dataset uses our global coastline transects grid defined with an alongshore spacing of 250 m and a cross shore length extending 1 km seaward and 1 km landward. This grid matches up with pre-existing local grids where available. We present the latest results on validation of coastal-erosion trends (based on optical satellites) and classification of sandy versus non-sandy coasts. We show the relation between sea-level rise (based both on tide-gauges and multi-mission satellite altimetry) and observed erosion trends over the last decades, taking into account broken-coastline trends (for example due to nourishments).An interactive web application presents the publicly-accessible results using a backend based on Google Earth Engine. It allows both researchers and stakeholders to use objective estimates of coastline trends, particularly when authoritative sources are not available.

  7. A probabilistic approach to modeling postfire erosion after the 2009 Australian bushfires

    Science.gov (United States)

    P. R. Robichaud; W. J. Elliot; F. B. Pierson; D. E. Hall; C. A. Moffet

    2009-01-01

    Major concerns after bushfires and wildfires include increased flooding, erosion and debris flows due to loss of the protective forest floor layer, loss of water storage, and creation of water repellent soil conditions. To assist postfire assessment teams in their efforts to evaluate fire effects and make postfire treatment decisions, a web-based Erosion Risk...

  8. Modeling erosion of unsaturated compacted bentonite by groundwater flow; pinhole erosion test case

    International Nuclear Information System (INIS)

    Laurila, T.; Sane, P.; Olin, M.; Koskinen, K.

    2012-01-01

    Document available in extended abstract form only. Erosion of compacted clay material by water flow is a critical factor affecting the performance of radioactive waste confinement. Our emphasis in this work is the buffer of KBS-3V concept, proposed to be compacted MX-80 bentonite. Unsaturated erosion occurs during the saturation phase of the EBS, and the main quantity of interest is the total buffer mass carried away by a groundwater flow that induces erosion by forming piping channels near the buffer/rock interface. The purpose of this work is to provide modeling tools to support erosion experiments. Role of modeling is first to interpret experimental observations in terms of processes, and to estimate robustness of experimental results. Secondly, we seek to scale up results from the laboratory scale, particularly to time scales longer than those experimentally accessible. We have performed modeling and data analysis pertaining to tests of unsaturated clay erosion. Pinhole experiments were used to study this erosion case. The main differences to well-understood pinhole erosion tests are that the material is strongly swelling and that the water flow is not determined by the pressure head but by the total flux. Groundwater flow in the buffer is determined by the flux because pressure losses occur overwhelmingly in the surrounding rock, not in the piping channel. We formulate a simple model that links an effective solid diffusivity -based swelling model to erosion by flow on the solid/liquid interface. The swelling model is similar in concept to that developed at KTH, but simpler. Erosion in the model is caused by laminar flow in the pinhole, and happens in a narrow region at the solid/liquid interface where velocity and solid volume fraction overlap. The erosion model can be mapped to erosion by wall shear, and can thus be considered as extension of that classic erosion model. The main quantity defining the behavior of clay erosion in the model is the ratio of

  9. An investigation into the dental health of children with obesity: an analysis of dental erosion and caries status.

    Science.gov (United States)

    Tong, H J; Rudolf, M C J; Muyombwe, T; Duggal, M S; Balmer, R

    2014-06-01

    To investigate whether children with obesity experienced more erosion and caries than children with normal weight. This study involved children aged 7-15 years. The study and control group comprised 32 children with BMI > 98th centile and 32 healthy children with normal BMI-for-age, respectively. O'Sullivan Erosion Index and WHO Caries Index were used in the examination of erosion and caries, respectively. Stimulated salivary flow rate, buffering capacity, Streptococcus mutans and lactobacilli counts (CFU/ml) were evaluated. A cross-sectional questionnaire survey was employed to collect information on participant's demographic background, oral health history and habits, and utilisation of dental care services. Children with obesity were more likely to have erosion than healthy children (p erosion in terms of severity (p erosion (OR 0.32, 95 % CI 0.012-0.082). Gender had no effect on erosion. There were no statistically significant differences in the DMFT, saliva profiles or questionnaire responses between the groups. Children with obesity may have high risk of dental erosion, but do not necessarily have higher risk of dental caries than children with normal weight.

  10. Rainfall Erosivity in Europe

    DEFF Research Database (Denmark)

    Panagos, Panos; Ballabio, Cristiano; Borrelli, Pasquale

    2015-01-01

    Rainfall is one the main drivers of soil erosion. The erosive force of rainfall is expressed as rainfall erosivity. Rainfall erosivity considers the rainfall amount and intensity, and is most commonly expressed as the Rfactor in the USLE model and its revised version, RUSLE. At national...... and continental levels, the scarce availability of data obliges soil erosion modellers to estimate this factor based on rainfall data with only low temporal resolution (daily, monthly, annual averages). The purpose of this study is to assess rainfall erosivity in Europe in the form of the RUSLE R-factor, based...

  11. Aplicação dos modelos PESERA e MEDALUS para avaliação dos riscos de erosão do solo e de desertificação da bacia hidrográfica do Vale do Gaio Use of PESERA and MEDALUS models to assess soil erosion risks and land desertification in Vale do Gaio watershed

    Directory of Open Access Journals (Sweden)

    M. C. Gonçalves

    2010-01-01

    Full Text Available Neste trabalho testaram-se duas metodo­logias de avaliação dos riscos de erosão do solo e de desertificação na bacia hidrográfi­ca de Vale do Gaio (513 km², localizada no Alentejo. Os solos dominantes na bacia são os Cambissolos, Luvissolos e Regossolos. Os sistemas de Montado de Azinho e Sobro e os sistemas agrícolas de sequeiro domi­nam, por sua vez, a ocupação dos solos. O risco de erosão foi avaliado por estimativas das perdas do solo por erosão hídrica, atra­vés do modelo PESERA. As áreas em risco de desertificação foram determinadas com base na metodologia MEDALUS. As três classes mais representativas de perdas do solo por erosão hídrica, com base nos dados meteorológicos de 2001-2006, foram: In this study two methodologies were tested to assess soil erosion and land deserti­fication risks in Vale do Gaio watershed (513 km², located in the Alentejo region. Cambisols, Luvisols, and Regosols are the dominant soils in the watershed. Oak tree Mediterranean woodland, Agricultural crops and pastures are the major land uses. Soil erosion risks were assessed by estimating soil loss by water erosion with the PESERA model. Land area at risk of desertification was determined based on the MEDALUS methodology. Based on meteorological data from the period 2001-2006, the three most representative classes of soil loss by water erosion were: <0.5 t/ha/year in 32.1% of the area; 5-10 t/ha/year in 23.3% of the area; and 10-20 t/ha/year in 16.9% of the area. Considering the same time period, the land area at risk of desertification was classified: 1.8% as none threatened; 3.9% as potential; 68.4% as fragile; and 25.9% as critical to desertification.

  12. Water erosion susceptibility mapping by applying Stochastic Gradient Treeboost to the Imera Meridionale River Basin (Sicily, Italy)

    Science.gov (United States)

    Angileri, Silvia Eleonora; Conoscenti, Christian; Hochschild, Volker; Märker, Michael; Rotigliano, Edoardo; Agnesi, Valerio

    2016-06-01

    Soil erosion by water constitutes a serious problem affecting various countries. In the last few years, a number of studies have adopted statistical approaches for erosion susceptibility zonation. In this study, the Stochastic Gradient Treeboost (SGT) was tested as a multivariate statistical tool for exploring, analyzing and predicting the spatial occurrence of rill-interrill erosion and gully erosion. This technique implements the stochastic gradient boosting algorithm with a tree-based method. The study area is a 9.5 km2 river catchment located in central-northern Sicily (Italy), where water erosion processes are prevalent, and affect the agricultural productivity of local communities. In order to model soil erosion by water, the spatial distribution of landforms due to rill-interrill and gully erosion was mapped and 12 environmental variables were selected as predictors. Four calibration and four validation subsets were obtained by randomly extracting sets of negative cases, both for rill-interrill erosion and gully erosion models. The results of validation, based on receiving operating characteristic (ROC) curves, showed excellent to outstanding accuracies of the models, and thus a high prediction skill. Moreover, SGT allowed us to explore the relationships between erosion landforms and predictors. A different suite of predictor variables was found to be important for the two models. Elevation, aspect, landform classification and land-use are the main controlling factors for rill-interrill erosion, whilst the stream power index, plan curvature and the topographic wetness index were the most important independent variables for gullies. Finally, an ROC plot analysis made it possible to define a threshold value to classify cells according to the presence/absence of the two erosion processes. Hence, by heuristically combining the resulting rill-interrill erosion and gully erosion susceptibility maps, an integrated water erosion susceptibility map was created. The

  13. Estimation of Soil Erosion Dynamics in the Koshi Basin Using GIS and Remote Sensing to Assess Priority Areas for Conservation.

    Science.gov (United States)

    Uddin, Kabir; Murthy, M S R; Wahid, Shahriar M; Matin, Mir A

    2016-01-01

    High levels of water-induced erosion in the transboundary Himalayan river basins are contributing to substantial changes in basin hydrology and inundation. Basin-wide information on erosion dynamics is needed for conservation planning, but field-based studies are limited. This study used remote sensing (RS) data and a geographic information system (GIS) to estimate the spatial distribution of soil erosion across the entire Koshi basin, to identify changes between 1990 and 2010, and to develop a conservation priority map. The revised universal soil loss equation (RUSLE) was used in an ArcGIS environment with rainfall erosivity, soil erodibility, slope length and steepness, cover-management, and support practice factors as primary parameters. The estimated annual erosion from the basin was around 40 million tonnes (40 million tonnes in 1990 and 42 million tonnes in 2010). The results were within the range of reported levels derived from isolated plot measurements and model estimates. Erosion risk was divided into eight classes from very low to extremely high and mapped to show the spatial pattern of soil erosion risk in the basin in 1990 and 2010. The erosion risk class remained unchanged between 1990 and 2010 in close to 87% of the study area, but increased over 9.0% of the area and decreased over 3.8%, indicating an overall worsening of the situation. Areas with a high and increasing risk of erosion were identified as priority areas for conservation. The study provides the first assessment of erosion dynamics at the basin level and provides a basis for identifying conservation priorities across the Koshi basin. The model has a good potential for application in similar river basins in the Himalayan region.

  14. Self-induced vomiting and dental erosion--a clinical study.

    Science.gov (United States)

    Uhlen, Marte-Mari; Tveit, Anne Bjørg; Stenhagen, Kjersti Refsholt; Mulic, Aida

    2014-07-29

    In individuals suffering from eating disorders (ED) characterized by vomiting (e.g. bulimia nervosa), the gastric juice regularly reaches the oral cavity, causing a possible risk of dental erosion. This study aimed to assess the occurrence, distribution and severity of dental erosions in a group of Norwegian patients experiencing self-induced vomiting (SIV). The individuals included in the study were all undergoing treatment at clinics for eating disorders and were referred to a university dental clinic for examinations. One calibrated clinician registered erosions using the Visual Erosion Dental Examination (VEDE) system. Of 72 referred patients, 66 (63 females and three males, mean age 27.7 years) were or had been experiencing SIV (mean duration 10.6 years; range: 3 - 32 years), and were therefore included in the study. Dental erosions were found in 46 individuals (69.7%), 19 had enamel lesions only, while 27 had both enamel and dentine lesions. Ten or more teeth were affected in 26.1% of those with erosions, and 9% had ≥10 teeth with dentine lesions. Of the erosions, 41.6% were found on palatal/lingual surfaces, 36.6% on occlusal surfaces and 21.8% on buccal surfaces. Dentine lesions were most often found on lower first molars, while upper central incisors showed enamel lesions most frequently. The majority of the erosive lesions (48.6%) were found in those with the longest illness period, and 71.7% of the lesions extending into dentine were also found in this group. However, despite suffering from SIV for up to 32 years, 30.3% of the individuals showed no lesions. Dental erosion commonly affects individuals with ED experiencing SIV, and is more often found on the palatal/lingual surfaces than on the buccal in these individuals, confirming a common clinical assumption.

  15. Old age and male sex are associated with increased risk of asymptomatic erosive esophagitis: analysis of data from local health examinations by the Korean National Health Insurance Corporation.

    Science.gov (United States)

    Cho, Jae Hee; Kim, Hee Man; Ko, Geun Jun; Woo, Myoung Lyeol; Moon, Chang Mo; Kim, Yu Jin; Han, Ki Jun; Song, Si Young; Cho, Hyeon Geun

    2011-06-01

    Silent gastroesophageal reflux disease (GERD) is often detected during routine screening esophagogastroduodenoscopy (EGD). However, the risk factors and clinical implications of silent GERD remain unclear. In the present study, we investigated the risk factors for asymptomatic erosive esophagitis by analyzing the local area health examination data. The Korean National Health Insurance Corporation provides a bi-annual health examination performed by qualified local hospitals for the early detection of cancer in medical insurance holders over 40 years of age. Participants who completed self-reported questionnaires on health, followed by EGD at the Myongji Hospital (Goyang, Korea), were enrolled in this study. The data of a total of 5301 participants who underwent EGD between January 2005 and December 2008 were analyzed. The prevalence of erosive esophagitis was 6%. In the multivariate analysis, erosive esophagitis was strongly associated with an age greater than 60 years (odds ratio [OR]: 0.7, 95% confidence interval [CI]: 0.6-1.0), male sex (OR: 2.3, 95% CI: 1.7-3.0), hiatus hernia (OR: 2.9, 95% CI: 2.1-4.0), duodenal ulcer (OR: 1.6, 95% CI: 1.1-2.5), hypertension (OR: 1.5, 95% CI: 1.2-2.0), and smoking (OR: 1.4, 95% CI: 1.0-1.8). Of the 320 participants with erosive esophagitis, 145 (45.3%) were asymptomatic participants, and those who were more frequently greater than 60 years (OR: 1.8, 95% CI: 1.1-3.1) and male (OR: 1.8, 95% CI: 1.1-3.2). Asymptomatic erosive esophagitis in adults older than 40 years is strongly associated with old age (≥ 60 years) and male sex compared with symptomatic erosive esophagitis. © 2011 Journal of Gastroenterology and Hepatology Foundation and Blackwell Publishing Asia Pty Ltd.

  16. Advances in soil erosion modelling through remote sensing data availability at European scale

    Science.gov (United States)

    Panagos, Panos; Karydas, Christos; Borrelli, Pasqualle; Ballabio, Cristiano; Meusburger, Katrin

    2014-08-01

    Under the European Union's Thematic Strategy for Soil Protection, the European Commission's Directorate-General for the Environment (DG Environment) has identified the mitigation of soil losses by erosion as a priority area. Policy makers call for an overall assessment of soil erosion in their geographical area of interest. They have asked that risk areas for soil erosion be mapped under present land use and climate conditions, and that appropriate measures be taken to control erosion within the legal and social context of natural resource management. Remote sensing data help to better assessment of factors that control erosion, such as vegetation coverage, slope length and slope angle. In this context, the data availability of remote sensing data during the past decade facilitates the more precise estimation of soil erosion risk. Following the principles of the Universal Soil Loss Equation (USLE), various options to calculate vegetative cover management (C-factor) have been investigated. The use of the CORINE Land Cover dataset in combination with lookup table values taken from the literature is presented as an option that has the advantage of a coherent input dataset but with the drawback of static input. Recent developments in the Copernicus programme have made detailed datasets available on land cover, leaf area index and base soil characteristics. These dynamic datasets allow for seasonal estimates of vegetation coverage, and their application in the G2 soil erosion model which represents a recent approach to the seasonal monitoring of soil erosion. The use of phenological datasets and the LUCAS land use/cover survey are proposed as auxiliary information in the selection of the best methodology.

  17. Influence of Intrinsic Factors on Erosive Tooth Wear in a Large-Scale Epidemiological Study.

    Science.gov (United States)

    Alaraudanjoki, Viivi; Laitala, Marja-Liisa; Tjäderhane, Leo; Pesonen, Paula; Lussi, Adrian; Ronkainen, Jukka; Anttonen, Vuokko

    2016-01-01

    To assess the influence of self-reported intrinsic factors [gastroesophageal reflux disease (GERD), long-term alcoholism, long-term heavy use of alcohol and multiple pregnancies] on erosive tooth wear in a middle-aged cohort sample. Of the total Northern Finland Birth Cohort (NFBC 1966), a convenience sample (n = 3,181) was invited for an oral health examination in 2012-2013, of which 1,962 participated, comprising the final study group. Erosive tooth wear was assessed by sextants using the Basic Erosive Wear Examination Index (BEWE, 0-18). Clinical data were supplemented by questionnaires conducted in 1997/1998 and 2012/2013. The participants were divided into severe (BEWE sum ≥9) and no-to-moderate (BEWE sum 0-8) erosive wear groups, and the logistic regression model was applied. Selected intrinsic factors were quite rare in this cohort sample and explained only 5.9% of the difference in the prevalence and severity of erosive wear. Daily symptoms of GERD [odds ratio (OR) 3.8, confidence interval (CI) 1.2-12.0] and hyposalivation (OR 3.8, CI 1.2-11.8) were the strongest risk indicators for severe erosive wear. Additionally, variables associated with an elevated risk for severe erosive wear were diagnosed alcoholism at any point (OR 2.5, CI 0.7-9.7) and self-reported heavy use of alcohol in both questionnaires (OR 2.0, CI 0.6-6.2). Even low-dose long-term consumption of alcohol was associated with erosive wear. In this cohort sample, intrinsic factors such as GERD or alcoholism alone are relatively uncommon causes of erosive tooth wear. The role of long-term use of alcohol in the erosion process may be bigger than presumed. © 2016 S. Karger AG, Basel.

  18. Impacts of the post-fire erosion processes compared with the agricultural erosion rates for a mountain catchment in NW Iberia

    Science.gov (United States)

    Marisa Santos, Juliana; Nunes, João Pedro; Bernard-Jannin, Léonard; Gonzalez Pelayo, Oscar; Keizer, Jan Jacob

    2014-05-01

    Mediterranean ecosystems are very vulnerable to soil erosion by water due to particular characteristics of climate, lithology and land use history. Moreover, the foreseen climate changes might worsen land degradation and desertification, in which soil erosion has been classified as one of the most important driving forces. In this context, the frequent forest fires seen in some Mediterranean regions can case disturbances to vegetation cover and enhance soil erosion processes. This work addresses this issue for the Caramulo mountain range, NW Iberia. In the past century, large land use changes occurred due to massive afforestation. Changes from mixed natural forest cover and shrublands to Pine, the introduction of Eucalyptus plantations and, more recently, a trend for the substitution of pines by eucalypts, are the evidence of a large and rapid land use change in the last decades. Forest fires started to occur as afforestation proceeded, as a consequence of the disappearance of pasturage and accumulation of highly inflammable material; they became more frequent after the 1960's and became a determinant factor for land use changes in this region. Data collection focused on the Macieira de Alcoba catchment, a headwater agro-forested catchment (94 ha) located in this region. It has a wet Mediterranean climate, with an average annual rainfall of about 1300 mm (2002-2012), concentrated in autumn and winter, while spring and summer are dryer seasons. The mean annual temperature is 14°C and in summer it can reach 35°C. The land use is mixed, with forest and agriculture lands covering respectively 60 and 35% of the catchment area, 5% being built-up areas in the village of Macieira de Alcoba. In the last decades, this catchment suffered several forest fires (in 1969, 1986, 1991, and 2011). Erosion processes are related with periods of low vegetation cover in autumn in fields with a pasture-corn rotation, but also with forest plantations after clear-cutting and especially

  19. Genetic risk score predicting risk of rheumatoid arthritis phenotypes and age of symptom onset.

    Directory of Open Access Journals (Sweden)

    Lori B Chibnik

    Full Text Available Cumulative genetic profiles can help identify individuals at high-risk for developing RA. We examined the impact of 39 validated genetic risk alleles on the risk of RA phenotypes characterized by serologic and erosive status.We evaluated single nucleotide polymorphisms at 31 validated RA risk loci and 8 Human Leukocyte Antigen alleles among 542 Caucasian RA cases and 551 Caucasian controls from Nurses' Health Study and Nurses' Health Study II. We created a weighted genetic risk score (GRS and evaluated it as 7 ordinal groups using logistic regression (adjusting for age and smoking to assess the relationship between GRS group and odds of developing seronegative (RF- and CCP-, seropositive (RF+ or CCP+, erosive, and seropositive, erosive RA phenotypes. In separate case only analyses, we assessed the relationships between GRS and age of symptom onset. In 542 RA cases, 317 (58% were seropositive, 163 (30% had erosions and 105 (19% were seropositive with erosions. Comparing the highest GRS risk group to the median group, we found an OR of 1.2 (95% CI = 0.8-2.1 for seronegative RA, 3.0 (95% CI = 1.9-4.7 for seropositive RA, 3.2 (95% CI = 1.8-5.6 for erosive RA, and 7.6 (95% CI = 3.6-16.3 for seropositive, erosive RA. No significant relationship was seen between GRS and age of onset.Results suggest that seronegative and seropositive/erosive RA have different genetic architecture and support the importance of considering RA phenotypes in RA genetic studies.

  20. Relationship between food habits and tooth erosion occurrence in Malaysian University students.

    Science.gov (United States)

    Manaf, Zahara Abdul; Lee, Mei Tee; Ali, Nor Hazirah Muhammad; Samynathan, Selvamary; Jie, Ying Phor; Ismail, Noor Hasnani; Bibiana Hui Ying, Yong; Wei Seng, Yeo; Yahya, Nurul Asyikin

    2012-04-01

    Tooth erosion is a growing dental problem; however, the role of diet in the aetiology of tooth erosion is unclear. A cross-sectional study was conducted to determine the association between tooth erosion occurrence and the consumption of acidic foods and drinks among undergraduate university students. A total of 150 undergraduate students (33 males and 117 females) aged 19 to 24 years at Universiti Kebangsaan Malaysia participated in this study. The Basic Erosive Wear Examination was used to assess the occurrence of tooth erosion. Information regarding dental hygiene practices, usual dietary habits, and consumption of acidic foods and drinks was obtained through a structured questionnaire. In all, 68% of subjects had tooth erosion. Subjects who reported having received information about healthy eating were less likely to have tooth erosion (χ(2) [1, N = 150] = 7.328, P = 0.007). The frequencies of milk (OR = 0.29, 95% CI = 0.13-0.67) and tea/coffee (adjusted OR = 0.42, 95% CI = 0.19-0.95) consumption were negatively associated with tooth erosion. Dental hygiene practice, the frequency and amount of acidic food and drink intake, and body mass index classification were not significantly associated with the risk of tooth erosion (P > 0.05). A high prevalence of tooth erosion was observed among this group of students. Preventive measures, such as dietary advice and increased consumption of milk at a younger age, may reduce the occurrence of tooth erosion among this age group.

  1. Monitoring and assessment of soil erosion at micro-scale and macro-scale in forests affected by fire damage in northern Iran.

    Science.gov (United States)

    Akbarzadeh, Ali; Ghorbani-Dashtaki, Shoja; Naderi-Khorasgani, Mehdi; Kerry, Ruth; Taghizadeh-Mehrjardi, Ruhollah

    2016-12-01

    Understanding the occurrence of erosion processes at large scales is very difficult without studying them at small scales. In this study, soil erosion parameters were investigated at micro-scale and macro-scale in forests in northern Iran. Surface erosion and some vegetation attributes were measured at the watershed scale in 30 parcels of land which were separated into 15 fire-affected (burned) forests and 15 original (unburned) forests adjacent to the burned sites. The soil erodibility factor and splash erosion were also determined at the micro-plot scale within each burned and unburned site. Furthermore, soil sampling and infiltration studies were carried out at 80 other sites, as well as the 30 burned and unburned sites, (a total of 110 points) to create a map of the soil erodibility factor at the regional scale. Maps of topography, rainfall, and cover-management were also determined for the study area. The maps of erosion risk and erosion risk potential were finally prepared for the study area using the Revised Universal Soil Loss Equation (RUSLE) procedure. Results indicated that destruction of the protective cover of forested areas by fire had significant effects on splash erosion and the soil erodibility factor at the micro-plot scale and also on surface erosion, erosion risk, and erosion risk potential at the watershed scale. Moreover, the results showed that correlation coefficients between different variables at the micro-plot and watershed scales were positive and significant. Finally, assessment and monitoring of the erosion maps at the regional scale showed that the central and western parts of the study area were more susceptible to erosion compared with the western regions due to more intense crop-management, greater soil erodibility, and more rainfall. The relationships between erosion parameters and the most important vegetation attributes were also used to provide models with equations that were specific to the study region. The results of this

  2. The Arctic Coastal Erosion Problem

    Energy Technology Data Exchange (ETDEWEB)

    Frederick, Jennifer M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Thomas, Matthew Anthony [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bull, Diana L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jones, Craig A. [Integral Consulting Inc., San Francisco, CA (United States); Roberts, Jesse D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-09-01

    Permafrost-dominated coastlines in the Arctic are rapidly disappearing. Arctic coastal erosion rates in the United States have doubled since the middle of the twentieth century and appear to be accelerating. Positive erosion trends have been observed for highly-variable geomorphic conditions across the entire Arctic, suggesting a major (human-timescale) shift in coastal landscape evolution. Unfortunately, irreversible coastal land loss in this region poses a threat to native, industrial, scientific, and military communities. The Arctic coastline is vast, spanning more than 100,000 km across eight nations, ten percent of which is overseen by the United States. Much of area is inaccessible by all-season roads. People and infrastructure, therefore, are commonly located near the coast. The impact of the Arctic coastal erosion problem is widespread. Homes are being lost. Residents are being dispersed and their villages relocated. Shoreline fuel storage and delivery systems are at greater risk. The U.S. Department of Energy (DOE) and Sandia National Laboratories (SNL) operate research facilities along some of the most rapidly eroding sections of coast in the world. The U.S. Department of Defense (DOD) is struggling to fortify coastal radar sites, operated to ensure national sovereignty in the air, against the erosion problem. Rapid alterations to the Arctic coastline are facilitated by oceanographic and geomorphic perturbations associated with climate change. Sea ice extent is declining, sea level is rising, sea water temperature is increasing, and permafrost state is changing. The polar orientation of the Arctic exacerbates the magnitude and rate of the environmental forcings that facilitate coastal land area loss. The fundamental mechanics of these processes are understood; their non-linear combination poses an extreme hazard. Tools to accurately predict Arctic coastal erosion do not exist. To obtain an accurate predictive model, a coupling of the influences of

  3. Glaucoma Drainage Device Erosion Following Ptosis Surgery.

    Science.gov (United States)

    Bae, Steven S; Campbell, Robert J

    2017-09-01

    To highlight the potential risk of glaucoma drainage device erosion following ptosis surgery. Case report. A 71-year-old man underwent uncomplicated superotemporal Ahmed glaucoma valve implantation in the left eye in 2008. Approximately 8 years later, the patient underwent bilateral ptosis repair, which successfully raised the upper eyelid position. Three months postoperatively, the patient's glaucoma drainage implant tube eroded through the corneal graft tissue and overlying conjunctiva to become exposed. A graft revision surgery was successfully performed with no further complications. Caution and conservative lid elevation may be warranted when performing ptosis repair in patients with a glaucoma drainage implant, and patients with a glaucoma implant undergoing ptosis surgery should be followed closely for signs of tube erosion.

  4. Mesh erosion after abdominal sacrocolpopexy.

    Science.gov (United States)

    Kohli, N; Walsh, P M; Roat, T W; Karram, M M

    1998-12-01

    To report our experience with erosion of permanent suture or mesh material after abdominal sacrocolpopexy. A retrospective chart review was performed to identify patients who underwent sacrocolpopexy by the same surgeon over 8 years. Demographic data, operative notes, hospital records, and office charts were reviewed after sacrocolpopexy. Patients with erosion of either suture or mesh were treated initially with conservative therapy followed by surgical intervention as required. Fifty-seven patients underwent sacrocolpopexy using synthetic mesh during the study period. The mean (range) postoperative follow-up was 19.9 (1.3-50) months. Seven patients (12%) had erosions after abdominal sacrocolpopexy with two suture erosions and five mesh erosions. Patients with suture erosion were asymptomatic compared with patients with mesh erosion, who presented with vaginal bleeding or discharge. The mean (+/-standard deviation) time to erosion was 14.0+/-7.7 (range 4-24) months. Both patients with suture erosion were treated conservatively with estrogen cream. All five patients with mesh erosion required transvaginal removal of the mesh. Mesh erosion can follow abdominal sacrocolpopexy over a long time, and usually presents as vaginal bleeding or discharge. Although patients with suture erosion can be managed successfully with conservative treatment, patients with mesh erosion require surgical intervention. Transvaginal removal of the mesh with vaginal advancement appears to be an effective treatment in patients failing conservative management.

  5. Quantifying thresholds for significant dune erosion along the Sefton Coast, Northwest England

    Science.gov (United States)

    Esteves, Luciana S.; Brown, Jennifer M.; Williams, Jon J.; Lymbery, Graham

    2012-03-01

    Field and model hindcast data are used to establish a critical dune erosion threshold for the Sefton Coast (NW England). Events are classified as causing significant erosion if they result in: (a) a mean dune retreat along the entire study area of > 2 m; (b) a dune retreat of ≥ 5 m along a coastal segment ≥ 2 km in length; and (c) an eroded area ≥ 20,000 m2. For the period 1996 to 2008, individual storms were characterised using hindcast results from a POLCOMS-WAM model and measured data from the Liverpool Bay Coastal Observatory. Results show that combined extreme surge levels (> 1.5 m) and wave heights (> 4 m), or tidal water levels above 9.0 m Chart Datum (CD), do not always result in significant dune erosion. Evidence suggests that erosion is more likely to occur when wave heights are > 2.6 m, peak water level is > 10.2 m CD at Liverpool and when consecutive tidal cycles provide 10 h or more of water levels above 9.4 m CD. However, lower water levels and wave heights, and shorter events of sustained water levels, can cause significant erosion in the summer. While the return period for events giving rise to the most severe erosion in the winter is > 50 years, significant erosion in the summer can be caused by events with return periods dune toe elevation c. 30 cm. Although the study shows it might be possible to characterise objectively storm events based on oceanographic conditions, the resultant morphological change at the coast is demonstrated to depend on the time and duration of events, and on other variables which are not so easy to quantify. Further investigation is needed to understand the influence of alongshore and seasonal variability in beach/dune morphology in determining the response to the hydrodynamic and meteorological conditions causing significant erosion. Improved monitoring pre- and post-storm of changes in beach/dune morphology is required to develop reliable proxies that can be used to establish early warning systems to mitigate the

  6. Susceptibility of bovine dental enamel with initial erosion lesion to new erosive challenges.

    Science.gov (United States)

    Oliveira, Gabriela Cristina de; Tereza, Guida Paola Genovez; Boteon, Ana Paula; Ferrairo, Brunna Mota; Gonçalves, Priscilla Santana Pinto; Silva, Thiago Cruvinel da; Honório, Heitor Marques; Rios, Daniela

    2017-01-01

    This in vitro study evaluated the impact of initial erosion on the susceptibility of enamel to further erosive challenge. Thirty bovine enamel blocks were selected by surface hardness and randomized into two groups (n = 15): GC- group composed by enamel blocks without erosion lesion and GT- group composed by enamel blocks with initial erosion lesion. The baseline profile of each block was determined using the profilometer. The initial erosion was produced by immersing the blocks into HCl 0.01 M, pH 2.3 for 30 seconds, under stirring. The erosive cycling consisted of blocks immersion in hydrochloric acid (0.01 M, pH 2.3) for 2 minutes, followed by immersion in artificial saliva for 120 minutes. This procedure was repeated 4 times a day for 5 days, and the blocks were kept in artificial saliva overnight. After erosive cycling, final profile measurement was performed. Profilometry measured the enamel loss by the superposition of initial and final profiles. Data were analyzed by t-test (perosion on bovine dental enamel does not enhance its susceptibility to new erosive challenges.

  7. Susceptibility of bovine dental enamel with initial erosion lesion to new erosive challenges.

    Directory of Open Access Journals (Sweden)

    Gabriela Cristina de Oliveira

    Full Text Available This in vitro study evaluated the impact of initial erosion on the susceptibility of enamel to further erosive challenge. Thirty bovine enamel blocks were selected by surface hardness and randomized into two groups (n = 15: GC- group composed by enamel blocks without erosion lesion and GT- group composed by enamel blocks with initial erosion lesion. The baseline profile of each block was determined using the profilometer. The initial erosion was produced by immersing the blocks into HCl 0.01 M, pH 2.3 for 30 seconds, under stirring. The erosive cycling consisted of blocks immersion in hydrochloric acid (0.01 M, pH 2.3 for 2 minutes, followed by immersion in artificial saliva for 120 minutes. This procedure was repeated 4 times a day for 5 days, and the blocks were kept in artificial saliva overnight. After erosive cycling, final profile measurement was performed. Profilometry measured the enamel loss by the superposition of initial and final profiles. Data were analyzed by t-test (p<0.05. The result showed no statistically significant difference between groups (GS = 14.60±2.86 and GE = .14.69±2.21 μm. The presence of initial erosion on bovine dental enamel does not enhance its susceptibility to new erosive challenges.

  8. Classifying risk status of non-clinical adolescents using psychometric indicators for psychosis spectrum disorders.

    Science.gov (United States)

    Fonseca-Pedrero, Eduardo; Gooding, Diane C; Ortuño-Sierra, Javier; Pflum, Madeline; Paino, Mercedes; Muñiz, José

    2016-09-30

    This study is an attempt to evaluate extant psychometric indicators using latent profile analysis for classifying community-derived individuals based on a set of clinical, behavioural, and personality traits considered risk markers for psychosis spectrum disorders. The present investigation included four hundred and forty-nine high-school students between the ages of 12 and 19. We used the following to assess risk: the Prodromal Questionnaire-Brief (PQ-B), Oviedo Schizotypy Assessment Questionnaire (ESQUIZO-Q), Anticipatory and Consummatory Interpersonal Pleasure Scale-Adolescent version (ACIPS-A), and General Health Questionnaire 12 (GHQ-12). Using Latent profile analysis six latent classes (LC) were identified: participants in class 1 (LC1) displayed little or no symptoms and accounted for 38.53% of the sample; class 2 (LC2), who accounted for 28.06%, also produced low mean scores across most measures though they expressed somewhat higher levels of subjective distress; LC3, a positive schizotypy group (10.24%); LC4 (13.36%), a psychosis high-risk group; LC5, a high positive and negative schizotypy group (4.45%); and LC6, a very high distress, severe clinical high-risk group, comprised 5.34% of the sample. The current research indicates that different latent classes of early individuals at risk can be empirically defined in adolescent community samples using psychometric indicators for psychosis spectrum disorders. These findings may have implications for early detection and prevention strategies in psychosis spectrum disorders. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  9. Protection from erosion following wildfire

    Science.gov (United States)

    Peter R. Robichaud; William J. Elliot

    2006-01-01

    Erosion in the first year after a wildfire can be up to three orders of magnitude greater than the erosion from undisturbed forests. To mitigate potential postfire erosion, various erosion control treatments are applied on highly erodible areas with downstream resources in need of protection. Because postfire erosion rates generally decline by an order of magnitude for...

  10. Erosion rills offset the efficacy of vegetated buffer strips to mitigate pesticide exposure in surface waters.

    Science.gov (United States)

    Stehle, Sebastian; Dabrowski, James Michael; Bangert, Uli; Schulz, Ralf

    2016-03-01

    Regulatory risk assessment considers vegetated buffer strips as effective risk mitigation measures for the reduction of runoff-related pesticide exposure of surface waters. However, apart from buffer strip widths, further characteristics such as vegetation density or the presence of erosion rills are generally neglected in the determination of buffer strip mitigation efficacies. This study conducted a field survey of fruit orchards (average slope 3.1-12.2%) of the Lourens River catchment, South Africa, which specifically focused on the characteristics and attributes of buffer strips separating orchard areas from tributary streams. In addition, in-stream and erosion rill water samples were collected during three runoff events and GIS-based modeling was employed to predict losses of pesticides associated with runoff. The results show that erosion rills are common in buffer strips (on average 13 to 24 m wide) of the tributaries (up to 6.5 erosion rills per km flow length) and that erosion rills represent concentrated entry pathways of pesticide runoff into the tributaries during rainfall events. Exposure modeling shows that measured pesticide surface water concentrations correlated significantly (R(2)=0.626; pregulatory risk assessment procedures conducted for pesticide authorization. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Impacts of Climate Change on Soil Erosion in the Great Lakes Region

    Directory of Open Access Journals (Sweden)

    Lili Wang

    2018-06-01

    Full Text Available Quantifying changes in potential soil erosion under projections of changing climate is important for the sustainable management of land resources, as soil loss estimates will be helpful in identifying areas susceptible to erosion, targeting future erosion control efforts, and/or conservation funding. Therefore, the macro-scale Variable Infiltration Capacity—Water Erosion Prediction Project (VIC-WEPP soil erosion model was utilized to quantify soil losses under three climate change scenarios (A2, A1B, B1 using projections from three general circulation models (GFDL, PCM, HadCM3 for the Great Lakes region from 2000 to 2100. Soil loss was predicted to decrease throughout three future periods (2030s, 2060s, and 2090s by 0.4–0.7 ton ha−1 year−1 (4.99–23.2% relative to the historical period (2000s with predicted air temperature increases of 0.68–4.34 °C and precipitation increases of 1.74–63.7 mm year−1 (0.23–8.6%. In the forested northern study domain erosion kept increasing by 0.01–0.18 ton ha−1 year−1 over three future periods due to increased precipitation of 9.7–68.3 mm year−1. The southern study domain covered by cropland and grassland had predicted soil loss decreases of 0.01–1.43 ton ha−1 year−1 due to air temperature increases of 1.75–4.79 °C and reduced precipitation in the summer. Fall and winter had greater risks of increased soil loss based on predictions for these two seasons under the A2 scenario, with the greatest cropland soil loss increase due to increased fall precipitation, and combined effects of increases in both precipitation and air temperature in the winter. Fall was identified with higher risks under the A1B scenario, while spring and summer were identified with the greatest risk of increased soil losses under the B1 scenario due to the increases in both precipitation and air temperature.

  12. Soil losses from typic cambisols and red latosol as related to three erosive rainfall patterns

    Directory of Open Access Journals (Sweden)

    Regimeire Freitas Aquino

    2013-02-01

    Full Text Available Rainfall erosivity is one of the main factors related to water erosion in the tropics. This work focused on relating soil loss from a typic dystrophic Tb Haplic Cambisol (CXbd and a typic dystrophic Red Latosol (LVdf to different patterns of natural erosive rainfall. The experimental plots of approximately 26 m² (3 x 8.67 m consisted of a CXbd area with a 0.15 m m-1 slope and a LVdf area with 0.12 m m-1 slope, both delimited by galvanized plates. Drainpipes were installed at the lower part of these plots to collect runoff, interconnected with a Geib or multislot divisor. To calculate erosivity (EI30, rainfall data, recorded continuously at a weather station in Lavras, were used. The data of erosive rainfall events were measured (10 mm precipitation intervals, accuracy 0.2 mm, 24 h period, 20 min intervals, characterized as rainfall events with more than 10 mm precipitation, maximum intensity > 24 mm h-1 within 15 min, or kinetic energy > 3.6 MJ, which were used in this study to calculate the rainfall erosivity parameter, were classified according to the moment of peak precipitation intensity in advanced, intermediate and delayed patterns. Among the 139 erosive rainfall events with CXbd soil loss, 60 % were attributed to the advanced pattern, with a loss of 415.9 Mg ha-1, and total losses of 776.0 Mg ha-1. As for the LVdf, of the 93 erosive rainfall events with soil loss, 58 % were listed in the advanced pattern, with 37.8 Mg ha-1 soil loss and 50.9 Mg ha-1 of total soil loss. The greatest soil losses were observed in the advanced rain pattern, especially for the CXbd. From the Cambisol, the soil loss per rainfall event was greatest for the advanced pattern, being influenced by the low soil permeability.

  13. Dental erosion among 12-14 year old school children in Khartoum: a pilot study.

    Science.gov (United States)

    El Karim, I A; Sanhouri, N M; Hashim, N T; Ziada, H M

    2007-09-01

    To investigate dental erosion among 12-14 year old Sudanese school children and evaluate the associated risk factors. Cross sectional survey in secondary schools in Khartoum city, Sudan. A sample of 157 school children was obtained from both private and public schools. Erosion on the labial and palatal surfaces of maxillary incisors was measured by criterion based on the Smith and Knight Tooth Wear Index. Dietary intake and other related factors were assessed using a questionnaire. The overall erosion prevalence in this group was 66.9%, of which 45.2% was mild and 21.7% was moderate erosion. A strong association was found between erosion and private schooling (higher socioeconomic groups), carbonated drinks, herbal hibiscus drink and traditional acidic food consumption. There was a high prevalence of dental erosion among Sudanese school children which was mild to moderate in severity and was strongly associated with acidic dietary intake

  14. Seasonal variation and climate change impact in Rainfall Erosivity across Europe

    Science.gov (United States)

    Panagos, Panos; Borrelli, Pasquale; Meusburger, Katrin; Alewell, Christine; Ballabio, Cristiano

    2017-04-01

    Rainfall erosivity quantifies the climatic effect on water erosion and is of high importance for soil scientists, land use planners, agronomists, hydrologists and environmental scientists in general. The rainfall erosivity combines the influence of rainfall duration, magnitude, frequency and intensity. Rainfall erosivity is calculated from a series of single storm events by multiplying the total storm kinetic energy with the measured maximum 30-minute rainfall intensity. This estimation requests high temporal resolution (e.g. 30 minutes) rainfall data for sufficiently long time periods (i.e. 20 years). The European Commission's Joint Research Centr(JRC) in collaboration with national/regional meteorological services and Environmental Institutions made an extensive data collection of high resolution rainfall data in the 28 Member States of the European Union plus Switzerland to estimate rainfall erosivity in Europe. This resulted in the Rainfall Erosivity Database on the European Scale (REDES) which included 1,675 stations. The interpolation of those point erosivity values with a Gaussian Process Regression (GPR) model has resulted in the first Rainfall Erosivity map of Europe (Science of the Total Environment, 511: 801-815). In 2016, REDES extended with a monthly component, which allowed developing monthly and seasonal erosivity maps and assessing rainfall erosivity both spatially and temporally for European Union and Switzerland. The monthly erosivity maps have been used to develop composite indicators that map both intra-annual variability and concentration of erosive events (Science of the Total Environment, 579: 1298-1315). Consequently, spatio-temporal mapping of rainfall erosivity permits to identify the months and the areas with highest risk of soil loss where conservation measures should be applied in different seasons of the year. Finally, the identification of the most erosive month allows recommending certain agricultural management practices (crop

  15. Mapping erosion from space

    NARCIS (Netherlands)

    Vrieling, A.

    2007-01-01

    Soil erosion by water is the most important land degradation problem worldwide. Spatial information on erosion is required for defining effective soil and water conservation strategies. Satellite remote sensing can provide relevant input to regional erosion assessment. This thesis comprises a review

  16. Erosion problems in Alexandroupolis coastline, North-Eastern Greece

    Science.gov (United States)

    Xeidakis, G. S.; Delimani, P.; Skias, S.

    2007-12-01

    This paper deals with the coastal erosion processes and the related problems around the city of Alexandroupolis, NE Aegean Sea, N. Greece. The area is very fast developing, as the city is an important port and a summer resort center in SE Balkans, and will become soon a transportation and energy center, as well. The coastline under study exhibits an east west orientation and has a length of more than 50 km. The spatial distribution and the characteristics of the changes in the shoreline were studied by comparing old and new air photographs and topographic maps, as well as through repeated series of field observations and local measurements regarding the erosion process. From these studies it was concluded that the greater stretch of the western part of the coast, under consideration, is of moderate to high relief, with a considerable participation of coastal cliffs. It consists of conglomerates of varying granulometry and consistency and is under moderate to severe erosion process. The erosion phenomena in the western part of the coast may be attributed, primarily, to strong S, SW winds, blowing in the area and to trapping of sediments by Alexandroupolis’ port breakwaters; the port stops or/and diverts the sediments to the open sea; and to the east to west longshore sea current, prevailing in the area. The eastern stretch of the coast is a plain area, formed by sandy silty sediments; being a part of the river Evros’ Delta, it is under deposition and accretes seawards. The majority of the coasts under consideration are classified as coasts of high wave energy potential. Hard structures, as shore protection measures, have been constructed in some places, but they were proved, in rather short time-period, ineffective and suffered extensive failures. Thus, it is argued that for a long-term cost-effective tackling of the various erosion problems on any stretch, priority must be given to soft engineering measures; although, certain hard measures, carefully selected

  17. Developing an Erosion Rate Map for Myanmar Using USLE, GIS and Remote Sensing

    Science.gov (United States)

    Emtehani, Sobhan; Rutten, Martine

    2017-04-01

    Predicting erosion and estimating sediment loads in rivers are of major tasks in water resources system planning and management. In Myanmar erosion and collapse of river banks is common during the rainy season and riverine communities are frequently forced to relocate as their homes are dangerously close to the disintegrating river banks (Mann 2013). Myanmar is one of climatically most diverse countries located in Southeast Asia, where sheet, rill, and gully erosion affect crop yields as well as livelihood strategies of many people (Htwe, Brinkmann et al. 2015). In Myanmar, soil erosion measurement and monitoring approaches are increasingly important for land management planning to effectively avoid erosion and soil degradation, but such monitoring is limited by the availability of data and budgetary constraints. Therefore, spatial modeling approaches using GIS and remote sensing techniques play an important role for rapid risk assessments (Htwe 2016). In this study ''Model Builder'' tool in ArcGIS was used to create a model which generates an erosion rate map using Universal Soil Loss Equation (USLE). USLE is the product of five factors: rainfall erosivity factor (R), soil erodibility factor (K), slope length and steepness factor (LS), crop management factor (C), and support practice factor (P). Input data files for this model were acquired from online open source databases. Precipitation data was downloaded from Tropical Rainfall Measuring Mission (TRMM) for calculation of R factor. The resolution of TRMM data is very coarse (0.25 degree × 0.25 degree), therefore it was spatially downscaled by developing a relation between TRMM and Normalized Difference Vegetation Index (NDVI) using regression analysis method. Soil maps depicting percentages of sand, clay and silt were obtained from soilgrids website for calculation of K factor. Digital Elevation Model (DEM) with resolution of 90 meters was taken from Shuttle Radar Topography Mission (SRTM) for calculation of LS

  18. Best management practices to reduce and prevent water pollution with herbicides from run-off and erosion

    Directory of Open Access Journals (Sweden)

    Gehring, Klaus

    2014-02-01

    Full Text Available The natural phenomenon of run-off and erosion lead to unpreventable pesticide water pollution in case of extreme weather conditions. In this relationship the use of herbicides involves a higher risk than other pesticides because of the specific terms of application. Directive 2009/128/EC for the sustainable use of pesticides aspires to enhanced water protection. German national action plan contains quantitative objectives which require strong reduction of water pollution by run-off and erosion of pesticides and accordingly herbicides. The European TOPPS prowadis project developed a consolidated and basic diagnosis concept for the first time to determine the field specific run-off risk. Compatible mitigation measures were linked to specific risk scenarios. Risk diagnosis and suitable mitigation measures determine best management practices for the prevention of run-off and erosion. Different new diagnosis methods and the implementation are presented. Further documents and information are available on the web [http://www.topps-life.org/].

  19. Assessing the multidimensionality of coastal erosion risks: public participation and multicriteria analysis in a Mediterranean coastal system.

    Science.gov (United States)

    Roca, Elisabet; Gamboa, Gonzalo; Tàbara, J David

    2008-04-01

    The complex and multidimensional nature of coastal erosion risks makes it necessary to move away from single-perspective assessment and management methods that have conventionally predominated in coastal management. This article explores the suitability of participatory multicriteria analysis (MCA) for improving the integration of diverse expertises and values and enhancing the social-ecological robustness of the processes that lead to the definition of relevant policy options to deal with those risks. We test this approach in the Mediterranean coastal locality of Lido de Sète in France. Results show that the more adaptive alternatives such as "retreating the shoreline" were preferred by our selected stakeholders to those corresponding to "protecting the shoreline" and the business as usual proposals traditionally put forward by experts and policymakers on these matters. Participative MCA contributed to represent coastal multidimensionality, elicit and integrate different views and preferences, facilitated knowledge exchange, and allowed highlighting existing uncertainties.

  20. Following of erosive wash of soil in variants with different intercrops

    Directory of Open Access Journals (Sweden)

    Barbora Badalíková

    2010-01-01

    Full Text Available In a pilot experiment established in a sugar beet growing region the erosive washing away of soil was studied in the years 2006 to 2008. The area is located at an altitude of 246 m with the long-term mean precipitation of 500 mm and the mean annual temperature of 8.4 °C. The soils are classified as Chernozem, moderately heavy, loamy, with a good supply of nutrients, humus content of 2.30 % and an alkaline soil reaction. Slope gradient is 12 %, exposition is NE. To study the role of intercrops in erosion control, three variants were established after the harvest of the main crop, two variants with different intercrops and one (control with no intercrop. These were Variant 1 with Secale cereale L. var. multicaule METZG. ex ALEF., a non-freezing intercrop, Variant 2 with cluster mallow (Malva verticillata L., a freezing intercrop, and a control variant with no intercrop. In Variant 1 Secale cereale L. var. multicaule was desiccated with the herbicide Roundup in early spring. All the variants involved maize as the main crop. In variants 1 and 2, maize was sown in intercrop residues after seedbed preparation by Vario and a compactor. In Variant 3 maize was sown after conventional seedbed preparation. For assessment of soil conditions soil samples were taken to determine soil physical and chemical properties and water content in the soil. Soil loss by erosion was determined using specially-designed pockets. Erosive washing away of soil was monitored during the entire growing season of maize. The variants in which intercrops were used were found very effective in soil erosion control. In Variant 3 (control without surface crop residues, the washing away of soil was recorded with each heavy torrential rain. During the all years the total amount of soil loss by erosion in this treatment was 2.25 t . ha−1.

  1. Classifying PML risk with disease modifying therapies.

    Science.gov (United States)

    Berger, Joseph R

    2017-02-01

    To catalogue the risk of PML with the currently available disease modifying therapies (DMTs) for multiple sclerosis (MS). All DMTs perturb the immune system in some fashion. Natalizumab, a highly effective DMT, has been associated with a significant risk of PML. Fingolimod and dimethyl fumarate have also been unquestionably associated with a risk of PML in the MS population. Concerns about PML risk with other DMTs have arisen due to their mechanism of action and pharmacological parallel to other agents with known PML risk. A method of contextualizing PML risk for DMTs is warranted. Classification of PML risk was predicated on three criteria:: 1) whether the underlying condition being treated predisposes to PML in the absence of the drug; 2) the latency from initiation of the drug to the development of PML; and 3) the frequency with which PML is observed. Among the DMTs, natalizumab occupies a place of its own with respect to PML risk. Significantly lesser degrees of risk exist for fingolimod and dimethyl fumarate. Whether PML will be observed with other DMTs in use for MS, such as, rituximab, teriflunomide, and alemtuzumab, remains uncertain. A logical classification for stratifying DMT PML risk is important for both the physician and patient in contextualizing risk/benefit ratios. As additional experience accumulates regarding PML and the DMTs, this early effort will undoubtedly require revisiting. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Short-term transport of glyphosate with erosion in Chinese loess soil--a flume experiment.

    Science.gov (United States)

    Yang, Xiaomei; Wang, Fei; Bento, Célia P M; Xue, Sha; Gai, Lingtong; van Dam, Ruud; Mol, Hans; Ritsema, Coen J; Geissen, Violette

    2015-04-15

    Repeated applications of glyphosate may contaminate the soil and water and threaten their quality both within the environmental system and beyond it through water erosion related processes and leaching. In this study, we focused on the transport of glyphosate and its metabolite aminomethylphosphonic acid (AMPA) related to soil erosion at two slope gradients (10 and 20°), two rates of pesticide with a formulation of glyphosate (Roundup®) application (360 and 720 mg m(-2)), and a rain intensity of 1.0 mm min(-1) for 1 h on bare soil in hydraulic flumes. Runoff and erosion rate were significantly different within slope gradients (psoil at the end of the experiment decreased significantly with depth (psoil layers, respectively. The risk of contamination in deep soil and the groundwater was thus low, but 5% of the initial application did reach the 2-10 cm soil layer. The risk of contamination of surface water through runoff and sedimentation, however, can be considerable, especially in regions where rain-induced soil erosion is common. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Erosive gastritis

    International Nuclear Information System (INIS)

    Mohammed, S.H.; Conrad, C.; Kjoergaad, J.

    1982-01-01

    Erosive gastritis is a well-defined radiologic and endoscopic entity. It is one of the common causes of upper gastrointestinal bleeding, yet it is seldom diagnosed and often confused with a number of other diseases. This communication re-emphasizes the characteristic endoscopic and radiologic features of erosive gastritis and its differential diagnosis. Two representative cases are reported. (orig.)

  4. Erosive gastritis

    Energy Technology Data Exchange (ETDEWEB)

    Mohammed, S.H.; Conrad, C.; Kjoergaad, J.

    1982-08-01

    Erosive gastritis is a well-defined radiologic and endoscopic entity. It is one of the common causes of upper gastrointestinal bleeding, yet it is seldom diagnosed and often confused with a number of other diseases. This communication re-emphasizes the characteristic endoscopic and radiologic features of erosive gastritis and its differential diagnosis. Two representative cases are reported.

  5. Discovery and validation of a colorectal cancer classifier in a new blood test with improved performance for high-risk subjects

    DEFF Research Database (Denmark)

    Croner, Lisa J; Dillon, Roslyn; Kao, Athit

    2017-01-01

    BACKGROUND: The aim was to improve upon an existing blood-based colorectal cancer (CRC) test directed to high-risk symptomatic patients, by developing a new CRC classifier to be used with a new test embodiment. The new test uses a robust assay format-electrochemiluminescence immunoassays......, the indeterminate rate of the new panel was 23.2%, sensitivity/specificity was 0.80/0.83, PPV was 36.5%, and NPV was 97.1%. CONCLUSIONS: The validated classifier serves as the basis of a new blood-based CRC test for symptomatic patients. The improved performance, resulting from robust concentration measures across......-to quantify protein concentrations. The aim was achieved by building and validating a CRC classifier using concentration measures from a large sample set representing a true intent-to-test (ITT) symptomatic population. METHODS: 4435 patient samples were drawn from the Endoscopy II sample set. Samples were...

  6. Reduction in soil loss from erosion-susceptible soils amended with humic substances from oxidized coal

    International Nuclear Information System (INIS)

    Piccolo, A.; Pietramellara, G.; Mbagwu, J.S.C.

    1997-01-01

    Soils that pose high risk of erosion require amendment with either natural or synthetic soil conditioners to reduce soil loss hazards. The objective of this study was to evaluate the potential of using coal-derived humic substances (as soil conditioners) to reduce runoff erosion on erosion-susceptible soils. Surface samples of severely degraded soils from Principina in Tuscany and Bovolone in Venice in Italy were used to assess the effects of five rates (0, 0.05, 0.01, 0.50 and 1.00 g/kg) of humic acids (HA) on soil loss and other hydrological parameters. The results showed that amending erosion-susceptible soils with low rates of coal-derived humic substances is a potentially effective soil management practice for reducing erosion rates

  7. Assessing storm erosion hazards

    NARCIS (Netherlands)

    Ranasinghe, Ranasinghe W M R J B; Callaghan, D.; Ciavola, Paolo; Coco, Giovanni

    2017-01-01

    The storm erosion hazard on coasts is usually expressed as an erosion volume and/or associated episodic coastline retreat. The accurate assessment of present-day and future storm erosion volumes is a key task for coastal zone managers, planners and engineers. There are four main approaches that can

  8. Measurement of erosion: Is it possible?

    NARCIS (Netherlands)

    Stroosnijder, L.

    2005-01-01

    Reasons for erosion measurements are: (1) to determine the environmental impact of erosion and conservation practices, (2) scientific erosion research; (3) development and evaluation of erosion control technology; (4) development of erosion prediction technology and (5) allocation of conservation

  9. Gully erosion in the Caatinga biome, Brazil: measurement and stochastic modelling

    Science.gov (United States)

    Lima Alencar, Pedro Henrique; de Araújo, José Carlos; Nonato Távora Costa, Raimundo

    2017-04-01

    In contrast with inter-rill erosion, which takes a long time to modify the terrain form, gully erosion can fast and severely change the landscape. In the Brazilian semiarid region, a one-million km2 area that coincides with the Caatinga biome, inter-rill erosion prevails due to the silty shallow soils. However, gully erosion does occur in the Caatinga, with temporal increasing severity. This source of sediment impacts the existing dense network of small dams, generating significant deleterious effects, such as water availability reduction in a drought-prone region. This study focuses on the Madalena basin (124 km2, state of Ceará, Brazil), a land-reform settlement with 20 inhabitants per km2, whose main economic activities are agriculture (especially Zea mays), livestock and fishing. In the catchment area, where there are 12 dams (with storage capacity ranging from 6.104 to 2.107 m3), gully erosion has become an issue due to its increasing occurrence. Eight gully-erosion sites have been identified in the basin, but most of them have not yet reached great dimensions (depth and/or width), nor interacted with groundwater, being therefore classified as ephemeral gullies. We selected the three most relevant sites and measured the topography of the eroded channels, as well as the neighboring terrain relief, using accurate total stations and unmanned aerial vehicle. The data was processed with the help of software, such as DataGeosis (Office 7.5) and Surfer (11.0), providing information on gully erosion in terms of (μ ± σ): projection area (317±165 m2), eroded mass (61±36 Mg) and volume (42±25 m3), length (38±6 m), maximum depth (0.58±0.13 m) and maximum width (6.00±2.35 m). The measured data are then compared with those provided by the Foster and Lane model (1986). The model generated results with considerable scatter. This is possibly due to uncertainties in the field parameters, which are neglected in the deterministic approach of most physically-based models

  10. The influence of rill density on soil erosion against USLE-soil erosion methode

    OpenAIRE

    Rizalihadi, A.M.; Faimah, B.E.; Nazia, C.L.

    2013-01-01

    Land and water is one of the major natural resource which has an important role for human life. Exploitation of land in catchment areas that not correspond to its carrying capacity will cause damage. One of the effect is increassing the soil erosion. Continuous erosion will also lead to increased sediment transport in rivers that disrupt the ship navigation on estuary due sediment accumulation. At present, soil erosion is estimated using USLE method, which is only limited to the erosion in th...

  11. Saliva and dental erosion.

    Science.gov (United States)

    Buzalaf, Marília Afonso Rabelo; Hannas, Angélicas Reis; Kato, Melissa Thiemi

    2012-01-01

    Dental erosion is a multifactorial condition. The consideration of chemical, biological and behavioral factors is fundamental for its prevention and therapy. Among the biological factors, saliva is one of the most important parameters in the protection against erosive wear. This review discusses the role of salivary factors on the development of dental erosion. A search was undertaken on MeDLINe website for papers from 1969 to 2010. The keywords used in the research were "saliva", "acquired pellicle", "salivary flow", "salivary buffering capacity" and "dental erosion". Inclusion of studies, data extraction and quality assessment were undertaken independently and in duplicate by two members of the review team. Disagreements were solved by discussion and consensus or by a third party. Several characteristics and properties of saliva play an important role in dental erosion. Salivary clearance gradually eliminates the acids through swallowing and saliva presents buffering capacity causing neutralization and buffering of dietary acids. Salivary flow allows dilution of the acids. In addition, saliva is supersaturated with respect to tooth mineral, providing calcium, phosphate and fluoride necessary for remineralization after an erosive challenge. Furthermore, many proteins present in saliva and acquired pellicle play an important role in dental erosion. Saliva is the most important biological factor affecting the progression of dental erosion. Knowledge of its components and properties involved in this protective role can drive the development of preventive measures targeting to enhance its known beneficial effects.

  12. Saliva and dental erosion

    Directory of Open Access Journals (Sweden)

    Marília Afonso Rabelo Buzalaf

    2012-10-01

    Full Text Available Dental erosion is a multifactorial condition. The consideration of chemical, biological and behavioral factors is fundamental for its prevention and therapy. Among the biological factors, saliva is one of the most important parameters in the protection against erosive wear. Objective: This review discusses the role of salivary factors on the development of dental erosion. Material and Methods: A search was undertaken on MeDLINe website for papers from 1969 to 2010. The keywords used in the research were "saliva", "acquired pellicle", "salivary flow", "salivary buffering capacity" and "dental erosion". Inclusion of studies, data extraction and quality assessment were undertaken independently and in duplicate by two members of the review team. Disagreements were solved by discussion and consensus or by a third party. Results: Several characteristics and properties of saliva play an important role in dental erosion. Salivary clearance gradually eliminates the acids through swallowing and saliva presents buffering capacity causing neutralization and buffering of dietary acids. Salivary flow allows dilution of the acids. In addition, saliva is supersaturated with respect to tooth mineral, providing calcium, phosphate and fluoride necessary for remineralization after an erosive challenge. Furthermore, many proteins present in saliva and acquired pellicle play an important role in dental erosion. Conclusions: Saliva is the most important biological factor affecting the progression of dental erosion. Knowledge of its components and properties involved in this protective role can drive the development of preventive measures targeting to enhance its known beneficial effects.

  13. Should we perform an echocardiogram in hypertensive patients classified as having low and medium risk?

    Science.gov (United States)

    Suárez, Carmen; Villar, José; Martel, Nieves; Extremera, Blas Gil; Suliman, Najaty; Campo, Carlos; Castellanos, Victoriano; Liébana, Antonio; Rodilla, Enrique; Nieto, Javier; Velasco, Olga; Ruilope, Luis M

    2006-01-04

    Left ventricular hypertrophy is an important predictor of cardiovascular risk and its detection contributes to risk stratification. However, echocardiography is not a routine procedure and electrocardiography (ECG) underestimates its prevalence. To evaluate the prevalence of echocardiographic left ventricular hypertrophy in low and medium risk non-treated hypertensive subjects, in order to find out the percentage of them who would be reclassified as high risk patients. Cross-sectional, multicenter study was performed in hospital located hypertension units. An echocardiogram was performed in 197 previously untreated hypertensive patients, > 18 years, classified as having low (61%) or medium (39%) risk, according to the OMS/ISH classification. The presence of left ventricular hypertrophy was considered if left ventricular mass index was > or = 134 or 110 g/m(2) in men and women, respectively (Devereux criteria). A logistic regression analysis was performed to identify factors associated to left ventricular hypertrophy. The prevalence of left ventricular hypertrophy was 23.9% (95% CI:17.9-29.9), 25.6% in men and 22.6% in women. In the low risk group its prevalence was 20.7% and in medium risk group 29.5%. Factors associated to left ventricular hypertrophy were: years since the diagnosis of hypertension, OR:1.1 (95% CI:1.003-1.227); systolic blood pressure, OR:1.08 (95% CI:1.029-1.138); diastolic blood pressure, OR:0.9 (95% CI:0.882-0.991); and family history of cardiovascular disease, OR:4.3 (95% CI:1.52-12.18). These findings underline the importance of performing an echocardiogram in low and high risk untreated hypertensive patients in which treatment would otherwise be delayed for even one year.

  14. DISPERSION OF GLYPHOSATE IN SOILS UNDERGOING EROSION

    Directory of Open Access Journals (Sweden)

    Gorana Todorovic Rampazzo

    2010-08-01

    Full Text Available Different physical, chemical and biological processes influence the behaviour of organic contaminants in soils. A better understanding of the organic pollutant behaviour in soils would improve the environmental protection. One possible way for better attenuation of the risk of pollution in agriculture can be achieved through ta better-specified pesticide management based on the adaptation of the pesticide type and application rates to the specific environmental characteristics of the area of application. Nowadays, one of the actually most applied herbicide world wide is glyphosate. Glyphosate is highly water soluble and traces have been found in surface and groundwater systems. For a better understanding of the natural influence of erosion processes on glyphosate behaviour and dispersion under heavy rain conditions after application in the field, two erosion simulation experiments were conducted on two different locations in Austria with completely different soil types in September 2008. The results of the experiments showed that under normal practical conditions (e.g. no rainfall is expected immediatly after application, the potential adsorption capacity of the Kirchberg soil (Stagnic Cambisol, with about 16.000 ppm Fe-oxides is confirmed compared to the low adsorption Chernosem soil (about 8.000 ppm pedogenic Fe-oxides.  Considering the enormous difference in the run-off amounts between the two sites Pixendorf and Kirchberg soils it can be concluded how important the soil structural conditions and vegetation type and cover are for the risks of erosion and, as a consequence, pollution of neighbouring waters. In the rainfall experiments under comparable simulation conditions, the amount of run-off was about 10 times higher at Kirchberg, owing to its better infiltration rate, than at the Pixendorf site. Moreover, the total loss of glyphosate (NT+CT through run-off at the Kirchberg site was more than double that at Pixendorf, which confirms the

  15. Mapping Erosion and Salinity Risk Categories Using GIS and the Rangeland Hydrology Erosion Model

    Science.gov (United States)

    Up to fifteen percent of rangelands in the state of Utah in the United States are classified as being in severely eroding condition. Some of these degraded lands are located on saline, erodible soils of the Mancos Shale formation. This results in a disproportionate contribution of sediment, salinity...

  16. Increasing trends in rainfall-runoff erosivity in the Source Region of the Three Rivers, 1961-2012.

    Science.gov (United States)

    Wang, Yousheng; Cheng, Congcong; Xie, Yun; Liu, Baoyuan; Yin, Shuiqing; Liu, Yingna; Hao, Yanfang

    2017-08-15

    As the head source of the two longest rivers in China and the longest river in Southeast Asia, the East Qinghai-Tibetan Plateau (QTP) is experiencing increasing thaw snowmelt and more heavy precipitation events under global warming, which might lead to soil erosion risk. To understand the potential driving force of soil erosion and its relationship with precipitation in the context of climate change, this study analyzed long-term variations in annual rainfall-runoff erosivity, a climatic index of soil erosion, by using the Mann-Kendall statistical test and Theil and Sen's approach in the Source Region of the Three Rivers during 1961-2012. The results showed the followings: (i) increasing annual rainfall-runoff erosivity was observed over the past 52years, with a mean relative trend index (RT 1 ) value of 12.1%. The increasing trend was more obvious for the latest two decades: RT 1 was nearly three times larger than that over the entire period; (ii) more precipitation events and a higher precipitation amount were the major forces for the increasing rainfall-runoff erosivity; (iii) similar rising trends in sediment yields, which corresponded to rainfall-runoff erosivity under slightly increasing vegetation coverage in the study area, implied a large contribution of rainfall-runoff erosivity to the increasing sediment yields; and (iv) high warming rates increased the risk of soil destruction, soil erosion and sediment yields. Conservation measures, such as enclosing grassland, returning grazing land to grassland and rotation grazing since the 1980s, have maintained vegetation coverage and should be continued and strengthened. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Auto consolidated cohesive sediments erosion; Erosion des sediments cohesifs en autoconsolidation

    Energy Technology Data Exchange (ETDEWEB)

    Ternat, F

    2007-02-15

    Pollutants and suspended matters of a river can accumulate into the sedimentary column. Once deposited, they are submitted to self-weight consolidation processes, ageing and burying, leading to an increase of their erosion resistance. Pollutant fluxes can be related to sedimentary fluxes, determined by threshold laws. In this work, an erosion threshold model is suggested by introducing a cohesion force into the usual force balance. A model of cohesion is developed on the basis of interactions between argillaceous cohesive particles (clays), particularly the Van der Waals force, whose parameterization is ensured by means of granulometry and porosity. Artificial erosion experiments were performed in a recirculating erosion flume with natural cored sediments where critical shear stress measurements were performed. Other analyses provided granulometry and porosity. The results obtained constitute a good database for the literature. The model is then applied to the experimental conditions and gives good agreement with measurements. An example of the accounting for self-weight consolidation processes is finally suggested, before finishing on a Mohr like diagram dedicated to soft cohesive sediment erosion. (author)

  18. Prevalence and factors associated with dental erosion in individuals aged 12-30 years in a northeastern Brazilian city.

    Science.gov (United States)

    Luciano, Luanda Cristina O; Ferreira, Meire Coelho; Paschoal, Marco Aurelio

    2017-01-01

    Dental erosion in young individuals has increased significantly in recent years, due to changes in lifestyle. Thus, the present study investigated the prevalence and factors associated with dental erosion in individuals aged 12-30 years in the city of Imperatriz of Maranhão, Brazil. A cross-sectional study was conducted on 335 individuals who answered a questionnaire consisting of variables related to dental erosion. Afterwards, the individuals were subjected to clinical examinations and the basic erosive wear examination index was used to classify their teeth according to the presence and severity of dental erosion. Descriptive statistics, the chi-square test, Poisson univariate and multivariate regression were performed at 5% level of significance. The sample was characterized by 204 females (60.9%), the majority of whom were from 12 to 19 years of age (78.5%), among whom 28.7% presented dental erosion. Their monthly family income was from 1 to 3 minimum wages (56.4%). The variables that were significantly associated with the outcome were family income, chewing gum, and consumption of soft-drinks/juices before going to sleep ( p =0.03, p =0.001, and p =0.04, respectively). Individuals who chewed chewing gum were 2.27 times (95% CI =1.43-3.60) more likely to present dental erosion than those who did not chew gum. Individuals who ingested soft drinks or juices were 2.30 times (95% CI =1.30-4.10) more likely to present dental erosion. The prevalence of erosion reflected the need for programs of prevention and guidance for patients about the etiological factors of the disease.

  19. Immunohistochemical Study of p53 Expression in Patients with Erosive and Non-Erosive Oral Lichen Planus

    Science.gov (United States)

    Shiva, Atena; Zamanian, Ali; Arab, Shahin; Boloki, Mahsa

    2018-01-01

    Statement of the Problem: Oral lichen planus is a common mucocutaneous lesion with a chronic inflammatory process mediated by immune factors while a few cases of the disease become malignant. Purpose: This study aimed to determine the frequency of p53 marker as a tumor suppressor in patients with erosive and non-erosive oral lichen planus (OLP) by using immunohistochemical methods. Materials and Method: This descriptive cross-sectional study investigated the p53 expression in 16 erosive OLP, 16 non-erosive OLP samples, and 8 samples of normal oral mucosa through immunohistochemistry. The percentage of stained cells in basal and suprabasal layers, and inflammatory infiltrate were graded according to the degree of staining; if 0%, 50% of the cells were stained, they were considered as (-), (+), (++), (+++) and (++++), respectively. The obtained data was statistically analyzed and compared by using Chi square and Fisher’s exact test. Results: The mean percentage of p53 positive cells in erosive OLP (34.5±14.2) was considerably higher than that in non-erosive OLP (23.8±10.4) and normal mucosa (17.5±17). There was a significant difference among the three groups of erosive, non-erosive and control in terms of staining intensity. No significant difference existed between the patients’ age and sex in the two OLP groups. Conclusion: The increased incidence of p53 from normal mucosa to erosive OLP indicated the difference between biological behavior of erosive and non-erosive OLP. It can be claimed that the erosive OLP has great premalignant potential compared with the non-erosive one.

  20. Dental erosion -- changing prevalence? A review of British National childrens' surveys.

    Science.gov (United States)

    Nunn, J H; Gordon, P H; Morris, A J; Pine, C M; Walker, A

    2003-03-01

    To investigate the change in the prevalence of dental erosion, over time, by a review of the data from the published national dental surveys of young people in the UK. A subsidiary objective was to investigate the relationship between erosion and possible associated risk factors. The review was based on cross-sectional prevalence studies incorporating a clinical dental examination and structured interviews. The data were collated from the 1993 UK childrens' dental health survey and the dental report of the two National Diet and Nutrition Surveys (NDNS) of children aged 1(1/2)-4(1/2) in 1992/3 and 4-18 years in 1996/7. The criteria used for data collection were comparable between the three different studies. Comparing the data from the different studies, the prevalence of erosion was seen to increase from the time of the childrens' dental health survey in 1993 and the NDNS study of 4-18-year-olds in 1996/7. There was a trend towards a higher prevalence of erosion in children aged between 3(1/2) and 4(1/2) and in those who consumed carbonated drinks on most days compared with toddlers consuming these drinks less often. Drinks overnight were associated with an increased prevalence of erosion. More 4-6-year-olds with reported symptoms of gastro-oesophageal reflux had erosion compared with symptom-free children. On multivariate analysis, the strongest independent association with erosion was geography, with children living in the North having twice the odds of having erosion compared with those in London and the South-east. Comparing prevalence data from cross-sectional national studies indicates that dental erosion increases between different age cohorts of young people over time. Dietary associations with erosion are present but weak. Similarly, there is an association apparent between erosion, symptoms of gastro-oesophageal reflux and socio-demographic variables such as region of domicile, social class, and receipt of social benefits.

  1. Ecological site-based assessments of wind and water erosion: informing accelerated soil erosion management in rangelands

    Science.gov (United States)

    Webb, Nicholas P.; Herrick, Jeffrey E.; Duniway, Michael C.

    2014-01-01

    Accelerated soil erosion occurs when anthropogenic processes modify soil, vegetation or climatic conditions causing erosion rates at a location to exceed their natural variability. Identifying where and when accelerated erosion occurs is a critical first step toward its effective management. Here we explore how erosion assessments structured in the context of ecological sites (a land classification based on soils, landscape setting and ecological potential) and their vegetation states (plant assemblages that may change due to management) can inform systems for reducing accelerated soil erosion in rangelands. We evaluated aeolian horizontal sediment flux and fluvial sediment erosion rates for five ecological sites in southern New Mexico, USA, using monitoring data and rangeland-specific wind and water erosion models. Across the ecological sites, plots in shrub-encroached and shrub-dominated vegetation states were consistently susceptible to aeolian sediment flux and fluvial sediment erosion. Both processes were found to be highly variable for grassland and grass-succulent states across the ecological sites at the plot scale (0.25 Ha). We identify vegetation thresholds that define cover levels below which rapid (exponential) increases in aeolian sediment flux and fluvial sediment erosion occur across the ecological sites and vegetation states. Aeolian sediment flux and fluvial erosion in the study area can be effectively controlled when bare ground cover is 100 cm in length is less than ~35%. Land use and management activities that alter cover levels such that they cross thresholds, and/or drive vegetation state changes, may increase the susceptibility of areas to erosion. Land use impacts that are constrained within the range of natural variability should not result in accelerated soil erosion. Evaluating land condition against the erosion thresholds identified here will enable identification of areas susceptible to accelerated soil erosion and the development of

  2. Ecological site‐based assessments of wind and water erosion: informing accelerated soil erosion management in rangelands.

    Science.gov (United States)

    Webb, Nicholas P; Herrick, Jeffrey E; Duniway, Michael C

    Accelerated soil erosion occurs when anthropogenic processes modify soil, vegetation, or climatic conditions causing erosion rates at a location to exceed their natural variability. Identifying where and when accelerated erosion occurs is a critical first step toward its effective management. Here we explored how erosion assessments structured in the context of ecological sites (a land classification based on soils, landscape setting, and ecological potential) and their vegetation states (plant assemblages that may change due to management) can inform systems for reducing accelerated soil erosion in rangelands. We evaluated aeolian horizontal sediment flux and fluvial sediment erosion rates for five ecological sites in southern New Mexico, USA, using monitoring data and rangeland-specific wind and water erosion models. Across the ecological sites, plots in shrub-encroached and shrub-dominated vegetation states were consistently susceptible to aeolian sediment flux and fluvial sediment erosion. Both processes were found to be highly variable for grassland and grass–succulent states across the ecological sites at the plot scale (0.25 ha). We identified vegetation thresholds that define cover levels below which rapid (exponential) increases in aeolian sediment flux and fluvial sediment erosion occur across the ecological sites and vegetation states. Aeolian sediment flux and fluvial erosion in the study area could be effectively controlled when bare ground cover was 100 cm in length was less than ∼35%. Land use and management activities that alter cover levels such that they cross thresholds, and/or drive vegetation state changes, may increase the susceptibility of areas to erosion. Land use impacts that are constrained within the range of natural variability should not result in accelerated soil erosion. Evaluating land condition against the erosion thresholds identified here will enable identification of areas susceptible to accelerated soil erosion and the

  3. Soil Erosion as a stochastic process

    Science.gov (United States)

    Casper, Markus C.

    2015-04-01

    The main tools to provide estimations concerning risk and amount of erosion are different types of soil erosion models: on the one hand, there are empirically based model concepts on the other hand there are more physically based or process based models. However, both types of models have substantial weak points. All empirical model concepts are only capable of providing rough estimates over larger temporal and spatial scales, they do not account for many driving factors that are in the scope of scenario related analysis. In addition, the physically based models contain important empirical parts and hence, the demand for universality and transferability is not given. As a common feature, we find, that all models rely on parameters and input variables, which are to certain, extend spatially and temporally averaged. A central question is whether the apparent heterogeneity of soil properties or the random nature of driving forces needs to be better considered in our modelling concepts. Traditionally, researchers have attempted to remove spatial and temporal variability through homogenization. However, homogenization has been achieved through physical manipulation of the system, or by statistical averaging procedures. The price for obtaining this homogenized (average) model concepts of soils and soil related processes has often been a failure to recognize the profound importance of heterogeneity in many of the properties and processes that we study. Especially soil infiltrability and the resistance (also called "critical shear stress" or "critical stream power") are the most important empirical factors of physically based erosion models. The erosion resistance is theoretically a substrate specific parameter, but in reality, the threshold where soil erosion begins is determined experimentally. The soil infiltrability is often calculated with empirical relationships (e.g. based on grain size distribution). Consequently, to better fit reality, this value needs to be

  4. Determination of soil erosion risk in the Mustafakemalpasa River Basin, Turkey, using the revised universal soil loss equation, geographic information system, and remote sensing.

    Science.gov (United States)

    Ozsoy, Gokhan; Aksoy, Ertugrul; Dirim, M Sabri; Tumsavas, Zeynal

    2012-10-01

    -geographic information system (GIS) combination and the measured values from the Dolluk sediment gauge station shows that the potential soil erosion risk of the MKP River Basin can be estimated correctly and reliably using the RUSLE function generated in a GIS environment.

  5. Gene-expression Classifier in Papillary Thyroid Carcinoma

    DEFF Research Database (Denmark)

    Londero, Stefano Christian; Jespersen, Marie Louise; Krogdahl, Annelise

    2016-01-01

    BACKGROUND: No reliable biomarker for metastatic potential in the risk stratification of papillary thyroid carcinoma exists. We aimed to develop a gene-expression classifier for metastatic potential. MATERIALS AND METHODS: Genome-wide expression analyses were used. Development cohort: freshly...

  6. Quantifying accelerated soil erosion through ecological site-based assessments of wind and water erosion

    Science.gov (United States)

    This work explores how organising soil erosion assessments using established groupings of similar soils (ecological sites) can inform systems for managing accelerated soil erosion. We evaluated aeolian sediment transport and fluvial erosion rates for five ecological sites in southern New Mexico, USA...

  7. Recent and future rainfall erosivity on the territory of the Czech Republic

    Science.gov (United States)

    Krasa, Josef; Stredova, Hana; Stepanek, Petr; Hanel, Martin; Dostal, Tomas; Novotny, Ivan

    2015-04-01

    Water erosion is a main factor of degradation of soils used for agriculture in the Czech Republic. For landscape conservation purposes the soil erosion risk is defined here mostly by USLE (Wischmeier and Smith, 1978). Within USLE the precipitation impact on erosion is a function of rainfall kinetic energy and intensity represented by R-factor. In the Czech Republic historically and recently several research teams have analyzed rainfall data to assess R-factor. Till now not many European countries have performed detailed spatially distributed analyses of rain erosivities. Most studies use only simplified methods based on long-term rainfall averages or databases of only several station-datasets. The most recent study on rainfall erosivity spatial distribution over the Czech Republic was based on digital rain gauge data from automatic stations of the Czech Hydrometeorogical Institute. The erosive rains were derived from continuous 1 minute step 10-year rainfall data (2003-2012) from 245 stations. Based on the research recent annual R-factor values in the stations vary from 37 to 239 [N.h-1] (values over 100 are located in mountain regions with minimum of agricultural land). Average value is 69 [N.h-1.year-1]. For the Czech Republic the future prediction is based on 10km resolution ALADIN/CZ regional climate model. Within the EU FP6 project CECILIA it was coupled with GCM ARPEGE to provide a projection of future climate in two time slices, 2021-2050 and 2071-2100, according to the IPCC A1B emission scenario. Daily precipitation volumes and percentiles of maximal events allowed authors to develop R-factor maps of present and future scenarios. Based on the analyses we can conclude that average value for the whole territory of the Czech Republic will remain close to 70 [N.h-1.year-1] or even decrease for 2071-2100, but we can expect significant changes (30-40 % rise or decrease) for several large agricultural regions (eg. Southern Moravia). These changes will have impact

  8. Rill erosion rates in burned forests

    Science.gov (United States)

    Joseph W. Wagenbrenner; Peter R. Robichaud

    2011-01-01

    Introduction Wildfires often produce large increases in runoff and erosion rates (e.g., Moody and Martin, 2009), and land managers need to predict the frequency and magnitude of postfire erosion to determine the needs for hazard response and possible erosion mitigation to reduce the impacts of increased erosion on public safety and valued resources. The Water Erosion...

  9. Evaluation of the serum zinc level in erosive and non-erosive oral lichen planus.

    Science.gov (United States)

    Gholizadeh, N; Mehdipour, M; Najafi, Sh; Bahramian, A; Garjani, Sh; Khoeini Poorfar, H

    2014-06-01

    Lichen planus is a chronic inflammatory immunologic-based disease involving skin and mucosa. This disease is generally divided into two categories: erosive and non-erosive. Many etiologic factors are deliberated regarding the disease; however, the disorders of immune system and the role of cytotoxic T-lymphocytes and monocytes are more highlighted. Zinc is an imperative element for the growth of epithelium and its deficiency induces the cytotoxic activity of T-helper2 cells, which seems to be associated with lichen planus. This study was aimed to evaluate the levels of serum zinc in erosive and non-erosive oral lichen planus (OLP) and to compare it with the healthy control group to find out any feasible inference. A total of 22 patients with erosive oral lichen planus, 22 patients with non erosive OLP and 44 healthy individuals as the control group were recruited in this descriptive-comparative study. All the participants were selected from the referees to the department of oral medicine, school of dentistry, Tabriz University of Medical Sciences. Serum zinc level was examined for all the individuals with liquid-stat kit (Beckman Instruments Inc.; Carlsbad, CA). Data were analyzed by adopting the ANOVA and Tukey tests, using SPSS 16 statistical software. The mean age of patients with erosive and non-erosive LP was 41.7 and 41.3 years, respectively. The mean age of the healthy control group was 34.4 years .The mean serum zinc levels in the erosive and non erosive lichen planus groups and control groups were 8.3 (1.15), 11.15 (0.92) and 15.74 (1.75) μg/dl respectively. The difference was statistically significant (poral lichen planus. This finding may probably indicate the promising role of zinc in development of oral lichen planus.

  10. Modeling soil erosion in a watershed

    OpenAIRE

    Lanuza, R.

    1999-01-01

    Most erosion models have been developed based on a plot scale and have limited application to a watershed due to the differences in aerial scale. In order to address this limitation, a GIS-assisted methodology for modeling soil erosion was developed using PCRaster to predict the rate of soil erosion at watershed level; identify the location of erosion prone areas; and analyze the impact of landuse changes on soil erosion. The general methodology of desktop modeling or soil erosion at watershe...

  11. Forest soil erosion prediction as influenced by wildfire and roads

    Science.gov (United States)

    Cao, L.; Brooks, E. S.; Elliot, W.

    2017-12-01

    Following a wildfire, the risk of erosion is greatly increased. Forest road networks may change the underlying topography and alter natural flow paths. Flow accumulation and energy can be redistributed by roads and alter soil erosion processes. A LiDAR (Light Detection and Ranging) DEM makes it possible to quantify road topography, and estimate how roads influence surface runoff and sediment transport in a fire-disturbed watershed. With GIS technology and a soil erosion model, this study was carried out to evaluate the effect of roads on erosion and sediment yield following the Emerald Fire southwest of Lake Tahoe. The GeoWEPP model was used to estimate onsite erosion and offsite sediment delivery from each hillslope polygon and channel segment before and after fire disturbance in part of the burned area. The GeoWEPP flow path method was used to estimate the post-fire erosion rate of each GIS pixel. A 2-m resolution LiDAR DEM was used as the terrain layer. The Emerald Fire greatly increased onsite soil loss and sediment yields within the fire boundary. Following the fire, 78.71% of the burned area had predicted sediment yields greater than 4 Mg/ha/yr, compared to the preburn condition when 65.3% of the study area was estimated to generate a sediment yield less than 0.25 Mg/ha/yr. Roads had a remarkable influence on the flow path simulation and sub-catchments delineation, affecting sediment transport process spatially. Road segments acted as barriers that intercepted overland runoff and reduced downslope flow energy accumulation, therefore reducing onsite soil loss downslope of the road. Roads also changed the boundary of sub-catchment and defined new hydrological units. Road segments can transport sediment from one sub-catchment to another. This in turn leads to the redistribution of sediment and alters sediment yield for some sub-catchments. Culverts and road drain systems are of vital importance in rerouting runoff and sediment. Conservation structures can be

  12. Repair, Evaluation, Maintenance, and Rehabilitation Research Program. Geotechnical Aspects of Rock Erosion in Emergency Spillway Channels

    Science.gov (United States)

    1986-08-01

    8217 flooring unlined spillway channels. 115. Rippability was proposed by Weaver (1975) as a rock mass classifi- cation system that enables the assessment...geological. features which govern the as- sessment of rippability are rock type, haidness, weathering, stcucture, and fabric. Saismic P-wave velocity...channel. Rippability should be combined with a factor 84 that describes lithostratigraphic continuity in order to derive the erosion potential of the

  13. Scales and erosion

    Science.gov (United States)

    There is a need to develop scale explicit understanding of erosion to overcome existing conceptual and methodological flaws in our modelling methods currently applied to understand the process of erosion, transport and deposition at the catchment scale. These models need to be based on a sound under...

  14. Mapping Erosion Risk in California's Rangelands Using the Universal Soil Loss Equation (USLE)

    Science.gov (United States)

    Salls, W. B.; O'Geen, T. T.

    2015-12-01

    Soil loss constitutes a multi-faceted problem for agriculture: in addition to reducing soil fertility and crop yield, it compromises downstream water quality. Sediment itself is a major issue for aquatic ecosystems, but also serves as a vector for transporting nutrients, pesticides, and pathogens. Rangelands are thought to be a contributor to water quality degradation in California, particularly in the northern Coast Range. Though total maximum daily loads (TMDLs) have been imposed in some watersheds, and countless rangeland water quality outreach activities have been conducted, the connection between grazing intensity recommendations and changes in water quality is poorly understood at the state level. This disconnect gives rise to poorly informed regulations and discourages adoption of best management practices by ranchers. By applying the Universal Soil Loss Equation (USLE) at a statewide scale, we highlighted areas most prone to erosion. We also investigated how two different grazing intensity scenarios affect modeled soil loss. Geospatial data layers representing the USLE parameters—rainfall erosivity, soil erodibility, slope length and steepness, and cover—were overlaid to model annual soil loss. Monitored suspended sediment data from a small North Coast watershed with grazing as the predominant land use was used to validate the model. Modeled soil loss values were nearly one order of magnitude higher than monitored values; average soil loss feeding the downstream-most site was modeled at 0.329 t ha-1 yr-1, whereas storm-derived sediment passing the site over two years was calculated to be 0.037 t ha-1 yr-1. This discrepancy may stem from the fact that the USLE models detached sediment, whereas stream monitoring reflects sediment detached and subsequently transported to the waterway. Preliminary findings from the statewide map support the concern that the North Coast is particularly at risk given its combination of intense rain, erodible soils, and

  15. Potential Risk Assessment of Mountain Torrent Disasters on Sloping Fields in China

    Science.gov (United States)

    GAO, X.

    2017-12-01

    China's sloping fields have the problems of low production and serious soil erosion, and mountain torrent disasters will bring more serious soil and water loss to traditional extensive exploitation of sloping field resources. In this paper, China's sloping fields were classified into three grades, such as slightly steep, steep and very steep grade. According to the geological hazards prevention and control regulation, the historical data of China's mountain torrent disasters were spatially interpolated and divided into five classes, such as extremely low, low, middle, high and extremely high level. And the risk level map of mountain torrents was finished in ArcGIS. By using overlaying analysis on sloping fields and risk level map, the potential risk regionalization map of sloping fields in various slope grades was obtained finally. The results shows that the very steep and steep sloping fields are mainly distributed in the first or second stage terraces in China. With the increase of hazard risk level, the area of sloping fields decreases rapidly and the sloping fields in extremely low and low risk levels of mountain torrents reach 98.9%. With the increase of slope grade, the area of sloping fields in various risk levels also declines sharply. The sloping fields take up approximately 60 65% and 26 30% in slightly steep and steep grade areas separately at different risk level. The risk regionalization map can provide effective information for returning farmland to forests or grassland and reducing water and soil erosion of sloping fields in the future.

  16. Does a more sophisticated storm erosion model improve probabilistic erosion estimates?

    NARCIS (Netherlands)

    Ranasinghe, R.W.M.R.J.B.; Callaghan, D.; Roelvink, D.

    2013-01-01

    The dependency between the accuracy/uncertainty of storm erosion exceedance estimates obtained via a probabilistic model and the level of sophistication of the structural function (storm erosion model) embedded in the probabilistic model is assessed via the application of Callaghan et al.'s (2008)

  17. Prediction of Soil Erosion Rates in Japan where Heavily Forested Landscape with Unstable Terrain

    Science.gov (United States)

    Nanko, K.; Oguro, M.; Miura, S.; Masaki, T.

    2016-12-01

    Soil is fundamental for plant growth, water conservation, and sustainable forest management. Multidisciplinary interest in the role of the soil in areas such as biodiversity, ecosystem services, land degradation, and water security has been growing (Miura et al., 2015). Forest is usually protective land use from soil erosion because vegetation buffers rainfall power and erosivity. However, some types of forest in Japan show high susceptibility to soil erosion due to little ground cover and steep slopes exceeding thirty degree, especially young Japanese cypress (Chamaecyparis obtusa) plantations (Miura et al., 2002). This is a critical issue for sustainable forest management because C. obtusaplantations account for 10% of the total forest coverage in Japan (Forestry Agency, 2009). Prediction of soil erosion rates on nationwide scale is necessary to make decision for future forest management plan. To predict and map soil erosion rates across Japan, we applied three soil erosion models, RUSLE (Revised Universal Soil Loss Equation, Wischmeier and Smith, 1978), PESERA (Pan-European Soil Erosion Risk Assessment, Kirkby et al., 2003), and RMMF (Revised Morgan-Morgan-Finney, Morgan, 2001). The grid scale is 1-km. RUSLE and PESERA are most widely used erosion models today. RMMF includes interactions between rainfall and vegetation, such as canopy interception and ratio of canopy drainage in throughfall. Evaporated rainwater by canopy interception, generally accounts for 15-20% in annual rainfall, does not contribute soil erosion. Whereas, larger raindrops generated by canopy drainage produced higher splash erosion rates than gross rainfall (Nanko et al., 2008). Therefore, rainfall redistribution process in canopy should be considered to predict soil erosion rates in forested landscape. We compared the results from three erosion models and analyze the importance of environmental factors for the prediction of soil erosion rates. This research was supported by the Environment

  18. Effectiveness of the GAEC standard of cross compliance retain terraces on soil erosion control

    Directory of Open Access Journals (Sweden)

    Paolo Bazzoffi

    2011-08-01

    Full Text Available The GAEC standard retain terraces of cross compliance prohibits farmers the elimination of existing terraces, with the aim to ensure the protection of soil from erosion. In the Italian literature there are not field studies to quantify the effects of the elimination or degradation of terraces on soil erosion. Therefore, the modeling approach was chosen and applied in a scenario analysis to evaluate increasing levels of degradation of stone wall terraces. The study was conducted on two sample areas: Lamole (700.8 ha, Tuscany and Costaviola (764.73 ha, Calabria with contrasting landscapes. The Universal Soil Loss Equation model (USLE was applied in the comparative assessment of the soil erosion risk (Mg . ha-1 . yr-1, by simulating five increasing intensity of terrace degradation, respectively: conserved partially damaged, very damaged, partially removed, removed, each of which corresponding to different values of the indexes of verification in case of infringement to GAEC standard provided for by the AGEA rules which have come into force since December 2009 (Agency for Agricultural Payments. To growing intensity of degradation, a progressive loss of efficacy of terraces was attributed by increasing the values of the LS factor (length and slope of USLE in relation with the local modification of the length and steepness of the slope between adjacent terraces. Basically, it was simulated the gradual return to the natural morphology of the slope. The results of the analysis showed a significant increase in erosion in relationship with increasing degradation of terraces. Furthermore, it is possible to conclude that the GAEC standard retain terraces is very effective with regard to the primary objective of reducing erosion. A further statistical analysis was performed to test the protective value of terraces against soil erosion in areas where agriculture was abandoned. The analysis was carried out by comparing the specific risk of erosion (Mg . ha-1

  19. Classifying At-Risk High School Youth: The Influence of Exposure to Community Violence and Protective Factors on Academic and Health Outcomes

    Science.gov (United States)

    Solberg, V. Scott H.; Carlstom, Aaron H.; Howard, Kimberly A. S.; Jones, Janice E.

    2007-01-01

    Using cluster analysis, 789 predominately Latino and African American high school youth were classified into varying academic at-risk profiles using self-reported levels of academic confidence, motivation to attend school, perceived family support, connections with teachers and peers, and exposure to violence. Six clusters emerged, 5 of which were…

  20. LIDAR data to support coastal erosion analysis: the Conero study case

    Science.gov (United States)

    Calligaro, Simone; Sofia, Giulia; Guarnieri, Alberto; Tarolli, Paolo

    2013-04-01

    In the last decades, the topic of coastal erosion and the derived risk have been subject of a growing interest for public authorities and researchers. Recent major natural events, such as hurricanes, tsunamis, and sea level rising, called the attention of media and society, underlining serious concerns about such problems. In a high-density populated country such as Italy, where tourism is one of the major economic activities, the coastal erosion is really a critical issue. In April 2010, along a reach of the coast of Ventotene Island, two young students tragically died, killed by a rock fall. This event dramatically stressed public authorities about the effectiveness of structural and non-structural measures for the mitigation of such phenomena. It is clear that an improving of the actual knowledge about coastal erosion is needed, especially to monitor such events and to set alert systems. In the last few years, airborne LIDAR technology led to a dramatic increase in terrain information. Airborne LiDAR and Terrestrial Laser Scanner (TLS) derived high-resolution Digital Terrain Models (DTMs) have opened avenues for hydrologic and geomorphologic studies (Tarolli et al., 2009). In general, all the main surface processes signatures are correctly recognized using a DTM with cell sizes of 1 m. Having said that, some sub-meter grid sizes may be more suitable in those situations where the analysis of micro topography related to micro changes due to slope failures is critical for risk assessment, and the Terrestrial Laser Scanner (TLS) has been proven to be a useful tool for such detailed field survey. The acquired elevation data with TLS allow to derive a centimeters high quality DTMs. The possibility to detect in detail the slope failures signatures results in a better understanding and mapping of the erosion susceptibility, and of those areas where slope failures are more likely to happen. In addition, these information can be also considered as the basis to develop

  1. Buffer erosion in dilute groundwater

    International Nuclear Information System (INIS)

    Schatz, T.; Kanerva, N.; Martikainen, J.; Sane, P.; Olin, M.; Seppaelae, A.; Koskinen, K.

    2013-08-01

    One scenario of interest for repository safety assessment involves the loss of bentonite buffer material in contact with dilute groundwater flowing through a transmissive fracture interface. In order to examine the extrusion/erosion behavior of bentonite buffer material under such circumstances, a series of experiments were performed in a flow-through, 1 mm aperture, artificial fracture system. These experiments covered a range of solution chemistry (salt concentration and composition), material composition (sodium montmorillonite and admixtures with calcium montmorillonite), and flow velocity conditions. No erosion was observed for sodium montmorillonite against solution compositions from 0.5 g/L to 10 g/L NaCl. No erosion was observed for 50/50 calcium/sodium montmorillonite against 0.5 g/L NaCl. Erosion was observed for both sodium montmorillonite and 50/50 calcium/sodium montmorillonite against solution compositions ≤ 0.25 g/L NaCl. The calculated erosion rates for the tests with the highest levels of measured erosion, i.e., the tests run under the most dilute conditions (ionic strength (IS) < ∼1 mM), were well-correlated to flow velocity, whereas the calculated erosion rates for the tests with lower levels of measured erosion, i.e., the tests run under somewhat less dilute conditions (∼1 mM < IS < ∼4 mM), were not similarly correlated indicating that material and solution composition can significantly affect erosion rates. In every experiment, both erosive and non-erosive, emplaced buffer material extruded into the fracture and was observed to be impermeable to water flowing in the fracture effectively forming an extended diffusive barrier around the intersecting fracture/buffer interface. Additionally, a model which was developed previously to predict the rate of erosion of bentonite buffer material in low ionic strength water in rock fracture environments was applied to three different cases: sodium montmorillonite expansion in a vertical tube, a

  2. Classifying a smoker scale in adult daily and nondaily smokers.

    Science.gov (United States)

    Pulvers, Kim; Scheuermann, Taneisha S; Romero, Devan R; Basora, Brittany; Luo, Xianghua; Ahluwalia, Jasjit S

    2014-05-01

    Smoker identity, or the strength of beliefs about oneself as a smoker, is a robust marker of smoking behavior. However, many nondaily smokers do not identify as smokers, underestimating their risk for tobacco-related disease and resulting in missed intervention opportunities. Assessing underlying beliefs about characteristics used to classify smokers may help explain the discrepancy between smoking behavior and smoker identity. This study examines the factor structure, reliability, and validity of the Classifying a Smoker scale among a racially diverse sample of adult smokers. A cross-sectional survey was administered through an online panel survey service to 2,376 current smokers who were at least 25 years of age. The sample was stratified to obtain equal numbers of 3 racial/ethnic groups (African American, Latino, and White) across smoking level (nondaily and daily smoking). The Classifying a Smoker scale displayed a single factor structure and excellent internal consistency (α = .91). Classifying a Smoker scores significantly increased at each level of smoking, F(3,2375) = 23.68, p smoker identity, stronger dependence on cigarettes, greater health risk perceptions, more smoking friends, and were more likely to carry cigarettes. Classifying a Smoker scores explained unique variance in smoking variables above and beyond that explained by smoker identity. The present study supports the use of the Classifying a Smoker scale among diverse, experienced smokers. Stronger endorsement of characteristics used to classify a smoker (i.e., stricter criteria) was positively associated with heavier smoking and related characteristics. Prospective studies are needed to inform prevention and treatment efforts.

  3. Dynamics of soil organic carbon and microbial biomass carbon in relation to water erosion and tillage erosion.

    Science.gov (United States)

    Xiaojun, Nie; Jianhui, Zhang; Zhengan, Su

    2013-01-01

    Dynamics of soil organic carbon (SOC) are associated with soil erosion, yet there is a shortage of research concerning the relationship between soil erosion, SOC, and especially microbial biomass carbon (MBC). In this paper, we selected two typical slope landscapes including gentle and steep slopes from the Sichuan Basin, China, and used the (137)Cs technique to determine the effects of water erosion and tillage erosion on the dynamics of SOC and MBC. Soil samples for the determination of (137)Cs, SOC, MBC and soil particle-size fractions were collected on two types of contrasting hillslopes. (137)Cs data revealed that soil loss occurred at upper slope positions of the two landscapes and soil accumulation at the lower slope positions. Soil erosion rates as well as distribution patterns of the erosion is the major process of soil redistribution in the gentle slope landscape, while tillage erosion acts as the dominant process of soil redistribution in the steep slope landscape. In gentle slope landscapes, both SOC and MBC contents increased downslope and these distribution patterns were closely linked to soil redistribution rates. In steep slope landscapes, only SOC contents increased downslope, dependent on soil redistribution. It is noticeable that MBC/SOC ratios were significantly lower in gentle slope landscapes than in steep slope landscapes, implying that water erosion has a negative effect on the microbial biomass compared with tillage erosion. It is suggested that MBC dynamics are closely associated with soil redistribution by water erosion but independent of that by tillage erosion, while SOC dynamics are influenced by soil redistribution by both water erosion and tillage erosion.

  4. Erhversbetinget erosion?

    DEFF Research Database (Denmark)

    Dige, Irene; Gjørup, Hans; Nyvad, Bente

    2012-01-01

    Baggrund – I forbindelse med dental erosion er en grundig udredning af patienten vigtig, således at årsagen til erosionernes opståen findes, og der kan iværksættes adækvat forebyggende indsats. En sådan udredning er ikke mindst vigtig, når arbejdsmiljøet mistænkes. Patienttilfælde – En 30-årig...... arbejdsskade, men ikke anerkendt, da erosioner ikke er optaget på Arbejdsskadestyrelsens liste over erhvervssygdomme. En systematisk registrering af lignende tilfælde kunne imidlertid på sigt ændre retspraksis for fremtidige patienter med arbejdsbetinget erosion....... patient, der arbejder som pladesmed, blev henvist til Landsdels- og Videnscenter, Århus Sygehus, med henblik på udredning af patientens kraftige slid. Patienten udviste ikke-alderssvarende tandslid af emalje og dentin svarende til erosion forårsaget af syredampe i arbejdsmiljøet, muligvis forstærket af...

  5. Regional soil erosion assessment in Slovakia using modelling and farmer's participation

    DEFF Research Database (Denmark)

    Kenderessy, Pavol; Veihe, Anita

    with cereals, sunflowers and corn and is characterised by poor cultivation practices and use of fertilizers leading to land degradation. As a first step, the initial raster-based modelling of soil loss and deposition has provided acceptable and realistic values. The predicted spatial patterns of erosion...... for erosion risk assessments at the landscape scale in Slovakia using a combination of quantitative and qualitative methods for assessing spatial prediction patterns. The model was set up for the Paríž catchment (239.93 km2) in south-western Slovakia. The area has been intensively cultivated primarily...... are now being identified using farmer participation to ensure that the ‘correct’ hot spot areas are being identified. In the end, scenarios will be set up to assess the effect of farming practices and/or conservation measures on soil erosion rates in the area....

  6. Soil erosion evolution and spatial correlation analysis in a typical karst geomorphology using RUSLE with GIS

    Science.gov (United States)

    Zeng, Cheng; Wang, Shijie; Bai, Xiaoyong; Li, Yangbing; Tian, Yichao; Li, Yue; Wu, Luhua; Luo, Guangjie

    2017-07-01

    Although some scholars have studied soil erosion in karst landforms, analyses of the spatial and temporal evolution of soil erosion and correlation analyses with spatial elements have been insufficient. The lack of research has led to an inaccurate assessment of environmental effects, especially in the mountainous area of Wuling in China. Soil erosion and rocky desertification in this area influence the survival and sustainability of a population of 0.22 billion people. This paper analyzes the spatiotemporal evolution of soil erosion and explores its relationship with rocky desertification using GIS technology and the revised universal soil loss equation (RUSLE). Furthermore, this paper analyzes the relationship between soil erosion and major natural elements in southern China. The results are as follows: (1) from 2000 to 2013, the proportion of the area experiencing micro-erosion and mild erosion was at increasing risk in contrast to areas where moderate and high erosion are decreasing. The area changes in this time sequence reflect moderate to high levels of erosion tending to convert into micro-erosion and mild erosion. (2) The soil erosion area on the slope, at 15-35°, accounted for 60.59 % of the total erosion area, and the corresponding soil erosion accounted for 40.44 %. (3) The annual erosion rate in the karst region decreased much faster than in the non-karst region. Soil erosion in all of the rock outcrop areas indicates an improving trend, and dynamic changes in soil erosion significantly differ among the various lithological distribution belts. (4) The soil erosion rate decreased in the rocky desertification regions, to below moderate levels, but increased in the severe rocky desertification areas. The temporal and spatial variations in soil erosion gradually decreased in the study area. Differences in the spatial distribution between lithology and rocky desertification induced extensive soil loss. As rocky desertification became worse, the erosion

  7. Soil erosion evolution and spatial correlation analysis in a typical karst geomorphology using RUSLE with GIS

    Directory of Open Access Journals (Sweden)

    C. Zeng

    2017-07-01

    Full Text Available Although some scholars have studied soil erosion in karst landforms, analyses of the spatial and temporal evolution of soil erosion and correlation analyses with spatial elements have been insufficient. The lack of research has led to an inaccurate assessment of environmental effects, especially in the mountainous area of Wuling in China. Soil erosion and rocky desertification in this area influence the survival and sustainability of a population of 0.22 billion people. This paper analyzes the spatiotemporal evolution of soil erosion and explores its relationship with rocky desertification using GIS technology and the revised universal soil loss equation (RUSLE. Furthermore, this paper analyzes the relationship between soil erosion and major natural elements in southern China. The results are as follows: (1 from 2000 to 2013, the proportion of the area experiencing micro-erosion and mild erosion was at increasing risk in contrast to areas where moderate and high erosion are decreasing. The area changes in this time sequence reflect moderate to high levels of erosion tending to convert into micro-erosion and mild erosion. (2 The soil erosion area on the slope, at 15–35°, accounted for 60.59 % of the total erosion area, and the corresponding soil erosion accounted for 40.44 %. (3 The annual erosion rate in the karst region decreased much faster than in the non-karst region. Soil erosion in all of the rock outcrop areas indicates an improving trend, and dynamic changes in soil erosion significantly differ among the various lithological distribution belts. (4 The soil erosion rate decreased in the rocky desertification regions, to below moderate levels, but increased in the severe rocky desertification areas. The temporal and spatial variations in soil erosion gradually decreased in the study area. Differences in the spatial distribution between lithology and rocky desertification induced extensive soil loss. As rocky desertification

  8. Effect of Abdominal Visceral Fat Change on Regression of Erosive Esophagitis: Prospective Cohort Study.

    Science.gov (United States)

    Nam, Su Youn; Kim, Young Woo; Park, Bum Joon; Ryu, Kum Hei; Kim, Hyun Boem

    2018-05-04

    Although abdominal visceral fat has been associated with erosive esophagitis in cross-sectional studies, there are few data on the longitudinal effect. We evaluated the effects of abdominal visceral fat change on the regression of erosive esophagitis in a prospective cohort study. A total of 163 participants with erosive esophagitis at baseline were followed up at 34 months and underwent esophagogastroduodenoscopy and computed tomography at both baseline and follow-up. The longitudinal effects of abdominal visceral fat on the regression of erosive esophagitis were evaluated using relative risk (RR) and 95% confidence intervals (CIs). Regression was observed in approximately 49% of participants (n=80). The 3rd (RR, 0.13; 95% CI, 0.02 to 0.71) and 4th quartiles (RR, 0.07; 95% CI, 0.01 to 0.38) of visceral fat at follow-up were associated with decreased regression of erosive esophagitis. The highest quartile of visceral fat change reduced the probability of the regression of erosive esophagitis compared to the lowest quartile (RR, 0.10; 95% CI, 0.03 to 0.28). Each trend showed a dose-dependent pattern (p for trend fat at follow-up and a greater increase in visceral fat reduced the regression of erosive esophagitis in a dose-dependent manner.

  9. Assessing and monitoring the risk of desertification in Dobrogea, Romania, using Landsat data and decision tree classifier.

    Science.gov (United States)

    Vorovencii, Iosif

    2015-04-01

    The risk of the desertification of a part of Romania is increasingly evident, constituting a serious problem for the environment and the society. This article attempts to assess and monitor the risk of desertification in Dobrogea using Landsat Thematic Mapper (TM) satellite images acquired in 1987, 1994, 2000, 2007 and 2011. In order to assess the risk of desertification, we used as indicators the Modified Soil Adjustment Vegetation Index 1 (MSAVI1), the Moving Standard Deviation Index (MSDI) and the albedo, indices relating to the vegetation conditions, the landscape pattern and micrometeorology. The decision tree classifier (DTC) was also used on the basis of pre-established rules, and maps displaying six grades of desertification risk were obtained: non, very low, low, medium, high and severe. Land surface temperature (LST) was also used for the analysis. The results indicate that, according to pre-established rules for the period of 1987-2011, there are two grades of desertification risk that have an ascending trend in Dobrogea, namely very low and medium desertification. An investigation into the causes of the desertification risk revealed that high temperature is the main factor, accompanied by the destruction of forest shelterbelts and of the irrigation system and, to a smaller extent, by the fragmentation of agricultural land and the deforestation in the study area.

  10. Body mass index and risk of colorectal carcinoma subtypes classified by tumor differentiation status.

    Science.gov (United States)

    Hanyuda, Akiko; Cao, Yin; Hamada, Tsuyoshi; Nowak, Jonathan A; Qian, Zhi Rong; Masugi, Yohei; da Silva, Annacarolina; Liu, Li; Kosumi, Keisuke; Soong, Thing Rinda; Jhun, Iny; Wu, Kana; Zhang, Xuehong; Song, Mingyang; Meyerhardt, Jeffrey A; Chan, Andrew T; Fuchs, Charles S; Giovannucci, Edward L; Ogino, Shuji; Nishihara, Reiko

    2017-05-01

    Previous studies suggest that abnormal energy balance status may dysregulate intestinal epithelial homeostasis and promote colorectal carcinogenesis, yet little is known about how host energy balance and obesity influence enterocyte differentiation during carcinogenesis. We hypothesized that the association between high body mass index (BMI) and colorectal carcinoma incidence might differ according to tumor histopathologic differentiation status. Using databases of the Nurses' Health Study and Health Professionals Follow-up Study, and duplication-method Cox proportional hazards models, we prospectively examined an association between BMI and the incidence of colorectal carcinoma subtypes classified by differentiation features. 120,813 participants were followed for 26 or 32 years and 1528 rectal and colon cancer cases with available tumor pathological data were documented. The association between BMI and colorectal cancer risk significantly differed depending on the presence or absence of poorly-differentiated foci (P heterogeneity  = 0.006). Higher BMI was associated with a higher risk of colorectal carcinoma without poorly-differentiated foci (≥30.0 vs. 18.5-22.4 kg/m 2 : multivariable-adjusted hazard ratio, 1.87; 95% confidence interval, 1.49-2.34; P trend   0.03, with the adjusted α of 0.01). High BMI was associated with risk of colorectal cancer subtype containing no poorly-differentiated focus. Our findings suggest that carcinogenic influence of excess energy balance might be stronger for tumors that retain better intestinal differentiation throughout the tumor areas.

  11. Seasonality of soil erosion under mediterranean conditions at the Alqueva Dam watershed.

    Science.gov (United States)

    Ferreira, Vera; Panagopoulos, Thomas

    2014-07-01

    The Alqueva reservoir created the largest artificial lake of Western Europe in 2010. Since then, the region has faced challenges due to land-use changes that may increase the risk of erosion and shorten the lifetime of the reservoir, increasing the need to promote land management sustainability. This paper investigates the aspect of seasonality of soil erosion using a comprehensive methodology that integrates the Revised Universal Soil Loss Equation (RUSLE) approach, geographic information systems, geostatistics, and remote-sensing. An experimental agro-silvo pastoral area (typical land-use) was used for the RUSLE factors update. The study confirmed the effect of seasonality on soil erosion rates under Mediterranean conditions. The highest rainfall erosivity values occurred during the autumn season (433.6 MJ mm ha(-1) h(-1)), when vegetation cover is reduced after the long dry season. As a result, the autumn season showed the highest predicted erosion (9.9 t ha(-1)), contributing 65 % of the total annual erosion. The predicted soil erosion for winter was low (1.1 t ha(-1)) despite the high rainfall erosivity during that season (196.6 MJ mm ha(-1) h(-1)). The predicted annual soil loss was 15.1 t ha(-1), and the sediment amount delivery was 4,314 × 10(3) kg. Knowledge of seasonal variation would be essential to outline sustainable land management practices. This model will be integrated with World Overview of Conservation Approaches and Technologies methods to support decision-making in that watershed, and it will involve collaboration with both local people and governmental institutions.

  12. Divertor erosion in DIII-D

    International Nuclear Information System (INIS)

    Whyte, D.G.; Bastasz, R.; Wampler, W.R.; Brooks, J.N.; West, W.P.; Wong, C.P.C.

    1998-05-01

    Net erosion rates of carbon target plates have been measured in situ for the DIII-D lower divertor. The principal method of obtaining this data is the DiMES sample probe. Recent experiments have focused on erosion at the outer strike-point of two divertor plasma conditions: (1) attached (Te > 40 eV) ELMing plasmas and (2) detached (Te 10 cm/year, even with incident heat flux 2 . In this case, measurements and modeling agree for both gross and net carbon erosion, showing the near-surface transport and redeposition of the carbon is well understood and that effective sputtering yields are > 10%. In ELM-free discharges, this erosion rate can account for the rate of carbon accumulation in the core plasma. Divertor plasma detachment eliminates physical sputtering, while spectroscopically measured chemical erosion yields are also found to be low (Y(C/D + ) ≤ 2.0 x 10 -3 ). This leads to suppression of net erosion at the outer strike-point, which becomes a region of net redeposition (∼ 4 cm/year). The private flux wall is measured to be a region of net redeposition with dense, high neutral pressure, attached divertor plasmas. Leading edges intercepting parallel heat flux (∼ 50 MW/m 2 ) have very high net erosion rates (∼ 10 microm/s) at the OSP of an attached plasma. Leading edge erosion, and subsequent carbon redeposition, caused by tile gaps can account for half of the deuterium codeposition in the DIII-D divertor

  13. Molybdenum erosion measurements in Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    Wampler, W.R. [Sandia National Labs., Albuquerque, NM (United States); LaBombard, B.; Lipshultz, B.; Pappas, D.; Pitcher, C.S. [Massachusetts Inst. of Tech., Cambridge, MA (United States); McCracken, G.M. [JET Joint Undertaking, Abingdon (United Kingdom)

    1998-05-01

    Erosion of molybdenum was measured on a set of 21 tiles after a run campaign of 1,090 shots in the Alcator C-Mod tokamak. The net erosion of molybdenum, was determined from changes in the depth of a thin chromium marker layer measured by Rutherford backscattering. Net Mo erosion was found to be approximately 150 nm near the outer divertor strike point, and much less everywhere else. Gross erosion rates by sputtering were estimated using ion energies and fluxes obtained from Langmuir probe measurements of edge-plasma conditions. Predicted net erosion using calculated gross erosion with prompt redeposition and measured net erosion agree within a factor of 3. Sputtering by boron and molybdenum impurities dominates erosion.

  14. The Monitoring Erosion of Agricultural Land and spatial database of erosion events

    Science.gov (United States)

    Kapicka, Jiri; Zizala, Daniel

    2013-04-01

    In 2011 originated in The Czech Republic The Monitoring Erosion of Agricultural Land as joint project of State Land Office (SLO) and Research Institute for Soil and Water Conservation (RISWC). The aim of the project is collecting and record keeping information about erosion events on agricultural land and their evaluation. The main idea is a creation of a spatial database that will be source of data and information for evaluation and modeling erosion process, for proposal of preventive measures and measures to reduce negative impacts of erosion events. A subject of monitoring is the manifestations of water erosion, wind erosion and slope deformation in which cause damaged agriculture land. A website, available on http://me.vumop.cz, is used as a tool for keeping and browsing information about monitored events. SLO employees carry out record keeping. RISWC is specialist institute in the Monitoring Erosion of Agricultural Land that performs keeping the spatial database, running the website, managing the record keeping of events, analysis the cause of origins events and statistical evaluations of keeping events and proposed measures. Records are inserted into the database using the user interface of the website which has map server as a component. Website is based on database technology PostgreSQL with superstructure PostGIS and MapServer UMN. Each record is in the database spatial localized by a drawing and it contains description information about character of event (data, situation description etc.) then there are recorded information about land cover and about grown crops. A part of database is photodocumentation which is taken in field reconnaissance which is performed within two days after notify of event. Another part of database are information about precipitations from accessible precipitation gauges. Website allows to do simple spatial analysis as are area calculation, slope calculation, percentage representation of GAEC etc.. Database structure was designed

  15. Use of 7Be to document soil erosion associated with a short period of extreme rainfall

    International Nuclear Information System (INIS)

    Sepulveda, A.; Schuller, P.; Walling, D.E.; Castillo, A.

    2008-01-01

    Intensification and expansion of agricultural production since the 1970s have increased soil erosion problems in south-central Chile. Quantitative information on soil loss is needed for erosion risk assessment and to establish the effectiveness of improved land management practices. Since information from traditional sources, such as erosion plots, is limited, attention has been directed to the use of environmental radionuclides for documenting erosion rates. Cs-137 has been successfully utilised for this purpose, but only provides information on medium-term erosion rates. There is also a need to document event-related soil erosion. This paper outlines the basis for using 7 Be measurements to document short-term erosion and reports its successful use for quantifying the erosion that occurred within an arable field, as a result of a period of heavy rainfall (400 mm in 27 days) occurring in May 2005. The study field had been under a no-till, no-burning system for 18 years, but immediately prior to the period of heavy rainfall the harvest residues were burnt. The erosion recorded therefore reflected both the extreme nature of the rainfall and the effects of the burning in increasing surface runoff and erosion. The sampled area corresponded to that used previously by the authors to document the medium-term erosion rates associated with both conventional tillage and the subsequent switch to a no-till system. Comparisons between the erosion documented for the period of heavy rainfall in 2005 with these medium-term erosion rates permits some tentative conclusions regarding the importance of extreme events and the impact of burning in increasing the erosion associated with the no-till system

  16. Gastric Mucosal Erosions - Radiologic evaluation -

    International Nuclear Information System (INIS)

    Kim, Seung Hyup

    1985-01-01

    70 cases of gastric mucosal erosions were diagnosed by double contrast upper gastrointestinal examinations and endoscopic findings. Analyzing the radiologic findings of these 70 cases of gastric mucosal erosions, the following results were obtained. 1. Among the total 70 cases, 65 cases were typical varioliform erosions showing central depressions and surrounding mucosal elevations. Remaining 5 cases were erosions of acute phase having multiple irregular depressions without surrounding elevations. 2. The gastric antrum was involved alone or in part in all cases. Duodenal bulb was involved with gastric antrum in 4 cases. 3. The majority of the cases had multiple erosions. There were only 2 cases of single erosion. 4. In 65 cases of varioliform erosions; 1) The diameter of the surrounding elevations varied from 3 to 20 mm with the majority (47 cases) between 6 and 10 mm. 2) In general, the surrounding elevations with sharp margin on double contrast films were also clearly demonstrated on compression films but those with faint margin were not. 3) The size of the central barium collections varied from pinpoint to 10 mm with the majority under 5 mm. The shape of the central barium collections in majority of the cases were round with a few cases of linear, triangular or star-shape. 5. In 5 cases of acute phase erosions; 1) All the 5 cases were females. 2) On double contrast radiography, all the cases showed multiple irregular depressed lesions without surrounding elevations. 3) 1 case had the history of hematemesis. 4) In 1 case, there was marked radiological improvement on follow-up study of 2 months interval. 6. In 23 cases, there were coexistent diseases with gastric mucosal erosions. These were 13 cases of duodenal bulb ulcers,7 cases of benign gastric ulcers and 3 others

  17. Classified facilities for environmental protection

    International Nuclear Information System (INIS)

    Anon.

    1993-02-01

    The legislation of the classified facilities governs most of the dangerous or polluting industries or fixed activities. It rests on the law of 9 July 1976 concerning facilities classified for environmental protection and its application decree of 21 September 1977. This legislation, the general texts of which appear in this volume 1, aims to prevent all the risks and the harmful effects coming from an installation (air, water or soil pollutions, wastes, even aesthetic breaches). The polluting or dangerous activities are defined in a list called nomenclature which subjects the facilities to a declaration or an authorization procedure. The authorization is delivered by the prefect at the end of an open and contradictory procedure after a public survey. In addition, the facilities can be subjected to technical regulations fixed by the Environment Minister (volume 2) or by the prefect for facilities subjected to declaration (volume 3). (A.B.)

  18. Land degradation due to erosion in public perception. Case study: Secaşul Mare river basin settlements (Transylvanian Depression, Romania).

    Science.gov (United States)

    Costea, Marioara; Tăuşan, Ioan

    2016-04-01

    According to the International Decade for Natural Disaster Reduction (IDNDR 1990-1999), the risk indicates potential losses due to particular natural phenomenon, and these could be reduced by improving of prevention and education. People perceive these losses differently depending on phenomenon occurrence, severity, and impact in time. Starting from this idea, this research presents public perception on land degradation through erosion in a small area from the central part of Romania (south-west of Transylvanian Depression). The research was based on a questionnaire consisting of 16 questions. The items were structured by issues: awareness assessment regarding hazard and risk phenomena, assessment of type of property and land use, assessment of knowledge and information on the possible production of negative effects by natural phenomena, and evaluation of land owners' attitudes towards the occurrence of erosion on their land. Results reveal that the public perception on erosion is weak. This process is perceived as insignificant due to lack of phenomenon knowledge and especially because of scarcity preoccupation in land's quality monitoring. Even though the owned lands are affected by erosion forms, the owners are not aware of the phenomenon that generates them. Material damages caused by erosion, loss of soil quality, and land fertility decrease are less perceived because the economic losses fill only at long term. This perception leads to underestimating erosion risk compared to other natural phenomena and to a passive attitude towards this particular phenomenon.

  19. Coastal Erosion Control Methods

    Science.gov (United States)

    Greene, V.

    2016-12-01

    Coastal erosion is bad because the ecosystem there will be washed away and the animals could drown or be displaced and have to adapt to a new ecosystem that they are not prepared for. I'm interested in this problem because if there aren't beaches when I grow up I won't be able to do the things I would really like to do. I would like to be a marine biologist. Secondly, I don't want to see beach houses washed away. I would like to see people live in harmony with their environment. So, to study ways in which to preserve beaches I will make and use models that test different erosion controls. Two different ideas for erosion control I tested are using seaweed or a rock berm. I think the rock berm will work better than the model of seaweed because the seaweed is under water and the waves can carry the sand over the seaweed, and the rock berm will work better because the rocks will help break the waves up before they reach the shore and the waves can not carry the sand over the rocks that are above the water. To investigate this I got a container to use to model the Gulf of Mexico coastline. I performed several test runs using sand and water in the container to mimic the beach and waves from the Gulf of Mexico hitting the shoreline. I did three trials for the control (no erosion control), seaweed and a rock berm. Rock berms are a border of a raised area of rock. The model for seaweed that I used was plastic shopping bags cut into strips and glued to the bottom of my container to mimic seaweed. My results were that the control had the most erosion which ranged from 2.75 - 3 inches over 3 trials. The seaweed was a little better than the control but was very variable and ranged from 1.5 - 3 inches over 3 trials. The rock berm worked the best out of all at controlling erosion with erosion ranging from 1.5 - 2 inches. My hypothesis was correct because the rock berm did best to control erosion compared to the control which had no erosion control and the model with seaweed.

  20. Geo-statistical model of Rainfall erosivity by using high temporal resolution precipitation data in Europe

    Science.gov (United States)

    Panagos, Panos; Ballabio, Cristiano; Borrelli, Pasquale; Meusburger, Katrin; Alewell, Christine

    2015-04-01

    Rainfall erosivity (R-factor) is among the 6 input factors in estimating soil erosion risk by using the empirical Revised Universal Soil Loss Equation (RUSLE). R-factor is a driving force for soil erosion modelling and potentially can be used in flood risk assessments, landslides susceptibility, post-fire damage assessment, application of agricultural management practices and climate change modelling. The rainfall erosivity is extremely difficult to model at large scale (national, European) due to lack of high temporal resolution precipitation data which cover long-time series. In most cases, R-factor is estimated based on empirical equations which take into account precipitation volume. The Rainfall Erosivity Database on the European Scale (REDES) is the output of an extensive data collection of high resolution precipitation data in the 28 Member States of the European Union plus Switzerland taking place during 2013-2014 in collaboration with national meteorological/environmental services. Due to different temporal resolutions of the data (5, 10, 15, 30, 60 minutes), conversion equations have been applied in order to homogenise the database at 30-minutes interval. The 1,541 stations included in REDES have been interpolated using the Gaussian Process Regression (GPR) model using as covariates the climatic data (monthly precipitation, monthly temperature, wettest/driest month) from WorldClim Database, Digital Elevation Model and latitude/longitude. GPR has been selected among other candidate models (GAM, Regression Kriging) due the best performance both in cross validation (R2=0.63) and in fitting dataset (R2=0.72). The highest uncertainty has been noticed in North-western Scotland, North Sweden and Finland due to limited number of stations in REDES. Also, in highlands such as Alpine arch and Pyrenees the diversity of environmental features forced relatively high uncertainty. The rainfall erosivity map of Europe available at 500m resolution plus the standard error

  1. Caries and dental erosion: are Soroti children and adolescents at risk from increased soft-drink availability in Uganda?

    Science.gov (United States)

    Cheng, Jordan; Campbell, Karen

    2016-12-01

    An initial field study to investigate dental caries and dental erosion in children and adolescents in the community of Soroti, Uganda. A stratified two-stage cluster sample of 84 children (ages 8-10) and adolescents (ages 16-19) were recruited. A survey was undertaken to assess the state of determinants of oral health, oral hygiene practices, and soft-drink and sweetened-tea consumption. Intra-oral photographs were taken and reviewed to measure Decayed, Missing, and Filled Teeth (DMFT) and dental erosion. A significant difference was observed in DMFT between children and adolescents (3.7 ± 2.7 versus 2.1 ± 2.4 p=.02). A trend of lower erosion scores was seen in children compared to adolescents. Greater frequency of sweetened-tea consumption over soft-drinks was noted in both groups. This study did not reveal any relationship between different levels of cariogenic beverage consumption and DMFT or dental erosion in this sample group.

  2. Classifying Microorganisms

    DEFF Research Database (Denmark)

    Sommerlund, Julie

    2006-01-01

    This paper describes the coexistence of two systems for classifying organisms and species: a dominant genetic system and an older naturalist system. The former classifies species and traces their evolution on the basis of genetic characteristics, while the latter employs physiological characteris......This paper describes the coexistence of two systems for classifying organisms and species: a dominant genetic system and an older naturalist system. The former classifies species and traces their evolution on the basis of genetic characteristics, while the latter employs physiological...... characteristics. The coexistence of the classification systems does not lead to a conflict between them. Rather, the systems seem to co-exist in different configurations, through which they are complementary, contradictory and inclusive in different situations-sometimes simultaneously. The systems come...

  3. Deforestation Effects on Soil Erosion in the Lake Kivu Basin, D.R. Congo-Rwanda

    Directory of Open Access Journals (Sweden)

    Fidele Karamage

    2016-11-01

    Full Text Available Deforestation and natural grassland conversion to agricultural land use constitute a major threat to soil and water conservation. This study aimed at assessing the status of land cover and land use (LCLU in the Lake Kivu basin, and its related impacts in terms of soil erosion by water using the Universal Soil Erosion Equation (USLE model. The results indicated that the Lake Kivu basin is exposed to soil erosion risk with a mean annual rate of 30 t·ha−1, and only 33% of the total non-water area is associated with a tolerable soil loss (≤10 t·ha−1·year−1. Due to both natural factors (abundant tropical precipitation and steep slopes and anthropogenic activities without prior appropriate conservation practices, all land-use types—namely settlement, cropland, forestland, and grassland—are exposed to a severe mean erosion rate of 41 t·ha−1·year−1, 31 t·ha−1·year−1, 28 t·ha−1·year−1, and 20 t·ha−1·year−1, respectively. The cropland that occupied 74% of the non-water area in 2015 was the major contributor (75% to the total annual soil loss in the Lake Kivu basin. This study showed that conservation practices in the cropland cells would result in a mean erosion rate of 7 t·ha−1·year−1, 18 t·ha−1·year−1, and 35 t·ha−1·year−1 for terracing, strip-cropping, and contouring, respectively. The adoption of terracing would be the best conservation practice, among others, that could reduce soil erosion in cropland areas up to about 23%. The erosion risk minimization in forests and grasslands implies an increase in overstorey canopy and understorey vegetation, and control of human activities such as fires, mining, soil compaction from domestic animals grazing, and so on. Soil erosion control in settled areas suggests, among other things, the revegetation of construction sites, establishment of outlet channels, rainfall water harvesting systems, and pervious paving block with grass.

  4. A New European Slope Length and Steepness Factor (LS-Factor for Modeling Soil Erosion by Water

    Directory of Open Access Journals (Sweden)

    Panos Panagos

    2015-04-01

    Full Text Available The Universal Soil Loss Equation (USLE model is the most frequently used model for soil erosion risk estimation. Among the six input layers, the combined slope length and slope angle (LS-factor has the greatest influence on soil loss at the European scale. The S-factor measures the effect of slope steepness, and the L-factor defines the impact of slope length. The combined LS-factor describes the effect of topography on soil erosion. The European Soil Data Centre (ESDAC developed a new pan-European high-resolution soil erosion assessment to achieve a better understanding of the spatial and temporal patterns of soil erosion in Europe. The LS-calculation was performed using the original equation proposed by Desmet and Govers (1996 and implemented using the System for Automated Geoscientific Analyses (SAGA, which incorporates a multiple flow algorithm and contributes to a precise estimation of flow accumulation. The LS-factor dataset was calculated using a high-resolution (25 m Digital Elevation Model (DEM for the whole European Union, resulting in an improved delineation of areas at risk of soil erosion as compared to lower-resolution datasets. This combined approach of using GIS software tools with high-resolution DEMs has been successfully applied in regional assessments in the past, and is now being applied for first time at the European scale.

  5. Divertor erosion in DIII-D

    International Nuclear Information System (INIS)

    Whyte, D.G.; Bastasz, R.; Wampler, W.R.; Brooks, J.N.; West, W.P.; Wong, C.P.C.; Buzhinskij, O.I.; Opimach, I.V.

    1998-08-01

    Net erosion rates of carbon target plates have been measured in situ for the DIII-D lower divertor. The principal method of obtaining this data is the DiMES sample probe. Recent experiments have focused on erosion at the outer strike-point (OSP) of two divertor plasma conditions: attached (T e > 40 eV) ELMing plasmas, and detached (T e 2 . In this case, measurements and modeling agree for both gross and net carbon erosion, showing the near-surface transport and redeposition of the carbon is well understood. In the attached cases, physical sputtering (with enhancement from self-sputtering and oblique incidence) is dominant, and the effective sputtering yield, Y, is greater than 10%. In ELM-free discharges, the total OSP net erosion rate is equal to the rate of carbon accumulation in the core plasma. For the detached divertor cases, the cold incident plasma eliminates physical sputtering. Attempts to measure chemically eroded hydrocarbon molecules spectroscopically indicate an upper limit of Y ≤ 0.1% for the chemical sputtering yield. Net erosion is suppressed at the outer strike-point, which becomes a region of net redeposition (∼ 4 cm/exposure-year). The private flux wall is measured to be a region of net redeposition with dense, high neutral pressure, attached divertor plasmas. Leading edges intercepting parallel heat flux (∼ 50 MW/m 2 ) have very high net erosion rates at the OSP of an attached plasma (∼ 10 microm/s > 1,000x erosion rate of aligned surfaces). Leading edge erosion, and subsequent carbon redeposition, caused by tile gaps can account for half of the deuterium codeposition in the DIII-D divertor

  6. Design of Robust Neural Network Classifiers

    DEFF Research Database (Denmark)

    Larsen, Jan; Andersen, Lars Nonboe; Hintz-Madsen, Mads

    1998-01-01

    This paper addresses a new framework for designing robust neural network classifiers. The network is optimized using the maximum a posteriori technique, i.e., the cost function is the sum of the log-likelihood and a regularization term (prior). In order to perform robust classification, we present...... a modified likelihood function which incorporates the potential risk of outliers in the data. This leads to the introduction of a new parameter, the outlier probability. Designing the neural classifier involves optimization of network weights as well as outlier probability and regularization parameters. We...... suggest to adapt the outlier probability and regularisation parameters by minimizing the error on a validation set, and a simple gradient descent scheme is derived. In addition, the framework allows for constructing a simple outlier detector. Experiments with artificial data demonstrate the potential...

  7. X-ray diagnosis of erosive gastritis

    International Nuclear Information System (INIS)

    Taskov, A.; Krastin, A.

    1993-01-01

    A series of 602 patients are studied according to a standard protocol including double contrast examination, taking films with dosed compression and complete filling (accordingly 3+3+1 radiographs). A barium suspension at concentration 200.0 BaSO 4 in 100 ml water is used as a positive contrast medium, and effervescent powder or pills - as a negative contrast. Erosive gastritis is diagnosed in 48 patients (7.9%) of which 38 present complete erosions (79.2%), 6 (12.6%) - incomplete, and 4 (8.3%) - mixed erosions. In 35 cases (72.9%) erosions are differentiated in double-contrast films, while in 21 (43.8%) - in those with compression. The advantage of the double contrast technique consists in visualization of erosions of the body of the stomach and discovering of incomplete erosions. In 483 patients a comparative assessment is done of the X-ray and endoscopic findings. There are recorded 5 false-positive and 25 false-negative radiological results. The sensitivity of the X-ray study in terms of erosive gastritis amounts to 59.7%. 15 refs., 4 figs. (orig.)

  8. STUDY ON IMPACT OF SALINE WATER INUNDATION ON FRESHWATER AQUACULTURE IN SUNDARBAN USING RISK ANALYSIS TOOLS

    Directory of Open Access Journals (Sweden)

    B.K Chand

    2012-11-01

    Full Text Available The impact of saline water inundation on freshwater aquaculture was evaluated through risk assessment tools. Fishponds in low-lying areas of Sagar and Basanti block are prone to saline water flooding. Respondents of Sagar block considered events like cyclone and coastal flooding as extreme risk; erratic monsoon, storm surge and land erosion as high risk; temperature rise, sea level rise, hot & extended summer and precipitation as medium risk. Likewise, in Basanti block the respondents rated cyclone as extreme risk; erratic monsoon, storm surge as high risk; temperature rise, hot & extended summer, land erosion, and precipitation as medium risk; coastal flooding and sea level rise as low risk. Fish farmers of Sagar block classified the consequences of saline water flooding like breach of pond embankment and mass mortality of fishes as extreme risk; escape of existing fish stock and diseases as high risk; entry of unwanted species, retardation of growth and deterioration of water quality as medium risk; and damage of pond environment as low risk. Farmers of Basanti block categorised breach of pond dyke, mass mortality of fishes and entry of unwanted species as extreme risk; escape of fish and diseases as high risk; retardation of growth as medium risk; deterioration of water quality and damage of pond environment as low risk. To reduce the threats against saline water ingression, farmers are taking some coping measures like increase in pond dyke height; repair and strengthening of dyke; plantation on dyke; dewatering and addition of fresh water; application of chemicals/ lime/ dung; addition of tree branches in pond for hide outs etc.

  9. Mapping monthly rainfall erosivity in Europe

    DEFF Research Database (Denmark)

    Ballabio, C; Meusburger, K; Klik, A

    2017-01-01

    to Eastern Europe. The maps also show a clear delineation of areas with different erosivity seasonal patterns, whose spatial outline was evidenced by cluster analysis. The monthly erosivity maps can be used to develop composite indicators that map both intra-annual variability and concentration of erosive...... and seasonal R-factor maps and assess rainfall erosivity both spatially and temporally. During winter months, significant rainfall erosivity is present only in part of the Mediterranean countries. A sudden increase of erosivity occurs in major part of European Union (except Mediterranean basin, western part...... selected among various statistical models to perform the spatial interpolation due to its excellent performance, ability to model non-linearity and interpretability. The monthly prediction is an order more difficult than the annual one as it is limited by the number of covariates and, for consistency...

  10. Runoff and soil erosion for an undisturbed tropical woodland in the Brazilian Cerrado

    Science.gov (United States)

    Oliveira, Paulo Tarso S.; Nearing, Mark; Wendland, Edson

    2015-04-01

    The Brazilian Cerrado is a large and important economic and environmental region that is experiencing major loss of its natural landscapes due to pressures of food and energy production, which has caused large increases in soil erosion. However the magnitude of the soil erosion increases in this region is not well understood, in part because scientific studies of surface runoff and soil erosion are scarce or nonexistent in undisturbed Cerrado vegetation. In this study we measured natural rainfall-driven rates of runoff and soil erosion for an undisturbed tropical woodland classified as "cerrado sensu stricto denso" and bare soil to compute the Universal Soil Loss Equation (USLE) cover and management factor (C-factor) to help evaluate the likely effects of land use change on soil erosion rates. Replicated data on precipitation, runoff, and soil loss on plots (5 x 20 m) under bare soil and cerrado were collected for 55 erosive storms occurring in 2012 and 2013. The measured annual precipitation was 1247.4 mm and 1113.0 mm for 2012 and 2013, resulting in a rainfall erosivity index of 4337.1 MJ mm ha-1 h-1 and 3546.2 MJ mm ha-1 h-1, for each year respectively. The erosive rainfall represented 80concentrated in the wet season, which generally runs from October through March. In the plots on bare soil, the runoff coefficient for individual rainfall events (total runoff divided by total rainfall) ranged from 0.003 to 0.860 with an average value and standard deviation of 0.212 ± 0.187. Moreover, the runoff coefficient found for the bare soil plots (~20infiltration capacity. In forest areas the leaf litter and the more porous soil tend to promote the increase of infiltration and water storage, rather than rapid overland flow. Indeed, runoff coefficients ranged from 0.001 to 0.030 with an average of less than 1under undisturbed cerrado. The soil losses measured under bare soil and cerrado were 15.68 t ha-1yr-1 and 0.24 t ha-1 yr-1 in 2012, and 14.82 t ha-1 yr-1, 0.11 t ha-1

  11. Dental caries and erosion status of 12-year-old Hong Kong children.

    Science.gov (United States)

    Zhang, Shinan; Chau, Alex Mh; Lo, Edward Cm; Chu, Chun-Hung

    2014-01-08

    This study aimed to assess the dental caries and erosion status of 12-year-old Hong Kong children and study the determinants of dental caries and dental erosion of these children. The survey was performed from 2011 to 2012 with ethics approval. Stratified random sampling was adopted to select 12-year-old children in 7 primary schools in Hong Kong. The participating parents were asked to complete a self-administered questionnaire concerning their children's diet and oral health habits. The children were examined for caries status with WHO criteria by 3 calibrated examiners. Detection of dental erosion followed Basic Erosive Wear Examination (BEWE) criteria. A total of 704 children were recruited and 600 (316 boys, 53%) participated in the survey. There were 124 children (21%) with caries experience (DMFT > 0) and their DMFT was 0.34 ± 0.76. About half of their decay was unfilled (DT = 0.16 ± 0.52) The DMFT of girls and boys were 0.45 ± 0.89 and 0.23 ± 0.61, respectively (p = 0.001). Girls also had a higher DT (0.21 ± 0.62 compared with 0.11 ± 0.41, p = 0.013) and FT than boys (0.23 ± 0.63 compared with 0.12 ± 0.44, p = 0.016). Most children (75%) had at least some sign of erosion (BEWE > 0), but no severe erosion (BEWE = 3). Logistic regression showed girls who consumed soft drinks and took vitamin C supplements had higher caries risk. Dental erosion was more severe among the children who had caries experience and consumed fruit juice. The 12-year-old Hong Kong children had low caries experience, and almost half of the decay was left untreated. Although severe erosion was not found, many children had early signs of erosion.

  12. Spatial and temporal variations of wind erosion climatic erosivity in the farming-pastoral zone of Northern China

    Science.gov (United States)

    Yue, Shuping; Yang, Ruixin; Yan, Yechao; Yang, Zhengwei; Wang, Dandan

    2018-03-01

    Wind erosion climatic erosivity is an important parameter to assess the possible effects of climatic conditions on wind erosion. In this paper, the wind erosion climatic factor (C-factor), which was used to quantify the wind erosion climatic erosivity, was calculated for the period 1960-2014 based on monthly meteorological data collected from 101 stations in the farming-pastoral zone of Northern China. The Mann-Kendall (M-K) test, trend analysis, and geostatistical analysis methods were used to explore the spatial and temporal characteristics of the wind erosion climatic erosivity in this region. The result suggests that the annual C-factor, with a maximum of 76.05 in 1969 and a minimum of 26.57 in 2007, has a significant decreasing trend over the past 55 years. Strong seasonality in the C-factor was found, with the highest value in spring, which accounts for a significant proportion of the annual C-factor (41.46%). However, the coefficient of variation of the seasonal C-factor reaches a maximum in winter and a minimum in spring. The mean annual C-factor varies substantially across the region. Areas with high values of the mean annual C-factor (C ≥ 100) are located in Ulanqab and Dingxi, while areas with low values (C ≤ 10) lie in Lanzhou, Linxia, Dingxi, Xining, and Chengde. Spatial analysis on the trend of the C-factor reveals that 81% of the stations show statistically significant decreases at a 90% confidence level. An examination of the concentration ratio of the C-factor shows that the wind erosion climatic erosivity is concentrated in spring, especially in April, which makes this period particularly important for implementing soil conservation measures.

  13. On the geoethical implications of wind erosion

    Science.gov (United States)

    Károly, Tatárvári

    2016-04-01

    Human activities exerts an ever growing impact on our environment, and this is undeniably the responsibility of mankind. In spite of this fact there is almost no process in our environment that can be described exactly with complete exactness, and the working of which is known in full extent. Wind erosion is such a process. Although water erosion is mentioned ever more often in scientific circles as a from of erosion, its effect is restrained to a certain region, although it may cause perceptibly damage of a greater extent in short time. Wind erosion, apart from the fact that it may have global impact, may play an important role in the warming of our climate according to recent studies. First of all, wind erosion may cause damage far from its origin in human health, nutrition, or in the environment in general. Today several surveys have proved, that erosion caused by wind significantly contributes to the air pollution of cities, the fine dust carried as drift by the wind may cause severe environmental damage in accumulation zones. Microbes, toxic material may attach themselves to the dust carried this way and carried on and by the wings of the wind they may cause health issues in humans animals and plants as well. In spite of these facts there are almost no measures against wind erosion employed in arable land, although our ever doughtier climate and changes would make these necessary. Reduction of organic matter content presents a great problem in a large part of cultivated land, so the risk of the production of high quality food raises questions of more and more ethical nature. Who is responsible? The fact, that the chemicals used in a growing extent by agriculture may reach many people causing considerable damage to the environment also raises serious ethical questions. More and more periods with extreme weather conditions are experienced in Hungary and Europe as the effect of climate change. Drought periods are longer and more frequent as the intensity of

  14. Elevated temperature erosive wear of metallic materials

    International Nuclear Information System (INIS)

    Roy, Manish

    2006-01-01

    Solid particle erosion of metals and alloys at elevated temperature is governed by the nature of the interaction between erosion and oxidation, which, in turn, is determined by the thickness, pliability, morphology, adhesion characteristics and toughness of the oxide scale. The main objective of this paper is to critically review the present state of understanding of the elevated temperature erosion behaviour of metals and alloys. First of all, the erosion testing at elevated temperature is reviewed. This is followed by discussion of the essential features of elevated temperature erosion with special emphasis on microscopic observation, giving details of the erosion-oxidation (E-O) interaction mechanisms. The E-O interaction has been elaborated in the subsequent section. The E-O interaction includes E-O maps, analysis of transition criteria from one erosion mechanism to another mechanism and quantification of enhanced oxidation kinetics during erosion. Finally, the relevant areas for future studies are indicated. (topical review)

  15. Soil erosion processes on sloping land using REE tracer

    International Nuclear Information System (INIS)

    Shen Zhenzhou; Liu Puling; Yang Mingyi; Lian Zhenlong; Ju Tongjun; Yao Wenyi; Li Mian

    2007-01-01

    Sheet erosion is the main performance in the slope soil erosion process at the primary stage of natural rainfall. For three times of rainfall during experiment, the ratios of sheet erosion to total erosion account for 71%, 48% and 49% respectively, which showed that the sloping erosion was still at the primary stage from sheet erosion to rill erosion. With the rainfall going, the rill erosion amount increase. It showed that soil erosion was changing from sheet erosion to rill erosion. The sources of sediment from different sections of the plot were analyzed, and the results indicated that whatever the sheet erosion changed, the ratio erosion of upper part of surface soil was always lower than 10%. Sheet erosion came mainly from the lower section of surface soil. With the ratios to the amount of total rill erosion changes, the rill erosion amount of each section regularly changes too. The general conclusion is that when the rainfall ends, relative erosion of different slope element to the foot of slope is: 1 meter away accounts for 16%, 2-4 meters away is 6% and 5-9 meters away is 3%. The ratio of rill erosion amount of these three slope element is 5:2:1, which shows the rill erosion amount are mainly from the slope element of 4 meters from the foot of slope. (authors)

  16. The method of determining surface water erosion influence on agricultural valorization of soils with usage of geoprocessing techniques and spatial information systems

    Directory of Open Access Journals (Sweden)

    Prus Barbara

    2016-12-01

    Full Text Available The aim of the paper is to propose methodical solutions concerning synthetic agricultural analysis of production space which consists in combined (synthetic – in spatial and statistical contexts – analysis and evaluation of quality and farming utility of soils in connection with soils erosive risk level. The paper is aimed at presentation of methodology useful in such type of analyses as well as demonstration to what extent the areas of farming production space being subject to restrictive protection are exposed to destructive effect of surface water erosion. Own factor (HDSP.E was suggested, which is a high degree synthesis of soil protection in connection with degrees of surface water erosion risk. The proposed methodology was used for detailed spatial analyses performed for Tomice – the Małopolska rural commune (case study. The area model elaborated for the proposed methodology’s purpose faced with soils mechanical composition allowed to make a model of surface water erosion in five-grade scale. Synthetic evaluation (product of spatial objects on numerous thematic layers of quality and farming utility of soils and also zones of surface water erosion risk allowed to assign spatial distribution of HDSP.E factor (abbreviation of high degree of soil protection combined with erosion. The analyses enabled to determine proportional contribution of the most valuable resources of farming production space that are subject to soil erosion negative phenomenon. Geoprocessing techniques used for the analyses of environmental elements of farming production space were applied in the paper. The analysis of spatial distribution of researched phenomena was elaborated in Quantum GIS programme.

  17. Soil Erosion and Agricultural Sustainability

    Science.gov (United States)

    Montgomery, D. R.

    2009-04-01

    Data drawn from a global compilation of studies support the long articulated contention that erosion rates from conventionally plowed agricultural fields greatly exceed rates of soil production, erosion under native vegetation, and long-term geological erosion. Whereas data compiled from around the world show that soil erosion under conventional agriculture exceeds both rates of soil production and geological erosion rates by up to several orders of magnitude, similar global distributions of soil production and geological erosion rates suggest an approximate balance. Net soil erosion rates in conventionally plowed fields on the order of 1 mm/yr can erode typical hillslope soil profiles over centuries to millennia, time-scales comparable to the longevity of major civilizations. Well-documented episodes of soil loss associated with agricultural activities date back to the introduction of erosive agricultural methods in regions around the world, and stratigraphic records of accelerated anthropogenic soil erosion have been recovered from lake, fluvial, and colluvial stratigraphy, as well as truncation of soil stratigraphy (such as truncated A horizons). A broad convergence in the results from studies based on various approaches employed to study ancient soil loss and rates of downstream sedimentation implies that widespread soil loss has accompanied human agricultural intensification in examples drawn from around the world. While a broad range of factors, including climate variability and society-specific social and economic contexts — such as wars or colonial relationships — all naturally influence the longevity of human societies, the ongoing loss of topsoil inferred from studies of soil erosion rates in conventional agricultural systems has obvious long-term implications for agricultural sustainability. Consequently, modern agriculture — and therefore global society — faces a fundamental question over the upcoming centuries. Can an agricultural system

  18. Medication-related dental erosion: a review.

    Science.gov (United States)

    Thomas, Manuel S; Vivekananda Pai, A R; Yadav, Amit

    2015-10-01

    Dental erosion has become a major problem that affects the long-term health of the dentition. Among the various potential causes for erosive tooth wear, the different drugs prescribed for patients may be overlooked. Several therapeutic medications can directly or indirectly be associated with dental erosion. It is the responsibility of oral health providers to make both patients and colleagues aware of drugs that may contribute to this condition. Therefore, the purpose of this discussion is to provide an overview of the various therapeutic medications that can be related to tooth erosion. The authors also include precautionary measures-summarized as The 9 Rs-to avoid or at least reduce medication-induced erosion.

  19. Experiments and Numerical Simulations of Dike Erosion due to a Wave Impact

    Directory of Open Access Journals (Sweden)

    Stefania Evangelista

    2015-10-01

    Full Text Available Dike erosion is a crucial issue in coastal and fluvial flood risk management. These defense structures appear vulnerable to extreme hydrological events, whose potential occurrence risk seems to be recently increased due to climate change. Their design and reinforcement is, however, a complex task, and although numerical models are very powerful nowadays, real processes cannot be accurately predicted; therefore, physical models constitute a useful tool to investigate different features under controlled conditions. This paper presents some laboratory experimental results of erosion of a sand dike produced by the impact of a dam break wave. Experiments have been conducted in the Water Engineering Laboratory at the University of Cassino and Southern Lazio, Italy, in a rectangular channel: here, the sudden opening of a gate forming the reservoir generates the wave impacting the dike, made in turn of two different, almost uniform sands. The physical evidence proves that the erosion process is strongly unsteady and significantly different from a gradual overtopping and highlights the importance of apparent cohesion for the fine sand dike. The experimental results have also been compared against the ones obtained through the numerical integration of a two-phase model, which shows the reasonable predictive capability of the temporal free surface and dike profile evolution.

  20. Composition of enamel pellicle from dental erosion patients.

    Science.gov (United States)

    Carpenter, G; Cotroneo, E; Moazzez, R; Rojas-Serrano, M; Donaldson, N; Austin, R; Zaidel, L; Bartlett, D; Proctor, G

    2014-01-01

    Oral health is dependent upon a thin mobile film of saliva on soft and hard tissues. Salivary proteins adhere to teeth to form the acquired enamel pellicle which is believed to protect teeth from acid erosion. This study investigated whether patients suffering diet-induced dental erosion had altered enamel pellicles. Thirty patients suffering erosion were compared to healthy age-matched controls. Subjects wore a maxillary splint holding hydroxyapatite and human enamel blocks for 1 h. The acquired enamel pellicle was removed from the blocks and compared to the natural incisor pellicle. Basic Erosive Wear Examination scores confirmed that dental erosion was present in erosion patients and absent from healthy age-matched controls. Erosion patients had half the amount of proteins (BCA assay) within the acquired pellicle forming on splint blocks compared to normal controls (p erosion patients (p erosion patients and healthy controls. In summary, the formation of new acquired pellicles on surfaces was reduced in erosion patients, which may explain their greater susceptibility to acid erosion of teeth. © 2014 S. Karger AG, Basel.

  1. Remote sensing and GIS based study of potential erosion and degradation areas on the island Fogo (Cape Verde Islands)

    Science.gov (United States)

    Olehowski, Claas; Naumann, Simone; Siegmund, Alexander

    2009-09-01

    The Island of Fogo (Cape Verde) is affected by processes of erosion and degradation, caused mainly by a high population growth and global change. With its small scaled climatic, floristic and geo-ecological differentiation, the island of Fogo is an optimal research space for understanding semiarid island ecosystems in the marginal tropics and their behaviour to erosion and degradation processes. For that reason, a change detection analysis over the past two decades is generated, showing the level and direction of land cover and land use change. Two satellite images from 1984 and 2007 will classified by a Maximum Likelihood approach. In a further step, an image of 1974 will be also integrated in this change detection analysis, enlarging the study over the last three decades.

  2. Erosion risk analysis by GIS in environmental impact assessments: a case study--Seyhan Köprü Dam construction.

    Science.gov (United States)

    Sahin, S; Kurum, E

    2002-11-01

    Environmental Impact Assessment (EIA) is a systematically constructed procedure whereby environmental impacts caused by proposed projects are examined. Geographical Information Systems (GIS) are crucially efficient tools for impact assessment and their use is likely to dramatically increase in the near future. GIS have been applied to a wide range of different impact assessment projects and dams among them have been taken as the case work in this article. EIA Regulation in force in Turkey requires the analysis of steering natural processes that can be adversely affected by the proposed project, particularly in the section of the analysis of the areas with higher landscape value. At this point, the true potential value of GIS lies in its ability to analyze spatial data with accuracy. This study is an attempt to analyze by GIS the areas with higher landscape value in the impact assessment of dam constructions in the case of Seyhan-Köprü Hydroelectric Dam project proposal. A method needs to be defined before the overlapping step by GIS to analyze the areas with higher landscape value. In the case of Seyhan-Köprü Hydroelectric Dam project proposal of the present work, considering the geological conditions and the steep slopes of the area and the type of the project, the most important natural process is erosion. Therefore, the areas of higher erosion risk were considered as the Areas with Higher Landscape Value from the conservation demands points of view.

  3. Reconstructive laparoscopic prolapse surgery to avoid mesh erosions

    Directory of Open Access Journals (Sweden)

    Devassy, Rajesh

    2013-09-01

    Full Text Available Introduction: The objective of the study is to examine the efficacy of the purely laparoscopic reconstructive management of cystocele and rectocele with mesh, to avoid the risk of erosion by the graft material, a well known complication in vaginal mesh surgery. Material and methods: We performed a prospective, single-case, non-randomized study in 325 patients who received laparoscopic reconstructive management of pelvic organe prolaps with mesh. The study was conducted between January 2004 and December 2012 in a private clinic in India. The most common prolapse symptoms were reducible vaginal lump, urinary stress incontinence, constipation and flatus incontinence, sexual dysfunction and dypareunia. The degree e of the prolaps was staged according to POPQ system. The approach was purely laparoscopic and involved the use of polypropylene (Prolene or polyurethane with activated regenerated cellulose coating (Parietex mesh. Results: The mean age was 55 (30–80 years and the most of the patients were multiparous (272/325. The patients received a plastic correction of the rectocele only (138 cases, a cystocele and rectocele (187 cases with mesh. 132 patients had a concomitant total hysterectomy; in 2 cases a laparoscopic supracervical hysterectomy was performed and 190 patients had a laparoscopic colposuspension. The mean operation time was 82.2 (60–210 minutes. The mean follow up was 3.4 (3–5 years. Urinary retention developed in 1 case, which required a new laparoscopical intervention. Bladder injury, observed in the same case was in one session closed with absorbable suture. There were four recurrences of the rectocele, receiving a posterior vaginal colporrhaphy. Erosions of the mesh were not reported or documented. Conclusion: The pure laparoscopic reconstructive management of the cystocele and rectocele with mesh seems to be a safe and effective surgical procedure potentially avoiding the risk of mesh erosions.

  4. The water erosion processes in the retreat erosive of cliff on soft rocks in the province of Cadiz (Spain)

    International Nuclear Information System (INIS)

    Rendon Aragon, J. J.; Gracia Prieto, F. J.; Rio Rodriguez, L. del

    2009-01-01

    The littoral cliffs on soft materials of the Atlantic Cadiz coast show an important activity of the fresh water erosion processes, sometimes even more significant than the marine erosion processes. The connection of the lower cliffs with sandy beaches favours aeolian sand invasion, which fills previous rills and reduces the water erosion intensity by increasing infiltration. Cliff retreat and rill erosion measurement by using erosion sticks has shown very variables values, most of them higher than the estimated error of the employed methods. This indicates the existence of other factors influencing the distribution of water erosion processes along these cliffs, which have to be studied through different techniques. (Author) 5 refs.

  5. Erosion characteristics and horizontal variability for small erosion depths in the Sacramento-San Joaquin River Delta, California, USA

    Science.gov (United States)

    Schoellhamer, David H.; Manning, Andrew J.; Work, Paul A.

    2017-01-01

    Erodibility of cohesive sediment in the Sacramento-San Joaquin River Delta (Delta) was investigated with an erosion microcosm. Erosion depths in the Delta and in the microcosm were estimated to be about one floc diameter over a range of shear stresses and times comparable to half of a typical tidal cycle. Using the conventional assumption of horizontally homogeneous bed sediment, data from 27 of 34 microcosm experiments indicate that the erosion rate coefficient increased as eroded mass increased, contrary to theory. We believe that small erosion depths, erosion rate coefficient deviation from theory, and visual observation of horizontally varying biota and texture at the sediment surface indicate that erosion cannot solely be a function of depth but must also vary horizontally. We test this hypothesis by developing a simple numerical model that includes horizontal heterogeneity, use it to develop an artificial time series of suspended-sediment concentration (SSC) in an erosion microcosm, then analyze that time series assuming horizontal homogeneity. A shear vane was used to estimate that the horizontal standard deviation of critical shear stress was about 30% of the mean value at a site in the Delta. The numerical model of the erosion microcosm included a normal distribution of initial critical shear stress, a linear increase in critical shear stress with eroded mass, an exponential decrease of erosion rate coefficient with eroded mass, and a stepped increase in applied shear stress. The maximum SSC for each step increased gradually, thus confounding identification of a single well-defined critical shear stress as encountered with the empirical data. Analysis of the artificial SSC time series with the assumption of a homogeneous bed reproduced the original profile of critical shear stress, but the erosion rate coefficient increased with eroded mass, similar to the empirical data. Thus, the numerical experiment confirms the small-depth erosion hypothesis. A linear

  6. Wind erosion of soils burned by wildfire

    Science.gov (United States)

    N. S. Wagenbrenner; M. J. Germino; B. K. Lamb; R. B. Foltz; P. R. Robichaud

    2011-01-01

    Wind erosion and aeolian transport processes are largely unstudied in the post-wildfire environment, but recent studies have shown that wind erosion can play a major role in burned landscapes. A wind erosion monitoring system was installed immediately following a wildfire in southeastern Idaho, USA to measure wind erosion from the burned area (Figure 1). This paper...

  7. Robotic weld overlay coatings for erosion control

    Science.gov (United States)

    The erosion of materials by the impact of solid particles has received increasing attention during the past twenty years. Recently, research has been initiated with the event of advanced coal conversion processes in which erosion plays an important role. The resulting damage, termed Solid Particle Erosion (SPE), is of concern primarily because of the significantly increased operating costs which result in material failures. Reduced power plant efficiency due to solid particle erosion of boiler tubes and waterfalls has led to various methods to combat SPE. One method is to apply coatings to the components subjected to erosive environments. Protective weld overlay coatings are particularly advantageous in terms of coating quality. The weld overlay coatings are essentially immune to spallation due to a strong metallurgical bond with the substrate material. By using powder mixtures, multiple alloys can be mixed in order to achieve the best performance in an erosive environment. However, a review of the literature revealed a lack of information on weld overlay coating performance in erosive environments which makes the selection of weld overlay alloys a difficult task. The objective of this project is to determine the effects of weld overlay coating composition and microstructure on erosion resistance. These results will lead to a better understanding of erosion mitigation in CFB's.

  8. Utilisation of Indian Remote Sensing Satellite (IRS) data for assessment of soil erosion process of a watershed in Chhotanagpur plateau region, India

    Science.gov (United States)

    Pramod Krishna, Akhouri

    . Based on maximum likelihood classifier, the study area was classified into suitable land use/land cover classes. Digital elevation model (DEM) was created through contour heights from topographic maps. Watershed based erosion estimation was carried out including assessment of soil erosion due to land use land cover changes. This provides predictive assessment capability in soil erosion studies particularly with methods such as USLE. Soil erosion problem varies largely depending upon climate, topography, soil and land use etc. Multi-factor computations on rainfall erosivity, soil erodibility, topographic, cover and management, and conservation practice were carried out. Quantified details on soil erosion rates were generated in terms of land use land cover classes of the watershed for the years 1996 and 2004. Annual average soil loss for the watershed was calculated and erosion intensity maps were generated. Thus, space data utilized from the satellites IRS1C LISSIII and IRSP6 LISSIII greatly helped in important research assessment of an important land surface process like soil erosion spatially as well as temporally for a watershed under pressures of development, land use changes and land cover fragmentations.

  9. Three procedures for estimating erosion from construction areas

    International Nuclear Information System (INIS)

    Abt, S.R.; Ruff, J.F.

    1978-01-01

    Erosion from many mining and construction sites can lead to serious environmental pollution problems. Therefore, erosion management plans must be developed in order that the engineer may implement measures to control or eliminate excessive soil losses. To properly implement a management program, it is necessary to estimate potential soil losses from the time the project begins to beyond project completion. Three methodologies are presented which project the estimated soil losses due to sheet or rill erosion of water and are applicable to mining and construction areas. Furthermore, the three methods described are intended as indicators of the state-of-the-art in water erosion prediction. The procedures herein do not account for gully erosion, snowmelt erosion, wind erosion, freeze-thaw erosion or extensive flooding

  10. Erosion resistance comparison of alternative surface treatments

    Science.gov (United States)

    Česánek, Z.; Schubert, J.; Houdková, Š.

    2017-05-01

    Erosion is a process characterized by the particle separation and the damage of component functional surfaces. Thermal spraying technology HP/HVOF (High Pressure / High Velocity Oxygen Fuel) is commonly used for protection of component surfaces against erosive wear. Alloy as well as cermet based coatings meet the requirements for high erosion resistance. Wear resistance is in many cases the determining property of required component functioning. The application suitability of coating materials is particularly influenced by different hardness. This paper therefore presents an erosion resistance comparison of alloy and cermet based coatings. The coatings were applied on steel substrates and were subjected to the erosive test using the device for evaluation of material erosion resistance working on the principle of centrifugal erodent flow. Abrasive sand Al2O3 with grain size 212-250 μm was selected as an erosive material. For this purpose, the specimens were prepared by thermal spraying technology HP/HVOF using commercially available powders Stellite 6, NiCrBSi, Cr3C2-25%NiCr, Cr3C2-25%CoNiCrAlY, Hastelloy C-276 and experimental coating TiMoCN-29% Ni. Erosion resistance of evaluated coatings was compared with erosive resistance of 1.4923 high alloyed steel without nitridation and in nitrided state and further with surface treatment using technology PVD. According to the evaluation, the resulting erosive resistance depends not only on the selected erodent and surface protection, but also on the erodent impact angle.

  11. The erosion and erosion products of tungsten and carbon based materials bombarded by high energy pulse electron beam

    International Nuclear Information System (INIS)

    Liu Xiang; Zhang Fu; Xu Zengyu; Liu Yong; Yoshida, N.; Noda, N.

    2002-01-01

    In this paper, the erosion behaviors and erosion products of tungsten and some carbon based materials, such as graphite, C/C composite and B 4 C/Cu functionally graded material, were investigated by using a pulse electron beam to simulate the vertical displacement events (VDE) process. The authors will focus on the forms and differences of erosion products among these testing materials, and make clear to their erosion mechanisms

  12. Auto consolidated cohesive sediments erosion

    International Nuclear Information System (INIS)

    Ternat, F.

    2007-02-01

    Pollutants and suspended matters of a river can accumulate into the sedimentary column. Once deposited, they are submitted to self-weight consolidation processes, ageing and burying, leading to an increase of their erosion resistance. Pollutant fluxes can be related to sedimentary fluxes, determined by threshold laws. In this work, an erosion threshold model is suggested by introducing a cohesion force into the usual force balance. A model of cohesion is developed on the basis of interactions between argillaceous cohesive particles (clays), particularly the Van der Waals force, whose parameterization is ensured by means of granulometry and porosity. Artificial erosion experiments were performed in a recirculating erosion flume with natural cored sediments where critical shear stress measurements were performed. Other analyses provided granulometry and porosity. The results obtained constitute a good database for the literature. The model is then applied to the experimental conditions and gives good agreement with measurements. An example of the accounting for self-weight consolidation processes is finally suggested, before finishing on a Mohr like diagram dedicated to soft cohesive sediment erosion. (author)

  13. Dynamic Analysis of Soil Erosion in Songhua River Watershed

    Science.gov (United States)

    Zhang, Yujuan; Li, Xiuhai; Wang, Qiang; Liu, Jiang; Liang, Xin; Li, Dan; Ni, Chundi; Liu, Yan

    2018-01-01

    In this paper, based on RS and GIS technology and Revised Universal Soil Loss Equation (RUSLE), the soil erosion dynamic changes during the two periods of 1990 and 2010 in Bin County was analyzed by using the Landsat TM data of the two periods, so as to reveal the soil erosion spatial distribution pattern and spatial and temporal dynamic evolution rule in the region. The results showed that: the overall patterns of soil erosion were basically the same in both periods, mainly featuring slight erosion and mild erosion, with the area proportions of 80.68% and 74.71% respectively. The slight and extremely intensive erosion changing rates showed a narrowing trend; mild, moderate and intensive erosion was increasing, with a trend of increased soil erosion; mild and intensive erosion were developing towards moderate erosion and moderate and extremely intensive erosion were progressing towards intensive erosion.

  14. Temperature-dependent erosivity of drinks in a model simulating oral fluid dynamics.

    Science.gov (United States)

    Steiger-Ronay, Valerie; Steingruber, Andrea; Becker, Klaus; Aykut-Yetkiner, Arzu; Wiedemeier, Daniel B; Attin, Thomas

    2018-03-01

    Aim of this investigation was to study the temperature-dependent in vitro enamel erosion of five acidic drinks and citric acid under controlled conditions in an artificial mouth. The erosive potential of Orange juice, Coca-Cola Zero, Sprite Zero, two fruit teas and citric acid (control) was investigated on bovine enamel specimens at temperatures between 5 °C and 55 °C. The pH values and total calcium content of all test drinks were determined. Specimens were immersed into an artificial mouth to imitate physiological oral conditions for 60 h. Cyclic de- and re-mineralization was performed, imitating the intake of six drinks in six h followed by a six-hour remineralization phase, where only artificial saliva ran over the specimens. Total erosive enamel loss was determined by contact profilometry. Differences in substance loss at different temperatures were tested for statistical significance (p-values ≤ 0.05) by means of ANOVA. Rising liquid temperature did not result in a considerable change of pH. Highest substance loss was observed for citric acid (33.6 ± 6 μm to 38.7 ± 6 μm), while only little erosion was induced by fruit tea (0.8 ± 1 μm to 5.9 ± 1 μm). Rising liquid temperature did not result in significantly increased substance loss for citric acid, orange juice and Coca-Cola Zero. Sprite Zero and both fruit teas, however, caused significantly (p < 0.001) more enamel loss at elevated temperature. Not all investigated drinks showed a temperature-induced change in erosivity. For some erosive beverages it can be recommended to keep the consummation temperature as low as possible to decrease the risk of erosive tooth substance loss. Copyright © 2018 Elsevier Ltd. All rights reserved.

  15. Identification of active erosion areas and areas at risk by remote sensing: an example in the Esera Isabena watershed, Central Spanish Pyrenees

    International Nuclear Information System (INIS)

    Alatorre, L. C.; Begueria, S.; Vicente Serrano, S. M.

    2009-01-01

    The identification of eroded areas at basin scale can be very useful for environmental planning and can help to reduce land degradation and sediments yield. In this paper remote sensing technique are used to discriminate eroded areas and areas at risk in a badlands landscape developed on Eocene marls. In the Esera Isabena watershed (Spanish Pyrenees). The spatial distribution, the scarce vegetal cover and the high level of erosion let a good visual and digital discrimination of badlands, as opposed to other land covers and surfaces. A maximum likelihood supervised method was used to discriminate heavily eroded areas (badlands) from scarce or densely vegetated lands. the classification distance was used to obtain thresholds for eroded areas and areas at risk. Two error statistics (sensitivity and specificity), where used to determine the most adequate threshold values. The resulting map shows that most areas at risk are located surrounding the badlands areas. (Author) 8 refs.

  16. Identification of active erosion areas and areas at risk by remote sensing: an example in the Esera Isabena watershed, Central Spanish Pyrenees

    Energy Technology Data Exchange (ETDEWEB)

    Alatorre, L. C.; Begueria, S.; Vicente Serrano, S. M.

    2009-07-01

    The identification of eroded areas at basin scale can be very useful for environmental planning and can help to reduce land degradation and sediments yield. In this paper remote sensing technique are used to discriminate eroded areas and areas at risk in a badlands landscape developed on Eocene marls. In the Esera Isabena watershed (Spanish Pyrenees). The spatial distribution, the scarce vegetal cover and the high level of erosion let a good visual and digital discrimination of badlands, as opposed to other land covers and surfaces. A maximum likelihood supervised method was used to discriminate heavily eroded areas (badlands) from scarce or densely vegetated lands. the classification distance was used to obtain thresholds for eroded areas and areas at risk. Two error statistics (sensitivity and specificity), where used to determine the most adequate threshold values. The resulting map shows that most areas at risk are located surrounding the badlands areas. (Author) 8 refs.

  17. Soil Erosion. LC Science Tracer Bullet.

    Science.gov (United States)

    Buydos, John F., Comp.

    Soil erosion is the detachment and movement of topsoil or soil material from the upper part of the soil profile. It may occur in the form of rill, gully, sheet, or wind erosion. Agents of erosion may be water, wind, glacial ice, agricultural implements, machinery, and animals. Soil conservation measures require a thorough understanding of the…

  18. Comparison of Inconel 625 and Inconel 600 in resistance to cavitation erosion and jet impingement erosion

    International Nuclear Information System (INIS)

    Hu, H.X.; Zheng, Y.G.; Qin, C.P.

    2010-01-01

    Liquid droplet erosion (LDE), which often occurs in bellows made of nickel-based alloys, threatens the security operation of the nuclear power plant. As the candidate materials of the bellows, Inconel 600 and Inconel 625 were both tested for resistance to cavitation erosion (CE) and jet impingement erosion (JIE) through vibratory cavitation equipment and a jet apparatus for erosion-corrosion. Cumulative mass loss vs. exposure time was used to evaluate the erosion rate of the two alloys. The surface and cross-sectional morphologies before and after the erosion tests were observed by scanning electron microscopy (SEM), the inclusions were analyzed by an energy dispersive spectroscopy (EDS), and the surface roughness was also measured by surface roughness tester to illustrate the evolution of erosion process. The results show that the cumulative mass loss of CE of Inconel 625 is about 1/6 that of Inconel 600 and the CE incubation period of the Inconel 625 is 4 times as long as that of the Inconel 600. The micro-morphology evolution of CE process illustrates that the twinning and hardness of the Inconel 625 plays a significant role in CE. In addition, the cumulative mass loss of JIE of Inconel 625 is about 2/3 that of Inconel 600 at impacting angle of 90 o , and almost equal to that of the Inconel 600 at impacting angle of 30 o . Overall, the resistance to CE and JIE of Inconel 625 is much superior to that of Inconel 600.

  19. Coastal Hazard Vulnerability Assessment: A Case Study of Erosion and Flooding on Herschel Island, Yukon Territory, Canada

    Science.gov (United States)

    Radosavljevic, B.; Lantuit, H.; Overduin, P. P.; Fritz, M.

    2015-12-01

    Coastal infrastructure, cultural, and archeological sites are increasingly vulnerable to erosion and flooding along permafrost coasts. Amplified warming of the Arctic, sea level rise, lengthening of the open water period, and a predicted increase in frequency of major storms compound these threats. Mitigation necessitates decision-making tools at an appropriate scale. We present a study of coastal erosion combining it with a flooding risk assessment for the culturally important historic settlement on Herschel Island, a UNESCO World Heritage candidate site. The resulting map may help local stakeholders devise management strategies to cope with rapidly changing environmental conditions. We analyzed shoreline movement using the Digital Shoreline Analysis System (DSAS) after digitizing shorelines from 1952, 1970, and 2011. Using these data, forecasts of shoreline positions were made for 20 and 50 years into the future. Flooding risk was assessed using a cost-distance map based on a high-resolution Light Detection and Ranging (LiDAR) dataset and current Intergovernmental Panel on Climate Change sea level estimates. Widespread erosion characterizes the study area. The rate of shoreline movement for different periods of the study ranges from -5.5 to 2.7 m·a-1 (mean -0.6 m·a-1). Mean coastal retreat decreased from -0.6 m·a-1 to -0.5 m·a-1, for 1952-1970 and 1970-2000, respectively, and increased to -1.3 m·a-1 in the period 2000-2011. Ice-rich coastal sections, and coastal sections most exposed to wave attack exhibited the highest rates of coastal retreat. The geohazard map resulting from shoreline projections and flood risk analysis indicates that most of the area occupied by the historic settlement is at extreme or very high risk of flooding, and some buildings are vulnerable to coastal erosion. The results of this study indicate a greater threat by coastal flooding than erosion. Our assessment may be applied in other locations where limited data are available.

  20. Categorization of erosion control matting.

    Science.gov (United States)

    2012-05-29

    Erosion control is a critical aspect of any Georgia Department of Transportation (GDOT) : construction project, with the extreme negative impacts of high sediment loads in natural : waterways having been well documented. A variety of erosion control ...

  1. Erosion products in disruption simulation experiments

    International Nuclear Information System (INIS)

    Safronov, V.; Arkhipov, N.; Bakhtin, V.; Barsuk, V.; Kurkin, S.; Mironova, E.; Toporkov, D.; Vasenin, S.; Zhitlukhin, A.; Arkhipov, I.; Werle, H.; Wuerz, H.

    1998-01-01

    Erosion of divertor materials under tokamak disruption event presents a serious problem of ITER technology. Erosion restricts the divertor lifetime and leads to production of redeposited layers of the material retaining large amount of tritium, which is a major safety issue for future fusion reactor. Since ITER disruptive heat loads are not achievable in existing tokamaks, material erosion is studied in special simulation experiments. Till now the simulation experiments have focused mainly on investigation of shielding effect and measurement of erosion rate. In the present work the properties of eroded and redeposited graphite are studied under condition typical for hard ITER disruption. (author)

  2. Erosive lichen planus: a therapeutic challenge.

    Science.gov (United States)

    Romero, Williams; Giesen, Laura; Navajas-Galimany, Lucas; Gonzalez, Sergio

    2016-01-01

    Erosive lichen planus is an uncommon variant of lichen planus. Chronic erosions of the soles, accompanied by intense and disabling pain, are some of its most characteristic manifestations. We present the case of a woman who developed oral and plantar erosive lichen planus associated with lichen planus pigmentosus and ungueal lichen planus that were diagnosed after several years. The patient failed to respond to multiple therapies requiring longstanding medication but remained refractory. Knowledge of the treatment options for erosive lichen planus is insufficient. Further research is required to clarify their effectiveness, ideally adopting an evidence-based methodology.

  3. GEOSTATISTICAL BASED SUSCEPTIBILITY MAPPING OF SOIL EROSION AND OPTIMIZATION OF ITS CAUSATIVE FACTORS: A CONCEPTUAL FRAMEWORK

    Directory of Open Access Journals (Sweden)

    ABDULKADIR T. SHOLAGBERU

    2017-11-01

    Full Text Available Soil erosion hazard is the second biggest environmental challenges after population growth causing land degradation, desertification and water deterioration. Its impacts on watersheds include loss of soil nutrients, reduced reservoir capacity through siltation which may lead to flood risk, landslide, high water turbidity, etc. These problems become more pronounced in human altered mountainous areas through intensive agricultural activities, deforestation and increased urbanization among others. However, due to challenging nature of soil erosion management, there is great interest in assessing its spatial distribution and susceptibility levels. This study is thus intend to review the recent literatures and develop a novel framework for soil erosion susceptibility mapping using geostatistical based support vector machine (SVM, remote sensing and GIS techniques. The conceptual framework is to bridge the identified knowledge gaps in the area of causative factors’ (CFs selection. In this research, RUSLE model, field studies and the existing soil erosion maps for the study area will be integrated for the development of inventory map. Spatial data such as Landsat 8, digital soil and geological maps, digital elevation model and hydrological data shall be processed for the extraction of erosion CFs. GISbased SVM techniques will be adopted for the establishment of spatial relationships between soil erosion and its CFs, and subsequently for the development of erosion susceptibility maps. The results of this study include evaluation of predictive capability of GIS-based SVM in soil erosion mapping and identification of the most influential CFs for erosion susceptibility assessment. This study will serve as a guide to watershed planners and to alleviate soil erosion challenges and its related hazards.

  4. Wind and water erosion control on semiarid lands

    International Nuclear Information System (INIS)

    Siddoway, F.H.

    1980-01-01

    Commercial crop production on semiarid lands is difficult because insufficient water is often present to manage the system effectively. Erosion control presents the major management problem. The factors contributing to wind erosion and their interaction have been quantified into a wind erosion equation. The control of wind erosion through agronomic alteration of the various factors is discussed. The quantification and control of water erosion is also discussed with respect to the Universal Soil Loss Equation. Radioisotopes tracers have been used in conjunction with these erosion equations to measure soil losses. (author)

  5. Evaluation of the Erosion on the CFC tiles of the ITER Divertor by means o f FE calculations

    International Nuclear Information System (INIS)

    Schlosser, J.; Bouvet, J.; Riccardi, B.

    2007-01-01

    Full text of publication follows: The vertical target of the ITER divertor is armoured with Carbon Fibre Composite (CFC) mono-blocks in the lower part. This part is subjected to the maximum power and particles loads and, consequently, has a risk of high erosion and a significant risk of failure. In order to calculate the erosion during operation an original methodology has been developed using the CASTEM CEA finite element code. The calculation is based on a series of steady states the mesh being updated at each step of the iteration taking into account the rate of erosion between two steps. The model was developed thanks to the routines developed 10 years ago for the toroidal pump limiter of Tore Supra and takes into account shadowing effect and possible penetration of power into the gap between two mono-blocks. Both physical and chemical sputtering together with sublimation have been included in the code to describe the loss of material by the thermal and particle loads envisaged for ITER normal operation regime. This model has been validated by comparison with analytical or other code results. As erosion instability in normal operation in case of one faulty mono-block besides good ones due to the balanced rate between the various erosion mechanisms at different temperatures can be expected, coherent plasma parameters, which represent the worse cases of erosion in normal operation, have been taken into account to analyse the erosion behaviour of the mono-blocks. The aim of the study was also to evaluate the influence of a mono-block defect on erosion behaviour and the impact of these phenomena on the mono-block acceptance criteria. The calculations have pointed out the occurrence of some erosion instabilities for the studied cases (neighbour mono-block with reduced conductivity or with 90 deg. defects). Moreover it was shown that, when applying 20 MW/m 2 to the erosion model already subjected to the normal condition loads for 10,000 s, the plasma shaping of the

  6. Regional soil erosion assessment based on a sample survey and geostatistics

    Science.gov (United States)

    Yin, Shuiqing; Zhu, Zhengyuan; Wang, Li; Liu, Baoyuan; Xie, Yun; Wang, Guannan; Li, Yishan

    2018-03-01

    worsened the estimation when used as the covariates for the interpolation of soil loss. Due to the unavailability of a 1 : 10 000 topography map for the entire area in this study, the model assisted by the land use, R, and K factors, with a resolution of 250 m, was used to generate the regional assessment of the soil erosion for Shaanxi Province. It demonstrated that 54.3 % of total land in Shaanxi Province had annual soil loss equal to or greater than 5 t ha-1 yr-1. High (20-40 t ha-1 yr-1), severe (40-80 t ha-1 yr-1), and extreme ( > 80 t ha-1 yr-1) erosion occupied 14.0 % of the total land. The dry land and irrigated land, forest, shrubland, and grassland in Shaanxi Province had mean soil loss rates of 21.77, 3.51, 10.00, and 7.27 t ha-1 yr-1, respectively. Annual soil loss was about 207.3 Mt in Shaanxi Province, with 68.9 % of soil loss originating from the farmlands and grasslands in Yan'an and Yulin districts in the northern Loess Plateau region and Ankang and Hanzhong districts in the southern Qingba mountainous region. This methodology provides a more accurate regional soil erosion assessment and can help policymakers to take effective measures to mediate soil erosion risks.

  7. Restorative Rehabilitation of a Patient with Dental Erosion

    OpenAIRE

    AlShahrani, Mohammed Thamer; Haralur, Satheesh B.; Alqarni, Mohammed

    2017-01-01

    Dental erosion is the chemical dissolution of the tooth structure. Factors like eating disorders and gastrointestinal diseases are recognized as intrinsic factors for dental erosion. Advanced stages of dental erosion extensively damage the tooth morphology, consequently affecting both esthetics and functions. Reports indicate the growing prevalence of erosion, and hence knowledge of restorative rehabilitation of tooth erosion is an integral part of the contemporary dental practice. This clini...

  8. A Preliminary Experimental Investigation of Wet Fine Erosion in Two-Phase Flow

    Science.gov (United States)

    Ya, H. H.; Luthfi, Haziq; Ngo, Nguyet-Tran; Hassan, Suhaimi; Pao, William

    2018-03-01

    Solid particles below 62 μm is classified as fine. In oil producing operation, the most commonly used downhole sand screen can only capture solid particles of 140 μm and above. Most predictive erosion model is limited to particle size of 100 μm with single phase flow assumption because it is commonly believed that erosion due to particles below 100 μm is insignificant and typically ignored by oil and gas consultants when proposing facilities design. The objective of this paper is to investigate the impact of fines particle on mild steel plate in two-phase flow at different collision angles. A two phase flow loop was set up. The average size of fine particle was 60 μm, mixed with water with sand to water ratio at 1:65 wt/wt. The mild steel plates were oriented at three different impact angles which are -30°, 30° and 90°, with respect to the horizon. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), surface roughness and Vickers micro hardness techniques were used to quantify the effects of fine particle on the exposed surface.

  9. Erosion Modeling Analysis For Modified DWPF SME Tank

    International Nuclear Information System (INIS)

    LEE, SI

    2004-01-01

    In support of an erosion evaluation for the modified cooling coil guide and its supporting structure in the DWPF SME vessel, a computational model was developed to identify potential sites of high erosion using the same methodology established by previous work. The erosion mechanism identified in the previous work was applied to the evaluation of high erosion locations representative of the actual flow process in the modified coil guide of the SME vessel, abrasive erosion which occurs by high wall shear of viscous liquid. The results show that primary locations of the highest erosion due to the abrasive wall erosion are at the leading edge of the guide, external surface of the insert plate, the tank floor next to the insert plate of the coil guide support, and the upstream lead-in plate. The present modeling results show a good comparison between the original and the modified cases in terms of high erosion sites, as well as the degree of erosion and the calculated shear stress. Wall she ar of the tank floor is reduced by about 30 per cent because of the new coil support plate. Calculations for the impeller speed lower than 103 rpm in the SME showed similar erosion patterns but significantly reduced wall shear stresses and reduced overall erosion. Comparisons of the 103 rpm results with SME measurements indicated that no significant erosion of the tank floor in the SME is to be expected. Thus, it is recommended that the agitator speed of SME does not exceed 103 rpm

  10. Dental erosion among 12 year-old Libyan schoolchildren.

    Science.gov (United States)

    Huew, R; Waterhouse, P J; Moynihan, P J; Maguire, A

    2012-12-01

    As there are limited data on dental erosion in Libya, the aim of this study was to assess the prevalence and severity of dental erosion in a sample of 12 year-old children in Benghazi, Libya. Cross-sectional observational study. Elementary schools in Benghazi, Libya. A random sample of 791 12 year-old children (397 boys and 394 girls) attending 36 schools. Clinical dental examination for erosion using UK National Diet and Nutrition Survey (2000) criteria and self-completion questionnaire. The area and depth of dental erosion affecting the labial and palatal surfaces of the upper permanent incisors and occlusal surfaces of the first permanent molars. Dental erosion was observed in 40.8% of subjects; into enamel affecting 32.5%, into dentine affecting 8.0% and into pulp affecting 0.3% of subjects. Based on area affected, 323 subjects (40.8%) exhibited dental erosion (code > 0), with 32.6% of these subjects having erosion affecting more than two thirds of one or more surfaces examined. Mean total scores for dental erosion for all surfaces per mouth by area and by depth were both 2.69 (sd 3.81). Of the 9492 tooth surfaces examined, 2128 surfaces (22.4%) had dental erosion. Girls had more experience of erosion than boys at all levels of severity (p = 0.001). In a cohort of 12 year-old Libyan schoolchildren, more than one third of children examined showed dental erosion, requiring clinical preventive counselling. Significantly more erosion occurred in girls than boys.

  11. Erosion and stability of a mine soil

    International Nuclear Information System (INIS)

    Wu, T.H.; Stadler, A.T.; Low, C.

    1996-01-01

    Mine soils developed from mine spoils commonly have a wide range of particle size. The slopes of old spoil piles usually are marked by gullies due to years of uncontrolled erosion. These characteristics raise questions about applicability of available theories and models for estimating runoff and erosion. An investigation was made to determine whether available erosion models can work for mine soils and can account for gully erosion. The investigation at an abandoned surface mine consisted of measurement of soil and sediment properties, measurement of runoff and erosion, observations of armor by rock fragments on gully floor, and calculations with available theories of sediment transport and slope stability. The results at this site suggest that (1) predictions with the ANSWERS model have about the same accuracy as those made for agricultural lands; (2) armor provided by rock fragments are temporary as they are periodically removed by debris flows; (3) detachment by rainfall impact is the primary cause of erosion on short steep slopes; and (4) a simplified method can be used for estimating erosion on such slopes

  12. Dental erosion among children aged 3-6 years and its associated indicators.

    Science.gov (United States)

    Tao, Dan-Ying; Hao, Gu; Lu, Hai-Xia; Tian, Yu; Feng, Xi-Ping

    2015-01-01

    To analyze the status quo of dental erosion in 3- to 6-year-old children in Shanghai. A stratified, cluster, multistage random sampling methods was applied to 3- to 6-year-old children in Shanghai in 2012. Both questionnaire and clinical oral examination were performed in the survey. The questionnaire included general information, such as age, gender, parental education, dietary habit, oral health behavior, general medical health, and socioeconomic status. The clinical examination focused on the eroded tooth surface and dental erosion extent. SPSS v19.0 software package was utilized for statistical analysis. A total of 1,837 children aged 3-6 years were randomly selected in Shanghai. The overall dental erosion prevalence was 15.1 percent. Among different age groups, a relatively high prevalence of 17.1 percent was found in the 4-year-old group, and a relatively low prevalence of 12.0 percent was observed in the 3-year-old group. Surprisingly, there was no significant difference among the four age groups. The occurrence of dental erosion was influenced by habits of vinegar/coffee/tea consumption, mother's educational background, birthplace, and regurgitation (P dental erosion prevalence in 3- to 6-year-old children in Shanghai appears to be close to that of other Chinese provinces as well as that observed in most of surveys carried out in different parts of the world. Efforts should be made to raise public awareness about the disease. Moreover, further studies targeted to explore the relationship between dental erosion and risk factors are needed. It is also necessary to establish a unified diagnostic standard for future epidemiological investigations. © 2015 American Association of Public Health Dentistry.

  13. Varioliform erosions in the stomach and duodenum

    Energy Technology Data Exchange (ETDEWEB)

    Lotz, W.; Schulz, D.; Munkel, G.

    1984-04-01

    One thousand five hundred and eighty-three patients who were x-rayed for dyspepsia showed varioliform erosions in 15.3%. Men had an incidence of 9.8%, almost twice as common as in women (5.5%). Mucosal polyps, usually of the hyperplastic type, occurred in 2.4%. 15% of patients with gastric ulcers and 16% of patients with duodenal ulcers had varioliform erosions. On the other hand, amongst patients with erosions, 11% had gastric ulcers and 8.3% duodenal ulcers. The definitions of erosion which have been given in the literature are partly contradictory, and are discussed. Varioliform erosions, also known as complete erosions, may be acute or chronic. They are the third most common cause of bleeding from the upper gastrointestinal tract. With modern radiological methods of examining the stomach, they are no longer a rare finding. 5 figs.

  14. Varioliform erosions in the stomach and duodenum

    International Nuclear Information System (INIS)

    Lotz, W.; Schulz, D.; Munkel, G.

    1984-01-01

    One thousand five hundred and eighty-three patients who were x-rayed for dyspepsia showed varioliform erosions in 15.3%. Men had an incidence of 9.8%, almost twice as common as in women (5.5%). Mucosal polyps, usually of the hyperplastic type, occurred in 2.4%. 15% of patients with gastric ulcers and 16% of patients with duodenal ulcers had varioliform erosions. On the other hand, amongst patients with erosions, 11% had gastric ulcers and 8.3% duodenal ulcers. The definitions of erosion which have been given in the literature are partly contradictory, and are discussed. Varioliform erosions, also known as complete erosions, may be acute or chronic. They are the third most common cause of bleeding from the upper gastrointestinal tract. With modern radiological methods of examining the stomach, they are no longer a rare finding. (orig.) [de

  15. Comparison of Inconel 625 and Inconel 600 in resistance to cavitation erosion and jet impingement erosion

    Energy Technology Data Exchange (ETDEWEB)

    Hu, H.X. [State Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Science, 62 Wencui Road, Shenyang 110016 (China); Zheng, Y.G., E-mail: ygzheng@imr.ac.c [State Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Science, 62 Wencui Road, Shenyang 110016 (China); Qin, C.P. [State Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Science, 62 Wencui Road, Shenyang 110016 (China)

    2010-10-15

    Liquid droplet erosion (LDE), which often occurs in bellows made of nickel-based alloys, threatens the security operation of the nuclear power plant. As the candidate materials of the bellows, Inconel 600 and Inconel 625 were both tested for resistance to cavitation erosion (CE) and jet impingement erosion (JIE) through vibratory cavitation equipment and a jet apparatus for erosion-corrosion. Cumulative mass loss vs. exposure time was used to evaluate the erosion rate of the two alloys. The surface and cross-sectional morphologies before and after the erosion tests were observed by scanning electron microscopy (SEM), the inclusions were analyzed by an energy dispersive spectroscopy (EDS), and the surface roughness was also measured by surface roughness tester to illustrate the evolution of erosion process. The results show that the cumulative mass loss of CE of Inconel 625 is about 1/6 that of Inconel 600 and the CE incubation period of the Inconel 625 is 4 times as long as that of the Inconel 600. The micro-morphology evolution of CE process illustrates that the twinning and hardness of the Inconel 625 plays a significant role in CE. In addition, the cumulative mass loss of JIE of Inconel 625 is about 2/3 that of Inconel 600 at impacting angle of 90{sup o}, and almost equal to that of the Inconel 600 at impacting angle of 30{sup o}. Overall, the resistance to CE and JIE of Inconel 625 is much superior to that of Inconel 600.

  16. Satellite-based estimation of rainfall erosivity for Africa

    NARCIS (Netherlands)

    Vrieling, A.; Sterk, G.; Jong, S.M. de

    2010-01-01

    Rainfall erosivity is a measure for the erosive force of rainfall. Rainfall kinetic energy determines the erosivity and is in turn greatly dependent on rainfall intensity. Attempts for its large-scale mapping are rare. Most are based on interpolation of erosivity values derived from rain gauge

  17. The erosive potential of lollipops

    NARCIS (Netherlands)

    Brand, H.S.; Gambon, D.L.; Paap, A.; Bulthuis, M.S.; Veerman, E.C.I.; Nieuw Amerongen, A.V.

    2009-01-01

    Aim: To determine the erosive potential of several commercially available lollipops and the protective effect of saliva. Methods: The erosive potential of lollipops was determined in vitro by measuring the pH and neutralisable acidity. Subsequently, 10 healthy volunteers tested different types of

  18. [Distribution characteristics and erosion risk of nitrogen and phosphorus in soils of Zhuangmu town in Lake Wabuhu basin].

    Science.gov (United States)

    Li, Ru-Zhong; Zou, Yang; Xu, Jing-Jing; Ding, Gui-Zhen

    2014-03-01

    To understand the loss risk of soil erosion in the Zhuangmu town in Lake Wabuhu watershed, concentration and spatial distribution of nitrogen and phosphorus in 162 surface soil samples collected from the farmlands in ten administrative villages of the town were investigated. The risk assessment was conducted by using the nitrogen and phosphorus index method after speciation analysis of soil nitrogen and phosphorus. Based on ArcGIS technology, the spatial interpolation of total nitrogen (TN), total phosphorus (TP), and bioavailable nitrogen and phosphorus contents as well as nitrogen and phosphorus index values were performed by means of Kriging interpolation. The results show that, generally, average contents of TN and TP were obtained at 1.67 g x kg(-1) and 0.71 g x kg(-1), respectively. And the mean concentration of bioavailable nitrogen and phosphorus were estimated at 0.26 g x kg(-1) and 0.33 g x kg(-1), accounting for 14.93% and 47.30% of TN and TP contents, respectively. Spatially, the samples with high concentration of TN were mostly from Houji, Yangwan and Liuqian villages, whereas the samples sites with higher contents of TP located in Houji, Yangwan and Zaolin villages. The mean values of nitrogen index (NI) and phosphorus index (PI) for the whole town are 2.11 and 2.13, respectively. According to the numeric size of NI and PI, ten villages ranged in the order of Yangwan > Zhuangmu > Xueqiao > Liuqian > Lizhuang > Jinqiao > Zaolin > Zhangwei > Houji > Xugang village. In general, the soil nitrogen loss is dominated by low and medium risks in the Zhuangmu town, and high risk sporadically appears in local area of the Yangwan village. Like the nitrogen, soil phosphorus loss risk also gives priority to low, and above medium risk concentrates in the Yangwan village as well.

  19. Spatial bedrock erosion distribution in a natural gorge

    Science.gov (United States)

    Beer, A. R.; Turowski, J. M.; Kirchner, J. W.

    2015-12-01

    Quantitative analysis of morphological evolution both in terrestrial and planetary landscapes is of increasing interest in the geosciences. In mountainous regions, bedrock channel formation as a consequence of the interaction of uplift and erosion processes is fundamental for the entire surface evolution. Hence, the accurate description of bedrock channel development is important for landscape modelling. To verify existing concepts developed in the lab and to analyse how in situ channel erosion rates depend on the interrelations of discharge, sediment transport and topography, there is a need of highly resolved topographic field data. We analyse bedrock erosion over two years in a bedrock gorge downstream of the Gorner glacier above the town of Zermatt, Switzerland. At the study site, the Gornera stream cuts through a roche moutonnée in serpentine rock of 25m length, 5m width and 8m depth. We surveyed bedrock erosion rates using repeat terrestrial laser scanning (TLS) with an average point spacing of 5mm. Bedrock erosion rates in direction of the individual surface normals were studied directly on the scanned point clouds applying the M3C2 algorithm (Lague et al., 2013, ISPRS). The surveyed erosion patterns were compared to a simple stream erosivity visualisation obtained from painted bedrock sections at the study location. Spatially distributed erosion rates on bedrock surfaces based on millions of scan points allow deduction of millimeter-scale mean annual values of lateral erosion, incision and downstream erosion on protruding streambed surfaces. The erosion rate on a specific surface point is shown to depend on the position of this surface point in the channel's cross section, its height above the streambed and its spatial orientation to the streamflow. Abrasion by impacting bedload was likely the spatially dominant erosion process, as confirmed by the observed patterns along the painted bedrock sections. However, a single plucking event accounted for the half

  20. Application of the Naive Bayesian Classifier to optimize treatment decisions

    International Nuclear Information System (INIS)

    Kazmierska, Joanna; Malicki, Julian

    2008-01-01

    Background and purpose: To study the accuracy, specificity and sensitivity of the Naive Bayesian Classifier (NBC) in the assessment of individual risk of cancer relapse or progression after radiotherapy (RT). Materials and methods: Data of 142 brain tumour patients irradiated from 2000 to 2005 were analyzed. Ninety-six attributes related to disease, patient and treatment were chosen. Attributes in binary form consisted of the training set for NBC learning. NBC calculated an individual conditional probability of being assigned to: relapse or progression (1), or no relapse or progression (0) group. Accuracy, attribute selection and quality of classifier were determined by comparison with actual treatment results, leave-one-out and cross validation methods, respectively. Clinical setting test utilized data of 35 patients. Treatment results at classification were unknown and were compared with classification results after 3 months. Results: High classification accuracy (84%), specificity (0.87) and sensitivity (0.80) were achieved, both for classifier training and in progressive clinical evaluation. Conclusions: NBC is a useful tool to support the assessment of individual risk of relapse or progression in patients diagnosed with brain tumour undergoing RT postoperatively

  1. Cavitation erosion - scale effect and model investigations

    Science.gov (United States)

    Geiger, F.; Rutschmann, P.

    2015-12-01

    The experimental works presented in here contribute to the clarification of erosive effects of hydrodynamic cavitation. Comprehensive cavitation erosion test series were conducted for transient cloud cavitation in the shear layer of prismatic bodies. The erosion pattern and erosion rates were determined with a mineral based volume loss technique and with a metal based pit count system competitively. The results clarified the underlying scale effects and revealed a strong non-linear material dependency, which indicated significantly different damage processes for both material types. Furthermore, the size and dynamics of the cavitation clouds have been assessed by optical detection. The fluctuations of the cloud sizes showed a maximum value for those cavitation numbers related to maximum erosive aggressiveness. The finding suggests the suitability of a model approach which relates the erosion process to cavitation cloud dynamics. An enhanced experimental setup is projected to further clarify these issues.

  2. Investigation of Erosion of Cement-Bentonite via Piping

    Directory of Open Access Journals (Sweden)

    Zijun Wang

    2017-01-01

    Full Text Available Cement-bentonite is one of the main materials used in the seepage barriers to protect earth dams and levees from water erosion. However, the current understanding of the erodibility of the cementitious materials and the interactions between cracked seepage barriers and the water flow is inadequate. Based on the laboratory pinhole erosion test, we first investigated the impacts of cement-bentonite treatments by using the ground granulated blast-furnace slag (GGBS as replacement on the erosion characteristics, compared with the original mixtures; the inclusion of GGBS highlighted a potential advantage against water erosion. In addition, we proposed to calculate the erosion percentage and establish the mathematical relationships between the erosion percentage and different regimes, that is, different curing period, erosion time, and sizes of initial holes. Results showed that enough curing period was critical to avoid the increases of hydraulic conductivity in the macrofabric of the barrier; meanwhile, the materials were eroded quickly at the beginning and slowed down with the erosion time, where the enlargement of the initial creaks would be stabilised at some point in time. Moreover, the sizes of initial holes may affect the erosion situation varying from the sample curing periods.

  3. Erosion of Brassica incana Genetic Resources: Causes and Effects

    Science.gov (United States)

    Muscolo, A.; Settineri, G.; Mallamaci, C.; Papalia, T.; Sidari, M.

    2017-07-01

    Brassica incana Ten., possessing a number of useful agronomic traits, represents a precious genetic resource to be used in plant breeding programs to broaden the genetic base in most Brassica crop species. B. incana that grows on limestone cliffs is at risk of genetic erosion for environmental constraints and human activities. We studied the pedological conditions of a Calabrian site where the B. incana grows, and we correlated the soil properties to the physiological and biochemical aspects of B. incana to identify the causes and effects of the genetic erosion of this species. Our results evidenced that physical soil conditions did not affect B. incana growth and nutraceutical properties; conversely, biological soil properties modified its properties. We identified leaf pigments and secondary metabolites that can be used routinely as early warning indicators of plant threat, to evaluate in a short term the dynamic behavior of plants leading to species extinction.

  4. Cloud forest restoration for erosion control in a Kichwa community of the Ecuadorian central Andes Mountains

    Science.gov (United States)

    Backus, L.; Giordanengo, J.; Sacatoro, I.

    2013-12-01

    The Denver Professional Chapter of Engineers Without Borders (EWB) has begun conducting erosion control projects in the Kichwa communities of Malingua Pamba in the Andes Mountains south of Quito, Ecuador. In many high elevation areas in this region, erosion of volcanic soils on steep hillsides (i.e., food crops. Following a 2011 investigation of over 75 erosion sites, the multidisciplinary Erosion Control team traveled to Malingua Pamba in October 2012 to conduct final design and project implementation at 5 sites. In partnership with the local communities, we installed woody cloud forest species, grass (sig-sig) contour hedges, erosion matting, and rock structures (toe walls, plunge pools, bank armoring, cross vanes, contour infiltration ditches, etc.) to reduce incision rates and risk of slump failures, facilitate aggradation, and hasten revegetation. In keeping with the EWB goal of project sustainability, we used primarily locally available resources. High school students of the community grew 5000 native trees and some naturalized shrubs in a nursery started by the school principal, hand weavers produced jute erosion mats, and rocks were provided by a nearby quarry. Where possible, local rock was harvested from landslide areas and other local erosion features. Based on follow up reports and photographs from the community and EWB travelers, the approach of using locally available materials installed by the community is successful; plants are growing well and erosion control structures have remained in place throughout the November to April rainy season. The community has continued planting native vegetation at several additional erosion sites. Formal monitoring will be conducted in October 2013, followed by analysis of data to determine if induced meandering and other low-maintenance erosion control techniques are working as planned. For comparison of techniques, we will consider installing check dams in comparable gullies. The October 2013 project will also

  5. Wind erosion processes and control

    Science.gov (United States)

    Wind erosion continues to threaten the sustainability of our nations' soil, air, and water resources. To effectively apply conservation systems to prevent wind driven soil loss, an understanding of the fundamental processes of wind erosion is necessary so that land managers can better recognize the ...

  6. Anthropogenic Increase Of Soil Erosion In The Gangetic Plain Revealed By Geochemical Budget Of Erosion

    Science.gov (United States)

    Galy, V.; France-Lanord, C.; Galy, A.; Gaillardet, J.

    2007-12-01

    Tectonic and climatic factors are the key natural variables controlling the erosion through complex interactions. Nonetheless, over the last few hundred years, human activity also exerts a dominant control in response to extensive land use. The geochemical budget of erosion allows the balance between the different erosion processes to be quantified. The chemical composition of river sediment results from the chemical composition of the source rock modified by (1) weathering reactions occurring during erosion and (2) physical segregation during transport. If erosion is at steady state, the difference between the chemical composition of source rocks and that of river sediments must therefore be counterbalanced by the dissolved flux. However, climatic variations or anthropic impact can induce changes in the erosion distribution in a given basin resulting in non steady state erosion. Using a mass balance approach, the comparison of detailed geochemical data on river sediments with the current flux of dissolved elements allows the steady state hypothesis to be tested. In this study, we present a geochemical budget of weathering for the Ganga basin, one of the most densely populated basin in the world, based on detailed sampling of Himalayan rivers and of the Ganga in the delta. Sampling includes depth profile in the river, to assess the variability generated by transport processes. Himalayan river sediments are described by the dilution of an aluminous component (micas + clays + feldspars) by quartz. Ganga sediments on the other hand correspond to the mixing of bedload, similar to coarse Himalayan sediments, with an aluminous component highly depleted in alkaline elements. Compared with the dissolved flux, the depletion of alkaline elements in Ganga sediments shows that the alkaline weathering budget is imbalanced. This imbalance results from an overabundance of fine soil material in the Ganga sediment relative to other less weathered material directly derived from

  7. Dental erosion among 12-year-old schoolchildren: a population-based cross-sectional study in South Brazil.

    Science.gov (United States)

    Alves, Luana Severo; Brusius, Carolina Doege; Damé-Teixeira, Nailê; Maltz, Marisa; Susin, Cristiano

    2015-12-01

    To assess the epidemiology and risk indicators for dental erosion among 12-year-old schoolchildren in South Brazil. A population-based cross-sectional survey was conducted in Porto Alegre, Brazil, using a representative sample of 12-year-old schoolchildren (n = 1,528). Dental erosion was recorded according to the Basic Erosive Wear Examination (BEWE) index. Parents answered questions on socio-economic status, brushing frequency and general health. Schoolchildren answered questions on dietary habits. Anthropometric data were collected. Statistical analysis included logistic and Poisson regression models. The prevalence of dental erosion was 15% [95% confidence interval (95% CI): 13.6-16.5], being mainly mild erosion. Boys [odds ratio (OR) = 1.57, 95% CI: 1.17-2.10], private school attendees (OR = 1.45, 95% CI: 1.01-2.06) and schoolchildren reporting the daily consumption of soft drinks (OR = 5.04, 95% CI: 1.17-21.71) were more likely to have at least one tooth with dental erosion. Gender [boys, rate ratio (RR) = 1.66, 95% CI: 1.28-2.17], type of school (private, RR = 1.89, 95% CI: 1.53-2.35), the consumption of soft drinks (sometimes: RR = 5.27, 95% CI: 1.46-19.05; daily: RR = 6.82, 95% CI: 1.39-33.50) and the daily consumption of lemon (RR = 1.49, 95% CI: 1.11-2.00) were significantly associated with the number of affected surfaces. The present study found a moderate prevalence of dental erosion among young schoolchildren, with mild erosion being the most prevalent condition. Socio demographic variables and dietary habits were associated with dental erosion in this population. © 2015 FDI World Dental Federation.

  8. Restorative Rehabilitation of a Patient with Dental Erosion.

    Science.gov (United States)

    AlShahrani, Mohammed Thamer; Haralur, Satheesh B; Alqarni, Mohammed

    2017-01-01

    Dental erosion is the chemical dissolution of the tooth structure. Factors like eating disorders and gastrointestinal diseases are recognized as intrinsic factors for dental erosion. Advanced stages of dental erosion extensively damage the tooth morphology, consequently affecting both esthetics and functions. Reports indicate the growing prevalence of erosion, and hence knowledge of restorative rehabilitation of tooth erosion is an integral part of the contemporary dental practice. This clinical report describes an adult patient with gastroesophageal reflux induced dental erosion involving the palatal surface of the maxillary anterior teeth. The extensive involvement of the palatal surfaces compromised the esthetics, incisal guidance, and functional occlusal efficiency. Indirect all-ceramic restorations were utilized to restore the esthetics and occlusal reconstruction. In conclusion, patients affected by severe dental erosion require prosthetic rehabilitation besides the management of the associated medical condition.

  9. Restorative Rehabilitation of a Patient with Dental Erosion

    Directory of Open Access Journals (Sweden)

    Mohammed Thamer AlShahrani

    2017-01-01

    Full Text Available Dental erosion is the chemical dissolution of the tooth structure. Factors like eating disorders and gastrointestinal diseases are recognized as intrinsic factors for dental erosion. Advanced stages of dental erosion extensively damage the tooth morphology, consequently affecting both esthetics and functions. Reports indicate the growing prevalence of erosion, and hence knowledge of restorative rehabilitation of tooth erosion is an integral part of the contemporary dental practice. This clinical report describes an adult patient with gastroesophageal reflux induced dental erosion involving the palatal surface of the maxillary anterior teeth. The extensive involvement of the palatal surfaces compromised the esthetics, incisal guidance, and functional occlusal efficiency. Indirect all-ceramic restorations were utilized to restore the esthetics and occlusal reconstruction. In conclusion, patients affected by severe dental erosion require prosthetic rehabilitation besides the management of the associated medical condition.

  10. Erosion of the first wall of Tokamaks

    International Nuclear Information System (INIS)

    Guseva, M.I.; Ionova, E.S.; Martynenko, Yu.V.

    1980-01-01

    An estimate of the rate of erosion of the wall due to sputtering and blistering requires knowledge of the fluxes and energies of the particles which go from the plasma to the wall, of the sputtering coefficients S, and of the erosion coefficients S* for blistering. The overall erosion coefficient is equal to the sum of the sputtering coefficient and the erosion coefficient for blistering. Here the T-20 Tokamak is examined as an example of a large-scale Tokamak. 18 refs

  11. Three Gorges Reservoir Area: soil erosion under natural condition vs. soil erosion under current land use

    Science.gov (United States)

    Schönbrodt, Sarah; Behrens, Thorsten; Scholten, Thomas

    2010-05-01

    Apparently, the current most prominent human-induced example for large scale environmental impact is the Three Gorges Dam in China. The flooding alongside the Yangtze River, and its tributaries results in a vast loss of settlement and farmland area with productive, fertile valley soils. Due to the associated high land use dynamic on uphill-sites, the soil resources are underlying high land use pressure. Within our study, the soil erosion under natural conditions is compared to the soil erosion under current land use after the impoundment. Both were modeled using the empirical Universal Soil Loss Equation (USLE) which is able to predict long-term annual soil loss with limited data. The database consists of digital terrain data (45 m resolution DEM, erosive slope length based on Monte-Carlo-Aggregation according to Behrens et al. (2008)), field investigations of recent erosion forms, and literature studies. The natural disposition to soil erosion was calculated considering the USLE factors R, S, and K. The soil erosion under current land use was calculated taking into account all USLE factors. The study area is the catchment of the Xiangxi River in the Three Gorges Reservoir area. Within the Xiangxi Catchment (3,200 km²) the highly dynamic backwater area (580 km²), and two micro-scale study sites (Xiangjiaba with 2.8 km², and Quyuan with 88 km²) are considered more detailed as they are directly affected by the river impoundment. Central features of the Xiangxi Catchment are the subtropical monsoon climate, an extremely steep sloping relief (mean slope angle 39°, SD 22.8°) artificially fractured by farmland terraces, and a high soil erodibility (mean K factor 0.37, SD 0.13). On the catchment scale the natural disposition to soil erosion makes up to mean 518.0 t ha-1 a-1. The maximum potential soil loss of 1,730.1 t ha-1 a-1 under natural conditions is reached in the Quyuan site (mean 635.8 t ha-1 a-1) within the backwater area (mean 582.9 t ha-1 a-1). In the

  12. Fundamental study on cavitation erosion in liquid metal. Effect of liquid parameter on cavitation erosion in liquid metals (Joint research)

    International Nuclear Information System (INIS)

    Hattori, Shuji; Kurachi, Hiroaki; Inoue, Fumitaka; Watashi, Katsumi; Tsukimori, Kazuyuki; Yada, Hiroki; Hashimoto, Takashi

    2009-02-01

    Cavitation erosion, which possibly occurs on the surfaces of fluid machineries and components contacting flowing liquid and causes sponge-like damage on the material surface, is important problem, since it may become the cause of performance deduction, life shortening, noise, vibration of mechanical components and moreover failure of machine. Research on cavitation erosion in liquid metal is very important to confirm the safety of fast breeder reactor using sodium coolant and to avoid serious damage of the target vessel of spallation neutron source containing liquid-mercury. But the research on cavitation erosion in liquid metal has been hardly performed because of its specially in comparison with that in water. In this study, a cavitation erosion test apparatus was developed to carry out the erosion tests in low-temperature liquid metals. Cavitation erosion tests were carried out in liquid lead-bismuth alloy and in deionized water. We discuss the effect of liquid parameters and temperature effects on the erosion rate. We reach to the following conclusions. The erosion rate was evaluated in terms of a relative temperature which was defind as the percentage between freezing and boiling points. At 14degC relative temperature, the erosion rate is 10 times in lead-bismuth alloy, and 2 to 5 times in sodium, compared with that in deionized water. At 14degC relative temperature, the erosion rate can be evaluated in terms of the following parameter. 1 / (1/ρ L /C L +1/ρ S C S )√ρ L . Where ρ is the material density and c is the velocity of sound, L and S denote liquid and solid. In the relative temperature between 14 and 30degC, the temperature dependence on the erosion rate is due to the increase in vapor pressure. (author)

  13. Just-in-time adaptive classifiers-part II: designing the classifier.

    Science.gov (United States)

    Alippi, Cesare; Roveri, Manuel

    2008-12-01

    Aging effects, environmental changes, thermal drifts, and soft and hard faults affect physical systems by changing their nature and behavior over time. To cope with a process evolution adaptive solutions must be envisaged to track its dynamics; in this direction, adaptive classifiers are generally designed by assuming the stationary hypothesis for the process generating the data with very few results addressing nonstationary environments. This paper proposes a methodology based on k-nearest neighbor (NN) classifiers for designing adaptive classification systems able to react to changing conditions just-in-time (JIT), i.e., exactly when it is needed. k-NN classifiers have been selected for their computational-free training phase, the possibility to easily estimate the model complexity k and keep under control the computational complexity of the classifier through suitable data reduction mechanisms. A JIT classifier requires a temporal detection of a (possible) process deviation (aspect tackled in a companion paper) followed by an adaptive management of the knowledge base (KB) of the classifier to cope with the process change. The novelty of the proposed approach resides in the general framework supporting the real-time update of the KB of the classification system in response to novel information coming from the process both in stationary conditions (accuracy improvement) and in nonstationary ones (process tracking) and in providing a suitable estimate of k. It is shown that the classification system grants consistency once the change targets the process generating the data in a new stationary state, as it is the case in many real applications.

  14. Natural and anthropogenic rates of soil erosion

    Science.gov (United States)

    Regions of land that are brought into crop production from native vegetation typically undergo a period of soil erosion instability, and long term erosion rates are greater than for natural lands as long as the land continues being used for crop production. Average rates of soil erosion under natur...

  15. Dietary assessment and counseling for dental erosion.

    Science.gov (United States)

    Marshall, Teresa A

    2018-02-01

    Dental erosion occurs after exposure to intrinsic or extrinsic acids. Exposure to intrinsic gastrointestinal acids is associated with anorexia nervosa, bulimia nervosa, rumination syndrome, or gastroesophageal reflux. Extrinsic dietary acids from foods or beverages also can cause erosion, particularly when exposure is prolonged by holding or swishing behaviors. Clinicians should screen patients exhibiting dental erosion for anorexia nervosa, bulimia nervosa, rumination syndrome, and gastroesophageal reflux disease. Clinicians should screen patients without a medical explanation for their erosion for exposure to acidic foods and beverages, particularly for habits that prolong exposure. Identification of intrinsic and extrinsic acid exposures and recommendations to minimize exposures are important to prevent erosion and maintain oral health. Copyright © 2018 American Dental Association. Published by Elsevier Inc. All rights reserved.

  16. The effect of pH on the erosion of dentine and enamel by dietary acids in vitro.

    Science.gov (United States)

    West, N X; Hughes, J A; Addy, M

    2001-09-01

    The reported incidence of tooth erosion caused by acidic soft drinks has been increasingly documented. Citric and phosphoric acids are the two main dietary acids present in these soft drinks. Many variables need to be determined in order to assess risk factors for dental erosion caused by beverage consumption including pH, titratable acidity, pKa, buffering capacity, hence the aim of these in vitro investigations. Methodologies included profiling flat enamel and dentine samples (acidic solutions adjusted with alkali over the available pH range; citric, phosphoric and hydrochloric acid were adjusted with sodium hydroxide and citric acid with trisodium citrate. Tissue loss was calculated by profilometry. Results showed that under these conditions citric acid caused far more erosion over the pH range employed than phosphoric acid for both tissue types. Citric acid compared with hydrochloric acid highlighted dissolution and chelation effects. Phosphoric acid caused minimal erosion over pH 3 for enamel and pH 4 for dentine. These factors could be considered in order to reduce the erosivity of acidic soft drinks.

  17. Soil erosion in Slovene Istria

    Directory of Open Access Journals (Sweden)

    Matjaž Mikoš

    2009-12-01

    Full Text Available From the end of nineties of the 20th century, intense hydrologic and geomorphologic research is taking place in the Slovene Istria. As a part of this research also studies on soil erosion were undertaken in the period from 2005 to 2008. The field measurements were under taken onclosed 1m2 large erosion plots under three different land uses (on bare soils in an olive grove, on an overgrown meadow, in a forest, placed south of the Marezige village in the Rokava River basin.We show weekly measurements of surface erosion (interrill erosion for the period of 13 months (the end of March 2005 – the end of April 2006, as well as monthly and seasonal averages together with selected linear statistical correlations between soil erosion and weather parameters.From May 2005 to April 2006 the interrill erosion on bare soils in an olive grove with an inclination of 5.5° amounted to 9013 g/m2 (90 t/ha that corresponds to surface lowering rate of 8.5 mm/yr; on an overgrown meadow with an inclination of 9.4° it amounted to 168 g/m2 (1,68 t/ha that corresponds to surface lowering rate of 0.16 mm//yr; and in a forest with an inclination of 7.8° it amounted to 391 g/m2 (3,91 t/ha and in a forest with an inclination of 21.4° it amounted to 415 g/m2 (4,15 t/ha, respectively, that corresponds to surface lowering rate of 0.4 mm/yr.

  18. Bentonite erosion. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Birgersson, Martin; Boergesson, Lennart; Hedstroem, Magnus; Karnland, Ola; Nilsson, Ulf (Clay Technology AB, Lund (Sweden))

    2009-12-15

    Low saline water may reach KBS-3 repository depth, e.g. during periods of glaciation. Under such aqueous conditions, the montmorillonite part of the bentonite buffer might transform into a sol and thereby be transported away with flowing water in fractures. The primary aim with this report is to improve the understanding of the basic principles for this possible montmorillonite particle release. The report includes experimental and theoretical work performed at Clay Technology. Natural bentonite and ion-exchanged purified montmorillonite from three different geographical origins, Wyoming (U.S.), Milos (Greece) and Kutch (India) have been studied. Experimental and/or theoretical investigations have been performed with respect to: - Free swelling ability; - Rheological properties; - Rate of bentonite loss into fractures; - Filtering; - Ion exchange; - Sol formation ability; - Ion diffusion; - Mass loss due to erosion. The performed erosion experiments show that erosion does not occur in a mixed calcium/sodium montmorillonite with at least 20% calcium in exchange positions, when the external solution contains above 4 mM charge equivalents. This result is in agreement with the presented conceptual view of sol formation and measured equilibrium properties in mixed calcium/sodium montmorillonite. The findings imply that the buffer will be stable for non-glacial conditions. However, erosion due to sol formation cannot be ruled out for glacial conditions.

  19. Bentonite erosion. Final report

    International Nuclear Information System (INIS)

    Birgersson, Martin; Boergesson, Lennart; Hedstroem, Magnus; Karnland, Ola; Nilsson, Ulf

    2009-12-01

    Low saline water may reach KBS-3 repository depth, e.g. during periods of glaciation. Under such aqueous conditions, the montmorillonite part of the bentonite buffer might transform into a sol and thereby be transported away with flowing water in fractures. The primary aim with this report is to improve the understanding of the basic principles for this possible montmorillonite particle release. The report includes experimental and theoretical work performed at Clay Technology. Natural bentonite and ion-exchanged purified montmorillonite from three different geographical origins, Wyoming (U.S.), Milos (Greece) and Kutch (India) have been studied. Experimental and/or theoretical investigations have been performed with respect to: - Free swelling ability; - Rheological properties; - Rate of bentonite loss into fractures; - Filtering; - Ion exchange; - Sol formation ability; - Ion diffusion; - Mass loss due to erosion. The performed erosion experiments show that erosion does not occur in a mixed calcium/sodium montmorillonite with at least 20% calcium in exchange positions, when the external solution contains above 4 mM charge equivalents. This result is in agreement with the presented conceptual view of sol formation and measured equilibrium properties in mixed calcium/sodium montmorillonite. The findings imply that the buffer will be stable for non-glacial conditions. However, erosion due to sol formation cannot be ruled out for glacial conditions.

  20. Rainfall erosivity and sediment load over the Poyang Lake Basin under variable climate and human activities since the 1960s

    Science.gov (United States)

    Gu, Chaojun; Mu, Xingmin; Gao, Peng; Zhao, Guangju; Sun, Wenyi; Yu, Qiang

    2018-03-01

    Accelerated soil erosion exerts adverse effects on water and soil resources. Rainfall erosivity reflects soil erosion potential driven by rainfall, which is essential for soil erosive risk assessment. This study investigated the spatiotemporal variation of rainfall erosivity and its impacts on sediment load over the largest freshwater lake basin of China (the Poyang Lake Basin, abbreviate to PYLB). The spatiotemporal variations of rainfall erosivity from 1961 to 2014 based on 57 meteorological stations were detected using the Mann-Kendall test, linear regression, and kriging interpolation method. The sequential t test analysis of regime shift (STARS) was employed to identify the abrupt changes of sediment load, and the modified double mass curve was used to assess the impacts of rainfall erosivity variability on sediment load. It was found that there was significant increase (P change-points were identified in both 1985 and 2003. It was found that take annual rainfall erosivity as the explanatory variables of the double mass curves is more reasonable than annual rainfall and erosive rainfall. The estimation via the modified double mass curve demonstrated that compared with the period before change-point (1961-1984), the changes of rainfall erosivity increased 8.0 and 2.1% of sediment load during 1985-2002 and 2003-2014, respectively. Human activities decreased 50.2 and 69.7% of sediment load during the last two periods, which indicated effects of human activities on sediment load change was much larger than that of rainfall erosivity variability in the PYLB.

  1. PROBLEMS OF SOIL PROTECTION FROM EROSION

    OpenAIRE

    M. Voloshuk; Natalia Kiriak

    2007-01-01

    In this article the problems of soil protection from erosion in Moldova are considered. The history (evolution) of erosive processes is generalized, the first items of information on presence washed off soils are marked. Purposeful study of soil erosion, development of measures of struggle with it were begun in Moldova at the end of 40 years. In connection with transition to new economic methods of conducting economy (farmers, rent, privatization of land) before pedologist, the experts of des...

  2. Soil erosion in humid regions: a review

    Science.gov (United States)

    Daniel J. Holz; Karl W.J. Williard; Pamela J. Edwards; Jon E. Schoonover

    2015-01-01

    Soil erosion has significant implications for land productivity and surface water quality, as sediment is the leading water pollutant worldwide. Here, erosion processes are defined. The dominant factors influencing soil erosion in humid areas are reviewed, with an emphasis on the roles of precipitation, soil moisture, soil porosity, slope steepness and length,...

  3. Erosion prediction for alpine slopes: a symbiosis of remote sensing and a physical based erosion model

    Science.gov (United States)

    Kaiser, Andreas; Neugirg, Fabian; Haas, Florian; Schindewolf, Marcus; Schmidt, Jürgen

    2014-05-01

    As rainfall simulations represent an established tool for quantifying soil detachment on cultivated area in lowlands and low mountain ranges, they are rarely used on steep slopes high mountain ranges. Still this terrain represents productive sediment sources of high morphodynamic. A quantitative differentiation between gravitationally and fluvially relocated material reveals a major challenge in understanding erosion on steep slopes: does solifluction as a result of melting in spring or heavy convective rainstorms during summer cause the essential erosion processes? This paper aims to answer this question by separating gravitational mass movement (solifluction, landslides, mudflow and needle ice) and runoff-induced detachment. First simulated rainstorm experiments are used to assess the sediment production on bare soil on a strongly inclined plot (1 m², 42°) in the northern limestone Alps. Throughout precipitation experiments runoff and related suspended sediments were quantified. In order to enlarge slope length virtually to around 20 m a runoff feeding device is additionally implemented. Soil physical parameters were derived from on-site sampling. The generated data is introduced to the physically based and catchment-scaled erosion model EROSION 3D to upscale plot size to small watershed conditions. Thus infiltration, runoff, detachment, transport and finally deposition can be predicted for single rainstorm events and storm sequences. Secondly, in order to separate gravitational mass movements and water erosion, a LiDAR and structure-from-motion based monitoring approach is carried out to produce high-resolution digital elevation models. A time series analysis of detachment and deposition from different points in time is implemented. Absolute volume losses are then compared to sediment losses calculated by the erosion model as the latter only generates data that is connected to water induced hillside erosion. This methodology will be applied in other watersheds

  4. Hybrid classifiers methods of data, knowledge, and classifier combination

    CERN Document Server

    Wozniak, Michal

    2014-01-01

    This book delivers a definite and compact knowledge on how hybridization can help improving the quality of computer classification systems. In order to make readers clearly realize the knowledge of hybridization, this book primarily focuses on introducing the different levels of hybridization and illuminating what problems we will face with as dealing with such projects. In the first instance the data and knowledge incorporated in hybridization were the action points, and then a still growing up area of classifier systems known as combined classifiers was considered. This book comprises the aforementioned state-of-the-art topics and the latest research results of the author and his team from Department of Systems and Computer Networks, Wroclaw University of Technology, including as classifier based on feature space splitting, one-class classification, imbalance data, and data stream classification.

  5. Development of a mobile application based on RUSLE model to predict erosion in olive groves

    Science.gov (United States)

    Marín Moreno, Víctor Javier; Redel, María Dolores; Taguas, Encarnación V.

    2017-04-01

    Environmental impact of agriculture in fragile areas such as the Mediterranean Basin due to its scarcity and/or variability of water resources or to their susceptibility to soil erosion may be extremely damaging. Over 96% of the world's olive oil is produced in Mediterranean countries (FAOSTAT, 2014). Suitable managements and environmental evaluations of the conditions in olive cultivation farms is of major relevance for countries such as Spain, particularly in Andalusia (in Southern Spain) with an olive orchard area of 1.5 Mha (CAP, 2016). The average erosion rates in olive orchard in Southern Spain are approximately 19 tons.ha-1.year-1. It is worth noting how 23% of this surface presents high or very high erosion rates with values over 50 tons.ha-1.year-1 (Areal, 2014). Most of farmers implement soil conservation practices only when have they perceived high erosion risk (Franco, 2011: Taguas and Gómez, 2015). On the other hand, technicians also require proper technological tools to evaluate in a straightforward way, soil loss risk in the field. Simple tools integrated into smartphones may enable us to evaluate soil erosion rates through minimum information; which would be a great help in raising farmer awareness as well as in environmental control. In this work, the preliminary version of RIESGO (Risk Index for Erosion Soil in Olive Groves) , -an APP mobile based in SECO (Soil Erosion Calculator in Olives; Marín-Moreno et al. 2013) that promises broad functionality to identify soil loss risk in the field,- is presented. Features such as simple screens, a reduced group of input data, calculations for R and K factors based on environmental information of Andalusia which are identified from geographical coordinates and a new method of obtaining factor C from empirical data have been integrated to fit its use in the field. RIESGO is and hybrid application which was programmed by using web technologies HTML, CSS and JavaScript, and built with Visual Studio Tools for

  6. Modelling rainfall erosion resulting from climate change

    Science.gov (United States)

    Kinnell, Peter

    2016-04-01

    It is well known that soil erosion leads to agricultural productivity decline and contributes to water quality decline. The current widely used models for determining soil erosion for management purposes in agriculture focus on long term (~20 years) average annual soil loss and are not well suited to determining variations that occur over short timespans and as a result of climate change. Soil loss resulting from rainfall erosion is directly dependent on the product of runoff and sediment concentration both of which are likely to be influenced by climate change. This presentation demonstrates the capacity of models like the USLE, USLE-M and WEPP to predict variations in runoff and erosion associated with rainfall events eroding bare fallow plots in the USA with a view to modelling rainfall erosion in areas subject to climate change.

  7. RUSLE2015: Modelling soil erosion at continental scale using high resolution input layers

    Science.gov (United States)

    Panagos, Panos; Borrelli, Pasquale; Meusburger, Katrin; Poesen, Jean; Ballabio, Cristiano; Lugato, Emanuele; Montanarella, Luca; Alewell, Christine

    2016-04-01

    Soil erosion by water is one of the most widespread forms of soil degradation in the Europe. On the occasion of the 2015 celebration of the International Year of Soils, the European Commission's Joint Research Centre (JRC) published the RUSLE2015, a modified modelling approach for assessing soil erosion in Europe by using the best available input data layers. The objective of the recent assessment performed with RUSLE2015 was to improve our knowledge and understanding of soil erosion by water across the European Union and to accentuate the differences and similarities between different regions and countries beyond national borders and nationally adapted models. RUSLE2015 has maximized the use of available homogeneous, updated, pan-European datasets (LUCAS topsoil, LUCAS survey, GAEC, Eurostat crops, Eurostat Management Practices, REDES, DEM 25m, CORINE, European Soil Database) and have used the best suited approach at European scale for modelling soil erosion. The collaboration of JRC with many scientists around Europe and numerous prominent European universities and institutes resulted in an improved assessment of individual risk factors (rainfall erosivity, soil erodibility, cover-management, topography and support practices) and a final harmonized European soil erosion map at high resolution. The mean soil loss rate in the European Union's erosion-prone lands (agricultural, forests and semi-natural areas) was found to be 2.46 t ha-1 yr-1, resulting in a total soil loss of 970 Mt annually; equal to an area the size of Berlin (assuming a removal of 1 meter). According to the RUSLE2015 model approximately 12.7% of arable lands in the European Union is estimated to suffer from moderate to high erosion(>5 t ha-1 yr-1). This equates to an area of 140,373 km2 which equals to the surface area of Greece (Environmental Science & Policy, 54, 438-447; 2015). Even the mean erosion rate outstrips the mean formation rate (walls and contouring) through the common agricultural

  8. River Bank Erosion and the Influence of Environmental Flow Management

    Science.gov (United States)

    Vietz, Geoff J.; Lintern, Anna; Webb, J. Angus; Straccione, David

    2018-03-01

    Environmental flows aim to influence river hydrology to provide appropriate physical conditions for ecological functioning within the restrictions of flow regulation. The hydrologic characteristics of flow events, however, may also lead to unintended morphologic effects in rivers, such as increases in riverbank erosion beyond natural rates. This may negatively impact habitat for biota, riparian infrastructure, and land use. Strategic environmental flow delivery linked to monitoring and adaptive management can help mitigate risks. We monitor riverbank condition (erosion and deposition) relative to environmental flows on the Goulburn River, Victoria, Australia. We describe the process of adaptive management aimed at reducing potential impacts of flow management on bank condition. Field measurements (erosion pins) quantify the hydrogeomorphic response of banks to the delivery of planned and natural flow events. Managed flows provide opportunities for monitoring riverbank response to flows, which in turn informs planning. The results demonstrate that environmental flows have little influence on bank erosion and visual perceptions in the absence of monitoring are an unreliable guide. This monitoring project represents a mutually beneficial, science-practice partnership demonstrating that a traditional `know then do' approach can be foreshortened by close collaboration between researchers and managers. To do so requires transparent, often informal lines of communication. The benefits for researchers-a more strategic and targeted approach to monitoring activities; and benefits for the practitioners-reduced time between actions and understanding response; mean that a learn by doing approach is likely to have better outcomes for researchers, stakeholders, the public, and the environment.

  9. River Bank Erosion and the Influence of Environmental Flow Management.

    Science.gov (United States)

    Vietz, Geoff J; Lintern, Anna; Webb, J Angus; Straccione, David

    2018-03-01

    Environmental flows aim to influence river hydrology to provide appropriate physical conditions for ecological functioning within the restrictions of flow regulation. The hydrologic characteristics of flow events, however, may also lead to unintended morphologic effects in rivers, such as increases in riverbank erosion beyond natural rates. This may negatively impact habitat for biota, riparian infrastructure, and land use. Strategic environmental flow delivery linked to monitoring and adaptive management can help mitigate risks. We monitor riverbank condition (erosion and deposition) relative to environmental flows on the Goulburn River, Victoria, Australia. We describe the process of adaptive management aimed at reducing potential impacts of flow management on bank condition. Field measurements (erosion pins) quantify the hydrogeomorphic response of banks to the delivery of planned and natural flow events. Managed flows provide opportunities for monitoring riverbank response to flows, which in turn informs planning. The results demonstrate that environmental flows have little influence on bank erosion and visual perceptions in the absence of monitoring are an unreliable guide. This monitoring project represents a mutually beneficial, science-practice partnership demonstrating that a traditional 'know then do' approach can be foreshortened by close collaboration between researchers and managers. To do so requires transparent, often informal lines of communication. The benefits for researchers-a more strategic and targeted approach to monitoring activities; and benefits for the practitioners-reduced time between actions and understanding response; mean that a learn by doing approach is likely to have better outcomes for researchers, stakeholders, the public, and the environment.

  10. Erosion by rain in the western Congo

    International Nuclear Information System (INIS)

    Ploey, J. de

    1967-01-01

    Vast expanses of the western part of central and southern Africa are covered with uniform, sandy formations of the Kalahari type. The topography of these areas and their present morphological characteristics are mainly the result of erosion by rain. Information on the hydrology of the surface waters in these areas is fairly limited and is insufficient to permit any conclusions regarding the way in which erosion by rain takes place. To obtain a better understanding of these phenomena, the author devised a series of experiments based on the use of 46 Sc-labelled radioactive sand. These experiments began at the beginning of the 1964/65 rainy season and are continuing. The experimental plot corresponds to convex and rectilinear portions of a hillside with a slope varying between 0 and 12 degrees. The vegetation consists of grassy savannah of substeppe appearance and secondary forests. Series of labelled samples were placed successively on the surface of the experimental plot and the erosive effect of rain was determined by measuring the residual concentrations after rainfall. Some samples were placed below a shield so as to eliminate the effects of splash and reveal the part played by runoff. Radiographic films were used to study the dispersion of labelled particles in the surrounding area. This radiographic method made it possible to determine the scale of erosion by splash for different rainfall conditions. The erosion diagrams obtained from these experiments show the correlations that exist between the intensity and duration of the rainfall and the erosion of the soil. Examination of the erosion diagrams and the shielded samples and analysis of the radiographs showed that erosion by rain on Kalahari ground covered with substeppe savannah is caused mainly by splash erosion and by dispersed, intermittent runoff. Sheet wash plays no part if the slope is less than 12 degrees. (author) [fr

  11. Wind erosion risk in the southwest of Buenos Aires Province, Argentina, and its relationship to the productivity index

    Science.gov (United States)

    Silenzi, Juan C.; Echeverría, Nora E.; Vallejos, Adrián G.; Bouza, Mariana E.; De Lucia, Martín P.

    2012-01-01

    Wind erosion risk (WER) for soils of each municipality in the southwest (SW) of Buenos Aires Province (10,491,172 ha) was determined using the wind erosion equation (WEQ) model. WER results from multiplying the soil erodibility index (" I") of the soil by the climatic factor ( C). WER (Mg ha -1 year -1) of each municipality was: Bahía Blanca: 22.4, Coronel Dorrego: 18.6, Coronel Pringles: 4.5, Coronel Rosales: 48.2, Coronel Suárez: 4.5, Guaminí: 3.0, Patagones: 104.6, Puan: 12.2, Saavedra: 3.0, Tornquist: 6.8, and Villarino: 31.7. The maximum weighted average of " I" (Mg ha -1 year -1) corresponded to Coronel Rosales (87.6), Patagones (87.2), Villarino (85.7), Puan (67.9); Guaminí (59.6), Coronel Dorrego (53.1), and Bahía Blanca (39.3); the remaining municipalities ranged between 34.9 and 32.1 Mg ha -1 year -1. The highest C (%) corresponded to Patagones (120), Bahía Blanca (57), Coronel Rosales (55), Villarino (37), Coronel Dorrego (35), Tornquist (21), and Puan (18); for the remaining municipalities it was 14%. The productivity index (PI) is known to establish a numerical value of the productive capacity of lands. The relationship between WER and PI, weighted averages, in all the studied municipalities was fitted by means of a linear model, WER (Mg ha -1 year -1) = 95.23 - 2.09 * PI (%) ( R2 = 66%), and a second-order polynomial model, WER (Mg ha -1 year -1) = 139.41 - 5.86 * PI (%) + 0.07 * PI 2 (%) ( R2 = 74%). No statistically significant relationship was found between WER and PI for each municipality.

  12. Development of Methodology to Classify Historical Panchromatic Aerial Photography. Analysis of Landscape Features on Point Au Fer Island, Louisiana - from 1956 to 2009: A Case Study

    Science.gov (United States)

    2011-12-01

    7,386 acres). Hurricanes and other extreme extratropical storms have been shown to contribute to extensive shoreline erosion and breaching, and the...that provide protection from storms ; serve as species habitat; act as a control for nutrient and pollution transfer; support fish, agriculture...quickly and accurately classify historical panchromatic photography in order to identify storm -induced land loss and impacts (Morton et al. 2005; Barras

  13. Rainfall erosivity factor estimation in Republic of Moldova

    Science.gov (United States)

    Castraveš, Tudor; Kuhn, Nikolaus

    2017-04-01

    Rainfall erosivity represents a measure of the erosive force of rainfall. Typically, it is expressed as variable such as the R factor in the Universal Soil Loss Equation (USLE) (Wischmeier and Smith, 1965, 1978) or its derivates. The rainfall erosivity index for a rainfall event (EI30) is calculated from the total kinetic energy and maximum 30 minutes intensity of individual events. However, these data are often unavailable for wide regions and countries. Usually, there are three issues regarding precipitation data: low temporal resolution, low spatial density and limited access to the data. This is especially true for some of postsoviet countries from Eastern Europe, such as Republic of Moldova, where soil erosion is a real and persistent problem (Summer, 2003) and where soils represents the main natural resource of the country. Consequently, researching and managing soil erosion is particularly important. The purpose of this study is to develop a model based on commonly available rainfall data, such as event, daily or monthly amounts, to calculate rainfall erosivity for the territory of Republic of Moldova. Rainfall data collected during 1994-2015 period at 15 meteorological stations in the Republic of Moldova, with 10 minutes temporal resolution, were used to develop and calibrate a model to generate an erosivity map of Moldova. References 1. Summer, W., (2003). Soil erosion in the Republic of Moldova — the importance of institutional arrangements. Erosion Prediction in Ungauged Basins: Integrating Methods and Techniques (Proceedings of symposium HS01 held during IUGG2003 at Sapporo. July 2003). IAHS Publ. no. 279. 2. Wischmeier, W.H., and Smith, D.D. (1965). Predicting rainfall-erosion losses from cropland east of the Rocky Mountains. Agr. Handbook No. 282, U.S. Dept. Agr., Washington, DC 3. Wischmeier, W.H., and Smith, D.D. (1978). Predicting rainfall erosion losses. Agr. handbook No. 537, U.S. Dept. of Agr., Science and Education Administration.

  14. Restorative Management of Intrinsic and Extrinsic Dental Erosion.

    Science.gov (United States)

    Al-Salehi, Samira Kathryn

    2014-12-01

    The restorative management of tooth surface loss is highlighted through the presentation of two advanced cases of dental erosion. On presentation, the causes of the dental erosion in both patients had been previously diagnosed and stopped. The first patient was a 67 year old with intrinsic erosion and an element of attrition where a multidisciplinary approach was used. The other, a 17 year old patient with extrinsic erosion managed via adhesive restorations. Adhesive techniques are a relatively simple, effective and conservative method for the treatment of dental erosion. The two treatment modalities (conventional versus contemporary) are compared and discussed.

  15. Regional soil erosion assessment based on a sample survey and geostatistics

    Directory of Open Access Journals (Sweden)

    S. Yin

    2018-03-01

    (SRTM digital elevation model (DEM data worsened the estimation when used as the covariates for the interpolation of soil loss. Due to the unavailability of a 1 : 10 000 topography map for the entire area in this study, the model assisted by the land use, R, and K factors, with a resolution of 250 m, was used to generate the regional assessment of the soil erosion for Shaanxi Province. It demonstrated that 54.3 % of total land in Shaanxi Province had annual soil loss equal to or greater than 5 t ha−1 yr−1. High (20–40 t ha−1 yr−1, severe (40–80 t ha−1 yr−1, and extreme ( >  80 t ha−1 yr−1 erosion occupied 14.0 % of the total land. The dry land and irrigated land, forest, shrubland, and grassland in Shaanxi Province had mean soil loss rates of 21.77, 3.51, 10.00, and 7.27 t ha−1 yr−1, respectively. Annual soil loss was about 207.3 Mt in Shaanxi Province, with 68.9 % of soil loss originating from the farmlands and grasslands in Yan'an and Yulin districts in the northern Loess Plateau region and Ankang and Hanzhong districts in the southern Qingba mountainous region. This methodology provides a more accurate regional soil erosion assessment and can help policymakers to take effective measures to mediate soil erosion risks.

  16. Effect of mouthrinses with different active agents in the prevention of initial dental erosion.

    Science.gov (United States)

    de Oliveira, Tatiane Alexandre; Scaramucci, Tais; Nogueira, Fernando Neves; Simões, Alyne; Sobral, Maria Angela Pita

    2015-01-01

    Hydrochloric acid (HCl) from the gastric juice is the only source of intrinsic acid, which can reach the oral cavity in cases of gastroesophageal reflux or chronic vomiting, enhancing the risk of dental erosion. Compare the effects of mouthrinses with different active agents in the prevention of initial dental erosion caused by HCl. Casein (CAS at 0.2%), sodium hexametaphosphate (HMP at 0.02%), titanium tetrafluoride (TiF4 at 0.34%), and stannous fluoride (SnF2 at 0.87%) were individually added to an experimental mouthrinse. The mouthrinse without additives was used as the negative control (C) and a commercially available mouthrinse for erosion (ELM-Elmex®) as the reference product. Enamel specimens were exposed to human saliva and randomly assigned to 6 experimental groups (n = 8). Specimens were submitted to erosion in HCl for 10 s, followed by to the experimental mouthrinses for 30 s, and artificial saliva for 60 min. This cycle was repeated 3 times. The total amounts of calcium and phosphorus released by the specimens in the 2nd and 3rd erosive challenges were evaluated by atomic emission spectrometry. Statistical analysis used Shapiro-Wilks and Hartley tests, followed by one-way ANOVA and Tukey tests. When compared with C, ELM and HMP presented significantly less calcium in solution, with no difference between them. All the groups showed similar and significantly less phosphorus than C, except CAS. HMP was the only agent that could match the protection against initial erosion of the commercially available mouthrinse in both analyses.

  17. Definition of tolerable soil erosion values

    Directory of Open Access Journals (Sweden)

    G. Sparovek

    1997-09-01

    Full Text Available Although the criteria for defining erosion tolerance are well established, the limits generally used are not consistent with natural, economical and technological conditions. Rates greater than soil formation can be accepted only until a minimum of soil depth is reached, provided that they are not associated with environmental hazard or productivity losses. A sequence of equations is presented to calculate erosion tolerance rates through time. The selection of equation parameters permits the definition of erosion tolerance rates in agreement with environmental, social and technical needs. The soil depth change that is related to irreversible soil degradation can be calculated. The definition of soil erosion tolerance according to these equations can be used as a guideline for sustainable land use planning and is compatible with expert systems.

  18. PROBLEMS OF SOIL PROTECTION FROM EROSION

    Directory of Open Access Journals (Sweden)

    M. Voloshuk

    2007-10-01

    Full Text Available In this article the problems of soil protection from erosion in Moldova are considered. The history (evolution of erosive processes is generalized, the first items of information on presence washed off soils are marked. Purposeful study of soil erosion, development of measures of struggle with it were begun in Moldova at the end of 40 years. In connection with transition to new economic methods of conducting economy (farmers, rent, privatization of land before pedologist, the experts of design organizations put forward the new requirements to study of erosive processes, development of soil protection, ecologo-adaptive systems of landscape agriculture. The tasks for improvement of a soil cover, restoration of fertility soil and their protection are put forward which are necessary for deciding in a near future.

  19. Dental erosion: understanding this pervasive condition.

    Science.gov (United States)

    Almeida e Silva, Júnio S; Baratieri, Luiz Narciso; Araujo, Edson; Widmer, Nicolas

    2011-08-01

    Dental erosion is a contemporary disease, mostly because of the change of the eating patterns that currently exist in society. It is a "silent" and multifactorial disease, and is highly influenced by habits and lifestyles. The prevalence of dental erosion has considerably increased, with this condition currently standing as a great challenge for the clinician, regarding the diagnosis, identification of the etiological factors, prevention, and execution of an adequate treatment. This article presents a dental erosion review and a case report of a restorative treatment of dental erosion lesions using a combination of bonded ceramic overlays to reestablish vertical dimension and composite resin to restore the worn palatal and incisal surfaces of the anterior upper teeth. Adequate function and esthetics can be achieved with this approach. © 2011 Wiley Periodicals, Inc.

  20. Dental erosion in groups of Yemeni children and adolescents and the modification of an erosion partial recording system.

    Science.gov (United States)

    Al-Ashtal, Amin; Johansson, Anders; Omar, Ridwaan; Johansson, Ann-Katrin

    2017-07-01

    The prevalence of dental erosion is rising especially among children and adolescents and its grading needs further investigation. To determine the prevalence and severity of dental erosion in groups of Yemeni children and adolescents, and to clinically compare an erosion partial recording system (EPRS) with a proposed modified-simplified version (EPRS-M). Of 6163 individuals aged 5-6, 13-14 and 18-19 years, 911 were randomly selected, of which 668 participated in the study. Dental erosion was graded using EPRS. EPRS-M was proposed, and its sensitivity and specificity was calculated in relation to EPRS. Prevalence of erosion extending into dentine on at least one tooth was 6.8% among 5- to 6-year-olds, 3.0% among 13- to 14-year-olds and 14.6% among 18- to 19-year olds. The highest prevalence was 19.2% among girls aged 18-19 years which was significantly higher than boys (10.4%) in the same age group (P = 0.044). Sensitivity and specificity for EPRS-M in relation to EPRS were 85.7% and 100% for primary teeth, and 84.1% and 100% for permanent teeth. Dental erosion was common among children and older teenagers and highest among older girls but less common among younger teenagers. The tested accuracy of EPRS-M qualifies it to be used as an initial quick detection tool in future dental erosion research. © 2016 The Authors. International Journal of Paediatric Dentistry published by BSPD, IAPD and John Wiley & Sons Ltd.

  1. Integrative Analysis of DCE-MRI and Gene Expression Profiles in Construction of a Gene Classifier for Assessment of Hypoxia-Related Risk of Chemoradiotherapy Failure in Cervical Cancer

    DEFF Research Database (Denmark)

    Fjeldbo, Christina S; Julin, Cathinka H; Lando, Malin

    2016-01-01

    platforms. The prognostic value was independent of existing clinical markers, regardless of clinical endpoints. CONCLUSIONS: A robust DCE-MRI-associated gene classifier has been constructed that may be used to achieve an early indication of patients' risk of hypoxia-related chemoradiotherapy failure.......PURPOSE: A 31-gene expression signature reflected in dynamic contrast enhanced (DCE)-MR images and correlated with hypoxia-related aggressiveness in cervical cancer was identified in previous work. We here aimed to construct a dichotomous classifier with key signature genes and a predefined...... as an indicator of hypoxia. RESULTS: Classifier candidates were constructed by integrative analysis of ABrix and gene expression profiles in the training cohort and evaluated by a leave-one-out cross-validation approach. On the basis of their ability to separate patients correctly according to hypoxia status, a 6...

  2. Erosion testing of hard materials and coatings

    Energy Technology Data Exchange (ETDEWEB)

    Hawk, Jeffrey A.

    2005-04-29

    Erosion is the process by which unconstrained particles, usually hard, impact a surface, creating damage that leads to material removal and component failure. These particles are usually very small and entrained in fluid of some type, typically air. The damage that occurs as a result of erosion depends on the size of the particles, their physical characteristics, the velocity of the particle/fluid stream, and their angle of impact on the surface of interest. This talk will discuss the basics of jet erosion testing of hard materials, composites and coatings. The standard test methods will be discussed as well as alternative approaches to determining the erosion rate of materials. The damage that occurs will be characterized in genera1 terms, and examples will be presented for the erosion behavior of hard materials and coatings (both thick and thin).

  3. Erosive Lichen Planus.

    Science.gov (United States)

    Mauskar, Melissa

    2017-09-01

    Lichen planus is an inflammatory mucocutaneous condition with a myriad of clinical manifestations. There are 3 forms of lichen planus that effect the vulva: papulosquamous, hypertrophic, and erosive. Erosive lichen planus can progress to vulvar scaring, vaginal stenosis, and squamous cell carcinoma; these long-term sequelae cause sexual distress, depression, and decreased quality of life for patients. Diagnosis is often delayed because of patient embarrassment or clinician misdiagnosis. Early recognition and treatment is essential to decreasing the morbidity of this condition. Multimodal treatment, along with a multidisciplinary approach, will improve outcomes and further clinical advances in studying this condition. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Evaluation of dental erosion prevalence and contributing factors in patients referring to yazd dental school in 2012-2013

    Directory of Open Access Journals (Sweden)

    Farnaz Farahat

    2016-03-01

    Full Text Available Background and Aims: Dental erosion refers to the loss of tooth structure by being scratched chemically without bacterial involvement which needs to care about due to its prevalence and treatment problems. This study was designed with the aim of evaluation of the frequency of dental erosion and its causing factors in patients referring to yazd dental school in 2012-2013. Materials and Methods: In this cross-sectional study, 400 patients referring to yazd dental school were randomly selected. All of their teeth were evaluated in three surfaces (buccal, lingual and occlusal. The BEWE score was used for classification the extent of damages. Also, patients were given a questionnaire that included patient demographic information and questions to investigate the causes of dental erosion. Data were analyzed using SPSS version 17 and Mann-Whiney, Fisher exact, and Chi-square tests. Results: In this study, 138 men and 261 women were participated with the mean age of 33.26±10.83. 84 persons (21.1% had erosion. There was a direct and significant relationship between the dental erosion and patient's age (P >0.001. Also, there was a direct relationship between the dental erosion and reflux and consumption of lemon and pickle, beverages, soft beer and juice (P>0.001. Conclusion: Consumption of lemon and pickle, beverages, soft beer and juice increases the risk of erosion. Considering the prevalence of dental erosion in about 21% of patients, it is necessary to pay more attention to the knowledge of the causes of erosion and reduction strategies of it.

  5. Simwe model application on susceptibility analysis to linear erosion: a case study in Alto Douro wine region.

    Science.gov (United States)

    Fernandes, Joana; Bateira, Carlos; Soares, Laura; Faria, Ana; Moura, Rui; Gonçalves, José

    2016-04-01

    The wine production in Alto Douro Wine Region - one of the world's oldest regulated and demarcated wine region - is based on a slope system organized in agricultural terraces once supported exclusively by dry stone walls. It has been undergoing the necessary changes for the introduction of technological innovations partially associated to the mechanization of vineyards work. In this sense, different forms of terrain framing have been implemented, namely the substitution of stone walls by earth embankments. This evolution raises a group of problems related to the hydric soil erosion and landscape preservation, since Alto Douro Wine Region is classified as UNESCO World Heritage Site since 2001. The study area is mostly occupied by vineyards planted in the agriculture terraces without continuous vegetation, the flow proceeds superficially influenced by the weak infiltration capacity and hydraulic conductivity. So, because of this conditioning factor the erosive features present non-significant depth, and the length thereof is limited essentially by the slope of the land, where was registered 64 gullies and 78 rills This paper focuses on the evaluation of susceptibility to linear erosion, through the application of SIMWE (SIMulated Water Erosion), (Mitas and Mitasova, 1998), using a digital elevation model, with pixel of one square meter of spatial resolution, created through detail aerial photographs, (side pixel of 50 cm), submitted to automatic stereo-correlation procedures in Agisoft PhotoScan software. The results provided by the model are compared with hydrological characteristics of the soil, (infiltration capacity, and hydraulic conductivity), soil texture, and soil structure parameters (identified by electrical resistivity measurement) where obtained from field monitoring. This approach demonstrates an association between the spatial distribution of erosive features with high values of soil saturation, and reduced water discharge (10-110 cm3/s), that are

  6. Predicting soil erosion using Rusle and NDVI time series from TM Landsat 5

    Directory of Open Access Journals (Sweden)

    Daniel Fonseca de Carvalho

    2014-03-01

    Full Text Available The objective of this work was to evaluate the seasonal variation of soil cover and rainfall erosivity, and their influences on the revised universal soil loss equation (Rusle, in order to estimate watershed soil losses in a temporal scale. Twenty-two TM Landsat 5 images from 1986 to 2009 were used to estimate soil use and management factor (C factor. A corresponding rainfall erosivity factor (R factor was considered for each image, and the other factors were obtained using the standard Rusle method. Estimated soil losses were grouped into classes and ranged from 0.13 Mg ha-1 on May 24, 2009 (dry season to 62.0 Mg ha-1 on March 11, 2007 (rainy season. In these dates, maximum losses in the watershed were 2.2 and 781.5 Mg ha-1 , respectively. Mean annual soil loss in the watershed was 109.5 Mg ha-1 , but the central area, with a loss of nearly 300.0 Mg ha-1 , was characterized as a site of high water-erosion risk. The use of C factor obtained from remote sensing data, associated to corresponding R factor, was fundamental to evaluate the soil erosion estimated by the Rusle in different seasons, unlike of other studies which keep these factors constant throughout time.

  7. Evaluation of a chemical risk assessment method of South Korea for chemicals classified as carcinogenic, mutagenic or reprotoxic (CMR).

    Science.gov (United States)

    Kim, Min-Uk; Byeon, Sang-Hoon

    2017-12-12

    Chemicals were used in various fields by the development of industry and science and technology. The Chemical Hazard Risk Management (CHARM) was developed to assess the risk of chemicals in South Korea. In this study, we were to evaluate the CHARM model developed for the effective management of workplace chemicals. We used 59 carcinogenic, mutagenic or reprotoxic (CMR) materials, which are both the work environment measurement result and the usage information among the manufacturer data. The CHARM model determines the risk to human health using the exposure level (based on working environment measurements or a combination of the quantity used and chemical physical properties (e.g., fugacity and volatility)), hazard (using occupational exposure limit (OEL) or Risk phrases (R-phrases)/Hazard statements (H-statements) from the Material Safety Data Sheet (MSDS)). The risk level was lower when using the results of the work environment measurement than when applying the chemical quantity and physical properties in the exposure level evaluation method. It was evaluated as grade 4 for the CMR material in the hazard class determination. The risk assessment method by R-phrases was evaluated more conservatively than the risk assessment method by OEL. And the risk assessment method by H-statements was evaluated more conservatively than the risk assessment method by R-phrases. The CHARM model was gradually conservatively assessed as it proceeded in the next step without quantitative information for individual workplaces. The CHARM is expected to help identify the risk if the hazards and exposure levels of chemicals were identified in individual workplaces. For CMR substances, although CHARM is highly evaluated for hazards, the risk is assessed to be low if exposure levels are assessed low. When evaluating the risk of highly hazardous chemicals such as CMR substances, we believe the model should be adapted to be more conservative and classify these as higher risk. This work is

  8. The amount of glacial erosion of the bedrock

    International Nuclear Information System (INIS)

    Paasse, Tore

    2004-11-01

    The purpose of this study is to estimate an upper bound for the average erosion of fresh bedrock that can reasonably be expected during a glacial period or a single glaciation. The study is based on the assumption that classic sediments, formed by Scandinavian ice erosion during the Quaternary period, still exist within the formerly glaciated area or its periphery. The volume of these sediments thus constitutes the maximum average glacial erosion of bedrock within this area. This volume is calculated by estimating the thickness of the minerogenic Quaternary from well data in Sweden and Denmark and from seismic measurements in adjacent sea areas. The average thickness of the Quaternary deposits and other reogolith in the investigated area was estimated to 16 m. Assuming that the whole volume is the result of glacial erosion of fresh bedrock this corresponds to 12 m depth. However, a great part of the sediments may consist of glacially redistributed Tertiary regolith. As the amount of Tertiary regolith is uncertain the estimated maximum average glacial erosion rate in fresh bedrock is uncertain, and assuming that the total sediment volume is the result of glacial erosion leads to an overestimation of the glacial erosion depth. Considering this, the average glacial erosion during a full glacial period has been estimated to between 0.2 m and 4 m. If the extremes in the made assumptions are excluded the glacial erosion during a glacial cycle can be estimated to about 1 m

  9. The amount of glacial erosion of the bedrock

    Energy Technology Data Exchange (ETDEWEB)

    Paasse, Tore [Geological Survey of Sweden, Uppsala (Sweden)

    2004-11-01

    The purpose of this study is to estimate an upper bound for the average erosion of fresh bedrock that can reasonably be expected during a glacial period or a single glaciation. The study is based on the assumption that classic sediments, formed by Scandinavian ice erosion during the Quaternary period, still exist within the formerly glaciated area or its periphery. The volume of these sediments thus constitutes the maximum average glacial erosion of bedrock within this area. This volume is calculated by estimating the thickness of the minerogenic Quaternary from well data in Sweden and Denmark and from seismic measurements in adjacent sea areas. The average thickness of the Quaternary deposits and other reogolith in the investigated area was estimated to 16 m. Assuming that the whole volume is the result of glacial erosion of fresh bedrock this corresponds to 12 m depth. However, a great part of the sediments may consist of glacially redistributed Tertiary regolith. As the amount of Tertiary regolith is uncertain the estimated maximum average glacial erosion rate in fresh bedrock is uncertain, and assuming that the total sediment volume is the result of glacial erosion leads to an overestimation of the glacial erosion depth. Considering this, the average glacial erosion during a full glacial period has been estimated to between 0.2 m and 4 m. If the extremes in the made assumptions are excluded the glacial erosion during a glacial cycle can be estimated to about 1 m.

  10. Photogrammetric techniques for across-scale soil erosion assessment

    OpenAIRE

    Eltner, Anette

    2016-01-01

    Soil erosion is a complex geomorphological process with varying influences of different impacts at different spatio-temporal scales. To date, measurement of soil erosion is predominantly realisable at specific scales, thereby detecting separate processes, e.g. interrill erosion contrary to rill erosion. It is difficult to survey soil surface changes at larger areal coverage such as field scale with high spatial resolution. Either net changes at the system outlet or remaining traces after the ...

  11. Effects of erosive, cariogenic or combined erosive/cariogenic challenges on human enamel: an in situ/ex vivo study.

    Science.gov (United States)

    Honório, H M; Rios, D; Santos, C F; Magalhães, A C; Buzalaf, M A R; Machado, M A A M

    2008-01-01

    Individuals with cariogenic diet can also consume erosive beverages. Thus, it seems necessary to investigate a possible caries/erosion interaction. To test in situ/ex vivo a combination of these challenges, 11 subjects wore intraoral appliances containing four enamel blocks randomly assigned. In the first 2-week phase, the appliances were immersed in a cola drink 3 times/day. Two blocks were free of plaque (erosion only: EO) and two blocks were covered with plaque (erosion + plaque: EP). In the second 2-week phase, four new blocks were all covered with plaque and subjected to a sucrose solution 8 times/day. Among the four new blocks, two were also subjected to the cola drink 3 times/day (erosion + caries: EC) while the other two were not (caries only: CO). Thus, in EO, the specimens were fixed at the intraoral appliance level. In EP, EC and CO they were fixed 1.0 mm under the appliance level and covered with plastic meshes for dental plaque accumulation. Changes in wear and hardness were measured. Data were tested using ANOVA and Tukey's test (p cariogenic challenges showed less enamel alterations when compared to erosive or cariogenic challenges only. (c) 2008 S. Karger AG, Basel.

  12. Soil erosion assessment - Mind the gap

    Science.gov (United States)

    Kim, Jongho; Ivanov, Valeriy Y.; Fatichi, Simone

    2016-12-01

    Accurate assessment of erosion rates remains an elusive problem because soil loss is strongly nonunique with respect to the main drivers. In addressing the mechanistic causes of erosion responses, we discriminate between macroscale effects of external factors - long studied and referred to as "geomorphic external variability", and microscale effects, introduced as "geomorphic internal variability." The latter source of erosion variations represents the knowledge gap, an overlooked but vital element of geomorphic response, significantly impacting the low predictability skill of deterministic models at field-catchment scales. This is corroborated with experiments using a comprehensive physical model that dynamically updates the soil mass and particle composition. As complete knowledge of microscale conditions for arbitrary location and time is infeasible, we propose that new predictive frameworks of soil erosion should embed stochastic components in deterministic assessments of external and internal types of geomorphic variability.

  13. Erosion of Earthen Levees by Wave Action

    Science.gov (United States)

    Ozeren, Y.; Wren, D. G.; Reba, M. L.

    2016-02-01

    Earthen levees of aquaculture and irrigation reservoirs in the United States often experience significant erosion due to wind-generated waves. Typically constructed using local soils, unprotected levees are subjected to rapid erosion and retreat due to wind generated waves and surface runoff. Only a limited amount of published work addresses the erosion rates for unprotected levees, and producers who rely on irrigation reservoirs need an economic basis for selecting a protection method for vulnerable levees. This, in turn, means that a relationship between wave energy and erosion of cohesive soils is needed. In this study, laboratory experiments were carried out in order to quantify wave induced levee erosion and retreat. A model erodible bank was packed using a soil consisting of approximately 14% sand, 73% silt, and 13% clay in a 20.6 m long 0.7 m wide and 1.2 m deep wave tank at the USDA-ARS, National Sedimentation Laboratory in Oxford MS. The geometry of the levee face was monitored by digital camera and the waves were measured by means of 6 capacitance wave staffs. Relationships were established between levee erosion, edge and retreat rates, and incident wave energy.

  14. Reduction of surface erosion in fusion reactors

    International Nuclear Information System (INIS)

    Rossing, T.D.; Das, S.K.; Kaminsky, M.

    1976-01-01

    Some of the major processes leading to surface erosion in fusion reactors are reviewed briefly, including blistering by implanted gas, sputtering by ions, atoms, and neutrons, and vaporization by local heating. Surface erosion affects the structural integrity and limits the lifetime of reactor components exposed to plasma radiation. In addition, some of the processes leading to surface erosion also cause the release of plasma contaminants. Methods proposed to reduce surface erosion have included control of surface temperature, selection of materials with a favorable microstructure, chemical and mechanical treatment of surfaces, and employment of protective surface coatings, wall liners, and divertors. The advantages and disadvantages of some of these methods are discussed

  15. Soil carbon and nitrogen erosion in forested catchments: implications for erosion-induced terrestrial carbon sequestration

    Science.gov (United States)

    E. M. Stacy; S. C. Hart; C. T. Hunsaker; D. W. Johnson; A. A. Berhe

    2015-01-01

    Lateral movement of organic matter (OM) due to erosion is now considered an important flux term in terrestrial carbon (C) and nitrogen (N) budgets, yet most published studies on the role of erosion focus on agricultural or grassland ecosystems. To date, little information is available on the rate and nature of OM eroded from forest ecosystems. We present annual...

  16. Soil erosion as a driver of land-use change

    NARCIS (Netherlands)

    Bakker, M.M.; Govers, G.; Kosmas, C.; VanAcker, H.; Oost, van K.; Rounsevell, M.

    2005-01-01

    Although much research has been carried out on the crop productivity response to soil erosion, little is known about the role of soil erosion as a driver of land-use change. Given, however, the some-times large erosion-induced reductions in crop yields, it appears likely that erosion has a strong

  17. Long-term predictive capability of erosion models

    Science.gov (United States)

    Veerabhadra, P.; Buckley, D. H.

    1983-01-01

    A brief overview of long-term cavitation and liquid impingement erosion and modeling methods proposed by different investigators, including the curve-fit approach is presented. A table was prepared to highlight the number of variables necessary for each model in order to compute the erosion-versus-time curves. A power law relation based on the average erosion rate is suggested which may solve several modeling problems.

  18. Erosion and corrosion of nuclear power plant materials

    International Nuclear Information System (INIS)

    1994-01-01

    This conference is composed of 23 papers, grouped in 3 sessions which main themes are: analysis of corrosion and erosion damages of nuclear power plant equipment and influence of water chemistry, temperature, irradiations, metallurgical and electrochemical factors, flow assisted cracking, stress cracking; monitoring and control of erosion and corrosion in nuclear power plants; susceptibility of structural materials to erosion and corrosion and ways to improve the resistance of materials, steels, coatings, etc. to erosion, corrosion and cracking

  19. Comparison Between Bandage Contact Lenses and Pressure Patching on the Erosion Area and Pain Scale in Patients With Corneal Erosion.

    Science.gov (United States)

    Triharpini, Ni Nyoman; Gede Jayanegara, I Wayan; Handayani, Ariesanti Tri; Widiana, I Gde Raka

    2015-01-01

    Corneal erosion is common in eye emergency cases. Extensive corneal erosions result in severe pain and prolonged healing time. This study aimed to compare bandage contact lenses with pressure patching in terms of reducing the size of the erosion area, pain scale in patients with corneal erosion and its complications. A randomized open-label clinical trial was conducted. Subjects with mechanical corneal erosion were selected to use either bandage contact lenses or pressure patching. All subjects received antibiotic eye drops and 0.5% tropicamide eye drops. Evaluations were done 24 and 72 hours after treatment. The size of the corneal erosion area, pain scale, and complications were assessed. A total of 32 eyes (16 eyes in each group) were studied. The change in the size of the corneal erosion area was greater in the bandage contact lens group than in the pressure patching group, although there was no significant difference. In the bandage contact lens group, 56.25% of the eyes were healed at 24 hours and 43.75% were healed at 72 hours. In the pressure patching group, 62.50% were healed at 24 hours and 12.50% were healed at 72 hours. The change in pain scale was significantly greater in the bandage contact lens group than in the pressure patching group. No complications were found in both groups. Bandage contact lenses are an effective alternative to treating mechanical corneal erosion because of their effect in reducing pain without causing any complications.

  20. Water Impingement Erosion of Deep-Rolled Ti64

    Directory of Open Access Journals (Sweden)

    Dina Ma

    2015-08-01

    Full Text Available In this work, the Liquid Impingement Erosion (LIE performances of deep-rolling (DR treated and non-treated Ti64 were investigated. Various erosion stages, from the incubation to the terminal erosion stages, could be observed. A full factorial design of experiments was used to study the effect of DR process parameters (Feed Rate, Spindle Velocity, Number of Passes, Pressure on the residual stress distribution, microhardness and surface roughness of the treated Ti64 specimens. The DR-treated Ti64 specimens exhibited improved surface microhardness, surface roughness, and large magnitude of compressive residual stresses, which were attributed to the amount of cold work induced by the DR process. Although DR improved the mechanical properties of the Ti64, the results showed that the treatment has little or no effect on the LIE performance of Ti64 but different damage modes were observed in these two cases. Evolution of the erosion stages was described based on water-hammer pressure, stress waves, radial wall jetting, and hydraulic penetration modes. The initial erosion stages were mainly influenced by water-hammer pressure and stress waves, whereas the intermediate erosion stages were influenced by the combination of the four modes together. The final erosion stages contain the four modes, however the erosion was greatly driven by the radial jetting and hydraulic penetration modes, where more material was removed. The failure mechanism of the final stages of the LIE test of both DR-treated and non-treated Ti64 was characterized as fatigue fracture. However, a brittle fracture behavior was observed in the initial and intermediate erosion stages of the DR-treated Ti64, whereas a ductile fracture behavior was observed in the non-treated Ti64. This was concluded from the micrographs of the LIE damage through different erosion stages.

  1. Understanding Soil Erosion in Irrigated Agriculture

    OpenAIRE

    O' Schwankl, Lawrence J

    2006-01-01

    A soil's physical and chemical properties determine whether it is vulnerable to erosion, which can reduce soil quality and cause other problems besides. Learn the basics of identifying what type of erosion is affecting your land and what's causing it.

  2. Erosion and the limits to planetesimal growth

    Science.gov (United States)

    Krijt, S.; Ormel, C. W.; Dominik, C.; Tielens, A. G. G. M.

    2015-02-01

    Context. The coagulation of microscopic dust into planetesimals is the first step towards the formation of planets. The composition, size, and shape of the growing aggregates determine the efficiency of this early growth. In particular, it has been proposed that fluffy ice aggregates can grow very efficiently in protoplanetary disks, suffering less from the bouncing and radial drift barriers. Aims: While the collision velocity between icy aggregates of similar size is thought to stay below the fragmentation threshold, they may nonetheless lose mass from collisions with much smaller projectiles. As a result, erosive collisions have the potential to terminate the growth of pre-planetesimal bodies. We investigate the effect of these erosive collisions on the ability of porous ice aggregates to cross the radial drift barrier. Methods: We develop a Monte Carlo code that calculates the evolution of the masses and porosities of growing aggregates, while resolving the entire mass distribution at all times. The aggregate's porosity is treated independently of its mass, and is determined by collisional compaction, gas compaction, and eventually self-gravity compaction. We include erosive collisions and study the effect of the erosion threshold velocity on aggregate growth. Results: For erosion threshold velocities of 20-40 m s-1, high-velocity collisions with small projectiles prevent the largest aggregates from growing when they start to drift. In these cases, our local simulations result in a steady-state distribution, with most of the dust mass in particles with Stokes numbers close to unity. Only for the highest erosion threshold considered (60 m s-1) do porous aggregates manage to cross the radial drift barrier in the inner 10 AU of MMSN-like disks. Conclusions: Erosive collisions are more effective in limiting the growth than fragmentary collisions between similar-size particles. Conceivably, erosion limits the growth before the radial drift barrier, although the

  3. Identifying desertification risk areas using fuzzy membership and geospatial technique - A case study, Kota District, Rajasthan

    Science.gov (United States)

    Dasgupta, Arunima; Sastry, K. L. N.; Dhinwa, P. S.; Rathore, V. S.; Nathawat, M. S.

    2013-08-01

    Desertification risk assessment is important in order to take proper measures for its prevention. Present research intends to identify the areas under risk of desertification along with their severity in terms of degradation in natural parameters. An integrated model with fuzzy membership analysis, fuzzy rule-based inference system and geospatial techniques was adopted, including five specific natural parameters namely slope, soil pH, soil depth, soil texture and NDVI. Individual parameters were classified according to their deviation from mean. Membership of each individual values to be in a certain class was derived using the normal probability density function of that class. Thus if a single class of a single parameter is with mean μ and standard deviation σ, the values falling beyond μ + 2 σ and μ - 2 σ are not representing that class, but a transitional zone between two subsequent classes. These are the most important areas in terms of degradation, as they have the lowest probability to be in a certain class, hence highest probability to be extended or narrowed down in next or previous class respectively. Eventually, these are the values which can be easily altered, under extrogenic influences, hence are identified as risk areas. The overall desertification risk is derived by incorporating the different risk severity of each parameter using fuzzy rule-based interference system in GIS environment. Multicriteria based geo-statistics are applied to locate the areas under different severity of desertification risk. The study revealed that in Kota, various anthropogenic pressures are accelerating land deterioration, coupled with natural erosive forces. Four major sources of desertification in Kota are, namely Gully and Ravine erosion, inappropriate mining practices, growing urbanization and random deforestation.

  4. Soft drinks and in vitro dental erosion.

    Science.gov (United States)

    Gravelle, Brent L; Hagen Ii, Ted W; Mayhew, Susan L; Crumpton, Brooks; Sanders, Tyler; Horne, Victoria

    2015-01-01

    The purpose of this investigation was to determine to what extent the in vitro exposure of healthy teeth to various commonly consumed carbonated soft drinks may precipitate dental erosion. Forty-two healthy, extracted, previously unerupted human molars were weighed prior to, during, and after suspension in various sugared and diet or zero-calorie carbonated beverages for 20 days; the specimens were stored at room temperature while being stirred at 275 rpm. The percentage decrease in tooth weight from before to after exposure represented the weight loss due to enamel erosion; values in the experimental groups varied from 3.22% to 44.52% after 20 days' exposure. Data were subjected to analysis of variance and post hoc Scheffe testing at a level of α = 0.05. Nonsugared drinks (diet and zero-calorie) as a whole were more erosive than sugared beverages. A significant positive correlation was found between the amount of titratable acid and percentage of tooth erosion, while a significant negative correlation was revealed between the beverage pH and percentage of tooth erosion. No significant correlations were found between calcium or phosphate ion concentrations and the amount of erosion. It appears that enamel erosion is dependent on not only the beverage flow rate, pH, and amount of titratable acid, but also whether the soft drink is of the diet or zero-calorie variety, which reflects the type of artificial sweetener present.

  5. Acoustic measurements of soil-pipeflow and internal erosion

    Science.gov (United States)

    Internal erosion of soil pipes can lead to embankment failures, landslides, and gully erosion. Therefore, non-intrusive methods are needed to detect and monitor soil pipeflow and the resulting internal erosion. This paper presents a laboratory study using both active and passive acoustic techniques ...

  6. Conjunctival erosion after glaucoma drainage device surgery: A feasible option

    OpenAIRE

    Dubey, Suneeta; Prasanth, Baswati; Acharya, Manisha C; Narula, Ritesh

    2013-01-01

    Glaucoma drainage devices (GDDs) have been used in the management of complicated glaucomas. GDDs are associated with various complications such as tube migration, tube or plate exposure or extrusion, ocular motility disturbance and infection. Erosion of conjunctiva and exposure of the GDD remains a risk factor for the development of endophthalmitis. A wide range of materials have been used for this purpose, including sclera, dura, pericardium, fascia lata and cornea. However, there is no evid...

  7. Dental erosion: prevalence, incidence, and distribution

    NARCIS (Netherlands)

    Jager, D.H.J.; Amaechi, B.T.

    2015-01-01

    Dental erosion is one of the most common dental diseases and it is a growing problem. Numerous epidemiological studies have investigated the prevalence of dental erosion. For these studies different cross sections of the population are investigated. Large differences were found between countries,

  8. Natural and anthropogenic rates of soil erosion

    Directory of Open Access Journals (Sweden)

    Mark A. Nearing

    2017-06-01

    Full Text Available Regions of land that are brought into crop production from native vegetation typically undergo a period of soil erosion instability, and long term erosion rates are greater than for natural lands as long as the land continues being used for crop production. Average rates of soil erosion under natural, non-cropped conditions have been documented to be less than 2 Mg ha−1 yr−1. On-site rates of erosion of lands under cultivation over large cropland areas, such as in the United States, have been documented to be on the order of 6 Mg ha−1 yr−1 or more. In northeastern China, lands that were brought into production during the last century are thought to have average rates of erosion over this large area of as much as 15 Mg ha−1 yr−1 or more. Broadly applied soil conservation practices, and in particular conservation tillage and no-till cropping, have been found to be effective in reducing rates of erosion, as was seen in the United States when the average rates of erosion on cropped lands decreased from on the order of 9 Mg ha−1 yr−1 to 6 or 7 Mg ha−1 yr−1 between 1982 and 2002, coincident with the widespread adoption of new conservation tillage and residue management practices. Taking cropped lands out of production and restoring them to perennial plant cover, as was done in areas of the United States under the Conservation Reserve Program, is thought to reduce average erosion rates to approximately 1 Mg ha−1 yr−1 or less on those lands.

  9. Cesium-137, a tool for the assessment and the management of erosion risks

    International Nuclear Information System (INIS)

    Bernard, C.; Mabit, L.; Laverdière, M.R.; Wicherek, S.

    1998-01-01

    Cesium-137 (137Cs) is a radioisotope that was artificially introduced in the environment through the extensive high-atmosphere bomb tests that took place in the 1950s and 1960s. Due to its environmental behavior in soils, this isotope is a particularly interesting soil movement indicator. Its spatial redistribution reveals global soil movements that were initiated some 35 years ago. The rates and spatial extent of soil loss and deposition areas can be established, and thus soil movement budgets are easily estimated, at scales ranging from small plots to watersheds. Generally, soil movements are estimated by comparing the activity of 137Cs (expressed in Bq.m-2) of cultivated soils to that of so-called reference sites (old prairie or forest soils) assumed to be uneroded. Different models to translate soil 137Cs variations into soil movements have been suggested over the years (equations 3 to 5). The authors used this technique in Quebec and France. The sampling of 63 cultivated fields near Quebec City, led to an average soil loss estimate of nearly 6 Mg.ha-1.yr-1. The erosion rates varied according the land use and slope steepness (Table 2). The results of this study also suggest that redeposition is an important component of the overall erosive process, particularly under low grade slopes and protective plant cover conditions. From 137Cs measurements obtained on a 180 ha unit watershed near Vierzy (France), it was estimated that 45% and 14% of the watershed area had experienced a net soil loss and gain respectively (Figure 4). The net sediment output was evaluated at less than 1.9 Mg.ha-1.yr-1. In a still on-going study, 137Cs is used to shed some light on the origins of the sedimentation problem impairing the waters of Boyer River (Québec). Soils from cultivated fields, stream bank soils and sediments from the river bed are counted for 137Cs. It was estimated that 78% of the counted bottom sediments originated from cultivated fields, while the other 22% was from

  10. Advancements in Hydrology and Erosion Process Understanding and Post-Fire Hydrologic and Erosion Model Development for Semi-Arid Landscapes

    Science.gov (United States)

    Williams, C. Jason; Pierson, Frederick B.; Al-Hamdan, Osama Z.; Robichaud, Peter R.; Nearing, Mark A.; Hernandez, Mariano; Weltz, Mark A.; Spaeth, Kenneth E.; Goodrich, David C.

    2017-04-01

    Fire activity continues to increase in semi-arid regions around the globe. Private and governmental land management entities are challenged with predicting and mitigating post-fire hydrologic and erosion responses on these landscapes. For more than a decade, a team of scientists with the US Department of Agriculture has collaborated on extensive post-fire hydrologic field research and the application of field research to development of post-fire hydrology and erosion predictive technologies. Experiments funded through this research investigated the impacts of fire on vegetation and soils and the effects of these fire-induced changes on infiltration, runoff generation, erodibility, and soil erosion processes. The distribution of study sites spans diverse topography across grassland, shrubland, and woodland landscapes throughout the western United States. Knowledge gleaned from the extensive field experiments was applied to develop and enhance physically-based models for hillslope- to watershed-scale runoff and erosion prediction. Our field research and subsequent data syntheses have identified key knowledge gaps and challenges regarding post-fire hydrology and erosion modeling. Our presentation details some consistent trends across a diverse domain and varying landscape conditions based on our extensive field campaigns. We demonstrate how field data have advanced our understanding of post-fire hydrology and erosion for semi-arid landscapes and highlight remaining key knowledge gaps. Lastly, we briefly show how our well-replicated experimental methodologies have contributed to advancements in hydrologic and erosion model development for the post-fire environment.

  11. Effect of mouthrinses with different active agents in the prevention of initial dental erosion

    Directory of Open Access Journals (Sweden)

    Tatiane Alexandre de Oliveira

    2015-01-01

    Full Text Available Introduction: Hydrochloric acid (HCl from the gastric juice is the only source of intrinsic acid, which can reach the oral cavity in cases of gastroesophageal reflux or chronic vomiting, enhancing the risk of dental erosion. Aim: Compare the effects of mouthrinses with different active agents in the prevention of initial dental erosion caused by HCl. Subjects and Methods: Casein (CAS at 0.2%, sodium hexametaphosphate (HMP at 0.02%, titanium tetrafluoride (TiF 4 at 0.34%, and stannous fluoride (SnF 2 at 0.87% were individually added to an experimental mouthrinse. The mouthrinse without additives was used as the negative control (C and a commercially available mouthrinse for erosion (ELM - Elmex ® as the reference product. Enamel specimens were exposed to human saliva and randomly assigned to 6 experimental groups (n = 8. Specimens were submitted to erosion in HCl for 10 s, followed by to the experimental mouthrinses for 30 s, and artificial saliva for 60 min. This cycle was repeated 3 times. The total amounts of calcium and phosphorus released by the specimens in the 2 nd and 3 rd erosive challenges were evaluated by atomic emission spectrometry. Statistical analysis used Shapiro-Wilks and Hartley tests, followed by one-way ANOVA and Tukey tests. Results: When compared with C, ELM and HMP presented significantly less calcium in solution, with no difference between them. All the groups showed similar and significantly less phosphorus than C, except CAS. Conclusions: HMP was the only agent that could match the protection against initial erosion of the commercially available mouthrinse in both analyses.

  12. Development of an Integrated Water and Wind Erosion Model

    Science.gov (United States)

    Flanagan, D. C.; Ascough, J. C.; Wagner, L. E.; Geter, W. F.

    2006-12-01

    Prediction technologies for soil erosion by the forces of wind or water have largely been developed independently from one another, especially within the United States. Much of this has been due to the initial creation of equations and models which were empirical in nature (i.e., Universal Soil Loss Equation, Wind Erosion Equation) and based upon separate water erosion or wind erosion plot and field measurements. Additionally, institutional organizations in place typically divided research efforts and funding to unique wind or water erosion research and modeling projects. However, during the past 20 years computer technologies and erosion modeling have progressed to the point where it is now possible to merge physical process-based computer simulation models into an integrated water and wind erosion prediction system. In a physically- based model, many of the processes which must be simulated for wind and water erosion computations are the same, e.g., climate, water balance, runoff, plant growth, etc. Model components which specifically deal with the wind or water detachment, transport and deposition processes are those that must differ, as well as any necessary parameterization of input variables (e.g., adjusted soil erodibilities, critical shear stresses, etc.) for those components. This presentation describes current efforts towards development of a combined wind and water erosion model, based in part upon technologies present in the Water Erosion Prediction Project (WEPP) and the Wind Erosion Prediction System (WEPS) models. Initial efforts during the past two years have resulted in modular modeling components that allow for prediction of infiltration, surface runoff, and water erosion at a hillslope scale within an Object Modeling System. Additional components currently in development include wind detachment at a single field point, continuous water balance, and unified plant growth. Challenges in this project are many, and include adequate field

  13. Erosion scenarios for Wellenberg

    International Nuclear Information System (INIS)

    Klemenz, W.

    1993-09-01

    The proposed Wellenberg site for a radioactive waste repository is located between Altzellen in the Engelberger valley and the Oberrickenbach valley, in a thick Valanginian marl series. The marl is generally overlaid with unconsolidated rocks but reaches to the surface in some places. In contrast to the situation in the Oberbauenstock region this marl complex is not protected by an overlying erosion resistant series and exhibits a marked relief. The question therefore arises with respect to the Wellenberg site, to what extent will the marl (i.e. the repository host rock formation) be removed by erosion processes during the 100,000 years interval under consideration and what overburden will remain at the end of this period. This report presents the results of an investigation of the longterm behaviour of the proposed site in respect of those processes of erosion and deposition which can lead to changes in the terrain surface and its location relative to the repository. A wide range of possible scenarios encompassing different developments of climatic conditions during the 100,000 year period of interest, was investigated. In addition to the continuation of the present climate and the occurrence of a new ice age on the scale of the Wuerm glaciation the consequences of altered climatic conditions on erosion removal of the repository overburden were considered. Within the 100,000 year period of interest none of the scenarios considered leads to the exposure of the repository. (author) figs., tabs, refs

  14. Combining Landsat TM multispectral satellite imagery and different modelling approaches for mapping post-fire erosion changes in a Mediterranean site

    Science.gov (United States)

    Petropoulos, George P.; Kairis, Orestis; Karamesouti, Mina; Papanikolaou, Ioannis D.; Kosmas, Constantinos

    2013-04-01

    South European countries are naturally vulnerable to wildfires. Their natural resources such as soil, vegetation and water may be severely affected by wildfires, causing an imminent environmental deterioration due to the complex interdependence among biophysical components. Soil surface water erosion is a natural process essential for soil formation that is affected by such interdependences. Accelerated erosion due to wildfires, constitutes a major restrictive factor for ecosystem sustainability. In 2007, South European countries were severely affected by wildfires, with more than 500,000 hectares of land burnt in that year alone, well above the average of the last 30 years. The present work examines the changes in spatial variability of soil erosion rates as a result of a wildfire event that took place in Greece in 2007, one of the most devastating years in terms of wildfire hazards. Regional estimates of soil erosion rates before and after the fire outbreak were derived from the Revised Universal Soil Loss Equation (RUSLE, Renard et al. 1991) and the Pan-European Soil Erosion Risk Assessment model (PESERA, Kirkby, 1999; Kirkby et al., 2000). Inputs for both models included climatic, land-use, soil type, topography and land use management data. Where appropriate, both models were also fed with input data derived from the analysis of LANDSAT TM satellite imagery available in our study area, acquired before and shortly after the fire suppression. Our study was compiled and performed in a GIS environment. In overall, the loss of vegetation from the fire outbreak caused a substantial increase of soil erosion rates in the affected area, particularly towards the steep slopes. Both tested models were compared to each other and noticeable differences were observed in the soil erosion predictions before and after the fire event. These are attributed to the different parameterization requirements of the 2 models. This quantification of sediment supply through the river

  15. A longitudinal study of tooth erosion in adolescents.

    NARCIS (Netherlands)

    El Aidi, H.; Bronkhorst, E.M.; Truin, G.J.

    2008-01-01

    Incidence studies on tooth erosion among adolescents are scarce. This longitudinal study aimed at estimating the prevalence, incidence, progression, and distribution of erosion in young adolescents over a 1.5-year period. Erosion at baseline was present in 32.2% of the 622 children (mean age, 11.9

  16. Assessment of soil erosion sensitivity and post-timber-harvesting erosion response in a mountain environment of Central Italy

    Science.gov (United States)

    Borrelli, Pasquale; Schütt, Brigitta

    2014-01-01

    This study aimed to assess the effects of forest management on the occurrence of accelerated soil erosion by water. The study site is located in a mountainous area of the Italian Central Apennines. Here, forest harvesting is a widespread forestry activity and is mainly performed on the moderate to steep slopes of the highlands. Through modeling operations based on data on soil properties and direct monitoring of changes in the post-forest-harvesting soil surface level at the hillslope scale, we show that the observed site became prone to soil erosion after human intervention. Indeed, the measured mean soil erosion rate of 49 t ha- 1 yr- 1 for the harvested watershed is about 21 times higher than the rate measured in its neighboring undisturbed forested watershed (2.3 t ha- 1 yr- 1). The erosive response is greatly aggravated by exposing the just-harvested forest, with very limited herbaceous plant cover, to the aggressive attack of the heaviest annual rainfall without adopting any conservation practices. The erosivity of the storms during the first four months of field measurements was 1571 MJ mm h- 1 ha- 1 in total (i.e., from September to December 2008). At the end of the experiment (16 months), 18.8%, 26.1% and 55.1% of the erosion monitoring sites in the harvested watershed recorded variations equal or greater than 0-5, 5-10 and > 10 mm, respectively. This study also provides a quantification of Italian forestland surfaces with the same pedo-lithological characteristics exploited for wood supply. Within a period of ten years (2002-2011), about 9891 ha of coppice forest changes were identified and their potential soil erosion rates modeled.

  17. How does slope form affect erosion in CATFLOW-SED?

    Science.gov (United States)

    Gabelmann, Petra; Wienhöfer, Jan; Zehe, Erwin

    2016-04-01

    Erosion is a severe environmental problem in agro-ecosystems with highly erodible loess soils. It is controlled by various factors, e.g. rainfall intensity, initial wetness conditions, soil type, land use and tillage practice. Furthermore slope form and gradient have been shown to influence erosion amounts to a large extent. Within the last fifty years, various erosion models have been developed to describe the erosion process, estimate erosion amounts and identify erosion-prone areas. These models differ in terms of complexity, the processes which are considered, and the data required for model calibration and they can be categorised into empirical or statistical, conceptual, and physically-based models. CATFLOW-SED is a process-based hydrology and erosion model that can operate on catchment and hillslope scales. Soil water dynamics are described by the Richards equation including effective approaches for preferential flow. Evapotranspiration is simulated using an approach based on the Penman-Monteith equation. The model simulates overland flow using the diffusion wave equation. Soil detachment is related to the attacking forces of rainfall and overland flow, and the erosion resistance of soil. Sediment transport capacity and sediment deposition are related to overland flow velocity using the equation of Engelund and Hansen and the sinking velocity of grain sizes respectively. We performed a study to analyse the erosion process on different virtual hillslopes, with varying slope gradient and slope form, using the CATFLOW-SED model. We explored the role of landform on erosion and sedimentation, particularly we look for forms that either maximise or minimise erosion. Results indicate the importance to performing the process implementation within physically meaningful limits and choose appropriate model parameters respectively.

  18. Gastroesophageal reflux is not associated with dental erosion in children.

    Science.gov (United States)

    Wild, Yvette K; Heyman, Melvin B; Vittinghoff, Eric; Dalal, Deepal H; Wojcicki, Janet M; Clark, Ann L; Rechmann, Beate; Rechmann, Peter

    2011-11-01

    Dental erosion is a complication of gastroesophageal reflux (GER) in adults; in children, it is not clear if GER has a role in dental pathologic conditions. Dietary intake, oral hygiene, high bacterial load, and decreased salivary flow might contribute independently to GER development or dental erosion, but their potential involvement in dental erosion from GER is not understood. We investigated the prevalence of dental erosion among children with and without GER symptoms, and whether salivary flow rate or bacterial load contribute to location-specific dental erosion. We performed a cross-sectional study of 59 children (ages, 9-17 y) with symptoms of GER and 20 asymptomatic children (controls); all completed a questionnaire on dietary exposure. Permanent teeth were examined for erosion into dentin, erosion locations, and affected surfaces. The dentist was not aware of GER status, and the gastroenterologist was not aware of dental status. Stimulated salivary flow was measured and salivary bacterial load was calculated for total bacteria, Streptococcus mutans, and Lactobacilli. Controlling for age, dietary intake, and oral hygiene, there was no association between GER symptoms and dental erosion by tooth location or affected surface. Salivary flow did not correlate with GER symptoms or erosion. Erosion location and surface were independent of total bacteria and levels of Streptococcus mutans and Lactobacilli. Location-specific dental erosion is not associated with GER, salivary flow, or bacterial load. Prospective studies are required to determine the pathogenesis of GER-associated dental erosion and the relationship between dental caries to GER and dental erosion. Copyright © 2011 AGA Institute. Published by Elsevier Inc. All rights reserved.

  19. Application of NAA in study of rill erosion process

    International Nuclear Information System (INIS)

    Li Mian; Li Zhanbin; Ding Wenfeng

    2003-01-01

    Based on the principle and method of rare earth elements (REE) tracer and NAA for the study of soil erosion, the changeable process of rill erosion on loess sloping surface was researched in runoff scouring experiments. The results showed that the REE tracer and NAA method can be used not only quantitatively to determine soil erosion amounts on different slope sections, but also to reveal the changeable trend of relative erosion amounts. The relative errors are mostly less than ±20% for the tracing elements, which is considered satisfactory in the soil erosion studies

  20. A linear relationship between wave power and erosion determines salt-marsh resilience to violent storms and hurricanes

    Science.gov (United States)

    Leonardi, Nicoletta; Ganju, Neil K.; Fagherazzi, Sergio

    2016-01-01

    Salt marsh losses have been documented worldwide because of land use change, wave erosion, and sea-level rise. It is still unclear how resistant salt marshes are to extreme storms and whether they can survive multiple events without collapsing. Based on a large dataset of salt marsh lateral erosion rates collected around the world, here, we determine the general response of salt marsh boundaries to wave action under normal and extreme weather conditions. As wave energy increases, salt marsh response to wind waves remains linear, and there is not a critical threshold in wave energy above which salt marsh erosion drastically accelerates. We apply our general formulation for salt marsh erosion to historical wave climates at eight salt marsh locations affected by hurricanes in the United States. Based on the analysis of two decades of data, we find that violent storms and hurricanes contribute less than 1% to long-term salt marsh erosion rates. In contrast, moderate storms with a return period of 2.5 mo are those causing the most salt marsh deterioration. Therefore, salt marshes seem more susceptible to variations in mean wave energy rather than changes in the extremes. The intrinsic resistance of salt marshes to violent storms and their predictable erosion rates during moderate events should be taken into account by coastal managers in restoration projects and risk management plans.

  1. A linear relationship between wave power and erosion determines salt-marsh resilience to violent storms and hurricanes.

    Science.gov (United States)

    Leonardi, Nicoletta; Ganju, Neil K; Fagherazzi, Sergio

    2016-01-05

    Salt marsh losses have been documented worldwide because of land use change, wave erosion, and sea-level rise. It is still unclear how resistant salt marshes are to extreme storms and whether they can survive multiple events without collapsing. Based on a large dataset of salt marsh lateral erosion rates collected around the world, here, we determine the general response of salt marsh boundaries to wave action under normal and extreme weather conditions. As wave energy increases, salt marsh response to wind waves remains linear, and there is not a critical threshold in wave energy above which salt marsh erosion drastically accelerates. We apply our general formulation for salt marsh erosion to historical wave climates at eight salt marsh locations affected by hurricanes in the United States. Based on the analysis of two decades of data, we find that violent storms and hurricanes contribute less than 1% to long-term salt marsh erosion rates. In contrast, moderate storms with a return period of 2.5 mo are those causing the most salt marsh deterioration. Therefore, salt marshes seem more susceptible to variations in mean wave energy rather than changes in the extremes. The intrinsic resistance of salt marshes to violent storms and their predictable erosion rates during moderate events should be taken into account by coastal managers in restoration projects and risk management plans.

  2. Illuminating wildfire erosion and deposition patterns with repeat terrestrial lidar

    Science.gov (United States)

    Rengers, Francis K.; Tucker, G.E.; Moody, J.A.; Ebel, Brian

    2016-01-01

    Erosion following a wildfire is much greater than background erosion in forests because of wildfire-induced changes to soil erodibility and water infiltration. While many previous studies have documented post-wildfire erosion with point and small plot-scale measurements, the spatial distribution of post-fire erosion patterns at the watershed scale remains largely unexplored. In this study lidar surveys were collected periodically in a small, first-order drainage basin over a period of 2 years following a wildfire. The study site was relatively steep with slopes ranging from 17° to > 30°. During the study period, several different types of rain storms occurred on the site including low-intensity frontal storms (2.4 mm h−1) and high-intensity convective thunderstorms (79 mm h−1). These storms were the dominant drivers of erosion. Erosion resulting from dry ravel and debris flows was notably absent at the site. Successive lidar surveys were subtracted from one another to obtain digital maps of topographic change between surveys. The results show an evolution in geomorphic response, such that the erosional response after rain storms was strongly influenced by the previous erosional events and pre-fire site morphology. Hillslope and channel roughness increased over time, and the watershed armored as coarse cobbles and boulders were exposed. The erosional response was spatially nonuniform; shallow erosion from hillslopes (87% of the study area) contributed 3 times more sediment volume than erosion from convergent areas (13% of the study area). However, the total normalized erosion depth (volume/area) was highest in convergent areas. From a detailed understanding of the spatial locations of erosion, we made inferences regarding the processes driving erosion. It appears that hillslope erosion is controlled by rain splash (for detachment) and overland flow (for transport and quasi-channelized erosion), with the sites of highest erosion corresponding to locations

  3. Adaptation to heavy rainfall events: watershed-community planning of soil and water conservation technologies in Syria

    Science.gov (United States)

    Ziadat, Feras; Al-Wadaey, Ahmed; Masri, Zuhair; Sakai, Hirokazu

    2010-05-01

    The Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) and other research, predict a significant future increase in the frequency and intensity of heavy rainfall events in many regions. This increase runoff and soil erosion, and reduce agricultural productivity, as well as increasing risks of flood damage to crops and infrastructure. Implementing adaptation measures and improved land management through erosion control and soil protection are among those that protect water and agriculture and limit their vulnerability. Soil erosion control practices are often based on long-term climatic averages. Special attention is needed to provide protection against average high-return frequency storms as well as severe storms with low-return frequency. Suitable and affordable soil conservation plans, coupled with an appropriate enabling environment, are needed. A watershed and community were selected in the mountainous area of North West Syria. The fields represent the non-tropical highland dry areas and dominated by olive orchards on steep slopes. Farmers were aware of resource degradation and productivity reduction, but lacked financial capital to implement the needed adaptation measures. A micro-credit system was established with the help of the UNDP Global Environment Facility - Small Grants Program (GEF-SGP) with small grants available for each farmer. Haphazard implementation on scattered fields proved inefficient in demonstrating obvious impact. Therefore, each watershed was classified into three erosion risk categories (high, moderate and low), derived from maps of flow accumulation, slope steepness, slope shape and land use. Using field survey of land ownership, the boundaries of 168 farms in the watersheds were mapped. Farmers' fields were classified using the erosion-risk map and considering the on-farm erosion hazard and the off-farm effect on other farmers' fields following the hillslope sequence. More than 60% of the farms were

  4. The erosive potential of candy sprays

    NARCIS (Netherlands)

    Gambon, D.L.; Brand, H.S.; Nieuw Amerongen, A.V.

    2009-01-01

    Objective To determine the erosive potential of seven different commercially available candy sprays in vitro and in vivo. Material and methods The erosive potential was determined in vitro by measuring the pH and neutralisable acidity. The salivary pH and flow rate were measured in healthy

  5. Riparian erosion vulnerability model based on environmental features.

    Science.gov (United States)

    Botero-Acosta, Alejandra; Chu, Maria L; Guzman, Jorge A; Starks, Patrick J; Moriasi, Daniel N

    2017-12-01

    Riparian erosion is one of the major causes of sediment and contaminant load to streams, degradation of riparian wildlife habitats, and land loss hazards. Land and soil management practices are implemented as conservation and restoration measures to mitigate the environmental problems brought about by riparian erosion. This, however, requires the identification of vulnerable areas to soil erosion. Because of the complex interactions between the different mechanisms that govern soil erosion and the inherent uncertainties involved in quantifying these processes, assessing erosion vulnerability at the watershed scale is challenging. The main objective of this study was to develop a methodology to identify areas along the riparian zone that are susceptible to erosion. The methodology was developed by integrating the physically-based watershed model MIKE-SHE, to simulate water movement, and a habitat suitability model, MaxEnt, to quantify the probability of presences of elevation changes (i.e., erosion) across the watershed. The presences of elevation changes were estimated based on two LiDAR-based elevation datasets taken in 2009 and 2012. The changes in elevation were grouped into four categories: low (0.5 - 0.7 m), medium (0.7 - 1.0 m), high (1.0 - 1.7 m) and very high (1.7 - 5.9 m), considering each category as a studied "species". The categories' locations were then used as "species location" map in MaxEnt. The environmental features used as constraints to the presence of erosion were land cover, soil, stream power index, overland flow, lateral inflow, and discharge. The modeling framework was evaluated in the Fort Cobb Reservoir Experimental watershed in southcentral Oklahoma. Results showed that the most vulnerable areas for erosion were located at the upper riparian zones of the Cobb and Lake sub-watersheds. The main waterways of these sub-watersheds were also found to be prone to streambank erosion. Approximatively 80% of the riparian zone (streambank

  6. Erosion of soil organic carbon: implications for carbon sequestration

    Science.gov (United States)

    Van Oost, Kristof; Van Hemelryck, Hendrik; Harden, Jennifer W.; McPherson, B.J.; Sundquist, E.T.

    2009-01-01

    Agricultural activities have substantially increased rates of soil erosion and deposition, and these processes have a significant impact on carbon (C) mineralization and burial. Here, we present a synthesis of erosion effects on carbon dynamics and discuss the implications of soil erosion for carbon sequestration strategies. We demonstrate that for a range of data-based parameters from the literature, soil erosion results in increased C storage onto land, an effect that is heterogeneous on the landscape and is variable on various timescales. We argue that the magnitude of the erosion term and soil carbon residence time, both strongly influenced by soil management, largely control the strength of the erosion-induced sink. In order to evaluate fully the effects of soil management strategies that promote carbon sequestration, a full carbon account must be made that considers the impact of erosion-enhanced disequilibrium between carbon inputs and decomposition, including effects on net primary productivity and decomposition rates.

  7. The water erosion processes in the retreat erosive of cliff on soft rocks in the province of Cadiz (Spain); Los procesos de erosion hidrica en el retroceso erosivo de acantilados sobre rocas blandas en la provincia de Cadiz

    Energy Technology Data Exchange (ETDEWEB)

    Rendon Aragon, J. J.; Gracia Prieto, F. J.; Rio Rodriguez, L. del

    2009-07-01

    The littoral cliffs on soft materials of the Atlantic Cadiz coast show an important activity of the fresh water erosion processes, sometimes even more significant than the marine erosion processes. The connection of the lower cliffs with sandy beaches favours aeolian sand invasion, which fills previous rills and reduces the water erosion intensity by increasing infiltration. Cliff retreat and rill erosion measurement by using erosion sticks has shown very variables values, most of them higher than the estimated error of the employed methods. This indicates the existence of other factors influencing the distribution of water erosion processes along these cliffs, which have to be studied through different techniques. (Author) 5 refs.

  8. Experimental study of the cavitation erosion in centrifugal pump impeller

    International Nuclear Information System (INIS)

    Rayan, M.A.

    1985-01-01

    Research on cavitation damage scale effects show that the damage rate is increased with size and velocity. It seems that for constant velocity there is no clear trend for the variation of erosion with cavitation number. Research on the time effects on damage rate show similarity between cavitation and impingement erosion. The cumulative weight loss versus time curve is of a ''S'' shaped type characterized by an incubation period followed by a period of increasing erosion rate, then a maximum erosion rate, and finally a period of decreasing erosion rate. The objective of this investigation is to present a prototype cavitation erosion experiment in order to clarify the time dependency of the erosive wear

  9. Numerical Modelling and Prediction of Erosion Induced by Hydrodynamic Cavitation

    Science.gov (United States)

    Peters, A.; Lantermann, U.; el Moctar, O.

    2015-12-01

    The present work aims to predict cavitation erosion using a numerical flow solver together with a new developed erosion model. The erosion model is based on the hypothesis that collapses of single cavitation bubbles near solid boundaries form high velocity microjets, which cause sonic impacts with high pressure amplitudes damaging the surface. The erosion model uses information from a numerical Euler-Euler flow simulation to predict erosion sensitive areas and assess the erosion aggressiveness of the flow. The obtained numerical results were compared to experimental results from tests of an axisymmetric nozzle.

  10. IN SITU MEASUREMENT OF BEDROCK EROSION

    Directory of Open Access Journals (Sweden)

    D. H. Rieke-Zapp

    2012-07-01

    Full Text Available While long term erosion rates of bedrock material may be estimated by dating methods, current day erosion rates are – if at all available – based on rough estimates or on point measurements. Precise quantification of short term erosion rates are required to improve our understanding of short term processes, for input in landscape evolution models, as well as for studying the mechanics and efficiency of different erosion processes in varying geomorphological settings. Typical current day erosion rates in the European Alps range from sub-millimetre to several millimetres per year depending on the dominant erosion processes. The level of surveying accuracy required for recurring sub-millimetre to millimetre measurements in the field is demanding. A novel surveying setup for in-situ measurement of bedrock erosion was tested recently in three different locations in Switzerland. Natural bedrock was investigated in the Gornera gorge close to Zermatt. Further on, bedrock samples were installed in exposed locations in the Erlenbach research watershed close to Einsiedeln, and in the Illgraben debris flow channel, located in the Canton Schwyz and Valais, respectively. A twofold measurement approach was chosen for all locations. For the first setup control points providing an absolute reference frame for recurrent measurements were embedded close to the area of interest. Close range photogrammetry was applied to measure surface changes on the bedrock samples. The precision for surface measurements in the field was 0.1 mm (1 σ and thus suitable for the application. The equipment needed for the surveys can easily be carried to the field. At one field site a structured light scanner was used along with the photogrammetric setup. Although the current generation of structured light scanners appeared less suitable for field application, data acquisition was much faster and checking the data for completeness in the field was straight forward. The latest

  11. In Situ Measurement of Bedrock Erosion

    Science.gov (United States)

    Rieke-Zapp, D. H.; Beer, A.; Turowski, J. M.; Campana, L.

    2012-07-01

    While long term erosion rates of bedrock material may be estimated by dating methods, current day erosion rates are - if at all available - based on rough estimates or on point measurements. Precise quantification of short term erosion rates are required to improve our understanding of short term processes, for input in landscape evolution models, as well as for studying the mechanics and efficiency of different erosion processes in varying geomorphological settings. Typical current day erosion rates in the European Alps range from sub-millimetre to several millimetres per year depending on the dominant erosion processes. The level of surveying accuracy required for recurring sub-millimetre to millimetre measurements in the field is demanding. A novel surveying setup for in-situ measurement of bedrock erosion was tested recently in three different locations in Switzerland. Natural bedrock was investigated in the Gornera gorge close to Zermatt. Further on, bedrock samples were installed in exposed locations in the Erlenbach research watershed close to Einsiedeln, and in the Illgraben debris flow channel, located in the Canton Schwyz and Valais, respectively. A twofold measurement approach was chosen for all locations. For the first setup control points providing an absolute reference frame for recurrent measurements were embedded close to the area of interest. Close range photogrammetry was applied to measure surface changes on the bedrock samples. The precision for surface measurements in the field was 0.1 mm (1 σ) and thus suitable for the application. The equipment needed for the surveys can easily be carried to the field. At one field site a structured light scanner was used along with the photogrammetric setup. Although the current generation of structured light scanners appeared less suitable for field application, data acquisition was much faster and checking the data for completeness in the field was straight forward. The latest generation of compact

  12. The social cost of coastal erosion. Using cultural theory to enrich the interpretation of stated preference data.

    Science.gov (United States)

    Kontogianni, A.; Tourkolias, C.; Vousdoukas, M.; Skourtos, M.

    2012-04-01

    Natural coastal processes are to a great extent modified by proximity to man-made structures. Engineered interventions, port facilities, housing and industrial infrastructure, all can increase the coastline fluctuations significantly relative to those along a long unobstructed coastline. As a consequence, coastlines are increasingly exposed to coastal erosion, a phenomenon defined as the encroachment of land by the sea after averaging over a period, which is sufficiently long to eliminate the impacts of weather, storm events and local sediment dynamics. In order to provide cost effective management of coastal erosion it is crucial to estimate both the benefits and costs associated with various management alternatives. The initiatives on Integrated Coastal Zone Manegment in Europe, but also the upcoming Marine Strategy Framwork Directive would benefit greatly from a proliferation of socioeconomic information to assist decision makers who must weigh the impacts of various types of coastal improvement and the cost of beach protection/restoration. In that spirit, the objective of the present research is to report the results of a survey undertaken in two resort beaches on the island of Lesvos (Greece), designed to estimate public preferences for avoiding coastal erosion. A mixed methodological approach is employed by combining an open-ended contingent valuation survey with cultural theory of risk perception. The empirical models to analyze individual choices of erosion control programs and the associated welfare measures are presented, followed by the discussion of model specification and estimation issues, and the results of the data analysis. Some concluding remarks are then presented. By choosing this approach we aim at improving our understanding of preference structure for avoiding public risk, accepted level of risk and perceptions thereof. The framework can also be used for assessing the social cost of extreme weather events such as storm surges in the coastal

  13. Assessment of soil erosion and sedimentation through the use of the 137Cs and related techniques

    International Nuclear Information System (INIS)

    Queralt, I.; Zapata, F.; Garcia Agudo, E.

    2000-01-01

    During the last decades the international scientific community has been increasingly aware of both the risk and the effects of soil erosion and sedimentation processes cause to sustainable agricultural activities and the quality of the superficial environment. Soil erosion is a major environmental worldwide concern of our time. Over the past thirty years two main streams of thought have developed about the effects of soil erosion. The first one, mainly based on ecologist and environmentalist criteria, believes that soil erosion is a true disease on the land that quickly depletes the soil production capacity with some additional subsequent effects such as eutrophication of water reservoirs and pollution of natural waters. The second one supports that soil erosion is a natural process shaping the overall landscape. Development of fertile soils on river valleys can be attributed to erosion processes in the upper reaches of catchment. Loss of productivity due to soil erosion on agricultural lands can be easily compensated by small addition of fertilisers . W h a t ever position we adopt a development of methods offering reliable data is needed. The use of models based on radiogenic isotopes distribution in soil profiles can offer valuable data set both in soil erosion and deposition. In addition, soil redistribution can be effectively assessed. These methods can be applied in a huge range of soil conditions in different geographic zones and the results are comparable at global scale. The International Atomic Energy Agency (IAEA) sponsored since 1995, the implementation of two co-ordinated research projects (CRP's) dealing with the application of the 137 Cs technique in soil erosion and sedimentation studies respectively. A joint Meeting of both CRP's was organised by the Land and Water Conservation Group of the Institute of Earth Sciences 'Jaume Almera', CSIC, in Barcelona, Spain, from 4 to 8 October 1999. This Special Issue of Acta Geologica Hispanica contains a

  14. [Research progress on wind erosion control with polyacrylamide (PAM).

    Science.gov (United States)

    Li, Yuan Yuan; Wang, Zhan Li

    2016-03-01

    Soil wind erosion is one of the main reasons for soil degradation in the northwest region of China. Polyacrylamide (PAM), as an efficient soil amendment, has gained extensive attention in recent years since it is effective in improving the structure of surface soil due to its special physical and chemical properties. This paper introduced the physical and chemical properties of PAM, reviewed the effects of PAM on soil wind erosion amount and threshold wind velocity, as well as the effect differences of PAM in soil wind erosion control under conditions of various methods and doses. Its effect was proved by comparing with other materials in detail. Furthermore, we analyzed the mecha-nism of wind erosion control with PAM according to its influence on soil physical characteristics. Comprehensive analysis showed that, although some problems existed in wind erosion control with (PAM), PAM as a sand fixation agent, can not only enhance the capacity of the soil resis-tance to wind erosion, but also improve soil physical properties to form better soil conditions. Besides, we proposed that combination of PAM and plant growth would increase the survival rate of plants greatly, control soil wind erosion in wind-erosive areas, and improve the quality of the ecological environment construction. Thus, PAM has practically important significance and wide application prospect in controlling soil wind erosion.

  15. Coupling of phenological information and simulated vegetation index time series: Limitations and potentials for the assessment and monitoring of soil erosion risk

    Science.gov (United States)

    Monitoring of agricultural used soils at frequent intervals is needed to get a sufficient understanding of soil erosion processes. This is crucial to support decision making and refining soil policies especially in the context of climate change. Along with rainfall erosivity, soil coverage by vegeta...

  16. The use of radionuclide techniques in soil erosion studies

    International Nuclear Information System (INIS)

    Bernard, C.; Mabit, L.

    2006-01-01

    run these models. Besides CRPs, the Agency is also involved in several national and regional technical cooperation projects (TCPs) that are related to the use of FRNs for erosion measurements. Through technical cooperation, technical and scientific capacity is built in the participating countries by providing scientific equipment as well as technical training, scientific and expert visits. The Agency is also supportive of Member States by hosting several scientific visitors and fellows, for their training, so they can benefit from the expertise of the SSU's and SWMCN's staff and from the equipment and research facilities in the Agency's laboratories in Seibersdorf. A new individual fellowship program on 'Erosion process assessment using nuclear techniques' has been created at the SSU. The program covers all the topics related to the use of FRNs to estimate erosion: introduction to erosion processes, sampling strategy at the field and/or watershed scale, sample preparation for gamma analysis, introduction to geostatistical analysis, mapping, analysis and interpretation of data, conversion models. Finally, in order to support the research and technical cooperation programs, internal research projects using 137 Cs to quantify soil loss risks at the watershed scale are being implemented by the SSU, in collaboration with Boku University

  17. Temporal and spatial variations of rainfall erosivity in Southern Taiwan

    Science.gov (United States)

    Lee, Ming-Hsi; Lin, Huan-Hsuan; Chu, Chun-Kuang

    2014-05-01

    Soil erosion models are essential in developing effective soil and water resource conservation strategies. Soil erosion is generally evaluated using the Universal Soil Loss Equation (USLE) with an appropriate regional scale description. Among factors in the USLE model, the rainfall erosivity index (R) provides one of the clearest indications of the effects of climate change. Accurate estimation of rainfall erosivity requires continuous rainfall data; however, such data rarely demonstrate good spatial and temporal coverage. The data set consisted of 9240 storm events for the period 1993 to 2011, monitored by 27 rainfall stations of the Central Weather Bureau (CWB) in southern Taiwan, was used to analyze the temporal-spatial variations of rainfall erosivity. The spatial distribution map was plotted based on rainfall erosivity by the Kriging interpolation method. Results indicated that rainfall erosivity is mainly concentrated in rainy season from June to November typically contributed 90% of the yearly R factor. The temporal variations of monthly rainfall erosivity during June to November and annual rainfall erosivity have increasing trend from 1993 to 2011. There is an increasing trend from southwest to northeast in spatial distribution of rainfall erosivity in southern Taiwan. The results further indicated that there is a higher relationship between elevation and rainfall erosivity. The method developed in this study may also be useful for sediment disasters on Climate Change.

  18. Rainfall erosivity in Brazil: A Review

    Science.gov (United States)

    In this paper, we review the erosivity studies conducted in Brazil to verify the quality and representativeness of the results generated and to provide a greater understanding of the rainfall erosivity (R-factor) in Brazil. We searched the ISI Web of Science, Scopus, SciELO, and Google Scholar datab...

  19. Backward erosion piping : Initiation and progression

    NARCIS (Netherlands)

    Van Beek, V.M.

    2015-01-01

    Backward erosion piping is an internal erosion mechanism during which shallow pipes are formed in the direction opposite to the flow underneath water-retaining structures as a result of the gradual removal of sandy material by the action of water. It is an important failure mechanism in both dikes

  20. RECURRENT CORNEAL EROSION SYNDROME (a review

    Directory of Open Access Journals (Sweden)

    S. V. Trufanov

    2015-01-01

    Full Text Available Recurrent corneal erosion (RCE syndrome is characterized by episodes of recurrent spontaneous epithelial defects. Main clinical symptoms (pain, redness, photophobia, lacrimation occurred at night. Corneal lesions revealed by slit lamp exam vary depending on the presence of corneal epithelium raise, epithelial microcysts or epithelial erosions, stromal infiltrates and opacities. Microtraumas, anterior corneal dystrophies, and herpesvirus give rise to RCE. Other causes or factors which increase the risk of RCE syndrome include meibomian gland dysfunction, keratoconjunctivitis sicca, diabetes, and post-LASIK conditions. Basal membrane abnormalities and instability of epithelial adhesion to stroma play a key role in RCE pathogenesis. Ultrastructural changes in RCE include abnormalities of basal epithelial cells and epithelial basal membrane, absence or deficiency of semi-desmosomes, loss of anchor fibrils. Increase in matrix metalloproteinases and collagenases which contribute to basal membrane destruction results in recurrent erosions and further development of abnormal basal membrane. The goals of RCE therapy are to reduce pain (in acute stage, to stimulate re-epithelization, and to restore «adhesion complex» of basal membrane. In most cases, RCE responds to simple conservative treatment that includes lubricants, healing agents, and eye patches. RCEs that are resistant to simple treatment, require complex approach. Non-invasive methods include long-term contact lens use, instillations of autologous serum (eye drops, injections of botulinum toxin (induces ptosis, antiviral agent use or oral intake of metalloproteinase inhibitors. Cell membrane stabilizers, i.e., antioxidants, should be included into treatment approaches as well. Antioxidant effect of Emoxipine promotes tissue reparation due to the prevention of cell membrane lipid peroxidation as well as due to its anti-hypoxic, angioprotective, and antiplatelet effects. If conservative therapy

  1. Modeling of technical soil-erosion control measures and its impact on soil erosion off-site effects within urban areas

    Science.gov (United States)

    Dostal, Tomas; Devaty, Jan

    2013-04-01

    The paper presents results of surface runoff, soil erosion and sediment transport modeling using Erosion 3D software - physically based mathematical simulation model, event oriented, fully distributed. Various methods to simulate technical soil-erosion conservation measures were tested, using alternative digital elevation models of different precision and resolution. Ditches and baulks were simulated by three different approaches, (i) by change of the land-cover parameters to increase infiltration and decrease flow velocity, (ii) by change of the land-cover parameters to completely infiltrate the surface runoff and (iii) by adjusting the height of the digital elevation model by "burning in" the channels of the ditches. Results show advantages and disadvantages of each approach and conclude suitable methods for combinations of particular digital elevation model and purpose of the simulations. Further on a set of simulations was carried out to model situations before and after technical soil-erosion conservation measures application within a small catchment of 4 km2. These simulations were focused on quantitative and qualitative assessment of technical soil-erosion control measures impact on soil erosion off-site effects within urban areas located downstream of intensively used agricultural fields. The scenarios were built upon a raster digital elevation model with spatial resolution of 3 meters derived from LiDAR 5G vector point elevation data. Use of this high-resolution elevation model allowed simulating the technical soil-erosion control measures by direct terrain elevation adjustment. Also the structures within the settlements were emulated by direct change in the elevation of the terrain model. The buildings were lifted up to simulate complicated flow behavior of the surface runoff within urban areas, using approach of Arévalo (Arévalo, 2011) but focusing on the use of commonly available data without extensive detailed editing. Application of the technical

  2. High natural erosion rates are the backdrop for enhanced anthropogenic soil erosion in the Middle Hills of Nepal

    Science.gov (United States)

    West, A. J.; Arnold, M.; Aumaître, G.; Bourlès, D. L.; Keddadouche, K.; Bickle, M.; Ojha, T.

    2014-08-01

    Although agriculturally accelerated soil erosion is implicated in the unsustainable environmental degradation of mountain environments, such as in the Himalaya, the effects of land use can be difficult to quantify in many mountain settings because of the high and variable natural background rates of erosion. In this study, we present new long-term denudation rates, derived from cosmogenic 10Be analysis of quartz in river sediment from the Likhu Khola, a small agricultural river basin in the Middle Hills of central Nepal. Calculated long-term denudation rates, which reflect background natural erosion processes over 1000+ years prior to agricultural intensification, are similar to present-day sediment yields and to soil loss rates from terraces that are well-maintained. Similarity in short- and long-term catchment-wide erosion rates for the Likhu is consistent with data from elsewhere in the Nepal Middle Hills, but contrasts with the very large increases in short-term erosion rates seen in agricultural catchments in other steep mountain settings. Our results suggest that the large sediment fluxes exported from the Likhu and other Middle Hills rivers in the Himalaya are derived in large part from natural processes, rather than from soil erosion as a result of agricultural activity. Because of the high natural background rates, simple comparison of short- and long-term rates may not reveal unsustainable soil degradation, particularly if much of the catchment-scale erosion flux derives from mass wasting. Correcting for the mass wasting contribution in the Likhu implies minimum catchment-averaged soil production rates of ~0.25-0.35 mm yr-1. The deficit between these production rates and soil losses suggests that terraced agriculture in the Likhu may not be associated with a large systematic soil deficit, at least when terraces are well maintained, but that poorly managed terraces, forest and scrubland may lead to rapid depletion of soil resources.

  3. Community and Institutional Adaptation to Riverbank Erosion along the Jamuna River, Bangladesh

    Science.gov (United States)

    Ali, F. M. M.

    2009-04-01

    The paper examines adaptation to the river erosion hazard in Bangladesh through its most exacting river, the braided Jamuna. The Jamuna River has destroyed and continues to threaten significant areas of settlements, farmed land and infrastructure. Local communities experience a social disintegration and pauperisation which lasts for generations. Although advanced for several decades, the public engineering effort to mitigate the erosion is piecemeal and has had limited success to date. The research takes an interdisciplinary approach to the hazard, in both content and method. Using Remote Sensing data to distinguish regions of dormant, explosive, minimal and constant erosion, the physical morphology of the river is linked to the community adaptation through the creation of PPGIS mapping depicting historical institutional displacement. This spatial information is linked to the qualitative investigation focusing on the expression of values in adaptation by examining social structures and investigating technological development. Drawing on Bourdieu's ideas of fields, capital and habitus, interview data is gathered from: displacees; local elites; the engineering-science community; and the political-administrative structure. The analysis is conducted along four themes; the spatial history of community displacement; social values; institutional operation; and learning in practice. Findings show the marked persistence of displaced local institutions. Dormant erosion zones host the most displaced institutions, acting as refuges once the risk is lowered through engineering or serendipity. The non-material values deeply impacted by the hazard underpin the strong local aspiration for engineering intervention. However, political discontinuity, associated institutional instability and spatial biasing of construction hinders the success of erosion mitigation and the development of appropriate national technological expertise. The small national economic resource base

  4. LiDAR derived high resolution topography: the next challenge for the analysis of terraces stability and vineyard soil erosion

    Directory of Open Access Journals (Sweden)

    Federico Preti

    2013-09-01

    Full Text Available The soil erosion in the vineyards is a critical issue that could affect their productivity, but also, when the cultivation is organized in terraces, increase the risk due to derived slope failure processes. If terraces are not correctly designed or maintained, a progressively increasing of gully erosion affects the structure of the walls. The results of this process is the increasing of connectivity and runoff. In order to overcome such issues it is really important to recognize in detail all the surface drainage paths, thus providing a basis upon which develop a suitable drainage system or provide structural measures for the soil erosion risk mitigation. In the last few years, the airborne LiDAR technology led to a dramatic increase in terrain information. Airborne LiDAR and Terrestrial Laser Scanner derived high-resolution Digital Terrain Models (DTMs have opened avenues for hydrologic and geomorphologic studies (Tarolli et al., 2009. In general, all the main surface process signatures are correctly recognized using a DTM with cell sizes of 1 m. However sub-meter grid sizes may be more suitable in those situations where the analysis of micro topography related to micro changes is critical for slope failures risk assessment or for the design of detailed drainage flow paths. The Terrestrial Laser Scanner (TLS has been proven to be an useful tool for such detailed field survey. In this work, we test the effectiveness of high resolution topography derived by airborne LiDAR and TLS for the recognition of areas subject to soil erosion risk in a typical terraced vineyard landscape of “Chianti Classico” (Tuscany, Italy. The algorithm proposed by Tarolli et al. (2013, for the automatic recognition of anthropic feature induced flow direction changes, has been tested. The results underline the effectiveness of LiDAR and TLS data in the analysis of soil erosion signatures in vineyards, and indicate the high resolution topography as a useful tool to

  5. Double Ramp Loss Based Reject Option Classifier

    Science.gov (United States)

    2015-05-22

    of convex (DC) functions. To minimize it, we use DC programming approach [1]. The proposed method has following advantages: (1) the proposed loss LDR ...space constraints. We see that LDR does not put any restriction on ρ for it to be an upper bound of L0−d−1. 2.2 Risk Formulation Using LDR Let S = {(xn...classifier learnt using LDR based approach (C = 100, μ = 1, d = .2). Filled circles and triangles represent the support vectors. 4 Experimental Results We show

  6. Erosivity of rainfall in Lages, Santa Catarina, Brazil

    Directory of Open Access Journals (Sweden)

    Jefferson Schick

    2014-12-01

    Full Text Available The erosive capacity of rainfall can be expressed by an index and knowing it allows recommendation of soil management and conservation practices to reduce water erosion. The objective of this study was to calculate various indices of rainfall erosivity in Lages, Santa Catarina, Brazil, identify the best one, and discover its temporal distribution. The study was conducted at the Center of Agricultural and Veterinary Sciences, Lages, Santa Catarina, using daily rainfall charts from 1989 to 2012. Using the computer program Chuveros , 107 erosivity indices were obtained, which were based on maximum intensity in 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 70, 80, 90, 100, 110, 120, 135, 150, 165, 180, 210, and 240 min of duration and on the combination of these intensities with the kinetic energy obtained by the equations of Brown & Foster, Wagner & Massambani, and Wischmeier & Smith. The indices of the time period from 1993 to 2012 were correlated with the respective soil losses from the standard plot of the Universal Soil Loss Equation (USLE in order to select the erosivity index for the region. Erosive rainfall accounted for 83 % of the mean annual total volume of 1,533 mm. The erosivity index (R factor of rainfall recommended for Lages is the EI30, whose mean annual value is 5,033 MJ mm ha-1 h-1, and of this value, 66 % occurs from September to February. Mean annual erosivity has a return period estimated at two years with a 50 % probability of occurrence.

  7. Acquired pellicle as a modulator for dental erosion.

    Science.gov (United States)

    Vukosavljevic, Dusa; Custodio, William; Buzalaf, Marilia A R; Hara, Anderson T; Siqueira, Walter L

    2014-06-01

    Dental erosion is a multifactorial condition that can result in the loss of tooth structure and function, potentially increasing tooth sensitivity. The exposure of enamel to acids from non-bacterial sources is responsible for the progression of erosion. These erosive challenges are counteracted by the anti-erosive properties of the acquired pellicle (AP), an integument formed in vivo as a result of selective adsorption of salivary proteins on the tooth surface, containing also lipids and glycoproteins. This review provides an in-depth discussion regarding how the physical structure of the AP, along with its composition, contributes to AP anti-erosive properties. The physical properties that contribute to AP protective nature include pellicle thickness, maturation time, and site of development. The pellicle contains salivary proteins embedded within its structure that demonstrate anti-erosive properties; however, rather than individual proteins, protein-protein interactions play a fundamental role in the protective nature of the AP. In addition, dietary and synthetic proteins can modify the pellicle, enhancing its protective efficiency against dental erosion. The salivary composition of the AP and its corresponding protein-profile may be employed as a diagnostic tool, since it likely contains salivary biomarkers for oral diseases that initiate at the enamel surface, including dental erosion. Finally, by modifying the composition and structure of the AP, this protein integument has the potential to be used as a target-specific treatment option for oral diseases related to tooth demineralization. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  8. Soil erosion under multiple time-varying rainfall events

    Science.gov (United States)

    Heng, B. C. Peter; Barry, D. Andrew; Jomaa, Seifeddine; Sander, Graham C.

    2010-05-01

    Soil erosion is a function of many factors and process interactions. An erosion event produces changes in surface soil properties such as texture and hydraulic conductivity. These changes in turn alter the erosion response to subsequent events. Laboratory-scale soil erosion studies have typically focused on single independent rainfall events with constant rainfall intensities. This study investigates the effect of multiple time-varying rainfall events on soil erosion using the EPFL erosion flume. The rainfall simulator comprises ten Veejet nozzles mounted on oscillating bars 3 m above a 6 m × 2 m flume. Spray from the nozzles is applied onto the soil surface in sweeps; rainfall intensity is thus controlled by varying the sweeping frequency. Freshly-prepared soil with a uniform slope was subjected to five rainfall events at daily intervals. In each 3-h event, rainfall intensity was ramped up linearly to a maximum of 60 mm/h and then stepped down to zero. Runoff samples were collected and analysed for particle size distribution (PSD) as well as total sediment concentration. We investigate whether there is a hysteretic relationship between sediment concentration and discharge within each event and how this relationship changes from event to event. Trends in the PSD of the eroded sediment are discussed and correlated with changes in sediment concentration. Close-up imagery of the soil surface following each event highlight changes in surface soil structure with time. This study enhances our understanding of erosion processes in the field, with corresponding implications for soil erosion modelling.

  9. Ash particle erosion on steam boiler convective section

    Energy Technology Data Exchange (ETDEWEB)

    Meuronen, V

    1998-12-31

    In this study, equations for the calculation of erosion wear caused by ash particles on convective heat exchanger tubes of steam boilers are presented. A new, three-dimensional test arrangement was used in the testing of the erosion wear of convective heat exchanger tubes of steam boilers. When using the sleeve-method, three different tube materials and three tube constructions could be tested. New results were obtained from the analyses. The main mechanisms of erosion wear phenomena and erosion wear as a function of collision conditions and material properties have been studied. Properties of fossil fuels have also been presented. When burning solid fuels, such as pulverized coal and peat in steam boilers, most of the ash is entrained by the flue gas in the furnace. In bubbling and circulating fluidized bed boilers, particle concentration in the flue gas is high because of bed material entrained in the flue gas. Hard particles, such as sharp edged quartz crystals, cause erosion wear when colliding on convective heat exchanger tubes and on the rear wall of the steam boiler. The most important ways to reduce erosion wear in steam boilers is to keep the velocity of the flue gas moderate and prevent channelling of the ash flow in a certain part of the cross section of the flue gas channel, especially near the back wall. One can do this by constructing the boiler with the following components. Screen plates can be used to make the velocity and ash flow distributions more even at the cross-section of the channel. Shield plates and plate type constructions in superheaters can also be used. Erosion testing was conducted with three types of tube constructions: a one tube row, an in- line tube bank with six tube rows, and a staggered tube bark with six tube rows. Three flow velocities and two particle concentrations were used in the tests, which were carried out at room temperature. Three particle materials were used: quartz, coal ash and peat ash particles. Mass loss

  10. Effect of mechanical properties on erosion resistance of ductile materials

    Science.gov (United States)

    Levin, Boris Feliksovih

    Solid particle erosion (SPE) resistance of ductile Fe, Ni, and Co-based alloys as well as commercially pure Ni and Cu was studied. A model for SPE behavior of ductile materials is presented. The model incorporates the mechanical properties of the materials at the deformation conditions associated with SPE process, as well as the evolution of these properties during the erosion induced deformation. An erosion parameter was formulated based on consideration of the energy loss during erosion, and incorporates the material's hardness and toughness at high strain rates. The erosion model predicts that materials combining high hardness and toughness can exhibit good erosion resistance. To measure mechanical properties of materials, high strain rate compression tests using Hopkinson bar technique were conducted at strain rates similar to those during erosion. From these tests, failure strength and strain during erosion were estimated and used to calculate toughness of the materials. The proposed erosion parameter shows good correlation with experimentally measured erosion rates for all tested materials. To analyze subsurface deformation during erosion, microhardness and nanoindentation tests were performed on the cross-sections of the eroded materials and the size of the plastically deformed zone and the increase in materials hardness due to erosion were determined. A nanoindentation method was developed to estimate the restitution coefficient within plastically deformed regions of the eroded samples which provides a measure of the rebounding ability of a material during particle impact. An increase in hardness near the eroded surface led to an increase in restitution coefficient. Also, the stress rates imposed below the eroded surface were comparable to those measured during high strain-rate compression tests (10sp3-10sp4 ssp{-1}). A new parameter, "area under the microhardness curve" was developed that represents the ability of a material to absorb impact energy. By

  11. Polymers Erosion and Contamination Experiment Being Developed

    Science.gov (United States)

    deGroh, Kim K.; Banks, Bruce A.; Barney-Barton, Elyse A.; Sechkar, Edward; Hunt, Patricia

    1999-01-01

    The Polymers Erosion and Contamination Experiment (PEACE) is currently being developed at the NASA Lewis Research Center by the Electro-Physics Branch in conjunction with students and faculty from Hathaway Brown School in Cleveland. The experiment is a Get Away Special Canister shuttle flight experiment sponsored by the American Chemical Society. The two goals of this experiment are (1) to measure ram atomic oxygen erosion rates of approximately 40 polymers that have potential use in space applications and (2) to validate a method for identifying sources of silicone contamination that occur in the shuttle bay. Equipment to be used in this flight experiment is shown in the schematic diagram. Spacecraft materials subjected to attack by atomic oxygen in the space environment experience significant degradation over the span of a typical mission. Therefore, learning the rates of atomic oxygen erosion of a wide variety of polymers would be of great benefit to future missions. PEACE will use two independent techniques to determine the atomic oxygen erosion rates of polymers. Large (1-in.-diameter) samples will be used for obtaining mass loss. Preflight and postflight dehydrated masses will be obtained, and the mass lost during flight will be determined. Small (0.5-in.-diameter) samples will be protected with isolated particles (such as NaCl crystals) and then exposed to the space environment. After flight, the protective particles will be removed (washed off) and atomic force microscopy (AFM) will be used to measure the erosion depth from protected mesas. Erosion depth measurements are more sensitive than traditional mass measurements and are very useful for materials with low erosion yields or with very low fluence missions.

  12. Rainfall erosivity in subtropical catchments and implications for erosion and particle-bound contaminant transfer: a case-study of the Fukushima region

    Science.gov (United States)

    Laceby, J. P.; Chartin, C.; Evrard, O.; Onda, Y.; Garcia-Sanchez, L.; Cerdan, O.

    2015-07-01

    The Fukushima Dai-ichi nuclear power plant (FDNPP) accident in March 2011 resulted in a significant fallout of radiocesium over the Fukushima region. After reaching the soil surface, radiocesium is almost irreversibly bound to fine soil particles. Thereafter, rainfall and snow melt run-off events transfer particle-bound radiocesium downstream. Erosion models, such as the Universal Soil Loss Equation (USLE), depict a proportional relationship between rainfall and soil erosion. As radiocesium is tightly bound to fine soil and sediment particles, characterizing the rainfall regime of the fallout-impacted region is fundamental to modelling and predicting radiocesium migration. Accordingly, monthly and annual rainfall data from ~ 60 meteorological stations within a 100 km radius of the FDNPP were analysed. Monthly rainfall erosivity maps were developed for the Fukushima coastal catchments illustrating the spatial heterogeneity of rainfall erosivity in the region. The mean average rainfall in the Fukushima region was 1387 mm yr-1 (σ 230) with the mean rainfall erosivity being 2785 MJ mm ha-1 yr-1 (σ 1359). The results indicate that the majority of rainfall (60 %) and rainfall erosivity (86 %) occurs between June and October. During the year, rainfall erosivity evolves positively from northwest to southeast in the eastern part of the prefecture, whereas a positive gradient from north to south occurs in July and August, the most erosive months of the year. During the typhoon season, the coastal plain and eastern mountainous areas of the Fukushima prefecture, including a large part of the contamination plume, are most impacted by erosive events. Understanding these rainfall patterns, particularly their spatial and temporal variation, is fundamental to managing soil and particle-bound radiocesium transfers in the Fukushima region. Moreover, understanding the impact of typhoons is important for managing sediment transfers in subtropical regions impacted by cyclonic activity.

  13. Optimal parameter selection for qualitative regional erosion risk monitoring: A remote sensing study of SE Ethiopia

    Directory of Open Access Journals (Sweden)

    Moncef Bouaziz

    2011-04-01

    Maps derived from this qualitative analysis allow the identification and ranking of erosion intensity. These maps enable us to highlight areas in immediate need of conservation strategies in order to control siltation of the SE Ethiopian reservoir and to control further soil degradation.

  14. Erosion properties of unipolar arcs

    International Nuclear Information System (INIS)

    Chekalin, Eh.K.

    1982-01-01

    Processes modelling the formation of unipolar arcs on the elements of the first wall in limiters of the vacuum chamber and on active elements of tokamak divertor, are experimentally investigated. Erosion, processes that take place at two types of non-stationary cathode spots are considered. Experimental data prove the possibility of reducing erosion intensity by coating the surface of electrodes by oxide films, reduction of the temperature of electrode and discharge current

  15. Using multivariate machine learning methods and structural MRI to classify childhood onset schizophrenia and healthy controls

    Directory of Open Access Journals (Sweden)

    Deanna eGreenstein

    2012-06-01

    Full Text Available Introduction: Multivariate machine learning methods can be used to classify groups of schizophrenia patients and controls using structural magnetic resonance imaging (MRI. However, machine learning methods to date have not been extended beyond classification and contemporaneously applied in a meaningful way to clinical measures. We hypothesized that brain measures would classify groups, and that increased likelihood of being classified as a patient using regional brain measures would be positively related to illness severity, developmental delays and genetic risk. Methods: Using 74 anatomic brain MRI sub regions and Random Forest, we classified 98 COS patients and 99 age, sex, and ethnicity-matched healthy controls. We also used Random Forest to determine the likelihood of being classified as a schizophrenia patient based on MRI measures. We then explored relationships between brain-based probability of illness and symptoms, premorbid development, and presence of copy number variation associated with schizophrenia. Results: Brain regions jointly classified COS and control groups with 73.7% accuracy. Greater brain-based probability of illness was associated with worse functioning (p= 0.0004 and fewer developmental delays (p=0.02. Presence of copy number variation (CNV was associated with lower probability of being classified as schizophrenia (p=0.001. The regions that were most important in classifying groups included left temporal lobes, bilateral dorsolateral prefrontal regions, and left medial parietal lobes. Conclusions: Schizophrenia and control groups can be well classified using Random Forest and anatomic brain measures, and brain-based probability of illness has a positive relationship with illness severity and a negative relationship with developmental delays/problems and CNV-based risk.

  16. Erosive effects of common beverages on extracted premolar teeth.

    Science.gov (United States)

    Seow, W K; Thong, K M

    2005-09-01

    Dental erosion is highly prevalent today, and acidic drinks are thought to be an important cause. The aim of the present investigation was to determine the erosive potential of a range of common beverages on extracted human teeth. The beverages were tested for their individual pHs using a pH meter. The clinical effects of the most erosive beverages were determined by the degree of etching and Vickers microhardness of enamel. The results showed that many common beverages have pHs sufficiently low to cause enamel erosion. Lime juice concentrate (pH 2.1) had the lowest pH, followed by Coca-cola and Pepsi (both with pH 2.3) and Lucozade (pH 2.5). The erosive potential of these beverages was demonstrated by the deep etching of the enamel after five minutes. The Vickers Hardness of enamel was reduced by about 50 per cent in the case of lime juice (p case of Coca-cola (p Coca-cola completely reversed the erosive effects on the enamel. Although only a few of the beverages with the lowest pHs were tested, the present study showed that the most acidic drinks had the greatest erosive effects on enamel. While saliva was protective against erosion, relatively large volumes were required to neutralize the acidity.

  17. Spatial patterns of diversity and genetic erosion of traditional cassava (Manihot esculenta Crantz) cultivation in the Peruvian Amazon: an evaluation of socio-economic and environmental indicators

    NARCIS (Netherlands)

    Willemen, L.; Scheldeman, X.; Soto Cabellos, V.; Salazar, S.R.; Guarino, L.

    2007-01-01

    This study evaluates quantitatively the suitability of the use of site-specific socio-economic and environmental data as indicators to rapidly assess patterns of diversity and genetic erosion risk in cassava. Socio-economic data as well as farmers¿ estimation of genetic erosion were collected in the

  18. Rethinking erosion on Java: a reaction

    NARCIS (Netherlands)

    Graaff, de J.; Wiersum, K.F.

    1992-01-01

    In a recent article (Diemont et al., 1991) about erosion on Java, it has been postulated that low inputs, not surface erosion, is the main cause of low productivity of upland food crops on this island. In this article it is argued that this hypothesis is too simple. An analysis of empirical field

  19. SpectraClassifier 1.0: a user friendly, automated MRS-based classifier-development system

    Directory of Open Access Journals (Sweden)

    Julià-Sapé Margarida

    2010-02-01

    Full Text Available Abstract Background SpectraClassifier (SC is a Java solution for designing and implementing Magnetic Resonance Spectroscopy (MRS-based classifiers. The main goal of SC is to allow users with minimum background knowledge of multivariate statistics to perform a fully automated pattern recognition analysis. SC incorporates feature selection (greedy stepwise approach, either forward or backward, and feature extraction (PCA. Fisher Linear Discriminant Analysis is the method of choice for classification. Classifier evaluation is performed through various methods: display of the confusion matrix of the training and testing datasets; K-fold cross-validation, leave-one-out and bootstrapping as well as Receiver Operating Characteristic (ROC curves. Results SC is composed of the following modules: Classifier design, Data exploration, Data visualisation, Classifier evaluation, Reports, and Classifier history. It is able to read low resolution in-vivo MRS (single-voxel and multi-voxel and high resolution tissue MRS (HRMAS, processed with existing tools (jMRUI, INTERPRET, 3DiCSI or TopSpin. In addition, to facilitate exchanging data between applications, a standard format capable of storing all the information needed for a dataset was developed. Each functionality of SC has been specifically validated with real data with the purpose of bug-testing and methods validation. Data from the INTERPRET project was used. Conclusions SC is a user-friendly software designed to fulfil the needs of potential users in the MRS community. It accepts all kinds of pre-processed MRS data types and classifies them semi-automatically, allowing spectroscopists to concentrate on interpretation of results with the use of its visualisation tools.

  20. Protection of uranium tailings impoundments against overland erosion

    International Nuclear Information System (INIS)

    Walters, W.H.; Skaggs, R.L.

    1986-01-01

    This study investigates the problems involved in designing protection methods to prevent erosion of a uranium tailings impoundment cover from rainfall and runoff (overland flow) processes. The study addresses the side slopes and top surface as separate elements. The side slopes are more subject to gully erosion and require absolute protection such as that provided by rock riprap. The flatter top surface needs much less protection (vegetation/rock combinations) but some estimate of erosion rates are needed to compare alternatives. A literature review indicated that, currently, procedures are not available for the design of rock riprap to prevent gully erosion. Therefore, rock protection on the side slope will have to be based upon engineering judgment determined by the particular site conditions. The Manning-kinetic equations (velocity and depth of runoff) were investigated as a possible aid to the design of gully erosion protection. Guidelines are suggested for the use of rock riprap to prevent gully erosion. Three mathematical models were used to compute erosion rates for the top surface of a hypothetical tailings impoundment. The results recommend that one or possibly both of the regression models could be used to evaluate preliminary protection designs for the top surface. A physical process simulation model should be used for the final design. 30 refs., 13 figs., 16 tabs

  1. Wind erosion control of soils using polymeric materials

    Directory of Open Access Journals (Sweden)

    Mohammad Movahedan

    2012-07-01

    Full Text Available Wind erosion of soils is one of the most important problems in environment and agriculture which could affects several fields. Agricultural lands, water reservoires, irrigation canals, drains and etc. may be affected by wind erosion and suspended particles. As a result wind erosion control needs attention in arid and semi-arid regions. In recent years, some polymeric materials have been used for improvement of structural stability, increasing aggregate stability and soil stabilization, though kind of polymer, quantity of polymer, field efficiency and durability and environmental impacts are some important parameters which should be taken into consideration. In this study, a Polyvinil Acetate-based polymer was used to treat different soils. Then polymer-added soil samples were investigated experimentally in a wind tunnel to verify the effecte of polymer on wind erosion control of the soils and the results were compared with water treated soil samples. The results of wind tunnel experiments with a maximum 26 m/s wind velocity showed that there was a significat difference between the erosion of polymer treated and water treated soil samples. Application of 25g/m2 polymer to Aeolian sands reduced the erosion of Aeolian sands samples to zero related to water treated samples. For silty and calyey soils treated by polymer, the wind erosion reduced minimum 90% in relation to water treated samples.

  2. Application of Coal Ash to Postmine Land for Prevention of Soil Erosion in Coal Mine in Indonesia: Utilization of Fly Ash and Bottom Ash

    Directory of Open Access Journals (Sweden)

    Shinji Matsumoto

    2016-01-01

    Full Text Available The increase in the number of coal-fired power plants with the increase in coal production and its consumption has caused the problem of the treatment of a large amount of coal ash in Indonesia. In the past studies, coal ash was applied to postmine land with the aim of improving soil conditions for plant growth; however, heavy rain in the tropical climate may cause soil erosion with the change in soil conditions. This study presents the effects of application of coal ash to postmine land on soil erosion by performing the artificial rainfall test as well as physical testing. The results indicate that the risk of soil erosion can be reduced significantly by applying the coal ash which consists of more than 85% of sand to topsoil in the postmine land at the mixing ratio of over 30%. Additionally, they reveal that not only fine fractions but also microporous structures in coal ash enhance water retention capacity by retaining water in the structure, leading to the prevention of soil erosion. Thus, the risk of soil erosion can be reduced by applying coal ash to topsoil in consideration of soil composition and microporous structure of coal ash.

  3. Analysis of Artificial Neural Network in Erosion Modeling: A Case Study of Serang Watershed

    Science.gov (United States)

    Arif, N.; Danoedoro, P.; Hartono

    2017-12-01

    Erosion modeling is an important measuring tool for both land users and decision makers to evaluate land cultivation and thus it is necessary to have a model to represent the actual reality. Erosion models are a complex model because of uncertainty data with different sources and processing procedures. Artificial neural networks can be relied on for complex and non-linear data processing such as erosion data. The main difficulty in artificial neural network training is the determination of the value of each network input parameters, i.e. hidden layer, momentum, learning rate, momentum, and RMS. This study tested the capability of artificial neural network application in the prediction of erosion risk with some input parameters through multiple simulations to get good classification results. The model was implemented in Serang Watershed, Kulonprogo, Yogyakarta which is one of the critical potential watersheds in Indonesia. The simulation results showed the number of iterations that gave a significant effect on the accuracy compared to other parameters. A small number of iterations can produce good accuracy if the combination of other parameters was right. In this case, one hidden layer was sufficient to produce good accuracy. The highest training accuracy achieved in this study was 99.32%, occurred in ANN 14 simulation with combination of network input parameters of 1 HL; LR 0.01; M 0.5; RMS 0.0001, and the number of iterations of 15000. The ANN training accuracy was not influenced by the number of channels, namely input dataset (erosion factors) as well as data dimensions, rather it was determined by changes in network parameters.

  4. Reflux disease as an etiological factor of dental erosion

    Directory of Open Access Journals (Sweden)

    Stojšin Ivana

    2010-01-01

    Full Text Available Introduction Gastroesophageal reflux is a frequent disease which has a significant influence on the development of dental erosions. Objective The aim of this research was to determine the frequency of dental erosions among the patients with gastroesophageal reflux, as well as to verify the most common symptoms of gastroesophageal disease. Methods The research comprised of two groups, each consisting of 30 patients aged 18-80 years. The experimental group comprised of patients diagnosed with gastroesophageal reflux disease (GERD, while the control group was composed of patients who were not diagnosed with GERD. Based on the illness history data, all patients of the experimental group were registered to have gastroesophageal and extraesophageal symptoms. Dental erosions were diagnosed during a stomatological inspection by using index system according to Eccles and Jenkins. Data processing was accomplished by the Statgraphics Centurion software package. Results Dental erosions were found in 76.7% of experimental group patients, and in 53.3% of control group patients. Fortynine percent of teeth of the experimental group patients and 31.1% of the control group patients showed erosive changes. On average, the number of teeth with erosions in the experimental group was 15.7 per person and in the control group 10 per person. The teeth of the front region of the upper jaw, as well as the lower first molars had the highest average value of dental erosion index. In the experimental group 12.8% of teeth and 24% of teeth in the control group were diagnosed to have dental erosion index value 1. Furthermore, 23.4% of teeth in the experimental group and 7.1% of teeth in the control group were registered to have dental erosion index value 2. Finally, the dental erosion index value 3 was found in 13.0% of teeth in the experimental group only. The highest average value of regional erosion index in the experimental group was found in the region 13-23 equalling 1

  5. Simulation of erosion in drilling tools for oil and gas industry

    Energy Technology Data Exchange (ETDEWEB)

    Arefi, B.; Settari, A. [Calgary Univ., AB (Canada); Angman, P. [Tesco Corp., Calgary, AB (Canada)

    2004-07-01

    Erosion in oil well drilling tools is a form of wear which occurs when fluid containing solid particles impacts a solid surface. The intensity of erosion is generally measured as the rate of material removal from the surface, and is expressed as E{sub r}, the weight of material removed by unit weight of impacting particles. Erosion can also be reduced by tool improvement and modification, thereby extending the life of drilling tools. To date, no attempt has been made to model the erosion phenomenon in drilling tools. This paper presents a newly developed erosion simulator which is the first design tool for the drilling industry. This work demonstrates that erosion can be simulated. A model was developed to calibrate the erosion coefficients for drilling tool conditions. The mechanism of erosion can be controlled by the impact velocity and angle. Algorithms were developed for transient simulation of the erosion of any surface in 2-dimensional geometry. The Erosion Simulator has been validated and calibrated against data provided by TESCO Corporation's casing drilling tools. The model has been shown to successfully predict and minimize erosion by modifying the tool geometry and metallurgy. 21 refs., 1 tab., 15 figs.

  6. Modelling desertification risk in the north-west of Jordan using geospatial and remote sensing techniques

    Directory of Open Access Journals (Sweden)

    Jawad T. Al-Bakri

    2016-03-01

    Full Text Available Remote sensing, climate, and ground data were used within a geographic information system (GIS to map desertification risk in the north-west of Jordan. The approach was based on modelling wind and water erosion and incorporating the results with a map representing the severity of drought. Water erosion was modelled by the universal soil loss equation, while wind erosion was modelled by a dust emission model. The extent of drought was mapped using the evapotranspiration water stress index (EWSI which incorporated actual and potential evapotranspiration. Output maps were assessed within GIS in terms of spatial patterns and the degree of correlation with soil surficial properties. Results showed that both topography and soil explained 75% of the variation in water erosion, while soil explained 25% of the variation in wind erosion, which was mainly controlled by natural factors of topography and wind. Analysis of the EWSI map showed that drought risk was dominating most of the rainfed areas. The combined effects of soil erosion and drought were reflected on the desertification risk map. The adoption of these geospatial and remote sensing techniques is, therefore, recommended to map desertification risk in Jordan and in similar arid environments.

  7. The Frequencies of Gastroesophageal and Extragastroesophageal Symptoms in Patients with Mild Erosive Esophagitis, Severe Erosive Esophagitis, and Barrett’s Esophagus in Taiwan

    Directory of Open Access Journals (Sweden)

    Sung-Shuo Kao

    2013-01-01

    Full Text Available Background. Gastroesophageal reflux disease (GERD may present with gastroesophageal and extraesophageal symptoms. Currently, the frequencies of gastroesophageal and extragastroesophageal symptoms in Asian patients with different categories of GERD remain unclear. Aim. To investigate the frequencies of gastroesophageal and extragastroesophageal symptoms in patients with mild erosive esophagitis, severe erosive esophagitis, and Barrett’s esophagus of GERD. Methods. The symptoms of symptomatic subjects with (1 Los Angeles grade A/B erosive esophagitis, (2 Los Angeles grade C/D erosive esophagitis, and (3 Barrett’s esophagus proven by endoscopy were prospectively assessed by a standard questionnaire for gastroesophageal and extragastroesophageal symptoms. The frequencies of the symptoms were compared by Chi-square test. Result. Six hundred and twenty-five patients (LA grade A/B: 534 patients; LA grade C/D: 37 patients; Barrett’s esophagus: 54 patients were assessed for gastroesophageal and extragastroesophageal symptoms. Patients with Los Angeles grade A/B erosive esophagitis had higher frequencies of symptoms including epigastric pain, epigastric fullness, dysphagia, and throat cleaning than patients with Los Angeles grade C/D erosive esophagitis. Patients with Los Angeles grade A/B erosive esophagitis also had higher frequencies of symptoms including acid regurgitation, epigastric acidity, regurgitation of food, nausea, vomiting, epigastric fullness, dysphagia, foreign body sensation of throat, throat cleaning, and cough than patients with Barrett’s esophagus. Conclusion. The frequencies of some esophageal and extraesophageal symptoms in patients with Los Angeles grade A/B erosive esophagitis were higher than those in patients with Los Angeles grade C/D erosive esophagitis and Barrett’s esophagus. The causes of different symptom profiles in different categories of GERD patients merit further investigations.

  8. Detecting Anthropogenic Disturbance on Weathering and Erosion Processes

    Science.gov (United States)

    Vanacker, V.; Schoonejans, J.; Bellin, N.; Ameijeiras-Mariño, Y.; Opfergelt, S.; Christl, M.

    2014-12-01

    Anthropogenic disturbance of natural vegetation can profoundly alter the physical, chemical and biological processes within soils. Rapid removal of topsoil during intense farming can result in an imbalance between soil production through chemical weathering and physical erosion, with direct implications on local biogeochemical cycling. However, the feedback mechanisms between soil erosion, chemical weathering and biogeochemical cycling in response to anthropogenic forcing are not yet fully understood. In this paper, we analyze dynamic soil properties for a rapidly changing anthropogenic landscape in the Spanish Betic Cordillera; and focus on the coupling between physical erosion, soil production and soil chemical weathering. Modern erosion rates were quantified through analysis of sediment deposition volumes behind check dams, and represent catchment-average erosion rates over the last 10 to 50 years. Soil production rates are derived from in-situ produced 10Be nuclide concentrations, and represent long-term flux rates. In each catchment, soil chemical weathering intensities were calculated for two soil-regolith profiles. Although Southeast Spain is commonly reported as the European region that is most affected by land degradation, modern erosion rates are low (140 t ha-1 yr-1). About 50 % of the catchments are losing soils at a rate of less than 60 t km-2 yr-1. Our data show that modern erosion rates are roughly of the same magnitude as the long-term or cosmogenically-derived erosion rates in the Betic Cordillera. Soils developed on weathered metamorphic rocks have no well-developed profile characteristics, and are generally thin and stony. Nevertheless, soil chemical weathering intensities are high; and question the occurrence of past soil truncation.

  9. CFD study of fluid flow changes with erosion

    Science.gov (United States)

    López, Alejandro; Stickland, Matthew T.; Dempster, William M.

    2018-06-01

    For the first time, a three dimensional mesh deformation algorithm is used to assess fluid flow changes with erosion. The validation case chosen is the Jet Impingement Test, which was thoroughly analysed in previous works by Hattori et al. (Kenichi Sugiyama and Harada, 2008), Gnanavelu et al. in (Gnanavelu et al., 2009, 2011), Lopez et al. in (Lopez et al., 2015) and Mackenzie et al. in (Mackenzie et al., 2015). Nguyen et al. (2014) showed the formation of a new stagnation area when the wear scar is deep enough by performing a three-dimensional scan of the wear scar after 30 min of jet impingement test. However, in the work developed here, this stagnation area was obtained solely by computational means. The procedure consisted of applying an erosion model in order to obtain a deformed geometry, which, due to the changes in the flow pattern lead to the formation of a new stagnation area. The results as well as the wear scar were compared to the results by Nguyen et al. (2014) showing the same trend. OpenFOAM® was the software chosen for the implementation of the deforming mesh algorithm as well as remeshing of the computational domain after deformation. Different techniques for mesh deformation and approaches to erosion modelling are discussed and a new methodology for erosion calculation including mesh deformation is developed. This new approach is independent of the erosion modelling approach, being applicable to both Eulerian and Lagrangian based equations for erosion calculation. Its different applications such as performance decay in machinery subjected to erosion as well as modelling of natural erosion processes are discussed here.

  10. Soil erosion in Iran: Issues and solutions

    Science.gov (United States)

    Hamidreza Sadeghi, Seyed; Cerdà, Artemi

    2015-04-01

    Iran currently faces many soil erosion-related problems (see citations below). These issues are resulted from some inherent characteristic and anthropogenic triggering forces. Nowadays, the latter plays more important rule to accelerate the erosion with further emphasis on soil erosion-prone arid and semi arid regions of the country. This contribution attempts to identify and describe the existing main reasons behind accelerated soil erosion in Iran. Appropriate solutions viz. structural and non-structural approaches will be then advised to combat or minimise the problems. Iran can be used as a pilot research site to understand the soil erosion processes in semiarid, arid and mountainous terrain and our research will review the scientific literature and will give an insight of the soil erosion rates in the main factors of the soil erosion in Iran. Key words: Anthropogenic Erosion, Land Degradation; Sediment Management; Sediment Problems Acknowledgements The research projects GL2008-02879/BTE, LEDDRA 243857 and PREVENTING AND REMEDIATING DEGRADATION OF SOILS IN EUROPE THROUGH LAND CARE (RECARE)FP7-ENV-2013- supported this research. References Aghili Nategh, N., Hemmat, A., & Sadeghi, M. (2014). Assessing confined and semi-confined compression curves of highly calcareous remolded soil amended with farmyard manure. Journal of Terramechanics, 53, 75-82. Arekhi, S., Bolourani, A. D., Shabani, A., Fathizad, H., Ahamdy-Asbchin, S. 2012. Mapping Soil Erosion and Sediment Yield Susceptibility using RUSLE, Remote Sensing and GIS (Case study: Cham Gardalan Watershed, Iran). Advances in Environmental Biology, 6(1), 109-124. Arekhi, S., Shabani, A., Rostamizad, G. 2012. Application of the modified universal soil loss equation (MUSLE) in prediction of sediment yield (Case study: Kengir Watershed, Iran). Arabian Journal of Geosciences, 5(6), 1259-1267.Sadeghi, S. H., Moosavi, V., Karami, A., Behnia, N. 2012. Soil erosion assessment and prioritization of affecting factors at plot

  11. Erosion protection of uranium tailings impoundments

    International Nuclear Information System (INIS)

    Walters, W.H.; Skaggs, R.L.; Foley, M.G.; Beedlow, P.A.

    1986-09-01

    Pacific Northwest Laboratory (PNL) prepared this report to assist in the design and review of erosion protection works for decommissioned uranium tailings impoundments. The major causes of erosion over the long-term decommissioning period are from rainfall-runoff (overland flow) and stream channel flooding. The method of protection recommended for the impoundment side slopes and site drainage channels is rock riprap. Combinations of vegetation and rock mulch are recommended for the top surface. The design methods were developed from currently available procedures supplemented by field, laboratory, and mathematical model studies performed by PNL. Guidelines for the placement of riprap, inspection, and maintenance are presented. Other subjects discussed are rock selection and testing, slope stability, and overland erosion modeling

  12. Scientific case studies in land-use driven soil erosion in the central United States: Why soil potential and risk concepts should be included in the principles of soil health

    Directory of Open Access Journals (Sweden)

    Benjamin L. Turner

    2018-03-01

    Full Text Available Despite recent improvements in overall soil health gained through conservation agriculture, which has become a global priority in agricultural systems, soil and water-related externalities (e.g., wind and water erosion continue to persist or worsen. Using an inductive, systems approach, we tested the hypothesis that such externalities persist due to expansion of cultivation onto areas unsuitable for sustained production. To test this hypothesis, a variety of data sources and analyses were used to uncover the land and water resource dynamics underlying noteworthy cases of soil erosion (either wind or water and hydrological effects (e.g., flooding, shifting hydrographs throughout the central United States. Given the evidence, we failed to reject the hypothesis that cultivation expansion is contributing to increased soil and water externalities, since significant increases in cultivation on soils with severe erosion limitations were observed everywhere the externalities were documented. We discuss the case study results in terms of land use incentives (e.g., policy, economic, and biophysical, developing concepts of soil security, and ways to utilize case studies such as those presented to better communicate the value of soil and water resource conservation. Incorporating the tenets of soil potential and soil risk into soil health evaluations and cultivation decision-making is needed to better match the soil resource with land use and help avoid more extreme soil and water-related externalities.

  13. Conceptual considerations of evaluate internal erosion phenomenon via no-erosion filter test and continuing erosion filter test

    Directory of Open Access Journals (Sweden)

    Ramos-Rivera Johnatan

    2016-01-01

    Full Text Available Some widely-graded soils may exhibit, under the influence of steady seepage flow, a behaviour in which grains of the finer fraction migrate through the interstices of the matrix formed by the coarser fraction. The migrating fines may accumulate at a downstream location within the soil. Alternatively, and where there is no capacity for retention at the downstream or exit boundary, the behaviour may lead to a washing out and consequent loss of the finer fraction. The phenomenon of erosion is termed internal instability, and the soils are considered internally unstable. Taking into consideration (i the specimen reconstitution by method of compaction, (ii the application of a vertical stress to the specimen, and (iii the use of multi-stage seepage flow with head-control, to measure the origin of a conduit through the coarser fraction, some test devices were conducted by different authors to evaluate this phenomenon, the purpose of this paper is to present some considerations and key aspects about internal erosion in dams and filter compatibility with core material (specimen reconstitution, test procedure, consolidation, seepage flow, test program and its relevance to the reality. The main reason to present this investigation is due to the absence of any specified regulatory or standard test method. Given the importance of filter compatibility of the zoned earth core dam and filter materials, as well the grading stability of each zone in the presence of seepage flow, additional consideration will be given to performing Continuing Erosion Filter (CEF tests on the core-filter interface, using the laboratory permeameter device.

  14. A combined CFD-experimental method for developing an erosion equation for both gas-sand and liquid-sand flows

    Science.gov (United States)

    Mansouri, Amir

    The surface degradation of equipment due to consecutive impacts of abrasive particles carried by fluid flow is called solid particle erosion. Solid particle erosion occurs in many industries including oil and gas. In order to prevent abrupt failures and costly repairs, it is essential to predict the erosion rate and identify the locations of the equipment that are mostly at risk. Computational Fluid Dynamics (CFD) is a powerful tool for predicting the erosion rate. Erosion prediction using CFD analysis includes three steps: (1) obtaining flow solution, (2) particle tracking and calculating the particle impact speed and angle, and (3) relating the particle impact information to mass loss of material through an erosion equation. Erosion equations are commonly generated using dry impingement jet tests (sand-air), since the particle impact speed and angle are assumed not to deviate from conditions in the jet. However, in slurry flows, a wide range of particle impact speeds and angles are produced in a single slurry jet test with liquid and sand particles. In this study, a novel and combined CFD/experimental method for developing an erosion equation in slurry flows is presented. In this method, a CFD analysis is used to characterize the particle impact speed, angle, and impact rate at specific locations on the test sample. Then, the particle impact data are related to the measured erosion depth to achieve an erosion equation from submerged testing. Traditionally, it was assumed that the erosion equation developed based on gas testing can be used for both gas-sand and liquid-sand flows. The erosion equations developed in this work were implemented in a CFD code, and CFD predictions were validated for various test conditions. It was shown that the erosion equation developed based on slurry tests can significantly improve the local thickness loss prediction in slurry flows. Finally, a generalized erosion equation is proposed which can be used to predict the erosion rate in

  15. Sediment and Cavitation Erosion Studies through Dam Tunnels

    Directory of Open Access Journals (Sweden)

    Muhammad Abid

    2016-01-01

    Full Text Available This paper presents results of sediment and cavitation erosion through Tunnel 2 and Tunnel 3 of Tarbela Dam in Pakistan. Main bend and main branch of Tunnel 2 and outlet 1 and outlet 3 of Tunnel 3 are concluded to be critical for cavitation and sediment erosion. Studies are also performed for increased sediments flow rate, concluding 5 kg/sec as the critical value for sudden increase in erosion rate density. Erosion rate is concluded to be the function of sediment flow rate and head condition. Particulate mass presently observed is reasonably low, hence presently not affecting the velocity and the flow field.

  16. Low cost sic coated erosion resistant graphite

    International Nuclear Information System (INIS)

    Zafar, M.F.; Nicholls, J.R.

    2007-01-01

    The development of materials with unique and improved properties using low cost processes is essential to increase performance and reduce cost of the solid rocket motors. Specifically advancements are needed for boost phase nozzle. As these motors operate at very high pressure and temperatures, the nozzle must survive high thermal stresses with minimal erosion to maintain performance. Currently three material choices are being exploited; which are refractory metals, graphite and carbon-carbon composites. Of these three materials graphite is the most attractive choice because of its low cost, light weight, and easy forming. However graphite is prone to erosion, both chemical and mechanical, which may affect the ballistic conditions and mechanical properties of the nozzle. To minimize this erosion high density graphite is usually preferred; which is again very expensive. Another technique used to minimize the erosion is Pyrolytic Graphite (PG) coating inside the nozzle. However PG coating is prone to cracking and spallation along with very cumbersome deposition process. Another possible methodology to avoid this erosion is to convert the inside surface of the rocket nozzle to Silicon Carbide (SiC), which is very erosion resistant and have much better thermal stability compared to graphite and even PG. Due to its functionally gradient nature such a layer will be very adherent and resistant to spallation. The current research is focused on synthesizing, characterizing and oxidation testing of such a converted SiC layer on commercial grade graphite. (author)

  17. Current and future assessments of soil erosion by water on the Tibetan Plateau based on RUSLE and CMIP5 climate models.

    Science.gov (United States)

    Teng, Hongfen; Liang, Zongzheng; Chen, Songchao; Liu, Yong; Viscarra Rossel, Raphael A; Chappell, Adrian; Yu, Wu; Shi, Zhou

    2018-04-18

    Soil erosion by water is accelerated by a warming climate and negatively impacts water security and ecological conservation. The Tibetan Plateau (TP) has experienced warming at a rate approximately twice that observed globally, and heavy precipitation events lead to an increased risk of erosion. In this study, we assessed current erosion on the TP and predicted potential soil erosion by water in 2050. The study was conducted in three steps. During the first step, we used the Revised Universal Soil Equation (RUSLE), publicly available data, and the most recent earth observations to derive estimates of annual erosion from 2002 to 2016 on the TP at 1-km resolution. During the second step, we used a multiple linear regression (MLR) model and a set of climatic covariates to predict rainfall erosivity on the TP in 2050. The MLR was used to establish the relationship between current rainfall erosivity data and a set of current climatic and other covariates. The coefficients of the MLR were generalised with climate covariates for 2050 derived from the fifth phase of the Coupled Model Intercomparison Project (CMIP5) models to estimate rainfall erosivity in 2050. During the third step, soil erosion by water in 2050 was predicted using rainfall erosivity in 2050 and other erosion factors. The results show that the mean annual soil erosion rate on the TP under current conditions is 2.76tha -1 y -1 , which is equivalent to an annual soil loss of 559.59×10 6 t. Our 2050 projections suggested that erosion on the TP will increase to 3.17tha -1 y -1 and 3.91tha -1 y -1 under conditions represented by RCP2.6 and RCP8.5, respectively. The current assessment and future prediction of soil erosion by water on the TP should be valuable for environment protection and soil conservation in this unique region and elsewhere. Copyright © 2018 Elsevier B.V. All rights reserved.

  18. Solid particle erosion of polymers and composites

    Science.gov (United States)

    Friedrich, K.; Almajid, A. A.

    2014-05-01

    After a general introduction to the subject of solid particle erosion of polymers and composites, the presentation focusses more specifically on the behavior of unidirectional carbon fiber (CF) reinforced polyetheretherketone (PEEK) composites under such loadings, using different impact conditions and erodents. The data were analyzed on the basis of a newly defined specific erosive wear rate, allowing a better comparison of erosion data achieved under various testing conditions. Characteristic wear mechanisms of the CF/PEEK composites consisted of fiber fracture, matrix cutting and plastic matrix deformation, the relative contribution of which depended on the impingement angles and the CF orientation. The highest wear rates were measured for impingement angles between 45 and 60°. Using abrasion resistant neat polymer films (in this case PEEK or thermoplastic polyurethane (TPU) ones) on the surface of a harder substrate (e.g. a CF/PEEK composite plate) resulted in much lower specific erosive wear rates. The use of such polymeric films can be considered as a possible method to protect composite surfaces from damage caused by minor impacts and erosion. In fact, they are nowadays already successfully applied as protections for wind energy rotor blades.

  19. Dental Erosion and Caries Status of Chinese University Students.

    Science.gov (United States)

    Chu, Chun Hung; Ng, Alice; Chau, Alex Man Him; Lo, Edward Chin Man

    2015-01-01

    To describe the prevalence and severity of dental erosion and caries experience of Chinese university students in Hong Kong. First-year Chinese students were invited to attend a dental clinic at a university campus in Hong Kong during their freshman orientation. A questionnaire was used to investigate the potential factors affecting their dental status, including sociodemographic factors, toothbrushing habits, dietary habits (consumption of sugary drinks), time elapsed since last dental check-up and self-perceived dental erosion status. Three calibrated dentists performed the clinical examinations. Dental erosion was evaluated using the modified Basic Erosive Wear Examination (BEWE) and dental caries experience was measured using the DMFT index. In total, 600 participants aged 18-21 were examined and 44% showed some signs of dental erosion (maximum BEWE > 0). Severe dental erosion (BEWE = 3) was found in 1% of the adults. Many (69%) had caries experience (DMFT > 0); their mean DMFT score was 2.5 ± 2.7 (± SD). The total BEWE scores were found to be associated with age and self-perception of tooth misalignment. No correlation was found between BEWE score and dietary habits, oral hygiene practices or self-perceived dental erosion status. Females, those whose last dental check-up was more than a year ago and those who perceived having dental decay or tooth wear had higher caries experience. Nearly half of the Chinese Hong Kong university students had signs of dental erosion, but very few showed signs of severe erosion. Caries experience was widespread but not high.

  20. Paradiaphyseal calcific tendinitis with cortical bone erosion.

    Science.gov (United States)

    Fritz, P; Bardin, T; Laredo, J D; Ziza, J M; D'Anglejan, G; Lansaman, J; Bucki, B; Forest, M; Kuntz, D

    1994-05-01

    To determine the clinical, radiologic, and histologic features of calcific tendinitis with cortical bone erosion. The records of 6 patients with paradiaphyseal calcific tendinitis and adjacent bone cortex erosion were reviewed. Calcific tendinitis involved the linea aspera in 4 patients, the bicipital groove in 1 patient, and the deltoid insertion in another. Calcium deposits were associated with cortical bone erosions, revealed on plain radiographs in 4 patients and computed tomography scans in 2. Bone scans were performed in 2 patients and showed local hyperfixation of the isotope. In 4 patients, suspicion of a neoplasm led to a biopsy. Calcium deposits appeared to be surrounded by a foreign body reaction with numerous giant cells. Apatite crystals were identified by transmission electron microscopy and elemental analysis in 1 surgical sample. Paradiaphyseal calcific tendinitis with cortical bone erosion is an uncommon presentation of apatite deposition disease.

  1. Quantum ensembles of quantum classifiers.

    Science.gov (United States)

    Schuld, Maria; Petruccione, Francesco

    2018-02-09

    Quantum machine learning witnesses an increasing amount of quantum algorithms for data-driven decision making, a problem with potential applications ranging from automated image recognition to medical diagnosis. Many of those algorithms are implementations of quantum classifiers, or models for the classification of data inputs with a quantum computer. Following the success of collective decision making with ensembles in classical machine learning, this paper introduces the concept of quantum ensembles of quantum classifiers. Creating the ensemble corresponds to a state preparation routine, after which the quantum classifiers are evaluated in parallel and their combined decision is accessed by a single-qubit measurement. This framework naturally allows for exponentially large ensembles in which - similar to Bayesian learning - the individual classifiers do not have to be trained. As an example, we analyse an exponentially large quantum ensemble in which each classifier is weighed according to its performance in classifying the training data, leading to new results for quantum as well as classical machine learning.

  2. Pressure and velocity dependence of flow-type cavitation erosion

    CSIR Research Space (South Africa)

    Auret, JG

    1993-12-01

    Full Text Available Previous results on the influence of water pressure and velocity on flow-type cavitations erosion, i.e. an increase in erosion rate with increasing velocity and peaking of erosion rate as a function of pressure, were confirmed by measurements with a...

  3. Optimizing land use pattern to reduce soil erosion

    Directory of Open Access Journals (Sweden)

    Reza Sokouti

    2017-01-01

    Full Text Available Soil erosion hazard is one of the main problems can affect ecological balance in watersheds. This study aimed to determine the optimal use of land to reduce erosion and increase the resident's income of Qushchi watershed in West Azerbaijan province, Iran. Income and expenses for the current land uses were calculated with field studies. Damages resulting from the soil erosion were estimated by soil depth equal to the specified land uses. For three different options including the current status of land uses without and with land management, and the standard status of land uses, multi-objective linear programming model was established by LINGO software. Then the optimization problem of the land use was solved by simplex method. Finally, the best option of land use was determined by comparing erosion rate and its cost in each scenario. Then the circumstances and the recommended conditions were compared. The results indicated that the current surface area of current land uses is not suitable to reduce erosion and increase income of residents and should change in the optimum conditions. At the optimum level, there should change horticulture area of 408 to 507 (ha, irrigated land area of 169 to 136 (ha and dry farming of 636 to 570 (ha, while conversion of rangeland area not indispensable. In addition, the results showed that in case of the optimization of land use, soil erosion and the profitability of the whole area will decrease 0.75% and increase 3.68%, respectively. In case of land management practices, soil erosion will decrease 42.27% and the profitability increase 21.39% while in the standard conditions, soil erosion will decrease 60.95% and profitability will increase 24.20%. The results of the sensitivity analysis showed that the changes in the horticulture and range land areas have the greatest impact on the increasing profitability and reducing soil erosion of Qushchi watershed. So, it is recommended using Education and Extension to promote

  4. Developing generalized parameters for post-fire erosion risk assessment using the revised Morgan-Morgan-Finney model

    NARCIS (Netherlands)

    Hosseini, Mohammadreza; Nunes, João Pedro; Pelayo, Oscar González; Keizer, Jan Jacob; Ritsema, Coen; Geissen, Violette

    2018-01-01

    Models can be useful for predicting the hydrological impacts of natural phenomenon such as wildfires and to help implement effective post-fire land management options. In this research, the revised Morgan–Morgan–Finney (MMF) model was used to simulate runoff and soil erosion in recently burned

  5. New approaches to the estimation of erosion-corrosion

    International Nuclear Information System (INIS)

    Bakirov, Murat; Ereemin, Alexandr; Levchuck, Vasiliy; Chubarov, Sergey

    2006-09-01

    Reliability safety and effectiveness of Russian and foreign power plants to a significant degree depend on erosion-corrosion durability of the equipment and pipelines, which work in single-phase and double-phase flows. Variety of failure mechanisms of metal equipment is determined phase conditions, thermodynamic, hydrodynamic, water-chemistry and other parameters of regimes. Analysis of statistic data about the damage in the main feed water pipe and of steam-water pipe and investigations in this field show, that the most of such work are fulfilled without taking into account the different mechanisms damaging the metal. Classification of failure mechanisms of metallic equipment, gave the possibility to select two groups of the destruction (failure) mechanisms of the metals: the first - which damages surface (reduction of thickness), the second - which breaks down inner structure of metals. Mechanism of erosion-corrosion of the metal is realized in single-phase and in double-phase steams (flows), and is widespread in operational circuits of NPPs. The results of erosion-corrosion influence are: reduction of thickness and as a final degree - failure of the power equipment elements, and after it failure of operational circuit of NPP. General corrosion becomes the main cause of a pollution of the working medium by the iron-containing compounds and of the deposits forming in steam generators and turbines. Local erosion-corrosion in single-phase flow can be accompanied by cavitational erosion, and in double-phase flow by drop-impact erosion. Erosion-corrosion should be understood as a physical-mechanical mechanism of destruction of the metal surface layer, accompanied, from one side, by formation of the protective oxide layer, and from the other side, by its dilution and removal into the main flow. Erosion-corrosion in the double-phase streams (flows) is a combination of the processes of corrosion and erosion components which progress at the same time. Principal feature of

  6. Plot-slope soil erosion using 7Be measurement and rill fractal dimension

    International Nuclear Information System (INIS)

    Zhang Fengbao; Yang Mingyi

    2010-01-01

    In this study, we intended to use 7 Be measurement and fractal theory to quantify soil erosion process on slope. The results showed that contribution rate of inter rill erosion was more than that of rill erosion during early stage of rainfall. When it rained, contribution rate of rill erosion began to be higher than inter rill erosion and become the main part of erosion during medium stage of rainfall. The trend of contribution rate of inter rill erosion was growing and the rill erosion was lowering during late stage of rainfall. Rill fractal dimension on the plot slope was almost growing larger during rainfall,growing quickly during early stage of rainfall and slowly during the late stage. Correlations was positive between rill fractal dimension and total erosion amount, also positive between rill fractal dimension and rill erosion. The correlations was positive between rill fractal dimension variation and total erosion amount, also was positive between rill fractal dimension variation and rill erosion amount. The best correlation was observed between rill fractal dimension and rill erosion amount. These results indicated that the rill fractal dimension on the plot slope could represent the development process of rill,the complex degree of rill and the variation of soil erosion intensity on the entire slope. (authors)

  7. Tectonic controls of Holocene erosion in a glaciated orogen

    OpenAIRE

    Adams, Byron A.; Ehlers, Todd A.

    2018-01-01

    Recent work has highlighted a strong, worldwide, glacial impact of orogen erosion rates over the last 2 Ma. While it may be assumed that glaciers increased erosion rates when active, the degree to which past glaciations influence Holocene erosion rates through the adjustment of topography is not known. In this study, we investigate the influence of long-term tectonic and post-glacial topographic controls on erosion in a glaciated orogen, the Olympic Mountains, USA. We present 14 new 10Be and ...

  8. Erosion of buffer caused by groundwater leakages

    International Nuclear Information System (INIS)

    Autio, J.; Hanana, K.; Punkkinen, O.; Koskinen, K.; Olin, M.

    2010-01-01

    Document available in extended abstract form only. In the Finnish HLW disposal concept the most important properties of the bentonite clay being considered for these isolation purposes are its thermal behaviour, low hydraulic conductivity, diffusion limited transport, rheology, plasticity, sufficient swelling potential, and exchange capacity. All of these properties depend critically on bentonite density; therefore, any potential mass loss or redistribution events must be well characterized. One such event or process is the erosion of bentonite by flowing groundwater and the groundwater flowing in newly formed channels, in special. Mechanical erosion during the operational phase, due to high groundwater pressure gradients in open excavations, has been identified as a critical issue in TKS-2006 and SR-Can. This work addresses the mechanical erosion of bentonite by fluid shear. In order for buffer erosion to occur three processes must take place: detachment, entrainment, and transport. These processes are followed by the settling of the material and redistribution of buffer mass. Erosion begins with the detachment of a particle from surrounding material, which requires the application of shear forces greater than the attractive force between the particle and parent structure. Entrainment is the process by which the eroding medium lifts the detached particle into the flow. The most important aspect in entrainment is transfer of fluid's inertial forces via surface friction to particles' inertial forces, which, in turn, must overcome the frictional resistance between the particle and its surroundings. Factors influencing frictional resistance include gravity, particle mass, saturation degree of parent structure, composition of water present in parent structure, particle size, and surface roughness. Recent erosion tests, whereby water flow was directed over compacted bentonite blocks or through a system of bentonite pellets, have indicated that bentonite erodes

  9. Dental approach to erosive tooth wear in gastroesophageal reflux ...

    African Journals Online (AJOL)

    2014-06-02

    Jun 2, 2014 ... Objective: To summarize the diagnostic protocol and treatment of dental erosion due to GERD. Methods: A Medline ..... reflux in children with cerebral palsy and its relationship to erosion of ... phate (ACP) on root surface hypersensitivity. Operative ... Lussi A. Dental erosion clinical diagnosis and case.

  10. WinDAM C earthen embankment internal erosion analysis software

    Science.gov (United States)

    Two primary causes of dam failure are overtopping and internal erosion. For the purpose of evaluating dam safety for existing earthen embankment dams and proposed earthen embankment dams, Windows Dam Analysis Modules C (WinDAM C) software will simulate either internal erosion or erosion resulting f...

  11. Change Analysis on Soil Erosion of Fujian Province from 1990 TO 2015

    Science.gov (United States)

    Wang, X. Q.; Zeng, S. J.; Chen, X. G.; Lin, J. L.; Chen, S. M.

    2017-09-01

    Soil erosion is one of major environment problems in the world, and China is one of the most serious soil erosion country. In this paper, Fujian province was used as a study area for its typical red soil region. Based on USLE model, the soil erosion modulus in 1990 and 2015 were calculated and turned to soil erosion intensity. The soil erosion distribution trend in Fujian province was decrease from south-east coastal zone to north-west inland region. In soil erosion areas, the main erosion type was light level with about 80 %, and the soil erosion levels above serious type were mainly sporadic distribution with less than 10 %. The soil erosion improved for the past 25 years. The areas of different erosion types all decreased, and the total erosion area reduced by 26.59 %. The improvement area mainly located in north-east, south and west region. The aggravation area mainly located in the north and some middle hilly regions. The impact of human activities is more significant for erosion control.

  12. Control of erosive tooth wear: possibilities and rationale

    Directory of Open Access Journals (Sweden)

    Mônica Campos Serra

    2009-06-01

    Full Text Available Dental erosion is a type of wear caused by non bacterial acids or chelation. There is evidence of a significant increase in the prevalence of dental wear in the deciduous and permanent teeth as a consequence of the frequent intake of acidic foods and drinks, or due to gastric acid which may reach the oral cavity following reflux or vomiting episodes. The presence of acids is a prerequisite for dental erosion, but the erosive wear is complex and depends on the interaction of biological, chemical and behavioral factors. Even though erosion may be defined or described as an isolated process, in clinical situations other wear phenomena are expected to occur concomitantly, such as abrasive wear (which occurs, e.g, due to tooth brushing or mastication. In order to control dental loss due to erosive wear it is crucial to take into account its multifactorial nature, which predisposes some individuals to the condition.

  13. Erosion-Oxidation Response of Boiler Grade Steels: A Mathematical Investigation

    Directory of Open Access Journals (Sweden)

    S. K. Das

    2008-01-01

    Full Text Available A ductile erosion model embodying the mechanisms of erosion involving cutting wear and repeated plastic deformation has been developed to predict erosion rates of boiler grade steels. The issue of erosion-oxidation interaction has also been addressed to further predict the mass loss resulted from this composite mechanism. A deterministic formalism for the kinetics of oxide-scale growth and a probabilistic approach to characterize the material loss are employed to describe simultaneous actions of high-temperature oxidation and mechanical erosion. The model predictions are in good agreement with the published data.

  14. Erosion on spark plug electrodes; Funkenerosion an Zuendkerzenelektroden

    Energy Technology Data Exchange (ETDEWEB)

    Rager, J.

    2006-07-01

    Durability of spark plugs is mainly determined by spark gap widening, caused by electrode wear. Knowledge about the erosion mechanisms of spark plug materials is of fundamental interest for the development of materials with a high resistance against electrode erosion. It is therefore crucial to identify those parameters which significantly influence the erosion behaviour of a material. In this work, a reliable and reproducible testing method is presented which produces and characterizes electrode wear under well-defined conditions and which is capable of altering parameters specifically. Endurance tests were carried out to study the dependence of the wear behaviour of pure nickel and platinum on the electrode temperature, gas, electrode gap, electrode diameter, atmospheric pressure, and partial pressure of oxygen. It was shown that erosion under nitrogen is negligible, irrespective of the material. This disproves all common mechanism discussed in the literature explaining material loss of spark plug electrodes. Based on this observation and the variation of the mentioned parameters a new erosion model was deduced. This relies on an oxidation of the electrode material and describes the erosion of nickel and platinum separately. For nickel, electrode wear is caused by the removal of an oxide layer by the spark. In the case of platinum, material loss occurs due to the plasma-assisted formation and subsequent evaporation of volatile oxides in the cathode spot. On the basis of this mechanism a new composite material was developed whose erosion resistance is superior to pure platinum. Oxidation resistant metal oxide particles were added to a platinum matrix, thus leading to a higher erosion resistance of the composite. However, this can be decreased by a side reaction, the separation of oxygen from the metal oxides, which effectively assists the oxidation of the matrix. This reaction can be suppressed by using highly stable oxides, characterized by a large negative Gibbs

  15. Parameters Affecting the Erosive Burning of Solid Rocket Motor

    Directory of Open Access Journals (Sweden)

    Abdelaziz Almostafa

    2018-01-01

    Full Text Available Increasing the velocity of gases inside solid rocket motors with low port-to-throat area ratios, leading to increased occurrence and severity of burning rate augmentation due to flow of propellant products across burning propellant surfaces (erosive burning, erosive burning of high energy composite propellant was investigated to supply rocket motor design criteria and to supplement knowledge of combustion phenomena, pressure, burning rate and high velocity of gases all of these are parameters affect on erosive burning. Investigate the phenomena of the erosive burning by using the 2’inch rocket motor and modified one. Different tests applied to fulfil all the parameters that calculated out from the experiments and by studying the pressure time curve and erosive burning phenomena.

  16. Numerical and experimental investigations on cavitation erosion

    Science.gov (United States)

    Fortes Patella, R.; Archer, A.; Flageul, C.

    2012-11-01

    A method is proposed to predict cavitation damage from cavitating flow simulations. For this purpose, a numerical process coupling cavitating flow simulations and erosion models was developed and applied to a two-dimensional (2D) hydrofoil tested at TUD (Darmstadt University of Technology, Germany) [1] and to a NACA 65012 tested at LMH-EPFL (Lausanne Polytechnic School) [2]. Cavitation erosion tests (pitting tests) were carried out and a 3D laser profilometry was used to analyze surfaces damaged by cavitation [3]. The method allows evaluating the pit characteristics, and mainly the volume damage rates. The paper describes the developed erosion model, the technique of cavitation damage measurement and presents some comparisons between experimental results and numerical damage predictions. The extent of cavitation erosion was correctly estimated in both hydrofoil geometries. The simulated qualitative influence of flow velocity, sigma value and gas content on cavitation damage agreed well with experimental observations.

  17. The development of U. S. soil erosion prediction and modeling

    Directory of Open Access Journals (Sweden)

    John M. Laflen

    2013-09-01

    Full Text Available Soil erosion prediction technology began over 70 years ago when Austin Zingg published a relationship between soil erosion (by water and land slope and length, followed shortly by a relationship by Dwight Smith that expanded this equation to include conservation practices. But, it was nearly 20 years before this work's expansion resulted in the Universal Soil Loss Equation (USLE, perhaps the foremost achievement in soil erosion prediction in the last century. The USLE has increased in application and complexity, and its usefulness and limitations have led to the development of additional technologies and new science in soil erosion research and prediction. Main among these new technologies is the Water Erosion Prediction Project (WEPP model, which has helped to overcome many of the shortcomings of the USLE, and increased the scale over which erosion by water can be predicted. Areas of application of erosion prediction include almost all land types: urban, rural, cropland, forests, rangeland, and construction sites. Specialty applications of WEPP include prediction of radioactive material movement with soils at a superfund cleanup site, and near real-time daily estimation of soil erosion for the entire state of Iowa.

  18. Interrill soil erosion processes on steep slopes

    Science.gov (United States)

    To date interrill erosion processes and regimes are not fully understood. The objectives are to 1) identify the erosion regimes and limiting processes between detachment and transport on steep slopes, 2) characterize the interactive effects between rainfall intensity and flow depth on sediment trans...

  19. Erosion of surface and near surface disposal facilities

    International Nuclear Information System (INIS)

    1988-06-01

    A literature search was undertaken to identify existing data and analytical procedures regarding the processes of gully erosion. The applicability of the available information to the problems of gully erosion potential at surface and near surface disposal sites is evaluated. It is concluded that the existing knowledge regarding gully erosion is insufficient to develop procedures to ensure the long-term stability of disposal sites. Recommendations for further research are presented. 46 refs

  20. Is dental erosion really a problem?

    Science.gov (United States)

    Schlueter, N; Jaeggi, T; Lussi, A

    2012-09-01

    Dental erosion is the non-carious dental substance loss induced by direct impact of exogenous or endogenous acids. It results in a loss of dental hard tissue, which can be serious in some groups, such as those with eating disorders, in patients with gastroesophageal reflux disease, and also in persons consuming high amounts of acidic drinks and foodstuffs. For these persons, erosion can impair their well-being, due to changes in appearance and/or loss of function of the teeth, e.g., the occurrence of hypersensitivity of teeth if the dentin is exposed. If erosion reaches an advanced stage, time- and money-consuming therapies may be necessary. The therapy, in turn, poses a challenge for the dentist, particularly if the defects are diagnosed at an advanced stage. While initial and moderate defects can mostly be treated non- or minimally invasively, severe defects often require complex therapeutic strategies, which often entail extensive loss of dental hard tissue due to preparatory measures. A major goal should therefore be to diagnose dental erosion at an early stage, to avoid functional and esthetic impairments as well as pain sensations and to ensure longevity of the dentition.