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.

Effects of landforms on the erosion rate in a small watershed by the {sup 137}Cs tracing method

Energy Technology Data Exchange (ETDEWEB)

Li Mian, E-mail: hnli-mian@163.co [Yellow River Institute of Hydraulic Research, Key Laboratory of Sediment Research of Yellow River of Ministry of Water Resources, Zhengzhou, Henan 450003 (China); Yao Wenyi [Yellow River Institute of Hydraulic Research, Key Laboratory of Sediment Research of Yellow River of Ministry of Water Resources, Zhengzhou, Henan 450003 (China); Li Zhanbin [Xi' an University of Technology, Xi' an, Shaanxi 710048 (China); Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi 712100 (China); Liu Puling [Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi 712100 (China); Shen Zhenzhou [Yellow River Institute of Hydraulic Research, Key Laboratory of Sediment Research of Yellow River of Ministry of Water Resources, Zhengzhou, Henan 450003 (China)

2010-05-15

It's very important to analyze and evaluate quantitatively the effects of landforms on soil erosion for the prevention and treatment of soil loss in a small watershed. The objective of this study was to evaluate the effects of landform factors on erosion rate by the {sup 137}Cs tracing method in a small watershed in the Purple Hilly Area of China. The erosion rates under different slope lengths, slope gradients and slope aspects were estimated in Xiangshuitan watershed in the Purple Hilly Area in Sichuan Basin by the {sup 137}Cs tracing method. The results showed that the erosion rate decreased exponentially with downslope distance, and it increased with increasing slope gradient during the scope of 5 deg. - 16 deg. The slope aspect had great impact on the erosion rate, and the hillside on the sunny slope had larger erosion rate than that on the shady slope, particularly for the farmland.

Long-term modeling of soil C erosion and sequestration at the small watershed scale

Energy Technology Data Exchange (ETDEWEB)

Izaurralde, R.C.; Thomson, A.M. [The Joint Global Change Research Institute, 8400 Baltimore Avenue, Suite 201, College Park, MD 20740-2496 (United States); Williams, J.R. [Blacklands Research Center, Texas A and M University, 808 East Blacklands Road, Temple, TX 76502 (United States); Post, W.M. [Oak Ridge National Laboratory, Building 1509, Bethel Valley Road, PO Box 2008 MS6335, Oak Ridge, TN 537831-6335 (United States); McGill, W.B. [College of Science and Management, University of Northern British Columbia, 3333 University Way, Prince George, BC V2N 4Z9 (Canada); Owens, L.B. [North Appalachian Experimental Watershed, USDA-Agricultural Research Station, 28850 SR 621, Coshocton, OH 43812-0488 (United States); Lal, R. [School of Natural Resources Food, Agricultural and Environmental Sciences, The Ohio State University, 422B Kottman Hall, 2021 Coffey Road, Columbus, OH 43210 (United States)

2007-01-15

The soil C balance is determined by the difference between inputs (e.g., plant litter, organic amendments, depositional C) and outputs (e.g., soil respiration, dissolved organic C leaching, and eroded C). There is a need to improve our understanding of whether soil erosion is a sink or a source of atmospheric CO2. The objective of this paper is to discover the long-term influence of soil erosion on the C cycle of managed watersheds near Coshocton, OH. We hypothesize that the amount of eroded C that is deposited in or out of a watershed compares in magnitude to the soil C changes induced via microbial respiration. We applied the erosion productivity impact calculator (EPIC) model to evaluate the role of erosion-deposition processes on the C balance of three small watersheds ({approx}1 ha). Experimental records from the USDA North Appalachian Experimental Watershed facility north of Coshocton, OH were used in the study. Soils are predominantly silt loam and have developed from loess-like deposits over residual bedrock. Management practices in the three watersheds have changed over time. Currently, watershed 118 (W118) is under a corn (Zea mays L.)-soybean (Glycine max [L.] Merr.) no till rotation, W128 is under conventional till continuous corn, and W188 is under no till continuous corn. Simulations of a comprehensive set of ecosystem processes including plant growth, runoff, and water erosion were used to quantify sediment C yields. A simulated sediment C yield of 43 {+-} 22 kg C ha{sup -1} year{sup -1} compared favorably against the observed 31 {+-} 12 kg C ha{sup -1} year{sup -1} in W118. EPIC overestimated the soil C stock in the top 30-cm soil depth in W118 by 21% of the measured value (36.8 Mg C ha{sup -1}). Simulations of soil C stocks in the other two watersheds (42.3 Mg C ha{sup -1} in W128 and 50.4 Mg C ha{sup -1} in W188) were off by <1 Mg C ha{sup -1}. Simulated eroded C re-deposited inside (30-212 kg C ha{sup -1} year{sup -1}) or outside (73{sup -1}79 kg

Estimating the erosion and deposition rates in a small watershed by the {sup 137}Cs tracing method

Energy Technology Data Exchange (ETDEWEB)

Li Mian [Yellow River Institute of Hydraulic Research, Key Laboratory of Sediment Research of Yellow River of Ministry of Water Resources, Zhengzhou, Henan 450003 (China)], E-mail: hnli-mian@163.com; Li Zhanbin [Xi' an University of Technology, Xi' an, Shaanxi 710048 (China); Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi 712100 (China); Yao Wenyi [Yellow River Institute of Hydraulic Research, Key Laboratory of Sediment Research of Yellow River of Ministry of Water Resources, Zhengzhou, Henan 450003 (China); Liu Puling [Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi 712100 (China)

2009-02-15

Understanding the erosion and deposition rates in a small watershed is important for designing soil and water conservation measures. The objective of this study is to estimate the net soil loss and gain at points with various land use types and landform positions in a small watershed in the Sichuan Hilly Basin of China by the {sup 137}Cs tracing technique. Among various land use types, the order of erosion rate was bare rock > sloping cultivated land > forest land. The paddy field and Caotu (a kind of cultivated land located at the foot of hills) were depositional areas. The erosion rate under different landform was in this order: hillside > saddle > hilltop. The footslope and the valley were depositional areas. The {sup 137}Cs technique was shown to provide an effective means of documenting the spatial distribution of soil erosion and deposition within the small watershed.

[Effects of sub-watershed landscape patterns at the upper reaches of Minjiang River on soil erosion].

Science.gov (United States)

Yang, Meng; Li, Xiu-zhen; Yang, Zhao-ping; Hu, Yuan-man; Wen, Qing-chun

2007-11-01

Based on GIS, the spatial distribution of soil loss and sediment yield in Heishui and Zhenjiangguan sub-watersheds at the upper reaches of Minjiang River was simulated by using sediment delivery-distribution (SEDD) model, and the effects of land use/cover types on soil erosion and sediment yield were discussed, based on the simulated results and related land use maps. A landscape index named location-weighted landscape contrast index (LCI) was calculated to evaluate the effects of landscape components' spatial distribution, weight, and structure of land use/cover on soil erosion. The results showed the soil erosion modulus varied with land use pattern, and decreased in the order of bare rock > urban/village > rangeland > farmland > shrub > forest. There were no significant differences in sediment yield modules among different land use/covers. In the two sub-watersheds, the spatial distribution of land use/covers on slope tended to decrease the final sediment load at watershed outlet, hut as related to relative elevation, relative distance, and flow length, the spatial distribution tended to increase sediment yield. The two sub-watersheds had different advantages as related to landscape components' spatial distribution, but, when the land use/cover weight was considered, the advantages of Zhenjiangguan sub-watershed increased. If the land use/cover structure was considered in addition, the landscape pattern of Zhenjiangguan subwatershed was better. Therefore, only the three elements, i.e., landscape components' spatial distribution, land use/cover weight, and land use/cover structure, were considered comprehensively, can we get an overall evaluation on the effects of landscape pattern on soil erosion. The calculation of LCI related to slope suggested that this index couldn' t accurately reflect the effects of land use/cover weight and structure on soil erosion, and thus, needed to be modified.

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

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Pramod Krishna, Akhouri

A watershed in Chhotanagpur plateau region was investigated utilizing space data from Indian Remote Sensing (IRS) Satellite towards spatial and temporal soil erosion process study. Geomorphologically, this plateau region is an undulating pediplain. The watershed namely Potpoto river watershed covering an area of 8160 hectares is situated in the vicinity of Ranchi, capital city of newly created Jharkahnd state. As per the national watershed atlas, Potpoto river is a tributary of Subarnarekha river system within the Upper Subarnarekha river basin under watershed no. 4H3C8. This rural to semi-urban watershed is important towards various services to Ranchi city as well as experiencing direct or indirect pressures of development. Drivers of land use changes at ground level are responsible for change in soil erosion rates in any watershed in coupled human-environment systems. This may adversely affect the soil cover of such watersheds depicted through changed rates of erosion. In a rural to semi-urban watershed like this, there are general tendencies of land use and thereby land cover changes from forests to agricultural lands, within agricultural land in terms of cropping pattern changes to cash-crops, orchards, commercial plantations and conversions to other land use categories as well towards infrastructure expansions. Universal Soil Loss Equation (USLE) was used as a basis to observe the intensity of erosion using remote sensing, rainfall data, soil data and land use/land cover map. IRS1C LISSIII and IRSP6 LISSIII data were used to identify land use status for the years 1996 and 2004 respectively. LISSIII sensor provides data in the visible to near infrared (Bands 2, 3, 4) as well as short wave infrared (Band 5) range of electromagnetic spectrum. In this study, bands 2 (0.52-0.59 microns), 3 (0.62-0.68 microns) and 4 (0.77-0.86 microns) were used with spatial resolution of 23.5 meters at nadir. Digital image processing was carried out using ERDAS Imagine software

The influence of changes in land use and landscape patterns on soil erosion in a watershed.

Science.gov (United States)

Zhang, Shanghong; Fan, Weiwei; Li, Yueqiang; Yi, Yujun

2017-01-01

It is very important to have a good understanding of the relation between soil erosion and landscape patterns so that soil and water conservation in river basins can be optimized. In this study, this relationship was explored, using the Liusha River Watershed, China, as a case study. A distributed water and sediment model based on the Soil and Water Assessment Tool (SWAT) was developed to simulate soil erosion from different land use types in each sub-basin of the Liusha River Watershed. Observed runoff and sediment data from 1985 to 2005 and land use maps from 1986, 1995, and 2000 were used to calibrate and validate the model. The erosion modulus for each sub-basin was calculated from SWAT model results using the different land use maps and 12 landscape indices were chosen and calculated to describe the land use in each sub-basin for the different years. The variations in instead of the absolute amounts of the erosion modulus and the landscape indices for each sub-basin were used as the dependent and independent variables, respectively, for the regression equations derived from multiple linear regression. The results indicated that the variations in the erosion modulus were closely related to changes in the large patch index, patch cohesion index, modified Simpson's evenness index, and the aggregation index. From the regression equation and the corresponding landscape indices, it was found that watershed erosion can be reduced by decreasing the physical connectivity between patches, improving the evenness of the landscape patch types, enriching landscape types, and enhancing the degree of aggregation between the landscape patches. These findings will be useful for water and soil conservation and for optimizing the management of watershed landscapes. Copyright © 2016 Elsevier B.V. All rights reserved.

Autonomous watersheds: Reducing flooding and stream erosion through real-time control

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Kerkez, B.; Wong, B. P.

2017-12-01

We introduce an analytical toolchain, based on dynamical system theory and feedback control, to determine how many control points (valves, gates, pumps, etc.) are needed to transform urban watersheds from static to adaptive. Advances and distributed sensing and control stand to fundamentally change how we manage urban watersheds. In lieu of new and costly infrastructure, the real-time control of stormwater systems will reduce flooding, mitigate stream erosion, and improve the treatment of polluted runoff. We discuss the how open source technologies, in the form of wireless sensor nodes and remotely-controllable valves (open-storm.org), have been deployed to build "smart" stormwater systems in the Midwestern US. Unlike "static" infrastructure, which cannot readily adapt to changing inputs and land uses, these distributed control assets allow entire watersheds to be reconfigured on a storm-by-storm basis. Our results show how the control of even just a few valves within urban catchments (1-10km^2) allows for the real-time "shaping" of hydrographs, which reduces downstream erosion and flooding. We also introduce an equivalence framework that can be used by decision-makers to objectively compare investments into "smart" system to more traditional solutions, such as gray and green stormwater infrastructure.

Comparison of WEPP and APEX runoff and erosion prediction at field scale in Goodwater Creek Experimental Watershed

Science.gov (United States)

The Water Erosion Prediction Project (WEPP) and the Agricultural Policy/Environmental eXtender (APEX) are process-based models that can predict spatial and temporal distributions of erosion for hillslopes and watersheds. This study applies the WEPP model to predict runoff and erosion for a 35-ha fie...

Investigation of Soil Erosion and Phosphorus Transport within an Agricultural Watershed

Science.gov (United States)

Klik, A.; Jester, W.; Muhar, A.; Peinsitt, A.; Rampazzo, N.; Mentler, A.; Staudinger, B.; Eder, M.

2003-04-01

In a 40 ha agricultural used watershed in Austria, surface runoff, soil erosion and nutrient losses are measured spatially distributed with 12 small erosion plots. Crops during growing season 2002 are canola, corn, sunflower, winter wheat, winter barley, rye, sugar beets, and pasture. Canopy height and canopy cover are observed in 14-day intervals. Four times per year soil water content, shear stress and random roughness of the surface are measured in a 25 x 25 m grid (140 points). The same raster is sampled for soil texture analyses and content of different phosphorus fractions in the 0-10 cm soil depth. Spatially distributed data are used for geostatistical analysis. Along three transects hydrologic conditions of the hillslope position (top, middle, foot) are investigated by measuring soil water content and soil matrix potential. After erosive events erosion features (rills, deposition, ...) are mapped using GPS. All measured data will be used as input parameters for the Limburg Soil Erosion Model (LISEM).

Assessing and Predicting Erosion from Off Highway Vehicle Trails in Front-Range Rocky Mountain Watersheds.

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Howard, M. J.; Silins, U.; Anderson, A.

2016-12-01

Off highway vehicle (OHV) trails have the potential to deliver sediment to sensitive headwater streams and increased OHV use is a growing watershed management concern in many Rocky Mountain regions. Predictive tools for estimating erosion and sediment inputs are needed to support assessment and management of erosion from OHV trail networks. The objective of this study was to a) assess erodibility (K factor) and total erosion from OHV trail networks in Rocky Mountain watersheds in south-west Alberta, Canada, and to b) evaluate the applicability of the Universal Soil Loss Equation (USLE) for predicting OHV trail erosion to support erosion management strategies. Measured erosion rates and erodibility (K) from rainfall simulation plots on OHV trails during the summers of 2014 and 2015 were compared to USLE predicted erosion from these same trails. Measured erodibility (K) from 23 rainfall simulation plots was highly variable (0.001-0.273 Mg*ha*hr/ha*MJ*mm) as was total seasonal erosion from 52 large trail sections (0.0595-43.3 Mg/ha) across trail segments of variable slope, stoniness, and trail use intensity. In particular, intensity of trail use had a large effect on both erodibility and total erosion that is not presently captured by erodibility indices (K) derived from soil characteristics. Results of this study suggest that while application of USLE for predicting erosion from OHV trail networks may be useful for initial coarse erosion assessment, a better understanding of the effect of factors such as road/trail use intensity on erodibility is needed to support use of USLE or associated erosion prediction tools for road/trail erosion management.

Identifying Watershed Regions Sensitive to Soil Erosion and Contributing to Lake Eutrophication—A Case Study in the Taihu Lake Basin (China)

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Lin, Chen; Ma, Ronghua; He, Bin

2015-01-01

Taihu Lake in China is suffering from severe eutrophication partly due to non-point pollution from the watershed. There is an increasing need to identify the regions within the watershed that most contribute to lake water degradation. The selection of appropriate temporal scales and lake indicators is important to identify sensitive watershed regions. This study selected three eutrophic lake areas, including Meiliang Bay (ML), Zhushan Bay (ZS), and the Western Coastal region (WC), as well as multiple buffer zones next to the lake boundary as the study sites. Soil erosion intensity was designated as a watershed indicator, and the lake algae area was designated as a lake quality indicator. The sensitive watershed region was identified based on the relationship between these two indicators among different lake divisions for a temporal sequence from 2000 to 2012. The results show that the relationship between soil erosion modulus and lake quality varied among different lake areas. Soil erosion from the two bay areas was more closely correlated with water quality than soil erosion from the WC region. This was most apparent at distances of 5 km to 10 km from the lake, where the r2 was as high as 0.764. Results indicate that soil erosion could be used as an indicator for identifying key watershed protection areas. Different lake areas need to be considered separately due to differences in geographical features, land use, and the corresponding effects on lake water quality. PMID:26712772

Identifying Watershed Regions Sensitive to Soil Erosion and Contributing to Lake Eutrophication--A Case Study in the Taihu Lake Basin (China).

Science.gov (United States)

Lin, Chen; Ma, Ronghua; He, Bin

2015-12-24

Taihu Lake in China is suffering from severe eutrophication partly due to non-point pollution from the watershed. There is an increasing need to identify the regions within the watershed that most contribute to lake water degradation. The selection of appropriate temporal scales and lake indicators is important to identify sensitive watershed regions. This study selected three eutrophic lake areas, including Meiliang Bay (ML), Zhushan Bay (ZS), and the Western Coastal region (WC), as well as multiple buffer zones next to the lake boundary as the study sites. Soil erosion intensity was designated as a watershed indicator, and the lake algae area was designated as a lake quality indicator. The sensitive watershed region was identified based on the relationship between these two indicators among different lake divisions for a temporal sequence from 2000 to 2012. The results show that the relationship between soil erosion modulus and lake quality varied among different lake areas. Soil erosion from the two bay areas was more closely correlated with water quality than soil erosion from the WC region. This was most apparent at distances of 5 km to 10 km from the lake, where the r² was as high as 0.764. Results indicate that soil erosion could be used as an indicator for identifying key watershed protection areas. Different lake areas need to be considered separately due to differences in geographical features, land use, and the corresponding effects on lake water quality.

Streamflow, suspended-sediment, and soil-erosion data from Kaulana and Hakioawa watersheds, Kaho'olawe, Hawai'i,

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Izuka, Scot K.; Abbott, Lyman L.

2010-01-01

Various events over the last two centuries have destroyed the vegetation and caused rapid soil erosion on large areas of the small, arid, windy tropical shield-volcano island of Kaho`olawe, Hawai`i. These activities were largely halted in the 1990s, and efforts have been made to restore the island's vegetation in order to stem erosion. In 2003, the Kaho`olawe Island Reserve Commission (KIRC) began restoration efforts using native vegetation. In 2006 to 2010, the U.S. Geological Survey (USGS), in cooperation with the KIRC, monitored streamflow, fluvial suspended-sediment transport, and erosion rates in the Hakioawa and Kaulana watersheds on northeastern Kaho`olawe to provide information needed to assess the effectiveness of restoration efforts. This report presents the results from this monitoring. Results.-Hakioawa and Kaulana gulches were dry about 90 percent of the time during the monitoring period; mean annual flow was 0.06 ft3/s at Hakioawa Gulch gage and 0.01 ft3/s at the Kaulana Gulch gage. For the period when the sediment gages on both gulches were operating concurrently (October 2007 to September 2009), sediment discharge was higher from Hakioawa Gulch than from Kaulana Gulch. The annual suspended-sediment loads for the concurrent period averaged 1,880 tons at the Hakioawa Gulch gage and 276 tons at the Kaulana Gulch gage. Of the 77 erosion-monitoring sites in the Hakioawa and Kaulana watersheds, 50 had overall rates of change indicating erosion for the monitoring period, ranging from -1 to -10 mm/yr and averaging -3 mm/yr. Seven sites had rates of change indicating overall deposition, ranging from 1 to 15 mm/yr and averaging 5 mm/yr. Twenty had rates of change below detection (less than ?1 mm/yr). The average rate of change for the 26 sites in areas that have undergone restoration by the KIRC was below the detection limit of the erosion-monitoring method. In comparison, the 51 sites in nonrestoration areas averaged -2 mm/y. Both of these averages, however

Can DEM time series produced by UAV be used to quantify diffuse erosion in an agricultural watershed?

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Pineux, N.; Lisein, J.; Swerts, G.; Bielders, C. L.; Lejeune, P.; Colinet, G.; Degré, A.

2017-03-01

Erosion and deposition modelling should rely on field data. Currently these data are seldom available at large spatial scales and/or at high spatial resolution. In addition, conventional erosion monitoring approaches are labour intensive and costly. This calls for the development of new approaches for field erosion data acquisition. As a result of rapid technological developments and low cost, unmanned aerial vehicles (UAV) have recently become an attractive means of generating high resolution digital elevation models (DEMs). The use of UAV to observe and quantify gully erosion is now widely established. However, in some agro-pedological contexts, soil erosion results from multiple processes, including sheet and rill erosion, tillage erosion and erosion due to harvest of root crops. These diffuse erosion processes often represent a particular challenge because of the limited elevation changes they induce. In this study, we propose to assess the reliability and development perspectives of UAV to locate and quantify erosion and deposition in a context of an agricultural watershed with silt loam soils and a smooth relief. Erosion and deposition rates derived from high resolution DEM time series are compared to field measurements. The UAV technique demonstrates a high level of flexibility and can be used, for instance, after a major erosive event. It delivers a very high resolution DEM (pixel size: 6 cm) which allows us to compute high resolution runoff pathways. This could enable us to precisely locate runoff management practices such as fascines. Furthermore, the DEMs can be used diachronically to extract elevation differences before and after a strongly erosive rainfall and be validated by field measurements. While the analysis for this study was carried out over 2 years, we observed a tendency along the slope from erosion to deposition. Erosion and deposition patterns detected at the watershed scale are also promising. Nevertheless, further development in the

Erosion Prediction Analysis and Landuse Planning in Gunggung Watershed, Bali, Indonesia

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Trigunasih, N. M.; Kusmawati, T.; Yuli Lestari, N. W.

2018-02-01

The purpose of this research is to predict the erosion that occurs in Gunggung watershed and sustainable landuse management plan. This research used the USLE (Universal Soil Loss Equation) methodology. The method used observation / field survey and soil analysis at the Soil Laboratory of Faculty of Agriculture, Udayana University. This research is divided into 5 stages, (1) land unit determination, (2) Field observation and soil sampling, (3) Laboratory analysis and data collection, (4) Prediction of erosion using USLE (Universal Soil Loss Equation) method, (5) The permissible erosion determination (EDP) then (6) determines the level of erosion hazard based on the depth of the soil, as well as the soil conservation plan if the erosion is greater than the allowed erosion, and (7) determining landuse management plan for sustainable agriculture. Erosion which value is smaller than soil loss tolerance can be exploited in a sustainable manner, while erosion exceeds allowable erosion will be conservation measures. Conservation action is the improvement of vegetation and land management. Land management like improvements the terrace, addition of organic matter, increase plant density, planting ground cover and planting layered header system will increase the land capability classes. Land use recommended after management is mixed plantation high density with forest plants, mix plantation high density with patio bench construction, seasonal cultivation and perennial crops, cultivation of perennial crops and cultivation of seasonal crops.

Soil erosion modeled with USLE, GIS, and remote sensing: a case study of Ikkour watershed in Middle Atlas (Morocco)

OpenAIRE

Aafaf El Jazouli; Ahmed Barakat; Abdessamad Ghafiri; Saida El Moutaki; Abderrahim Ettaqy; Rida Khellouk

2017-01-01

Abstract The Ikkour watershed located in the Middle Atlas Mountain (Morocco) has been a subject of serious soil erosion problems. This study aimed to assess the soil erosion susceptibility in this mountainous watershed using Universal Soil Loss Equation (USLE) and spectral indices integrated with Geographic Information System (GIS) environment. The USLE model required the integration of thematic factors’ maps which are rainfall aggressiveness, length and steepness of the slope, vegetation cov...

Soil erosion modeled with USLE, GIS, and remote sensing: a case study of Ikkour watershed in Middle Atlas (Morocco)

Science.gov (United States)

El Jazouli, Aafaf; Barakat, Ahmed; Ghafiri, Abdessamad; El Moutaki, Saida; Ettaqy, Abderrahim; Khellouk, Rida

2017-12-01

The Ikkour watershed located in the Middle Atlas Mountain (Morocco) has been a subject of serious soil erosion problems. This study aimed to assess the soil erosion susceptibility in this mountainous watershed using Universal Soil Loss Equation (USLE) and spectral indices integrated with Geographic Information System (GIS) environment. The USLE model required the integration of thematic factors' maps which are rainfall aggressiveness, length and steepness of the slope, vegetation cover, soil erodibility, and erosion control practices. These factors were calculated using remote sensing data and GIS. The USLE-based assessment showed that the estimated total annual potential soil loss was about 70.66 ton ha-1 year-1. This soil loss is favored by the steep slopes and degraded vegetation cover. The spectral index method, offering a qualitative evaluation of water erosion, showed different degrees of soil degradation in the study watershed according to FI, BI, CI, and NDVI. The results of this study displayed an agreement between the USLE model and spectral index approach, and indicated that the predicted soil erosion rate can be due to the most rugged land topography and an increase in agricultural areas. Indeed, these results can further assist the decision makers in implementation of suitable conservation program to reduce soil erosion.

Soil erosion and sediment fluxes analysis: a watershed study of the Ni Reservoir, Spotsylvania County, VA, USA.

Science.gov (United States)

Pope, Ian C; Odhiambo, Ben K

2014-03-01

Anthropogenic forces that alter the physical landscape are known to cause significant soil erosion, which has negative impact on surface water bodies, such as rivers, lakes/reservoirs, and coastal zones, and thus sediment control has become one of the central aspects of catchment management planning. The revised universal soil loss equation empirical model, erosion pins, and isotopic sediment core analyses were used to evaluate watershed erosion, stream bank erosion, and reservoir sediment accumulation rates for Ni Reservoir, in central Virginia. Land-use and land cover seems to be dominant control in watershed soil erosion, with barren land and human-disturbed areas contributing the most sediment, and forest and herbaceous areas contributing the least. Results show a 7 % increase in human development from 2001 (14 %) to 2009 (21.6 %), corresponding to an increase in soil loss of 0.82 Mg ha(-1) year(-1) in the same time period. (210)Pb-based sediment accumulation rates at three locations in Ni Reservoir were 1.020, 0.364, and 0.543 g cm(-2) year(-1) respectively, indicating that sediment accumulation and distribution in the reservoir is influenced by reservoir configuration and significant contributions from bedload. All three locations indicate an increase in modern sediment accumulation rates. Erosion pin results show variability in stream bank erosion with values ranging from 4.7 to 11.3 cm year(-1). These results indicate that urban growth and the decline in vegetative cover has increased sediment fluxes from the watershed and poses a significant threat to the long-term sustainability of the Ni Reservoir as urbanization continues to increase.

Watershed-scale evaluation of the Water Erosion Prediction Project (WEPP) model in the Lake Tahoe basin

Science.gov (United States)

Erin S. Brooks; Mariana Dobre; William J. Elliot; Joan Q. Wu; Jan Boll

2016-01-01

Forest managers need methods to evaluate the impacts of management at the watershed scale. The Water Erosion Prediction Project (WEPP) has the ability to model disturbed forested hillslopes, but has difficulty addressing some of the critical processes that are important at a watershed scale, including baseflow and water yield. In order to apply WEPP to...

QUANTITATIVE ESTIMATION OF SOIL EROSION IN THE DRĂGAN RIVER WATERSHED WITH THE U.S.L.E. TYPE ROMSEM MODEL

Directory of Open Access Journals (Sweden)

Csaba HORVÁTH

2008-05-01

Full Text Available Quantitative estimation of soil erosion in the Drăgan river watershed with the U.S.L.E. type Romsem modelSediment delivered from water erosion causes substantial waterway damages and water quality degradation. A number of factors such as drainage area size, basin slope, climate, land use/land cover may affect sediment delivery processes. The goal of this study is to define a computationally effective suitable soil erosion model in the Drăgan river watershed, for future sedimentation studies. Geographic Information System (GIS is used to determine the Universal Soil Loss Equation Model (U.S.L.E. values of the studied water basin. The methods and approaches used in this study are expected to be applicable in future research and to watersheds in other regions.

Forest Conversion to Land of Rubber and Palm Oil Farming and Its Effect on Run Off and Soil Erosion in Batang Pelepat Watershed

Directory of Open Access Journals (Sweden)

Sunarti

2008-09-01

Full Text Available Forest conversion to some land use happened in all watershed, includes Batang Pelepat watershed. The objectives of this research are to know effect of forest conversion to land of rubber (Hevea brasiliensis and palm oil (Elaeis guinensis Jack farming on run off and soil erosion and different of erosion rate on agro technology of rubber and palm oil farming in Batang Pelepat watershed. The research was carried out during 3 months, begin October to December 2006. Run off and soil erosion measured plot with gutter in the lower of plot. Experimental design for this research is randomized complete block design, with land use type as treatment and slope class as replication or block. Data analyzed statistically by variance analysis (F-test and Duncan New Multiple Range Test on confidence 95% (á = 0.05. The results of this research show that area of forest coverage in Batang Pelepat watershed was decreasing. In 1986 this area still 94.50% of watershed area, but in 1994 area of forest only 78.17% and in 2006 forest area 64.20% of watershed area. Forest conversion was carried out to land of rubber and palm oil farming with some actual agro technologies. Land of monoculture rubber I resulted the highest run off and soil erosion more than the other land use type and showed different of run off and soil erosion on land of secondary forest.

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

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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.

Dynamics of Soil Erosion as Influenced by Watershed Management Practices: A Case Study of the Agula Watershed in the Semi-Arid Highlands of Northern Ethiopia.

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Fenta, Ayele Almaw; Yasuda, Hiroshi; Shimizu, Katsuyuki; Haregeweyn, Nigussie; Negussie, Aklilu

2016-11-01

Since the past two decades, watershed management practices such as construction of stone bunds and establishment of exclosures have been widely implemented in the semi-arid highlands of northern Ethiopia to curb land degradation by soil erosion. This study assessed changes in soil erosion for the years 1990, 2000 and 2012 as a result of such watershed management practices in Agula watershed using the Revised Universal Soil Loss Equation. The Revised Universal Soil Loss Equation factors were computed in a geographic information system for 30 × 30 m raster layers using spatial data obtained from different sources. The results revealed significant reduction in soil loss rates by about 55 % from about 28 to 12 t ha -1 per year in 1990-2000 and an overall 64 % reduction from 28 to 10 t ha -1 per year in 1990-2012. This change in soil loss is attributed to improvement in surface cover and stone bund practices, which resulted in the decrease in mean C and P-factors, respectively, by about 19 % and 34 % in 1990-2000 and an overall decrease in C-factor by 29 % in 1990-2012. Considerable reductions in soil loss were observed from bare land (89 %), followed by cultivated land (56 %) and shrub land (49 %). Furthermore, the reduction in soil loss was more pronounced in steeper slopes where very steep slope and steep slope classes experienced over 70 % reduction. Validation of soil erosion estimations using field observed points showed an overall accuracy of 69 %, which is fairly satisfactory. This study demonstrated the potential of watershed management efforts to bring remarkable restoration of degraded semi-arid lands that could serve as a basis for sustainable planning of future developments of areas experiencing severe land degradation due to water erosion.

Floodplain trapping and cycling compared to streambank erosion of sediment and nutrients in an agricultural watershed

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Gillespie, Jaimie; Noe, Gregory; Hupp, Cliff R.; Gellis, Allen; Schenk, Edward R.

2018-01-01

Floodplains and streambanks can positively and negatively influence downstream water quality through interacting geomorphic and biogeochemical processes. Few studies have measured those processes in agricultural watersheds. We measured inputs (floodplain sedimentation and dissolved inorganic loading), cycling (floodplain soil nitrogen [N] and phosphorus [P] mineralization), and losses (bank erosion) of sediment, N, and P longitudinally in stream reaches of Smith Creek, an agricultural watershed in the Valley and Ridge physiographic province. All study reaches were net depositional (floodplain deposition > bank erosion), had high N and P sedimentation and loading rates to the floodplain, high soil concentrations of N and P, and high rates of floodplain soil N and P mineralization. High sediment, N, and P inputs to floodplains are attributed to agricultural activity in the region. Rates of P mineralization were much greater than those measured in other studies of nontidal floodplains that used the same method. Floodplain connectivity and sediment deposition decreased longitudinally, contrary to patterns in most watersheds. The net trapping function of Smith Creek floodplains indicates a benefit to water quality. Further research is needed to determine if future decreases in floodplain deposition, continued bank erosion, and the potential for nitrate leaching from nutrient-enriched floodplain soils could pose a long-term source of sediment and nutrients to downstream rivers.

Modelling streambank erosion potential using maximum entropy in a central Appalachian watershed

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J. Pitchford

2015-03-01

Full Text Available We used maximum entropy to model streambank erosion potential (SEP in a central Appalachian watershed to help prioritize sites for management. Model development included measuring erosion rates, application of a quantitative approach to locate Target Eroding Areas (TEAs, and creation of maps of boundary conditions. We successfully constructed a probability distribution of TEAs using the program Maxent. All model evaluation procedures indicated that the model was an excellent predictor, and that the major environmental variables controlling these processes were streambank slope, soil characteristics, bank position, and underlying geology. A classification scheme with low, moderate, and high levels of SEP derived from logistic model output was able to differentiate sites with low erosion potential from sites with moderate and high erosion potential. A major application of this type of modelling framework is to address uncertainty in stream restoration planning, ultimately helping to bridge the gap between restoration science and practice.

Ecohydrological Linkages, Multi-scale Processes, Temporal Variability, and Drivers of Change in a Degraded Pinyon-Juniper Watershed: Implications for Erosion Modeling

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Allen, C. D.

2006-12-01

In 1993 long-term research began on the runoff and erosion dynamics of a pinyon-juniper woodland hillslope at Bandelier National Monument in northern New Mexico (USA). In the 1.09 ha Frijolito watershed, erosion has been continuously studied at 3 spatial scales: 1 square meter, about 1000 square meters, and the entire watershed. This site is currently representative of degraded woodlands of pinyon (Pinus edulis) and one-seed juniper (Juniperus monosperma) in this region, exhibiting marked connectivity of exposed bare soil interspaces between tree canopy patches and obvious geomorphic signs of accelerated soil erosion (e.g., pedestalling, actively expanding rill networks). Ecological and land use histories show that this site has undergone a number of dramatic ecohydrological shifts since ca. C.E. 1850, transitioning from: 1) open ponderosa pine (Pinus ponderosa) overstory with limited pinyon-juniper component and substantial herbaceous understory that supported surface fires and constrained soil erosion, to; 2) ponderosa pine with reduced herbaceous cover due to livestock grazing after ca.1870, resulting in collapse of the surface fire regime and increased establishment of young pinyon and juniper trees, to; 3) mortality of all of the ponderosa pine during the extreme drought of the 1950s, leaving eroding pinyon-juniper woodland, to; 4) mortality of all mature pinyon at or above sapling size during the 2002-2003 drought, with juniper now the only dominant woody species. Detailed measurements since 1993 document high rates of soil erosion (> 2.75 Mg/ha/year on average at the watershed scale) that are rapidly stripping the local soils. Long-term observations are needed to distinguish short-term variability from longer term trends, as measurements of runoff and erosion show extreme variability at multiple time scales since 1993. The multi-scale erosion data from the Frijolito watershed reveal little dropoff in erosion rate (g/meter-squared) between the one meter

Soil erosion planning using sediment yield index method in the Nun Nadi watershed, India

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Hasan Raja Naqvi

2015-06-01

Full Text Available The study identifies the extent of soil loss and proposes a method for prioritization of micro-watershed in the Nun Nadi watershed. The study used the Sediment Yield Index (SYI method, based on weighted overlays of soil, topography, rainfall erosivity and land use parameters in 24 micro watersheds. Accordingly the values and thematic layers were integrated as per the SYI model, and minimum and maximum sediment yield values were calculated. The priority ranks as per the sediment yield values were assigned to all micro-watersheds. Then the values were classified into four priority zones according to their composite scores. Almost 14 percent area of three micro-watersheds (SW5b, SW6a and SW7b showed very high priority; approximately 30.57 percent of the study area fell under the high priority zones. These areas require immediate attention. Conservation methods are suggested, and the locations of check dams are proposed after considering drainage, slope and soil loss. Keywords: Check dam, Prioritization, Nun Nadi watershed, Soil loss, SYI

Analysis of Artificial Neural Network in Erosion Modeling: A Case Study of Serang Watershed

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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.

Soil erosion evaluation in a small watershed in Brazil through 137Cs fallout redistribution analysis and conventional models

International Nuclear Information System (INIS)

Bacchi, O.O.S.; Reichard, K.; Sparovek, G.; Ranieri, S.B.L.

2000-01-01

An investigation of rates and patterns of soil erosion on agricultural land cultivated with sugarcane was undertaken using the 137 Cs technique, USLE (Universal Soil Loss Equation) and WEPP (Water Erosion Prediction Project) model. The study was carried out on a representative catchment of a small watershed of the Piracicaba river basin, State of Sao Paulo, Brazil, called Ceveiro watershed, well known for its severe soil degradation caused by erosion. The results from the 137 Cs technique indicate that most part of the studied area (94%) are eroded at erosion rates that go up to 59 Mg ha -1 y -1 , with a weighted average rate of 23 Mg ha -1 y -1 . The weighted average rate of infield deposition and sediment retrieval that occurs in only 6% of the total area was estimated to be around 12 Mg ha -1 y -1 . These values led to very high net soil loss from the field, with rates of the order of 21 Mg ha -1 y -1 , which represents a sediment delivery ratio of 97%. A linear correlation between soil erosion rate estimated by the 137 Cs technique and the amount of available K in the top soil layer (0-20 cm) was observed. Based on this correlation the estimated amounts of net and gross K loss in the grid area due to soil erosion were of 0.2 and 1.52 kg ha -1 y -1 , respectively. The erosion rate estimated by USLE was 39 Mg ha -1 y -1 and by WEPP model 16.5 Mg ha -1 y -1 with a sediment delivery of 12.4 Mg ha -1 y -1 (75%). The results are a confirmation that the soil conservation practices adopted in the area are very poor and can explain the high siltation level of water reservoirs in the watershed. (author) [pt

Snowmelt water drives higher soil erosion than rainfall water in a mid-high latitude upland watershed

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Wu, Yuyang; Ouyang, Wei; Hao, Zengchao; Yang, Bowen; Wang, Li

2018-01-01

The impacts of precipitation and temperature on soil erosion are pronounced in mid-high latitude areas, which lead to seasonal variations in soil erosion. Determining the critical erosion periods and the reasons behind the increased erosion loads are essential for soil management decisions. Hence, integrated approaches combining experiments and modelling based on field investigations were applied to investigate watershed soil erosion characteristics and the dynamics of water movement through soils. Long-term and continuous data for surface runoff and soil erosion variation characteristics of uplands in a watershed were observed via five simulations by the Soil and Water Assessment Tool (SWAT). In addition, laboratory experiments were performed to quantify the actual soil infiltrabilities in snowmelt seasons (thawed treatment) and rainy seasons (non-frozen treatment). The results showed that over the course of a year, average surface runoff and soil erosion reached peak values of 31.38 mm and 1.46 t ha-1 a-1, respectively, in the month of April. They also ranked high in July and August, falling in the ranges of 23.73 mm to 24.91 mm and 0.55 t ha-1 a-1 to 0.59 t ha-1 a-1, respectively. With the infiltration time extended, thawed soils showed lower infiltrabilities than non-frozen soils, and the differences in soil infiltration amounts between these two were considerable. These results highlighted that soil erosion was very closely and positively correlated with surface runoff. Soil loss was higher in snowmelt periods than in rainy periods due to the higher surface runoff in early spring, and the decreased soil infiltrability in snowmelt periods contributed much to this higher surface runoff. These findings are helpful for identification of critical soil erosion periods when making soil management before critical months, especially those before snowmelt periods.

Spatial and Temporal Responses of Soil Erosion to Climate Change Impacts in a Transnational Watershed in Southeast Asia

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Pham Quy Giang

2017-03-01

Full Text Available It has been widely predicted that Southeast Asia is among the regions facing the most severe climate change impacts. Despite this forecast, little research has been published on the potential impacts of climate change on soil erosion in this region. This study focused on the impact of climate change on spatial and temporal patterns of soil erosion in the Laos–Vietnam transnational Upper Ca River Watershed. The Soil and Water Assessment Tool (SWAT coupled with downscaled global climate models (GCMs was employed for simulation. Soil erosion in the watershed was mostly found as “hill-slope erosion”, which occurred seriously in the upstream area where topography is dominated by numerous steep hills with sparse vegetation cover. However, under the impact of climate change, it is very likely that soil erosion rate in the downstream area will increase at a higher rate than in its upstream area due to a greater increase in precipitation. Seasonally, soil erosion is predicted to increase significantly in the warmer and wetter climate of the wet season, when higher erosive power of an increased amount and intensity of rainfall is accompanied by higher sediment transport capacity. The results of this study provide useful information for decision makers to plan where and when soil conservation practice should be focused.

The effectiveness of aerial hydromulch as an erosion control treatment in burned chaparral watersheds

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Pete Wohlgemuth; Jan Beyers; Pete Robichaud

2011-01-01

High severity wildfire can make watersheds susceptible to accelerated erosion, which impedes resource recovery and threatens life, property, and infrastructure in downstream human communities. Land managers often use mitigation measures on the burned hillside slopes to reduce postfire sediment fluxes. Hydromulch, a slurry of paper or wood fiber that dries to a...

Modeling of Soil Erosion by IntErO model: The Case Study of the Novsicki Potok Watershed, of the Prokletije high mountains of Montenegro

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Spalevic, Velibor; Al-Turki, Ali M.; Barovic, Goran; Leandro Naves Silva, Marx; Djurovic, Nevenka; Soares Souza, Walisson; Veloso Gomes Batista, Pedro; Curovic, Milic

2016-04-01

The application of soil conservation programs to combat erosion and sedimentation are significantly contributing to the protection of the natural resources. Watershed management practices include the assessment of Physical-Geographical, Climate, Geological, Pedological characteristics, including the analysis of Land Use of the regions concerned. The policy makers are increasingly looking for the different land uses and climatic scenarios that can be used for valuable projections for watershed management. To increase knowledge about those processes, use of hydrological and soil erosion models is needed and that is allowing quantification of soil redistribution and sediment productions. We focused on soil erosion processes in one of Northern Montenegrin mountain watersheds, the Novsicki Potok Watershed of the Polimlje River Basin, using modeling techniques: the IntErO model for calculation of runoff and soil loss. The model outcomes were validated through measurements of lake sediment deposition at the Potpec hydropower plant dam. Our findings indicate a medium potential of soil erosion risk. With 464 m³ yr-1 of annual sediment yield, corresponding to an area-specific sediment yield of 270 m³km-2 yr-1, the Novsicki Potok drainage basin belongs to the Montenegrin basins with the medium sediment discharge; according to the erosion type, it is surface erosion. The value of the Z coefficient was calculated on 0.403, what indicates that the river basin belongs to 3rd destruction category (of five). Our results suggest that the calculated peak discharge from the river basin was 82 m3s-1 for the incidence of 100 years. According to our analysis there is a possibility for large flood waves to appear in the studied river basin. With this research we, to some extent, improved the knowledge on the status of sediment yield and runoff of the river basins of Montenegro, where the map of Soil erosion is still not prepared. The IntErO model we used in this study is relatively

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

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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.

Modeling erosion and sedimentation coupled with hydrological and overland flow processes at the watershed scale

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Kim, Jongho; Ivanov, Valeriy Y.; Katopodes, Nikolaos D.

2013-09-01

A novel two-dimensional, physically based model of soil erosion and sediment transport coupled to models of hydrological and overland flow processes has been developed. The Hairsine-Rose formulation of erosion and deposition processes is used to account for size-selective sediment transport and differentiate bed material into original and deposited soil layers. The formulation is integrated within the framework of the hydrologic and hydrodynamic model tRIBS-OFM, Triangulated irregular network-based, Real-time Integrated Basin Simulator-Overland Flow Model. The integrated model explicitly couples the hydrodynamic formulation with the advection-dominated transport equations for sediment of multiple particle sizes. To solve the system of equations including both the Saint-Venant and the Hairsine-Rose equations, the finite volume method is employed based on Roe's approximate Riemann solver on an unstructured grid. The formulation yields space-time dynamics of flow, erosion, and sediment transport at fine scale. The integrated model has been successfully verified with analytical solutions and empirical data for two benchmark cases. Sensitivity tests to grid resolution and the number of used particle sizes have been carried out. The model has been validated at the catchment scale for the Lucky Hills watershed located in southeastern Arizona, USA, using 10 events for which catchment-scale streamflow and sediment yield data were available. Since the model is based on physical laws and explicitly uses multiple types of watershed information, satisfactory results were obtained. The spatial output has been analyzed and the driving role of topography in erosion processes has been discussed. It is expected that the integrated formulation of the model has the promise to reduce uncertainties associated with typical parameterizations of flow and erosion processes. A potential for more credible modeling of earth-surface processes is thus anticipated.

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

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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.

Sediment budget variation at watershed scale due to anthropogenic pressures, and its relationship to coastal erosion

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Aiello, Antonello; Adamo, Maria; Canora, Filomena

2014-05-01

The transfer of sediments from hydrographic basins towards the coast is a significant pathway of material transfer on Earth. In sedimentary environment, the main portion of sediment that enters the coastal areas is derived originally from erosion in the coastal watersheds. Extensive anthropogenic pressures carried out within coastal basins have long shown negative impacts on littoral environments. In fluvial systems, sediments trapped behind dams and in-stream gravel mining cause the reduction in sediment supply to the coast. Along the Jonian littoral of the Basilicata Region (southern Italy), natural coastal processes have been severely disrupted since the second half of the 20th century as a result of riverbed sand and gravel mining and dam construction, when economic advantages were measured in terms of the development of infrastructure, water storage, and hydropower production for the agricultural, industrial and socio-economic development of the area. Particularly, the large numbers of dams and impoundments that have been built in the hydrographic basins have led a signi?cant reduction on river sediment loads. As a result, the Jonian littoral is experiencing a catalysed erosion phenomenon. In order to increase understanding of the morpho-dynamics of the Jonian littoral environment and more fully appreciate the amount of coastal erosion, an evaluation of the sediment budget change due to dam construction within the hydrographic basins of the Basilicata Region needs to be explored. Since quantitative data on decadal trends in river sediment supply before and after dam construction are lacking, as well as updated dam silting values, river basin assessment of the spatial patterns and estimated amount of sediment erosion and deposition are important in evaluating changes in the sediment budget. As coastal areas are being affected by an increasing number of population and socio-economic activities, the amount of sediment deficit at the littoral can permit to

A Quantitative Method for Long-Term Water Erosion Impacts on Productivity with a Lack of Field Experiments: A Case Study in Huaihe Watershed, China

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Degen Lin

2016-07-01

Full Text Available Water erosion causes reduced farmland productivity, and with a longer period of cultivation, agricultural productivity becomes increasingly vulnerable. The vulnerability of farmland productivity needs assessment due to long-term water erosion. The key to quantitative assessment is to propose a quantitative method with water loss scenarios to calculate productivity losses due to long-term water erosion. This study uses the agricultural policy environmental extender (APEX model and the global hydrological watershed unit and selects the Huaihe River watershed as a case study to describe the methodology. An erosion-variable control method considering soil and water conservation measure scenarios was used to study the relationship between long-term erosion and productivity losses and to fit with 3D surface (to come up with three elements, which are time, the cumulative amount of water erosion and productivity losses to measure long-term water erosion. Results showed that: (1 the 3D surfaces fit significantly well; fitting by the 3D surface can more accurately reflect the impact of long-term water erosion on productivity than fitting by the 2D curve (to come up with two elements, which are water erosion and productivity losses; (2 the cumulative loss surface can reflect differences in productivity loss caused by long-term water erosion.

Spatial and Temporal Responses of Soil Erosion to Climate Change Impacts in a Transnational Watershed in Southeast Asia

OpenAIRE

Pham Quy Giang; Le Thi Giang; Kosuke Toshiki

2017-01-01

It has been widely predicted that Southeast Asia is among the regions facing the most severe climate change impacts. Despite this forecast, little research has been published on the potential impacts of climate change on soil erosion in this region. This study focused on the impact of climate change on spatial and temporal patterns of soil erosion in the Laos–Vietnam transnational Upper Ca River Watershed. The Soil and Water Assessment Tool (SWAT) coupled with downscaled global climate models...

Limited role for thermal erosion by turbulent lava in proximal Athabasca Valles, Mars

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Cataldo, Vincenzo; Williams, David A.; Dundas, Colin M.; Kestay, Laszlo P.

2015-01-01

The Athabasca Valles flood lava is among the most recent (Mars and was probably emplaced turbulently. The Williams et al. (2005) model of thermal erosion by lava has been applied to what we term “proximal Athabasca,” the 75 km long upstream portion of Athabasca Valles. For emplacement volumes of 5000 and 7500 km3and average flow thicknesses of 20 and 30 m, the duration of the eruption varies between ~11 and ~37 days. The erosion of the lava flow substrate is investigated for three eruption temperatures (1270°C, 1260°C, and 1250°C), and volatile contents equivalent to 0–65 vol % bubbles. The largest erosion depths of ~3.8–7.5 m are at the lava source, for 20 m thick and bubble-free flows that erupted at their liquidus temperature (1270°C). A substrate containing 25 vol % ice leads to maximum erosion. A lava temperature 20°C below liquidus reduces erosion depths by a factor of ~2.2. If flow viscosity increases with increasing bubble content in the lava, the presence of 30–50 vol % bubbles leads to erosion depths lower than those relative to bubble-free lava by a factor of ~2.4. The presence of 25 vol % ice in the substrate increases erosion depths by a factor of 1.3. Nevertheless, modeled erosion depths, consistent with the emplacement volume and flow duration constraints, are far less than the depth of the channel (~35–100 m). We conclude that thermal erosion does not appear to have had a major role in excavating Athabasca Valles.

Estimation of soil erosion for a sustainable land use planning: RUSLE model validation by remote sensing data utilization in the Kalikonto watershed

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C. Andriyanto

2015-10-01

Full Text Available Technology of Geographic Information Systems (GIS and Remote Sensing (RS are increasingly used for planning and natural resources management. GIS and RS is based on pixels is used as a tool of spatial modeling for predicting the erosion. One of the methods developed for predicting the erosion is a Revised Universal Soil Loss Equation (RUSLE. RUSLE is the method used for predicting the erosion associated with runoff gained from five parameters, namely: rain erosivity (R, soil erodibility (K, length of slopes (L, slope (S, and land management (CP. The main constraint encountered in the process of operating the GIS is the calculation of the slope length factor (L.This study was designed to create a plan of sustainable land use and low erosion through the RULSE erosion modeling by utilizing the remote sensing data. With this approach, this study was divided into three activities, namely (1 the preparation and analysis of spatial data for the determination of the parameters and estimating the erosion by using RUSLE models, (2 the validation and calibration of the model of RUSLE by measuring soil erosion at the scale of plots on the field, and (3 Creating a plan of sustainable land use and low erosion with RUSLE. The validation erosion shows the value of R2 = 0.56 and r = 0.74. Results of this study showed that the RUSLE model could be used in the Kalikonto watershed. The erosions at the value of the actual estimation, spatial Plan (RTRW and land capability class in the Kalikonto watershed were 72t / ha / year, 62 t / ha / year and 58 t / ha / year, respectively.

Usle systematization of the factors in gis to the quantification the of laminate erosion in the jirau river watershed

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Elisete Guimarães

2005-12-01

Full Text Available The present paper demonstrates the use of USLE (Universal Equation of Soil Losses in GIS (Geographic Information System as a tool for the quantification of soil losses by laminate erosion. The study area is the Jirau River watershed, which is located in the district of Dois Vizinhos, Southwestern Parana. Our results present a contribution to the development and implementation of automated methodologies focused on the characterization, quantification, and control of the laminate erosion process.

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

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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

An Establishment of Rainfall-induced Soil Erosion Index for the Slope Land in Watershed

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Tsai, Kuang-Jung; Chen, Yie-Ruey; Hsieh, Shun-Chieh; Shu, Chia-Chun; Chen, Ying-Hui

2014-05-01

With more and more concentrated extreme rainfall events as a result of climate change, in Taiwan, mass cover soil erosion occurred frequently and led to sediment related disasters in high intensity precipiton region during typhoons or torrential rain storms. These disasters cause a severely lost to the property, public construction and even the casualty of the resident in the affected areas. Therefore, we collected soil losses by using field investigation data from the upstream of watershed where near speific rivers to explore the soil erosion caused by heavy rainfall under different natural environment. Soil losses induced by rainfall and runoff were obtained from the long-term soil depth measurement of erosion plots, which were established in the field, used to estimate the total volume of soil erosion. Furthermore, the soil erosion index was obtained by referring to natural environment of erosion test plots and the Universal Soil Loss Equation (USLE). All data collected from field were used to compare with the one obtained from laboratory test recommended by the Technical Regulation for Soil and Water Conservation in Taiwan. With MATLAB as a modeling platform, evaluation model for soil erodibility factors was obtained by golden section search method, considering factors contributing to the soil erosion; such as degree of slope, soil texture, slope aspect, the distance far away from water system, topography elevation, and normalized difference vegetation index (NDVI). The distribution map of soil erosion index was developed by this project and used to estimate the rainfall-induced soil losses from erosion plots have been established in the study area since 2008. All results indicated that soil erodibility increases with accumulated rainfall amount regardless of soil characteristics measured in the field. Under the same accumulated rainfall amount, the volume of soil erosion also increases with the degree of slope and soil permeability, but decreases with the

Riparian erosion vulnerability model based on environmental features.

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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

An assessment to prioritise the critical erosion-prone sub-watersheds for soil conservation in the Gumti basin of Tripura, North-East India.

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Ahmed, Istak; Das Pan, Nibedita; Debnath, Jatan; Bhowmik, Moujuri

2017-10-31

Erosion-induced land degradation problem has emerged as a serious environmental issue across the world. Assessment of this problem through modelling can generate valuable quantitative information for the planners to identify priority areas for proper soil conservation measures. The Gumti River basin of Tripura falls under humid tropical climate and experiences soil erosion for a prolonged period which has turned into a major environmental issue. Increased sediment supply through top soil erosion is one of the major reasons for reduced navigability of this river. Thus, the present study is an attempt to prioritize the sub-watersheds of the Gumti basin by estimating soil loss through the USLE (Universal Soil Loss Equation) model. For that purpose, five parameters of the USLE model were processed, computed and overlaid in a GIS environment. The result shows that potential mean annual soil loss of the Gumti basin ranges between 0.03 and 114.08 t ha -1  year -1 . The resultant values of soil loss were classified into five categories considering the minimum and maximum values. It has been identified that low, moderate, high, very high and severe soil loss categories occupy 68.71, 8.94, 5.86, 5.02 and 11.47% of the basin respectively. Moreover, it has been recognised that sub-watersheds like SW7, SW8, SW12, SW21, SW24 and SW29 fall under very high priority class for which mitigation measures are essential. Therefore, the present study recommends mitigation measures through terrace cultivation, as an alternative of shifting cultivation in the hilly areas and through construction of check dams at the appropriate sites of the erosion prone sub-watersheds. Moreover, proper afforestation programmes that have been implemented successfully in other parts of Tripura through the Japan International Cooperation Agency, Joint Forest Management, and National Afforestation Programme should be initiated in the highly erosion-prone areas of the Gumti River basin.

Modeling and analysis of Soil Erosion processes by the River Basins model: The Case Study of the Krivacki Potok Watershed, Montenegro

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Vujacic, Dusko; Barovic, Goran; Mijanovic, Dragica; Spalevic, Velibor; Curovic, Milic; Tanaskovic, Vjekoslav; Djurovic, Nevenka

2016-04-01

The objective of this research was to study soil erosion processes in one of Northern Montenegrin watersheds, the Krivacki Potok Watershed of the Polimlje River Basin, using modeling techniques: the River Basins computer-graphic model, based on the analytical Erosion Potential Method (EPM) of Gavrilovic for calculation of runoff and soil loss. Our findings indicate a low potential of soil erosion risk, with 554 m³ yr-1 of annual sediment yield; an area-specific sediment yield of 180 m³km-2 yr-1. The calculation outcomes were validated for the entire 57 River Basins of Polimlje, through measurements of lake sediment deposition at the Potpec hydropower plant dam. According to our analysis, the Krivacki Potok drainage basin is with the relatively low sediment discharge; according to the erosion type, it is mixed erosion. The value of the Z coefficient was calculated on 0.297, what indicates that the river basin belongs to 4th destruction category (of five). The calculated peak discharge from the river basin was 73 m3s-1 for the incidence of 100 years and there is a possibility for large flood waves to appear in the studied river basin. Using the adequate computer-graphic and analytical modeling tools, we improved the knowledge on the soil erosion processes of the river basins of this part of Montenegro. The computer-graphic River Basins model of Spalevic, which is based on the EPM analytical method of Gavrilovic, is highly recommended for soil erosion modelling in other river basins of the Southeastern Europe. This is because of its reliable detection and appropriate classification of the areas affected by the soil loss caused by soil erosion, at the same time taking into consideration interactions between the various environmental elements such as Physical-Geographical Features, Climate, Geological, Pedological characteristics, including the analysis of Land Use, all calculated at the catchment scale.

Temporal and elevation trends in rainfall erosivity on a 149 km2 watershed in a semi-arid region of the American Southwest

Directory of Open Access Journals (Sweden)

Mark A. Nearing

2015-06-01

Full Text Available Temporal changes in rainfall erosivity can be expected to occur with changing climate, and because rainfall amounts are known to be in part of a function of elevation, erosivity can be expected to be influenced by elevation as well. This is particularly true in mountainous regions such as are found over much of the western United States. The objective of this study was to identify temporal and elevation trends in rainfall erosivity on a 149 km2 (58 miles2 watershed in a semi-arid region of southeastern Arizona. Data from 84 rain gages for the years 1960–2012 at elevations ranging from 1231 to 1644 m (4038–5394 ft were used in the analyses. The average annual erosivity over the watershed as a whole was 1104 MJ mm ha−1 h−1 yr−1 (65 hundreds of foot ton inch acre−1 h−1 yr−1, and ranged from approximately 950 to 1225 MJ mm ha−1 h−1 yr−1 (56–72 hundreds of foot ton inch acre−1 h−1 yr−1, with a statistical trend showing greater erosivity at the higher elevations. No statistically significant temporal changes in annual or summer erosivities were found. This result stands in contrast to recent modeling studies of runoff and erosion in the area based on downscaled GCM information that project significant levels of erosivity changes over coming decades. These results are consistent with known orographic rainfall effects, but contrast with recent studies that presented projections of significant trends of increasing erosivity in the future based on downscaled GCM outputs for the area. The results illustrate the need for testing and developing improved techniques to evaluate future erosion scenarios for purposes of making targeted soil conservation decisions. Keywords: Climate change, R-factor, RUSLE, Semiarid, Soil erosion, Walnut Gulch

Agricultural watershed modeling: a review for hydrology and soil erosion processes

Directory of Open Access Journals (Sweden)

Carlos Rogério de Mello

2016-02-01

Full Text Available ABSTRACT Models have been used by man for thousands of years to control his environment in a favorable way to better human living conditions. The use of hydrologic models has been a widely effective tool in order to support decision makers dealing with watersheds related to several economic and social activities, like public water supply, energy generation, and water availability for agriculture, among others. The purpose of this review is to briefly discuss some models on soil and water movement on landscapes (RUSLE, WEPP, GeoWEPP, LASH, DHSVM and AnnAGNPS to provide information about them to help and serve in a proper manner in order to discuss particular problems related to hydrology and soil erosion processes. Models have been changed and evaluated significantly in recent years, highlighting the use of remote sense, GIS and automatic calibration process, allowing them capable of simulating watersheds under a given land-use and climate change effects. However, hydrology models have almost the same physical structure, which is not enough for simulating problems related to the long-term effects of different land-uses. That has been our challenge for next future: to understand entirely the hydrology cycle, having as reference the critical zone, in which the hydrological processes act together from canopy to the bottom of aquifers.

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

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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.

Effects of hillslope gully stabilization on erosion and sediment production in the Torreon Wash watershed, New Mexico, 2009–12

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Matherne, Anne Marie; Tillery, Anne C.; Douglas-Mankin, Kyle R.

2018-04-10

Sediment erosion and deposition in two sets of paired (treated and untreated) upland drainages in the Torreon Wash watershed, upper Rio Puerco Basin, New Mexico, were examined over a 3 1/2-year period from spring 2009 through fall 2012. The objective was to evaluate the effectiveness of shallow, loose-stone check dams, or “one-rock dams,” as a hillslope gully erosion stabilization and mitigation method, and its potential for retaining upland eroded soils and decreasing delivery of sediment to lower ephemeral stream channels. Two high-resolution topographic surveys, completed at the beginning and end of the study period, were used to assess the effects of the mitigation measures at paired-drainage sites in both Penistaja Arroyo and Papers Wash watersheds, and at six main-stem-channel cross-section clusters along Penistaja Arroyo and Torreon Wash in the Torreon Wash watershed.For both drainage pairs, the treated drainage had greater sediment aggradation near the channel than the untreated drainage. Erosion was the dominant geomorphic process in the untreated Penistaja Arroyo drainage, whereas aggradation was the dominant process in the other three drainages. For the Penistaja Arroyo paired drainages, the treated site showed a 51-percent increase in area aggraded and 67-percent increase in volume aggraded per area analyzed over the untreated site. Both Papers Wash drainages showed net aggradation, but with similar treatment effect, with the treated site showing a 29-percent increase in area aggraded and 60-percent increase in volume aggraded per area analyzed over the untreated site. In the untreated Penistaja Arroyo drainage, the calculated minimum erosion rate was 0.0055 inches per year (in/yr; 0.14 millimeters per year [mm/yr]), whereas the calculated aggradation rates for the three drainages for which aggradation was the dominant geomorphic process were 0.0063 in/yr (0.16 mm/yr) for the Penistaja Arroyo treated drainage, 0.012 in/yr (0.31 mm/yr) for the Papers

A field method for soil erosion measurements in agricultural and natural lands

Science.gov (United States)

Y.P. Hsieh; K.T. Grant; G.C. Bugna

2009-01-01

Soil erosion is one of the most important watershed processes in nature, yet quantifying it under field conditions remains a challenge. The lack of soil erosion field data is a major factor hindering our ability to predict soil erosion in a watershed. We present here the development of a simple and sensitive field method that quantifies soil erosion and the resulting...

Estimates of soil erosion and deposition of cultivated soil of Nakhla watershed, Morocco, using 137Cs technique and calibration models

International Nuclear Information System (INIS)

Bouhlassa, S.; Moukhchane, M.; Aiachi, A.

2000-01-01

Despite the effective threat of erosion, for soil preservation and productivity in Morocco, there is still only limited information on rates of soil loss involved. This study is aimed to establish long-term erosion rates on cultivated land in the Nakhla watershed located in the north of the country, using 137 Cs technique. Two sampling strategies were adopted. The first is aimed at establishing areal estimates of erosion, whereas the second, based on a transect approach, intends to determine point erosion. Twenty-one cultivated sites and seven undisturbed sites apparently not affected by erosion or deposition were sampled to 35 cm depth. Nine cores were collected along the transect of 149 m length. The assessment of erosion rates with models varying in complexity from the simple Proportional Model to more complex Mass Balance Models which attempts to include the processes controlling the redistribution of 137 Cs in soil, enables us to demonstrate the significance of soil erosion problem on cultivated land. Erosion rates rises up to 50 t ha -1 yr -1 . The 137 Cs derived erosion rates provide a reliable representation of water erosion pattern in the area, and indicate the importance of tillage process on the redistribution of 137 Cs in soil. For aggrading sites a Constant Rate Supply (CRS) Model had been adapted and introduced to estimate easily the depositional rate. (author) [fr

[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.

Sediment sources in an urbanizing, mixed land-use watershed

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Nelson, Erin J.; Booth, Derek B.

2002-07-01

The Issaquah Creek watershed is a rapidly urbanizing watershed of 144 km 2 in western Washington, where sediment aggradation of the main channel and delivery of fine sediment into a large downstream lake have raised increasingly frequent concerns over flooding, loss of fish habitat, and degraded water quality. A watershed-scale sediment budget was evaluated to determine the relative effects of land-use practices, including urbanization, on sediment supply and delivery, and to guide management responses towards the most effective source-reduction strategies. Human activity in the watershed, particularly urban development, has caused an increase of nearly 50% in the annual sediment yield, now estimated to be 44 tonnes km -2 yr -1. The main sources of sediment in the watershed are landslides (50%), channel-bank erosion (20%), and road-surface erosion (15%). This assessment characterizes the role of human activity in mixed-use watersheds such as this, and it demonstrates some of the key processes, particularly enhanced stream-channel erosion, by which urban development alters sediment loads.

Modeling of water erosion in the watershed of the siliana KINEROS2 model

International Nuclear Information System (INIS)

Raboudi, Abir

2016-01-01

The main objective of this work is was the modeling of flowing of the surface and the solid transport within the watershed of Siliana, in the Tunisian backings, by a model which is a physically specialized KINEROS 2. This model allowed us to decide the process of interception of infiltration, flowing of the surface, and of the erosion in small agricultural or urban watershed. KINEROS2 is applied on a watershed of 1039 m 2 and of a perimeter 183,3 km on 20 years over years of observation. We are described the different steps of making use of this model which are: data preparation parameters estimations, the analyses of the principals' parameters sensibility, model calibration and its validity and the overall estimation of solid transport. The KINEROS2 application necessitates the craving of the watershed in plains and channels, which are reported in succession of the upstream towards the downstream taking into consideration the direction of the flowing of the watercourse, of the geology and of the soil occupation of the watershed. Different parameters are calculated (porosity, peak, morphological parameters of plain and channels) estimated (Manning coefficient, net effective ground conductivity) and measured on a plot (spacing, relief). Model adjusting was done on many numeric criteria, which permit to compare and appreciate stand quality, and of validity between the observed and estimated quantities. The stand of observed and estimated hydro grams was carried out learning in mind the sensibility of parameters K, G and n in the model. The model calibration gave some satisfying results highlighted by the errors that don't exceed 4 pour cent for the flow of the liquid peak and 3 pour cent for the volume of the swelling observed and calculated. For the solid transport, the stand was archived by the variation of parameters that are the most sensible (ch) and (spl). The results will be judged acceptable because the mistake doesn't exceed 1%. Sediment

Spatial analysis of soil erosion and sediment fluxes: a paired watershed study of two Rappahannock River tributaries, Stafford County, Virginia.

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Ricker, Matthew C; Odhiambo, Ben K; Church, Joseph M

2008-05-01

Soil erosion is a serious problem in areas with expanding construction, agricultural production, and improper storm water management. It is important to understand the major processes affecting sediment delivery to surficial water bodies in order to tailor effective mitigation and outreach activities. This study analyzes how naturally occurring and anthropogenic influences, such as urbanization and soil disturbance on steep slopes, are reflected in the amount of soil erosion and sediment delivery within sub-watershed-sized areas. In this study, two sub-watersheds of the Rappahannock River, Horsepen Run and Little Falls Run, were analyzed using the Revised Universal Soil Loss Equation (RUSLE) and a sediment delivery ratio (SDR) to estimate annual sediment flux rates. The RUSLE/SDR analyses for Horsepen Run and Little Falls Run predicted 298 Mg/y and 234 Mg/y, respectively, but nearly identical per-unit-area sediment flux rates of 0.15 Mg/ha/y and 0.18 Mg/ha/y. Suspended sediment sampling indicated greater amounts of sediment in Little Falls Run, which is most likely due to anthropogenic influences. Field analyses also suggest that all-terrain vehicle crossings represent the majority of sediment flux derived from forested areas of Horsepen Run. The combined RUSLE/SDR and field sampling data indicate that small-scale anthropogenic disturbances (ATV trails and construction sites) play a major role in overall sediment flux rates for both basins and that these sites must be properly accounted for when evaluating sediment flux rates at a sub-watershed scale.

Integrated process-based hydrologic and ephemeral gully modeling for better assessment of soil erosion in small watersheds

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Sheshukov, A. Y.; Karimov, V. R.

2017-12-01

Excessive soil erosion in agriculturally dominated watersheds causes degradation of arable land and affects agricultural productivity. Structural and soil-quality best management practices can be beneficial in reducing sheet and rill erosion, however, larger rills, ephemeral gullies, and concentrated flow channels still remain to be significant sources of sediment. A better understanding of channelized soil erosion, underlying physical processes, and ways to mitigate the problem is needed to develop innovative approaches for evaluation of soil losses from various sediment sources. The goal of this study was to develop a novel integrated process-based catchment-scale model for sheet, rill, and ephemeral gully erosion and assess soil erosion mitigation practices. Geospatially, a catchment was divided into ephemeral channels and contributing hillslopes. Surface runoff hydrograph and sheet-rill erosion rates from contributing hillslopes were calculated based on the Water Erosion Prediction Project (WEPP) model. For ephemeral channels, a dynamic ephemeral gully erosion model was developed. Each channel was divided into segments, and channel flow was routed according to the kinematic wave equation. Reshaping of the channel profile in each segment (sediment deposition, soil detachment) was simulated at each time-step according to acting shear stress distribution along the channel boundary and excess shear stress equation. The approach assumed physically-consistent channel shape reconfiguration representing channel walls failure and deposition in the bottom of the channel. Soil erodibility and critical shear stress parameters were dynamically adjusted due to seepage/drainage forces based on computed infiltration gradients. The model was validated on the data obtained from the field study by Karimov et al. (2014) yielding agreement with NSE coefficient of 0.72. The developed model allowed to compute ephemeral gully erosion while accounting for antecedent soil moisture

Spatial variability of sediment erosion processes using GIS analysis within watersheds in a historically mined region, Patagonia Mountains, Arizona

Science.gov (United States)

Brady, Laura M.; Gray, Floyd; Wissler, Craig A.; Guertin, D. Phillip

2001-01-01

In this study, a geographic information system (GIS) is used to integrate and accurately map field studies, information from remotely sensed data, watershed models, and the dispersion of potentially toxic mine waste and tailings. The purpose of this study is to identify erosion rates and net sediment delivery of soil and mine waste/tailings to the drainage channel within several watershed regions to determine source areas of sediment delivery as a method of quantifying geo-environmental analysis of transport mechanisms in abandoned mine lands in arid climate conditions. Users of this study are the researchers interested in exploration of approaches to depicting historical activity in an area which has no baseline data records for environmental analysis of heavily mined terrain.

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.

Modeling of phosphorus fluxes produced by wild fires at watershed scales.

Science.gov (United States)

Matyjasik, M.; Hernandez, M.; Shaw, N.; Baker, M.; Fowles, M. T.; Cisney, T. A.; Jex, A. P.; Moisen, G.

2017-12-01

River runoff is one of the controlling processes in the terrestrial phosphorus cycle. Phosphorus is often a limiting factor in fresh water. One of the factors that has not been studied and modeled in detail is phosporus flux produced from forest wild fires. Phosphate released by weathering is quickly absorbed in soils. Forest wild fires expose barren soils to intensive erosion, thus releasing relatively large fluxes of phosphorus. Measurements from three control burn sites were used to correlate erosion with phosphorus fluxes. These results were used to model phosphorus fluxes from burned watersheds during a five year long period after fires occurred. Erosion in our model is simulated using a combination of two models: the WEPP (USDA Water Erosion Prediction Project) and the GeoWEPP (GIS-based Water Erosion Prediction Project). Erosion produced from forest disturbances is predicted for any watershed using hydrologic, soil, and meteorological data unique to the individual watersheds or individual slopes. The erosion results are modified for different textural soil classes and slope angles to model fluxes of phosphorus. The results of these models are calibrated using measured concentrations of phosphorus for three watersheds located in the Interior Western United States. The results will help the United States Forest Service manage phosporus fluxes in national forests.

Rapid Erosion Modeling in a Western Kenya Watershed using Visible Near Infrared Reflectance, Classification Tree Analysis and 137Cesium.

Science.gov (United States)

deGraffenried, Jeff B; Shepherd, Keith D

2009-12-15

Human induced soil erosion has severe economic and environmental impacts throughout the world. It is more severe in the tropics than elsewhere and results in diminished food production and security. Kenya has limited arable land and 30 percent of the country experiences severe to very severe human induced soil degradation. The purpose of this research was to test visible near infrared diffuse reflectance spectroscopy (VNIR) as a tool for rapid assessment and benchmarking of soil condition and erosion severity class. The study was conducted in the Saiwa River watershed in the northern Rift Valley Province of western Kenya, a tropical highland area. Soil 137 Cs concentration was measured to validate spectrally derived erosion classes and establish the background levels for difference land use types. Results indicate VNIR could be used to accurately evaluate a large and diverse soil data set and predict soil erosion characteristics. Soil condition was spectrally assessed and modeled. Analysis of mean raw spectra indicated significant reflectance differences between soil erosion classes. The largest differences occurred between 1,350 and 1,950 nm with the largest separation occurring at 1,920 nm. Classification and Regression Tree (CART) analysis indicated that the spectral model had practical predictive success (72%) with Receiver Operating Characteristic (ROC) of 0.74. The change in 137 Cs concentrations supported the premise that VNIR is an effective tool for rapid screening of soil erosion condition.

Modelling soil erosion potential in the transboundary (Kenya & Tanzania) catchment of river Umba using remotely sensed data

NARCIS (Netherlands)

Koedam, N.; Mutisya, B.; Kairo, J.; Resink-Ndungu, Jane Njeri; Kervyn, M.

2017-01-01

Soil erosion is one of the leading forms of soil degradation. Estimating soil erosion from field measurements is expensive hence the extent of soil erosion in many tropical watersheds is unknown. Erosion is a complex process; some of the eroded materials are deposited within the watershed while the

Use of USLE/GIS methodology for predicting soil loss in a semiarid agricultural watershed.

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Erdogan, Emrah H; Erpul, Günay; Bayramin, Ilhami

2007-08-01

The Universal Soil Loss Equation (USLE) is an erosion model to estimate average soil loss that would generally result from splash, sheet, and rill erosion from agricultural plots. Recently, use of USLE has been extended as a useful tool predicting soil losses and planning control practices in agricultural watersheds by the effective integration of the GIS-based procedures to estimate the factor values in a grid cell basis. This study was performed in the Kazan Watershed located in the central Anatolia, Turkey, to predict soil erosion risk by the USLE/GIS methodology for planning conservation measures in the site. Rain erosivity (R), soil erodibility (K), and cover management factor (C) values of the model were calculated from erosivity map, soil map, and land use map of Turkey, respectively. R values were site-specifically corrected using DEM and climatic data. The topographical and hydrological effects on the soil loss were characterized by LS factor evaluated by the flow accumulation tool using DEM and watershed delineation techniques. From resulting soil loss map of the watershed, the magnitude of the soil erosion was estimated in terms of the different soil units and land uses and the most erosion-prone areas where irreversible soil losses occurred were reasonably located in the Kazan watershed. This could be very useful for deciding restoration practices to control the soil erosion of the sites to be severely influenced.

Soil erosion determination in an watershed from Northern Parana (Brazil) using 137Cs

International Nuclear Information System (INIS)

Andrello, Avacir Casanova; Appoloni, Carlos Roberto; Guimaraes, Maria de Fatima

2004-01-01

The objective of this work was study the soil losses or gains in a watershed in the municipal district of Ca mbe, P R, Brazil using 137 Cs as marker for the determination of soil redistributions. A transect sampling was used to evaluate the influence of different tillage on soil erosion. One point, located in a forest area was sampled and analyzed to determine the reference inventory of cesium-137 deposited by fallout. The average value of the reference inventory was 292 Bq m -2 . The cesium-137 inventory of the transect samples varied from 80 Bq m -2 to 403 Bq m -2 . The sampling points in pasture presented soil losses. The sampling points in coffee plantation did not present losses or gains. The sampling points in soybean cultivated areas presented soil losses. (author)

18 CFR 801.9 - Watershed management.

Science.gov (United States)

2010-04-01

... 18 Conservation of Power and Water Resources 2 2010-04-01 2010-04-01 false Watershed management... GENERAL POLICIES § 801.9 Watershed management. (a) The character, extent, and quality of water resources... management including soil and water conservation measures, land restoration and rehabilitation, erosion...

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.

Whole Watershed Quantification of Net Carbon Fluxes by Erosion and Deposition within the Christina River Basin Critical Zone Observatory

Science.gov (United States)

Aufdenkampe, A. K.; Karwan, D. L.; Aalto, R. E.; Marquard, J.; Yoo, K.; Wenell, B.; Chen, C.

2013-12-01

We have proposed that the rate at which fresh, carbon-free minerals are delivered to and mix with fresh organic matter determines the rate of carbon preservation at a watershed scale (Aufdenkampe et al. 2011). Although many studies have examined the role of erosion in carbon balances, none consider that fresh carbon and fresh minerals interact. We believe that this mechanism may be a dominant sequestration process in watersheds with strong anthropogenic impacts. Our hypothesis - that the rate of mixing fresh carbon with fresh, carbon-free minerals is a primary control on watershed-scale carbon sequestration - is central to our Christina River Basin Critical Zone Observatory project (CRB-CZO, http://www.udel.edu/czo/). The Christina River Basin spans 1440 km2 from piedmont to Atlantic coastal plain physiographic provinces in the states of Pennsylvania and Delaware, and experienced intensive deforestation and land use beginning in the colonial period of the USA. Here we present a synthesis of multi-disciplinary data from the CRB-CZO on materials as they are transported from sapprolite to topsoils to colluvium to suspended solids to floodplains, wetlands and eventually to the Delaware Bay estuary. At the heart of our analysis is a spatially-integrated, flux-weighted comparison of the organic carbon to mineral surface area ratio (OC/SA) of erosion source materials versus transported and deposited materials. Because source end-members - such as forest topsoils, farmed topsoils, gullied subsoils and stream banks - represent a wide distribution of initial, pre-erosion OC/SA, we quantify source contributions using geochemical sediment fingerprinting approaches (Walling 2005). Analytes used for sediment fingerprinting include: total mineral elemental composition (including rare earth elements), fallout radioisotope activity for common erosion tracers (beryllium-7, beryllium-10, lead-210, cesium-137), particle size distribution and mineral specific surface area, in addition

Potencial de erosão da bacia do Rio Uberaba Potential of erosion in Uberaba River watershed

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Renato F. do Valle Júnior

2010-10-01

Full Text Available Este trabalho teve por objetivo identificar qualitativamente as áreas suscetíveis à erosão laminar na bacia do Rio Uberaba, localizada em Uberaba -MG, apoiado no modelo matemático da Equação Universal de Perda de Solo (EUPS. Foram utilizadas cartas de: solos, uso e ocupação das terras, redes de drenagem, declividade e dados pluviográficos, utilizando-se de um Sistema de Informação Geográfica (SIG -IDRISI. A espacialização do potencial de erosão só foi possível a partir da estimativa da tolerância às perdas laminares para cada tipo de solo da bacia, e da profundidade dos solos, por entender que as perdas são mais significativas em solos mais rasos do que em solos muito profundos. Na análise dos resultados, verificou-se que 37% da área total da bacia do Rio Uberaba (905,24 km² sofrem perdas de solos acima do limite de tolerância, sendo 12% em solos profundos e 25% em muito profundos, e a espacialização deste evento favorece a adoção de ações efetivas quanto à conservação dos solos da bacia.This work aimed to identify qualitatively the areas susceptive to laminar erosion in Uberaba river watershed, located in Uberaba-MG, Brazil, based on the mathematical model of the Universal Soil Loss Equation (USLE. The following maps had been used: soil, land use, drainage net, slope and rainfall data, using a Geographic Information System (GIS - IDRISI to analyze and manage the data that are linked to the location. The spatiality of the potential of erosion was possible from the estimative of the tolerance to laminar losses for each kind of soil in the watershed and soil depth, to understand that the losses are more significant in flatter soil than in very deep ones. In the analysis of the results, it was verified that 37% of the total area of the watershed of the Uberaba river (905,24 km² showed losses above the tolerance limit, being 12% in deep soil and 25% in very deeply ones, and the spatiality of this event, regards to

Evaluation of the potential for erosion and its relationship with the rain energy in the river of Santa Rosa watershed, Costa Rica; Evaluacion del potential erosivo y su relacion con la energia de la lluvia en la microcuenca del rio Santa Rosa, Costa Rica

Energy Technology Data Exchange (ETDEWEB)

Acuna Chinchilla, Sisgo R; Aguilar Pereira, Jose F. [Universidad de Costa Rica (Costa Rica). Escuela de Ingenieria Agricola], E-mail: rachith2001@yahoo.esa

2010-07-01

Costa Rica like rest of the world, erosion has negative effects on agricultural production systems and hydroelectric power. In a country where 95% of energy is produced by hydroelectric plants, the management of watersheds is essential where there are hydro projects. This study evaluates the potential erosion of the watershed of the Rio Santa Rosa, (10445 ha) in Guanacaste, Costa Rica, which supplies sediment to the Santa Rosa and Sandillal dams. The evaluation places were defined using aerial photography GIS and GPS tools. The sediment was measured through 19 experimental plots in two land uses (pasture and forest) and three slope ranges (0-15%, 15-30%, 30-45%). The energy was determined on erosive rains comparing the mass of sediment collected. The most vulnerable areas were identified, to define appropriate mitigation measures. It was found that the forest generates more erosion than grass. Furthermore, under similar conditions of coverage, an increase in the range of slopes, erosion increases between two and six times, a direct relationship exists between energy and erosion in the way that coverage is reduced. It was generated a vulnerability map for the watershed. (author)

Return on investment from fuel treatments to reduce severe wildfire and erosion in a watershed investment program in Colorado.

Science.gov (United States)

Jones, Kelly W; Cannon, Jeffery B; Saavedra, Freddy A; Kampf, Stephanie K; Addington, Robert N; Cheng, Antony S; MacDonald, Lee H; Wilson, Codie; Wolk, Brett

2017-08-01

A small but growing number of watershed investment programs in the western United States focus on wildfire risk reduction to municipal water supplies. This paper used return on investment (ROI) analysis to quantify how the amounts and placement of fuel treatment interventions would reduce sediment loading to the Strontia Springs Reservoir in the Upper South Platte River watershed southwest of Denver, Colorado following an extreme fire event. We simulated various extents of fuel mitigation activities under two placement strategies: (a) a strategic treatment prioritization map and (b) accessibility. Potential fire behavior was modeled under each extent and scenario to determine the impact on fire severity, and this was used to estimate expected change in post-fire erosion due to treatments. We found a positive ROI after large storm events when fire mitigation treatments were placed in priority areas with diminishing marginal returns after treating >50-80% of the forested area. While our ROI results should not be used prescriptively they do show that, conditional on severe fire occurrence and precipitation, investments in the Upper South Platte could feasibly lead to positive financial returns based on the reduced costs of dredging sediment from the reservoir. While our analysis showed positive ROI focusing only on post-fire erosion mitigation, it is important to consider multiple benefits in future ROI calculations and increase monitoring and evaluation of these benefits of wildfire fuel reduction investments for different site conditions and climates. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hillslope erosion and hydrologic response in two small watersheds in Yosemite National Park following the 2013 Rim Fire, CA

Science.gov (United States)

Kuhn, T. J.; Forrester, H.; Abney, R.; DeLong, S.; Roche, J. W.; Asefaw Berhe, A.

2016-12-01

The 2013 Rim Fire burned 1036 km2 in the Sierra Nevada, including 312 km2 within Yosemite National Park, and generated concern about post-fire effects in the Tuolumne River watershed. We evaluated hillslope erosion and water quality during the winter storm seasons of 2013-2015, in two small watersheds (3.0 and 3.6 km2) in Yosemite located within the rain-snow transition zone. Within a month of fire containment, we installed equipment to monitor streamflow, rainfall, turbidity, and total suspended solids during storms. On moderate and high severity burn areas (based on initial dNBR data), we established 21 plots (100-150 m2) to trap all sediment (≥ silt size) eroded from moderate to steep (11°-26°) slopes. Soil temperature sensors were installed at 14 plots to measure the presence of snow cover. Lastly, we conducted seven terrestrial lidar surveys to measure vegetation recovery and topographic change. In the three study years, precipitation intensity events were generally low and lacked more typical higher intensity storms (I-30 in mm: Min = 1.5; Max = 34.0; Median = 6.1). Preliminary results suggest that despite revegetation, a lack of intense storms during the 1st and 2nd years following the fire produced less suspended solids in streams than the 3rd year. Hillslope erosion in plots was controlled by burn severity, with moderate severity plots having significantly more transport of coarse material (>2mm, mainly litterfall) and high severity plots having significantly more fine material (geologic parent material; a topic of current analyses. The dominant surface processes revealed by lidar were sheetflow and minor rill formation in the plots, and rilling and gully erosion on slopes near the plots. Analyses of sediment produced from snow storms, or those with pre-existing snow cover, indicate sediment export is dampened by these conditions, and allow for partitioning of within-channel and hillslope sediment sources. Overall, initial analyses suggest that

Prioritization of catchments based on soil erosion using remote sensing and GIS.

Science.gov (United States)

Khadse, Gajanan K; Vijay, Ritesh; Labhasetwar, Pawan K

2015-06-01

Water and soil are the most essential natural resources for socioeconomic development and sustenance of life. A study of soil and water dynamics at a watershed level facilitates a scientific approach towards their conservation and management. Remote sensing and Geographic Information System are tools that help to plan and manage natural resources on watershed basis. Studies were conducted for the formulation of catchment area treatment plan based on watershed prioritization with soil erosion studies using remote sensing techniques, corroborated with Geographic Information System (GIS), secondary data and ground truth information. Estimation of runoff and sediment yield is necessary in prioritization of catchment for the design of soil conservation structures and for identifying the critical erosion-prone areas of a catchment for implementation of best management plan with limited resources. The Universal Soil Loss Equation, Sediment Yield Determination and silt yield index methods are used for runoff and soil loss estimation for prioritization of the catchments. On the basis of soil erosion classes, the watersheds were grouped into very high, high, moderate and low priorities. High-priority watersheds need immediate attention for soil and water conservation, whereas low-priority watershed having good vegetative cover and low silt yield index may not need immediate attention for such treatments.

Optimizing land use pattern to reduce soil erosion

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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

Redistribution of cesium-137 in southeastern watersheds

International Nuclear Information System (INIS)

McHenry, J.R.; Ritchie, J.C.

1975-01-01

Sediment samples from 14 southeastern agricultural reservoirs and surface samples from representative soils from the contributing water shed areas were analyzed for 137 Cs. The concentrations of 137 Cs measured reflect the nature of the watershed, its cover, its use, and man's activities. Since the redistribution of 137 Cs was assumed to result from soil erosion, recent erosion rates can be calculated from the measured 137 Cs accumulations in sediments and from the decreases in the 137 Cs calculated to have been deposited on upland soils. Measured concentrations of 137 Cs ranged from 14 to 158 nCi/m 2 in surface soils. As much as 525 nCi/m 2 of 137 Cs was measured in the deposited sediment profile. Watershed budgets for 137 Cs were calculated for three representative watersheds using available sediment survey information and the measured 137 Cs concentrations

Soil erosion from harvested sites versus streamside management zone sediment deposition in the Piedmont of Virginia

Science.gov (United States)

William A. Lakel; W. Michael Aust; C. Andrew Dolloff; Amy W. Easterbrook

2006-01-01

Forestry best management practices were primarily developed to address two major issues related to soil erosion: water quality and site productivity. Sixteen watersheds managed as loblolly pine plantations in the piedmont region were monitored for soil erosion and water quality prior to treatment. Subsequently, all watersheds were harvested with clearcutting, ground-...

Quantifying Hillslope to Watershed Erosional Response Following Wildfire

Science.gov (United States)

Vega, S.; Pierson, F. B.; Williams, C. J.; Brooks, E. S.; Strand, E. K.; Seyfried, M. S.; Murdock, M.; Pierce, J. L.; Roehner, C.; Lindsay, K.; Robichaud, P. R.; Brown, R. E.

2017-12-01

Across the western US, wildfires in sagebrush vegetation are occurring at a more frequent rate and higher severity. This has resulted in a decline of sagebrush rangeland. The changing fire regime can be attributed to invasive plant species and warming climate conditions. As the result of wildfire, protective vegetation cover is removed leaving the soil bare and exposed to erosion. Erosion following wildfire is a main concern among land managers due to the threat it poses to resources, infrastructure, and human health. Numerous studies have used artificial rainfall to assess post-fire runoff and erosion and rehabilitation treatment effectiveness. These results have found that high intensity rain events typical of summer convective storms drive post-fire erosion. The purpose of this study is to improve scientific understanding of how site-specific physical and biological attributes affect hillslope to watershed scale sediment yield on a mountainous burned sagebrush landscape. This study uses natural rainfall and a network of silt fences to quantify hillslope to watershed scale erosion response. The erosional drivers over various spatial scales were evaluated in context with vegetation recovery for a 2 year post-fire period. A network of silt fences was installed over long and short hillslope distances and in swales within the 130 ha Murphy Creek catchment in the Reynolds Creek Experimental Watershed in southwestern Idaho. We evaluated: 1) vegetation, soils, and sediment delivery across multiple spatial scales associated with 30 silt fences spanning north and south facing aspects, 2) precipitation input at two meteorological stations, and 3) watershed streamflow and sediment discharge from an existing weir. During the first and second year post-fire, the swales on both aspects produced more sediment than the short and long hillslopes. The results suggest that significant amounts of sediment and organic matter were deposited in the swales creating drifts. Sediment

The use of stakeholder analysis in integrated watershed management

NARCIS (Netherlands)

Mutekanga, F.P.; Kessler, A.; Leber, K.; Visser, S.M.

2013-01-01

In the Ngenge watershed, at Mt. Elgon in the eastern Ugandan highlands, agricultural practices cause serious soil erosion problems and subsequent decrease in soil and water quality. Attempts to manage soil erosion through policy interventions have not been successful, because existing policies and

Effects of roads and well pads on erosion in the Largo Canyon watershed, New Mexico, 2001-02

Science.gov (United States)

Matherne, Anne Marie

2006-01-01

Largo Canyon, located in the San Juan Basin of northwestern New Mexico, is one of the longest dry washes in the world. Oil and gas production in the San Juan Basin, which began in the 1940's, required the development of an extensive network of dirt roads to service the oil and gas wells in the Navajo Reservoir area. Presently, there are about eight wells per square mile, and the density of oil and gas wells is expected to increase. Potential environmental effects on landscape stability that may result from the additional roads and well pads have not been documented. In 2001, the U.S. Geological Survey began a study in cooperation with the Bureau of Land Management to evaluate the effects of roads and well pads associated with oil and gas operations on the erosion potential of Bureau of Land Management lands in the Largo Canyon watershed. The effects of roads and well pads on erosion were quantified by installing sediment dams (dams) and by surveying transects across roads and well pads. Data from 26 dams were used in the analysis. Dams were installed at 43 sites: 21 on hillsides upslope from roads or pads to measure erosion from hillslopes, 11 at the downslope edges of roads to measure erosion from roads, and 11 at the downslope edges of well pads to measure erosion from well pads. Pairs of survey transects were established at nine well pads and two road locations. Sediment-accumulation data for 26 dams, recorded at 17 measurement intervals, indicate that average erosion rates at the dams significantly correlate to size of the contributing area. The average erosion rate normalized by drainage area was 0.001 foot per year below roads, 0.003 foot per year on hillslopes, and 0.011 foot per year below well pads. Results of a two-sample t-test indicate that there was no significant difference in average erosion rates for dams located on hillslopes and below roads, whereas average erosion rates were significantly greater for dams below well pads than for dams on

Modeling soil erosion and transport on forest landscape

Science.gov (United States)

Ge Sun; Steven G McNulty

1998-01-01

Century-long studies on the impacts of forest management in North America suggest sediment can cause major reduction on stream water quality. Soil erosion patterns in forest watersheds are patchy and heterogeneous. Therefore, patterns of soil erosion are difficult to model and predict. The objective of this study is to develop a user friendly management tool for land...

Land Capability Evaluation of Upper Sekampung Watersheds

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Irwan Sukri Banuwa

2008-05-01

Full Text Available Land degradation is a serious problem in the Upper Sekampung Watersheds. This is because the farmers cultivated in steep land to coffee crops without in adequate soil and water conservation practices. The land degradation is mostly caused by erosion. The erosion problem not only stripping the most fertile top soil and decreasing crop production, but also resulting problems in lowland. Therefore, the reorientation land management should be improved to produce agriculture sustainability. The first step is to evaluated land capability this area. The objectives of the research were evaluate land capability of Upper Sekampung Watersheds. The results showed that the Upper Sekampung Watersheds were dominated with class and subclass land capability of III-l2 about 17.630,51 ha (41,58%. All of the constrain for each land capability in this area is erosion hazard, especially land slope. From this research, cultivated land to coffee base crops were allowed in land capability II-l1.e1, III-l2, IV-l3, and VI-l4, with in adequate soil and water conservation practices. In contrary, the land capability of VII-l5 unsuitable for agriculture, they should be a nature or for conservation forest.

Estimation of Annual Average Soil Loss, Based on Rusle Model in Kallar Watershed, Bhavani Basin, Tamil Nadu, India

Science.gov (United States)

Rahaman, S. Abdul; Aruchamy, S.; Jegankumar, R.; Ajeez, S. Abdul

2015-10-01

Soil erosion is a widespread environmental challenge faced in Kallar watershed nowadays. Erosion is defined as the movement of soil by water and wind, and it occurs in Kallar watershed under a wide range of land uses. Erosion by water can be dramatic during storm events, resulting in wash-outs and gullies. It can also be insidious, occurring as sheet and rill erosion during heavy rains. Most of the soil lost by water erosion is by the processes of sheet and rill erosion. Land degradation and subsequent soil erosion and sedimentation play a significant role in impairing water resources within sub watersheds, watersheds and basins. Using conventional methods to assess soil erosion risk is expensive and time consuming. A comprehensive methodology that integrates Remote sensing and Geographic Information Systems (GIS), coupled with the use of an empirical model (Revised Universal Soil Loss Equation- RUSLE) to assess risk, can identify and assess soil erosion potential and estimate the value of soil loss. GIS data layers including, rainfall erosivity (R), soil erodability (K), slope length and steepness (LS), cover management (C) and conservation practice (P) factors were computed to determine their effects on average annual soil loss in the study area. The final map of annual soil erosion shows a maximum soil loss of 398.58 t/ h-1/ y-1. Based on the result soil erosion was classified in to soil erosion severity map with five classes, very low, low, moderate, high and critical respectively. Further RUSLE factors has been broken into two categories, soil erosion susceptibility (A=RKLS), and soil erosion hazard (A=RKLSCP) have been computed. It is understood that functions of C and P are factors that can be controlled and thus can greatly reduce soil loss through management and conservational measures.

Airphoto analysis of erosion control practices

Science.gov (United States)

Morgan, K. M.; Morris-Jones, D. R.; Lee, G. B.; Kiefer, R. W.

1980-01-01

The Universal Soil Loss Equation (USLE) is a widely accepted tool for erosion prediction and conservation planning. In this study, airphoto analysis of color and color infrared 70 mm photography at a scale of 1:60,000 was used to determine the erosion control practice factor in the USLE. Information about contour tillage, contour strip cropping, and grass waterways was obtained from aerial photography for Pheasant Branch Creek watershed in Dane County, Wisconsin.

Participatory policy development for integrated watershed management in Uganda's highlands

NARCIS (Netherlands)

Mutekanga, F.P.

2012-01-01

Soil erosion is a serious problem in the densely populated Uganda highlands and previous interventions were ineffective. This study, on the Ngenge watershed, Mount Elgon, was aimed at developing policy for the implementation of a new strategy for solving the problem, Integrated Watershed

Soil erosion fragility assessment using an impact model and geographic information system

OpenAIRE

Jorge,Luiz Alberto Blanco

2009-01-01

A study was taken in a 1566 ha watershed situated in the Capivara River basin, municipality of Botucatu, São Paulo State, Brazil. This environment is fragile and can be subjected to different forms of negative impacts, among them soil erosion by water. The main objective of the research was to develop a methodology for the assessment of soil erosion fragility at the various different watershed positions, using the geographic information system ILWIS version 3.3 for Windows. An impact model wa...

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

The Application of a WEPP Technology to a Complex Watershed Analysis

Science.gov (United States)

Elliot, William; Miller, Ina Sue; Dobre, Mariana

2017-04-01

Forest restoration activities are essential in many forest stands, where previous management and fire suppression has resulted in stands with high density, diseased trees and excessive fuel loads. Trying to balance the watershed impacts of restoration activities such as thinning, selective harvesting, and prescribed fire against the significant impact of wildfire is challenging. The process is further aggravated by the necessity of a road network if management activities include timber removal. We propose to present an approach to a watershed analysis for a 3400-ha of fuel reduction project within an 18,0000-ha sensitive watershed in the Nez Perce National Forest in Northern Idaho, USA. The FlamMap fire spread model was first used to predict the distribution of potential fire severity on the landscape for the current fuel load, and for a landscape that had been treated by thinning and/or prescribed fire. FlamMap predicts the flame length by 30-m pixel as a function of fuel load and water content, wind speed, and slope steepness and aspect. The flame length distribution was then classified so that the distribution of burn severity (unburned, low, moderate and high severity) was similar to the distributions observed on recent wildfires in the Forest. The flame length classes determined for the current fuel loads were also used for the treated condition flame lengths, where predominantly unburned or low severity fire severities were predicted. The burn severity maps were uploaded to a web site that was developed to provide soil and management files reflecting burn severity and soil texture, formatted for the Geospatial interface to the Water Erosion Prediction Project (GeoWEPP). The study area was divided into 40 sub watersheds under 2.5 km2 each for GeoWEPP analysis. GeoWEPP was run for an undisturbed forest; for the burn severity following wildfire for the current and treated fuel loads; for prescribed fire, either broadcast or jack pot burn; and for thinning either

Hydrology and soil erosion

Science.gov (United States)

Leonard J. Lane; Mary R. Kidwell

2003-01-01

We review research on surface water hydrology and soil erosion at the Santa Rita Experimental Range (SRER). Almost all of the research was associated with eight small experimental watersheds established from 1974 to 1975 and operated until the present. Analysis of climatic features of the SRER supports extending research findings from the SRER to broad areas of the...

Spatial Decision Assistance of Watershed Sedimentation (SDAS: Development and Application

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Poerbandono

2014-04-01

Full Text Available This paper discusses the development and application of a spatial tool for erosion modeling named Spatial Decision Assistance of Watershed Sedimentation (SDAS. SDAS computes export (yield of sediment from watershed as product of erosion rate and sediment delivery ratio (SDR. The erosion rate is calculated for each raster grid according to a digital elevation model, soil, rain fall depth, and land cover data using the Universal Soil Loss Equation. SDR calculation is carried out for each spatial unit. A spatial unit is the smallest sub-watershed considered in the model and generated according to the TauDEM algorithm. The size of one spatial unit is assigned by the user as the minimum number of raster grids. SDR is inversely proportional to sediment resident time and controlled by rainfall, slope, soil, and land cover. Application of SDAS is demonstrated in this paper by simulating the spatial distribution of the annual sediment yield across the Citarum watershed in the northwest of Java, Indonesia. SDAS calibration was carried out based on sediment discharge observations from the upper catchment. We considered factors for hillslope flow depth and for actual and effective rainfall duration to fit the computed sediment yield to the observed sediment discharge. The computed sediment yield agreed with the observation data with a 7% mean relative accuracy.

3D Agro-ecological Land Use Planning Using Surfer Tool for Sustainable Land Management in Sumani Watershed, West Sumatra Indonesia

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Aflizar

2013-09-01

Full Text Available Estimation of soil erosion 3D (E3D provides basic information that can help manage agricultural areas sustainably, which has not been sufficiently conducted in Indonesia. Sumani watershed is main rice production area in West Sumatra which has experienced environmental problem such as soil erosion and production problem in recent years. 3D Agro-ecological land use planning based on soil erosion 3D hazard and economic feasibility analyses consist of production cost and prize data for each crop. Using a kriging method in Surfer tool program, have been developed data base from topographic map, Landsat TM image, climatic data and soil psychochemical properties. Using these data, the Universal Soil Loss Equation was used for spatial map of soil erosion 3D and proposed a 3D agro-ecological land use planning for sustainable land management in Sumani watershed. A 3D Agro-ecological land use planning was planned under which the land use type would not cause more than tolerable soil erosion (TER and would be economically feasible. The study revealed that the annual average soil erosion from Sumani watershed was approximately 76.70 Mg ha-1yr-1 in 2011 where more than 100 Mg ha-1yr-1 was found on the cultivated sloping lands at agricultural field, which constitutes large portion of soil erosion in the watershed. Modification of land use with high CP values to one with lower CP values such as erosion control practices by reforestation, combination of mixed garden+beef+chicken (MBC, terrace (TBC or contour cropping+beef+chicken (CBC and sawah+buffalo+chicken (SBC could reduce soil erosion rate by 83.2%, from 76.70 to 12.9 Mg ha-1 yr-1, with an increase in total profit from agricultural production of about 9.2% in whole Sumani watershed.

Hydrosedimentological modeling of watershed in southeast Brazil, using SWAT

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Maria Lúcia Calijuri

2010-08-01

Full Text Available The quantitative evaluation of soil loss due to erosion, of water loss and of load sediments that reach water bodies is fundamental to the environmental planning of a watershed, contributing to the process of decision for best options for soil tillage and water quality maintenance. Estimates of these data have been accomplished throughout the world using empiric or conceptual models. Besides being economically viable in scenarios development, environmental models may contribute to the location of critical areas, leading to emergency contention operations caused by erosive processes. Among these models, we highlight the SWAT (Soil and Water Assessment Tool which was applied in São Bartolomeu watershed, located in the Zona da Mata, Minas Gerais state, southeastern Brazil, to identify areas of greater sensitivity to erosion considering the soil type and land use. To validate the model, 10 experimental plots were installed in the dominant crops of the watershed between 2006 and 2008, for monitoring the runoff and soil losses under natural rainfall. Field results and simulations showed the SWAT efficiency for sediment yield and soil losses estimations, as they are influenced by factors such as soil moisture, rainfall intensity, soil type and land use (dominated by Oxisols, Ultisols, Inceptisols and Entisols. These losses can be reduced significantly by improving crops management of. A simulation scenario replacing pastures cover by Eucalyptus was introduced, which significantly reduced soil loss in many parts of the watershed.

Grays River Watershed Geomorphic Analysis

Energy Technology Data Exchange (ETDEWEB)

Geist, David R

2005-04-30

This investigation, completed for the Pacific Northwest National Laboratory (PNNL), is part of the Grays River Watershed and Biological Assessment commissioned by Bonneville Power Administration under project number 2003-013-00 to assess impacts on salmon habitat in the upper Grays River watershed and present recommendations for habitat improvement. This report presents the findings of the geomorphic assessment and is intended to support the overall PNNL project by evaluating the following: The effects of historical and current land use practices on erosion and sedimentation within the channel network The ways in which these effects have influenced the sediment budget of the upper watershed The resulting responses in the main stem Grays River upstream of State Highway 4 The past and future implications for salmon habitat.

Geospatial application of the Water Erosion Prediction Project (WEPP) Model

Science.gov (United States)

D. C. Flanagan; J. R. Frankenberger; T. A. Cochrane; C. S. Renschler; W. J. Elliot

2011-01-01

The Water Erosion Prediction Project (WEPP) model is a process-based technology for prediction of soil erosion by water at hillslope profile, field, and small watershed scales. In particular, WEPP utilizes observed or generated daily climate inputs to drive the surface hydrology processes (infiltration, runoff, ET) component, which subsequently impacts the rest of the...

Simulating climate change impact on soil erosion using RUSLE model

Indian Academy of Sciences (India)

Climate change, particularly due to the changed precipitation trend, can have a severe impact on soil erosion. The effect is more pronounced on the higher slopes of the Himalayan region. The goal of this study was to estimate the impact of climate change on soil erosion in a watershed of the Himalayan region using ...

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

Delineation of potential deep seated landslides in a watershed using environmental index

Science.gov (United States)

Lai, Siao Ying; Lin, Chao Yuan; Lin, Cheng Yu

2016-04-01

The extreme rainfall induced deep seated landslides cause more attentions recently. Extreme rainfall can accelerate soil moisture content and surface runoff in slopeland which usually results in severe headward erosion and slope failures in an upstream watershed. It's a crucial issue for disaster prevention to extract the sites of potential deep seated landslide dynamically. Landslide risk and scale in a watershed were well discussed in this study. Risk of landslide occurrence in a watershed can be calculated from the multiplication of hazard and vulnerability for a certain event. A synthesis indicator derived from the indices of inverted extreme rainfall, road development and inverted normalized difference vegetation index can be effectively used as vulnerability for a watershed before the event. Landslide scale estimated from the indices of soil depth, headward erosion, river concave and dip slope could be applied to locate the hotspots of deep seated landslide in a watershed. The events of Typhoon Morakot in 2009 and Soudelor in 2015 were also selected in this study to verify the delineation accuracy of the model for the references of related authorities.

Binational digital soils map of the Ambos Nogales watershed, southern Arizona and northern Sonora, Mexico

Science.gov (United States)

Norman, Laura

2004-01-01

We have prepared a digital map of soil parameters for the international Ambos Nogales watershed to use as input for selected soils-erosion models. The Ambos Nogales watershed in southern Arizona and northern Sonora, Mexico, contains the Nogales wash, a tributary of the Upper Santa Cruz River. The watershed covers an area of 235 km2, just under half of which is in Mexico. Preliminary investigations of potential erosion revealed a discrepancy in soils data and mapping across the United States-Mexican border due to issues including different mapping resolutions, incompatible formatting, and varying nomenclature and classification systems. To prepare a digital soils map appropriate for input to a soils-erosion model, the historical analog soils maps for Nogales, Ariz., were scanned and merged with the larger-scale digital soils data available for Nogales, Sonora, Mexico using a geographic information system.

Mechanisms of acid reflux and how refluxed Acid extends proximally in patients with non-erosive reflux disease.

Science.gov (United States)

Sano, Hirohito; Iwakiri, Katsuhiko; Kawami, Noriyuki; Tanaka, Yuriko; Sakamoto, Choitsu

2014-01-01

The mechanisms that cause acid reflux in patients with non-erosive reflux disease (NERD), including those that determine how acid extends proximally, are not yet clear. Concurrent esophageal manometry and pH monitoring were performed for 3 h after a meal in 13 patients with NERD, 12 with mild reflux esophagitis (RE), and 13 healthy subjects (HS). Transient lower esophageal sphincter (LES) relaxation (TLESR) was the major mechanism of acid reflux in all three groups. LES pressure did not differ between the groups. At 2 cm above the LES, there were no differences between the three groups in the number of TLESR-related acid reflux episodes, rate of TLESRs and rate of acid reflux during TLESR. However, at 7 cm above the LES, the rate of acid reflux during TLESRs was significantly higher in patients with NERD (mean ± SEM 42.3 ± 4.8) than in those with mild RE (28.0 ± 3.8) and HS (10.8 ± 2.5). TLESRs are the sole motor events underlying acid reflux episodes in patients with NERD. Acid extends proximally more readily in patients with NERD than in HS and those with mild RE.

Asynchronous changes in vegetation, runoff and erosion in the nile river watershed during the holocene.

Science.gov (United States)

Blanchet, Cécile L; Frank, Martin; Schouten, Stefan

2014-01-01

The termination of the African Humid Period in northeastern Africa during the early Holocene was marked by the southward migration of the rain belt and the disappearance of the Green Sahara. This interval of drastic environmental changes was also marked by the initiation of food production by North African hunter-gatherer populations and thus provides critical information on human-environment relationships. However, existing records of regional climatic and environmental changes exhibit large differences in timing and modes of the wet/dry transition at the end of the African Humid Period. Here we present independent records of changes in river runoff, vegetation and erosion in the Nile River watershed during the Holocene obtained from a unique sedimentary sequence on the Nile River fan using organic and inorganic proxy data. This high-resolution reconstruction allows to examine the phase relationship between the changes of these three parameters and provides a detailed picture of the environmental conditions during the Paleolithic/Neolithic transition. The data show that river runoff decreased gradually during the wet/arid transition at the end of the AHP whereas rapid shifts of vegetation and erosion occurred earlier between 8.7 and ∼6 ka BP. These asynchronous changes are compared to other regional records and provide new insights into the threshold responses of the environment to climatic changes. Our record demonstrates that the degradation of the environment in northeastern Africa was more abrupt and occurred earlier than previously thought and may have accelerated the process of domestication in order to secure sustainable food resources for the Neolithic African populations.

Improvements in Quantifying Bank Erosion for Sediment Budgets within the Chesapeake Bay Watershed by Integrating Structure-From-Motion Photogrammetry

Science.gov (United States)

Bell, J. M.; Cashman, M. J.; Nibert, L.; Jackson, S.

2017-12-01

Fine sediment is a major source of pollution due to its ability to attenuate light, smother habitat, and sorb and transport nutrients, such as phosphorus and nitrogen. Piedmont streams in the Mid-Atlantic region of the United States are frequently characterized as incised with steep, highly erodible banks of legacy sediment that can contribute to high sediment loads. Multiple sediment fingerprinting studies in this region have demonstrated that stream banks can contribute a large proportion of the total sediment load, but stream banks are frequently overlooked in sediment delivery models and Total Maximum Daily Load allocations. The direct quantification of bank erosion is therefore essential to producing accurate sediment budgets, which are needed to inform the targeted mitigation and remediation of degraded fluvial systems. This study contrasts the use of traditional bank pin measurements, structure-from-motion photogrammetric techniques, and aerial LIDAR at sites within Maryland, USA. Bank pin measurements, representing only single points in space, were found to be highly variable with subjective initial placement often missing nearby, large-scale bank failures. In contrast, photogrammetric techniques, using structure-from-motion, were able to capture a more spatially-complete streambank profile. Using a Nikon D810 camera, bank scans were able to reconstruct banks with a RMSE as low as 0.1mm and repeat scan alignment resolution of bank-erosion over multi-year timescales. Future work will include difference mapping channel features at watershed scales. This photogrammetric approach of quantifying geomorphic change, when coupled with bank-sediment bulk density, has promise to accurately quantify volumetric change as well as sediment loads originating from bank erosion, and may provide valuable data of the quantification of bank erosion for incorporation into regional sediment models.

Predicting soil erosion using Rusle and NDVI time series from TM Landsat 5

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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.

Adapting the Water Erosion Prediction Project (WEPP) model for forest applications

Science.gov (United States)

Shuhui Dun; Joan Q. Wu; William J. Elliot; Peter R. Robichaud; Dennis C. Flanagan; James R. Frankenberger; Robert E. Brown; Arthur C. Xu

2009-01-01

There has been an increasing public concern over forest stream pollution by excessive sedimentation due to natural or human disturbances. Adequate erosion simulation tools are needed for sound management of forest resources. The Water Erosion Prediction Project (WEPP) watershed model has proved useful in forest applications where Hortonian flow is the major form of...

A method for modeling the effects of climate and land use changes on erosion and sustainability of soil in a Mediterranean watershed (Languedoc, France).

Science.gov (United States)

Paroissien, Jean-Baptiste; Darboux, Frédéric; Couturier, Alain; Devillers, Benoît; Mouillot, Florent; Raclot, Damien; Le Bissonnais, Yves

2015-03-01

Global climate and land use changes could strongly affect soil erosion and the capability of soils to sustain agriculture and in turn impact regional or global food security. The objective of our study was to develop a method to assess soil sustainability to erosion under changes in land use and climate. The method was applied in a typical mixed Mediterranean landscape in a wine-growing watershed (75 km(2)) within the Languedoc region (La Peyne, France) for two periods: a first period with the current climate and land use and a second period with the climate and land use scenarios at the end of the twenty-first century. The Intergovernmental Panel on Climate Change A1B future rainfall scenarios from the Météo France General circulation model was coupled with four contrasting land use change scenarios that were designed using a spatially-explicit land use change model. Mean annual erosion rate was estimated with an expert-based soil erosion model. Soil life expectancy was assessed using soil depth. Soil erosion rate and soil life expectancy were combined into a sustainability index. The median simulated soil erosion rate for the current period was 3.5 t/ha/year and the soil life expectancy was 273 years, showing a low sustainability of soils. For the future period with the same land use distribution, the median simulated soil erosion rate was 4.2 t/ha/year and the soil life expectancy was 249 years. The results show that soil erosion rate and soil life expectancy are more sensitive to changes in land use than to changes in precipitation. Among the scenarios tested, institution of a mandatory grass cover in vineyards seems to be an efficient means of significantly improving soil sustainability, both in terms of decreased soil erosion rates and increased soil life expectancies. Copyright © 2014 Elsevier Ltd. All rights reserved.

Lessons From Watershed-Based Climate Smart Agricultural Practices In Jogo-Gudedo Watershed Ethiopia

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Abera Assefa

2015-08-01

Full Text Available Abstract Land degradation is the most chronic problem in the Ethiopia. Soil erosion and denudation of vegetation covers are tending to enlarge the area of degraded and west land in semi-arid watersheds. It is therefore watershed management is believed as a holistic approach to create a climate smart landscape that integrate forestry agriculture pasture and soil water management with an objective of sustainable management of natural resources to improve livelihood. This approach pursues to promote interactions among multiple stakeholders and their interests within and between the upstream and downstream locations of a watershed. Melkassa Agricultural Research Centre MARC has been implementing integrated watershed management research project in the Jogo-gudedo watershed from 2010-2014 and lessons from Jogo-gudedo watershed are presented in this research report. Participatory action research PAR was implemented on Soil and Water Conservation SWC area enclosure Agroforestry AF Conservation Tillage CT energy saving stove drought resistance crop varieties in the Jogo-gudedo watershed. Empirical research and action research at plot level and evaluation of introduced technologies with farmers through experimental learning approach and documentation were employed. The participatory evaluation and collective action of SWC and improved practices brought high degree of acceptance of the practices and technologies. This had been ratified by the implementation of comprehensive watershed management action research which in turn enabled to taste and exploit benefits of climate-smart agricultural practices. Eventually significant reduction on soil loss and fuel wood consumption improvements on vegetation cover and crop production were quantitatively recorded as a good indicator and success. Field visit meetings trainings and frequent dialogues between practitioners and communities at watershed level have had a help in promoting the climate smart agriculture

Spatial and temporal dynamics of sediment in contrasted mountainous watersheds (Mexican transvolcanic belt and French Southern Alps) combining river gauging, elemental geochemistry and fallout radionuclides

Science.gov (United States)

Evrard, O.; Navratil, O.; Gratiot, N.; Némery, J.; Duvert, C.; Ayrault, S.; Lefèvre, I.; Legout, C.; Bonté, P.; Esteves, M.

2009-12-01

In mountainous environments, an excessive fine sediment supply to the rivers typically leads to an increase in water turbidity, contaminant transport and a rapid filling of reservoirs. This situation is particularly problematic in regions where water reservoirs are used to provide drinking water to large cities (e.g. in central Mexico) or where stream water is used to run hydroelectric power plants (e.g. in the French Southern Alps). In such areas, sediment source areas first need to be delineated and sediment fluxes between hillslopes and the river system must be better understood before implementing efficient erosion control measures. In this context, the STREAMS (« Sediment Transport and Erosion Across MountainS ») project funded by the French National Research Agency (ANR) aims at understanding the spatial and temporal dynamics of sediment at the scale of mountainous watersheds (between 500 - 1000 km2) located in contrasted environments. This 3-years study is carried out simultaneously in a volcanic watershed located in the Mexican transvolcanic belt undergoing a subhumid tropical climate, as well as in a sedimentary watershed of the French Southern Alps undergoing a transitional climate with Mediterranean and continental influences. One of the main specificities of this project consists in combining traditional monitoring techniques (i.e. installation of river gauges, turbidimeters and sediment samplers in several sub-catchments) and sediment fingerprinting using elemental geochemistry (measured by Instrumental Neutron Activation Analysis - INAA - and Inductively Coupled Plasma - Mass Spectrometry - ICP-MS) and fallout radionuclides (measured by gamma spectrometry). In the French watershed, geochemical analysis allows outlining different sediment sources (e.g. the contribution of calcareous vs. marl-covered sub-watersheds). Radionuclide ratios (e.g.Be-7/Cs-137) allow identifying the dominant erosion processes occurring within the watershed. Areas mostly

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

Assessment of Runoff and Sediment Yields Using the AnnAGNPS Model in a Three-Gorge Watershed of China

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Hongwei Nan

2012-05-01

Full Text Available Soil erosion has been recognized as one of the major threats to our environment and water quality worldwide, especially in China. To mitigate nonpoint source water quality problems caused by soil erosion, best management practices (BMPs and/or conservation programs have been adopted. Watershed models, such as the Annualized Agricultural Non-Point Source Pollutant Loading model (AnnAGNPS, have been developed to aid in the evaluation of watershed response to watershed management practices. The model has been applied worldwide and proven to be a very effective tool in identifying the critical areas which had serious erosion, and in aiding in decision-making processes for adopting BMPs and/or conservation programs so that cost/benefit can be maximized and non-point source pollution control can be achieved in the most efficient way. The main goal of this study was to assess the characteristics of soil erosion, sediment and sediment delivery of a watershed so that effective conservation measures can be implemented. To achieve the overall objective of this study, all necessary data for the 4,184 km² Daning River watershed in the Three-Gorge region of the Yangtze River of China were assembled. The model was calibrated using observed monthly runoff from 1998 to 1999 (Nash-Sutcliffe coefficient of efficiency of 0.94 and R² of 0.94 and validated using the observed monthly runoff from 2003 to 2005 (Nash-Sutcliffe coefficient of efficiency of 0.93 and R² of 0.93. Additionally, the model was validated using annual average sediment of 2000–2002 (relative error of −0.34 and 2003–2004 (relative error of 0.18 at Wuxi station. Post validation simulation showed that approximately 48% of the watershed was under the soil loss tolerance released by the Ministry of Water Resources of China (500 t·km⁻²·y⁻¹. However, 8% of the watershed had soil erosion of exceeding 5,000 t·km⁻²

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

Watershed Evaluation and Habitat Response to Recent Storms : Annual Report for 1998.

Energy Technology Data Exchange (ETDEWEB)

Rhodes, Jonathan J.; Huntington, Charles W.

1999-01-01

Large and powerful storm systems moved through the Pacific Northwest during the wet season of 1995-96, triggering widespread flooding, mass erosion, and, possibly altering salmon habitats in affected watersheds. This project study was initiated to assess whether watershed conditions are causing damage, triggered by storm events, to salmon habitat on public lands in the Snake River basin.

Estimation Model of Soil Freeze-Thaw Erosion in Silingco Watershed Wetland of Northern Tibet

OpenAIRE

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 S...

Spatial Resolution Effect on Forest Road Gradient Calculation and Erosion Modelling

Science.gov (United States)

Cao, L.; Elliot, W.

2017-12-01

Road erosion is one of the main sediment sources in a forest watershed and should be properly evaluated. With the help of GIS technology, road topography can be determined and soil loss can be predicted at a watershed scale. As a vector geographical feature, the road gradient should be calculated following road direction rather than hillslope direction. This calculation might be difficult with a coarse (30-m) DEM which only provides the underlying topography information. This study was designed to explore the effect of road segmentation and DEM resolution on the road gradient calculation and erosion prediction at a watershed scale. The Water Erosion Prediction Project (WEPP) model was run on road segments of 9 lengths ranging from 40m to 200m. Road gradient was calculated from three DEM data sets: 1m LiDAR, and 10m and 30m USGS DEMs. The 1m LiDAR DEM calculated gradients were very close to the field observed road gradients, so we assumed the 1m LiDAR DEM predicted the true road gradient. The results revealed that longer road segments skipped detail topographical undulations and resulted in lower road gradients. Coarser DEMs computed steeper road gradients as larger grid cells covered more adjacent areas outside road resulting in larger elevation differences. Field surveyed results also revealed that coarser DEM might result in more gradient deviation in a curved road segment when it passes through a convex or concave slope. As road segment length increased, the gradient difference between three DEMs was reduced. There were no significant differences between road gradients of different segment lengths and DEM resolution when segments were longer than 100m. For long segments, the 10m DEM calculated road gradient was similar to the 1m LiDAR gradient. When evaluating the effects of road segment length, the predicted erosion rate decreased with increasing length when road gradient was less than 3%. In cases where the road gradients exceed 3% and rill erosion dominates

Optimal land use/cover classification using remote sensing imagery for hydrological modelling in a Himalayan watershed

NARCIS (Netherlands)

Sameer Saran,; Sterk, G.; Kumar, S.

2007-01-01

Land use/cover is an important watershed surface characteristic that affects surface runoff and erosion. Many of the available hydrological models divide the watershed into Hydrological Response Units (HRU), which are spatial units with expected similar hydrological behaviours. The division into

Long-term background denudation rates of southern and southeastern Brazilian watersheds estimated with cosmogenic 10Be

Science.gov (United States)

Sosa Gonzalez, Veronica; Bierman, Paul R.; Fernandes, Nelson F.; Rood, Dylan H.

2016-09-01

In comparison to humid temperate regions of the Northern Hemisphere, less is known about the long-term (millennial scale) background rates of erosion in Southern Hemisphere tropical watersheds. In order to better understand the rate at which watersheds in southern and southeastern Brazil erode, and the relationship of that erosion to climate and landscape characteristics, we made new measurements of in situ produced 10Be in river sediments and we compiled all extant measurements from this part of the country. New data from 14 watersheds in the states of Santa Catarina (n = 7) and Rio de Janeiro (n = 7) show that erosion rates vary there from 13 to 90 m/My (mean = 32 m/My; median = 23 m/My) and that the difference between erosion rates of basins we sampled in the two states is not significant. Sampled basin area ranges between 3 and 14,987 km2, mean basin elevation between 235 and 1606 m, and mean basin slope between 11 and 29°. Basins sampled in Rio de Janeiro, including three that drain the Serra do Mar escarpment, have an average basin slope of 19°, whereas the average slope for the Santa Catarina basins is 14°. Mean basin slope (R2 = 0.73) and annual precipitation (R2 = 0.57) are most strongly correlated with erosion in the basins we studied. At three sites where we sampled river sand and cobbles, the 10Be concentration in river sand was greater than in the cobbles, suggesting that these grain sizes are sourced from different parts of the landscape. Compiling all cosmogenic 10Be-derived erosion rates previously published for southern and southeastern Brazil watersheds to date (n = 76) with our 14 sampled basins, we find that regional erosion rates (though low) are higher than those of watersheds also located on other passive margins including Namibia and the southeastern North America. Brazilian basins erode at a pace similar to escarpments in southeastern North America. Erosion rates in southern and southeastern Brazil are directly and positively related to

Soil loss estimation using geographic information system in enfraz watershed for soil conservation planning in highlands of Ethiopia

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Gizachew Tiruneh

2015-12-01

Full Text Available Accelerated soil erosion is a worldwide problem because of its economic and environmental impacts. Enfraz watershed is one of the most erosion-prone watersheds in the highlands of Ethiopia, which received little attention. This study was, therefore, carried out to spatially predict the soil loss rate of the watershed with a Geographic Information System (GIS and Remote Sensing (RS. Revised Universal Soil Loss Equation (RUSLE adapted to Ethiopian conditions was used to estimate potential soil losses by utilizing information on rainfall erosivity (R using interpolation of rainfall data, soil erodibility (K using soil map, vegetation cover (C using satellite images, topography (LS using Digital Elevation Model (DEM and conservation practices (P using satellite images. Based on the analysis, about 92.31% (5914.34 ha of the watershed was categorized none to slight class which under soil loss tolerance (SLT values ranging from 5 to 11 tons ha-1 year-1. The remaining 7.68% (492.21 ha of land was classified under moderate to high class about several times the maximum tolerable soil loss. The total and an average amount of soil loss estimated by RUSLE from the watershed was 30,836.41 ton year-1 and 4.81 tons ha-1year-1, respectively.

Climate Change Impacts on Sediment Transport In a Lowland Watershed System: Controlling Processes and Projection

Science.gov (United States)

al Aamery, N. M. H.; Mahoney, D. T.; Fox, J.

2017-12-01

Future climate change projections suggest extreme impacts on watershed hydrologic systems for some regions of the world including pronounced increases in surface runoff and instream flows. Yet, there remains a lack of research focused on how future changes in hydrologic extremes, as well as relative hydrologic mean changes, impact sediment redistribution within a watershed and sediment flux from a watershed. The authors hypothesized that variations in mean and extreme changes in turn may impact sediments in depositional and erosional dominance in a manner that may not be obvious to the watershed manager. Therefore, the objectives of this study were to investigate the inner processes connecting the combined effect of extreme climate change projections on the vegetation, upland erosion, and instream processes to produce changes in sediment redistribution within watersheds. To do so, research methods were carried out by the authors including simulating sediment processes in forecast and hindcast periods for a lowland watershed system. Publically available climate realizations from several climate factors and the Soil Water Assessment Tool (SWAT) were used to predict hydrologic conditions for the South Elkhorn Watershed in central Kentucky, USA to 2050. The results of the simulated extreme and mean hydrological components were used in simulating upland erosion with the connectivity processes consideration and thereafter used in building and simulating the instream erosion and deposition of sediment processes with the consideration of surface fine grain lamina (SFGL) layer controlling the benthic ecosystem. Results are used to suggest the dominance of erosional and depositional redistribution of sediments under different scenarios associated with extreme and mean hydrologic forecasting. The results are discussed in reference to the benthic ecology of the stream system providing insight on how water managers might consider sediment redistribution in a changing climate.

Effects of Fire on Soil Properties, Erosion and Hydrologic Regime of Zrebar Lake Watershed

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Shirko Ebrahimi Mohammadi

2017-02-01

Full Text Available Introduction: Forest herbs due to decrease of runoff coefficient and the kinetic energy of raindrops, is known as a key factor in controlling runoff and soil conservation. Many physical (hydrophobicity, electrical conductivity, pH, particle size distribution, color and temperature regimes, chemical (quality and quantity of organic matter, nutrient availability and biological (Microbial biomass, soil invertebrates living community soil properties can be affected by forest fires. Fire not only reduces forest herbs, vulnerability against splashing rain but also has strong effects on the hydrological cycle and soil loss. despite of repeated fires, there are very few studies about fire impact on natural resources of the west of the country, especially the city of Marivan, in Kurdistan province so this study aimed to investigate the short-term fire impacts on soil properties, Hydrologic regime, soil erosion and sedimentation of Zrebar Lake watershed in west of Iran. Materials and Methods: Considering the importance of the slope on the hydrological response of the watershed, slope classes of the Zrebar Lake watershed were mapped. Therefore, effects of fire on hydrological characteristics, erosion and sedimentation were studied by the establishment of twelve 0.25 square meter plots in three replications at two dominant slope classes (0 to 30 and 30 to 60% in burned and natural areas . The first plots in the burned and natural sections, was established randomly and two other plots with the similar conditions at a distance of 1.5 meters from each other were established. Garden Spray Simulator with constant pressure was used to fall rain from half a meter height for thirty minutes with an intensity of about 2 mm min-1 and 1 mm droplet diameter according to the general weather conditions of the studied area. For every five minutes, runoff and sediment were collected. Runoff volume by weighting and suspended sediment concentration by drying at 105°c were

Watershed evaluation and habitat response to recent storms : annual report for 1998; ANNUAL

International Nuclear Information System (INIS)

Huntington, Charles W.; Rhodes, Jonathan J.

1999-01-01

Large and powerful storm systems moved through the Pacific Northwest during the wet season of 1995-96, triggering widespread flooding, mass erosion, and, possibly altering salmon habitats in affected watersheds. This project study was initiated to assess whether watershed conditions are causing damage, triggered by storm events, to salmon habitat on public lands in the Snake River basin

Rainfall, soil moisture, and runoff dynamics in New Mexico pinon-juniper woodland watersheds

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Carlos Ochoa; Alexander Fernald; Vincent Tidwell

2008-01-01

Clearing trees in pinon-juniper woodlands may increase grass cover and infiltration, leading to reduced surface runoff and erosion. This study was conducted to evaluate pinon-juniper hydrology conditions during baseline data collection in a paired watershed study. We instrumented six 1.0 to 1.3 ha experimental watersheds near Santa Fe, NM to collect rainfall, soil...

Response of conservation measures from small cultivated watersheds, concerning runoff and erosion, under the impact of extreme rainfall events

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Popa, N.

2008-11-01

The study has been made in a representative small watershed with gently to hilly slopes from Tutova Rolling Hills, Romania. The system of conservation measures is represented by stripcroping, bufferstrips, bench terraces, a grassed waterway and a drainage network. The monitoring of hydrological response of agricultural units has been made in two cross sections corresponding to each of the land use type by means of two concrete triangular weirs. The most important soil losses were caused by three extreme rainfall events from August 2004, May 2005 and September 2007. At the date of the first rainfall event, the soil was generally very well protected against erosion by the vegetative cover, excepting parcels that were just ploughed after the mash crop. In that case, it was estimated that the value of soil losses ranged between 20.0 and 24.5 t/ha while for the other crops like corn and soybean, soil losses they were 1.0-1.5 t/ha and 0.5-0.8 t/ha respectively. Damages caused by the rainfall from September 2007 were much more important because at that time about 30% from the entire surface was just prepared for rape seeding. Maximum value of erosion was 95 t/ha on a parcel with 16% slope and 50m length along the slope.

Response of conservation measures from small cultivated watersheds, concerning runoff and erosion, under the impact of extreme rainfall events

International Nuclear Information System (INIS)

Popa, N

2008-01-01

The study has been made in a representative small watershed with gently to hilly slopes from Tutova Rolling Hills, Romania. The system of conservation measures is represented by stripcroping, bufferstrips, bench terraces, a grassed waterway and a drainage network. The monitoring of hydrological response of agricultural units has been made in two cross sections corresponding to each of the land use type by means of two concrete triangular weirs. The most important soil losses were caused by three extreme rainfall events from August 2004, May 2005 and September 2007. At the date of the first rainfall event, the soil was generally very well protected against erosion by the vegetative cover, excepting parcels that were just ploughed after the mash crop. In that case, it was estimated that the value of soil losses ranged between 20.0 and 24.5 t/ha while for the other crops like corn and soybean, soil losses they were 1.0-1.5 t/ha and 0.5-0.8 t/ha respectively. Damages caused by the rainfall from September 2007 were much more important because at that time about 30% from the entire surface was just prepared for rape seeding. Maximum value of erosion was 95 t/ha on a parcel with 16% slope and 50m length along the slope.

Hydrological Implication of Bamboo And Mixed Garden In The upper Citarum Watershed

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Chay Asdak

2013-07-01

Full Text Available The assessment of important factors affecting runoff and erosion was carried out by collecting runoff and soil loss from four runoff/erosion plots. The runoff/erosion plots were set up in sloping areas of about 40% slope in the upper area of Ciwidey sub-watershed (upper Citarum watershed, West Java. The plots (6 x 10 m were established in the following four sets of conditions: bamboo plantation, mixed garden, small shrub, and agricultural field with different species and stand structures. After 20 rainfall events, a treatment in the form of removing undergrowth and litter were applied to bamboo and mixed garden plots. The result of this before and after treatment are the following: runoff from bamboo plantation was increased from 0.40 to 1.02 litre/m2 and erosion was increased from 1.47 to 11.65 gr/m2. While the runoff and erosion in mixed garden were increased from 0.36 to 1.65 litre/m2 and from 1.36 to 10.88 65 gr/m2, respectively. When this compared to the runoff and soil loss in the agricultural plot, the soil erosion is much higher, 50.5 gr/m2 (about 50 times higher. Stand/canopy structure appeared to be the important factors that determine the magnitude of soil erosion. While the role of these factors were less significant compared to rainfall in determining the magnitude of runoff.

Erosion control and protection from torrential floods in Serbia-spatial aspects

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Ristić Ratko

2011-01-01

Full Text Available Torrential floods represent the most frequent phenomenon within the category of “natural risks” in Serbia. The representative examples are the torrential floods on the experimental watersheds of the rivers Manastirica (June 1996 and Kamišna (May 2007. Hystorical maximal discharges (Qmaxh were reconstructed by use of ″hydraulics flood traces″ method. Computations of maximal discharges (Qmaxc, under hydrological conditions after the restoration of the watersheds, were performed by use of a synthetic unit hydrograph theory and Soil Conservation Service methodology. Area sediment yields and intensity of erosion processes were estimated on the basis of the “Erosion Potential Method”. The actual state of erosion processes is represented by the coefficients of erosion Z=0.475 (Manastirica and Z=0.470 (Kamišna. Restoration works have been planned with a view to decreasing yields of erosive material, increasing water infiltration capacity and reducing flood runoff. The planned state of erosion processes is represented by the coefficients of erosion Z=0.343 (Manastirica and Z=0.385 (Kamišna. The effects of hydrological changes were estimated by the comparison of historical maximal discharges and computed maximal discharges (under the conditions after the planned restoration. The realisation of restoration works will help decrease annual yields of erosive material from Wа=24357 m3 to Wа=16198.0 m3 (Manastirica and from Wа=19974 m3 to Wа=14434 m3 (Kamišna. The values of historical maximal discharges (QmaxhMan=154.9 m3•s-1; QmaxhKam=76.3 m3•s-1 were significantly decreased after the restoration (QmaxcMan=84.5 m3 •s-1; QmaxcKam=43.7 m3•s-1, indicating the improvement of hydrological conditions, as a direct consequence of erosion and torrent control works. Integrated management involves biotechnical works on the watershed, technical works on the hydrographic network within a precisely defined administrative and spatial framework in

Use of cesium-137 methodology in the evaluation of superficial erosive processes

International Nuclear Information System (INIS)

Andrello, Avacir Casanova; Appoloni, Carlos Roberto; Guimaraes, Maria de Fatima; Nascimento Filho, Virgilio Franco do

2003-01-01

Superficial erosion is one of the main soil degradation agents and erosion rates estimations for different edaphic climate conditions for the conventional models, as USLE and RUSLE, are expensive and time-consuming. The use of cesium- 137 anthropogenic radionuclide is a new methodology that has been much studied and its application in the erosion soil evaluation has grown in countries as USA, UK, Australia and others. A brief narration of this methodology is being presented, as the development of the equations utilized for the erosion rates quantification through the cesium- 137 measurements. Two watersheds studied in Brazil have shown that the cesium- 137 methodology was practicable and coherent with the survey in field for applications in erosion studies. (author)

Fort Cobb Reservoir Watershed, Oklahoma and Thika River Watershed, Kenya Twinning Pilot Project

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Moriasi, D.; Steiner, J.; Arnold, J.; Allen, P.; Dunbar, J.; Shisanya, C.; Gathenya, J.; Nyaoro, J.; Sang, J.

2007-12-01

The Fort Cobb Reservoir Watershed (FCRW) (830 km2) is a watershed within the HELP Washita Basin, located in Caddo and Washita Counties, OK. It is also a benchmark watershed under USDA's Conservation Effects Assessment Project, a national project to quantify environmental effects of USDA and other conservation programs. Population in south-western Oklahoma, in which FCRW is located, is sparse and decreasing. Agricultural focuses on commodity production (beef, wheat, and row crops) with high costs and low margins. Surface and groundwater resources supply public, domestic, and irrigation water. Fort Cobb Reservoir and contributing stream segments are listed on the Oklahoma 303(d) list as not meeting water quality standards based on sedimentation, trophic level of the lake associated with phosphorus loads, and nitrogen in some stream segments in some seasons. Preliminary results from a rapid geomorphic assessment results indicated that unstable stream channels dominate the stream networks and make a significant but unknown contribution to suspended-sediment loadings. Impairment of the lake for municipal water supply, recreation, and fish and wildlife are important factors in local economies. The Thika River Watershed (TRW) (867 km2) is located in central Kenya. Population in TRW is high and increasing, which has led to a poor land-population ratio with population densities ranging from 250 people/km2 to over 500 people/km2. The poor land-population ratio has resulted in land sub-division, fragmentation, over- cultivation, overgrazing, and deforestation which have serious implications on soil erosion, which poses a threat to both agricultural production and downstream reservoirs. Agricultural focuses mainly on subsistence and some cash crops (dairy cattle, corn, beans, coffee, floriculture and pineapple) farming. Surface and groundwater resources supply domestic, public, and hydroelectric power generation water. Thika River supplies 80% of the water for the city of

Scenario Analysis of Soil and Water Conservation in Xiejia Watershed Based on Improved CSLE Model

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Liu, Jieying; Yu, Ming; Wu, Yong; Huang, Yao; Nie, Yawen

2018-01-01

According to the existing research results and related data, use the scenario analysis method, to evaluate the effects of different soil and water conservation measures on soil erosion in a small watershed. Based on the analysis of soil erosion scenarios and model simulation budgets in the study area, it is found that all scenarios simulated soil erosion rates are lower than the present situation of soil erosion in 2013. Soil and water conservation measures are more effective in reducing soil erosion than soil and water conservation biological measures and soil and water conservation tillage measures.

Soil erosion in Iran: Issues and solutions

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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

Determination of effective factors on the occurrence of digitated gully erosion in the AghEmam(2 watershed

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Maryam Mohammad Ebrahimi

2017-03-01

Full Text Available Introduction: Soil erosion by water is one of the most important processes of land degradation, especially in semi-arid areas. Among different types of the soil erosion, gully erosion accounts as one of the most critical processes which can cause soil destruction, changes in landscape and water resources filling of reservoir of dams,decrease in water transport capacity of rivers and agricultural lands destruction in the lowland areas. Based on the Posen definition, gully is a river with high slope walls and an erosive high slope and active head which occurs by erosion resulted from the surface flow (usually during or after high density rainfalls. Different factors play role in occurrence and development of gullies and sediment production resulted of this kind of erosion which includes slope, amount and distribution of rainfall intensity, construction operations, vegetable cover destruction, land-use change, unsuitable utilization, and susceptibility of bed materials to the erosion and flood. Considering the importance of gully erosion and the way of its occurrence and development and its control, more comprehensive studies are needed to be done. Although, some studies have done in this subject that some of them are depicted below: Rinkez et al showed that gully erosion is further occurred in soils with high exchangeable sodium percentage and sodium absorption ratio and they depicted that these two factors are important indices for soil diffusion amount in gullies. Buma and imson investigated factors such as electricity conductivity, calcium carbonate percentage, and the type of clay mineral in white, brown, and gray samples of marl in the Peter area, Spain. According to their results, factors such as electrical conductivity and sodium absorption ratio had high correlation with erosivity of the Bad Lands. Material and Methods: Agh Emam(2 watershed is located between 55º 42´ 53˝ to 55º 45´ 43˝ eastern longitudes and 37º 41´ 01˝ to 37º 46

Caesium fallout as a tracer of erosion-sedimentation

International Nuclear Information System (INIS)

Bouhlassa, S.; Azenfar, A.; Machrouh, A.

1994-01-01

The purpose of this paper is to set up a methodology of use of radioactive caesium fallout, to measure erosion and sedimentation in a sub-catchment and to establish the effects of geomorphological parameters, land uses and soil nature, on the losses caesium by physical process. The result obtained by this new and elegant approach, on a watershed of 4114 ha., studied before by classical and conventional techniques, gives a good evaluation of erosion, but also sedimentation rate, and permit to stand up, a model and sampling strategy, to extend the method to large catchment. 1 tab., 2 refs. (author)

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

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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

Soil loss estimation and prioritization of sub-watersheds of Kali River basin, Karnataka, India, using RUSLE and GIS.

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Markose, Vipin Joseph; Jayappa, K S

2016-04-01

Most of the mountainous regions in tropical humid climatic zone experience severe soil loss due to natural factors. In the absence of measured data, modeling techniques play a crucial role for quantitative estimation of soil loss in such regions. The objective of this research work is to estimate soil loss and prioritize the sub-watersheds of Kali River basin using Revised Universal Soil Loss Equation (RUSLE) model. Various thematic layers of RUSLE factors such as rainfall erosivity (R), soil erodibility (K), topographic factor (LS), crop management factor (C), and support practice factor (P) have been prepared by using multiple spatial and non-spatial data sets. These layers are integrated in geographic information system (GIS) environment and estimated the soil loss. The results show that ∼42 % of the study area falls under low erosion risk and only 6.97 % area suffer from very high erosion risk. Based on the rate of soil loss, 165 sub-watersheds have been prioritized into four categories-very high, high, moderate, and low erosion risk. Anthropogenic activities such as deforestation, construction of dams, and rapid urbanization are the main reasons for high rate of soil loss in the study area. The soil erosion rate and prioritization maps help in implementation of a proper watershed management plan for the river basin.

Weathering, landscape equilibrium, and carbon in four watersheds in eastern Puerto Rico: Chapter H in Water quality and landscape processes of four watersheds in eastern Puerto Rico

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Stallard, Robert F.; Murphy, Sheila F.; Stallard, Robert F.

2012-01-01

erosion in the two developed watersheds. Because there has been no appreciable deforestation, something else, possibly climate or forest-quality change, must explain the accelerated erosion in the forested watersheds on granitic rocks. Particulate organic carbon yields are closely linked to sediment yields. This relation implies that much of the particulate organic carbon transport in the four rivers is being caused by this enhanced erosion aided by landslides and fast carbon recovery. The increase in particulate organic carbon yields over equilibrium is estimated to range from 300 kilomoles per square kilometer per year (6 metric tons carbon per square kilometer per year) to 1,700 kilomoles per square kilometer per year (22 metric tons carbon per square kilometer per year) and is consistent with human-accelerated particulate-organic-carbon erosion and burial observed globally. There is no strong evidence of human perturbation of silicate weathering in the four study watersheds, and differences in dissolved inorganic carbon are consistent with watershed geology. Although dissolved organic carbon is slightly elevated in the developed watersheds, that elevation is not enough to unambiguously demonstrate human causes; more work is needed. Accordingly, the dissolved organic carbon and dissolved inorganic carbon yields of tropical rivers, although large, are of secondary importance in the study of the anthropgenically perturbed carbon cycle.

AUTOMATED GEOSPATIAL WATERSHED ASSESSMENT ...

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The Automated Geospatial Watershed Assessment tool (AGWA) is a GIS interface jointly developed by the USDA Agricultural Research Service, the U.S. Environmental Protection Agency, the University of Arizona, and the University of Wyoming to automate the parameterization and execution of the Soil Water Assessment Tool (SWAT) and KINEmatic Runoff and EROSion (KINEROS2) hydrologic models. The application of these two models allows AGWA to conduct hydrologic modeling and watershed assessments at multiple temporal and spatial scales. AGWA’s current outputs are runoff (volumes and peaks) and sediment yield, plus nitrogen and phosphorus with the SWAT model. AGWA uses commonly available GIS data layers to fully parameterize, execute, and visualize results from both models. Through an intuitive interface the user selects an outlet from which AGWA delineates and discretizes the watershed using a Digital Elevation Model (DEM) based on the individual model requirements. The watershed model elements are then intersected with soils and land cover data layers to derive the requisite model input parameters. The chosen model is then executed, and the results are imported back into AGWA for visualization. This allows managers to identify potential problem areas where additional monitoring can be undertaken or mitigation activities can be focused. AGWA also has tools to apply an array of best management practices. There are currently two versions of AGWA available; AGWA 1.5 for

Virgin Islands: Coral Bay Watershed Management (A Former EPA CARE Project)

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The Coral Bay Watershed Management is a recipient of the Level II CARE cooperative agreement to continue and expand its collective efforts to stop erosion, sediment, and storm-water pollution of Coral Bay, improve solid waste management,

Regional oesophageal sensitivity to acid and weakly acidic reflux in patients with non-erosive reflux disease.

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Emerenziani, S; Ribolsi, M; Sifrim, D; Blondeau, K; Cicala, M

2009-03-01

The mechanisms underlying symptoms in non-erosive reflux disease (NERD) remain to be elucidated. Non-erosive reflux disease patients appear to be more sensitive to intraluminal stimula than erosive patients, the proximal oesophagus being the most sensitive. In order to assess regional oesophageal changes in reflux acidity and sensitivity to reflux, according either to the acidity or the composition of the refluxate, combined multiple pH and multiple pH-impedance (pH-MII) was performed in 16 NERD patients. According to multiple pH-metry, 29% and 12% of reflux events reached the middle and proximal oesophagus respectively, and 35% and 19% according to conventional pH-MII (P acid reflux became weakly acidic at the proximal oesophagus. In all patients, the frequency of symptomatic refluxes, both acid and weakly acidic, was significantly higher at the proximal, compared with distal oesophagus (25 +/- 8%vs 11 +/- 2% for acid reflux and 27 +/- 8%vs 8 +/- 2% for weakly acidic reflux; P reflux. As approximately 30% of acid reflux becomes weakly acidic along the oesophageal body, to better characterize proximal reflux, in clinical practice, combined proximal pH-impedance monitoring should be used. In NERD patients, the proximal oesophagus seems to be more sensitive to both acid and weakly acidic reflux.

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 ...

Sediment budget for Murder Creek, Georgia, USA, from Pu239+240 - determined soil erosion rates

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Stubblefield, A. P.; Matissoff, G.; Ketterer, M. E.; Whiting, P. J.

2005-12-01

Soil inventories of the radionuclides Cs137 and Pb210 have been used in a variety of environments as indicators for erosion and depositional processes. Development of sediment budgets for entire watersheds from radionuclide data has been somewhat constrained because limited sample numbers may not adequately characterize the wide range of geomorphic conditions and land uses found in heterogeneous environments. The measurement of Pu239+240 shows great potential for developing quantitative watershed sediment budgets. With inductively-coupled plasma mass spectrometry, hundreds of samples may be processed in dramatically shorter times than the gamma spectrometry method used for Cs137 or alpha spectrometry method used for Pb210. We collected surface soil samples from Murder Creek in the Piedmont region of Georgia, USA, to compare Pu239+240 inventories with Cs137 and Pb210 inventories for a range of land uses in a predominantly forested watershed. Excellent correlations were found for radionuclide inventories (r2 =0.88, n = 38) and high resolution (4 mm) depth profiles. The second objective was to generate a sediment budget using the full Pu239+240 dataset (n = 309). Average Pu239+240 inventories were 70.0 Bq/m2 for hardwood forest, 60.0 Bq/m2 for pine plantation, 65.1 Bq/m2 for pine forest, 66.7 Bq/m2 for row crop agriculture and 67.9 Bq/m2 for pasture. The sediment budget will be constructed by converting inventories into site-specific erosion rates. Erosion rates will be scaled up to the watershed scale using GIS coverages of land use, soil, slope, and slope position. Results will be compared with Murder Creek sediment budgets in the scientific literature generated from RUSLE erosion modeling, USGS monitoring networks and reservoir sedimentation.

PENGKLASTERAN EROSI DI SUB DAS NGRANCAH KULONROGO (Soil Erosion Rates Clustering of Ngrancah Sub Watershed, Kulon Progo

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Ambar Kusumandari

2012-03-01

Full Text Available ABSTRAK Penelitian ini dilakukan di Sub DAS Ngrancah yang merupakan daerah tangkapan air Waduk Sermo. Luas wilayah penelitian ini sekitar 2.200 ha. Mayoritas lahan di Sub DAS Ngrancah tergolong kritis yang ditunjukkan oleh tingginya tingkat erosi. Dengan demikian, wilayah ini sangat mendesak untuk dapat dikelola dengan benar agar degradasi lahan dapat dihambat. Untuk memprediksi erosi, diterapkan Model USLE, dengan rumus: A = RKLSCP. Wilayah studi dapat dipilahkan menjadi 77 unit lahan. Sampel tanah diambil dari seluruh unit lahan, demikian pula pengamatan lereng, vegetasi, dan penerapan konservasi tanah. Untuk menganalisis data digunakan analisis kluster. Hasil penelitian menunjukkan bahwa tingkat erosi bervariasi dari yang paling rendah sebesar 2,54 ton/ha/th sampai dengan yang tertinggi sebesar 489,30 ton/ha/th. Sekitar 68% wilayah studi termasuk dalam kelas erosi sedang dan sekitar 15% wilayah studi termasuk dalam kelas erosi tinggi. Pengklasteran unit lahan secara statistik menunjukkan bahwa pada jarak klaster terpendek terbentuk 8 klaster tingkat erosi. Uji diskriminan menunjukkan bahwa faktor K (erodibilitas dan P (praktek konservasi tanah dan air merupakan faktor yang paling dominan untuk terbentuknya klaster-klaster tersebut. Hasil penelitian ini diharapkan bermanfaat dalam merancang teknik konservasi tanah dan air untuk menangani erosi di Sub DAS Ngrancah. ABSTRACT The research was carried out at Ngrancah Sub Watershed which is located at the upper area of Sermo Dam and covers an area of almost 2.200 hectares.  The area is mostly critical showed by the high rates of erosion, so, it is  urgently required to manage properly in order to combat  land degradation. In this research, to study the erosion rates of the area, the USLE method was used, i.e. A = RxKxLSxCxP. The area was devided into 77 land units and the soil samples were taken from each land units as well as the observation of slopes, vegetation and soil conservation practices

Channel erosion in a rapidly urbanizing region of Tijuana, Mexico: Enlargement downstream of channel hardpoints

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Taniguchi, Kristine; Biggs, Trent; Langendoen, Eddy; Castillo, Carlos; Gudiño, Napoleon; Yuan, Yongping; Liden, Douglas

2016-04-01

Urban-induced erosion in Tijuana, Mexico, has led to excessive sediment deposition in the Tijuana Estuary in the United States. Urban areas in developing countries, in contrast to developed countries, are characterized by much lower proportions of vegetation and impervious surfaces due to limited access to urban services such as road paving and landscaping, and larger proportions of exposed soils. In developing countries, traditional watershed scale variables such as impervious surfaces may not be good predictors of channel enlargement. In this research, we surveyed the stream channel network of an erodible tributary of the Tijuana River Watershed, Los Laureles Canyon, at 125 locations, including repeat surveys from 2008. Structure from Motion (SfM) and 3D photo-reconstruction techniques were used to create digital terrain models of stream reaches upstream and downstream of channel hardpoints. Channels are unstable downstream of hardpoints, with incision up to 2 meters and widening up to 12 meters. Coordinated channelization is essential to avoid piece-meal approaches that lead to channel degradation. Watershed impervious area is not a good predictor of channel erosion due to the overriding importance of hardpoints and likely to the high sediment supply from the unpaved roads which prevents channel erosion throughout the stream network.

Fine sediment sources in coastal watersheds with uplifted marine terraces in northwest Humboldt County, California

Science.gov (United States)

Stephen Sungnome Madrone; Andrew P. Stubblefield

2012-01-01

Erosion in the Mill and Luffenholtz Creek watersheds in Humboldt County, California, with their extensive clay soils, can lead to high turbidity levels in receiving bodies of water, increasing the costs of treating water for domestic water supplies. Detailed road and erosion surveys and monitoring of suspended sediment, discharge, and turbidity levels in Mill Creek (3....

Prescribed Fire Effects on Runoff, Erosion, and Soil Water Repellency on Steeply-Sloped Sagebrush Rangeland over a Five Year Period

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Williams, C. J.; Pierson, F. B.; Al-Hamdan, O. Z.

2014-12-01

Fire is an inherent component of sagebrush steppe rangelands in western North America and can dramatically affect runoff and erosion processes. Post-fire flooding and erosion events pose substantial threats to proximal resources, property, and human life. Yet, prescribed fire can serve as a tool to manage vegetation and fuels on sagebrush rangelands and to reduce the potential for large catastrophic fires and mass erosion events. The impact of burning on event hydrologic and erosion responses is strongly related to the degree to which burning alters vegetation, ground cover, and surface soils and the intensity and duration of precipitation. Fire impacts on hydrologic and erosion response may be intensified or reduced by inherent site characteristics such as topography and soil properties. Parameterization of these diverse conditions in predictive tools is often limited by a lack of data and/or understanding for the domain of interest. Furthermore, hydrologic and erosion functioning change as vegetation and ground cover recover in the years following burning and few studies track these changes over time. In this study, we evaluated the impacts of prescribed fire on vegetation, ground cover, soil water repellency, and hydrologic and erosion responses 1, 2, and 5 yr following burning of a mountain big sagebrush community on steep hillslopes with fine-textured soils. The study site is within the Reynolds Creek Experimental Watershed, southwestern Idaho, USA. Vegetation, ground cover, and soil properties were measured over plot scales of 0.5 m2 to 9 m2. Rainfall simulations (0.5 m2) were used to assess the impacts of fire on soil water repellency, infiltration, runoff generation, and splash-sheet erosion. Overland flow experiments (9 m2) were used to assess the effects of fire-reduced ground cover on concentrated-flow runoff and erosion processes. The study results provide insight regarding fire impacts on runoff, erosion, and soil water repellency in the immediate and

Application of the 137Cs determination to evaluate the erosion rates in cultivated soils in the west part of Cuba

International Nuclear Information System (INIS)

Gil Castillo, Reinaldo; Peralta Vital, Jose Luis; Carrazana Gonzalez, Jorge; Riverol Rosquet, Mario; Penna Valenti, Fermin; Cabrera Calcedo, Eduardo

2004-01-01

The paper shows the experience in the application of 137Cs technique to estimate the erosion rates in cultivated soils (Ultisol) in the west part of the country, and the validation of the technique results by comparison against the results from traditional methods (watershed segments). The proportional, the simplified balance of mass and the balance of mass models were used to calculate the erosion rates, for three segments. In the evaluated area, have been obtained erosion rates from 3.5 to 7.1 t/ha/y for the segment I, from 5.17 to 10.3 t/ha/y for the segment III and from 2.3 to 17 t/ha/y for the segment IX. The conclusions are, the 137Cs technique is reliable for the estimation of erosion rates in the evaluated soil and the mass balance model obtained the nearest values to the estimated by watershed segments

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

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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.

Effects of land clearing techniques and tillage systems on runoff and soil erosion in a tropical rain forest in Nigeria.

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Ehigiator, O A; Anyata, B U

2011-11-01

This work reports runoff and soil loss from each of 14 sub-watersheds in a secondary rain forest in south-western Nigeria. The impact of methods of land clearing and post-clearing management on runoff and soil erosion under the secondary forest is evaluated. These data were acquired eighteen years after the deforestation of primary vegetation during the ' West bank' project of the International Institute for Tropical Agriculture (IITA). These data are presented separately for each season; however, statistical analyses for replicates were not conducted due to differences in their past management. Soil erosion was affected by land clearing and tillage methods. The maximum soil erosion was observed on sub-watersheds that were mechanically cleared with tree-pusher/root-rake attachments and tilled conventionally. A high rate of erosion was observed even when graded-channel terraces were constructed to minimize soil erosion. In general there was much less soil erosion on manually cleared than on mechanically cleared sub-watersheds (2.5 t ha(-1) yr(-1) versus 13.8 t ha(-1) yr(-1)) and from the application of no-tillage methods than from conventionally plowed areas (6.5 t ha(-1) yr(-1) versus 12.1 t ha(-1) yr(-1)). The data indicate that tillage methods and appropriate management of soils and crops play an important role in soil and water conservation and in decreasing the rate of decline of soil quality. Copyright © 2011 Elsevier Ltd. All rights reserved.

Conceptual model of sediment processes in the upper Yuba River watershed, Sierra Nevada, CA

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Curtis, J.A.; Flint, L.E.; Alpers, Charles N.; Yarnell, S.M.

2005-01-01

This study examines the development of a conceptual model of sediment processes in the upper Yuba River watershed; and we hypothesize how components of the conceptual model may be spatially distributed using a geographical information system (GIS). The conceptual model illustrates key processes controlling sediment dynamics in the upper Yuba River watershed and was tested and revised using field measurements, aerial photography, and low elevation videography. Field reconnaissance included mass wasting and channel storage inventories, assessment of annual channel change in upland tributaries, and evaluation of the relative importance of sediment sources and transport processes. Hillslope erosion rates throughout the study area are relatively low when compared to more rapidly eroding landscapes such as the Pacific Northwest and notable hillslope sediment sources include highly erodible andesitic mudflows, serpentinized ultramafics, and unvegetated hydraulic mine pits. Mass wasting dominates surface erosion on the hillslopes; however, erosion of stored channel sediment is the primary contributor to annual sediment yield. We used GIS to spatially distribute the components of the conceptual model and created hillslope erosion potential and channel storage models. The GIS models exemplify the conceptual model in that landscapes with low potential evapotranspiration, sparse vegetation, steep slopes, erodible geology and soils, and high road densities display the greatest hillslope erosion potential and channel storage increases with increasing stream order. In-channel storage in upland tributaries impacted by hydraulic mining is an exception. Reworking of stored hydraulic mining sediment in low-order tributaries continues to elevate upper Yuba River sediment yields. Finally, we propose that spatially distributing the components of a conceptual model in a GIS framework provides a guide for developing more detailed sediment budgets or numerical models making it an

Sustainable environmental flow management in an agricultural watershed in northeast Kansas

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Background/Question/Methods The Delaware watershed, an area of land in northeast Kansas of over 1110 square miles, has degraded water quality due to intensive cultivation of crops and subsequent nutrient enrichment and erosion. The current conditions may be further aggravated by ...

Modeling the effects of LID practices on streams health at watershed scale

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Shannak, S.; Jaber, F. H.

2013-12-01

Increasing impervious covers due to urbanization will lead to an increase in runoff volumes, and eventually increase flooding. Stream channels adjust by widening and eroding stream bank which would impact downstream property negatively (Chin and Gregory, 2001). Also, urban runoff drains in sediment bank areas in what's known as riparian zones and constricts stream channels (Walsh, 2009). Both physical and chemical factors associated with urbanization such as high peak flows and low water quality further stress aquatic life and contribute to overall biological condition of urban streams (Maxted et al., 1995). While LID practices have been mentioned and studied in literature for stormwater management, they have not been studied in respect to reducing potential impact on stream health. To evaluate the performance and the effectiveness of LID practices at a watershed scale, sustainable detention pond, bioretention, and permeable pavement will be modeled at watershed scale. These measures affect the storm peak flows and base flow patterns over long periods, and there is a need to characterize their effect on stream bank and bed erosion, and aquatic life. These measures will create a linkage between urban watershed development and stream conditions specifically biological health. The first phase of this study is to design and construct LID practices at the Texas A&M AgriLife Research and Extension Center-Dallas, TX to collect field data about the performance of these practices on a smaller scale. The second phase consists of simulating the performance of LID practices on a watershed scale. This simulation presents a long term model (23 years) using SWAT to evaluate the potential impacts of these practices on; potential stream bank and bed erosion, and potential impact on aquatic life in the Blunn Watershed located in Austin, TX. Sub-daily time step model simulations will be developed to simulate the effectiveness of the three LID practices with respect to reducing

Optimal Land Use Management for Soil Erosion Control by Using an Interval-Parameter Fuzzy Two-Stage Stochastic Programming Approach

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Han, Jing-Cheng; Huang, Guo-He; Zhang, Hua; Li, Zhong

2013-09-01

Soil erosion is one of the most serious environmental and public health problems, and such land degradation can be effectively mitigated through performing land use transitions across a watershed. Optimal land use management can thus provide a way to reduce soil erosion while achieving the maximum net benefit. However, optimized land use allocation schemes are not always successful since uncertainties pertaining to soil erosion control are not well presented. This study applied an interval-parameter fuzzy two-stage stochastic programming approach to generate optimal land use planning strategies for soil erosion control based on an inexact optimization framework, in which various uncertainties were reflected. The modeling approach can incorporate predefined soil erosion control policies, and address inherent system uncertainties expressed as discrete intervals, fuzzy sets, and probability distributions. The developed model was demonstrated through a case study in the Xiangxi River watershed, China's Three Gorges Reservoir region. Land use transformations were employed as decision variables, and based on these, the land use change dynamics were yielded for a 15-year planning horizon. Finally, the maximum net economic benefit with an interval value of [1.197, 6.311] × 109 was obtained as well as corresponding land use allocations in the three planning periods. Also, the resulting soil erosion amount was found to be decreased and controlled at a tolerable level over the watershed. Thus, results confirm that the developed model is a useful tool for implementing land use management as not only does it allow local decision makers to optimize land use allocation, but can also help to answer how to accomplish land use changes.

Optimal land use management for soil erosion control by using an interval-parameter fuzzy two-stage stochastic programming approach.

Science.gov (United States)

Han, Jing-Cheng; Huang, Guo-He; Zhang, Hua; Li, Zhong

2013-09-01

Soil erosion is one of the most serious environmental and public health problems, and such land degradation can be effectively mitigated through performing land use transitions across a watershed. Optimal land use management can thus provide a way to reduce soil erosion while achieving the maximum net benefit. However, optimized land use allocation schemes are not always successful since uncertainties pertaining to soil erosion control are not well presented. This study applied an interval-parameter fuzzy two-stage stochastic programming approach to generate optimal land use planning strategies for soil erosion control based on an inexact optimization framework, in which various uncertainties were reflected. The modeling approach can incorporate predefined soil erosion control policies, and address inherent system uncertainties expressed as discrete intervals, fuzzy sets, and probability distributions. The developed model was demonstrated through a case study in the Xiangxi River watershed, China's Three Gorges Reservoir region. Land use transformations were employed as decision variables, and based on these, the land use change dynamics were yielded for a 15-year planning horizon. Finally, the maximum net economic benefit with an interval value of [1.197, 6.311] × 10(9) $ was obtained as well as corresponding land use allocations in the three planning periods. Also, the resulting soil erosion amount was found to be decreased and controlled at a tolerable level over the watershed. Thus, results confirm that the developed model is a useful tool for implementing land use management as not only does it allow local decision makers to optimize land use allocation, but can also help to answer how to accomplish land use changes.

Advancements in Hydrology and Erosion Process Understanding and Post-Fire Hydrologic and Erosion Model Development for Semi-Arid Landscapes

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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.

Landslides and sediment budgets in four watersheds in eastern Puerto Rico: Chapter F in Water quality and landscape processes of four watersheds in eastern Puerto Rico

Science.gov (United States)

Larsen, Matthew C.; Murphy, Sheila F.; Stallard, Robert F.

2012-01-01

The low-latitude regions of the Earth are undergoing profound, rapid landscape change as forests are converted to agriculture to support growing population. Understanding the effects of these land-use changes requires analysis of watershed-scale geomorphic processes to better inform and manage this usually disorganized process. The investigation of hillslope erosion and the development of sediment budgets provides essential information for resource managers. Four small, montane, humid-tropical watersheds in the Luquillo Experimental Forest and nearby Río Grande de Loíza watershed, Puerto Rico (18° 20' N., 65° 45' W.), were selected to compare and contrast the geomorphic effects of land use and bedrock geology. Two of the watersheds are underlain largely by resistant Cretaceous volcaniclastic rocks but differ in land use and mean annual runoff: the Mameyes watershed, with predominantly primary forest cover and runoff of 2,750 millimeters per year, and the Canóvanas watershed, with mixed secondary forest and pasture and runoff of 970 millimeters per year. The additional two watersheds are underlain by relatively erodible granitic bedrock: the forested Icacos watershed, with runoff of 3,760 millimeters per year and the agriculturally developed Cayaguás watershed, with a mean annual runoff of 1,620 millimeters per year. Annual sediment budgets were estimated for each watershed using landslide, slopewash, soil creep, treethrow, suspended sediment, and streamflow data. The budgets also included estimates of sediment storage in channel beds, bars, floodplains, and in colluvial deposits. In the two watersheds underlain by volcaniclastic rocks, the forested Mameyes and the developed Canóvanas watersheds, landslide frequency (0.21 and 0.04 landslides per square kilometer per year, respectively), slopewash (5 and 30 metric tons per square kilometer per year), and suspended sediment yield (325 and 424 metric tons per square kilometer per year), were lower than in the

Compilation of watershed models for tributaries to the Great Lakes, United States, as of 2010, and identification of watersheds for future modeling for the Great Lakes Restoration Initiative

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Coon, William F.; Murphy, Elizabeth A.; Soong, David T.; Sharpe, Jennifer B.

2011-01-01

As part of the Great Lakes Restoration Initiative (GLRI) during 2009–10, the U.S. Geological Survey (USGS) compiled a list of existing watershed models that had been created for tributaries within the United States that drain to the Great Lakes. Established Federal programs that are overseen by the National Oceanic and Atmospheric Administration (NOAA) and the U.S. Army Corps of Engineers (USACE) are responsible for most of the existing watershed models for specific tributaries. The NOAA Great Lakes Environmental Research Laboratory (GLERL) uses the Large Basin Runoff Model to provide data for the management of water levels in the Great Lakes by estimating United States and Canadian inflows to the Great Lakes from 121 large watersheds. GLERL also simulates streamflows in 34 U.S. watersheds by a grid-based model, the Distributed Large Basin Runoff Model. The NOAA National Weather Service uses the Sacramento Soil Moisture Accounting model to predict flows at river forecast sites. The USACE created or funded the creation of models for at least 30 tributaries to the Great Lakes to better understand sediment erosion, transport, and aggradation processes that affect Federal navigation channels and harbors. Many of the USACE hydrologic models have been coupled with hydrodynamic and sediment-transport models that simulate the processes in the stream and harbor near the mouth of the modeled tributary. Some models either have been applied or have the capability of being applied across the entire Great Lakes Basin; they are (1) the SPAtially Referenced Regressions On Watershed attributes (SPARROW) model, which was developed by the USGS; (2) the High Impact Targeting (HIT) and Digital Watershed models, which were developed by the Institute of Water Research at Michigan State University; (3) the Long-Term Hydrologic Impact Assessment (L–THIA) model, which was developed by researchers at Purdue University; and (4) the Water Erosion Prediction Project (WEPP) model, which was

Applying online WEPP to assess forest watershed hydrology

Science.gov (United States)

S. Dun; J. Q. Wu; W. J. Elliot; J. R. Frankenberger; D. C. Flanagan; D. K. McCool

2011-01-01

The U.S. Army Corps of Engineers (USACE) and the Great Lakes Commission are developing technologies and predictive tools to aid in watershed management with an ultimate goal of improving and preserving the water quality in the Great Lakes Basin. A new version of the online Water Erosion Prediction Project (WEPP) GIS interface has been developed to assist in evaluating...

Reservoir Sedimentation and Upstream Sediment Sources: Perspectives and Future Research Needs on Streambank and Gully Erosion

Science.gov (United States)

Fox, G. A.; Sheshukov, A.; Cruse, R.; Kolar, R. L.; Guertault, L.; Gesch, K. R.; Dutnell, R. C.

2016-05-01

The future reliance on water supply and flood control reservoirs across the globe will continue to expand, especially under a variable climate. As the inventory of new potential dam sites is shrinking, construction of additional reservoirs is less likely compared to simultaneous flow and sediment management in existing reservoirs. One aspect of this sediment management is related to the control of upstream sediment sources. However, key research questions remain regarding upstream sediment loading rates. Highlighted in this article are research needs relative to measuring and predicting sediment transport rates and loading due to streambank and gully erosion within a watershed. For example, additional instream sediment transport and reservoir sedimentation rate measurements are needed across a range of watershed conditions, reservoir sizes, and geographical locations. More research is needed to understand the intricate linkage between upland practices and instream response. A need still exists to clarify the benefit of restoration or stabilization of a small reach within a channel system or maturing gully on total watershed sediment load. We need to better understand the intricate interactions between hydrological and erosion processes to improve prediction, location, and timing of streambank erosion and failure and gully formation. Also, improved process-based measurement and prediction techniques are needed that balance data requirements regarding cohesive soil erodibility and stability as compared to simpler topographic indices for gullies or stream classification systems. Such techniques will allow the research community to address the benefit of various conservation and/or stabilization practices at targeted locations within watersheds.

EVALUATION OF RAINFALL-RUNOFF EROSIVITY FACTOR FOR CAMERON HIGHLAND, PAHANG, MALAYSIA

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Abdulkadir Taofeeq Sholagberu

2016-07-01

Full Text Available Rainfall-runoff is the active agent of soil erosion which often resulted in land degradation and water quality deterioration. Its aggressiveness to induce erosion is usually termed as rainfall erosivity index or factor (R. R-factor is one of the factors to be parameterized in the evaluation of soil loss using the Universal Soil Loss Equation and its reversed versions (USLE/RUSLE. The computation of accurate R-factor for a particular watershed requires high temporal resolution rainfall (pluviograph data with less than 30-minutes intensities for at least 20 yrs, which is available only in a few regions of the world. As a result, various simplified models have been proposed by researchers to evaluate R-factor using readily available daily, monthly or annual precipitation data. This study is thus aimed at estimating R-factor and to establish an approximate relationship between R-factor and rainfall for subsequent usage in the estimation of soil loss in Cameron highlands watershed. The results of the analysis showed that the least and peak (critical R-factors occurred in the months of January and April with 660.82 and 2399.18 MJ mm ha-1 h-1year-1 respectively. Also, it was observed that erosivity power starts to increase from the month of January through April before started falling in the month of July. The monthly and annual peaks (critical periods may be attributed to increased rainfall amount due to climate change which in turn resulted to increased aggressiveness of rains to cause erosion in the study area. The correlation coefficient of 0.985 showed that there was a strong relationship rainfall and R-factor.

The spatial variance of hill slope erosion in Loess Hilly Area by 137Cs tracing method

International Nuclear Information System (INIS)

Li Mian; Yang Jianfeng; Shen Zhenzhou; Hou Jiancai

2009-01-01

Based on analysis of 137 Cs activities in soil profiles on hill slope of different slope lengths in the Loess Hilly Area in China, the spatial variance of erosion was studied. The results show that the slope length has great impact on the spatial distribution of the soil erosion intensity, and the soil erosion intensity on loess hill slope was in a fluctuating tendency. In the influx process of runoff in a small watershed, net soil loss intensity increased first and then decreased with flow distance. (authors)

Coupled analysis on landscape pattern and hydrological processes in Yanhe watershed of China.

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Li, J; Zhou, Z X

2015-02-01

As a typical experimental Soil and Water Conservation District, Yanhe watershed has long been plagued by soil erosion due to severe human disturbances. Exerting remote sensing (RS) and geographic information system (GIS) technology, this paper firstly analyzed and simulated ecological hydrological process in Yanhe watershed based on SWAT model, constructed a comprehensive landscape indices which was closely related to soil erosion, and reflected the coupling relationship between regional landscape pattern change and soil erosion. The results are as follows: (1) Areas of different land use types remained relatively stable from 1990 to 2000 and then changed drastically from 2000 to 2010, which was characterized by lawn expansion and cultivated land shrinkage. (2) In terms of the spatial heterogeneity of hydrological response unit (HRUs), the correlation coefficient of seven selected landscape indices and runoff was very small, and cannot pass all significant testing. But correlation between the indices and sediment yield except for Total Core Area (TCA) and Interspersion and Juxtaposition Index (IJI) was remarkable. (3) According to 'the source-sink' theory of soil erosion, new landscape index-slope-HRU landscape index (SHLI) was built, and reflected the relationship between landscape pattern and soil erosion processes to a certain extent. (4) Coupling relationship between SHLI in 2010 and annual sediment was very prominent. In the sub-basin scale, SHLI has obvious regional differentiation from annual sediment. Copyright © 2014 Elsevier B.V. All rights reserved.

Best Management Practices for sediment control in a Mediterranean agricultural watershed

Science.gov (United States)

Abdelwahab, Ossama M. M.; Bingner, Ronald L.; Milillo, Fabio; Gentile, Francesco

2015-04-01

Soil erosion can lead to severe destruction of agricultural sustainability that affects not only productivity, but the entire ecosystem in the neighboring areas. Sediments transported together with the associated nutrients and chemicals can significantly impact downstream water bodies. Various conservation and management practices implemented individually or integrated together as a system can be used to reduce the negative impacts on agricultural watersheds from soil erosion. Hydrological models are useful tools for decision makers when selecting the most effective combination of management practices to reduce pollutant loads within a watershed system. The Annualized Agricultural Non-point Source (AnnAGNPS) pollutant loading management model can be used to analyze the effectiveness of diverse management and conservation practices that can control or reduce the impact of soil erosion processes and subsequent sediment loads in agricultural watersheds. A 506 km2 Mediterranean medium-size watershed (Carapelle) located in Apulia, Southern Italy was used as a case study to evaluate the model and best management practices (BMPs) for sediment load control. A monitoring station located at the Ordona bridge has been instrumented to continuously monitor stream flow and suspended sediment loads. The station has been equipped with an ultrasound stage meter and a stage recorder to monitor stream flow. An infrared optic probe was used to measure suspended sediment concentrations (Gentile et al., 2010 ). The model was calibrated and validated in the Carapelle watershed on an event basis (Bisantino et al., 2013), and the validated model was used to evaluate the effectiveness of BMPs on sediment reduction. Various management practices were investigated including evaluating the impact on sediment load of: (1) converting all cropland areas into forest and grass covered conditions; (2) converting the highest eroding cropland areas to forest or grass covered conditions; and (3

Soil erosion and sedimentation rates in a small eutrophic lake in southern Chile estimated by 210Pb isotope analysis

International Nuclear Information System (INIS)

Cisternas, M.; Urrutia, R.; Araneda, A.; Debels, P.; Rios, F.

1999-01-01

The purpose of this research is to study the effects of historical land use patterns on soil erosion within the San Pedro Lake watershed (Concepcion, VIII Region, Chile). To this end, a geochronological reconstruction of the last 50 years was accomplished by 210 Pb isotope and photo-interpretation analysis through the use of GIS. The erosion rate has varied from 0.40 t ha -1 y -1 in 1955 to 0.86 t ha -1 y -1 in 1994. The decrease in native forest was closely coupled with the increase in exotic forestry. The Total Change, meaning the land use change without considering each typology, shows a constant trend indicating a greater degree of anthropogenic intervention. As opposed to the expected, there is no relationship between land use typologies and erosion rates, however it is possible to recognise some degree of dependency between Total Change and erosion values. It is concluded that over the last 50 years the soil erosion processes in the San Pedro Lake watershed may have been more regulated more by land use changes than by land use typologies themselves. (author)

Pataha Creek Model Watershed : January 2000-December 2002 Habitat Conservation Projects.

Energy Technology Data Exchange (ETDEWEB)

Bartels, Duane G.

2003-04-01

The projects outlined in detail on the attached project reports were implemented from calendar year 2000 through 2002 in the Pataha Creek Watershed. The Pataha Creek Watershed was selected in 1993, along with the Tucannon and Asotin Creeks, as model watersheds by NPPC. In previous years, demonstration sites using riparian fencing, off site watering facilities, tree and shrub plantings and upland conservation practices were used for information and education and were the main focus of the implementation phase of the watershed plan. These practices were the main focus of the watershed plan to reduce the majority of the sediment entering the stream. Prior to 2000, several bank stabilization projects were installed but the installation costs became prohibitive and these types of projects were reduced in numbers over the following years. The years 2000 through 2002 were years where a focused effort was made to work on the upland conservation practices to reduce the sedimentation into Pataha Creek. Over 95% of the sediment entering the stream can be tied directly to the upland and riparian areas of the watershed. The Pataha Creek has steelhead in the upper reaches and native and planted rainbow trout in the mid to upper portion. Suckers, pikeminow and shiners inhabit the lower portion because of the higher water temperatures and lack of vegetation. The improvement of riparian habitat will improve habitat for the desired fish species. The lower portion of the Pataha Creek could eventually develop into spawning and rearing habitat for chinook salmon if some migration barriers are removed and habitat is restored. The upland projects completed during 2000 through 2002 were practices that reduce erosion from the cropland. Three-year continuous no-till projects were finishing up and the monitoring of this particular practice is ongoing. Its direct impact on soil erosion along with the economical aspects is being studied. Other practices such as terrace, waterway, sediment

Runoff and initial erosion assessment in fruit tree crops and improved forage pastures in the slopes of the Irazu Volcano (Costa Rica)

Science.gov (United States)

Marchamalo, Miguel; González-Rodrigo, Beatriz

2017-04-01

Costa Rica is located in the Central American tropical isthmus. It presents high precipitations (ranging from 1400-8500 mm) and protection levels (27% of national territory). However, intensive land use and increasing population in headwaters are major threats for water resource management in this country. Birrís Basin is a 4800 hectares sub-watershed of the River Reventazón Basin, the major hydroelectric source in Costa Rica. Birrís Basin was selected for its high estimated erosion rates and its potential for demonstrative projects (ICE, 1999). Some pilot projects have been developed in this watershed starting from 1999, when major Costa Rican energy producer, Instituto Costarricense de Electricidad, began with a long term watershed management program for the Reventazón Basin. This study aims at measuring runoff and initial splash and sheet erosion to assess the hydrological response of two pilot land use projects. Erosion and runoff plots were established and monitored in a one year period for two pilot projects (fruit trees and forage pastures) and their respective traditional land uses (vegetable crops and extensive pastures). Improved forage pastures showed reduced runoff by 73% and split erosion by 55% compared to prior extensive pastures. Conversion of vegetable crop lands into fruit tree plantations (apricot and avocado) made possible a 97% reduction of soil initial erosion. Land use pilot projects have succeeded in runoff and soil erosion reduction. Now it is time for a wider technology transfer program to expand improved land uses within Birrís Basin.

Agriculture and stream water quality: A biological evaluation of erosion control practices

Science.gov (United States)

Lenat, David R.

1984-07-01

Agricultural runoff affects many streams in North Carolina. However, there is is little information about either its effect on stream biota or any potential mitigation by erosion control practices. In this study, benthic macroinvertebrates were sampled in three different geographic areas of North Carolina, comparing control watersheds with well-managed and poorly managed watersheds. Agricultural streams were characterized by lower taxa richness (especially for intolerant groups) and low stability. These effects were most evident at the poorly managed sites. Sedimentation was the apparent major problem, but some changes at agricultural sites implied water quality problems. The groups most intolerant of agricultural runoff were Ephemeroptera, Plecoptera and Trichoptera. Tolerant species were usually filter-feeders or algal grazers, suggesting a modification of the food web by addition of particulate organic matter and nutrients. This study clearly indicates that agricultural runoff can severely impact stream biota. However, this impact can be greatly mitigated by currently recommended erosion control practices.

Non-Fluvial Controls of Erosion, Sediment Transport and Fluvial Morphology in a mid-Atlantic Piedmont Watershed, White Clay Creek, Pennsylvania, U.S.A.

Science.gov (United States)

McCarthy, K.; Affinito, R. A.; Pizzuto, J. E.; Stotts, S.; Henry, T.; Krauthauser, M.; O'Neal, M. A.

2017-12-01

Quantifying contemporary sediment budgets is essential for restoration and ecosystem management of mid-Atlantic watersheds, but relevant processes and controls are poorly understood. In the 153 km2 White Clay Creek watershed in southeastern Pennsylvania, longitudinal profiles reflect migration of knickpoints though bedrock over Quaternary timescales. In bank exposures along stream valleys, saprolite, bedrock, and matrix-supported cobbly and bouldery diamicton (likely colluvial) commonly underlie finer-grained clay, silt, sand, and gravel deposits of valley floor depositional environments. Overbank sedimentation rates were quantified by measuring the thickness of sediment deposited over the roots of floodplain trees. The sampled trees range in age from 25-270 years with median sediment accumulation rates of approximately 2 mm/yr (range 0-10 mm/yr). Rates of bank retreat (measured from historical aerial imagery or root-exposure dendrochronology) vary from 6-36 cm/yr, with median rates of 10 cm/yr. While bank erosion rates are subject to a variety of controls, including channel curvature, the density of riparian trees, and freeze-thaw processes, the strongest influence appears to be the grain size and thickness of bouldery diamicton exposed along the toes of retreating banks. Cobbles and boulders supplied by eroding diamicton also mantle the bed of the channel, such that 33- 80% of the bed material remains immobile at bankfull stage. A conceptual model of fluvial processes and sediment budgets for these channels must account for the watershed's history of changing climate, tectonics, and land use, requiring mapping of bedrock, colluvium, former mill dam sediments, and other non-alluvial deposits and controls. Efforts to apply hydraulic geometry principles (requiring a precise adjustment to contemporary hydraulic and sediment regime) or to treat these channels as traditional "threshold" rivers are unlikely to be successful.

Geospatial application of the Water Erosion Prediction Project (WEPP) model

Science.gov (United States)

D. C. Flanagan; J. R. Frankenberger; T. A. Cochrane; C. S. Renschler; W. J. Elliot

2013-01-01

At the hillslope profile and/or field scale, a simple Windows graphical user interface (GUI) is available to easily specify the slope, soil, and management inputs for application of the USDA Water Erosion Prediction Project (WEPP) model. Likewise, basic small watershed configurations of a few hillslopes and channels can be created and simulated with this GUI. However,...

The land use patterns for soil organic carbon conservation at Endanga watershed Southeast Sulawesi Indonesia

Science.gov (United States)

Leomo, S.; Ginting, S.; Sabaruddin, L.; Tufaila, M.; Muhidin

2018-02-01

The Endanga basin is one part of the Konaweeha watershed located in South Konawe, Southeast Sulawesi Province, covering an area of 1,353.67 hectares. The land use patterns in Endanga Watershed contained forests, shrubs, oil palm plantations, pepper fields, and cultivated fields of field rice, corn monoculture and intercropping of peanuts and corn. This watershed needs serious attention because most of its territory is on slope of 15-40%, with erosion hazard levels (EHL) varying from mild erosion to severe erosion. The loss of organic carbon (C-organic) soil is measured from the soil carried along with the surface stream and into the reservoir on various land uses. The result measurement of C-organic soil loss on forest land use is 14.02 kg ha-1, shrubs land 22.71 kg ha-1, oil palm 151.32 kg ha-1, pepper garden 93.69 kg ha-1, field rice 313.80 kg.ha-1, monoculture of maize 142.44 kg ha-1, intercropped maize and corn 51.10 kg ha-1 and open land 1,909.16 kg ha-1. The forest land and shrubs is best in conserving soil C-organic, but economically unfavorable for the community, so land use pattern for intercropping and pepper plantation can be used for soil C-organic conservation

Soil erodibility for water erosion: A perspective and Chinese experiences

Science.gov (United States)

Wang, Bin; Zheng, Fenli; Römkens, Mathias J. M.; Darboux, Frédéric

2013-04-01

Knowledge of soil erodibility is an essential requirement for erosion prediction, conservation planning, and the assessment of sediment related environmental effects of watershed agricultural practices. This paper reviews the status of soil erodibility evaluations and determinations based on 80 years of upland area erosion research mainly in China and the USA. The review synthesizes the general research progress made by discussing the basic concepts of erodibility and its evaluation, determination, and prediction as well as knowledge of its spatio-temporal variations. The authors found that soil erodibility is often inappropriately or inaccurately applied in describing soil loss caused by different soil erosion component processes and mechanisms. Soil erodibility indicators were related to intrinsic soil properties and exogenic erosional forces, measurements, and calculations. The present review describes major needs including: (1) improved definition of erodibility, (2) modified erodibility determinations in erosion models, especially for specific geographical locations and in the context of different erosion sub-processes, (3) advanced methodologies for quantifying erodibilities of different soil erosion sub-processes, and (4) a better understanding of the mechanism that causes temporal variations in soil erodibility. The review also provides a more rational basis for future research on soil erodibility and supports predictive modeling of soil erosion processes and the development of improved conservation practices.

Critical shear stress for erosion of cohesive soils subjected to temperatures typical of wildfires

Science.gov (United States)

Moody, J.A.; Dungan, Smith J.; Ragan, B.W.

2005-01-01

[1] Increased erosion is a well-known response after wildfire. To predict and to model erosion on a landscape scale requires knowledge of the critical shear stress for the initiation of motion of soil particles. As this soil property is temperature-dependent, a quantitative relation between critical shear stress and the temperatures to which the soils have been subjected during a wildfire is required. In this study the critical shear stress was measured in a recirculating flume using samples of forest soil exposed to different temperatures (40??-550??C) for 1 hour. Results were obtained for four replicates of soils derived from three different types of parent material (granitic bedrock, sandstone, and volcanic tuffs). In general, the relation between critical shear stress and temperature can be separated into three different temperature ranges (275??C), which are similar to those for water repellency and temperature. The critical shear stress was most variable (1.0-2.0 N m-2) for temperatures 2.0 N m-2) between 175?? and 275??C, and was essentially constant (0.5-0.8 N m-2) for temperatures >275??C. The changes in critical shear stress with temperature were found to be essentially independent of soil type and suggest that erosion processes in burned watersheds can be modeled more simply than erosion processes in unburned watersheds. Wildfire reduces the spatial variability of soil erodibility associated with unburned watersheds by eliminating the complex effects of vegetation in protecting soils and by reducing the range of cohesion associated with different types of unburned soils. Our results indicate that modeling the erosional response after a wildfire depends primarily on determining the spatial distribution of the maximum soil temperatures that were reached during the wildfire. Copyright 2005 by the American Geophysical Union.

Overland erosion of uranium-mill-tailings impoundments: physical processes and computational methods

International Nuclear Information System (INIS)

Walters, M.H.

1983-03-01

The surface runoff and erosional processes of watersheds caused by rainfall-runoff are reviewed. Soil properties, topography, and rainstorm distribution are discussed with respect to their effects on soil erosion. The effects of climate and vegetation are briefly presented. Regression models and physical process simulation models are reviewed

The effects of green infrastructure on exceedance of critical shear stress in Blunn Creek watershed

Science.gov (United States)

Shannak, Sa'd.

2017-10-01

Green infrastructure (GI) has attracted city planners and watershed management professional as a new approach to control urban stormwater runoff. Several regulatory enforcements of GI implementation created an urgent need for quantitative information on GI practice effectiveness, namely for sediment and stream erosion. This study aims at investigating the capability and performance of GI in reducing stream bank erosion in the Blackland Prairie ecosystem. To achieve the goal of this study, we developed a methodology to represent two types of GI (bioretention and permeable pavement) into the Soil Water Assessment Tool, we also evaluated the shear stress and excess shear stress for stream flows in conjunction with different levels of adoption of GI, and estimated potential stream bank erosion for different median soil particle sizes using real and design storms. The results provided various configurations of GI schemes in reducing the negative impact of urban stormwater runoff on stream banks. Results showed that combining permeable pavement and bioretention resulted in the greatest reduction in runoff volumes, peak flows, and excess shear stress under both real and design storms. Bioretention as a stand-alone resulted in the second greatest reduction, while the installation of detention pond only had the least reduction percentages. Lastly, results showed that the soil particle with median diameter equals to 64 mm (small cobbles) had the least excess shear stress across all design storms, while 0.5 mm (medium sand) soil particle size had the largest magnitude of excess shear stress. The current study provides several insights into a watershed scale for GI planning and watershed management to effectively reduce the negative impact of urban stormwater runoff and control streambank erosion.

Spatial model of land use change related to sediment yield (case study: Cipeles and Cilutung watershed, West Java)

Science.gov (United States)

Wulandari, D. W.; Kusratmoko, E.; Indra, T. L.

2018-05-01

Land use changes (LUC) as a result of increasing human need for space are likely to destroy the hydrological function of the watershed, increase land degradation, stimulate erosion and drive the process of sedimentation. This study aimed to predict LUC during the period 1990 to 2030 in relation to sediment yield in Cilutung and Cipeles Watershed, West Java. LUC were simulated following the model of Cellular Automata-Marcov Chain, whereas land use composition in 2030 was predicted using Land Change Modeler on Idrisi Selva Software. Elevation, slope, distance from road, distance from river, and distance from settlement were selected as driving factors for LUC in this study. Erosion and sediment yield were predicted using WATEM/SEDEM model based on land use, rainfall, soil texture and topography. The results showed that the areas of forest and shrub have slightly declined up to 5% during the period 1990 to 2016, generally being converted into rice fields, settlements, non-irrigated fields and plantations. In addition, rice fields, settlements, and plantations were expected to substantially increase up to 50% in 2030. Furthermore, the study also revealed that erosion and sediment yield tend to increase every year. This is likely associated with LUC occurring in Cipeles and Cilutung Watershed.

Determination of Watershed Infiltration and Erosion Parameters from Field Rainfall Simulation Analyses

Directory of Open Access Journals (Sweden)

Mark E. Grismer

2016-06-01

Full Text Available Realistic modeling of infiltration, runoff and erosion processes from watersheds requires estimation of the effective hydraulic conductivity (Km of the hillslope soils and how it varies with soil tilth, depth and cover conditions. Field rainfall simulation (RS plot studies provide an opportunity to assess the surface soil hydraulic and erodibility conditions, but a standardized interpretation and comparison of results of this kind from a wide variety of test conditions has been difficult. Here, we develop solutions to the combined set of time-to-ponding/runoff and Green– Ampt infiltration equations to determine Km values from RS test plot results and compare them to the simpler calculation of steady rain minus runoff rates. Relating soil detachment rates to stream power, we also examine the determination of “erodibility” as the ratio thereof. Using data from over 400 RS plot studies across the Lake Tahoe Basin area that employ a wide range of rain rates across a range of soil slopes and conditions, we find that the Km values can be determined from the combined infiltration equation for ~80% of the plot data and that the laminar flow form of stream power best described a constant “erodibility” across a range of volcanic skirun soil conditions. Moreover, definition of stream power based on laminar flows obviates the need for assumption of an arbitrary Mannings “n” value and the restriction to mild slopes (<10%. The infiltration equation based Km values, though more variable, were on average equivalent to that determined from the simpler calculation of steady rain minus steady runoff rates from the RS plots. However, these Km values were much smaller than those determined from other field test methods. Finally, we compare RS plot results from use of different rainfall simulators in the basin and demonstrate that despite the varying configurations and rain intensities, similar erodibilities were determined across a range of

Legacy effects of colonial millponds on floodplain sedimentation, bank erosion, and channel morphology, MID-Atlantic, USA

Science.gov (United States)

Schenk, E.R.; Hupp, C.R.

2009-01-01

Many rivers and streams of the Mid-Atlantic Region, United States (U.S.) have been altered by postcolonial floodplain sedimentation (legacy sediment) associated with numerous milldams. Little Conestoga Creek, Pennsylvania, a tributary to the Susquehanna River and the Chesapeake Bay, is one of these streams. Floodplain sedimentation rates, bank erosion rates, and channel morphology were measured annually during 2004-2007 at five sites along a 28-km length of Little Conestoga Creek with nine colonial era milldams (one dam was still in place in 2007). This study was part of a larger cooperative effort to quantify floodplain sedimentation, bank erosion, and channel morphology in a high sediment yielding region of the Chesapeake Bay watershed. Data from the five sites were used to estimate the annual volume and mass of sediment stored on the floodplain and eroded from the banks for 14 segments along the 28-km length of creek. A bank and floodplain reach based sediment budget (sediment budget) was constructed for the 28 km by summing the net volume of sediment deposited and eroded from each segment. Mean floodplain sedimentation rates for Little Conestoga Creek were variable, with erosion at one upstream site (-5 mm/year) to deposition at the other four sites (highest = 11 mm/year) despite over a meter of floodplain aggradation from postcolonial sedimentation. Mean bank erosion rates range between 29 and 163 mm/year among the five sites. Bank height increased 1 m for every 10.6 m of channel width, from upstream to downstream (R2 = 0.79, p channel and the floodplain. Floodplain sedimentation and bank erosion rates also appear to be affected by the proximity of the segments to one existing milldam, which promotes deposition upstream and scouring downstream. The floodplain and bank along the 28-km reach produced a net mean sediment loss of 5,634 Mg/year for 2004-2007, indicating that bank erosion was exceeding floodplain sedimentation. In particular, the three segments

Morphometric analysis of sub-watershed in parts of Western Ghats, South India using ASTER DEM

Directory of Open Access Journals (Sweden)

Evangelin Ramani Sujatha

2015-05-01

Full Text Available Morphometric analysis is a key to understand the hydrological process and hence is a prerequisite for the assessment of hydrological characteristics of surface water basin. Morphometric analysis to determine the drainage characteristics of Palar sub-watershed, a part of Shanmukha watershed in the Amaravati sub-catchment is done using Advanced Space-borne Thermal Emission and Reflection Global Digital Elevation Model (ASTER GDEM data, and is supplemented with topographical maps in geographical information systems platform. This study uses ASTER GDEM data to extract morphometric features of a mountain stream at micro-watershed level. The sub-watershed is divided into six micro-watersheds. The sub-watershed includes a sixth-order stream. Lower stream orders, in particular first-order streams, dominate the sub-watershed. Development of stream segments is controlled by slope and local relief. Drainage pattern of the sub-watershed and micro-watersheds is dendritic in general. The mean bifurcation ratio of the sub-watershed is 3.69 but its variation between the various stream orders suggests structural control in the development of stream network. The shape factors reveal the elongation of the sub-watershed and micro-watersheds.The relief ratio reveals the high discharge capability of the sub-watershed and meagre groundwater potential. This study is a useful tool for planning strategies in control of soil erosion and soil conservation.

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.

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.

Multitemporal analysis of estimated soil loss for the river Mourão watershed, Paraná - Brazil.

Science.gov (United States)

Graça, C H; Passig, F H; Kelniar, A R; Piza, M A; Carvalho, K Q; Arantes, E J

2015-12-01

The multitemporal behavior of soil loss by surface water erosion in the hydrographic basin of the river Mourão in the center-western region of the Paraná state, Brazil, is analyzed. Forecast was based on the application of the Universal Soil Loss Equation (USLE) with the data integration and estimates within an Geography Information System (GIS) environment. Results had shown high mean annual rain erosivity (10,000 MJ.mm.ha(-1).h(-1).year(-1)), with great concentration in January and December. As a rule, soils have average erodibilities, exception of Dystroferric Red Latisol (low class) and Dystrophic Red Argisol (high class). Although the topographic factor was high (>20), rates lower than 1 were predominant. Main land uses comprise temporal crops and pasture throughout the years. The watershed showed a natural potential for low surface erosion. When related to usage types, yearly soil loss was also low (Soil loss over the years did not provide great distinctions in distribution standards, although it becames rather intensified in some sectors, especially in the center-eastern and southwestern sections of the watershed.

North Fork Feather River Erosion Control Program

International Nuclear Information System (INIS)

Harrison, L.

1991-01-01

PG and E, an investor owned gas and electric utility serving northern and central California, has been engaged since 1984 in the development and implementation of a regional erosion control program for the 954 square mile northern Sierra Nevada watersheed of the East Branch of the North Fork Feather River in Plumas County, California. PG and E entered into an agreement with 13 governmental agencies and a number of private landowners using Coordinated Resource Management and Planning: to cooperatively develop, fund and implement the program. The group has completed several field projects and has a number of additional projects in various stages of development. This paper reports that the program provides multiple environmental and economic benefits including reduction of soil erosion and sedimentation, improved fisheries, enhancement of riparian habitat, increased land values, improved recreation opportunities, and preservation of watershed resources

14C as a tool for evaluating riverine POC sources and erosion of the Zhujiang (Pearl River) drainage basin, South China

International Nuclear Information System (INIS)

Wei Xiuguo; Yi Weixi; Shen Chengde; Yechieli, Yoseph; Li Ningli; Ding Ping; Wang Ning; Liu Kexin

2010-01-01

Radiocarbon can serve as a powerful tool for identifying sources of organic carbon and evaluating the erosion intensity in river drainage basins. In this paper we present 14 C-AMS measurements of particulate organic carbon (POC) collected from the three major tributaries of the Zhujiang (Pearl River) system: the Xijiang (Western River), Beijiang (Northern River) and Dongjiang (Eastern River) rivers. Furthermore, we discuss the distribution of POC 14 C apparent ages and the related watersheds erosion of these rivers. Results yield Δ 14 C values of -425 per mille to -65 per mille which indicate that the 14 C apparent ages of suspended POC in the entire area are in the range of 540-4445 years. The POC apparent ages from Xijiang are mostly between 2000 and 4000 years, while in Dongjiang they mostly range from 540 to 1010 years. These 14 C apparent ages indicate that the watershed erosion of the Xijiang is more severe than that of the Dongjiang. This is in agreement with other data showing deeper erosion in Xijiang due to human activities.

Distributed modeling of radiocesium washoff from the experimental watershed plots of the Fukushima fallout zone

Science.gov (United States)

Kivva, Sergei; Zheleznyak, Mark; Konoplev, Alexei; Nanba, Kenji; Onda, Yuichi; Wakiyama Yoshifumi Wakiyama, Yoshifumi

2015-04-01

The distributed hydrological "rainfall- runoff" models provide possibilities of the physically based simulation of surface and subsurface flow on watersheds based on the GIS processed data. The success of such modeling approaches for the predictions of the runoff and soil erosion provides a basis for the implementation of the distributed models of the radionuclide washoff from the watersheds. The field studies provided on the Chernobyl and Fukushima catchments provides a unique data sets for the comparative testing and improvements of the modeling tools for the watersheds located in the areas of the very different geographical and hydro-meteorological condition The set of USLE experimental plots has been established by CRIED, University of Tsukuba after the Fukushima accident to study soil erosion and 137Cs wash off from the watersheds (Onda et al, 2014). The distributed watershed models of surface and subsurface flow, sediment and radionuclide transport has been used to simulate the radionuclide transport in the basin Dnieper River, Ukraine and the watersheds of Prefecture Fuksuhima. DHSVM-R is extension of the distributed hydrological model DHSVM (Lettenmayer, Wigmosta et al, 1996-2014) by the including into it the module of the watershed radionuclide transport. DHSVM is a physically based, distributed hydrology-vegetation model for complex terrain based on the numerical solution of the network of one-dimensional equations. The surface flow submodel of DHSMV has been modified: four-directions schematization for the model's cells has been replaced by the eight-directions scheme, more numerically efficient finite -differences scheme was implemented. The new module of radionuclide wash-off from catchment and transport via stream network in soluble phase and on suspended sediments including bottom-water exchange processes was developed for DHSMV-R. DHSVM-R was implemented recently within Swedish- Ukrainian ENSURE project for the modeling of 234U wash-off from the

Rapid Assessment of Logging-Associated Sediment-Delivery Pathways in an Intensively-Managed Forested Watershed in the Southern Cascades, Northern California

Science.gov (United States)

Coe, D. B.; Wopat, M. A.; Lindsay, D.; Stanish, S.; Boone, M.; Beck, B.; Wyman, A.; Bull, J.

2012-12-01

The potential for water-quality impacts in intensively-managed forested watersheds depends partly upon the frequency of overland flow paths linking logging-related hillslope sediment sources to the channel network, as well as the volume of sediment delivered along these flow paths. In response to public concerns over perceived water-quality impacts from clearcut timber harvesting, the Battle Creek Task Force, composed of subject-matter experts from 4 different state agencies, performed a rapid assessment for visible evidence of sediment delivery pathways from multiple logging-associated features in the upper Battle Creek watershed - an area underlain predominantly by Holocene- and Late Pleistocene-aged volcanic rock types, with highly permeable soils, and relatively few streams. Logging-associated features were selected for assessment based on erosion potential and proximity to stream channels. Identified sediment-delivery pathways were then characterized by dominant erosion process and the relative magnitude of sediment delivery (i.e., low, moderate, and high) was estimated. Approximately 26 km of stream buffers adjacent to 55 clearcut harvest units were assessed, and the single detected instance of sediment delivery was found to be of low magnitude and the result of illegal encroachment by logging equipment into a 5-m wide stream-adjacent equipment-limitation zone. The proportion of sampled sites delivering sediment was found to be highest for tractor-stream crossings, followed by road-stream crossings, stream-adjacent road segments, stream-adjacent landings, and clearcut harvest units, respectively. All 5 tractor-stream crossings delivered sediment, but were generally delivering a low magnitude of sediment derived from sheetwash and rilling. Road-stream crossings (n=39) and stream-adjacent road segments (n=24) delivered observable sediment 69 and 67 percent of the time, respectively. The highest magnitudes of sediment delivery from roads were associated with

Design and impact assessment of watershed investments: An approach based on ecosystem services and boundary work

Energy Technology Data Exchange (ETDEWEB)

Adem Esmail, Blal, E-mail: blal.ademesmail@unitn.it; Geneletti, Davide

2017-01-15

Watershed investments, whose main aim is to secure water for cities, represent a promising opportunity for large-scale sustainability transitions in the near future. If properly designed, they promote activities in the watershed that enhance ecosystem services while protecting nature and biodiversity, as well as achieving other societal goals. In this paper, we build on the concepts of ecosystem services and boundary work, to develop and test an operative approach for designing and assessing the impact of watershed investments. The approach is structured to facilitate negotiations among stakeholders. Its strategic component includes setting the agenda; defining investment scenarios; and assessing the performance of watershed investments as well as planning for a follow-up. Its technical component concerns data processing; tailoring spatially explicit ecosystem service models; hence their application to design a set of “investment portfolios”, generate future land use scenarios, and model impacts on selected ecosystem services. A case study illustrates how the technical component can be developed in a data scarce context in sub-Saharan Africa in a way that is functional to support the steps of the strategic component. The case study addresses soil erosion and water scarcity-related challenges affecting Asmara, a medium-sized city in Eritrea, and considers urban water security and rural poverty alleviation as two illustrative objectives, within a ten-year planning horizon. The case study results consist in spatially explicit data (investment portfolio, land use scenario, impact on ecosystem services), which were aggregated to quantitatively assess the performance of different watershed investments scenarios, in terms of changes in soil erosion control. By addressing stakeholders' concerns of credibility, saliency, and legitimacy, the approach is expected to facilitate negotiation of objectives, definition of scenarios, and assessment of alternative watershed

Design and impact assessment of watershed investments: An approach based on ecosystem services and boundary work

International Nuclear Information System (INIS)

Adem Esmail, Blal; Geneletti, Davide

2017-01-01

Watershed investments, whose main aim is to secure water for cities, represent a promising opportunity for large-scale sustainability transitions in the near future. If properly designed, they promote activities in the watershed that enhance ecosystem services while protecting nature and biodiversity, as well as achieving other societal goals. In this paper, we build on the concepts of ecosystem services and boundary work, to develop and test an operative approach for designing and assessing the impact of watershed investments. The approach is structured to facilitate negotiations among stakeholders. Its strategic component includes setting the agenda; defining investment scenarios; and assessing the performance of watershed investments as well as planning for a follow-up. Its technical component concerns data processing; tailoring spatially explicit ecosystem service models; hence their application to design a set of “investment portfolios”, generate future land use scenarios, and model impacts on selected ecosystem services. A case study illustrates how the technical component can be developed in a data scarce context in sub-Saharan Africa in a way that is functional to support the steps of the strategic component. The case study addresses soil erosion and water scarcity-related challenges affecting Asmara, a medium-sized city in Eritrea, and considers urban water security and rural poverty alleviation as two illustrative objectives, within a ten-year planning horizon. The case study results consist in spatially explicit data (investment portfolio, land use scenario, impact on ecosystem services), which were aggregated to quantitatively assess the performance of different watershed investments scenarios, in terms of changes in soil erosion control. By addressing stakeholders' concerns of credibility, saliency, and legitimacy, the approach is expected to facilitate negotiation of objectives, definition of scenarios, and assessment of alternative watershed

Spatial and temporal analysis of natural resources degradation in the Likodra River watershed

Directory of Open Access Journals (Sweden)

Polovina Siniša

2016-01-01

Full Text Available Soil is an important natural resource whose proper use requires a good knowledge of all endogenous and exogenous factors that cause different types of degradation. Erosion is one of the forms of soil degradation. Erosion processes are characterized by a distinctive complexity and the factors affecting them are dynamics and change in space and time. A complex system degradation requires a multidisciplinary approach to the use of modern methods and techniques. Today, a large number of models are available for the assessment of soil loss through erosion as well as the levels of risk from erosion, today. Most of these are based on the logics of GIS thanks to its ability to sublimate heterogeneous information. In this paper, the analysis of spatial and temporal degradation of natural resources is carried out in the Likodra River watershed. The Likodra River is located in the northwestern part of the Republic of Serbia, and is positioned in the municipality of Krupanj. The main stream in the immediate vicinity of the town of Krupanj formed from four small streams that have expressed torrential character (the Bogoštica with the Kržava and the Čađavica with the Brštica. In May 2014, the urban area and rural parts of the municipality Krupanj were affected by catastrophic flash floods that resulted in the loss of human lives and enormous material damage. Soil degradation in the study area was analyzed using the Erosion Potential Method (EPM. The method is characterized by a high degree of reliability for determining the intensity of erosion, calculation of sediment yield and transport. The advantage of this method compared to other methods its lower complexity in terms of quantity of input parameters, simplicity and the possibility of application in GIS. In addition, the method has the advantage of choice, because it was developed in this area. The method is based on the analytical processing of data on factors affecting erosion. As the erosion

Influence of Gully Erosion Control on Amphibian and Reptile Communities within Riparian Zones of Channelized Streams

Science.gov (United States)

Riparian zones of streams in northwestern Mississippi have been impacted by agriculture, channelization, channel incision, and gully erosion. Riparian gully formation has resulted in the fragmentation of remnant riparian zones within agricultural watersheds. One widely used conservation practice for...

A method to assess soil erosion from smallholder farmers' fields: a case study from Malawi.

Science.gov (United States)

Mohamoud, Yusuf M

2013-09-01

Soil erosion by water is a major threat to sustainable food production systems in Africa. This study presents a qualitative soil erosion assessment method that links the number of broken ridges (NBRS) observed on a smallholder farmer's field after a rain event to factors of soil erosion (e.g., rainfall intensity, slope steepness, crop canopy height, and conservation practice) and to soil loss data measured from a runoff plot and receiving small streams. The assessment method consists of a rapid survey of smallholder farmers combined with field monitoring. Results show an indirect relationship between NBRS and factors of soil erosion. Results also show a direct relationship between NBRS and suspended sediment concentrations measured from an experimental runoff plot and receiving streams that drain the sub-watersheds where farmers' fields are located. Given the limited human and financial resources available to soil erosion research in developing countries, monitoring NBRS is a simple, cost-effective, and reliable erosion assessment method for regions where smallholder farmers practice contour ridging.

Relationship between soil 137Cs inventories and chemical properties in a small intensively cropped watershed

International Nuclear Information System (INIS)

Mabit, L.

1998-01-01

After estimating and spatializing the erosion risks in a small agricultural watershed in northeastern France in a previous study, the authors investigate the quality of eroding soils. Soil erosion is a selective process, exporting the finest particles, and associated chemical elements, in a preferential way. Consequently, the spatial redistribution of soil should translate into the depletion of soil in eroding areas and its enrichment in deposition sectors. Of the fifteen elements considered in this study, only organic matter confirms this hypothesis. A significant correlation was found between the soil 137 Cs (indicative of the severity of erosion) and organic matter contents. This result suggests that erosion is a redistribution process that may influence the productivity of agricultural systems on the mid/long term. (authors)

[New paradigm for soil and water conservation: a method based on watershed process modeling and scenario analysis].

Science.gov (United States)

Zhu, A-Xing; Chen, La-Jiao; Qin, Cheng-Zhi; Wang, Ping; Liu, Jun-Zhi; Li, Run-Kui; Cai, Qiang-Guo

2012-07-01

With the increase of severe soil erosion problem, soil and water conservation has become an urgent concern for sustainable development. Small watershed experimental observation is the traditional paradigm for soil and water control. However, the establishment of experimental watershed usually takes long time, and has the limitations of poor repeatability and high cost. Moreover, the popularization of the results from the experimental watershed is limited for other areas due to the differences in watershed conditions. Therefore, it is not sufficient to completely rely on this old paradigm for soil and water loss control. Recently, scenario analysis based on watershed modeling has been introduced into watershed management, which can provide information about the effectiveness of different management practices based on the quantitative simulation of watershed processes. Because of its merits such as low cost, short period, and high repeatability, scenario analysis shows great potential in aiding the development of watershed management strategy. This paper elaborated a new paradigm using watershed modeling and scenario analysis for soil and water conservation, illustrated this new paradigm through two cases for practical watershed management, and explored the future development of this new soil and water conservation paradigm.

Morphological dynamics of gully systems in the subhumid Ethiopian Highlands: the Debre Mawi watershed

Science.gov (United States)

Zegeye, Assefa D.; Langendoen, Eddy J.; Stoof, Cathelijne R.; Tilahun, Seifu A.; Dagnew, Dessalegn C.; Zimale, Fasikaw A.; Guzman, Christian D.; Yitaferu, Birru; Steenhuis, Tammo S.

2016-09-01

Gully expansion in the Ethiopian Highlands dissects vital agricultural lands with the eroded materials adversely impacting downstream resources, for example as they accumulate in reservoirs. While gully expansion and rehabilitation have been more extensively researched in the semiarid region of Ethiopia, few studies have been conducted in the (sub)humid region. For that reason, we assessed the severity of gully erosion by measuring the expansion of 13 selected permanent gullies in the subhumid Debre Mawi watershed, 30 km south of Lake Tana, Ethiopia. In addition, the rate of expansion of the entire drainage network in the watershed was determined using 0.5 m resolution aerial imagery from flights in 2005 and 2013. About 0.6 Mt (or 127 t ha-1 yr-1) of soil was lost during this period due to actively expanding gullies. The net gully area in the entire watershed increased more than 4-fold from 4.5 ha in 2005 to 20.4 ha in 2013 (> 3 % of the watershed area), indicating the growing severity of gully erosion and hence land degradation in the watershed. Soil losses were caused by upslope migrating gully heads through a combination of gully head collapse and removal of the failed material by runoff. Collapse of gully banks and retreat of headcuts was most severe in locations where elevated groundwater tables saturated gully heads and banks, destabilizing the soils by decreasing the shear strength. Elevated groundwater tables were therefore the most important cause of gully expansion. Additional factors that strongly relate to bank collapse were the height of the gully head and the size of the drainage area. Soil physical properties (e.g., texture and bulk density) only had minor effects. Conservation practices that address factors controlling erosion are the most effective in protecting gully expansion. These consist of lowering water table and regrading the gully head and sidewalls to reduce the occurrence of gravity-induced mass failures. Planting

Assessment of the Efficiency of Sediment Deposition Reduction in the Zengwen River Watershed in Taiwan

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Wu, M.; Tan, H. N.; Lo, W. C.; Tsai, C. T.

2015-12-01

The river upstream of watersheds in Taiwan is very steep, where soil and rock are often unstable so that the river watershed typically has the attribute of high sand yield and turbid runoff due to the excessive erosion in the heavy rainfall seasons. If flood water overflows the river bank, it would lead to a disaster in low-altitude plains. When flood retards or recesses, fine sediment would deposit. Over recent decades, many landslides arise in the Zengwen river watershed due to climate changes, earthquakes, and typhoons. The rocks and sands triggered by these landslides would move to the river channel through surface runoff, which may induce sediment disasters and also render an impact on the stability and sediment transport of the river channel. The risk of the sediment disaster could be reduced by implementing dredging works. However, because of the nature of the channel, the dredged river sections may have sediment depositions back; thus, causing an impact on flood safety. Therefore, it is necessary to evaluate the effectiveness of dredged works from the perspectives of hydraulic, sediment transport, and flood protection to achieve the objective of both disaster prevention and river bed stability. We applied the physiographic soil erosion-deposition (PSED) model to simulate the sediment yield, the runoff, and sediment transport rate of the Zengwen river watershed corresponding to one-day rainstorms of the return periods of 25, 50, and 100 year. The potential of sediment deposition and erosion in the river sections of the Zengwen river could be simulated by utilizing the alluvial river-movable bed two dimensional (ARMB-2D) model. The results reveal that the tendency for the potential of river sediment deposition and erosion obtained from these two models is agreeable. Furthermore, in order to evaluate the efficiency of sediment deposition reduction, two quantized values, the rate of sediment deposition reduction and the ratio of sediment deposition reduction

The impact of watershed management on coastal morphology: A case study using an integrated approach and numerical modeling

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Samaras, Achilleas G.; Koutitas, Christopher G.

2014-04-01

Coastal morphology evolves as the combined result of both natural- and human- induced factors that cover a wide range of spatial and temporal scales of effect. Areas in the vicinity of natural stream mouths are of special interest, as the direct connection with the upstream watershed extends the search for drivers of morphological evolution from the coastal area to the inland as well. Although the impact of changes in watersheds on the coastal sediment budget is well established, references that study concurrently the two fields and the quantification of their connection are scarce. In the present work, the impact of land-use changes in a watershed on coastal erosion is studied for a selected site in North Greece. Applications are based on an integrated approach to quantify the impact of watershed management on coastal morphology through numerical modeling. The watershed model SWAT and a shoreline evolution model developed by the authors (PELNCON-M) are used, evaluating with the latter the performance of the three longshore sediment transport rate formulae included in the model formulation. Results document the impact of crop abandonment on coastal erosion (agricultural land decrease from 23.3% to 5.1% is accompanied by the retreat of ~ 35 m in the vicinity of the stream mouth) and show the effect of sediment transport formula selection on the evolution of coastal morphology. Analysis denotes the relative importance of the parameters involved in the dynamics of watershed-coast systems, and - through the detailed description of a case study - is deemed to provide useful insights for researchers and policy-makers involved in their study.

Transport mechanisms of soil-bound mercury in the erosion process during rainfall-runoff events.

Science.gov (United States)

Zheng, Yi; Luo, Xiaolin; Zhang, Wei; Wu, Xin; Zhang, Juan; Han, Feng

2016-08-01

Soil contamination by mercury (Hg) is a global environmental issue. In watersheds with a significant soil Hg storage, soil erosion during rainfall-runoff events can result in nonpoint source (NPS) Hg pollution and therefore, can extend its environmental risk from soils to aquatic ecosystems. Nonetheless, transport mechanisms of soil-bound Hg in the erosion process have not been explored directly, and how different fractions of soil organic matter (SOM) impact transport is not fully understood. This study investigated transport mechanisms based on rainfall-runoff simulation experiments. The experiments simulated high-intensity and long-duration rainfall conditions, which can produce significant soil erosion and NPS pollution. The enrichment ratio (ER) of total mercury (THg) was the key variable in exploring the mechanisms. The main study findings include the following: First, the ER-sediment flux relationship for Hg depends on soil composition, and no uniform ER-sediment flux function exists for different soils. Second, depending on soil composition, significantly more Hg could be released from a less polluted soil in the early stage of large rainfall events. Third, the heavy fraction of SOM (i.e., the remnant organic matter coating on mineral particles) has a dominant influence on the enrichment behavior and transport mechanisms of Hg, while clay mineral content exhibits a significant, but indirect, influence. The study results imply that it is critical to quantify the SOM composition in addition to total organic carbon (TOC) for different soils in the watershed to adequately model the NPS pollution of Hg and spatially prioritize management actions in a heterogeneous watershed. Copyright © 2016 Elsevier Ltd. All rights reserved.

3D Agro-ecological Land Use Planning Using Surfer Tool for Sustainable Land Management in Sumani Watershed, West Sumatra Indonesia

OpenAIRE

Aflizar; Alarima Cornelius Idowu; Roni Afrizal; Jamaluddin; Husnain; Tsugiyuki Masunaga; Edi Syafri; Muzakir

2013-01-01

Estimation of soil erosion 3D (E3D) provides basic information that can help manage agricultural areas sustainably, which has not been sufficiently conducted in Indonesia. Sumani watershed is main rice production area in West Sumatra which has experienced environmental problem such as soil erosion and production problem in recent years. 3D Agro-ecological land use planning based on soil erosion 3D hazard and economic feasibility analyses consist of production cost and prize data for each crop...

IN SITU MEASUREMENT OF BEDROCK EROSION

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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

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

Soil erosion-runoff relationships: insights from laboratory studies

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Mamedov, Amrakh; Warrington, David; Levy, Guy

2016-04-01

Understanding the processes and mechanisms affecting runoff generation and subsequent soil erosion in semi-arid regions is essential for the development of improved soil and water conservation management practices. Using a drip type laboratory rain simulator, we studied runoff and soil erosion, and the relationships between them, in 60 semi-arid region soils varying in their intrinsic properties (e.g., texture, organic matter) under differing extrinsic conditions (e.g., rain properties, and conditions prevailing in the field soil). Both runoff and soil erosion were significantly affected by the intrinsic soil and rain properties, and soil conditions within agricultural fields or watersheds. The relationship between soil erosion and runoff was stronger when the rain kinetic energy was higher rather than lower, and could be expressed either as a linear or exponential function. Linear functions applied to certain limited cases associated with conditions that enhanced soil structure stability, (e.g., slow wetting, amending with soil stabilizers, minimum tillage in clay soils, and short duration exposure to rain). Exponential functions applied to most of the cases under conditions that tended to harm soil stability (e.g., fast wetting of soils, a wide range of antecedent soil water contents and rain kinetic energies, conventional tillage, following biosolid applications, irrigation with water of poor quality, consecutive rain simulations). The established relationships between runoff and soil erosion contributed to a better understanding of the mechanisms governing overland flow and soil loss, and could assist in (i) further development of soil erosion models and research techniques, and (ii) the design of more suitable management practices for soil and water conservation.

Predicting watershed post-fire sediment yield with the InVEST sediment retention model: Accuracy and uncertainties

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Sankey, Joel B.; McVay, Jason C.; Kreitler, Jason R.; Hawbaker, Todd J.; Vaillant, Nicole; Lowe, Scott

2015-01-01

Increased sedimentation following wildland fire can negatively impact water supply and water quality. Understanding how changing fire frequency, extent, and location will affect watersheds and the ecosystem services they supply to communities is of great societal importance in the western USA and throughout the world. In this work we assess the utility of the InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs) Sediment Retention Model to accurately characterize erosion and sedimentation of burned watersheds. InVEST was developed by the Natural Capital Project at Stanford University (Tallis et al., 2014) and is a suite of GIS-based implementations of common process models, engineered for high-end computing to allow the faster simulation of larger landscapes and incorporation into decision-making. The InVEST Sediment Retention Model is based on common soil erosion models (e.g., USLE – Universal Soil Loss Equation) and determines which areas of the landscape contribute the greatest sediment loads to a hydrological network and conversely evaluate the ecosystem service of sediment retention on a watershed basis. In this study, we evaluate the accuracy and uncertainties for InVEST predictions of increased sedimentation after fire, using measured postfire sediment yields available for many watersheds throughout the western USA from an existing, published large database. We show that the model can be parameterized in a relatively simple fashion to predict post-fire sediment yield with accuracy. Our ultimate goal is to use the model to accurately predict variability in post-fire sediment yield at a watershed scale as a function of future wildfire conditions.

Critical Source Area Delineation: The representation of hydrology in effective erosion modeling.

Science.gov (United States)

Fowler, A.; Boll, J.; Brooks, E. S.; Boylan, R. D.

2017-12-01

Despite decades of conservation and millions of conservation dollars, nonpoint source sediment loading associated with agricultural disturbance continues to be a significant problem in many parts of the world. Local and national conservation organizations are interested in targeting critical source areas for control strategy implementation. Currently, conservation practices are selected and located based on the Revised Universal Soil Loss Equation (RUSLE) hillslope erosion modeling, and the National Resource Conservation Service will soon be transiting to the Watershed Erosion Predict Project (WEPP) model for the same purpose. We present an assessment of critical source areas targeted with RUSLE, WEPP and a regionally validated hydrology model, the Soil Moisture Routing (SMR) model, to compare the location of critical areas for sediment loading and the effectiveness of control strategies. The three models are compared for the Palouse dryland cropping region of the inland northwest, with un-calibrated analyses of the Kamiache watershed using publicly available soils, land-use and long-term simulated climate data. Critical source areas were mapped and the side-by-side comparison exposes the differences in the location and timing of runoff and erosion predictions. RUSLE results appear most sensitive to slope driving processes associated with infiltration excess. SMR captured saturation excess driven runoff events located at the toe slope position, while WEPP was able to capture both infiltration excess and saturation excess processes depending on soil type and management. A methodology is presented for down-scaling basin level screening to the hillslope management scale for local control strategies. Information on the location of runoff and erosion, driven by the runoff mechanism, is critical for effective treatment and conservation.

GIS-based evaluation and spatial distribution characteristics of land degradation in Bijiang watershed.

Science.gov (United States)

Zhao, Xiaoqing; Dai, Jinhua; Wang, Jianping

2013-01-01

Land degradation is one of the significant issues the human beings are confronted with, which has become a bottleneck of restricting the sustainable development of the regional society and economy. In order to ascertain the root causes contributed to the land degradation and characteristics of land degradation, Bijiang watershed, the most important Lead-Zinc mine area of Lanping county of Yunnan Province, was selected as the study area. One evaluation index system for land degradation that consists of 5 single factors(water-soil erosion intensity, geological disaster risk, cultivation intensity of arable land, pollution of heavy metals in soil and biodiversity deterioration) was established and 13 indicators were chosen, and the entropy method was adopted to assign weights to each single factor. By using the tools of Geographic Information System (GIS), the land degradation degree was evaluated and one spatial distribution map for land degradation was accomplished. In this study, the land of the whole watershed was divided into 4 types, including extremely-severe degradation area, severely-degraded area, moderately-degraded area and slightly-degraded area, and some solutions for ecological restoration and rehabilitation were also put forward in this study. The study results indicated that: (1) Water-soil erosion intension and pollution of heavy metals in soil have made greater contribution to the comprehensive land degradation in Bijiang watershed; (2) There is an apparent difference regarding land degradation degree in Bijiang watershed. The moderately-degraded area accounts for the most part in the region, which covers 79.66% of the whole watershed. The severely-degraded area accounts for 15.98% and the slightly-degraded regions and extremely severe degradation area accounts for 1.08% and 3.28% respectively; (3) There is an evident regularity of spatial distribution in land degradation in Bijiang watershed. The moderately-degraded areas mainly distribute in the

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

Science.gov (United States)

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.

Sediment delivery ratio in a small semi-arid watershed under conditions of low connectivity

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Julio Cesar Neves dos Santos

Full Text Available ABSTRACT The semi-arid region in the northeast of Brazil is characterised by rains of high intensity and short duration, with the processes of erosion being aggravated by an inappropriate land-use model. In this region, the lack of measured data for runoff and sediment yield increases the need to apply hydro-sedimentological models in estimating erosion, requiring knowledge of the actual sediment delivery ratio for the region. The aim of this study therefore, was to map soil erosion, making use of the Universal Soil Loss Equation (USLE, in the Iguatu Experimental Watershed (IEW. The mean annual sediment delivery ratio (SDR, and the SDR for individual events, was calculated from hydro-sedimentological measurements, contributing to an understanding of the processes of sediment propagation in the Brazilian semi-arid region, allowing identification of areas susceptible to water erosion. The IEW has an area of 16.74 km2 and is equipped with sensors for the continuous measurement of rainfall, flow and sediment yield. The mean annual SDR for the IEW was 0.37%. The SDR for individual rainfall events ranged from 0.08 to 1.67%, with an average of 0.68%. Among the main variables that influence the SDR for individual events is the magnitude of rainfall depth and antecedent soil moisture that can be better represented by the total antecedent precipitation of the previous 15 days. According to maps of soil loss, only 6.27% of the watershed presented losses beyond tolerable limits.

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)

Agroforestry practices, runoff, and nutrient loss: a paired watershed comparison.

Science.gov (United States)

Udawatta, Ranjith P; Krstansky, J John; Henderson, Gray S; Garrett, Harold E

2002-01-01

A paired watershed study consisting of agroforestry (trees plus grass buffer strips), contour strips (grass buffer strips), and control treatments with a corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] rotation was used to examine treatment effects on runoff, sediment, and nutrient losses. During the (1991-1997) calibration and subsequent three-year treatment periods, runoff was measured in 0.91- and 1.37-m H-flumes with bubbler flow meters. Composite samples were analyzed for sediment, total phosphorus (TP), total nitrogen (TN), nitrate, and ammonium. Calibration equations developed to predict runoff, sediment, and nutrients losses explained 66 to 97% of the variability between treatment watersheds. The contour strip and agroforestry treatments reduced runoff by 10 and 1% during the treatment period. In both treatments, most runoff reductions occurred in the second and third years after treatment establishment. The contour strip treatment reduced erosion by 19% in 1999, while erosion in the agroforestry treatment exceeded the predicted loss. Treatments reduced TP loss by 8 and 17% on contour strip and agroforestry watersheds. Treatments did not result in reductions in TN during the first two years of the treatment period. The contour strip and agroforestry treatments reduced TN loss by 21 and 20%, respectively, during a large precipitation event in the third year. During the third year of treatments, nitrate N loss was reduced 24 and 37% by contour strip and agroforestry treatments. Contour strip and agroforestry management practices effectively reduced nonpoint-source pollution in runoff from a corn-soybean rotation in the clay pan soils of northeastern Missouri.

Application of spatial Markov chains to the analysis of the temporal-spatial evolution of soil erosion.

Science.gov (United States)

Liu, Ruimin; Men, Cong; Wang, Xiujuan; Xu, Fei; Yu, Wenwen

Soil and water conservation in the Three Gorges Reservoir Area of China is important, and soil erosion is a significant issue. In the present study, spatial Markov chains were applied to explore the impacts of the regional context on soil erosion in the Xiangxi River watershed, and Thematic Mapper remote sensing data from 1999 and 2007 were employed. The results indicated that the observed changes in soil erosion were closely related to the soil erosion levels of the surrounding areas. When neighboring regions were not considered, the probability that moderate erosion transformed into slight and severe erosion was 0.8330 and 0.0049, respectively. However, when neighboring regions that displayed intensive erosion were considered, the probabilities were 0.2454 and 0.7513, respectively. Moreover, the different levels of soil erosion in neighboring regions played different roles in soil erosion. If the erosion levels in the neighboring region were lower, the probability of a high erosion class transferring to a lower level was relatively high. In contrast, if erosion levels in the neighboring region were higher, the probability was lower. The results of the present study provide important information for the planning and implementation of soil conservation measures in the study area.

Erosion of the Alberta badlands produces highly variable and elevated heavy metal concentrations in the Red Deer River, Alberta.

Science.gov (United States)

Kerr, Jason G; Cooke, Colin A

2017-10-15

Erosion is important in the transport of heavy metals from terrestrial to fluvial environments. In this study, we investigated riverine heavy metal (Cd, Cu, Hg and Pb) dynamics in the Red Deer River (RDR) watershed at sites upstream (n=2) and downstream (n=7) of the Alberta badlands, an area of naturally high erosion. At sites draining the badlands, total water column Cd, Cu, Hg and Pb concentrations frequently exceeded guidelines for the protection of freshwater biota. Furthermore, peak concentrations of total Cd (9.8μgL -1 ), Cu (212μgL -1 ), Hg (649ngL -1 ) and Pb (361μgL -1 ) were higher than, or comparable to, values reported for rivers and streams heavily impacted by anthropogenic activities. Total suspended solids (TSS) explained a large proportion (r 2 =0.34-0.83) of the variation in total metal concentrations in the RDR and tributaries and metal fluxes were dominated by the particulate fraction (60-98%). Suspended sediment concentrations (C sed ) and metal to aluminum ratios were generally not indicative of substantial sediment enrichment. Rather, the highly variable and elevated metal concentrations in the RDR watershed were a function of the high and variable suspended sediment fluxes which characterize the river system. While the impact of this on aquatic biota requires further investigation, we suggest erosion in the Alberta badlands may be contributing to Hg-based fish consumption advisories in the RDR. Importantly, this highlights a broader need for information on contaminant dynamics in watersheds subject to elevated rates of erosion. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Clinical Comparison of Outcomes of Early versus Delayed Carotid Artery Stenting for Symptomatic Cerebral Watershed Infarction due to Stenosis of the Proximal Internal Carotid Artery

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Huakun Liu

2016-01-01

Full Text Available The aim of this study was to compare the clinical outcomes of early versus delayed carotid artery stenting (CAS for symptomatic cerebral watershed infarction (sCWI patients due to stenosis of the proximal internal carotid artery. We retrospectively collected clinical data of those who underwent early or delayed CAS from March 2011 to April 2014. The time of early CAS and delayed CAS was within a week of symptom onset and after four weeks from symptom onset. Clinical data such as second stroke, the National Institutes of Health Stroke Scale (NHISS score, and modified Rankin Scale (mRS score and periprocedural complications were collected. The rate of second stroke in early CAS group is lower when compared to that of delayed CAS group. There was no significant difference regarding periprocedural complications in both groups. There was a significant difference regarding mean NHISS score 90 days after CAS in two groups. Early CAS group had a significant better good outcome (mRS score ≤ 2 than delayed CAS group. We suggest early CAS for sCWI due to severe proximal internal carotid artery stenosis as it provides lower rate of second stroke, comparable periprocedural complications, and better functional outcomes compared to that of delayed CAS.

Erosion and deposition in a field/forest system estimated using cesium-137 activity

International Nuclear Information System (INIS)

Lowrance, R.; McIntyre, S.; Lance, C.

1988-01-01

Soil erosion and deposition were estimated using Cs-137 activity within a 7.25-ha field/forest system in the southeastern coastal plain. Sol eroded from the field was deposited both in the riparian forest ecosystem and in downslope areas of the field. Total activity, depth to peak activity, and depth to zero activity increased downslope from field to stream. Erosion and deposition rates, estimated by changes in activity per unit area from a reference undisturbed forest site, showed that about twice as much total deposition had taken place as total erosion. Excess deposition was attributed to deposition from the upstream portions of the watershed. Erosion and deposition rates estimated with this method were about 63 and 256 Mg/ha/yr, respectively. Erosion and deposition rates estimated by two different calculation techniques were nearly identical. These rates were considerably higher than rates estimated in an earlier study. The rates may be overestimated because the differential rates of Cs-137 movement on clay particles were not considered. The riparian ecosystem acted as a very efficient sediment trap. 19 refs., 5 figs., 3 tabs

Mitigation of land degradation at Juana Watershed, Central Java

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I.B. Pramono

2014-10-01

Full Text Available Land degradation became more and more widespread, especially in areas with a dense population and dependence on agriculture is high enough. Land degradation can be approximated by the susceptibility of land to erosion. This study aims to identify existing land degradation in the Juana watershed, Central Java. The method used is the analysis of the typology of the watershed. This method is based on the interaction between landforms and land cover. The results showed that the degradation of land in the watershed very heavy scattered in the upstream areas in the territory of the Kudus and Pati regency. While severe land degradation are also scattered in Kudus, Pati, and Blora regency. Almost all of these degraded areas are used for dry land farming. By knowing the rate of spread of land degradation, the authority having jurisdiction in this district offices on issues related to land degradation can plan the actions necessary to resolve or mitigate land degradation in each region so that a major disaster will not happen or the impact can be minimized

Gastroesophageal Reflux Disease and Tooth Erosion

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Sarbin Ranjitkar

2012-01-01

Full Text Available The increasing prevalence of gastroesophageal reflux disease (GERD in children and adults, and of “silent refluxers” in particular, increases the responsibility of dentists to be alert to this potentially severe condition when observing unexplained instances of tooth erosion. Although gastroesophageal reflux is a normal physiologic occurrence, excessive gastric and duodenal regurgitation combined with a decrease in normal protective mechanisms, including an adequate production of saliva, may result in many esophageal and extraesophageal adverse conditions. Sleep-related GERD is particularly insidious as the supine position enhances the proximal migration of gastric contents, and normal saliva production is much reduced. Gastric acid will displace saliva easily from tooth surfaces, and proteolytic pepsin will remove protective dental pellicle. Though increasing evidence of associations between GERD and tooth erosion has been shown in both animal and human studies, relatively few clinical studies have been carried out under controlled trial conditions. Suspicion of an endogenous source of acid being associated with observed tooth erosion requires medical referral and management of the patient as the primary method for its prevention and control.

Geospatial techniques for developing a sampling frame of watersheds across a region

Science.gov (United States)

Gresswell, Robert E.; Bateman, Douglas S.; Lienkaemper, George; Guy, T.J.

2004-01-01

Current land-management decisions that affect the persistence of native salmonids are often influenced by studies of individual sites that are selected based on judgment and convenience. Although this approach is useful for some purposes, extrapolating results to areas that were not sampled is statistically inappropriate because the sampling design is usually biased. Therefore, in recent investigations of coastal cutthroat trout (Oncorhynchus clarki clarki) located above natural barriers to anadromous salmonids, we used a methodology for extending the statistical scope of inference. The purpose of this paper is to apply geospatial tools to identify a population of watersheds and develop a probability-based sampling design for coastal cutthroat trout in western Oregon, USA. The population of mid-size watersheds (500-5800 ha) west of the Cascade Range divide was derived from watershed delineations based on digital elevation models. Because a database with locations of isolated populations of coastal cutthroat trout did not exist, a sampling frame of isolated watersheds containing cutthroat trout had to be developed. After the sampling frame of watersheds was established, isolated watersheds with coastal cutthroat trout were stratified by ecoregion and erosion potential based on dominant bedrock lithology (i.e., sedimentary and igneous). A stratified random sample of 60 watersheds was selected with proportional allocation in each stratum. By comparing watershed drainage areas of streams in the general population to those in the sampling frame and the resulting sample (n = 60), we were able to evaluate the how representative the subset of watersheds was in relation to the population of watersheds. Geospatial tools provided a relatively inexpensive means to generate the information necessary to develop a statistically robust, probability-based sampling design.

Prescribed Burning and Erosion Potential in Mixed Hardwood Forests of Southern Illinois

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Gurbir Singh

2017-04-01

Full Text Available Prescribed fire has several benefits for managing forest ecosystems including reduction of fuel loading and invasive species and enhanced regeneration of desirable tree species. Along with these benefits there are some limitations like nutrient and sediment loss which have not been studied extensively in mixed hardwood forests. The objective of our research was to quantify the amount of sediment movement occurring on a watershed scale due to prescribed fire in a southern Illinois mixed hardwood ecosystem. The research site was located at Trail of Tears State Forest in western Union county, IL, USA and included five watershed pairs. One watershed in each pair was randomly assigned the prescribed burn treatment and the other remained as control (i.e., unburned. The prescribed burn treatment significantly reduced the litter depth with 12.6%–31.5% litter remaining in the prescribed burn treatment watersheds. When data were combined across all watersheds, no significant differences were obtained between burn treatment and control watershed for total suspended solids and sediment concentrations or loads. The annual sediment losses varied from 1.41 to 90.54 kg·ha−1·year−1 in the four prescribed burn watersheds and 0.81 to 2.54 kg·ha−1·year−1 in the four control watersheds. Prescribed burn watershed 7 showed an average soil sediment loss of 4.2 mm, whereas control watershed 8 showed an average accumulation of sediments (9.9 mm, possibly due to steeper slopes. Prescribed burning did not cause a significant increase in soil erosion and sediment loss and can be considered acceptable in managing mixed hardwood forests of Ozark uplands and the Shawnee Hills physiographic regions of southern Illinois.

Comparison of 137Cs fallout redistribution analysis and conventional erosion-prediction models (WEPP, USLE)

International Nuclear Information System (INIS)

Sparovek, G.; Bacchi, O.O.S.; Ranieri, S.B.L.; Schnug, E.; De-Maria, I.C.

2002-01-01

Soil erosion is the most important component of the degradation of tropical agroecosystems. The rates of erosion should be considered in land evaluation and conservation planning assessment. The methods available for erosion prediction are not sufficiently well calibrated or validated for tropical soils, climates and crops. Thus, differences in estimated soil-erosion values may be expected, even if considering a single set of input data. Three methods for the estimation of soil erosion (USLE, WEPP, and 137 Cs) were applied to a watershed cultivated with sugarcane in southeastern Brazil. The absolute erosion-rate values and differences in the spatial distribution were evaluated. The overall results suggest important differences in the estimates obtained by the three methods. The differences occurred both in mean values and in geographic locations. The relative mean values for soil loss were USLE>> 137 Cs>WEPP and for standard deviations were USLE>WEPP> 137 Cs, indicating that USLE predicted the highest erosion values spread out over the widest range. The poor geographical coincidence of the results is evidence that values resulting from non-calibrated erosion methods should be considered only as qualitative indications. The method selection should consider overall site variability in relation to factors to which the methods are known to be sensitive. (author)

Land Capability Analysis on Farming System at Serang Sub-Watershed Kedung Ombo Reservoir Catchment Area

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Jaka Suyana

2014-07-01

Full Text Available Soil conservation in principle is using the land according to its capability and keep them from damage. This study aims at assessing the land capability classes of farming systems at Serang sub-watershed and evaluate their usages. The results showed that the land capability dominated by Class II (12,096.90 ha, 40.6%, followed by Class III (11,598.92 ha, 38.9%, Class IV (2,879.11 ha, 9.7%, Class I (1,333.14 ha, 4.5%, Class VIII (712.57 ha, 2.4%, Class VII (684.97 ha, 2.3% and Class VI (512.84 ha, 1.7%. The main resistance factors are slope and soil deepth for class II; slope, soil deepth, drainage and erosion for class III; slope and erosion for class IV; and slope for class VIII, VII and VI. The results showed that 94% farm lands at Serang sub-watershed was suitable to its land capability and only 6.0% were not suitable.

Measuring the Erosion of River Channel Widths Impacted by Watershed Urbanization Using Historic Aerial Photographs and Modern Surveys

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Galster, J. C.; Pazzaglia, F. J.; Germanoski, D.

2007-12-01

Land use in a watershed exerts a strong influence on trunk channel form and process. Land use changes act over human time scales which is short enough to measure their effects directly using historic aerial photographs. We show that high-resolution topographic surveys comparing channel form for paired watersheds in the Lehigh Valley, PA are indistinguishable, but have channel widths that have changed dramatically in the past five decades. The two watersheds, Little Lehigh Creek and Sacony Creek, are similar in all respects except they have different amount of urban land use. Aerial photographs of the urbanized Little Lehigh Creek show that a majority of the measured widths (67 of 85) were statistically wider in 1999 than in 1947. In contrast, the measured widths from the agricultural Sacony Creek are more evenly distributed among those that widened (18), narrowed (28), and those that were statistically unchanged (6) from 1946 to 1999. From 1946 to 1999 the only section of Sacony creek that widened was that reach downstream of the only sizable urban area in the watershed. The current land use in Sacony Creek watershed resembles that of 1946, while the Little Lehigh Creek watershed has more than tripled its urban area. These data suggest that the increase in urban areas that subsequently increases peak discharges is the mechanism behind the widening that occurred in the Little Lehigh Creek. These wider channels can affect water quality, aquatic habitat, suspended sediment loads, and river aesthetics.

Evaluation of post fire changes in soil properties and influence on the hydrological and erosive dynamics in a Mediterranean watershed

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Sanz, Inés; Aguilar, Cristina; Millares, Agustín

2013-04-01

In the last fifty years, forest fires and changes in land use and management practices have had a significant influenceon the evolution of soil loss processes in the Mediterranean area. Forest fires have immediate effects in hydrological processes mainly due to sudden changes in soil properties and vegetation cover. After a fire there is an increase in runoff processes and peak flows and thus in the amount and composition of the sediments produced. Silting in dams downstream is often reported so the description of the post-fire hydrological processes is crucial in order to optimize decision making. This study analyzes a micro-watershed of 25 ha in the south of Spain that suffered a fire in October 2010 burning around a 2 km2 area. As the erosive processes in this area are directly related to concentrated overland flow, an indirect assessment of soil loss is presented in this work based on evaluating changes in runoff in Mediterranean post-fire situations. For this, the study is divided into two main parts. Firstly, changes in soil properties and vegetation cover are evaluated. Secondly, the effects of these changes in the hydrological and erosive dynamics are assessed.The watershed had been monitored in previous studies so soil properties and the vegetation cover before the fire took place were already characterized. Besides, the hydrological response was also available through an already calibrated and validated physically-based distributed hydrological model. For the evaluation of soil properties, field measurement campaigns were designed. Philip Dunne's tests for the determination of saturated hydraulic conductivity, as well as moisture content and bulk density measurements were carried out in both unaltered and burned soil samples. Changes in the vegetation cover fraction were assessed through desktop analysis of Landsat-TM5 platform satellite images as well as through visual inspection in the field campaigns. The analysis of the hydraulic conductivity revealed

Simulação da variabilidade espacial da erosão hídrica em uma sub-bacia hidrográfica de Latossolos no sul de Minas Gerais Simulation of water erosion spatial variability in a watershed representative of oxisols in southern Minas Gerais State

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Antônio Marciano da Silva

2008-10-01

Full Text Available A simulação da distribuição espacial da erosão do solo consiste em uma ferramenta poderosa para o planejamento conservacionista em bacias hidrográficas, sendo uma importante aplicação da Equação Universal de Perdas de Solo (EUPS associada a princípios de interpolação espacial, principalmente a geoestatística. Este trabalho objetivou simular a distribuição espacial da erosão hídrica numa sub-bacia hidrográfica da região do Alto Rio Grande (MG, aplicando ferramentas geoestatísticas para distribuição espacial e mapeamento. Diferentes cenários de uso do solo foram analisados. A erosão foi estimada com base na EUPS aplicada a células, considerando as unidades pedológicas e diferentes usos em cada célula. O fator topográfico (LS das células foi obtido com base no Modelo Digital de Elevação da sub-bacia, identificando comprimento e direção principal do escoamento. A erosividade média anual da região é de 8.030 MJ mm ha-1 h-1 ano-1, e a erodibilidade dos solos foi extraída da literatura. A EUPS foi aplicada a cada célula, levando-se em conta a situação atual do solo, áreas degradadas plantadas com eucalipto, pastagem plantada e plantio convencional de milho, considerando a ocupação de toda a sub-bacia hidrográfica. Na situação atual, a sub-bacia apresenta taxas de erosão inferiores aos limites de tolerância para os respectivos solos, com exceção das áreas degradadas ocupadas por eucalipto e pastagem em Cambissolo. No entanto, em todas as situações analisadas, seu lado leste apresentou as maiores perdas de solo, especialmente para os cenários de eucalipto nas condições atuais e plantio convencional de milho em Cambissolo e Latossolo Vermelho-Amarelo, sendo necessária a aplicação de técnicas conservacionistas.Simulation of water erosion spatial distribution is an important tool for soil conservation planning in watersheds, being an important application of the Universal Soil Loss Equation (USLE

Bank-derived material dominates fluvial sediment in a suburban Chesapeake Bay watershed

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Cashman, M. J.; Gellis, A.; Gorman-Sanisaca, L.; Noe, G. B.; Cogliandro, V.; Baker, A.

2017-12-01

Excess fine sediment is a leading cause of ecological degradation within the Chesapeake Bay watershed. The Piedmont physiographic province, which includes parts of the Washington, D.C. metro area, has the highest sediment yields in the Chesapeake Bay. In order to effectively employ sediment mitigation measures, it is necessary to identify and quantify the contributions of sediments sources within rapidly urbanizing areas in the Piedmont. This sediment fingerprinting study examines the inputs of various sediment sources to Upper Difficult Run (14.2 km2; 22.6% impervious surface), an urbanized watershed in Fairfax County, Virginia. A source sediment library was constructed from collections of stream bank material, forest soils, and road dust from across the watershed. Target fluvial sediments were collected from fine channel margin deposits and from suspended sediment using an autosampler during 16 storm events from 2008 - 2012. Apportionment of the target samples to the source sediments was performed using Sed_SAT, a publically available toolkit for sediment fingerprinting. Bed sediment was found to be dominated by stream bank sources (mean: 96%), with minor contributions from forest (4%) and no detectable contribution from roads (0%). Suspended fine sediments were also found to predominantly originate from stream bank sources (SSC-weighted mean: 91%), with minor contributions from roads (8%), and negligible contributions from forests (1%). Stream bank sources dominated at all discharges, with the greatest contributions from overland sources found only at low discharges. On the rising limb of the hydrograph and at peak flow, sediment concentrations increased due to increasing contributions of bank material rather than surface erosion caused by overland flow. Results demonstrate that stream bank erosion is responsible for the vast majority of fine sediment occurring in this suburban basin of the Chesapeake Bay watershed. This is likely a consequence of storm

Mountain erosion over 10 yr, 10 k.y., and 10 m.y. time scales

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James W. Kirchner; Robert C. Finkel; Clifford S. Riebe; Darryl E. Granger; James L. Clayton; John G. King; Walter F. Megahan

2001-01-01

We used cosmogenic 10Be to measure erosion rates over 10 k.y. time scales at 32 Idaho mountain catchments, ranging from small experimental watersheds (0.2 km2) to large river basins (35 000 km2). These long-term sediment yields are, on average, 17 times higher than stream sediment fluxes measured over...

Science You Can Use Bulletin: From watersheds to the web: Online tools for modeling forest soil erosion

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Sue Miller; Bill Elliot; Pete Robichaud; Randy Foltz; Dennis Flanagan; Erin Brooks

2014-01-01

Forest erosion can lead to topsoil loss, and also to damaging deposits of sediment in aquatic ecosystems. For this reason, forest managers must be able to estimate the erosion potential of both planned management activities and catastrophic events, in order to decide where to use limited funds to focus erosion control efforts. To meet this need, scientists from RMRS (...

Combined impacts of land use and soil property changes on soil erosion in a mollisol area under long-term agricultural development.

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Ouyang, Wei; Wu, Yuyang; Hao, Zengchao; Zhang, Qi; Bu, Qingwei; Gao, Xiang

2018-02-01

Soil erosion exhibits special characteristics in the process of agricultural development. Understanding the combined impacts of land use and soil property changes on soil erosion, especially in the area under long-term agricultural cultivations, is vital to watershed agricultural and soil management. This study investigated the temporal-spatial patterns of the soil erosion based on a modified version of Universal Soil Loss Equation (USLE) and conducted a soil erosion contribution analysis. The land use data were interpreted from Landsat series images, and soil properties were obtained from field sampling, laboratory tests and SPAW (Soil-Plant-Atmosphere-Water) model calculations. Over a long period of agricultural development, the average erosion modulus decreased from 187.7tkm -2 a -1 in 1979 to 158.4tkm -2 a -1 in 2014. The land use types were transformed mainly in the reclamation of paddy fields and the shrinking of wetlands on a large scale. Most of the soils were converted to loam from silty or clay loam and the saturated hydraulic conductivity (K s ) of most soil types decreased by 1.11% to 43.6%. The rapidly increasing area of 49.8km 2 of paddy fields together with the moderate decrease of 14.0km 2 of forests, as well as K s values explained 87.4% of the total variance in soil erosion. Although changes in soil physical and water characteristics indicated that soil erosion loads should have become higher, the upsurge in paddy fields played an important role in mitigating soil erosion in this study area. These results demonstrated that land use changes had more significant impacts than soil property changes on soil erosion. This study suggested that rational measures should be taken to extend paddy fields and control the dry land farming. These findings will benefit watershed agricultural targeting and management. Copyright © 2017 Elsevier B.V. All rights reserved.

Freeze-thaw processes and intense winter rainfall: The one-two punch for high streambank legacy sediment and nutrient loads from Mid-Atlantic watersheds

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Inamdar, S. P.; Johnson, E. R.; Rowland, R. D.; Walter, R. C.; Merritts, D.

2017-12-01

Historic and contemporary anthropogenic soil erosion combined with early-American milldams resulted in large deposits of legacy sediments in the valley bottoms of Piedmont watersheds of the eastern US. Breaching of milldams subsequently yielded highly incised streams with exposed vertical streambanks that are vulnerable to erosion. Streambank erosion is attributed to fluvial scouring, freeze-thaw processes and mass wasting. While streambanks represent a large reservoir of fine sediments and nutrients, there is considerable uncertainty about the contribution of these sources to watershed nonpoint source pollution. Using high-frequency hydrologic, sediment, and turbidity data we show that freeze-thaw events followed by intense winter rainstorms can export unusually high concentrations of suspended sediment and particulate nutrients from watersheds. Data from a 12 ha forested, Piedmont, stream following an intense rain event (54 mm) on February 2016 yielded suspended sediment and particulate nutrient (organic carbon and nitrogen) concentrations and exports that exceeded those from tropical storms Irene, Lee, and Sandy that had much greater rainfall and discharge amounts, but which occurred later in the year. A similar response was also observed with regards to turbidity data for USGS stream monitoring locations at Brandywine Creek (813 km2) and White Clay Creek (153 km2). We hypothesize that much of the sediment export associated with winter storms is likely due to erosion of streambank sediments and was driven by the coupled occurrence of freeze-thaw conditions and intense rainfall events. We propose that freeze-thaw erosion represents an important and underappreciated mechanism in streams that "recharges" the sediment supply, which then is available for flushing by moderate to large storms. Future climate projections indicate increased intensification of storm events and increased variability of winter temperatures. Freeze-thaw cycles coupled with winter rain events

Creating an Erosion Vulnerability Map for the Columbia River Basin to Determine Reservoir Susceptibility to Sedimentation Before and After Wildfires

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Ren, J.; Robichaud, P. J. L.; Adam, J. C.

2017-12-01

Sedimentation is important issue to most rivers and reservoirs especially in watersheds with extensive agricultural or wildfire activity. These human and natural induced disturbances have the potential to increase runoff-induced erosion and sediment load to rivers; downstream sedimentation can decrease the life expectancy of reservoir and consequently the dam. This is particularly critical in snowmelt-dominant regions because, as rising temperatures reduce snowpack as a natural reservoir, humans will become more reliant on reservoir storage. In the Northwest U.S., the Columbia River Basin (CRB) has more than 60 dams, which were built for irrigation, hydropower, and flood control, all of which are affected by sediment to varying degrees. Determining what dams are most likely to be affected by sedimentation caused by post-fire erosion is important for future management of reservoirs, especially as climate change is anticipated to exacerbate wildfire and its impacts. The objective of this study is to create a sedimentation vulnerability map for reservoirs in the CRB. There are four attributes of a watershed that determine erosion potential; soil type, topography, vegetation (such as forests, shrubs, and grasslands), and precipitation (although precipitation was excluded in this analysis). In this study, a rating system was developed on a scale of 0-90 (with 90 having the greatest erosion potential). The different layers in a Graphical Information System were combined to create an erosion vulnerability map. Results suggest that areas with agriculture have more erosion without a wildfire but that forested areas are most vulnerable to erosion rates following a fire, particularly a high severity fire. Sedimentation in dams is a growing problem that needs to be addressed especially with the likely reduction in snowpack, this vulnerability map will help determine which reservoirs in the CRB are prone to high sedimentation. This information can inform managers where post

Budgeting suspended sediment fluxes in tropical monsoonal watersheds with limited data: the Lake Tana basin

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Zimale Fasikaw A.

2018-03-01

Full Text Available Soil erosion decreases soil fertility of the uplands and causes siltation of lakes and reservoirs; the lakes and reservoirs in tropical monsoonal African highlands are especially affected by sedimentation. Efforts in reducing loads by designing management practices are hampered by lack of quantitative data on the relationship of erosion in the watersheds and sediment accumulation on flood plains, lakes and reservoirs. The objective of this study is to develop a prototype quantitative method for estimating sediment budget for tropical monsoon lakes with limited observational data. Four watersheds in the Lake Tana basin were selected for this study. The Parameter Efficient Distributed (PED model that has shown to perform well in the Ethiopian highlands is used to overcome the data limitations and recreate the missing sediment fluxes. PED model parameters are calibrated using daily discharge data and the occasionally collected sediment concentration when establishing the sediment rating curves for the major rivers. The calibrated model parameters are then used to predict the sediment budget for the 1994-2009 period. Sediment retained in the lake is determined from two bathymetric surveys taken 20 years apart whereas the sediment leaving the lake is calculated based on measured discharge and observed sediment concentrations. Results show that annually on average 34 t/ha/year of sediment is removed from the gauged part of the Lake Tana watersheds. Depending on the up-scaling method from the gauged to the ungauged part, 21 to 32 t/ha/year (equivalent to 24-38 Mt/year is transported from the upland watersheds of which 46% to 65% is retained in the flood plains and 93% to 96% is trapped on the flood plains and in the lake. Thus, only 4-7% of all sediment produced in the watersheds leaves the Lake Tana Basin.

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

representation and spatial routing and proper accounting of sediment detachment/deposition from cumulative wind or water events. Future planned model additions will include the ability to also account for tillage erosion effects and ephemeral gully erosion. Modules from this project may also be utilized in larger watershed models that would be applied at progressively larger scales. One of the advantages of the model integration is that it will allow future erosion process descriptions, such as combined effects of wind and water forces on soil detachment (i.e., wind-driven rain detachment).

Determining Sediment Sources in the Anacostia River Watershed

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Devereux, O. H.; Needelman, B. A.; Prestegaard, K. L.; Gellis, A. C.; Ritchie, J. C.

2005-12-01

Suspended sediment is a water-quality problem in the Chesapeake Bay. This project is designed to identify sediment sources in an urban watershed, the Northeast Branch of the Anacostia River (in Washington, D.C. and Maryland - drainage area = 188.5 km2), which delivers sediment directly to the Bay. This watershed spans two physiographic regions - the Piedmont and Coastal Plain. Bank sediment and suspended-sediment deposits were characterized using the following techniques: radionuclide (Cs-137) analysis by gamma ray spectrometry, trace-element analysis by ICP-MS, clay mineralogy by XRD, and particle-size analysis by use of a laser particle-size analyzer. Sampling of bank and suspended sediment was designed to: a) characterize tributary inputs from both Piedmont and Coastal Plain sources, and b) differentiate tributary inputs from bank erosion along the main stem of the Northeast Branch. Thirteen sample sites were chosen that represent tributary source areas of each physiographic region and the main stem where mixing occurs. Surface samples of the banks were compared to overbank deposits from a ten year storm (a proxy for the suspended sediments). Fingerprint components are selected from these data. Cesium-137 concentrations were analyzed for bank and overbank deposits for each physiographic region. No clear differences were seen between the two physiographic regions. Significant differences were observed between upland tributaries and the main stem of the Anacostia River. The average activity of Cs-137 for the tributaries was 5.4 bq/kg and the average for the main stem was 1.1 bq/kg. This suggests that there is significant erosion and storage of sediment in the tributaries. The low activity from Cs-137 in the main stem suggests a lack of storage of sediment along the main stem of the river. For the trace-element data, we focused on elements that showed significant variation among the sites. For the bank sediment, these elements include: Sr, V, Y, Ce, and Nd. For the

Climate change impacts in Zhuoshui watershed, Taiwan

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Chao, Yi-Chiung; Liu, Pei-Ling; Cheng, Chao-Tzuen; Li, Hsin-Chi; Wu, Tingyeh; Chen, Wei-Bo; Shih, Hung-Ju

2017-04-01

There are 5.3 typhoons hit Taiwan per year on average in last decade. Typhoon Morakot in 2009, the most severe typhoon, causes huge damage in Taiwan, including 677 casualty and roughly NT 110 billion (3.3 billion USD) in economic loss. Some researches documented that typhoon frequency will decrease but increase in intensity in western North Pacific region. It is usually preferred to use high resolution dynamical model to get better projection of extreme events; because coarse resolution models cannot simulate intense extreme events. Under that consideration, dynamical downscaling climate data was chosen to describe typhoon satisfactorily. One of the aims for Taiwan Climate Change Projection and Information Platform (TCCIP) is to demonstrate the linkage between climate change data and watershed impact models. The purpose is to understand relative disasters induced by extreme rainfall (typhoons) under climate change in watersheds including landslides, debris flows, channel erosion and deposition, floods, and economic loss. The study applied dynamic downscaling approach to release climate change projected typhoon events under RCP 8.5, the worst-case scenario. The Transient Rainfall Infiltration and Grid-Based Regional Slope-Stability (TRIGRS) and FLO-2D models, then, were used to simulate hillslope disaster impacts in the upstream of Zhuoshui River. CCHE1D model was used to elevate the sediment erosion or deposition in channel. FVCOM model was used to asses a flood impact in urban area in the downstream. Finally, whole potential loss associate with these typhoon events was evaluated by the Taiwan Typhoon Loss Assessment System (TLAS) under climate change scenario. Results showed that the total loss will increase roughly by NT 49.7 billion (1.6 billion USD) in future in Zhuoshui watershed in Taiwan. The results of this research could help to understand future impact; however model bias still exists. Because typhoon track is a critical factor to consider regional

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.

Quantification of soil loss in various lithological areas of the western Middle Atlas Central: application to the Ras-Elma, Tamelalet and Sebab watershed (Tigrigra watershed, Morocco)

Science.gov (United States)

Achiban, Hassan; Taous, Ali; El-Khantoury, Ismail; El Mderssa, Mohamed; Amechrouq, Ali

2018-05-01

The present study proposes to evaluate the extent of erosion according to the lithology in three sub-watersheds (Ras Elma, Sebab and Tamelalet) belonging to the Tigrigra basin and evolving in humid climatic context. The methodology adopts the revised universal soil loss equation (RUSLE). The results obtained make it possible to establish erosion class maps via GIS. A clear spatial difference in soil loss is observed, between the three sub-basins and in proportion to the lithology: on average 42.15 t/ha/year on Paleozoic schistose soils, against 17.06 t/ha/year on carbonate substrates Mesozoic and 8.46 t/ha/year on quaternary basalts. Correlations between soil loss and RUSLE factors are established. Soil infiltration regimes on different substrates are studied.

Ponds' water balance and runoff of endorheic watersheds in the Sahel

Science.gov (United States)

Gal, Laetitia; Grippa, Manuela; Kergoat, Laurent; Hiernaux, Pierre; Mougin, Eric; Peugeot, Christophe

2015-04-01

The Sahel has been characterized by a severe rainfall deficit since the mid-twentieth century, with extreme droughts in the early seventies and again in the early eighties. These droughts have strongly impacted ecosystems, water availability, fodder resources, and populations living in these areas. However, an increase of surface runoff has been observed during the same period, such as higher "summer discharge" of Sahelian's rivers generating local floods, and a general increase in pond's surface in pastoral areas of central and northern Sahel. This behavior, less rain but more surface runoff is generally referred to as the "Sahelian paradox". Various hypotheses have been put forward to explain this paradoxical situation. The leading role of increase in cropped areas, often cited for cultivated Sahel, does not hold for pastoral areas in central and northern Sahel. Processes such as degradation of vegetation subsequent to the most severe drought events, soils erosion and runoff concentration on shallow soils, which generate most of the water ending up in ponds, seem to play an important role. This still needs to be fully understood and quantified. Our study focuses on a model-based approach to better understand the hydrological changes that affected the Agoufou watershed (Gourma, Mali), typical of the central, non-cultivated Sahel. Like most of the Sahelian basins, the Agoufou watershed is ungauged. Therefore we used indirect data to provide the information required to validate a rainfall-runoff model approach. The pond volume was calculated by combining in-situ water level measurements with pond's surface estimations derived by remote sensing. Using the pond's water balance equation, the variations of pond volume combined to estimates of open water bodies' evaporation and infiltration determined an estimation for the runoff supplying the pond. This estimation highlights a spectacular runoff increase over the last sixty years on the Agoufou watershed. The runoff

Redistribution of cesium-137 due to erosional processes in a Wisconsin watershed

International Nuclear Information System (INIS)

McHenry, J.R.; Ritchie, J.C.; Bubenzer, G.D.

1978-01-01

The distribution of fallout 137 Cs was studied in a small agricultural watershed in Shawano County, Wis. The watershed drains into White Clay Lake, a small, shallow glacial outwash lake. Soil samples were collected in 1974 and 1975 from wooded, pastured, and cultivated sites on the watershed. In the noncultivated areas 137 Cs was concentrated largely in the surface 5 cm of the soil pedons, but in the cultivated areas it was distributed throughout the plow layer. The amount of 137 Cs found in the cultivated areas was less per unit area than that found in the noncultivated areas. The amounts of 137 Cs found in the soil pedons in the cultivated areas were correlated with small changes in elevation. Thus, although the total content of 137 Cs for a given field indicated an overall loss, small changes in topography within fields have resulted in areas of excessive losses (erosion) and of accumulations

Land use change for flood protection: A prospective study for the restoration of the river Jelašnica watershed

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Ristić Ratko

2011-01-01

Full Text Available Serbia’s hilly-mountainous regions are extremely vulnerable to flooding as a consequence of their natural characteristics and human impacts. Land mismanagement influences the development of erosion processes, and causes soil degradation that significantly reduces the land’s capacity to infiltrate and retain rainwater. Inappropriate land use as well as development activities replace permeable with impervious surfaces in the watershed. This leads to more rapid runoff generation and the more frequent appearance of torrential floods and bed-load deposits on downstream sections. Environmental degradation creates economicsocial problems within local societies which is often followed by depopulation. Restoring watersheds to their optimal hydrologic state would reduce flood discharge and by increasing groundwater recharge would increase both low-flow and average discharges in springs and streams. Best management practices could be developed through the application of specific combinations of biotechnical, technical and administrative measures, and by using the concept of ″natural reservoirs″. The design of such practices is explored through a case study of the watershed of the river Jelašnica, southeastern Serbia. Realization of these planned restoration works should help decrease the annual yields of erosive material by 44.1% and the specific annual transport of sediment through hydrographic network by 43.6%. Representative value of the coefficient of erosion will be reduced from Z=0.555 to Z=0.379. The value of maximal discharge Qmax-AMCIII (1%=54.17 m3•s-1, before restoration, is decreased to Qmax-AMCIII (1%=41.22 m3•s-1 after restoration, indicating the improvement of hydrological conditions, as a direct consequence of land use changes. Administrative measures are applied through ″Plans for announcement of erosive regions and protection from torrential floods in the territory of Leskovac municipality″.

RAINFALL CHARACTERIZATION AND SEDIMENTOLOGICAL RESPONSES OF WATERSHEDS WITH DIFFERENT LAND USES TO PRECIPITATION IN THE SEMIARID REGION OF BRAZIL

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JACQUES CARVALHO RIBEIRO FILHO

2017-01-01

Full Text Available The objective of this work was to evaluated the precipitation characteristics (depth, I30 and erosivity and their effects on sediment production in three watersheds under different managements of land use 35 - year regenerating Caatinga (RC, thinned Caatinga (TC, which underwent thinning of trees with diameter smaller than 10 cm; and deforested Caatinga (followed by burning and pasture (DC. The experimente was conducted in the central, tropical semiarid region of the State of Ceará, Brazil. The precipitation events, surface runoff and sediment production were monitored from 2010 to 2015. The precipitation characteristics were subjected to Pearson's correlation at 1 and 5% of significance and the events that produced sediments in each watershed were hierarchically grouped by hierarchical cluster analysis technique. Two hundred precipitation events were recorded, with 23 (RC, 18 (TC and 43 (DC events producing sediments. The use of thinning (TC decreased the sediment production by 53.5%, while the deforestation, burn and pasture cultivation (DC increased soil losses by 14%, compared with the RC. The sediment production was greatly correlated with the I30 in the three watersheds, denoting the erosion process great dependence on the precipitation intensity.

Using an integrated method to estimate watershed sediment yield during heavy rain period: a case study in Hualien County, Taiwan

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S. M. Hsu

2012-06-01

Full Text Available A comprehensive approach estimating sediment yield from a watershed is needed to develop better measures for mitigating sediment disasters and assessing downstream impacts. In the present study, an attempt has been made to develop an integrated method, considering sediment supplies associated with soil erosion, shallow landslide and debris flow to estimate sediment yield from a debris-flow-prone watershed on a storm event basis. The integrated method is based on the HSPF and TRIGRS models for predicting soil erosion and shallow landslide sediment yield, and the FLO-2D model for calculating debris flow sediment yield. The proposed method was applied to potential debris-flow watersheds located in the Sioulin Township of Hualien County. The available data such as hourly rainfall data, historical streamflow and sediment records as well as event-based landslide inventory maps have been used for model calibration and validation. Results for simulating sediment yield have been confirmed by comparisons of observed data from several typhoon events. The verified method employed a 24-h design hyetograph with the 100-yr return period to simulate sediment yield within the study area. The results revealed that the influence of shallow landslides on sediment supply as compared with soil erosion was significant. The estimate of landslide transport capacity into a main channel indicated the sediment delivery ratio on a typhoon event basis was approximately 38.4%. In addition, a comparison of sediment yields computed from occurrence and non-occurrence of debris flow scenarios showed that the sediment yield from an occurrence condition was found to be increasing at about 14.2 times more than estimated under a non-occurrence condition. This implied watershed sediment hazard induced by debris flow may cause severe consequences.

Hydrologic Drivers of Soil Organic Carbon Erosion and Burial: Insights from a Spatially-explicit Model of a Degraded Landscape at the Calhoun Critical Zone Observatory

Science.gov (United States)

Dialynas, Y. G.; Bras, R. L.; Richter, D. D., Jr.

2017-12-01

Soil erosion and burial of organic material may constitute a substantial sink of atmospheric CO2. Attempts to quantify impacts of soil erosion on the soil-atmosphere C exchange are limited by difficulties in accounting for the fate of eroded soil organic carbon (SOC), a key factor in estimating of the net effect of erosion on the C cycle. Processes that transport SOC are still inadequately represented in terrestrial carbon (C) cycle models. This study investigates hydrologic controls on SOC redistribution across the landscape focusing on dynamic feedbacks between watershed hydrology, soil erosional processes, and SOC burial. We use tRIBS-ECO (Triangulated Irregular Network-based Real-time Integrated Basin Simulator-Erosion and Carbon Oxidation), a spatially-explicit model of SOC dynamics coupled with a physically-based hydro-geomorphic model. tRIBS-ECO systematically accounts for the fate of eroded SOC across the watershed: Rainsplash erosion and sheet erosion redistribute SOC from upland sites to depositional environments, altering depth-dependent soil biogeochemical properties in diverse soil profiles. Eroded organic material is transferred with sediment and can be partially oxidized upon transport, or preserved from decomposition by burial. The model was applied in the Calhoun Critical Zone Observatory (CZO), a site that is recovering from some of the most serious agricultural erosion in North America. Soil biogeochemical characteristics at multiple soil horizons were used to initialize the model and test performance. Remotely sensed soil moisture data (NASA SMAP) were used for model calibration. Results show significant rates of hydrologically-induced burial of SOC at the Calhoun CZO. We find that organic material at upland eroding soil profiles is largely mobilized by rainsplash erosion. Sheet erosion mainly drives C transport in lower elevation clayey soils. While SOC erosion and deposition rates declined with recent reforestation at the study site, the

Integrating biophysical and socioeconomic information for prioritizing watersheds in a Kashmir Himalayan lake: a remote sensing and GIS approach.

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Badar, Bazigha; Romshoo, Shakil A; Khan, M A

2013-08-01

Dal Lake, a cradle of Kashmiri civilization has strong linkage with socioeconomics of the state of Jammu and Kashmir. During last few decades, anthropogenic pressures in Dal Lake Catchment have caused environmental deterioration impairing, inter-alia, sustained biotic communities and water quality. The present research was an integrated impact analysis of socioeconomic and biophysical processes at the watershed level on the current status of Dal Lake using multi-sensor and multi-temporal satellite data, simulation modelling together with field data verification. Thirteen watersheds (designated as 'W1-W13') were identified and investigated for land use/land cover change detection, quantification of erosion and sediment loads and socioeconomic analysis (total population, total households, literacy rate and economic development status). All the data for the respective watersheds was integrated into the GIS environment based upon multi-criteria analysis and knowledge-based weightage system was adopted for watershed prioritization based on its factors and after carefully observing the field situation. The land use/land cover change detection revealed significant changes with a uniform trend of decreased vegetation and increased impervious surface cover. Increased erosion and sediment loadings were recorded for the watersheds corresponding to their changing land systems, with bare and agriculture lands being the major contributors. The prioritization analysis revealed that W5 > W2 > W6 > W8 > W1 ranked highest in priority and W13 > W3 > W4 > W11 > W7 under medium priority. W12 > W9 > W10 belonged to low-priority category. The integration of the biophysical and the socioeconomic environment at the watershed level using modern geospatial tools would be of vital importance for the conservation and management strategies of Dal Lake ecosystem.

NEW GIS WATERSHED ANALYSIS TOOLS FOR SOIL CHARACTERIZATION AND EROSION AND SEDIMENTATION MODELING

Science.gov (United States)

A comprehensive procedure for computing soil erosion and sediment delivery metrics has been developed which utilizes a suite of automated scripts and a pair of processing-intensive executable programs operating on a personal computer platform.

Global multi-scale segmentation of continental and coastal waters from the watersheds to the continental margins

NARCIS (Netherlands)

Laruelle, G.G.; Dürr, H.H.; Lauerwald, R.; Hartmann, J.; Slomp, C.P.; Goossens, N.; Regnier, P.A.G.

2013-01-01

Past characterizations of the land–ocean continuum were constructed either from a continental perspective through an analysis of watershed river basin properties (COSCATs: COastal Segmentation and related CATchments) or from an oceanic perspective, through a regionalization of the proximal and

Multitemporal analysis of estimated soil loss for the river Mourão watershed, Paraná – Brazil

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C. H. Graça

Full Text Available The multitemporal behavior of soil loss by surface water erosion in the hydrographic basin of the river Mourão in the center-western region of the Paraná state, Brazil, is analyzed. Forecast was based on the application of the Universal Soil Loss Equation (USLE with the data integration and estimates within an Geography Information System (GIS environment. Results had shown high mean annual rain erosivity (10,000 MJ.mm.ha–1.h–1.year–1, with great concentration in January and December. As a rule, soils have average erodibilities, exception of Dystroferric Red Latisol (low class and Dystrophic Red Argisol (high class. Although the topographic factor was high (>20, rates lower than 1 were predominant. Main land uses comprise temporal crops and pasture throughout the years. The watershed showed a natural potential for low surface erosion. When related to usage types, yearly soil loss was also low (<50 ton.ha–1.year–1, with more critical scores that reach rates higher than 150 ton.ha–1.year–1. Soil loss over the years did not provide great distinctions in distribution standards, although it becames rather intensified in some sectors, especially in the center-eastern and southwestern sections of the watershed.

Assessment Of Morphometric Characteristics Of Karwadi-Nandapur Micro Watershed Using Remote Sensing And Geographical Information System

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N.P. Patil

2015-04-01

Full Text Available Abstract The study area is Karwadi-Nandapur watershed is a micro watershed which falls in the Kayadhu river watershed in Marathwada region of Maharashtra. Using the remotely sensed images of the Indian Remote Sensing Satellite P6 IRS P6 Linear Imaging Self Scanner IIILISS III images captured in October 2010 and November 2011 having resolution of 23.5m X 23.5m and images from Google Earth Pro of study area were used and cartosat satellites. Map of India with scale 11500000 and soil maps of India were used for the experimental study. The thematic maps like drainage map land use and land cover map soil maps and contour map were prepared adopting the PCI Geomatica10.0 software. The geographical information systems GIS analysis was made for the said themes using the Arc GIS ArcMap10.0. The Karwadi- Nandapur watershed was found to be the third order basin. The present study aims to assess the morphometric characteristics of the watershed basin and it has been assessed by applying GIS techniques. Strahlers method has been employed to assess the fluvial characteristics of the study watershed. Each morphometric characteristic is considered as a single parameter and knowledge based weight age has been assigned by considering its role in soil erosion. The morphometric properties determined for this watershed as a whole and for each watershed will be useful for the efficient planning of water harvesting and groundwater projects on watershed basis.

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

Erosion and Sedimentation from the Bagley Fire, Eastern Klamath Mountains, Northern CA

Science.gov (United States)

De La Fuente, J. A.; Bachmann, S.; Mai, C.; Mikulovsky, R.; Mondry, Z. J.; Rust, B.; Young, D.

2014-12-01

The Bagley Fire burned about 19,000 hectares on the Shasta-Trinity National Forest in the late summer of 2012, with soil burn severities of 11% high, 19% moderate and 48% low. Two strong storms in November and December followed the fire. The first storm had a recurrence interval of about 2 years, and generated runoff with a return interval of 10-25 years, causing many road stream crossing failures in parts of the fire. The second storm had a recurrence interval of 25-50 years, and initiated more severe erosion throughout the fire area. Erosional processes were dominated by sheet, rill and gully erosion, and landslides were uncommon. A model predicted high potential for debris flows, but few were documented, and though most stream channels exhibited fresh scour and deposition, residual deposits lacked boulder levees or other evidence of debris flow. Rather, deposits were stratified and friable, suggesting a sediment laden flood flow rather than debris flow origin. The resulting sediment was rich in gravel and finer particles, and poor in larger rock. Soil loss was estimated at 0.5-5.6 cm on most hillslopes. A high resolution DEM (LiDAR) was used to measure gullies, small landslides, and stream scour, and also to estimate sedimentation in Squaw Creek, and Shasta Lake. A soil erosion model was used to estimate surface erosion. Total erosion in the Squaw Creek watershed was estimated at 2.24 million metric tons, which equates to 260 metric tons/hectare. Of this, about 0.89 million metric tons were delivered to the stream system (103 metric tons/hectare). Nearly half of this sediment, 0.41 million metric tons, was temporarily stored in the Squaw Creek channel, and around 0.33 million metric tons of fine sediment were carried into Shasta Lake. Squaw Creek also delivered about 0.17 million metric tons of sand, gravel and cobbles to the lake. This estimate is very tenuous, and was made by measuring the volume of a delta in Shasta Lake from a tributary to Squaw Creek and

Quantifying nutrient export and deposition with a dynamic landscape evolution model for the lake Bolsena watershed, Italy

Science.gov (United States)

Pelorosso, Raffaele; Temme, Arnoud; Gobattoni, Federica; Leone, Antonio

2010-05-01

Excessive nutrient loads from upstream watershed activities such as agriculture, hydrological modifications, and urban runoff, have been identified as the leading cause of deterioration in assessed lakes and reservoirs (USEPA, 2000; Leone et al., 2001; Leone et al., 2003). Excessive nutrient transport into lakes and reservoirs may accelerate eutrophication rates, causing negative impacts on aesthetic and water quality. As reservoirs become eutrophic, they are depleted in oxygen and enriched in suspended solids, with heavy consequences for ecosystems and natural habitats. Management of nutrient loads into reservoirs requires knowledge of nutrient transport and delivery from the watershed-stream system (Ripa, 2003). Managing uncultivated lands in watersheds may be a cost effective way to improve water quality in agricultural landscapes, and recent advances in landscape ecology highlight important relationships between the structural configuration of these lands and nutrient redistribution (e.g., Forman 1987; Barrett and others 1990). Many studies have been carried out to underline and explain how landscape characteristics and structure may affect these processes. In these studies, relations between land cover and nutrient storage were analyzed using geographic information systems (GIS) (e.g. Lucas, 2002). Nutrients are generally transported from the landscape into streams during runoff events; however, they may also enter stream flow from other sources such as groundwater recharge and point source effluent discharges (Lucas, 2002; Nielsen, 2007; Waldron, 2008; Castillo, 2009). Water moves nutrients and delivers them to downstream water bodies such as lakes and reservoirs so that erosion phenomena play an essential role in determining nutrients fluxes and deposition. On the one hand, several hydrological models take into account nutrients reactions, movements and deposition - coupling soil erosion processes with transport equations (Bartley, 2004; Lű, 2010). On the

GIBSI: an integrated modelling system for watershed management – sample applications and current developments

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A. N. Rousseau

2007-11-01

Full Text Available Hydrological and pollutant fate models have long been developed for research purposes. Today, they find an application in integrated watershed management, as decision support systems (DSS. GIBSI is such a DSS designed to assist stakeholders in watershed management. It includes a watershed database coupled to a GIS and accessible through a user-friendly interface, as well as modelling tools that simulate, on a daily time step, hydrological processes such as evapotranspiration, runoff, soil erosion, agricultural pollutant transport and surface water quality. Therefore, GIBSI can be used to assess a priori the effect of management scenarios (reservoirs, land use, waste water effluents, diffuse sources of pollution that is agricultural pollution on surface hydrology and water quality. For illustration purposes, this paper presents several management-oriented applications using GIBSI on the 6680 km2 Chaudière River watershed, located near Quebec City (Canada. They include impact assessments of: (i municipal clean water program; (ii agricultural nutrient management scenarios; (iii past and future land use changes, as well as (iv determination of achievable performance standards of pesticides management practices. Current and future developments of GIBSI are also presented as these will extend current uses of this tool and make it useable and applicable by stakeholders on other watersheds. Finally, the conclusion emphasizes some of the challenges that remain for a better use of DSS in integrated watershed management.

Using {sup 137}Cs to quantify the sediment delivery ratio in a small watershed

Energy Technology Data Exchange (ETDEWEB)

Li Mian, E-mail: hnli-mian@163.com [Yellow River Institute of Hydraulic Research, Key Laboratory of Sediment Research of Yellow River of Ministry of Water Resources, Zhengzhou, Henan 450003 (China); Yao Wenyi [Yellow River Institute of Hydraulic Research, Key Laboratory of Sediment Research of Yellow River of Ministry of Water Resources, Zhengzhou, Henan 450003 (China); Li Zhanbin [Xi' an University of Technology, Xi' an, Shaanxi 710048 (China); Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi 712100 (China); Liu Puling [Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi 712100 (China); Yang Er; Shen Zhenzhou [Yellow River Institute of Hydraulic Research, Key Laboratory of Sediment Research of Yellow River of Ministry of Water Resources, Zhengzhou, Henan 450003 (China)

2012-01-15

Understanding the sediment delivery ratio (SDR) is important in controlling sediments for the sustainable development of natural resources and in the design of the construction such as dams and reservoirs. The purpose of this investigation is to determine the SDR by the {sup 137}Cs tracing method in a small watershed in the Sichuan Hilly Basin of China. In the study watershed, different land plots are divided according to the land use type, and 97 sampling sites were selected from these plots. The results show that the average net soil loss rates from the forest land and sloping cultivated land are 1759 and 4468 t/km{sup 2} a, respectively. No {sup 137}Cs was detectable on the bare rock surfaces and previous work showed that the erosion rate from the bare rock area was 14,260 t/km{sup 2} a. In the depositional zone, the sedimentation rates in the Caoto (a kind of cultivated land located at the foot of hills) and paddy field are 3113 and 3562 t/km{sup 2} a, respectively. Combining the area of each land use in the small watershed, the SDR of 0.40 is obtained in the past four decades. The {sup 137}Cs technique was shown to provide an effective and rapid means of estimating the SDR within the small watershed. - Highlights: Black-Right-Pointing-Pointer The erosion and deposition rates can be easily obtained by the {sup 137}Cs tracing method. Black-Right-Pointing-Pointer The {sup 137}Cs method provides an effective means for estimating the SDR. Black-Right-Pointing-Pointer The {sup 137}Cs method is more convenient and rapid than other methods for the SDR research.

Water erosion and climate change in a small alpine catchment

Science.gov (United States)

Berteni, Francesca; Grossi, Giovanna

2017-04-01

WATER EROSION AND CLIMATE CHANGE IN A SMALL ALPINE CATCHMENT Francesca Berteni, Giovanna Grossi A change in the mean and variability of some variables of the climate system is expected to affect the sediment yield of mountainous areas in several ways: for example through soil temperature and precipitation peak intensity change, permafrost thawing, snow- and ice-melt time shifting. Water erosion, sediment transport and yield and the effects of climate change on these physical phenomena are the focus of this work. The study area is a small mountainous basin, the Guerna creek watershed, located in the Central Southern Alps. The sensitivity of sediment yield estimates to a change of condition of the climate system may be investigated through the application of different models, each characterized by its own features and limits. In this preliminary analysis two different empirical mathematical models are considered: RUSLE (Revised Universal Soil Loss Equation; Renard et al., 1991) and EPM (Erosion Potential Method; Gavrilovic, 1988). These models are implemented in a Geographical Information System (GIS) supporting the management of the territorial database used to estimate relevant geomorphological parameters and to create different thematic maps. From one side the geographical and geomorphological information is required (land use, slope and hydrogeological instability, resistance to erosion, lithological characterization and granulometric composition). On the other side the knowledge of the weather-climate parameters (precipitation and temperature data) is fundamental as well to evaluate the intensity and variability of the erosive processes and estimate the sediment yield at the basin outlet. Therefore different climate change scenarios were considered in order to tentatively assess the impact on the water erosion and sediment yield at the small basin scale. Keywords: water erosion, sediment yield, climate change, empirical mathematical models, EPM, RUSLE, GIS

An ecosystem report on the Panama Canal: Monitoring the status of the forest communities and the watershed

Science.gov (United States)

Ibanez, R.; Condit, R.; Angehr, G.; Aguilar, S.; Garcia, T.; Martinez, R.; Sanjur, A.; Stallard, R.; Wright, S.J.; Rand, A.S.; Heckadon, S.

2002-01-01

towns are heavily polluted. Analyses of sediment loads in rivers throughout the watershed did not indicate that erosion has been increasing as a result of deforestation, rather, erosion seems to be driven largely by total rainfall and heavy rainfall events that cause landslides. Still, models suggest that large-scale deforestation would increase landslide frequency, and failure to detect increases in erosion could be due to the gradual deforestation rate and the short time period over which data are available. A study of runoff showed deforestation increased the amount of water from rainfall that passed directly into streams. As a result, dry season flow was reduced in a deforested catchment relative to a forested one. Currently, the Panama Canal watershed has extensive forest areas and streams relatively unaffected by humans. But impacts of hunting and pollution near towns are clear, and the burgeoning population will exacerbate these impacts in the next few decades. Changes in policies regarding forest protection and pollution control are necessary.

Understanding human impacts to tropical coastal ecosystems through integrated hillslope erosion measurements, optical coastal waters characterization, watershed modeling, marine ecosystem assessments, and natural resource valuations in two constrasting watersheds in Puerto Rico.

Science.gov (United States)

Ortiz-Zayas, J.; Melendez, J.; Barreto, M.; Santiago, L.; Torres-Perez, J. L.; Ramos-Scharron, C. E.; Figueroa, Y.; Setegn, S. G.; Guild, L. S.; Armstrong, R.

2017-12-01

Coastal ecosystems are an asset to many tropical island economies. In Puerto Rico, however, many invaluable coastal ecosystems are at risk due to multiple social and natural environmental stressors. To quantify the role of anthropogenic versus natural stressors, an integrated multidisciplinary approach was applied in two contrasting watersheds in Puerto Rico. The Rio Loco (RL) watershed in Southeastern Puerto Rico is hydrologically modified with interbasin water transfers, hydroelectric generation, and with water extraction for irrigation and water supply. Intensive agricultural production dominates both the lower and upper portions of the basin. In contrast, the Rio Grande de Manatí (RGM) shows a natural flow regime with minor flow regulation and limited agriculture. The Surface Water Assessment Tool (SWAT) was applied to each watershed to assess the effects of land use changes on water and sediment fluxes to coastal areas. From 1977 to 2016, forest areas increased in both watersheds due to the abandonment of farms in the mountains. However, in upper and lower RL, agricultural lands have remained active. Coffee plantations in the upper watershed contribute with high sediment loads, particularly in unpaved service roads. We hypothesize that water fluxes will be higher in the larger RGM than in RL. However, suspended sediment fluxes will be higher in the agriculturally active RL basin. A willingness-to-pay approach was applied to assess how residents from each watershed value water and coastal ecosystems revealing a general higher natural resources valuation in the RGM than in RL. Coastal ecosystems at each site revealed structural differences in benthic coral communities due to local currents influenced largely by coastal morphology. The optical properties of coastal waters are also being determined and linked to fluvial sediment fluxes. Stakeholder meetings are being held in each watershed to promote transfer of scientific insights into a sustainable coastal and

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.

Quantitative analysis and implications of drainage morphometry of the Agula watershed in the semi-arid northern Ethiopia

Science.gov (United States)

Fenta, Ayele Almaw; Yasuda, Hiroshi; Shimizu, Katsuyuki; Haregeweyn, Nigussie; Woldearegay, Kifle

2017-11-01

This study aimed at quantitative analysis of morphometric parameters of Agula watershed and its sub-watersheds using remote sensing data, geographic information system, and statistical methods. Morphometric parameters were evaluated from four perspectives: drainage network, watershed geometry, drainage texture, and relief characteristics. A sixth-order river drains Agula watershed and the drainage network is mainly dendritic type. The mean bifurcation ratio ( R b) was 4.46 and at sub-watershed scale, high R b values ( R b > 5) were observed which might be expected in regions of steeply sloping terrain. The longest flow path of Agula watershed is 48.5 km, with knickpoints along the main river which could be attributed to change of lithology and major faults which are common along the rift escarpments. The watershed has elongated shape suggesting low peak flows for longer duration and hence easier flood management. The drainage texture analysis revealed fine drainage which implies the dominance of impermeable soft rock with low resistance against erosion. High relief and steep slopes dominates, by which rough landforms (hills, breaks, and low mountains) make up 76% of the watershed. The S-shaped hypsometric curve with hypsometric integral of 0.4 suggests that Agula watershed is in equilibrium or mature stage of geomorphic evolution. At sub-watershed scale, the derived morphometric parameters were grouped into three clusters (low, moderate, and high) and considerable spatial variability was observed. The results of this study provide information on drainage morphometry that can help better understand the watershed characteristics and serve as a basis for improved planning, management, and decision making to ensure sustainable use of watershed resources.

Minnesota Watersheds

Data.gov (United States)

Minnesota Department of Natural Resources — Statewide minor watershed delineations with major/minor watershed identifiers and names for provinces, major watersheds, and basins. Also included are watershed...

Use of cesium-137 to assess soil erosion rates under soybean, coffee and pasture

International Nuclear Information System (INIS)

Andrello, A.C.; Appoloni, C.R.; Guimaraes, M.F.

2003-01-01

The methodology cesium-137 was used to assess soil erosion and deposition rates in a small watershed with varied crops, at 23 deg 16' S and 51 deg 17' W, in a district of Cambe, Parana State, Brazil. A theoretical equation which considers soil loss or gain directly proportional to the cesium-137 redistribution was utilized in this study. In the watershed, soil redistribution was assessed by transect sampling, and the regional input of cesium-137 by radioactive rainfall determined based on samples from a point in the native forest. Most sampled pasture points presented soil loss, as well as the points in the soybean area under conventional tillage, while in the coffee crop there was neither soil loss nor gain. (author)

Controls and forecasts of nitrate yields in forested watersheds: A view over mainland Portugal.

Science.gov (United States)

Pacheco, F A L; Santos, R M B; Sanches Fernandes, L F; Pereira, M G; Cortes, R M V

2015-12-15

A study on nitrate yields was conducted in forested watersheds of mainland Portugal. The prime goal was to rank parameters in descending order of their contribution to the export of nitrate towards streams and lakes. To attain the goal, variables like soil loss, rainfall intensity, topography, soil type, forest composition and environmental disturbances such as hardwood harvesting or wildfires were organized in a conceptual yield model. Because some parameters were potentially collinear, a robust multivariate statistical technique was selected to execute the conceptual model and perform the aforementioned ranking, namely Partial Least Squares (PLS) regression. This technique was tested with a sample of 60 forested watersheds (>70% of forest occupation), being subject to a double-validation process to ensure prediction capability. According to final regression coefficients, soil erosion seems to regulate nitrate distribution across the basins, because soil loss and type, rainfall intensity and topography explained around 60% of nitrate yield variance. The major importance of erosion is followed by a moderate role of biochemical processes such as nitrification or nutrient uptake, which accounted for approximately 15% of nitrate yield variance. In this case, deciduous forests and scrubland seem to behave as net sinks of nitrate while coniferous and mixed forests seem to act dually, as net sources or sinks. The least important parameters are the environmental disturbances, explaining no more than 5% of nitrate yield variance. The results of PLS regression were coupled in a scenario analysis with measures designed to protect soil from erosion and surface water from eutrophication. These interventions are to be implemented until 2045, according to regional plans of forest management. Considering the key role of erosion in explaining nitrate dynamics across the catchments, it was not surprising to verify that soil protection measures may reduce nitrate yields by some 35

THE EVALUATION OF SOIL EROSION OFF-SITES EFFECTS IN LARGE BASINS: THE STUDYCASE OF LERMA-CHAPALA WATERSHED, MEXICO

OpenAIRE

Helena Cotler A.; Susana Gutierrez D.; Carlos Enriquez G.; Arturo Garrido P.

2005-01-01

One of the primary global concerns during the new millennium is the assessment of the impact of accelerated soil erosion on the economy and the environment (Pimentel et al. 1995; Lal, 1995). Erosion damages the site on which it occurs and also has undesirable effects off-site in the larger environment. Erosion moves sediments and nutrients out of the land, creating the two most widespread water pollution problems in the rivers, lakes and dams. The nutrients impact water quality largely throug...

LOW COST POTENTIAL INFILTRATION ESTIMATION FOR WET TROPICAL WATERSHEDS FOR TERRITORIAL PLANNING SUPPORT

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Franciane Mendonça dos Santos

2016-01-01

Full Text Available This study was developed at Caçula stream watershed of Ilha Solteira (Brazil for potential infiltration estimation based on digital cartography. These methods aim at low-cost and quick analysis processes in order to support the territorial planning. The preliminary potential infiltration chart was produced using ArcHydro and pedological information of the study area. The curve-number method (Soil Conservation Service was used to determine the potential infiltration combining information related to landuse and soil types in the watershed. We also used a methodology that assumes being possible to evaluate potential infiltration of a watershed combining average annual rainfall, land-use and watershed natural attributes (geomorphology, geology and pedology. Results show that ArcHydro is efficient for a preliminary characterization because it shows flow accumulation areas, allowing higher potential of degradation areas in terms of floods, mass movement and erosion. As land-use classes have significant weight in Soil Conservation Service method assessing potential infiltration, this method allow us to evaluate how land-use changes affect water dynamic in the watershed. The propose based on natural environment attributes enables to determine the homologous infiltration areas based on a higher number of natural characteristics of the area, and thereby obtain a result that is closer to the local conditions and, consequently for degradation surface processes identification.

Evaluation of morphometric parameters derived from Cartosat-1 DEM using remote sensing and GIS techniques for Budigere Amanikere watershed, Dakshina Pinakini Basin, Karnataka, India

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Dikpal, Ramesh L.; Renuka Prasad, T. J.; Satish, K.

2017-12-01

The quantitative analysis of drainage system is an important aspect of characterization of watersheds. Using watershed as a basin unit in morphometric analysis is the most logical choice because all hydrological and geomorphic processes occur within the watershed. The Budigere Amanikere watershed a tributary of Dakshina Pinakini River has been selected for case illustration. Geoinformatics module consisting of ArcGIS 10.3v and Cartosat-1 Digital Elevation Model (DEM) version 1 of resolution 1 arc Sec ( 32 m) data obtained from Bhuvan is effectively used. Sheet and gully erosion are identified in parts of the study area. Slope in the watershed indicating moderate to least runoff and negligible soil loss condition. Third and fourth-order sub-watershed analysis is carried out. Mean bifurcation ratio ( R b) 3.6 specify there is no dominant influence of geology and structures, low drainage density ( D d) 1.12 and low stream frequency ( F s) 1.17 implies highly infiltration subsoil material and low runoff, infiltration number ( I f)1.3 implies higher infiltration capacity, coarse drainage texture ( T) 3.40 shows high permeable subsoil, length of overland flow ( L g) 0.45 indicates under very less structural disturbances, less runoff conditions, constant of channel maintenance ( C) 0.9 indicates higher permeability of subsoil, elongation ratio ( R e) 0.58, circularity ratio ( R c) 0.75 and form factor ( R f) 0.26 signifies sub-circular to more elongated basin with high infiltration with low runoff. It was observed from the hypsometric curves and hypsometric integral values of the watershed along with their sub basins that the drainage system is attaining a mature stage of geomorphic development. Additionally, Hypsometric curve and hypsometric integral value proves that the infiltration capacity is high as well as runoff is low in the watershed. Thus, these mormometric analyses can be used as an estimator of erosion status of watersheds leading to prioritization for taking

Hydrology and sediment budget of Los Laureles Canyon, Tijuana, MX: Modelling channel, gully, and rill erosion with 3D photo-reconstruction, CONCEPTS, and AnnAGNPS

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Taniguchi, Kristine; Gudiño, Napoleon; Biggs, Trent; Castillo, Carlos; Langendoen, Eddy; Bingner, Ron; Taguas, Encarnación; Liden, Douglas; Yuan, Yongping

2015-04-01

Several watersheds cross the US-Mexico boundary, resulting in trans-boundary environmental problems. Erosion in Tijuana, Mexico, increases the rate of sediment deposition in the Tijuana Estuary in the United States, altering the structure and function of the ecosystem. The well-being of residents in Tijuana is compromised by damage to infrastructure and homes built adjacent to stream channels, gully formation in dirt roads, and deposition of trash. We aim to understand the dominant source of sediment contributing to the sediment budget of the watershed (channel, gully, or rill erosion), where the hotspots of erosion are located, and what the impact of future planned and unplanned land use changes and Best Management Practices (BMPs) will be on sediment and storm flow. We will be using a mix of field methods, including 3D photo-reconstruction of stream channels, with two models, CONCEPTS and AnnAGNPS to constrain estimates of the sediment budget and impacts of land use change. Our research provides an example of how 3D photo-reconstruction and Structure from Motion (SfM) can be used to model channel evolution.

Hillslope-channel coupling in a steep Hawaiian catchment accelerates erosion rates over 100-fold

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Stock, J. D.; Hanshaw, M. N.; Rosener, M.; Schmidt, K. M.; Brooks, B. A.; Tribble, G.; Jacobi, J.

2009-12-01

In tropical watersheds, hillslope changes are producing increasing amounts of fine sediment that can be quickly carried to reefs by channels. Suspended sediment concentrations off the reefs of Molokai, Hawaii, chronically exceed a toxic level of 10 mg/L, threatening reef ecosystems. We hypothesize that historic conversion of watersheds from soil creep to overland flow erosion increased both magnitude and frequency of sediment flooding adjacent reefs. We combined surficial and ecological mapping, hillslope and stream gages, and novel sensors to locate, quantify and model the generation of fine sediments polluting the Molokai reef. Ecological and geomorphic mapping from LiDAR and multi-spectral imagery located a subset of overland flow areas with vegetation cover below a threshold value preventing erosion. Here, feral goat grazing exposed cohesive volcanic soils whose low matrix hydraulic conductivities (1-20 mm/hour) promote Horton overland flow erosion. We instrumented steep, barren hillslopes with soil moisture sensors, overland flow meters, Parshall flumes, ISCO sediment samplers, and a rain gage and conducted repeat Tripod LiDAR and infiltration tests. To characterize soil resistance here and elsewhere to overland flow erosion, we deployed a Cohesive Strength Meter (CSM) to simulate the stresses of flowing water. At the 13.5 km 2 watershed mouth we used a USGS stream gage and ISCO sediment sampler to estimate total load. Over 2 years, storms triggered overland flow during rainfall intensities above 10-15 mm/hr. Overland flow meters indicate such flows can be up to 3 cm deep, with a tendency to deepen downslope. CSM tests indicate that these depths are insufficient to erode soils where vegetation is dense, but far above threshold values of 2-3 mm depth for bare soil erosion. Sediment ratings curves for both hillslope and downstream catchment gages show strong clock-wise hysteresis during the first intense storms in the Fall, becoming linear later in the rainy

Uso de geoprocessamento na estimativa da perda de solo em microbacia hidrográfica do semiárido brasileiro.= Applied geoprocessing for soil loss estimation in a Brazilian semiarid watershed.

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Luiz Carlos Guerreiro Chaves

2011-08-01

Full Text Available Nowadays soil loss by erosion is one of the most serious environmental problems which has caused the degradation of various resources, especially soil and water. The aim of this study was to predict the soil loss due to erosion at a small watershed sited in Semiarid region of Ceara State, Brazil, through an arrangement of Geographic Information System tools with a quantitative model of soil loss, by the Universal Soil Loss Equation, USLE. The watershed delimitation was performed using the Digital Elevation Model. The density of drainage network was estimated using the extension ArcHydro/ArcMap 9.1. The soil loss in 74% of the studied small watershed presents a value smaller than 11 t ha-1 year-1 in more plain and vegetated areas. It was observe that more than 90% of the area presented a soil loss below 37 t ha-1 year-1, being this characteristic very influenced by the local geography, which is smooth and low sloped in more than 83% of the area of the small watershed. 66% of the area presents a low vulnerability to erosion (<10 t ha-1 year-1, being associated to this region cover vegetation and low values of slope factors. The integrated use of GIS and USLE has allowed a fast and dynamic analysis of the study area, beyond identifying most vulnerable areas to the soil loss process within the basin.

Calculation Methods of Topographic Factors Modification Using Data Digital Elevation Model (DEM To Predict Erosion

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Hengki Simanjuntak

2018-03-01

Full Text Available Erosion  is a crucial information for sustainable management of land resources within a particular watershed. The information of erosion is needed for land resource management planning, and is generally counted by USLE (Universal Soil Loss Equation. One of the parameters in USLE is topographic factor (LS. The determinations of LS in erosion estimation model are vary, both in terms of LS factor equation, as well as in terms of the length of the slope (λ and slope (s measurements. There are at least 3 methods used to calculate slope factors in spatial operation, i.e (1 Input of the LS Value from Table (INT, (2 Flow accumulation, and (3 Cell Size. The study was designed to obtain a method of calculation that gives the smallest topographic factor and in order to obtain a LS factors that similar to the slope information. Research location in Kampa Sub watershed, The LS determination in Kampa Sub watershed basically are with (INT and without calculating λ and s. INT method is determination without calculating λ and s, LS value is generate from the contour map and DEM SRTM by giving LS value from table reference of LS value. The Flow Accumulation and Cell Size are determination of LS Value by calculating λ and s. The Flow Accumulation method modifies the determination of λ and s using the middle value of s, λ per land use, and λ and s per cell. Cell Size method determines λ using the amount of cell size. The results showed that the “cell size” and "INT" methods were the best method for topographic factor (LS calculation, because LS value of “cell size” and "INT" methods are smaller than the flow accumulation method and the LS value similar to the slope information. LS value from that methods generated weighted value in average of 0,55−0,58. Keywords: cell size, flow accumulation, flow direction, the length of the slope, USLE

Application of the SWAT model to the Xiangjiang river watershed in subtropical central China.

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Luo, Qiao; Li, Yong; Wang, Kelin; Wu, Jinshui

2013-01-01

The Soil and Water Assessment Tool (SWAT) model was applied to simulate the water balance in the Xiangjiang river watershed for current and planning scenarios of land uses. The model was first calibrated for the period from 1998 to 2002 and then validated for the period from 2003 to 2007 using the observed stream flow data from four monitoring gages within the watershed. The determination coefficient of linear regression of the observed and simulated monthly stream flows (R(2)) and their Nash-Sutcliffe Index (NSI) was used to evaluate model performance. All values of R(2) and NSI were above 0.8 and ranged from 0.82 to 0.92, which indicates that the SWAT model was capable of simulating the stream flow in the Xiangjiang river watershed. The calibrated and validated SWAT model was then applied to study the hydrological response of three land use change scenarios. Runoff was reduced by increasing the areas of forest and grassland while simultaneously decreasing the areas of agricultural and urban land. In the recent and future land use planning for the Xiangjiang river watershed, the hydrological effect should be considered in regional water management and erosion control.

Extent of Cropland and Related Soil Erosion Risk in Rwanda

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Fidele Karamage

2016-06-01

foster environmental sustainability or further sustainable alternative erosion control techniques may be applied, such as applying Vetiver Eco-engineering Technology due to its economical soil erosion control and stabilization of steep slopes and the construction of erosion control dams to absorb and break down excess runoff from unusually intense storms in various parts of the watersheds.

Preliminary study on the use of the 137Cs method for soil erosion investigation in the pampean region of Argentina

International Nuclear Information System (INIS)

Bujan, A.; Yanez, M.S.; Santanatoglia, O.J.; Chagas, C.; Massobrio, M.; Castiglioni, M.; Ciallella, H.; Fernandez, J.

2000-01-01

Soil erosion is the most important degradation process in Argentine. According to the estimation of 4.9 million ha in Pampa Ondulada Region, 1.600.000 ha (36% of agricultural soils) are affected by the erosion. Field measurements of soil erosion and sediment deposition using classical techniques are difficult, time consuming, and expensive but indispensable to feed the prediction models for conservation practices design and farm planning. Many authors have reported that the measurement of fallout nuclides is useful tool to characterize geomorphical processes. Walling and He proposes models for converting 137 Cs depletion/enrichment amounts to net soil loss/deposition. These models are based in the comparison between a reference 137 Cs profile in a long term undisturbed site (control site) and the 137 Cs profiles in the suspected eroded or deposited sites in the landscape. The aim of this study is to provide a complete and well representative set of data on the erosion intensity in topographical conditions for the Pampa Ondulada Region in Argentine by using a tracer technique. The study area is a small watershed (about 300 ha), located in Arroyo del Tala medium basin, within Partido of San Pedro in Buenos Aires Province, Argentine. This paper presents a group of results from a detailed investigation of erosion and sediment delivery, within a 49 ha cultivated field study site in this watershed. The base of sampling strategy is the grid approach. A reference inventory, representing the local fallout input, was searched for at a site experiencing neither erosion nor deposition. Radiocaesium analyses were made at the Nuclear Regulatory Authority Laboratory by a GE Hp detector. To make an interpretation of 137 Cs distribution of soil losses and sedimentation, the Mass Balance Model 2 was used (Walling and He 1997). The erosion/deposition rates from Mass Balance Model 2 are in the range of 0 to -30 t·ha -1 ·y -1 for erosion, and 0 to 19 t·ha -1 ·y -1 for deposition

Managing Watersheds as Couple Human-Natural Systems: A Review of Research Opportunities

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Cai, X.

2011-12-01

Many watersheds around the world are impaired with severe social and environmental problems due to heavy anthropogenic stresses. Humans have transformed hydrological and biochemical processes in watersheds from a stationary to non-stationary status through direct (e.g., water withdrawals) and indirect (e.g., altering vegetation and land cover) interferences. It has been found that in many watersheds that socio-economic drivers, which have caused increasingly intensive alteration of natural processes, have even overcome natural variability to become the dominant factor affecting the behavior of watershed systems. Reversing this trend requires an understanding of the drivers of this intensification trajectory, and needs tremendous policy reform and investment. As stressed by several recent National Research Council (NRC) reports, watershed management will pose an enormous challenge in the coming decades. Correspondingly, the focus of research has started an evolution from the management of reservoir, stormwater and aquifer systems to the management of integrated watershed systems, to which policy instruments designed to make more rational economic use of water resources are likely to be applied. To provide a few examples: reservoir operation studies have moved from a local to a watershed scale in order to consider upstream best management practices in soil conservation and erosion control and downstream ecological flow requirements and water rights; watersheds have been modeled as integrated hydrologic-economic systems with multidisciplinary modeling efforts, instead of traditional isolated physical systems. Today's watershed management calls for a re-definition of watersheds from isolated natural systems to coupled human-natural systems (CHNS), which are characterized by the interactions between human activities and natural processes, crossing various spatial and temporal scales within the context of a watershed. The importance of the conceptual innovation has been

Mapping environmental land use conflict potentials and ecosystem services in agricultural watersheds.

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Kim, Ilkwon; Arnhold, Sebastian

2018-07-15

In mountainous watersheds, agricultural land use cause changes in ecosystem services, with trade-offs between crop production and erosion regulation. Management of these watersheds can generate environmental land use conflicts among regional stakeholders with different interests. Although several researches have made a start in mapping land use conflicts between human activities and conservation, spatial assessment of land use conflicts on environmental issues and ecosystem service trade-offs within agricultural areas has not been fully considered. In this study, we went further to map land use conflicts between agricultural preferences for crop production and environmental emphasis on erosion regulation. We applied an agricultural land suitability index, based on multi-criteria analysis, to estimate the spatial preference of agricultural activities, while applying the Revised Universal Soil Loss Equation (RUSLE) to reflect the environmental importance of soil erosion. Then, we classified the agricultural catchment into four levels of land use conflicts (lowest, low, high and highest) according to preference and importance of farmland areas, and we compared the classes by crop type. Soil loss in agricultural areas was estimated as 45.1thayr, and agricultural suitability as 0.873; this indicated that land use conflicts in the catchment could arise between severe soil erosion (environmental importance) and agricultural suitability (land preferences). Dry-field farms are mainly located in areas of low land use conflict level, where land preference outweighs environmental importance. When we applied farmland management scenarios with consideration of services, conversion to highest-conflict areas (Scenario 1) as 7.5% of the total area could reduce soil loss by 24.6%, while fallow land management (Scenario 2) could decrease soil loss 19.4% more than the current scenario (Business as usual). The result could maximize land management plans by extracting issues of spatial

Participatory GIS for Soil Conservation in Phewa Watershed of Nepal

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Bhandari, K. P.

2012-07-01

Participatory Geographic Information Systems (PGIS) can integrate participatory methodologies with geo-spatial technologies for the representation of characteristic of particular place. Over the last decade, researchers use this method to integrate the local knowledge of community within a GIS and Society conceptual framework. Participatory GIS are tailored to answer specific geographic questions at the local level and their modes of implementation vary considerably across space, ranging from field-based, qualitative approaches to more complex web-based applications. These broad ranges of techniques, PGIS are becoming an effective methodology for incorporating community local knowledge into complex spatial decision-making processes. The objective of this study is to reduce the soil erosion by formulating the general rule for the soil conservation by participation of the stakeholders. The poster was prepared by satellite image, topographic map and Arc GIS software including the local knowledge. The data were collected from the focus group discussion and the individual questionnaire for incorporate the local knowledge and use it to find the risk map on the basis of economic, social and manageable physical factors for the sensitivity analysis. The soil erosion risk map is prepared by the physical factors Rainfall-runoff erosivity, Soil erodibility, Slope length, Slope steepness, Cover-management, Conservation practice using RUSLE model. After the comparison and discussion among stakeholders, researcher and export group, and the soil erosion risk map showed that socioeconomic, social and manageable physical factors management can reduce the soil erosion. The study showed that the preparation of the poster GIS map and implement this in the watershed area could reduce the soil erosion in the study area compared to the existing national policy.

Soil erosion in a man-made landscape: the Mediterranean

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Cerdà, A.; Ruiz Sinoga, J. D.; Cammeraat, L. H.

2012-04-01

Mediterranean-type ecosystems are characterised by a seasonally contrasted distribution of precipitation, by the coincidence of the driest and hottest season in summer, by an often-mountainous terrain, and by a long history of intense human occupation, especially around the Mediterranean Sea. The history of the Mediterranean lands is the history of human impacts on the soil system, and soil erosion is the most intense and widespread impact on this land where high intensity and uneven rainfall is found. A review of the soil erosion rates measured in the Mediterranean basin will be shown. The measurements done by means of erosion pins, topographical measurements, rainfall simulators, Gerlach collectors in open or close plots, watershed/basin measurements, reservoirs siltation and historical data will be shown. A review of the soil erosion models applied in the Mediterranean will be shown. The tentative approach done until October 2011 show that the soil erosion rates on Mediterranean type ecosystems are not as high as was supposed by the pioneers in the 70's. And this is probably due to the fact that the soils are very shallow and sediments are not available after millennia of high erosion rates. This is related to the large amount of rock fragments are covering the soil, and the rock outcrops that are found in the upper slope trams and the summits. Soil erosion in the Mediterranean is seasonal due to the rainfall concentration in winter, and highly variable within years as the high intensity rainfall events control the sediment production. Natural vegetation is adapted to the Mediterranean environmental conditions, and they are efficient to control the soil losses. An example are the forest fire that increase the soil losses but this is a temporal change as after 2-4 years the soil erosion rates are similar to the pre-fire period. Agriculture lands are the source of sediments although the highest erosion rates are found in badland areas that cover a small part of

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

Spatial and temporal estimation of soil loss for the sustainable management of a wet semi-arid watershed cluster.

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Rejani, R; Rao, K V; Osman, M; Srinivasa Rao, Ch; Reddy, K Sammi; Chary, G R; Pushpanjali; Samuel, Josily

2016-03-01

The ungauged wet semi-arid watershed cluster, Seethagondi, lies in the Adilabad district of Telangana in India and is prone to severe erosion and water scarcity. The runoff and soil loss data at watershed, catchment, and field level are necessary for planning soil and water conservation interventions. In this study, an attempt was made to develop a spatial soil loss estimation model for Seethagondi cluster using RUSLE coupled with ARCGIS and was used to estimate the soil loss spatially and temporally. The daily rainfall data of Aphrodite for the period from 1951 to 2007 was used, and the annual rainfall varied from 508 to 1351 mm with a mean annual rainfall of 950 mm and a mean erosivity of 6789 MJ mm ha(-1) h(-1) year(-1). Considerable variation in land use land cover especially in crop land and fallow land was observed during normal and drought years, and corresponding variation in the erosivity, C factor, and soil loss was also noted. The mean value of C factor derived from NDVI for crop land was 0.42 and 0.22 in normal year and drought years, respectively. The topography is undulating and major portion of the cluster has slope less than 10°, and 85.3% of the cluster has soil loss below 20 t ha(-1) year(-1). The soil loss from crop land varied from 2.9 to 3.6 t ha(-1) year(-1) in low rainfall years to 31.8 to 34.7 t ha(-1) year(-1) in high rainfall years with a mean annual soil loss of 12.2 t ha(-1) year(-1). The soil loss from crop land was higher in the month of August with an annual soil loss of 13.1 and 2.9 t ha(-1) year(-1) in normal and drought year, respectively. Based on the soil loss in a normal year, the interventions recommended for 85.3% of area of the watershed includes agronomic measures such as contour cultivation, graded bunds, strip cropping, mixed cropping, crop rotations, mulching, summer plowing, vegetative bunds, agri-horticultural system, and management practices such as broad bed furrow, raised sunken beds, and harvesting available water

From ridge to reef—linking erosion and changing watersheds to impacts on the coral reef ecosystems of Hawai‘i and the Pacific Ocean

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Stock, Jonathan D.; Cochran, Susan A.; Field, Michael E.; Jacobi, James D.; Tribble, Gordon

2011-01-01

Coral reef ecosystems are threatened by unprecedented watershed changes in the United States and worldwide. These ecosystems sustain fishing and tourism industries essential to the economic survival of many communities. Sediment, nutrients, and pollutants from watersheds are increasingly transported to coastal waters, where these contaminants damage corals. Although pollution from watersheds is one of many factors threatening coral survival, it is one that local people can have a profound influence on. U.S. Geological Survey scientists are using mapping, monitoring, and computer modeling to better forecast the effects of watershed changes on reef health. Working with communities in Hawai‘i and on other U.S. islands in the Pacific, they are helping to provide the science needed to make informed decisions on watershed and coral reef management.

SILTATION AND EROSION PROCESSES ON A TRIBUTARY OF LAKE ITAIPU DUE A DAM RESERVOIR

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Cristiano Poleto

2012-12-01

Full Text Available It is known that sediments in the river have their origin from different sources. Therefore, the proportion that each source contributes to the mix varies over time and space, as a result of erosion processes that are ongoing in the basin of contribution. Within this context, both in human actions in urban and rural watersheds generate different rates of sediment production, but mainly with different characteristics or quality. Thus, the fluvial sedimentology should have a broad character within the study area and check all the possible influences of land use and soil. Hydrosedimentological processes are complex and include a disaggregation ("erosion" in the strict definition, transport, sedimentation, consolidation of sediments. Therefore, it is necessary more detailed studies of sediments and their interactions with the environment, considering it as a topic of interest to economic, social and ecological needs of a sustainable management, where they articulate an understanding of the physical and chemical properties of sediments with ecological and hydrological information of the water bodies receiver on a regional scale and thus evaluate the possible scenarios of pollution of water resources. This information will support in decision-making processes for managing the watershed and its water resources. Therefore, this project aims to determine the interference that a hydroelectric plant, together with the lack of proper management of the basin, can cause to the river morphology. The research is conducting a survey of sensitive areas to erode and the influence of a newly installed hydropower in a tributary of Lake Itaipu. Could notice that the removal of riparian vegetation is accelerating the erosion processes at various points of the river, but the agriculture system used in the rural area, without revolving of soil, has reduced the sediment load produced by this source. However, the retention of much of the coarse sediments by the new dam is

United States‐Mexican border watershed assessment: Modeling nonpoint source pollution in Ambos Nogales

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Norman, Laura M.

2007-01-01

Ecological considerations need to be interwoven with economic policy and planning along the United States‐Mexican border. Non‐point source pollution can have significant implications for the availability of potable water and the continued health of borderland ecosystems in arid lands. However, environmental assessments in this region present a host of unique issues and problems. A common obstacle to the solution of these problems is the integration of data with different resolutions, naming conventions, and quality to create a consistent database across the binational study area. This report presents a simple modeling approach to predict nonpoint source pollution that can be used for border watersheds. The modeling approach links a hillslopescale erosion‐prediction model and a spatially derived sediment‐delivery model within a geographic information system to estimate erosion, sediment yield, and sediment deposition across the Ambos Nogales watershed in Sonora, Mexico, and Arizona. This paper discusses the procedures used for creating a watershed database to apply the models and presents an example of the modeling approach applied to a conservation‐planning problem.

Utilization of Remote Sensing Techniques for Monitoring and Evaluation of Solo Watershed Management

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Totok Gunawan

2004-01-01

Full Text Available This research is an application of remote sensing technology for monitoring and evaluation of watershed management, which was conducted is Solo Watershed, Central and East Java. The research objectives were 1 to investigate the capability of photomorphic analysis of Landsat Thematic Mapper (TM and Enhanced Themmatic Mapper (ETM + imagery as the basic for analyzes of landforms, landuse, and morphometry of the land surface; 2 to calculate the overland flow – peak discharge and erosion – sediment yield as indicators of land degradation of the area; 3 to use the indicators as set of instrument for monitoring and evaluation of watershed management. In this study, visual interpretation by means of on-screen digilization of the digital imagery was carried out in order to identify and to delineate land parameters using photomorphic approach. Based on the photomorphic analysis, several image – based parameters such as relief topography, physical soil characteristic, litho – stratigraphy, and vegetation cover were integrated with other themati maps in a geographic information system (GIS environment. Estimation of overland flow (C based on Cook methods (1942 and calculation of peak disccharge (Qmax based on rational method (Qmax = C. I. A were applied. Meanwhile, estimation of surface erosion was carried out using Universal Soil Loss Equation (USLE, A = R. K. L. S. CP. The sediment yield (Sy was estimated using seddiment delivery ratio ( SDR based on the following formula: Sy = [A + (25% x A] x SDR. Both pairs of C – Qmax and A – Sy, were utilized as the basis for monitoring and evaluation of the watershed. The combination of C – Qmax and A – Sy were also used as the basis for selection of stream gauge setting / AWLR within particular sub – catchment. It was found that the photomorphic analysis is only color/tone, slope aspects, pattern, and texture, unit boundaries between volcanic – origin landscape (Wilis volcanic complex and folded

Land degradation in the Canyoles river watershed, Eastern Spain

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Cerdà, A.; Gonzalez Peñaloza, F. A.; Imeson, A. C.; Gimenez Morera, A.

2012-04-01

Human induced Land Degradation by actions that have a negative impact on the functioning of the environment (Imeson, 2012). Mediterranean arid lands have been intensely transformed by human activity through history, especially due to agricultural management. This intense use of the land resulted in a new man made landscape that is evolving as a consequence of the global change to a new situation that can trigger Land Degradation processes. Extensive areas of olive groves, fruit orchards and vineyards, many of them grown on marginal areas (e.g., terraced slopes) as well as non-sustainable land uses have induced different environmental problems in the Canyoles river watershed (Eastern Spain). The human and physical changes suffered by this region are being used as a representative area of the western Mediterranean basin to monitor how the responses to the Desertification and Land Degradation fit. The aim of this research is to evaluate socio-ecological systems as a part of the Land Ecosystem and Degradation Desertification Response Assessment (LEDDRA) project. This presentation will show the main Land Degradation processes that has been identified: [1] soil erosion as a consequence of agriculture, [2] soil compaction due to herbicide and heavy machinery use, [3] soil sealing on croplands due to heavy vehicles and asphalt and concrete application on roads, [4] soil/water pollution due to agrochemicals, [5] reduction of biodiversity in croplands due to herbicides and substitution of the traditional irrigation system, [6] urbanization processes of rural areas due to the development of urban areas and agricultural infrastructures, [7] monoculture of citrus plantations in the lower part of the watershed, [8] roads and railway construction, [9] aquifer depletion, [10] abandonment of industrial activities, [11] abandonment of local traditional practices for food production and other resources and [12] the effect of land abandonment and wildfires in the nearby mountainous

Disaster Risk Reduction Based on a GIS Case Study of the Čađavica River Watershed

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Ratko Ristić

2017-01-01

Full Text Available Background and Purpose: Although natural hazards cannot be prevented, a better understanding of the processes and scientific methodologies for their prediction can help mitigate their impact. Torrential floods, as one of the consequential forms of the existing erosion processes in synergy with extremely high precipitation, are the most frequent natural hazard at the regional level, which was confirmed by the catastrophic events in May 2014 when huge territories of Serbia, Bosnia and Herzegovina and Croatia were flood-struck. The basic input data for the design of protective structures in torrential beds and watershed slopes are the values of the maximal discharge, area sediment yields, and sediment transport. The calculation of these values requires a careful approach in accordance with the characteristics of torrential watersheds, such as the steepness of slopes and beds in torrential watersheds, intensive erosion processes, favorable conditions for fast runoff formation and the transport of huge quantities of sediment. Materials and Methods: The calculations of maximal discharges, area sediment yields, and sediment transport in the experimental watershed of the Čađavica River were based on using two different spatial resolutions of digital elevations models (DEMs – 20 m resolution DEM, with land use determined from aerial photo images, and the 90 m resolution DEM, with land use determined on the basis of the CORINE database. The computation of maximal discharges was performed by applying a method that combined synthetic unit hydrograph (maximum ordinate of unit runoff qmax and Soil Conservation Service methodologies (deriving effective rainfall Pe from total precipitation Pb. The computation was performed for AMC III (Antecedent Moisture Conditions III – high content of water in the soil and significantly reduced infiltration capacity. The computations of maximal discharges were done taking into account the regional analysis of lag time

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...

Surface and subsurface flow effect on permanent gully formation and upland erosion near Lake Tana in the northern highlands of Ethiopia

Science.gov (United States)

Tebebu, T. Y.; Abiy, A. Z.; Zegeye, A. D.; Dahlke, H. E.; Easton, Z. M.; Tilahun, S. A.; Collick, A. S.; Kidnau, S.; Moges, S.; Dadgari, F.; Steenhuis, T. S.

2010-11-01

Gully formation in the Ethiopian Highlands has been identified as a major source of sediment in water bodies, and results in sever land degradation. Loss of soil from gully erosion reduces agricultural productivity and grazing land availability, and is one of the major causes of reservoir siltation in the Nile Basin. This study was conducted in the 523 ha Debre-Mawi watershed south of Bahir Dar, Ethiopia, where gullies are actively forming in the landscape. Historic gully development in a section of the Debre-Mawi watershed was estimated with semi structured farmer interviews, remotely sensed imagery, and measurements of current gully volumes. Gully formation was assessed by instrumenting the gully and surrounding area to measure water table levels and soil physical properties. Gully formation began in the late 1980's following the removal of indigenous vegetation, leading to an increase in surface and subsurface runoff from the hillsides. A comparison of the gully area, estimated from a 0.58 m resolution QuickBird image, with the current gully area mapped with a GPS, indicated that the total eroded area of the gully increased from 0.65 ha in 2005 to 1.0 ha in 2007 and 1.43 ha in 2008. The gully erosion rate, calculated from cross-sectional transect measurements, between 2007 and 2008 was 530 t ha-1 yr-1 in the 17.4 ha area contributing to the gully, equivalent to over 4 cm soil loss over the contributing area. As a comparison, we also measured rill and interrill erosion rates in a nearby section of the watershed, gully erosion rates were approximately 20 times the measured rill and interrill rates. Depths to the water table measured with piezometers showed that in the actively eroding sections of the gully the water table was above the gully bottom and, in stable gully sections the water table was below the gully bottom during the rainy season. The elevated water table appears to facilitate the slumping of gully walls, which causes the gully to widen and to

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.

Primary factors affecting water quality and quantity in four watersheds in Eastern Puerto Rico

Science.gov (United States)

Murphy, Sheila F.; Stallard, Robert F.

2009-01-01

As part of the U.S. Geological Survey (USGS) Water, Energy, and Biogeochemical Budgets (WEBB) program, four small watersheds in eastern Puerto Rico were monitored to identify and evaluate the effects of geology, landcover, atmospheric deposition, and other factors on stream water quality and quantity. Two catchments are located on coarse-grained granitic plutonic rocks, which weather to quartz- and clay-rich, sandy soils, and two are located on fine-grained volcanic rocks and volcaniclastic sediments, which weather to quartz-poor, fine-grained soils. These differing soil materials result in different hydrologic regimes. Soils on the granitic rocks have greater permeability than those developed on the volcaniclastic rocks, allowing more water infiltration and potentially greater landslide erosion rates. For each bedrock type, one catchment was covered with mature rainforest, and the other catchment was affected by agricultural practices typical of eastern Puerto Rico. These practices led to the erosion of much of the original surface soil in the agricultural watersheds, which introduced large quantities of sediment to stream channels. The agricultural watersheds are undergoing natural reforestation, like much of Puerto Rico. Eastern Puerto Rico receives large atmospheric inputs of marine salts, pollutants from the Northern Hemisphere, and Saharan Desert dust. Marine salts contribute over 80 percent of the ionic charge in precipitation, with peak inputs in January. Intense storms, mostly hurricanes, are associated with exceptionally high chloride concentrations in stream waters. Temperate pollution contributes nitrate, ammonia, and sulfate, with maximum inputs during northern cold fronts in January, April, and May. Pollution inputs have increased through time. Desert dust peaks in June and July, during times of maximum dust transport from the Saharan Desert across the Atlantic Ocean.

Sediment delivery and lake dynamics in a Mediterranean mountain watershed: Human-climate interactions during the last millennium (El Tobar Lake record, Iberian Range, Spain).

Science.gov (United States)

Barreiro-Lostres, Fernando; Brown, Erik; Moreno, Ana; Morellón, Mario; Abbott, Mark; Hillman, Aubrey; Giralt, Santiago; Valero-Garcés, Blas

2015-11-15

Land degradation and soil erosion are key environmental problems in Mediterranean mountains characterized by a long history of human occupation and a strong variability of hydrological regimes. To assess recent trends and evaluate climatic and anthropogenic impacts in these highly human modified watersheds we apply an historical approach combining lake sediment core multi-proxy analyses and reconstructions of past land uses to El Tobar Lake watershed, located in the Iberian Range (Central Spain). Four main periods of increased sediment delivery have been identified in the 8m long sediment sequence by their depositional and geochemical signatures. They took place around 16th, late 18th, mid 19th and early 20th centuries as a result of large land uses changes such as forest clearing, farming and grazing during periods of increasing population. In this highly human-modified watershed, positive synergies between human impact and humid periods led to increased sediment delivery periods. During the last millennium, the lake depositional and geochemical cycles recovered quickly after each sediment delivery event, showing strong resilience of the lacustrine system to watershed disturbance. Recent changes are characterized by large hydrological affections since 1967 with the construction of a canal from a nearby reservoir and a decreased in anthropic pressure in the watershed as rural areas were abandoned. The increased fresh water influx to the lake has caused large biological changes, leading to stronger meromictic conditions and higher organic matter accumulation while terrigenous inputs have decreased. Degradation processes in Iberian Range watersheds are strongly controlled by anthropic activities (land use changes, soil erosion) but modulated by climate-related hydrological changes (water availability, flood and runoff frequency). Copyright © 2015 Elsevier B.V. All rights reserved.

Integrated Universal Soil Loss Equation (USLE) and Geographical Information System (GIS) for Soil Erosion Measurement in basin of Asap river, Central Vietnam

Science.gov (United States)

Pham Gia, Tung; Degener, Jan; Kappas, Martin

2017-04-01

The study was conducted in Asap river basin, A Luoi district, Thua Thien Hue Province, Vietnam, using the Universal Soil Loss Equation (USLE) and Geographical Information System (GIS) to determine the soil erosion status. The results show strong effect of the heavy rainfall and high slope on the erosion level in the research area. More than 40% of land area lost over 10 tons/ha/year. The natural forest land lost the most by averagely is 38.4 tons/ha/year, while the agricultural land showed less with 2.79 tons for paddy rice land use type and 7.58 tons for upland crops yearly. Comparison between some places of Vietnam and the Southeast Asia showed that soil erosion in watersheds of Asap is more serious. We have been proposed a recommendation on changing the classification system of land use type in Vietnam for more accurate in soil erosion measurement. Keywords: Land use type, Soil erosion, USLE, Central Vietnam.

Minor soil erosion contribution to denudation in Central Nepal Himalaya.

Science.gov (United States)

Morin, Guillaume; France-Lanord, Christian; Gallo, Florian; Lupker, Maarten; Lavé, Jérôme; Gajurel, Ananta

2013-04-01

In order to decipher river sediments provenance in terms of erosion processes, we characterized geochemical compositions of hillslope material coming from soils, glaciers and landslide, and compared them to rivers sediments. We focused our study on two South flank Himalayan catchments: (1) Khudi khola, as an example of small High Himalayan catchment (150 km2), undergoing severe precipitation, and rapid erosion ≈ 3.5 mm/yr [A] and (2) the Narayani-Gandak Transhimalayan basin (52000 km2) that drains the whole central Nepal. To assess the question, systematic samplings were conducted on hillslope material from different erosion processes in the basins. River sediment include daily sampling during the 2010 monsoon at two stations, and banks samples in different parts of the basins. Source rocks, soil and landslide samples, are compared to river sediment mobile to immobile element ratios, completed by hydration degree H2O+ analysis[2]. Data show that soils are clearly depleted in mobile elements Na, K, Ca, and highly hydrated compared to source rocks and other erosion products. In the Khudi basin, the contrast between soil and river sediment signatures allow to estimate that soil erosion represents less than 5% of the total sediment exported by the river. Most of the river sediment therefore derives from landslides inputs and to a lesser extent by barren high elevation sub-basins. This is further consistent with direct observation that, during monsoon, significant tributaries of the Khudi river do not export sediments. Considering that active landslide zones represent less than 0.5% of the total watershed area, it implies that erosion distribution is highly heterogeneous. Landslide erosion rate could reach more than 50 cm/yr in the landslide area. Sediments of the Narayani river are not significantly different from those of the Khudi in spite of more diverse geomorphology and larger area of the basin. Only H2O+ and Total Organic Carbon concentrations normalised to Al

Watershed analysis

Science.gov (United States)

Alan Gallegos

2002-01-01

Watershed analyses and assessments for the Kings River Sustainable Forest Ecosystems Project were done on about 33,000 acres of the 45,500-acre Big Creek watershed and 32,000 acres of the 85,100-acre Dinkey Creek watershed. Following procedures developed for analysis of cumulative watershed effects (CWE) in the Pacific Northwest Region of the USDA Forest Service, the...

Climate Change Impacts on Nutrient Losses of Two Watersheds in the Great Lakes Region

Directory of Open Access Journals (Sweden)

Lili Wang

2018-04-01

Full Text Available Non-point sources (NPS of agricultural chemical pollution are one major reason for the water quality degradation of the Great Lakes, which impacts millions of residents in the states and provinces that are bordering them. Future climate change will further impact water quality in both direct and indirect ways by influencing the hydrological cycle and processes of nutrient transportation and transformation, but studies are still rare. This study focuses on quantifying the impacts of climate change on nutrient (Nitrogen and Phosphorus losses from the two small watersheds (Walworth watershed and Green Lake watershed within the Great Lakes region. Analysis focused on changes through this century (comparing the nutrient loss prediction of three future periods from 2015 to 2099 with 30 years for each period against the historical nutrient estimation data from 1985 to 2008. The effects on total phosphorus and nitrate-nitrogen losses due to changes in precipitation quantity, intensity, and frequency, as well as air temperature, are evaluated for the two small watersheds, under three special report emission scenarios (SRES A2, A1B, B1. The newly developed Water Erosion Prediction Project-Water Quality (WEPP-WQ model is utilized to simulate nutrient losses with downscaled and bias corrected future climate forcing from two General Circulation Models (GFDL, HadCM3. For each watershed, the observed runoff and nutrient loads are used to calibrate and validate the model before the application of the WEPP-WQ model to examine potential impacts from future climate change. Total phosphorus loss is projected to increase by 28% to 89% for the Green Lake watershed and 25% to 108% for the Walworth watershed mainly due to the combined effects of increase of precipitation quantity, extreme storm events in intensity and frequency, and air temperature. Nitrate-nitrogen losses are projected to increase by 1.1% to 38% for the Green Lake watershed and 8% to 95% for the

Simulation of the erosion and drainage development of Loess surface based on GIS

Science.gov (United States)

Wang, Chun; Tang, Guoan; Ge, Shanshan; Li, Zhanbin; Zhou, Jieyu

2006-10-01

The research probes into the temporal-spatial process of drainage development of Loess Plateau on the basis of a carefully designed experiment. In the experiment, the development of a simulated loess watershed is tested under the condition of lab-simulated rainfall. A close-range photogrammetry survey is employed to establish a series of high precision and resolution DEM (Digit Elevation Model) of the simulated loess surface. Based on the established DEM, the erosion loss, the slope distribution, the topographic index , the gully-brink, and the drainage networks are all derived and discussed through comparison analysis and experimental validation. All the efforts aim at revealing the process and mechanism of erosion and drainage development of loess surface .This study demonstrates: 1) the stimulation result can effectively reflect the truth if those experimental conditions, i.e. loess soil structure, simulated rainfall, are adjusted in accord with true situation; 2) the remarkable character of the erosion and drainage up-growth of loess surface include the drainage traced to the source, the increased of the drainage's density, the enlarged of gully, the durative variety of multiple terrain factor's mean value and its distribution, such as slope and topographic index; 3) The slope spectrum is the more felicitous terrain factor for depicting the erosion and drainage development of loess surface, including the rule of erosion and evolution process. It is the new way and mean for studying the loess physiognomy.

Check dam sediments: an important indicator of the effects of environmental changes on soil erosion in the Loess Plateau in China.

Science.gov (United States)

Wang, Yafeng; Chen, Liding; Fu, Bojie; Lü, Yihe

2014-07-01

Check dam sediments document the process of soil erosion for a watershed. The main objectives of this research are as follows: first, to determine whether the sediments trapped in check dams can provide useful information about local erosion and the environment, and second, to obtain the extent to which they can be stratigraphically interpreted and correlated to the land use history of an area controlled by check dams. Particle size and the concentration of (137)Cs in sediments are the indicators used to study the effects of environmental changes on soil erosion in the Loess Plateau, China. A total of 216 soil samples were collected from four sediment profile cores at the Yangjuangou watershed check dam constructed in 1955 and fully silted with sediments by 1965. The results indicated that (137)Cs dating and sediment particle size can characterize the sediment deposition process. Silt makes up more than 50 % of the sediment; both the clay and silt sediment fractions decrease gradually in the upstream direction. The sediment profiles are characterized by three depositional layers. These layers suggest changes in the land use. The top layer showed tillage disturbance, with moderate sediments and new soil mixed from 0 to 20 cm. A transition stage from wetlands (characterized by vegetation such as bulrush) to cropland is inferred from sediments at depths of 20-85 cm. Below 85 cm, sedimentary layering is obvious and there is no tillage disturbance. At the downstream site, A0, the average rate of sediment deposition from 1958 to 1963 was approximately 6,125.4 t year(-1) km(-2). Because of their high time resolution, check dam sediments indicate the effects of environmental changes on soil erosion, and they can provide a multiyear record of the soil erosion evolution at the local scale in the middle reaches of the Yellow River.

Predicting watershed sediment yields after wildland fire with the InVEST sediment retention model at large geographic extent in the western USA: accuracy and uncertainties

Science.gov (United States)

Sankey, J. B.; Kreitler, J.; McVay, J.; Hawbaker, T. J.; Vaillant, N.; Lowe, S. E.

2014-12-01

Wildland fire is a primary threat to watersheds that can impact water supply through increased sedimentation, water quality decline, and change the timing and amount of runoff leading to increased risk from flood and sediment natural hazards. It is of great societal importance in the western USA and throughout the world to improve understanding of how changing fire frequency, extent, and location, in conjunction with fuel treatments will affect watersheds and the ecosystem services they supply to communities. In this work we assess the utility of the InVEST Sediment Retention Model to accurately characterize vulnerability of burned watersheds to erosion and sedimentation. The InVEST tools are GIS-based implementations of common process models, engineered for high-end computing to allow the faster simulation of larger landscapes and incorporation into decision-making. The InVEST Sediment Retention Model is based on common soil erosion models (e.g., RUSLE -Revised Universal Soil Loss Equation) and determines which areas of the landscape contribute the greatest sediment loads to a hydrological network and conversely evaluate the ecosystem service of sediment retention on a watershed basis. We evaluate the accuracy and uncertainties for InVEST predictions of increased sedimentation after fire, using measured post-fire sedimentation rates available for many watersheds in different rainfall regimes throughout the western USA from an existing, large USGS database of post-fire sediment yield [synthesized in Moody J, Martin D (2009) Synthesis of sediment yields after wildland fire in different rainfall regimes in the western United States. International Journal of Wildland Fire 18: 96-115]. The ultimate goal of this work is to calibrate and implement the model to accurately predict variability in post-fire sediment yield as a function of future landscape heterogeneity predicted by wildfire simulations, and future landscape fuel treatment scenarios, within watersheds.

Modeling of soil erosion and sediment transport in the East River Basin in southern China

Science.gov (United States)

Wu, Yping; Chen, Ji

2012-01-01

Soil erosion is a major global environmental problem that has caused many issues involving land degradation, sedimentation of waterways, ecological degradation, and nonpoint source pollution. Therefore, it is significant to understand the processes of soil erosion and sediment transport along rivers, and this can help identify the erosion prone areas and find potential measures to alleviate the environmental effects. In this study, we investigated soil erosion and identified the most seriously eroded areas in the East River Basin in southern China using a physically-based model, Soil and Water Assessment Tool (SWAT). We also introduced a classical sediment transport method (Zhang) into SWAT and compared it with the built-in Bagnold method in simulating sediment transport process along the river. The derived spatial soil erosion map and land use based erosion levels can explicitly illustrate the identification and prioritization of the critical soil erosion areas in this basin. Our results also indicate that erosion is quite sensitive to soil properties and slope. Comparison of Bagnold and Zhang methods shows that the latter can give an overall better performance especially in tracking the peak and low sediment concentrations along the river. We also found that the East River is mainly characterized by sediment deposition in most of the segments and at most times of a year. Overall, the results presented in this paper can provide decision support for watershed managers about where the best management practices (conservation measures) can be implemented effectively and at low cost. The methods we used in this study can also be of interest in sediment modeling for other basins worldwide.

Modeling of soil erosion and sediment transport in the East River Basin in southern China.

Science.gov (United States)

Wu, Yiping; Chen, Ji

2012-12-15

Soil erosion is a major global environmental problem that has caused many issues involving land degradation, sedimentation of waterways, ecological degradation, and nonpoint source pollution. Therefore, it is significant to understand the processes of soil erosion and sediment transport along rivers, and this can help identify the erosion prone areas and find potential measures to alleviate the environmental effects. In this study, we investigated soil erosion and identified the most seriously eroded areas in the East River Basin in southern China using a physically-based model, Soil and Water Assessment Tool (SWAT). We also introduced a classical sediment transport method (Zhang) into SWAT and compared it with the built-in Bagnold method in simulating sediment transport process along the river. The derived spatial soil erosion map and land use based erosion levels can explicitly illustrate the identification and prioritization of the critical soil erosion areas in this basin. Our results also indicate that erosion is quite sensitive to soil properties and slope. Comparison of Bagnold and Zhang methods shows that the latter can give an overall better performance especially in tracking the peak and low sediment concentrations along the river. We also found that the East River is mainly characterized by sediment deposition in most of the segments and at most times of a year. Overall, the results presented in this paper can provide decision support for watershed managers about where the best management practices (conservation measures) can be implemented effectively and at low cost. The methods we used in this study can also be of interest in sediment modeling for other basins worldwide. Published by Elsevier B.V.

Evaluating Vegetation Potential for Wildfire Impacted Watershed Using a Bayesian Network Modeling Approach

Science.gov (United States)

Jaramillo, L. V.; Stone, M. C.; Morrison, R. R.

2017-12-01

Decision-making for natural resource management is complex especially for fire impacted watersheds in the Southwestern US because of the vital importance of water resources, exorbitant cost of fire management and restoration, and the risks of the wildland-urban interface (WUI). While riparian and terrestrial vegetation are extremely important to ecosystem health and provide ecosystem services, loss of vegetation due to wildfire, post-fire flooding, and debris flows can lead to further degradation of the watershed and increased vulnerability to erosion and debris flow. Land managers are charged with taking measures to mitigate degradation of the watershed effectively and efficiently with limited time, money, and data. For our study, a Bayesian network (BN) approach is implemented to understand vegetation potential for Kashe-Katuwe Tent Rocks National Monument in the fire-impacted Peralta Canyon Watershed, New Mexico, USA. We implement both two-dimensional hydrodynamic and Bayesian network modeling to incorporate spatial variability in the system. Our coupled modeling framework presents vegetation recruitment and succession potential for three representative plant types (native riparian, native terrestrial, and non-native) under several hydrologic scenarios and management actions. In our BN model, we use variables that address timing, hydrologic, and groundwater conditions as well as recruitment and succession constraints for the plant types based on expert knowledge and literature. Our approach allows us to utilize small and incomplete data, incorporate expert knowledge, and explicitly account for uncertainty in the system. Our findings can be used to help land managers and local decision-makers determine their plan of action to increase watershed health and resilience.

Human-induced C erosion and burial across spatial and temporal scales. (Invited)

Science.gov (United States)

van oost, K.

2013-12-01

Anthropogenic land cover change and soil erosion are tightly coupled: accelerated erosion and deposition of soil are inevitable consequences of the removal of vegetative cover and increased exposure of the soil surface to erosion. A significant portion of the earth surface has now been disturbed and this has locally accelerated erosion 10- to 100-fold. Although there is now growing awareness that the erosion-induced C flux may be an important factor determining global and regional net terrestrial ecosystem C balances, the significance of this disturbance for the past, present and future C cycle remains uncertain. In this paper, we argue that the significance for both past and present C budgets remains poorly quantified due to uncertainty about the contribution of biotic versus erosion-induced C fluxes because of their intrinsically different space and time scales. Carbon erosion research in agro-ecosystems has traditionally focused on short-term processes, i.e. single events to a few decades and longer-term observations of C and sediment dynamics are therefore rare. Likewise, C cycling is typically studied at the profile-scale while erosion processes operate over various spatial scales and whole-watershed approaches are therefore needed. We address this issue here by synthesizing 3 case studies where we report results of a measurement campaign to characterize the erosional control on vertical carbon fluxes from degraded land. First, using signatures in soil sedimentary archives, we integrate the effects of accelerated C erosion across point, hillslope and catchment scale for a temperate river catchment over the period of agriculture to demonstrate that accounting for the non-steady-state C dynamics in geomorphic active systems is pertinent to understand both past and future anthropogenic global change. Secondly, we report year-round soil respiration measurements with high temporal resolution along an erosion gradient on cultivated sloping land in the Chinese Loess

Wireless capsule endoscopy and proximal small bowel lesions in Crohn’s disease

Science.gov (United States)

Petruzziello, Carmelina; Onali, Sara; Calabrese, Emma; Zorzi, Francesca; Ascolani, Marta; Condino, Giovanna; Lolli, Elisabetta; Naccarato, Paola; Pallone, Francesco; Biancone, Livia

2010-01-01

AIM: To investigate the prevalence of proximal small bowel (SB) lesions detected by wireless capsule endoscopy (WCE) in Crohn’s disease (CD). METHODS: WCE was performed in 64 patients: 32 with CD of the distal ileum, and 32 controls with iron-deficiency anemia (IDA) or diarrhea. WCE was performed using the Given SB-WCE, followed by small intestine contrast ultrasonography (SICUS). Findings compatible with CD by using WCE included erosions, aphthoid or deep ulcers, and strictures/stenosis. RESULTS: WCE detected proximal SB lesions in 16/32 (50%) patients (14 aphthoid ulcers, 2 deep ulcers, one stricture), which appeared not to be related to clinical parameters [epigastric pain, age, smoking, non-steroidal anti-inflammatory drugs (NSAIDs), IDA]. Among patients with proximal SB lesions, 6 (37%) were smokers, 3 (19%) NSAID users, 3 (19%) had epigastric pain and 4 (25%) had IDA. SICUS detected proximal SB lesions in 3/32 patients (19%) also showing lesions with WCE. No correlations were observed between proximal SB lesions assessed by WCE or by SICUS (χ2 = 1.5, P = 0.2). CONCLUSION: The use of WCE allows the detection of previously unknown upper SB lesions in a high proportion of patients with a previous diagnosis of CD involving the distal ileum. PMID:20614486

Land factors affecting soil erosion during snow melting: a case study from Lebanon

Science.gov (United States)

Darwich, Talal

2014-05-01

Soil erosion is one of the major problems facing the mountainous agricultural lands in Lebanon. In order to assess the land factors acting on soil erosion; a study was conducted in the upper watershed of Ibrahim River in the spring months of April, May and June. Water and bed load sediments from six locations alimented by six sub-basins were sampled. Four sub-basins (1, 2, 3 and 6) were dominated by agricultural lands while lands in sub-basins 4 and 7 were occupied by grassland and bare soils. The highest quantities of suspended sediments were found in waters originating from watersheds dominated by agricultural lands, such as Location 2 (713.72 mg L-1 in April 2012). Low clay content and the combination of land occupation (orchards = 71%) and slope (20.7 degrees) caused this ecosystem disturbance. Locations 1, 2, 3 and 6 were alimented by runoff water due to the melting of the snow. For this, the concentrations of sediments decreased by 4 fold between April and May in sub-basin 1 and by 11-14 fold in sub-basins 2, 3 and 6. Globally, some 1669.4 tons of sediments were delivered in the upper river during April. Bed load sediments were separated into 4 classes according to their size. The size of the particles found in the bed load reflected to a large extent the type of soils surrounding the watershed. The range of sand in the regions surrounding locations 6 and 7 was 64% and 82%, while the average in the bed load was 80.9% and 78.25% respectively. The silt content in locations 2, 3 and 5 was well reflected in the concentrations of silt in the bed load. In bed load samples, the exchangeable potassium ranged from 70-250 mg kg-1 in sub-basins dominated by agricultural lands against 20-50 mg kg-1 in sub-basins dominated by grassland and bare rocks. Further quantitative studies need to be conducted especially during the first rains to fully estimate the water load sediments after a prolonged dry season, characterizing the east Mediterranean. Action must be taken for

Hillslope Erosion and Water Quality from the Rim Fire, Sierra Nevada, CA

Science.gov (United States)

Kuhn, T. J.; Austin, L. J.; Forrester, H.; DeLong, S. B.; Lever, R.; Roche, J. W.

2014-12-01

The Rim Fire in 2013 burned approximately 1036 km2 in the Sierra Nevada (including 312 km2 within Yosemite National Park), generating considerable public concern regarding potential impacts to the Tuolumne River watershed, in terms of water quality and water supply infrastructure serving the City of San Francisco. Land management responses included a multi-million dollar watershed treatment project on USFS lands near Cherry Creek, with similar actions suggested for areas in the Hetch Hetchy and Lake Eleanor watersheds. In response to the concern that the post-burn landscape will negatively impact water quality, we are investigating hydrologic effects and hillslope erosion in two small burned basins (2.2 and 5.2 km2) within the Tuolumne River basin in Yosemite National Park. Within a month after fire containment, sites were equipped with instrumentation to record stream stage, turbidity, and total suspended sediment. We also installed 21 sediment fences that trap all sediment silt sized and larger on moderate (20%) to steep (50%) hillslopes from 100 m2 plots within moderate and high severity burn areas. Accumulated sediment is collected, weighed, and sub-sampled after each storm event, and, analyzed for dry weight, particle size, gravimetric water content, bulk density, pH, color, carbon and nitrogen content from % fine organics, and % coarse organics. As of July 31, 2014, four discrete storm events had been sampled. Data are used to calculate annual sediment yield, and to investigate organic carbon storage, deposition, and transport. We are also collecting repeat terrestrial laser scans to assess topographic change and identify the hillslope processes that contribute to erosion and deposition at plot- and hillslope-scale. These findings provide analogs for possible changes in adjacent burned areas and to inform management decisions in response to future fires and potential impacts to water quality in areas valued by the park, the City of San Francisco and other

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

Bratney, A. and M. de L. Mendoca-Santos (2008): Digital Soil Mapping for regions and countries with sparse soil data infrastructures. Springer. Xu, Y., Shao, X., Kong, X.-B., Peng, J. and Y.-L. Yun (2008): Adapting the RUSLE and GIS to model soil erosion in a mountainous karst watershed, Guizhou Province, China. Environmental Monitoring Assessment, Vol. 141: 275 - 286.

Regional scale modeling of hill slope sediment delivery: a case study in the Esera-Isabena watershed, central Spanish Pyrenees, with WATEM/SEDEM

Energy Technology Data Exchange (ETDEWEB)

Alatorre, L. C.; Begueria, S.; Garcia-Ruiz, J. M.

2009-07-01

Soil ersoion and sediment delivery to streams is an important environmental problem and a major concern for sustainable development. The spatial nature of soil erosion and sediment delivery, as well as the variety of possible soil conservation and sediment control measures, require an integrated approach to catchment management. A spatially-distributed soil erosion and sediment delivery model (WATEM/SEDEM) was applied to the watershed of the Barasona Reservoir (1504 km{sup 2}, central Spanish Pyrenees), which is drained by the Esera and Isabena rivers. Several input data layers with a 20 x 20 m resolution were derived using a GIS package comprising a digital terrain model (DTM), and stream network, land use, rainfall erosivity, soil erodibility and crop management factors. (Author) 6 refs.

Regional scale modeling of hill slope sediment delivery: a case study in the Esera-Isabena watershed, central Spanish Pyrenees, with WATEM/SEDEM

International Nuclear Information System (INIS)

Alatorre, L. C.; Begueria, S.; Garcia-Ruiz, J. M.

2009-01-01

Soil ersoion and sediment delivery to streams is an important environmental problem and a major concern for sustainable development. The spatial nature of soil erosion and sediment delivery, as well as the variety of possible soil conservation and sediment control measures, require an integrated approach to catchment management. A spatially-distributed soil erosion and sediment delivery model (WATEM/SEDEM) was applied to the watershed of the Barasona Reservoir (1504 km 2 , central Spanish Pyrenees), which is drained by the Esera and Isabena rivers. Several input data layers with a 20 x 20 m resolution were derived using a GIS package comprising a digital terrain model (DTM), and stream network, land use, rainfall erosivity, soil erodibility and crop management factors. (Author) 6 refs.

Watershed management in Myanmar

International Nuclear Information System (INIS)

Choi, K.S.

1993-01-01

Watershed degradation, watershed management, background of watershed management in Myanmar (condition of watershed, manpower), discussion and recommendation (proposed administrative structure, the need for watershed survey and planning, bottom-up approach) are emphasized. Watershed management, after all can be seen that it is the interphase between the forest, agriculture, soil, wildlife and the local communities

Watershed management in Myanmar

Energy Technology Data Exchange (ETDEWEB)

Choi, K S

1993-10-01

Watershed degradation, watershed management, background of watershed management in Myanmar (condition of watershed, manpower), discussion and recommendation (proposed administrative structure, the need for watershed survey and planning, bottom-up approach) are emphasized. Watershed management, after all can be seen that it is the interphase between the forest, agriculture, soil, wildlife and the local communities

Using fluorescence lymphangiography to define the ileocolic mesentery: proof of concept for the watershed area using real-time imaging.

Science.gov (United States)

Keller, D S; Joshi, H M; Rodriguez-Justo, M; Walsh, D; Coffey, J C; Chand, M

2017-09-01

Recent advances in mesenteric science have demonstrated that the mesentery is a continuous structure with a 'watershed' area at the mesenteric apex between the right colon and terminal ileum, where lymphatic flow can proceed either proximally or distally. With this new understanding of the anatomy, functional features are emerging, which can have an impact on surgical management. Fluorescence lymphangiography or lymphoscintigraphy with indocyanine green allows real-time visualization of lymphatic channels, which highlights sentinel lymph nodes and may facilitate identification of the ideal margins for mesenteric lymphadenectomy during bowel resection for colon cancer. By using this novel technology, it is possible to demonstrate a watershed area in the ileocolic region and may facilitate more precise mesenteric dissection. In the present study, we provide proof of concept for the ileocolic watershed area using fluorescence lymphangiography.

Drainage morphometric analysis for assessing form and processes of the watersheds of Pachamalai hills and its adjoinings, Central Tamil Nadu, India

Science.gov (United States)

Prabhakaran, A.; Jawahar Raj, N.

2018-03-01

The present study attempts to understand the form and geomorphic/hydrologic processes of the 20 watersheds of the Pachamalai hills and its adjoinings located in Tamil Nadu State of southern India from the analysis of its drainage morphometric characteristics. Survey of India's topographic sheets of 1:50,000 is the data source from which stream networks and watersheds of the study area were demarcated followed by the analysis of their morphometric characteristics using ArcGIS software. The results of the analysis formed the basis for deducing the form and processes of the watersheds of the study area. The form of the watersheds inferred from the analysis includes shape, length, slope steepness and length, degree of branching of streams, dissection and elongation of watersheds. The geomorphic/hydrologic processes inferred include denudation rate, potential energy, intensity of erosion, mean annual run off, mean discharge, discharge rate, rock resistivity and infiltration potential, amount of sediment transported, mean annual rainfall, rainfall intensity, lagtime, flash flood potential, flood discharge per unit area, sediment yield and speed of the water flow in the streams. The understanding of variations of form and processes mentioned can be used towards prioritizing the watersheds for development, management and conservation planning.

Using high-performance mathematical modelling tools to predict erosion and sediment fluxes in peri-urban catchments

Science.gov (United States)

Pereira, André; Conde, Daniel; Ferreira, Carla S. S.; Walsh, Rory; Ferreira, Rui M. L.

2017-04-01

Deforestation and urbanization generally lead to increased soil erosion andthrough the indirect effect of increased overland flow and peak flood discharges. Mathematical modelling tools can be helpful for predicting the spatial distribution of erosion and the morphological changes on the channel network. This is especially useful to predict the impacts of land-use changes in parts of the watershed, namely due to urbanization. However, given the size of the computational domain (normally the watershed itself), the need for high spatial resolution data to model accurately sediment transport processes and possible need to model transcritical flows, the computational cost is high and requires high-performance computing techniques. The aim of this work is to present the latest developments of the hydrodynamic and morphological model STAV2D and its applicability to predict runoff and erosion at watershed scale. STAV2D was developed at CEris - Instituto Superior Técnico, Universidade de Lisboa - as a tool particularly appropriated to model strong transient flows in complex and dynamic geometries. It is based on an explicit, first-order 2DH finite-volume discretization scheme for unstructured triangular meshes, in which a flux-splitting technique is paired with a reviewed Roe-Riemann solver, yielding a model applicable to discontinuous flows over time-evolving geometries. STAV2D features solid transport in both Euleran and Lagrangian forms, with the aim of describing the transport of fine natural sediments and then the large individual debris. The model has been validated with theoretical solutions and laboratory experiments (Canelas et al., 2013 & Conde et al., 2015). STAV-2D now supports fully distributed and heterogeneous simulations where multiple different hardware devices can be used to accelerate computation time within a unified Object-Oriented approach: the source code for CPU and GPU has the same compilation units and requires no device specific branches, like

Modeling soil erosion and sediment transport from fires in forested watersheds of the South Carolina Piedmont

Science.gov (United States)

Tyler Crumbley; Ge Sun; Steve McNulty

2007-01-01

Forested watersheds in the Southeastern U.S. provide high quality water vital to ecosystem integrity and downstream aquatic resources. Excessive sedimentation from human activities in forest streams is of concern to responsible land managers. Prescribed fire is a common treatment applied to Southeastern Piedmont forests and the risk of wildfire is becoming increasingly...

Modeling soil erosion and sediment transport from fires in forested watersheds of the South Carolina Piedmont

Science.gov (United States)

Tyler Crumbley; Ge Sun; Steve McNulty

2008-01-01

Forested watersheds in the Southeastern U.S. provide high quality water vital to ecosystem integrity and downstream aquatic resources. Excessive sedimentation from human activities in forest streams is of concern to responsible land managers. Prescribed fire is a common treatment applied to Southeastern piedmont forests and the risk of wildfire is becoming increasingly...

Sediment sources of Yan'gou watershed in the Loess Hilly region China under a certain rainstorm event.

Science.gov (United States)

Xu, Xue-Xuan; Ju, Tong-Jun; Zheng, Shi-Qing

2013-01-01

At present the large scale vegetation restoration and intensive oil exploiting had brought huge influence on local environment in Yan'an region. the sediment yield data form series experiment plots and hydrological monitoring station in the Yan'an watershed after one rainfall event on July 2, 2005, which included sediment from different land uses (crop-land plot, vegetation plots, hard road surface) and 3 types roads(mountain-road brunches, mountain-road, and mountain-transport way) has been analyzed. Results showed that the erosion intensity of the 3 type roads was respectively 500 t/km(2), 3163 t/km(2), and 13500 t/km(2). The sediment from cropland and grass, shrub land was within 6-184 t/km(2). It stated that sediment from road area which only covered 1% of total area accounted for 42.3% of the total sediment yield, far beyond that from other uses of land. Sediment from grass-land and shrub-land, which covered 70.5% of watershed area, shared 26.7% of the total sediment. The further analysis showed that the 41.2% of total sediment could be detained by re-vegetation. On the contrary, that road constructing brought heavy sediment which offset the benefit of vegetation restore by 58.4%. the suggestion were to adjust our strategy from slope management to the road erosion mitigation Many studies have confirmed it is an important measure to return the steep slope farming land to green, and to restore vegetation in line with local conditions to prevent soil erosion in the Loess Plateau [1, 2]. To implement the measure in western region, the researches on "Grain for Green", returning farmland to forest and grassland, has become popular [3, 4]. Many scholars studied the effects of farming land and trees and grass land on soil water storage [2, 5]. Tang Keli stated that the slope land for farming was the main source of the sediment in Yellow river, and the maximum gradient slope for farming land use was 25° [6]. Many authorities not only pointed out that a far

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)

Analyzing the impacts of off-road vehicle (ORV) trails on watershed processes in Wrangell-St. Elias National Park and Preserve, Alaska.

Science.gov (United States)

Arp, Christopher D; Simmons, Trey

2012-03-01

Trails created by off-road vehicles (ORV) in boreal lowlands are known to cause local impacts, such as denuded vegetation, soil erosion, and permafrost thaw, but impacts on stream and watershed processes are less certain. In Wrangell-St. Elias National Park and Preserve (WRST), Alaska, ORV trails have caused local resource damage in intermountain lowlands with permafrost soils and abundant wetlands and there is a need to know whether these impacts are more extensive. Comparison of aerial photography from 1957, 1981, and 2004 coupled with ground surveys in 2009 reveal an increase in trail length and number and show an upslope expansion of a trail system around points of stream channel initiation. We hypothesized that these impacts could also cause premature initiation and headward expansion of channels because of lowered soil resistance and greater runoff accumulation as trails migrate upslope. Soil monitoring showed earlier and deeper thaw of the active layer in and adjacent to trails compared to reference sites. Several rainfall-runoff events during the summer of 2009 showed increased and sustained flow accumulation below trail crossings and channel shear forces sufficient to cause headward erosion of silt and peat soils. These observations of trail evolution relative to stream and wetland crossings together with process studies suggest that ORV trails are altering watershed processes. These changes in watershed processes appear to result in increasing drainage density and may also alter downstream flow regimes, water quality, and aquatic habitat. Addressing local land-use disturbances in boreal and arctic parklands with permafrost soils, such as WRST, where responses to climate change may be causing concurrent shifts in watershed processes, represents an important challenge facing resource managers.

Surface and subsurface flow effect on permanent gully formation and upland erosion near Lake Tana in the northern highlands of Ethiopia

Directory of Open Access Journals (Sweden)

T. Y. Tebebu

2010-11-01

Full Text Available Gully formation in the Ethiopian Highlands has been identified as a major source of sediment in water bodies, and results in sever land degradation. Loss of soil from gully erosion reduces agricultural productivity and grazing land availability, and is one of the major causes of reservoir siltation in the Nile Basin. This study was conducted in the 523 ha Debre-Mawi watershed south of Bahir Dar, Ethiopia, where gullies are actively forming in the landscape. Historic gully development in a section of the Debre-Mawi watershed was estimated with semi structured farmer interviews, remotely sensed imagery, and measurements of current gully volumes. Gully formation was assessed by instrumenting the gully and surrounding area to measure water table levels and soil physical properties. Gully formation began in the late 1980's following the removal of indigenous vegetation, leading to an increase in surface and subsurface runoff from the hillsides. A comparison of the gully area, estimated from a 0.58 m resolution QuickBird image, with the current gully area mapped with a GPS, indicated that the total eroded area of the gully increased from 0.65 ha in 2005 to 1.0 ha in 2007 and 1.43 ha in 2008. The gully erosion rate, calculated from cross-sectional transect measurements, between 2007 and 2008 was 530 t ha⁻¹ yr⁻¹ in the 17.4 ha area contributing to the gully, equivalent to over 4 cm soil loss over the contributing area. As a comparison, we also measured rill and interrill erosion rates in a nearby section of the watershed, gully erosion rates were approximately 20 times the measured rill and interrill rates. Depths to the water table measured with piezometers showed that in the actively eroding sections of the gully the water table was above the gully bottom and, in stable gully sections the water table was below the gully bottom during the rainy season. The elevated water table appears to facilitate the slumping of gully

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

Evaluation of spatial plan in controlling stream flow rate in Wakung Watershed, Pemalang, Central Java, Indonesia

Science.gov (United States)

Anwar, Y.; Setyasih, I.; Setiawan, M. A.; Christanto, N.

2018-04-01

Evaluation study for such a regional spatial plan (RTRW) in Indonesia has not been evaluated for its effectiveness in controlling the surface run off that contributed to streamflow. This necessity can be accomplishsed by applying a modeling approach, such as Soil Water Assessment Tool (SWAT). The objectives of this research are 1) to simulate the streamflow of Wakung watershed based on actual landuse, 2) to predict streamflow of Wakung watershed based on RTRW, and 3) to evaluate the effectiveness of the RTRW of Pemalang District in controling streamflow rate at Wakung Watershed. ArcSWAT model was used to determine the erosion rate prediction. The model was then calibrated by using SWATCUP. Model performance were tested by using R2 and ENS. The calibration and validation results showed that R2 and ENS (monthly) > 0.5. The result of SWAT simulation in Wakung sub-watershed reaching 161 - 4950 m3/s/years for W-A scenario (actual landuse and weather data of 2013), for scenario W-R (RTRW and weather data of 2013), 330 - 4919 m3/s/year. The comparison between actual and spatial plan land use data for stream flow is showing that the W-A scenario is lower than the W-R scenario in 19 sub watersheds. This is because there are many plans for adding land use for urban and intensive horticulture land in areas with steep slopes (> 25%). This condition is caused by the demands of fulfilling the needs of settlement and food for people in the Wakung watershed.

Hydro-ecological degradation due to human impacts in the Twin Streams Watershed, Auckland, New Zealand

Science.gov (United States)

Torrecillas Nunez, C.; Miguel-rodriguez, A.

2012-12-01

As a collaborative project between the Faculties of Engineering of the University of Sinaloa, Mexico and the University of Auckland, an inter-disciplinary team researched historical information, monitoring results and modelling completed over the last ten years to establish the cause-effect relationship of development and human impacts in the watershed and recommend strategies to offset them .The research program analyzed the performance of the Twin Streams watershed over time with modelling of floods, hydrological disturbance indicators, analysis of water quality and ecological information, cost / benefit, harbor modelling and contaminant loads. The watershed is located in the west of Auckland and comprises 10,356 hectare: 8.19% ecologically protected area, 29.70% buffer zone, 6.67% peri-urban, 30.98% urban, 16.04% parks, and 8.42% other; average impermeability is 19.1%. Current population is 129,475 (2011) forecast to grow to 212,798 by 2051. The watershed includes 317.5 km of streams that drain to the Waitemata Harbor. The human impact can be traced back to the 1850s when the colonial settlers logged the native forests, dammed streams and altered the channel hydro-ecology resulting in significant erosion, sediment and changes to flows. In the early 1900s native vegetation started to regenerate in the headwaters, while agriculture and horticulture become established in rest of the watershed leading to the use of quite often very harmful pesticides and insecticides, such as DDT which is still detected in current environmental monitoring programs, and more erosion and channel alterations. As land become unproductive in the 1950s it stared to be urbanized, followed by more intensive urban development in the 1990s. Curiously there was no regulatory regime to control land use in the early stages and consequently over 400 houses were built in the floodplains, as well there were no legislation to control environmental impacts until 1991. Consequently today there is a

Late Holocene Environmental History of the Los Osos Watershed, Morro Bay, CA

Science.gov (United States)

Broadman, E.; Reidy, L. M.; Wahl, D.

2014-12-01

A comprehensive understanding of past changes in wetland ecosystems is integral for creating policies for modern land use practices. The Morro Bay salt marsh is home to a large wetland that has experienced significant environmental impacts in the last few centuries. In this study, sediment cores from the Morro Bay salt marsh were analyzed to discern changes in environment since the time of European contact, which occurred in 1772. The marsh is fed by two creeks (Chorro and Los Osos) and their associated watersheds. Sediment cores taken from a portion of the marsh fed by Los Osos creek were analyzed and the results compared to those from previous studies on cores taken from the Chorro and Los Osos portions of the marsh. Magnetic susceptibility, loss on ignition, pollen, radiocarbon, and X-ray fluorescence (XRF) analyses were conducted. An age-depth model was established for the Los Osos cores using two radiocarbon dates, as well as Erodium cicutarium as a chronological marker. Preliminary pollen analysis from Chorro marsh cores indicates vegetation shifts at the time of contact, when the salt marsh formed. Magnetic susceptibility and XRF data indicate dramatically increased rates of erosion from the time of contact consistently until the present. Influx of non-carbonate inorganic material also indicates a rapid increase in sedimentation in the marsh starting at the time of contact. Comparison of sedimentation rates between the two creeks suggests that differences in watershed geomorphology and land use practices have had pronounced impacts on erosional processes. Over the last decade, the Morro Bay National Estuary Program (MBNEP) has taken more measures to reduce erosion and sedimentation rates in the Chorro watershed, as is reflected by reduced sedimentation rates in MBNEP data collected within the last few years. Our study helps to elucidate the impacts of anthropogenic land use change on wetland systems, and provides much needed data to policy makers seeking to

Comparison of the Effects of the Different Methods for Computing the Slope Length Factor at a Watershed Scale

Directory of Open Access Journals (Sweden)

Fu Suhua

2013-09-01

Full Text Available The slope length factor is one of the parameters of the Universal Soil Loss Equation (USLE and the Revised Universal Soil Loss Equation (RUSLE and is sometimes calculated based on a digital elevation model (DEM. The methods for calculating the slope length factor are important because the values obtained may depend on the methods used for calculation. The purpose of this study was to compare the difference in spatial distribution of the slope length factor between the different methods at a watershed scale. One method used the uniform slope length factor equation (USLFE where the effects of slope irregularities (such as slope gradient, etc. on soil erosion by water were not considered. The other method used segmented slope length factor equation(SSLFE which considered the effects of slope irregularities on soil erosion by water. The Arc Macro Language (AML Version 4 program for the revised universal soil loss equation(RUSLE.which uses the USLFE, was chosen to calculate the slope length factor. In a parallel analysis, the AML code of RUSLE Version 4 was modified according to the SSLFE to calculate the slope length factor. Two watersheds with different slope and gully densities were chosen. The results show that the slope length factor and soil loss using the USLFE method were lower than those using the SSLFE method, especially on downslopes watershed with more frequent steep slopes and higher gully densities. In addition, the slope length factor and soil loss calculated by the USLFE showed less spatial variation.

Evaluation of different machine learning models for predicting and mapping the susceptibility of gully erosion

Science.gov (United States)

Rahmati, Omid; Tahmasebipour, Nasser; Haghizadeh, Ali; Pourghasemi, Hamid Reza; Feizizadeh, Bakhtiar

2017-12-01

Gully erosion constitutes a serious problem for land degradation in a wide range of environments. The main objective of this research was to compare the performance of seven state-of-the-art machine learning models (SVM with four kernel types, BP-ANN, RF, and BRT) to model the occurrence of gully erosion in the Kashkan-Poldokhtar Watershed, Iran. In the first step, a gully inventory map consisting of 65 gully polygons was prepared through field surveys. Three different sample data sets (S1, S2, and S3), including both positive and negative cells (70% for training and 30% for validation), were randomly prepared to evaluate the robustness of the models. To model the gully erosion susceptibility, 12 geo-environmental factors were selected as predictors. Finally, the goodness-of-fit and prediction skill of the models were evaluated by different criteria, including efficiency percent, kappa coefficient, and the area under the ROC curves (AUC). In terms of accuracy, the RF, RBF-SVM, BRT, and P-SVM models performed excellently both in the degree of fitting and in predictive performance (AUC values well above 0.9), which resulted in accurate predictions. Therefore, these models can be used in other gully erosion studies, as they are capable of rapidly producing accurate and robust gully erosion susceptibility maps (GESMs) for decision-making and soil and water management practices. Furthermore, it was found that performance of RF and RBF-SVM for modelling gully erosion occurrence is quite stable when the learning and validation samples are changed.

Watershed Evaluation and Habitat Response to Recent Storms : Annual Report for 1999.

Energy Technology Data Exchange (ETDEWEB)

Rhodes, Jonathan J.; Huntington, Charles W.

2000-02-01

Large and powerful storm systems moved through the Pacific Northwest during the wet season of 1995--96, triggering flooding, mass erosion, and, alteration of salmon habitats in affected watersheds. This project study was initiated to assess whether watershed conditions are causing damage, triggered by storm events, to salmon habitat on public lands in the Snake River basin. The storms and flooding in 1995--96 provide a prime opportunity to examine whether habitat conditions are improving, because the effects of land management activities on streams and salmon habitat are often not fully expressed until triggered by storms and floods. To address these issues, they are studying the recent storm responses of watersheds and salmon habitat in systematically selected subbasins and watersheds within the Snake River system. The study watersheds include several in the Wenaha and Tucannon subbasins in Washington and Oregon, and the watersheds of Squaw Creek (roaded) and Weir Creek (unroaded) in the Lochsa River subbasin, Idaho. The study was designed to examine possible differences in the effects of the storms in broadly comparable watersheds with differing magnitudes or types of disturbance. Watershed response is examined by comparing storm response mechanisms, such as rates of mass failure, among watersheds with similar attributes, but different levels of land management. The response of salmon habitat conditions is being examined by comparing habitat conditions before and after the storms in a stream and among streams in watersheds with similar attributes but different levels of land management. If appropriate to the results, the study will identify priority measures for reducing the severity of storm responses in watersheds within the Snake River Basin with habitat for at-risk salmon. This annual report describes the attributes of the study watersheds and the criteria and methods used to select them. The report also describes the watershed and fish habitat attributes

Watershed evaluation and habitat response to recent storms; annual report for 1999

International Nuclear Information System (INIS)

Rhodes, Jonathan J.; Huntington, Charles W.

2000-01-01

Large and powerful storm systems moved through the Pacific Northwest during the wet season of 1995--96, triggering flooding, mass erosion, and, alteration of salmon habitats in affected watersheds. This project study was initiated to assess whether watershed conditions are causing damage, triggered by storm events, to salmon habitat on public lands in the Snake River basin. The storms and flooding in 1995--96 provide a prime opportunity to examine whether habitat conditions are improving, because the effects of land management activities on streams and salmon habitat are often not fully expressed until triggered by storms and floods. To address these issues, they are studying the recent storm responses of watersheds and salmon habitat in systematically selected subbasins and watersheds within the Snake River system. The study watersheds include several in the Wenaha and Tucannon subbasins in Washington and Oregon, and the watersheds of Squaw Creek (roaded) and Weir Creek (unroaded) in the Lochsa River subbasin, Idaho. The study was designed to examine possible differences in the effects of the storms in broadly comparable watersheds with differing magnitudes or types of disturbance. Watershed response is examined by comparing storm response mechanisms, such as rates of mass failure, among watersheds with similar attributes, but different levels of land management. The response of salmon habitat conditions is being examined by comparing habitat conditions before and after the storms in a stream and among streams in watersheds with similar attributes but different levels of land management. If appropriate to the results, the study will identify priority measures for reducing the severity of storm responses in watersheds within the Snake River Basin with habitat for at-risk salmon. This annual report describes the attributes of the study watersheds and the criteria and methods used to select them. The report also describes the watershed and fish habitat attributes

Mapping watershed potential to contribute phosphorus from geologic materials to receiving streams, southeastern United States

Science.gov (United States)

Terziotti, Silvia; Hoos, Anne B.; Harned, Douglas; Garcia, Ana Maria

2010-01-01

As part of the southeastern United States SPARROW (SPAtially Referenced Regressions On Watershed attributes) water-quality model implementation, the U.S. Geological Survey created a dataset to characterize the contribution of phosphorus to streams from weathering and erosion of surficial geologic materials. SPARROW provides estimates of total nitrogen and phosphorus loads in surface waters from point and nonpoint sources. The characterization of the contribution of phosphorus from geologic materials is important to help separate the effects of natural or background sources of phosphorus from anthropogenic sources of phosphorus, such as municipal wastewater or agricultural practices. The potential of a watershed to contribute phosphorus from naturally occurring geologic materials to streams was characterized by using geochemical data from bed-sediment samples collected from first-order streams in relatively undisturbed watersheds as part of the multiyear U.S. Geological Survey National Geochemical Survey. The spatial pattern of bed-sediment phosphorus concentration is offered as a tool to represent the best available information at the regional scale. One issue may weaken the use of bed-sediment phosphorus concentration as a surrogate for the potential for geologic materials in the watershed to contribute to instream levels of phosphorus-an unknown part of the variability in bed-sediment phosphorus concentration may be due to the rates of net deposition and processing of phosphorus in the streambed rather than to variability in the potential of the watershed's geologic materials to contribute phosphorus to the stream. Two additional datasets were created to represent the potential of a watershed to contribute phosphorus from geologic materials disturbed by mining activities from active mines and inactive mines.

Influence of declining mean annual rainfall on the behavior and yield of sediment and particulate organic carbon from tropical watersheds

Science.gov (United States)

Ayron M. Strauch; Richard A. MacKenzie; Christian P. Giardina; Gregory L. Bruland

2018-01-01

The capacity to forecast climate and land-use driven changes to runoff, soil erosion and sediment transport in the tropics is hindered by a lack of long-term data sets and model study systems. To address these issues we utilized three watersheds characterized by similar shape, geology, soils, vegetation cover, and land use arranged across a 900 mm gradient in mean...

Methodology to evaluate the impact of the erosion in cultivated floors applying the technique of the 137CS

International Nuclear Information System (INIS)

Gil Castillo, R.; Peralta Vital, J.L.; Carrazana, J.; Riverol, M.; Penn, F.; Cabrera, E.

2004-01-01

The present paper shows the results obtained in the framework of 2 Nuclear Projects, in the topic of application of nuclear techniques to evaluate the erosion rates in cultivated soils. Taking into account the investigations with the 137 CS technique, carried out in the Province of Pinar del Rio, was obtained and validated (first time) a methodology to evaluate the erosion impact in a cropland. The obtained methodology includes all relevant stages for the adequate application of the 137 CS technique, from the initial step of area selection, the soil sampling process, selection of the models and finally, the results evaluation step. During the methodology validation process in soils of the Municipality of San Juan y Martinez, the erosion rates estimated by the methodology and the obtained values by watershed segment measures (traditional technique) were compared in a successful manner. The methodology is a technical guide, for the adequate application of the 137 CS technique to estimate the soil redistribution rates in cultivated soils

Effects of land use and management on aggregate stability and hydraulic conductivity of soils within River Njoro Watershed in Kenya

Directory of Open Access Journals (Sweden)

Zachary G. Mainuri

2013-09-01

Full Text Available There has been tremendous changes in land use and management in the River Njoro Watershed during the last three decades. Formerly large scale farms have been converted into smallholder farms and plantation forests have gradually been lost. These changes in land use and management have brought in different approaches that have triggered soil erosion and other forms of land degradation. The objective of this study was to trace the changes in land use and determine their effects on aggregate stability and hydraulic conductivity. A semi detailed soil survey of the watershed was undertaken following a three-tier approach comprising image interpretation, field surveys and laboratory analysis. The measured variables in the soil were analysed using ANOVA and correlation analysis. The major land uses were found to be forestland, agricultural land, grassland, and wetland. A strong soil type _ landscape relationship was observed within the watershed. Soils of slopes were moderately to severely eroded, shallow and less developed whereas those on summits, pen plains, uplands, plateaus and valleys were deep and well developed. Aggregate stability was the highest in forestland and decreased in the order of grassland, agricultural land and wetland respectively. The mean weight diameter under the various land use conditions was 0.68, 0.64, 0.58, and 0 41 respectively. Hydraulic conductivity was the highest in forest-land and decreased in the order of agricultural land, grassland and wetland respectively. There was significant negative correlation between hydraulic conductivity and the bulk density and clay content of the soils. Reduced aggregate stability and lowered hydraulic conductivity is likely to be responsible for some of the severe soil erosion and other forms of land degradation observed in the River Njoro Watershed.

A Stream Erosion Susceptibility Identification Tool for use in Hydromodification Planning

Science.gov (United States)

Berntsen, E.; Bowles, C.

2008-12-01

A stream erosion susceptibility identification tool has been developed for use in hydromodification planning based on a three-tiered approach. Tier 1 involved development of a susceptibility map. This included conducting a watershed scale GIS- and remote sensing-based screening analysis of two methodologies to quantify stream susceptibility to hydromodification. Tier 2 will involve conducting rapid geomorphic assessments for selected areas that were screened to have high and low erosion potential in Tier 1. Tier 3 will identify key geomorphic thresholds (e.g., relationship between channel slope, median particle size, and drainage area for stable and unstable channels, critical bank heights in various channel materials, channel response to changes in flow and sediment supply, etc.) from comparison of stable and unstable channels. This poster will primarily cover the methodology and results in Tier 1 for a pilot project in the Laguna Creek Watershed in Sacramento County, California. We used two methodologies, relying on readily available topographic information (i.e., USGS 10-meter DEM), for producing the Tier 1 susceptibility map: Hack's relationship (Hack, 1957; Bledsoe and Watson, 2004) and specific stream power (Simons and Downs, 1995). Hack's relationship involved calculating the hydraulic stability number (Nh), which is the ratio of the existing channel slope to the corresponding equilibrium slope, whereby a value greater than 1 represents a relatively unstable channel. Specific stream power involved calculating the power expended per unit area of the streambed (in Watts/m2), whereby a value greater than 35 represents a relatively unstable channel. The results of the Tier 1 analysis indicated that the two methodologies compared favorably in their predictions of channel instability. Comparisons of the two methodologies were also made with existing channel conditions as observed by others in a recent study in the watershed and completed in 2007. As shown by this

Fluvial responses to land-use changes and climatic variations within the Drury Creek watershed, southern Illinois

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Miller, Suzanne Orbock; Ritter, Dale F.; Kochel, R. Craig; Miller, Jerry R.

1993-04-01

Fluvial responses to climatic variation and Anglo-American settlement were documented for the Drury Creek watershed, southern Illinois by examining stratigraphic, geomorphic, climatic, and historical data. Regional analyses of long-term precipitation records document a period of decreasing mean annual precipitation from 1904 to about 1945, and an increasing trend in annual precipitation from 1952 to the present. The period between 1945 and 1951 experienced a large number of intense storms that resulted in high annual precipitation totals. Statistical relationships illustrate that changes in precipitation totals are transferred to the hydrologic system as fluctuations in stream discharge. Historical records of southern Illinois show that a maximum period of settlement and deforestation occurred between the 1860s and 1920s. This era ended in the 1940s when large tracts of land were revegetated in an attempt to curtail erosion which had caused extensive upland degradation. In response to hillslope erosion at least two meters of fine-grained sediments were deposited on valley floors. Average sedimentation rates, determined using decdrochronologic techniques, are estimated to be 2.11 cm/yr for the period between 1890 and 1988; rates that are 1 to 2 orders of magnitude greater than pre-settlement values calculated for other areas of the midwest. However, botanical data suggest that aggradation was episodic, possibly occurring during three periods characterized by greater annual precipitation. Since the 1940s, sedimentation rates have declined. Reduced rates of sedimentation are related to an episode of channel entrenchment that reduced overbank flooding. Entrenchment coincided with a period of: (1) reduced sediment yields associated with watershed revegetation and the introduction of soil conservation practices, and (2) intense storm activity that resulted in long periods of high discharge. As a result of channel incision and hillslope erosion, newly exposed bedrock in

A new watershed assessment framework for Nova Scotia: A high-level, integrated approach for regions without a dense network of monitoring stations

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Sterling, Shannon M.; Garroway, Kevin; Guan, Yue; Ambrose, Sarah M.; Horne, Peter; Kennedy, Gavin W.

2014-11-01

High-level, integrated watershed assessments are a basic requirement for freshwater planning, as they create regional summaries of multiple environmental stressors for the prioritization of watershed conservation, restoration, monitoring, and mitigation. There is a heightened need for a high-level, integrated watershed assessment in Nova Scotia as it faces pressing watershed issues relating to acidification, soil erosion, acid rock drainage, eutrophication, and water withdrawals related to potential shale gas development. But because of the relative sparseness of the on-the-ground effects-based data, for example on water quality or fish assemblages, previously created approaches for integrated watershed assessment cannot be used. In a government/university collaboration, we developed a new approach that relies solely on easier-to-collect and more available exposure-based variables to perform the first high-level watershed assessment in Nova Scotia. In this assessment, a total of 295 watershed units were studied. We used Geographic Information Systems (GIS) to map and analyze 13 stressor variables that represent risks to aquatic environment (e.g., road/stream crossing density, acid rock drainage risk, surface water withdrawals, human land use, and dam density). We developed a model to link stressors with impacts to aquatic systems to serve as a basis for a watershed threat ranking system. Resource management activities performed by government and other stakeholders were also included in this analysis. Our assessment identifies the most threatened watersheds, enables informed comparisons among watersheds, and indicates where to focus resource management and monitoring efforts. Stakeholder communication tools produced by the NSWAP include a watershed atlas to communicate the assessment results to a broader audience, including policy makers and public stakeholders. This new framework for high-level watershed assessments provides a resource for other regions that also

Turbidity Responses from Timber Harvesting, Wildfire, and Post-Fire Logging in the Battle Creek Watershed, Northern California.

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Lewis, Jack; Rhodes, Jonathan J; Bradley, Curtis

2018-04-11

The Battle Creek watershed in northern California was historically important for its Chinook salmon populations, now at remnant levels due to land and water uses. Privately owned portions of the watershed are managed primarily for timber production, which has intensified since 1998, when clearcutting became widespread. Turbidity has been monitored by citizen volunteers at 13 locations in the watershed. Approximately 2000 grab samples were collected in the 5-year analysis period as harvesting progressed, a severe wildfire burned 11,200 ha, and most of the burned area was salvage logged. The data reveal strong associations of turbidity with the proportion of area harvested in watersheds draining to the measurement sites. Turbidity increased significantly over the measurement period in 10 watersheds and decreased at one. Some of these increases may be due to the influence of wildfire, logging roads and haul roads. However, turbidity continued trending upwards in six burned watersheds that were logged after the fire, while decreasing or remaining the same in two that escaped the fire and post-fire logging. Unusually high turbidity measurements (more than seven times the average value for a given flow condition) were very rare (0.0% of measurements) before the fire but began to appear in the first year after the fire (5.0% of measurements) and were most frequent (11.6% of measurements) in the first 9 months after salvage logging. Results suggest that harvesting contributes to road erosion and that current management practices do not fully protect water quality.

Lawrence Livermore National Laboratory Surface Water Protection: A Watershed Approach

Energy Technology Data Exchange (ETDEWEB)

Coty, J

2009-03-16

is largely developed yet its surface water system encompasses two arroyos, an engineered detention basin (Lake Haussmann), storm channels, and wetlands. Conversely, the more rural Site 300 includes approximately 7,000 acres of largely undeveloped land with many natural tributaries, riparian habitats, and wetland areas. These wetlands include vernal pools, perennial seeps, and emergent wetlands. The watersheds within which the Laboratory's sites lie provide local and community ecological functions and services which require protection. These functions and services include water supply, flood attenuation, groundwater recharge, water quality improvement, wildlife and aquatic habitats, erosion control, and (downstream) recreational opportunities. The Laboratory employs a watershed approach to protect these surface water systems. The intent of this approach, presented in this document, is to provide an integrated effort to eliminate or minimize any adverse environmental impacts of the Laboratory's operations and enhance the attributes of these surface water systems, as possible and when reasonable, to protect their value to the community and watershed. The Laboratory's watershed approach to surface water protection will use the U.S. Environmental Protection Agency's Watershed Framework and guiding principles of geographic focus, scientifically based management and partnerships1 as a foundation. While the Laboratory's unique site characteristics result in objectives and priorities that may differ from other industrial sites, these underlying guiding principles provide a structure for surface water protection to ensure the Laboratory's role in environmental stewardship and as a community partner in watershed protection. The approach includes pollution prevention, continual environmental improvement, and supporting, as possible, community objectives (e.g., protection of the San Francisco Bay watershed).

Prediction of suspended-sediment concentrations at selected sites in the Fountain Creek watershed, Colorado, 2008-09

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Stogner, Sr., Robert W.; Nelson, Jonathan M.; McDonald, Richard R.; Kinzel, Paul J.; Mau, David P.

2013-01-01

In 2008, the U.S. Geological Survey (USGS), in cooperation with Pikes Peak Area Council of Governments, Colorado Water Conservation Board, Colorado Springs City Engineering, and the Lower Arkansas Valley Water Conservancy District, began a small-scale pilot study to evaluate the effectiveness of the use of a computational model of streamflow and suspended-sediment transport for predicting suspended-sediment concentrations and loads in the Fountain Creek watershed in Colorado. Increased erosion and sedimentation damage have been identified by the Fountain Creek Watershed Plan as key problems within the watershed. A recommendation in the Fountain Creek Watershed plan for management of the basin is to establish measurable criteria to determine if progress in reducing erosion and sedimentation damage is being made. The major objective of this study was to test a computational method to predict local suspended-sediment loads at two sites with different geomorphic characteristics in order to evaluate the feasibility of using such an approach to predict local suspended-sediment loads throughout the entire watershed. Detailed topographic surveys, particle-size data, and suspended-sediment samples were collected at two gaged sites: Monument Creek above Woodmen Road at Colorado Springs, Colorado (USGS gage 07103970), and Sand Creek above mouth at Colorado Springs, Colorado (USGS gage 07105600). These data were used to construct three-dimensional computational models of relatively short channel reaches at each site. The streamflow component of these models predicted a spatially distributed field of water-surface elevation, water velocity, and bed shear stress for a range of stream discharges. Using the model predictions, along with measured particle sizes, the sediment-transport component of the model predicted the suspended-sediment concentration throughout the reach of interest. These computed concentrations were used with predicted flow patterns and channel morphology to

The Distribution and Magnitude of Glacial Erosion on 103-year Timescales at Engabreen, Norway

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Rand, C.; Goehring, B. M.

2017-12-01

We derive the magnitudes of glacial erosion integrated over 103-year timescales across a transect transverse to the direction of ice flow at Engabreen, Norway. Understanding the distribution of glacial erosion is important for several reasons, including sediment budgeting to fjord environments, development of robust landscape evolution models, and if a better understanding between erosion and ice-bed interface properties (e.g., sliding rate, basal water pressure) can be developed, we can use records of glacial erosion to infer glaciological properties that can ultimately benefit models of past and future glaciers. With few exceptions, measurements of glacial erosion are limited to the historical past and even then are rare owing to the difficulty of accessing the glacier bed. One method proven useful in estimating glacial erosion on 103-year timescales is to measure the remaining concentrations of cosmogenic nuclides that accumulate in exposed bedrock during periods of retracted glacier extent and are removed by glacial erosion and radioactive decay during ice cover. Here we will present measurements of 14C and 10Be measured in proglacial bedrock from Engabreen. Our transects are ca. 600 and 400 meters in front of the modern ice front, and based on historical imagery, was ice covered until the recent past. Initial 10Be results show an increase in concentrations of nearly an order of magnitude from the samples near the center of the glacial trough to those on the lateral margin, consistent with conceptual models of glacial erosion parameterized in terms of sliding velocity. Naïve exposure ages that assume no subglacial erosion range from 0.22 - 9.04 ka. More importantly, we can estimate erosion depths by assuming zero erosion of the highest concentration sample along the two transects and calculate the amount of material removed to yield the lower concentrations elsewhere along the two transects. Results indicate minimum erosion depths of 1-183 cm for most ice

THE EVALUATION OF SOIL EROSION OFF-SITES EFFECTS IN LARGE BASINS: THE STUDYCASE OF LERMA-CHAPALA WATERSHED, MEXICO

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Helena Cotler A.

2005-05-01

Full Text Available One of the primary global concerns during the new millennium is the assessment of the impact of accelerated soil erosion on the economy and the environment (Pimentel et al. 1995; Lal, 1995. Erosion damages the site on which it occurs and also has undesirable effects off-site in the larger environment. Erosion moves sediments and nutrients out of the land, creating the two most widespread water pollution problems in the rivers, lakes and dams. The nutrients impact water quality largely through the process of eutrophication caused by an excessive content of nitrogen and phosphorus. In addition to the nutrients presence, sediment and runoff may also carry toxic metals and organic compounds, such as pesticides (Brady and Weil, 1999; Lal, 1994; de Graaf, 2000; Renschler and Harbor, 2002. The sediment itself is a major pollutant causative agent, causing a wide range of environmental damages. The sedimentation of dams and canals, reduces their lifetime and efficiency, promoting a high restoration cost to the downstream users and affecting thenational budget. In this sense, sedimentation knowledge is an important tool to guide spatial planning efficiently. Despite more than six decades of research, sedimentation is still probably the most serious technical problem faced by the dam industry (Mc Cully, 2001. Many studies estimate present-day fluvial sediment and solute loads including both natural and accelerated soil erosion (Douglas, 1990. However, as Douglas mentioned (op.cit many do not include all the erosion caused by human activity, because the eroded sediment is redeposited after a short movement downslope. Many soil particles are detached and carried downslope only to be held and trapped by a plant, tree or other obstacle a little further downslope. The sediment reaching the valley floor may not be completely removed by the river, but may be redistributed as alluvial floodplain deposits. The sediment transported downstream may be redeposited

Assessing Watershed-Wildfire Risks on National Forest System Lands in the Rocky Mountain Region of the United States

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Jessica R. Haas

2013-07-01

Full Text Available Wildfires can cause significant negative impacts to water quality with resultant consequences for the environment and human health and safety, as well as incurring substantial rehabilitation and water treatment costs. In this paper we will illustrate how state-of-the-art wildfire simulation modeling and geospatial risk assessment methods can be brought to bear to identify and prioritize at-risk watersheds for risk mitigation treatments, in both pre-fire and post-fire planning contexts. Risk assessment results can be particularly useful for prioritizing management of hazardous fuels to lessen the severity and likely impacts of future wildfires, where budgetary and other constraints limit the amount of area that can be treated. Specifically we generate spatially resolved estimates of wildfire likelihood and intensity, and couple that information with spatial data on watershed location and watershed erosion potential to quantify watershed exposure and risk. For a case study location we focus on National Forest System lands in the Rocky Mountain Region of the United States. The Region houses numerous watersheds that are critically important to drinking water supplies and that have been impacted or threatened by large wildfires in recent years. Assessment results are the culmination of a broader multi-year science-management partnership intended to have direct bearing on wildfire management decision processes in the Region. Our results suggest substantial variation in the exposure of and likely effects to highly valued watersheds throughout the Region, which carry significant implications for prioritization. In particular we identified the San Juan National Forest as having the highest concentration of at-risk highly valued watersheds, as well as the greatest amount of risk that can be mitigated via hazardous fuel reduction treatments. To conclude we describe future opportunities and challenges for management of wildfire-watershed interactions.

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

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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.

Gastro-oesophageal reflux is common in oligosymptomatic patients with dental erosion: A pH-impedance and endoscopic study.

Science.gov (United States)

Wilder-Smith, Clive H; Materna, Andrea; Martig, Lukas; Lussi, Adrian

2015-04-01

Dental erosion is a complication of gastro-oesophageal reflux disease (GORD) according to the Montreal consensus statement. However, GORD has not been comprehensively characterized in patients with dental erosions and pH-impedance measures have not been reported. Characterize GORD in patients with dental erosions using 24-h multichannel intraluminal pH-impedance measurements (pH-MII) and endoscopy. This single-centre study investigated reflux in successive patients presenting to dentists with dental erosion using pH-MII and endoscopy. Of the 374 patients, 298 (80%) reported GORD symptoms reflux episodes were 71 (63-79), 43 (38-49) and 31 (26-35), respectively. Of the reflux episodes, 19% (17-21) reached the proximal oesophagus. In 241 (69%) patients reflux was abnormal using published normal values for acid exposure time and reflux episodes. No significant associations between the severity of dental erosions and any reflux variables were found. The presence of GORD symptoms and of oesophagitis or a hiatal hernia was associated with greater reflux, but not with increased dental erosion scores. Significant oligosymptomatic gastro-oesophageal reflux occurs in the majority of patients with dental erosion. The degree of dental erosion did not correlate with any of the accepted quantitative reflux indicators. Definition of clinically relevant reflux parameters by pH-MII for dental erosion and of treatment guidelines are outstanding. Gastroenterologists and dentists need to be aware of the widely prevalent association between dental erosion and atypical GORD.

Usability and Functional Enhancements to an Online Interface for Predicting Post Fire Erosion (WEPP-PEP)

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Lew, Roger; Dobre, Mariana; Elliot, William; Robichaud, Pete; Brooks, Erin; Frankenberger, Jim

2017-04-01

There is an increased interest in the United States to use soil burn severity maps in watershed-scale hydrologic models to estimate post-fire sediment erosion from burned areas. This information is needed by stakeholders in order to concentrate their pre- or post-fire management efforts in ecologically sensitive areas to decrease the probability of post-fire sediment delivery. But these tools traditionally have been time consuming and difficult to use by managers because input datasets must be obtained and correctly processed for valid results. The Water Erosion Prediction Project (WEPP) has previously been developed as an online and easy-to-use interface to help land managers with running simulations without any knowledge of computer programming or hydrologic modeling. The interface automates the acquisition of DEM, climate, soils, and landcover data, and also automates channel and hillslope delineation for the users. The backend is built with Mapserver, GDAL, PHP, C++, Python while the front end uses OpenLayers, and, of course, JavaScript. The existing WEPP online interface was enhanced to provide better usability to stakeholders in United States (Forest Service, BLM, USDA) as well as to provide enhanced functionality for managing both pre-fire and post-fire treatments. Previously, only site administrators could add burn severity maps. The interface now allows users to create accounts to upload and share FlamMap prediction maps, differenced Normalized Burned Ratio (dNBR), or Burned Area Reflectance Classification (BARC) maps. All maps are loaded into a sortable catalog so users can quickly find their area of interest. Once loaded, the interface has been modified to support running comparisons between baseline condition with "no burn" and with a burn severity classification map. The interface has also been enhanced to allow users to conduct single storm analyses to examine, for example, how much soil loss would result after a 100-year storm. An OpenLayers map

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

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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.

Use of cesium-137 methodology in the evaluation of superficial erosive processes

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Avacir Casanova Andrello

2003-06-01

Full Text Available Superficial erosion is one of the main soil degradation agents and erosion rates estimations for different edaphicclimate conditions for the conventional models, as USLE and RUSLE, are expensive and time-consuming. The use of cesium-137 antrophogenic radionuclide is a new methodology that has been much studied and its application in the erosion soil evaluation has grown in countries as USA, UK, Australia and others. A brief narration of this methodology is being presented, as the development of the equations utilized for the erosion rates quantification through the cesium-137 measurements. Two watersheds studied in Brazil have shown that the cesium-137 methodology was practicable and coherent with the survey in field for applications in erosion studies.A erosão superficial é um dos principais agentes de degradação dos solos e estimativas das taxas de erosão para diferentes condições edafoclimáticas pelos modelos tradicionais como USLE, RUSLE, são onerosos e demorados. Uma metodologia que tem sido muito estudada e sua aplicação no estudo da erosão vem crescendo em países como EUA, Reino Unido, Austrália, e outros, é a do uso do radionuclídeo antropogênico césio-137. Um resumo da história desta metodologia é apresentado, assim como a evolução das equações utilizadas para quantificar as taxas de erosão através da medida do césio-137. Duas bacias estudadas no Brasil mostraram que a metodologia do césio-137 é viável e coerente com as observações em campo para aplicação no estudo da erosão.

The role of forest stand density in controlling soil erosion: implications to sediment-related disasters in Japan.

Science.gov (United States)

Razafindrabe, Bam H N; He, Bin; Inoue, Shoji; Ezaki, Tsugio; Shaw, Rajib

2010-01-01

The role of forest stand density in controlling soil erosion was investigated in Ehime Prefecture, Japan. The main objective was to compare soil erosion under different forest conditions including forest type, species composition, and stand density as influenced by thinning operations. Relative yield index (Ry) was used as an indicator of stand density to reflect the degree of management operations in the watershed. Eleven treatments were established based on the above forest conditions. Soil loss was collected in each of the 11 treatments after each rainfall event for a period of 1 year. The paper presents summary data on soil loss as affected by forest conditions and rainfall patterns. Findings showed that an appropriate forest management operation, which can be insured by stand density control, is needed to reduce soil loss. The present study plays an important role in clarifying technical processes related to soil erosion, while it helps linking these elements to current Japanese forestry issues and bringing new inputs to reducing sediment-related disasters in Japan.

Application of the Water Erosion Prediction Project (WEPP) Model to simulate streamflow in a PNW forest watershed

Science.gov (United States)

A. Srivastava; M. Dobre; E. Bruner; W. J. Elliot; I. S. Miller; J. Q. Wu

2011-01-01

Assessment of water yields from watersheds into streams and rivers is critical to managing water supply and supporting aquatic life. Surface runoff typically contributes the most to peak discharge of a hydrograph while subsurface flow dominates the falling limb of hydrograph and baseflow contributes to streamflow from shallow unconfined aquifers primarily during the...

Management-oriented sensitivity analysis for pesticide transport in watershed-scale water quality modeling using SWAT.

Science.gov (United States)

Luo, Yuzhou; Zhang, Minghua

2009-12-01

The Soil and Water Assessment Tool (SWAT) was calibrated for hydrology conditions in an agricultural watershed of Orestimba Creek, California, and applied to simulate fate and transport of two organophosphate pesticides chlorpyrifos and diazinon. The model showed capability in evaluating pesticide fate and transport processes in agricultural fields and instream network. Management-oriented sensitivity analysis was conducted by applied stochastic SWAT simulations for pesticide distribution. Results of sensitivity analysis identified the governing processes in pesticide outputs as surface runoff, soil erosion, and sedimentation in the study area. By incorporating sensitive parameters in pesticide transport simulation, effects of structural best management practices (BMPs) in improving surface water quality were demonstrated by SWAT modeling. This study also recommends conservation practices designed to reduce field yield and in-stream transport capacity of sediment, such as filter strip, grassed waterway, crop residue management, and tailwater pond to be implemented in the Orestimba Creek watershed.

Use RUSLE2 model to assess the impact of soil erosion on playa inundation and hydrophyte conditions in the Rainwater Basin, Nebraska.

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Tang, Zhenghong; Gu, Yue; Jiang, Weiguo; Xue, Yuan; Bishop, Andy; LaGrange, Ted; Nugent, Eleanor

2016-06-01

Playas in the Rainwater Basin region in Nebraska are globally important wetlands that are continuously threatened by culturally accelerated sedimentation. Using annual habitat survey data and wetland vegetation inventories, inundation and hydrophyte community distributions were evaluated for properties under different types of conservation status. Annual soil erosion rates from surrounding watersheds were calculated to estimate sediment accumulated rates using the Revised Universal Soil Loss Equation 2 (RUSLE2). The slope-length component of the RUSLE2 was derived from 2009 light detection and ranging (LiDAR) data after the methods described by Van Remortel (Computers & Geosciences 30:1043-1053, 2004). Wetlands enrolled in conservation programs were inundated more and were dominated to a greater degree by hydrophytes than wetlands not enrolled in these programs. The mean estimated soil erosion rate at the Rainwater Basin landscape level was 4.67 tons/ha/year, and the mean estimated sediment accumulation depth for public watersheds was estimated as 0.19 cm/year. Without appropriate conservation actions, the current inundated acres and wetland acres growing hydrophytes would be further reduced by sediment accumulation. The results illustrated the importance of conservation programs to protect wetlands.

Evaluating Hydrologic Response of an Agricultural Watershed for Watershed Analysis

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Manoj Kumar Jha

2011-06-01

Full Text Available This paper describes the hydrological assessment of an agricultural watershed in the Midwestern United States through the use of a watershed scale hydrologic model. The Soil and Water Assessment Tool (SWAT model was applied to the Maquoketa River watershed, located in northeast Iowa, draining an agriculture intensive area of about 5,000 km2. The inputs to the model were obtained from the Environmental Protection Agency’s geographic information/database system called Better Assessment Science Integrating Point and Nonpoint Sources (BASINS. Meteorological input, including precipitation and temperature from six weather stations located in and around the watershed, and measured streamflow data at the watershed outlet, were used in the simulation. A sensitivity analysis was performed using an influence coefficient method to evaluate surface runoff and baseflow variations in response to changes in model input hydrologic parameters. The curve number, evaporation compensation factor, and soil available water capacity were found to be the most sensitive parameters among eight selected parameters. Model calibration, facilitated by the sensitivity analysis, was performed for the period 1988 through 1993, and validation was performed for 1982 through 1987. The model was found to explain at least 86% and 69% of the variability in the measured streamflow data for calibration and validation periods, respectively. This initial hydrologic assessment will facilitate future modeling applications using SWAT to the Maquoketa River watershed for various watershed analyses, including watershed assessment for water quality management, such as total maximum daily loads, impacts of land use and climate change, and impacts of alternate management practices.

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

Turbidity on the Shallow Reef off Kaulana and Hakioawa Watersheds, North Coast of Kaho`olawe, Hawai`iMeasurements of Turbidity and Ancillary Data on Winds, Waves, Precipitation, and Stream flow Discharge, November 2005 to June 2008

Science.gov (United States)

Presto, M. Katherine; Storlazzi, Curt D.; Field, Michael E.; Abbott, Lyman L.

2010-01-01

The island of Kaho`olawe has particular cultural and religious significance for native Hawaiians. Once known as Kanaloa, the island was a center for native Hawaiian navigation. In the mid-20th century, the island was used as a bombing range by the U.S. Navy, and that practice, along with the foraging by feral goats, led to a near-complete decimation of vegetation. The loss of ground cover led to greatly increased erosion and run-off of sediment-laden water onto the island's adjacent coral reefs. Litigation in 1990 ended the U.S. Navy's use of the island as a bombing range, and in 1994 the island was transferred to the Kaho`olawe Island Reserve Commission (KIRC), http://kahoolawe.hawaii.gov/. As a result of the litigation, the U.S. Navy began a 10-year clean-up effort that was the foundation for the present restoration effort by KIRC (Slay, 2009). The restoration effort is centered on revegetating the island, reducing erosion, and limiting run-off onto adjacent reefs. Restoration efforts to mitigate sediment runoff to streams and gulches by restoring native vegetation and minimizing erosion have focused on two watersheds, Kaulana and Hakioawa, on the northeast and northwest sides of the island, respectively. Stream flow and sediment gages were installed by the U.S. Geological Survey Pacific Islands Water Science Center in each of the watersheds, and a weather station was established upland of the watersheds. For this study, turbidity monitors were installed on the insular shelf off the two watersheds to monitor the overall quality of reef waters and their changes in response to rain and stream flow discharge events.

Preliminary assessment of soil erosion impact during forest restoration process

Science.gov (United States)

Lai, Yen-Jen; Chang, Cheng-Sheng; Tsao, Tsung-Ming; Wey, Tsong-Huei; Chiang, Po-Neng; Wang, Ya-Nan

2014-05-01

Taiwan has a fragile geology and steep terrain. The 921 earthquake, Typhoon Toraji, Typhoon Morakot, and the exploitation and use of the woodland by local residents have severely damaged the landscape and posed more severe challenges to the montane ecosystem. A land conservation project has been implemented by the Experimental Forest of National Taiwan University which reclaimed approximately 1,500 hectares of leased woodland from 2008 to 2010, primarily used to grow bamboo, tea trees, betel nut, fruit, and vegetable and about 1,298 hectares have been reforested. The process of forest restoration involves clear cutting, soil preparation and a six-year weeding and tending period which may affect the amount of soil erosion dramatically. This study tried to assess the impact of forest restoration from the perspective of soil erosion through leased-land recovery periods and would like to benefit the practical implementation of reforestation in the future. A new plantation reforested in the early 2013 and a nearby 29-year-old mature forest were chosen as experimental and comparison sites. A self-designed weir was set up in a small watershed of each site for the runoff and sediment yield observation. According to the observed results from May to August 2013, a raining season in Taiwan, the runoff and erosion would not as high as we expected, because the in-situ soil texture of both sites is sandy loam to sandy with high percentage of coarse fragment which increased the infiltration. There were around 200 kg to 250 kg of wet sand/soil yielded in mature forest during the hit of Typhoon Soulik while the rest of the time only suspended material be yielded at both sites. To further investigate the influence of the six-year weeding and tending period, long term observations are needed for a more completed assessment of soil erosion impact.

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.

Assessing the effects of regional payment for watershed services program on water quality using an intervention analysis model.

Science.gov (United States)

Lu, Yan; He, Tian

2014-09-15

Much attention has been recently paid to ex-post assessments of socioeconomic and environmental benefits of payment for ecosystem services (PES) programs on poverty reduction, water quality, and forest protection. To evaluate the effects of a regional PES program on water quality, we selected chemical oxygen demand (COD) and ammonia-nitrogen (NH3-N) as indicators of water quality. Statistical methods and an intervention analysis model were employed to assess whether the PES program produced substantial changes in water quality at 10 water-quality sampling stations in the Shaying River watershed, China during 2006-2011. Statistical results from paired-sample t-tests and box plots of COD and NH3-N concentrations at the 10 stations showed that the PES program has played a positive role in improving water quality and reducing trans-boundary water pollution in the Shaying River watershed. Using the intervention analysis model, we quantitatively evaluated the effects of the intervention policy, i.e., the watershed PES program, on water quality at the 10 stations. The results suggest that this method could be used to assess the environmental benefits of watershed or water-related PES programs, such as improvements in water quality, seasonal flow regulation, erosion and sedimentation, and aquatic habitat. Copyright © 2014 Elsevier B.V. All rights reserved.

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...

Spatial patterns of soil nutrients and groundwater levels within the Debre Mawi watershed of the Ethiopian highlands

Science.gov (United States)

Guzman, Christian; Tilahun, Seifu; Dagnew, Dessalegn; Zegeye, Assefe; Tebebu, Tigist; Yitaferu, Birru; Steenhuis, Tammo

2015-04-01

Persistent patterns of erosion have emerged in the Ethiopian highlands leading to soil and water conservation practices being implemented throughout the countryside. A common concern is the loss of soil fertility and loss of soil water. This study investigates the spatial patterns of soil nutrients and water table depths in a small sub-watershed in the northwestern Ethiopian highlands. NPK, a particularly important group of nutrients for inorganic fertilizer considerations, did not follow a consistent trend as a group along and across slope and land use transects. Whereas nitrogen content was greatest in the upslope regions (~0.1% TN), available phosphorus had comparably similar content in the different slope regions throughout the watershed (~2.7 mg/kg). The exchangeable cations (K, Ca, Mg) did increase in content in a downslope direction (in most cases though, they were highest in the middle region) but not consistently later in the season. On average, calcium (40 cmol/kg), magnesium (5 cmol/kg), and potassium (0.5 cmol/kg) were orders of magnitudes different in content. The perched water table in different areas of the watershed showed a very distinct trend. The lower part of the sub-watershed had shallower levels of water table depths (less than 10 cm from the surface) than did the upper parts of the sub-watershed (usually greater than 120 cm from the surface). The middle part of the sub-watershed had water table depths located at 40 to 70 cm below the surface. These results show how the landscape slope position and land use may be important for planning where and when soil nutrients and water would be expected to be appropriately "conserved" or stored.

Simulation of soil loss processes based on rainfall runoff and the time factor of governance in the Jialing River Watershed, China.

Science.gov (United States)

Wu, Lei; Long, Tian-Yu; Liu, Xia; Mmereki, Daniel

2012-06-01

Jialing River is the largest tributary in the catchment area of Three Gorges Reservoir, and it is also one of the important areas of sediment yield in the upper reaches of the Yangtze River. In recent years, significant changes of water and sediment characteristics have taken place. The "Long Control" Project implemented since 1989 had greatly changed the surface appearance of the Jialing River Watershed (JRW), and it had made the environments of the watershed sediment yield and sediment transport change significantly. In this research, the Revised Universal Soil Loss Equation was selected and used to predict the annual average amount of soil erosion for the special water and sediment environments in the JRW after the implementation of the "Long Control" Project, and then the rainfall-runoff modulus and the time factor of governance were both considered as dynamic factors, the dynamic sediment transport model was built for soil erosion monitoring and forecasting based on the average sediment yield model. According to the dynamic model, the spatial and temporal distribution of soil erosion amount and sediment transport amount of the JRW from 1990 to 2007 was simulated using geographic information system (GIS) technology and space-grid algorithm. Simulation results showed that the average relative error of sediment transport was less than 10% except for the extreme hydrological year. The relationship between water and sediment from 1990 to 2007 showed that sediment interception effects of the soil and water conservation projects were obvious: the annual average sediment discharge reduced from 145.3 to 35 million tons, the decrement of sediment amount was about 111 million tons, and decreasing amplitude was 76%; the sediment concentration was also decreased from 2.01 to 0.578 kg/m(3). These data are of great significance for the prediction and estimation of the future changing trends of sediment storage in the Three Gorges Reservoir and the particulate non

Water Erosion Distribution in the Itutinga/Camargos Hydroelectric Plant Watershed (Minas Gerais, Brazil) using Distributed Modeling

Science.gov (United States)

Mapping and assessment of erosion risk is an important tool for planning of natural resources management, allowing researchers to modify land-use properly and implement management strategies more sustainable in the long-term. The Grande River Basin (GRB), located in Minas Gerais State, is one of the...

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.

A Stochastic Multi-Media Model of Microbial Transport in Watersheds

Science.gov (United States)

Yeghiazarian, L.; Safwat, A.; Whiteaker, T.; Teklitz, A.; Nietch, C.; Maidment, D. R.; Best, E. P.

2012-12-01

Fecal contamination is the leading cause of surface-water impairment in the US, and fecal pathogens are capable of triggering massive outbreaks of gastrointestinal disease. The difficulty in prediction of water contamination has its roots in the stochastic variability of fecal pathogens in the environment, and in the complexity of microbial dynamics and interactions on the soil surface and in water. To address these challenges, we have developed a stochastic model whereby the transport of microorganisms in watersheds is considered in two broad categories: microorganisms that are attached to mineral or organic substrates in suspended sediment; and unattached microorganisms suspended in overland flow. The interactions of microorganisms with soil particles on the soil surface and in the overland flow lead to transitions of microorganisms between solid and aqueous media. The strength of attachment of microorganisms to soil particles is determined by the chemical characteristics of soils which are highly correlated with the particle size. The particle size class distribution in the suspended sediment is predicted by the Water Erosion Prediction Project (WEPP). The model is integrated with ArcGIS, resulting in a general transport-modeling framework applicable to a variety of biological and chemical surface water contaminants. Simulations are carried out for a case study of contaminant transport in the East Fork Little Miami River Watershed in Ohio. Model results include the spatial probability distribution of microbes in the watershed and can be used for assessment of (1) mechanisms dominating microbial transport, and (2) time and location of highest likelihood of microbial occurrence, thus yielding information on best water sampling strategies.

Gastro-oesophageal reflux is common in oligosymptomatic patients with dental erosion: A pH-impedance and endoscopic study

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Materna, Andrea; Martig, Lukas; Lussi, Adrian

2015-01-01

Background Dental erosion is a complication of gastro-oesophageal reflux disease (GORD) according to the Montreal consensus statement. However, GORD has not been comprehensively characterized in patients with dental erosions and pH-impedance measures have not been reported. Objectives Characterize GORD in patients with dental erosions using 24-h multichannel intraluminal pH-impedance measurements (pH-MII) and endoscopy. Methods This single-centre study investigated reflux in successive patients presenting to dentists with dental erosion using pH-MII and endoscopy. Results Of the 374 patients, 298 (80%) reported GORD symptoms reflux episodes were 71 (63–79), 43 (38–49) and 31 (26–35), respectively. Of the reflux episodes, 19% (17–21) reached the proximal oesophagus. In 241 (69%) patients reflux was abnormal using published normal values for acid exposure time and reflux episodes. No significant associations between the severity of dental erosions and any reflux variables were found. The presence of GORD symptoms and of oesophagitis or a hiatal hernia was associated with greater reflux, but not with increased dental erosion scores. Conclusions Significant oligosymptomatic gastro-oesophageal reflux occurs in the majority of patients with dental erosion. The degree of dental erosion did not correlate with any of the accepted quantitative reflux indicators. Definition of clinically relevant reflux parameters by pH-MII for dental erosion and of treatment guidelines are outstanding. Gastroenterologists and dentists need to be aware of the widely prevalent association between dental erosion and atypical GORD. PMID:25922678

Using 137Cs as a tool for the assessment and the management of erosion/sedimentation risks in view of the restoration of the Rainbow Smelt (Osmerus mordax) fish population in the Boyer River basin (Quebec, Canada)

International Nuclear Information System (INIS)

Bernard, C.; Laverdiere, M.R.

2000-01-01

The Boyer River (Quebec, Canada) drains a 217 km 2 watershed that is under cultivation at 60%. The last 2 km of the river bed has always been used as a spawning ground by Rainbow Smelts (Osmerus mordax). This fish population, which plays an important ecological role in the St. Lawrence River estuary, has dramatically declined over the last decades. Siltation and excessive algal growth in the spawning area were identified as the most probable causes of the fish population decline; suggesting that soil erosion, nutrient and sediment transport are major factors underlying the environmental problem. In this context, 137 Cs provides an effective tool for investigating the magnitude and spatial distribution of long-term soil redistribution taking place in the watershed. Sampling of cultivated fields, riverbanks, bottom sediments and forested sites were thus undertaken to help understand the erosive behaviour of the watershed. Results obtained so far suggest in-field erosion rates of up to 13 t ha -1 yr -1 with net outputs reaching 11 t ha -1 yr -1 . These results agree well with estimates obtained from the USLE. The 137 Cs data indicate that fields located in the upstream half of the basin produce smaller sediment loadings than those in the downstream portion, despite higher soil erodibilities and more frequent use for annual crops. They also suggest that more than 75% of the sediment deposited in the spawning area originates from cultivated fields, and less than 25% from streambanks. (author)

Watershed assessment-watershed analysis: What are the limits and what must be considered

Science.gov (United States)

Robert R. Ziemer

2000-01-01

Watershed assessment or watershed analysis describes processes and interactions that influence ecosystems and resources in a watershed. Objectives and methods differ because issues and opportunities differ.

Application of Watershed Scale Models to Predict Nitrogen Loading From Coastal Plain Watersheds

Science.gov (United States)

George M. Chescheir; Glenn P Fernandez; R. Wayne Skaggs; Devendra M. Amatya

2004-01-01

DRAINMOD-based watershed models have been developed and tested using data collected from an intensively instrumented research site on Kendricks Creek watershed near Plymouth. NC. These models were applied to simulate the hydrology and nitrate nitrogen (NO3-N) loading from two other watersheds in the Coastal Plain of North Carolina, the 11600 ha Chicod Creek watershed...

Hydrological services and biodiversity conservation under forestation scenarios: comparing options to improve watershed management

Science.gov (United States)

Carvalho-Santos, Claudia; Nunes, João Pedro; Sousa-Silva, Rita; Gonçalves, João; Pradinho Honrado, João

2015-04-01

Humans rely on ecosystems for the provision of hydrological services, namely water supply and water damage mitigation, and promoting forests is a widely used management strategy for the provision of hydrological services. Therefore, it is important to model how forests will contribute for this provision, taking into account the environmental characteristics of each region, as well as the spatio-temporal patterns of societal demand. In addition, ensuring forest protection and the delivery of forest ecosystem services is one of the aims included in the European Union biodiversity strategy to 2020. On the other hand, forest management for hydrological services must consider possible trade-offs with other services provision, as well as with biodiversity conservation. Accurate modeling and mapping of both hydrological services and biodiversity conservation value is thus important to support spatial planning and land management options involving forests. The objectives of this study were: to analyze the provision and spatial dynamics of hydrological services under two forest cover change scenarios (oak and eucalyptus/pine) compared to the current shrubland-dominated landscape; and to evaluate their spatial trade-offs with biodiversity conservation value. The Vez watershed (250km2), in northwest Portugal, was used as case-study area. SWAT (Soil and Water Assessment Tool) was applied to simulate the provision of hydrological services (water supply quantity, timing and quality; soil erosion and flood regulation), and was calibrated against daily discharge, sediments, nitrates and evapotranspiration. Good agreement was obtained between model predictions and field measurements. The maps for each service under the different scenarios were produced at the Hydrologic Response Unit (HRU) level. Biodiversity conservation value was based on nature protection regimes and on expert valuation applied to a land cover map. Statistical correlations between hydrological services provision

Prioritization of watersheds in order to perform administrative measures using fuzzy analytic hierarchy process

Directory of Open Access Journals (Sweden)

Seyyed Abdolhossein Arami

2017-01-01

Full Text Available Prioritization of watersheds in order to perform administrative measures is necessary and inevitable. Determining areas of top priority for flood control projects is a managerial decision that should be approved by studies of physical, social and economic status of the region of interesrt and by assessing the outcomes of the past operations. Therefore, the aim of this research was to study morphological and physiographic characteristics, and to use geographic information systems (GIS and multi-criteria decision-making methods (MCDM, to identify the critical sub-basins which have the tendency to be destructed, in Galikesh watershed, Golestan province. This watershed is important, yet critical, in terms of land use change, erosion and flooding in the Golestan Province, Iran. In total, nine morphological parameters were used to prioritize sub-watersheds using fuzzy analytic hierarchy process (FAHP. The morphological parameters were by some means linked to watershed drainage system. Based on FAHP approach, sub-basins, as vulnerable zones, have been evaluated and cetegorized in five priority levels (very low, low, medium, high and very high levels. The results showed that 44.44% and 22.22% of sub-basins were categorized respectively under average, and high to very high levels, suggesting that the conservation and management measures are essential in order to maintain stability in the region. Thus, the FAHP technique is a practical and convenient method to show potential zones in order to implement effective management strategies, especially in areas where data availability is low and soil diversity is high. Finally, it can be said that without having to encounter high costs and a waste of time, sub-basins could be categorized by means of morphometric parameters in order to implement conservational measures to simutaneously conserve soil and the environment

Land suitability assessment on a watershed of Loess Plateau using the analytic hierarchy process.

Science.gov (United States)

Yi, Xiaobo; Wang, Li

2013-01-01

In order to reduce soil erosion and desertification, the Sloping Land Conversion Program has been conducted in China for more than 15 years, and large areas of farmland have been converted to forest and grassland. However, this large-scale vegetation-restoration project has faced some key problems (e.g. soil drying) that have limited the successful development of the current ecological-recovery policy. Therefore, it is necessary to know about the land use, vegetation, and soil, and their inter-relationships in order to identify the suitability of vegetation restoration. This study was conducted at the watershed level in the ecologically vulnerable region of the Loess Plateau, to evaluate the land suitability using the analytic hierarchy process (AHP). The results showed that (1) the area unsuitable for crops accounted for 73.3% of the watershed, and the main factors restricting cropland development were soil physical properties and soil nutrients; (2) the area suitable for grassland was about 86.7% of the watershed, with the remaining 13.3% being unsuitable; (3) an area of 3.95 km(2), accounting for 66.7% of the watershed, was unsuitable for forest. Overall, the grassland was found to be the most suitable land-use to support the aims of the Sloping Land Conversion Program in the Liudaogou watershed. Under the constraints of soil water shortage and nutrient deficits, crops and forests were considered to be inappropriate land uses in the study area, especially on sloping land. When selecting species for re-vegetation, non-native grass species with high water requirements should be avoided so as to guarantee the sustainable development of grassland and effective ecological functioning. Our study provides local land managers and farmers with valuable information about the inappropriateness of growing trees in the study area along with some information on species selection for planting in the semi-arid area of the Loess Plateau.

Hydraulic characteristics and sediment generation on slope erosion in the Three Gorges Reservoir Area, China

Directory of Open Access Journals (Sweden)

Qian Feng

2016-09-01

Full Text Available Hydrological processes play important roles in soil erosion processes of the hillslopes. This study was conducted to investigate the hydrological processes and the associated erosional responses on the purple soil slope. Based on a comprehensive survey of the Wangjiaqiao watershed in the Three Gorges Reservoir, four typical slope gradients (5°, 10°, 15°and 20° were applied to five rainfall intensities (0.6, 1.1, 1.61, 2.12 and 2.54 mm·min-1. The results showed that both surface and subsurface runoff varied greatly depending on the rainfall intensity and slope gradient. Surface runoff volume was 48.1 to 280.1 times of that for subsurface runoff. The critical slope gradient was about 10°. The sediment yield rate increased with increases in both rainfall intensity and slope gradient, while the effect of rainfall intensity on the sediment yield rate was greater than slope gradient. There was a good linear relationship between sediment yield rate and Reynolds numbers, flow velocity and stream power, while Froude numbers, Darcy-Weisbach and Manning friction coefficients were not good hydraulic indicators of the sediment yield rate of purple soil erosion. Among the three good indicators (Re, v and w, stream power was the best predictor of sediment yield rate (R2 = 0.884. Finally, based on the power regression relationship between sediment yield rate, runoff rate, slope gradient and rainfall intensity, an erosion model was proposed to predict the purple soil erosion (R2 = 0.897. The results can help us to understand the relationship between flow hydraulics and sediment generation of slope erosion and offer useful data for the building of erosion model in purple soil.

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

Soil erosion is one of the most significant environmental problems in China. From 2010 to 2012, the fourth national census for soil erosion sampled 32 364 PSUs (Primary Sampling Units, small watersheds) with the areas of 0.2-3 km2. Land use and soil erosion controlling factors including rainfall erosivity, soil erodibility, slope length, slope steepness, biological practice, engineering practice, and tillage practice for the PSUs were surveyed, and the soil loss rate for each land use in the PSUs was estimated using an empirical model, the Chinese Soil Loss Equation (CSLE). Though the information collected from the sample units can be aggregated to estimate soil erosion conditions on a large scale; the problem of estimating soil erosion condition on a regional scale has not been addressed well. The aim of this study is to introduce a new model-based regional soil erosion assessment method combining a sample survey and geostatistics. We compared seven spatial interpolation models based on the bivariate penalized spline over triangulation (BPST) method to generate a regional soil erosion assessment from the PSUs. Shaanxi Province (3116 PSUs) in China was selected for the comparison and assessment as it is one of the areas with the most serious erosion problem. Ten-fold cross-validation based on the PSU data showed the model assisted by the land use, rainfall erosivity factor (R), soil erodibility factor (K), slope steepness factor (S), and slope length factor (L) derived from a 1 : 10 000 topography map is the best one, with the model efficiency coefficient (ME) being 0.75 and the MSE being 55.8 % of that for the model assisted by the land use alone. Among four erosion factors as the covariates, the S factor contributed the most information, followed by K and L factors, and R factor made almost no contribution to the spatial estimation of soil loss. The LS factor derived from 30 or 90 m Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) data

Management-oriented sensitivity analysis for pesticide transport in watershed-scale water quality modeling using SWAT

International Nuclear Information System (INIS)

Luo Yuzhou; Zhang Minghua

2009-01-01

The Soil and Water Assessment Tool (SWAT) was calibrated for hydrology conditions in an agricultural watershed of Orestimba Creek, California, and applied to simulate fate and transport of two organophosphate pesticides chlorpyrifos and diazinon. The model showed capability in evaluating pesticide fate and transport processes in agricultural fields and instream network. Management-oriented sensitivity analysis was conducted by applied stochastic SWAT simulations for pesticide distribution. Results of sensitivity analysis identified the governing processes in pesticide outputs as surface runoff, soil erosion, and sedimentation in the study area. By incorporating sensitive parameters in pesticide transport simulation, effects of structural best management practices (BMPs) in improving surface water quality were demonstrated by SWAT modeling. This study also recommends conservation practices designed to reduce field yield and in-stream transport capacity of sediment, such as filter strip, grassed waterway, crop residue management, and tailwater pond to be implemented in the Orestimba Creek watershed. - Selected structural BMPs are recommended for reducing loads of OP pesticides.

Management-oriented sensitivity analysis for pesticide transport in watershed-scale water quality modeling using SWAT

Energy Technology Data Exchange (ETDEWEB)

Luo Yuzhou [University of California, Davis, CA 95616 (United States); Wenzhou Medical College, Wenzhou 325035 (China); Zhang Minghua, E-mail: mhzhang@ucdavis.ed [University of California, Davis, CA 95616 (United States); Wenzhou Medical College, Wenzhou 325035 (China)

2009-12-15

The Soil and Water Assessment Tool (SWAT) was calibrated for hydrology conditions in an agricultural watershed of Orestimba Creek, California, and applied to simulate fate and transport of two organophosphate pesticides chlorpyrifos and diazinon. The model showed capability in evaluating pesticide fate and transport processes in agricultural fields and instream network. Management-oriented sensitivity analysis was conducted by applied stochastic SWAT simulations for pesticide distribution. Results of sensitivity analysis identified the governing processes in pesticide outputs as surface runoff, soil erosion, and sedimentation in the study area. By incorporating sensitive parameters in pesticide transport simulation, effects of structural best management practices (BMPs) in improving surface water quality were demonstrated by SWAT modeling. This study also recommends conservation practices designed to reduce field yield and in-stream transport capacity of sediment, such as filter strip, grassed waterway, crop residue management, and tailwater pond to be implemented in the Orestimba Creek watershed. - Selected structural BMPs are recommended for reducing loads of OP pesticides.

USDA-ARS Southeast Watershed Laboratory at Tifton, GA:Index Site Design for the Suwannee Basin

Science.gov (United States)

Bosch, D.; Strickland, T.; Sheridan, J.; Lowrance, R.; Truman, C.; Hubbard, R.; Potter, T.; Wauchope, D.; Vellidis, G.; Thomas, D.

2001-12-01

The Southeast Watershed Hydrology Research Center (SEWHRC) was established in 1966 by order of the U.S. Senate "to identify and characterize those elements that control the flow of water from watersheds in the southeast". A 129 sq.mi. area within the headwaters of Little River Watershed (LRW) in central south Georgia was instrumented to provide data for evaluating and characterizing Coastal Plain hydrologic processes and for development and testing of prediction methodologies for use in ungaged watersheds in regions of low topographic relief. Pesticide analytical capabilities were added in 1976, and inorganic chemistry and sediment transport research were expanded. In 1980, the Center was renamed as the Southeast Watershed Research Laboratory (SEWRL), and laboratories were constructed for nutrient analysis and soil physics. A pesticide analysis laboratory was constructed in 1987. In the early 1990s, a hydraulics laboratory was established for sediment and chemical transport studies, and research on riparian buffers was expanded. The SEWRL research program continues to focus on hydrologic and environmental concerns. Major components of the program are hydrology, pesticides behavior, buffer systems, animal waste management, erosion, remote sensing of watershed condition, and relationships between site-specific agricultural management (BMPs) and small-to-large watershed response. SEWRL's program will be expanded over the next five years to include two additional watersheds comparable in size and instrumentation to the LRW; nesting the LRW within the full Little River drainage and subsequently...all three watersheds within the full Suwannee Basin; and mapping and quantifying irrigation water removals within the Suwannee Basin. We will instrument the three intensive study watersheds and the full Suwannee Basin to provide real-time characterization of precipitation, soil moisture, hydrologic flow, and water quality at a range of spatial and temporal scales. We will

A coupled model approach to reduce nonpoint-source pollution resulting from predicted urban growth: A case study in the Ambos Nogales watershed

Science.gov (United States)

Norman, L.M.; Guertin, D.P.; Feller, M.

2008-01-01

The development of new approaches for understanding processes of urban development and their environmental effects, as well as strategies for sustainable management, is essential in expanding metropolitan areas. This study illustrates the potential of linking urban growth and watershed models to identify problem areas and support long-term watershed planning. Sediment is a primary source of nonpoint-source pollution in surface waters. In urban areas, sediment is intermingled with other surface debris in transport. In an effort to forecast the effects of development on surface-water quality, changes predicted in urban areas by the SLEUTH urban growth model were applied in the context of erosion-sedimentation models (Universal Soil Loss Equation and Spatially Explicit Delivery Models). The models are used to simulate the effect of excluding hot-spot areas of erosion and sedimentation from future urban growth and to predict the impacts of alternative erosion-control scenarios. Ambos Nogales, meaning 'both Nogaleses,' is a name commonly used for the twin border cities of Nogales, Arizona and Nogales, Sonora, Mexico. The Ambos Nogales watershed has experienced a decrease in water quality as a result of urban development in the twin-city area. Population growth rates in Ambos Nogales are high and the resources set in place to accommodate the rapid population influx will soon become overburdened. Because of its remote location and binational governance, monitoring and planning across the border is compromised. One scenario described in this research portrays an improvement in water quality through the identification of high-risk areas using models that simulate their protection from development and replanting with native grasses, while permitting the predicted and inevitable growth elsewhere. This is meant to add to the body of knowledge about forecasting the impact potential of urbanization on sediment delivery to streams for sustainable development, which can be

Evaluating Hydrologic Response of an Agricultural Watershed for Watershed Analysis

OpenAIRE

Manoj Kumar Jha

2011-01-01

This paper describes the hydrological assessment of an agricultural watershed in the Midwestern United States through the use of a watershed scale hydrologic model. The Soil and Water Assessment Tool (SWAT) model was applied to the Maquoketa River watershed, located in northeast Iowa, draining an agriculture intensive area of about 5,000 km2. The inputs to the model were obtained from the Environmental Protection Agency’s geographic information/database system called Better Assessment Science...

Engaging Watershed Stakeholders for Cost-Effective Environmental Management Planning with "Watershed Manager"

Science.gov (United States)

Williams, Jeffery R.; Smith, Craig M.; Roe, Josh D.; Leatherman, John C.; Wilson, Robert M.

2012-01-01

"Watershed Manager" is a spreadsheet-based model that is used in extension education programs for learning about and selecting cost-effective watershed management practices to reduce soil, nitrogen, and phosphorus losses from cropland. It can facilitate Watershed Restoration and Protection Strategy (WRAPS) stakeholder groups' development…

Participatory assessment of soil erosion severity and performance of mitigation measures using stakeholder workshops in Koga catchment, Ethiopia.

Science.gov (United States)

Jemberu, Walle; Baartman, Jantiene E M; Fleskens, Luuk; Ritsema, Coen J

2018-02-01

Farmers possess a wealth of knowledge regarding soil erosion and soil and water conservation (SWC), and there is a great demand to access it. However, there has been little effort to systematically document farmers' experiences and perceptions of SWC measures. Sustainable Land Management (SLM) has largely evolved through local traditional practices rather than adoption based on scientific evidence. This research aimed to assess soil erosion and performance of different SWC measures from the farmers' perspective by documenting their perceptions and experiences in Koga catchment, Ethiopia. To this aim, workshops were organised in three sub-catchments differing in slopes and SWC measures. Workshops included group discussions and field monitoring of erosion indicators and systematically describing the status of soil erosion, soil fertility and yield to assess the performance of SWC measures. Results show that farmers are aware of the harmful effects of ongoing soil erosion and of the impacts of mitigation measures on their farms. Sheet erosion was found to be the most widespread form of erosion while rill damage was critical on plots cultivated to cereals on steep slopes. The average rill erosion rates were 24.2 and 47.3 t/ha/y in treated and untreated farmlands, respectively. SWC reduced rill erosion on average by more than 48%. However, the impacts of SWC measures varied significantly between sub-watersheds, and farmers believed that SWC measures did not prevent erosion completely. Comparatively, graded stone-faced soil bunds revealed maximum desired impacts and were most appreciated by farmers, whereas level bunds caused water logging. Most traditional ditches were highly graded and begun incising and affected production of cereals. Despite the semi-quantitative nature of the methodology, using farmers' perceptions and experiences to document land degradation and the impacts of SWC measures is crucial as they are the daily users of the land and therefore directly

Anthropogenic changes and environmental degradation in pre-Hispanic and post-Colonial periods: soil erosion modelled with WEPP during Late Holocene in Teotihuacán Valley (central Mexico)

Science.gov (United States)

Lourdes González-Arqueros, M.; Mendoza Cantú, Manuel E.

2015-04-01

Land use changes and support practices are a worldwide significant issue in soil erosion and subsequently, land degradation. Anthropogenic changes, along different periods of the history in the last 2000 years in the Valley of Teotihuacan (central Mexico), highlight that soil erosion varies depending on how the management and the intensity of soil use is handled, considering the soils as a main resource. As a part of a broader effort to reconstruct the erosion dynamics in the Teotihuacán Valley through geoarchaeological approaches, this study apply a process-based watershed hydrology and upland erosion model, Water Erosion Prediction Project (WEPP). This research aims to contribute with insights through modelling and to recreate soil erosion and sedimentation dynamics in several historical periods with different environmental and anthropogenic scenarios. The Geo-spatial interface for WEPP (GeoWEPP) was used to characterize location of detachment, depositions and erosion predicted on the profile through time, based on current and hypothetical reconstructed conditions in the watershed. Climate, topography, soil and land use were used as inputs for the WEPP model to estimate runoff fluxes, soil loss rates, and sediment delivery ratio (SDR) for three historical scenarios: current period, reconstructed Teotihuacán period (AD 1-650), and reconstructed Aztec period (AD 1325-1520). Over a simulated and stablished timeframe for those social periods, the runoff, soil loss rate and SDR were estimated to be greater during the Aztec period. We assume that in general the climate conditions for this period were wetter, compared with present, in agreement with several authors that proposed climate reconstructions for the center of Mexico. It is also highlighted that support practices were more effective in this period. The next period with higher values is the current one, and fewer rates are estimated for the Teotihuacán period. This comparison release new arguments in the

Soil fertility and 137 Cs redistribution as related to land use, landscape and texture in a watershed of Paraiba State

International Nuclear Information System (INIS)

Santos, Antonio Clementino dos

2004-03-01

Intensive land use and growing deforestation of the natural vegetation in Northeastern Brazil have contributed to the degradation of resources, particularly the decrease of soil fertility. As a result, biodiversity and ecosystem capacity to restore its resources after disturbances have been diminished. The decrease in soil fertility is more substantial in areas dominated by an undulating topography. In these areas, erosion is intensified when crops or pasture replaces natural vegetation. Even though degradation processes are reflected in environmental, social, and economical changes, there is a lack of information regarding the interrelationship between these changes and soil fertility and erosion. Thus, the 'Vaca Brava' watershed (14,04 km 2 ), located in the 'Agreste' region of Paraiba State, was selected to study the interrelationships between land use, landscape, particle size distribution, soil fertility and erosion using 137 Cs redistribution. Small farms, where subsistence agriculture is intensive, are common in this watershed, as well as areas for environmental protection. A georreferenced survey of the watershed topography was initially carried out. Based on the survey data, the watershed was digitalized using a scale of 1:5000, and a 3-D map was created. Each landform element had its area determined on a area (absolute value) and percentage (relative value) basis. Shoulder, backslope and footslope positions represented 83% of the cultivated area in the watershed. A data base of 360 georreferenced soil samples (0-20 cm), collected using a stratified sampling scheme, was further created. Sites were stratified based on their landscape position (summit, shoulder, backslope, footslope, and toeslope) in factorial combination with land use (annual crops, pasture, Pennisetum purpureum, Mimosa caesalpiniae folia, bush fallow, and native forest). Physical analyses of the soil samples included particle size distribution and bulk density, whereas soil chemical

Restoring Anadromous Fish Habitat in the Lapwai Creek Watershed, Technical Report 2003-2006.

Energy Technology Data Exchange (ETDEWEB)

Rasmussen, Lynn

2007-02-01

The Restoring Anadromous Fish Habitat in the Lapwai Creek Watershed is a multi-phase project to enhance steelhead trout in the Lapwai Creek watershed by improving salmonid spawning and rearing habitat. Habitat is limited by extreme high runoff events, low summer flows, high water temperatures, poor instream cover, spawning gravel siltation, and sediment, nutrient and bacteria loading. Funded by the Bonneville Power Administration (BPA) as part of the Northwest Power Planning Council's Fish and Wildlife Program, the project assists in mitigating damage to steelhead runs caused by the Columbia River hydroelectric dams. The project is sponsored by the Nez Perce Soil and Water Conservation District (District). Target fish species include steelhead trout (Oncorhynchus mykiss). Steelhead trout within the Snake River Basin were listed in 1997 as threatened under the Endangered Species Act. Accomplishments for the contract period December 1, 2003 through February 28, 2004 include; seven grade stabilization structures, 0.67 acres of wetland plantings, ten acres tree planting, 500 linear feet streambank erosion control, two acres grass seeding, and 120 acres weed control.

Comparison of mercury mass loading in streams to atmospheric deposition in watersheds of Western North America: Evidence for non-atmospheric mercury sources

Science.gov (United States)

Domagalski, Joseph L.; Majewski, Michael S.; Alpers, Charles N.; Eckley, Chris S.; Eagles-Smith, Collin A.; Schenk, Liam N.; Wherry, Susan

2016-01-01

Annual stream loads of mercury (Hg) and inputs of wet and dry atmospheric Hg deposition to the landscape were investigated in watersheds of the Western United States and the Canadian-Alaskan Arctic. Mercury concentration and discharge data from flow gauging stations were used to compute annual mass loads with regression models. Measured wet and modeled dry deposition were compared to annual stream loads to compute ratios of Hg stream load to total Hg atmospheric deposition. Watershed land uses or cover included mining, undeveloped, urbanized, and mixed. Of 27 watersheds that were investigated, 15 had some degree of mining, either of Hg or precious metals (gold or silver), where Hg was used in the amalgamation process. Stream loads in excess of annual Hg atmospheric deposition (ratio > 1) were observed in watersheds containing Hg mines and in relatively small and medium-sized watersheds with gold or silver mines, however, larger watersheds containing gold or silver mines, some of which also contain large dams that trap sediment, were sometimes associated with lower load ratios (< 0.2). In the non-Arctic regions, watersheds with natural vegetation tended to have low ratios of stream load to Hg deposition (< 0.1), whereas urbanized areas had higher ratios (0.34–1.0) because of impervious surfaces. This indicated that, in ecosystems with natural vegetation, Hg is retained in the soil and may be transported subsequently to streams as a result of erosion or in association with dissolved organic carbon. Arctic watersheds (Mackenzie and Yukon Rivers) had a relatively elevated ratio of stream load to atmospheric deposition (0.27 and 0.74), possibly because of melting glaciers or permafrost releasing previously stored Hg to the streams. Overall, our research highlights the important role of watershed characteristics in determining whether a landscape is a net source of Hg or a net sink of atmospheric Hg.

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.

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.

Watershed-based survey designs

Science.gov (United States)

Detenbeck, N.E.; Cincotta, D.; Denver, J.M.; Greenlee, S.K.; Olsen, A.R.; Pitchford, A.M.

2005-01-01

Watershed-based sampling design and assessment tools help serve the multiple goals for water quality monitoring required under the Clean Water Act, including assessment of regional conditions to meet Section 305(b), identification of impaired water bodies or watersheds to meet Section 303(d), and development of empirical relationships between causes or sources of impairment and biological responses. Creation of GIS databases for hydrography, hydrologically corrected digital elevation models, and hydrologic derivatives such as watershed boundaries and upstream–downstream topology of subcatchments would provide a consistent seamless nationwide framework for these designs. The elements of a watershed-based sample framework can be represented either as a continuous infinite set defined by points along a linear stream network, or as a discrete set of watershed polygons. Watershed-based designs can be developed with existing probabilistic survey methods, including the use of unequal probability weighting, stratification, and two-stage frames for sampling. Case studies for monitoring of Atlantic Coastal Plain streams, West Virginia wadeable streams, and coastal Oregon streams illustrate three different approaches for selecting sites for watershed-based survey designs.

Land Use Cover Changes and Run Off Potention of Cipunten Agung Watershed Banten

Science.gov (United States)

Karima, A.; Kaswanto, R. L.

2017-10-01

The changes of landscape form such as Land Use Cover Changes (LUCC) of Cipunten Agung watershed could be identified periodically in 1995, 2005, and 2015. In general, land utilization in Cipunten Agung classified into protected region and cultivated region. In 2011, total of protected area is 885.80 ha or 22.54% of watershed area. Those conditions affected both positively to the community development and negatively to the water quantity condition in Cipunten Agung such as flooding, run off, and erosion. Therefore, the purpose of this research is to analyze LUCC impacts to run off potential in Cipunten Agung watershed. Supervised classification method and Soil Conservation Services (Qscs) approach were correlated to determine the figure out an optimal solution to reduce the rate of LUCC. Cipunten Agung watershed imagery was classified into five classes, namely water bodies, forest, cultivated tree, settlement and paddy field. The result shows that area of cultivation tree and paddy fields are larger than others in midstream, and settlement is denser in downstream, particularly at riparian landscapes. The LUCC into paddy field often occur at two period 1995 to 2005 and 2005 to 2015 with several area are 530.92 ha and 388.17 ha. The Qscs method calculation result for 1995 until 2015 was affected by land use cover composition in each year and it was defined by Curve Number (CN). High rainfall in 1995 was generating high run off potential volume. Nevertheless, curve number value was increase get near to 100, which indicate the potential of run off volume increases along with LUCC in each year, those are 70.95; 72.47; and 72.81.

Watershed Central: Harnessing a social media tool to organize local technical knowledge and find the right watershed resources for your watershed

Science.gov (United States)

Watershed Central was developed to be a bridge between sharing and searching for information relating to watershed issues. This is dependent upon active user support through additions and updates to the Watershed Central Wiki. Since the wiki is user driven, the content and applic...

Characterizing mercury concentrations and fluxes in a Coastal Plain watershed: Insights from dynamic modeling and data

Science.gov (United States)

Golden, H.E.; Knightes, C.D.; Conrads, P.A.; Davis, G.M.; Feaster, T.D.; Journey, C.A.; Benedict, S.T.; Brigham, M.E.; Bradley, P.M.

2012-01-01

Mercury (Hg) is one of the leading water quality concerns in surface waters of the United States. Although watershed-scale Hg cycling research has increased in the past two decades, advances in modeling watershed Hg processes in diverse physiographic regions, spatial scales, and land cover types are needed. The goal of this study was to assess Hg cycling in a Coastal Plain system using concentrations and fluxes estimated by multiple watershed-scale models with distinct mathematical frameworks reflecting different system dynamics. We simulated total mercury (HgT, the sum of filtered and particulate forms) concentrations and fluxes from a Coastal Plain watershed (McTier Creek) using three watershed Hg models and an empirical load model. Model output was compared with observed in-stream HgT. We found that shallow subsurface flow is a potentially important transport mechanism of particulate HgT during periods when connectivity between the uplands and surface waters is maximized. Other processes (e.g., stream bank erosion, sediment re-suspension) may increase particulate HgT in the water column. Simulations and data suggest that variable source area (VSA) flow and lack of rainfall interactions with surface soil horizons result in increased dissolved HgT concentrations unrelated to DOC mobilization following precipitation events. Although flushing of DOC-HgT complexes from surface soils can also occur during this period, DOC-complexed HgT becomes more important during base flow conditions. TOPLOAD simulations highlight saturated subsurface flow as a primary driver of daily HgT loadings, but shallow subsurface flow is important for HgT loads during high-flow events. Results suggest limited seasonal trends in HgT dynamics.

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.

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

Impact of urbanization on the sediment yield in tropical watershed using temporal land-use changes and a GIS-based model

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Bello Al-Amin D.

2017-09-01

Full Text Available Abundant rainfall areas promote sediment yield at both sub-watershed and watershed scale due to soil erosion and increase siltation of river channel, but it can be curtailed through planned urbanization. The urbanization of Skudai watershed is analysed from historical and future perspective. A GIS-based model (Hydrological Simulation Programme-FORTRAN-HSPF is used to modelled sediment flow using basin-wide simulation, and the output result is utilized in evaluating sediment yield reduction due to increased urbanization by swapping multiple temporal land-use of decadent time-steps. The analysis indicates that sediment yield reduces with increase urban built-up and decrease forest and agricultural land. An estimated 12 400 tons of sediment will be reduced for every 27% increase in built-up areas under high rainfall condition and 1 490 tons at low rainfall. The sensitivity analysis of land-use classes shows that built-up, forest and barren are more sensitive to sediment yield reduction compared to wetland and agricultural land at both high and low rainfall. The result of the study suggests that increased urbanization reduced sediment yield in proportion to the rainfall condition and can be used as an alternative approach for soil conservation at watershed scale independent of climate condition.

Application of the Kineros model for predicting the effect of land use on the surface run-off Case study in Brantas sub-watershed, Klojen District, Malang City, East Java Province of Indonesia

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Bisri Mohammad

2017-12-01

Full Text Available This study intended to illustrate the distribution of surface run-off. The methodology was by using Kineros model (kinetic run-off and erosion model. This model is a part of AGWA program which is as the development of ESRI ArcView SIG software that is as a tool for analysing hydrological phenomena in research about watershed simulating the process of infiltration, run-off depth, and erosion in a watershed of small scale such as ≤100 km2. The procedures are as follow: to analyse the run-off depth in Brantas sub-watershed, Klojen District by using Kineros model based on the land use change due to the rainfall simulation with the return period of 2 years, 5 years, 10 years, and 25 years. Results show that the difference of land use affect the surface run-off or there is the correlation between land use and surface run-off depth. The maximum surface run-off depth in the year 2000 was 134.26 mm; in 2005 it was 139.36 mm; and in 2010 it was 142.76 mm. There was no significant difference between Kineros model and observation in field, the relative error was only 9.09%.

Sediment transport dynamics in the Central Himalaya: assessing during monsoon the erosion processes signature in the daily suspended load of the Narayani river

Science.gov (United States)

Morin, Guillaume; Lavé, Jérôme; Lanord, Christian France; Prassad Gajurel, Ananta

2017-04-01

The evolution of mountainous landscapes is the result of competition between tectonic and erosional processes. In response to the creation of topography by tectonics, fluvial, glacial, and hillslope denudation processes erode topography, leading to rock exhumation and sediment redistribution. When trying to better document the links between climate, tectonic, or lithologic controls in mountain range evolution, a detailed understanding of the influence of each erosion process in a given environment is fundamental. At the scale of a whole mountain range, a systematic survey and monitoring of all the geomorphologic processes at work can rapidly become difficult. An alternative approach can be provided by studying the characteristics and temporal evolution of the sediments exported out of the range. In central Himalaya, the Narayani watershed presents contrasted lithologic, geochemical or isotopic signatures of the outcropping rocks as well as of the erosional processes: this particular setting allows conducting such type of approach by partly untangling the myopic vision of the spatial integration at the watershed scale. Based on the acquisition and analysis of a new dataset on the daily suspended load concentration and geochemical characteristics at the mountain outlet of one of the largest Himalayan rivers (drainage area = 30000 km2) bring several important results on Himalayan erosion, and on climatic and process controls. 1. Based on discrete depth sampling and on daily surface sampling of suspended load associated to flow characterization through ADCP measurements, we were first able to integrate sediment flux across a river cross-section and over time. We estimate for 2010 year an equivalent erosion rate of 1.8 +0.35/-0.2 mm/yr, and over the last 15 years, using past sediment load records from the DHM of Nepal, an equivalent erosion rate of 1.6 +0.3/-0.2 mm/yr. These rates are also in close agreement with the longer term ( 500 yrs) denudation rates of 1.7 mm

The experimental watersheds in Slovenia

International Nuclear Information System (INIS)

Sraj, M; Rusjan, S; Petan, S; Vidmar, A; Mikos, M; Globevnik, L; Brilly, M

2008-01-01

Experimental watersheds are critical to the advancement of hydrological science. By setting up three experimental watersheds, Slovenia also obtained its grounds for further development of the science and discipline. In the Dragonja experimental watershed the studies are focused on the afforestation of the watershed in a mediterranean climate, on the Reka river the water balance in a partly karstic area is examined, and on the case of the Glinscica stream the implications of the urban environment are studied. We have obtained valuable experience and tested new measuring equipment on all three experimental watersheds. Measurements and analysis on the experimental watersheds improved the current understanding of hydrological processes. They resulted in several PhD Theses, Master Theses and scientific articles. At the same time the experimental watersheds provide support to the teaching and studying process.

Storage in alluvial deposits controls the timing of particle delivery from large watersheds, filtering upland erosional signals and delaying benefits from watershed best management practices

Science.gov (United States)

Pizzuto, J. E.; Skalak, K.; Karwan, D. L.

2017-12-01

Transport of suspended sediment and sediment-borne constituents (here termed fluvial particles) through large river systems can be significantly influenced by episodic storage in floodplains and other alluvial deposits. Geomorphologists quantify the importance of storage using sediment budgets, but these data alone are insufficient to determine how storage influences the routing of fluvial particles through river corridors across large spatial scales. For steady state systems, models that combine sediment budget data with "waiting time distributions" (to define how long deposited particles remain stored until being remobilized) and velocities during transport events can provide useful predictions. Limited field data suggest that waiting time distributions are well represented by power laws, extending from 104 years, while the probability of storage defined by sediment budgets varies from 0.1 km-1 for small drainage basins to 0.001 km-1 for the world's largest watersheds. Timescales of particle delivery from large watersheds are determined by storage rather than by transport processes, with most particles requiring 102 -104 years to reach the basin outlet. These predictions suggest that erosional "signals" induced by climate change, tectonics, or anthropogenic activity will be transformed by storage before delivery to the outlets of large watersheds. In particular, best management practices (BMPs) implemented in upland source areas, designed to reduce the loading of fluvial particles to estuarine receiving waters, will not achieve their intended benefits for centuries (or longer). For transient systems, waiting time distributions cannot be constant, but will vary as portions of transient sediment "pulses" enter and are later released from storage. The delivery of sediment pulses under transient conditions can be predicted by adopting the hypothesis that the probability of erosion of stored particles will decrease with increasing "age" (where age is defined as the

Multi-Scale Soil Moisture Monitoring and Modeling at ARS Watersheds for NASA's Soil Moisture Active Passive (SMAP) Calibration/Validation Mission

Science.gov (United States)

Coopersmith, E. J.; Cosh, M. H.

2014-12-01

NASA's SMAP satellite, launched in November of 2014, produces estimates of average volumetric soil moisture at 3, 9, and 36-kilometer scales. The calibration and validation process of these estimates requires the generation of an identically-scaled soil moisture product from existing in-situ networks. This can be achieved via the integration of NLDAS precipitation data to perform calibration of models at each ­in-situ gauge. In turn, these models and the gauges' volumetric estimations are used to generate soil moisture estimates at a 500m scale throughout a given test watershed by leveraging, at each location, the gauge-calibrated models deemed most appropriate in terms of proximity, calibration efficacy, soil-textural similarity, and topography. Four ARS watersheds, located in Iowa, Oklahoma, Georgia, and Arizona are employed to demonstrate the utility of this approach. The South Fork watershed in Iowa represents the simplest case - the soil textures and topography are relative constants and the variability of soil moisture is simply tied to the spatial variability of precipitation. The Little Washita watershed in Oklahoma adds soil textural variability (but remains topographically simple), while the Little River watershed in Georgia incorporates topographic classification. Finally, the Walnut Gulch watershed in Arizona adds a dense precipitation network to be employed for even finer-scale modeling estimates. Results suggest RMSE values at or below the 4% volumetric standard adopted for the SMAP mission are attainable over the desired spatial scales via this integration of modeling efforts and existing in-situ networks.

Assessment of sediment yield using RS and GIS at two sub-basins of Dez Watershed, Iran

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Hamed Noori

2016-09-01

Full Text Available Soil erosion is a serious threat to soil and water resources in semi-arid regions. Modified Pacific South-west Inter Agency Committee (MPSIAC and Erosion Potential Method (EPM, as two well-known models, have shown their performance in many case studies. The goal of present study is to assess the efficiency of these methods for estimating the sediments yield and erosion intensity within short-term and long-term timeframes over two sub-basins of Dez watershed, west of Iran. The results showed that the study area can be categorized into slight, moderate, high and very high erosion zones. Almost half of the study area is highly susceptible to erosion due to the geological formations and land cover. Moreover, the long-term (i.e. 30 years sediment yield of 387 and 615 (kton y−1 estimated by MPSIAC and EPM models demonstrated the superiority of EPM. Compared to the measured value of 612 (kton y−1, the performance of EPM was astonishing. By splitting the dataset into six periods of five years, the sediment yield was predicted in short-term periods by both aforementioned methods. Such segmentation provides the opportunity to evaluate the impact of extreme flooding events on the models performances. The results showed that both models failed in estimation of sediment load during flood conditions. Nevertheless, the correlation coefficients for estimating the sediment yield were found to be R=0.93 and R=0.85 for EPM and MPSIAC models respectively, for short-term simulations.

Comparison of sediment and nutrient export and runoff characteristics from watersheds with centralized versus distributed stormwater management.

Science.gov (United States)

Hopkins, Kristina G; Loperfido, J V; Craig, Laura S; Noe, Gregory B; Hogan, Dianna M

2017-12-01

Stormwater control measures (SCMs) are used to retain stormwater and pollutants. SCMs have traditionally been installed in a centralized manner using detention to mitigate peak flows. Recently, distributed SCM networks that treat runoff near the source have been increasingly utilized. The aim of this study was to evaluate differences among watersheds that vary in SCM arrangement by assessing differences in baseflow nutrient (NO x -N and PO 4 - ) concentrations and fluxes, stormflow export of suspended sediments and particulate phosphorus (PP), and runoff characteristics. A paired watershed approach was used to compare export between 2004 and 2016 from one forested watershed (For-MD), one suburban watershed with centralized SCMs (Cent-MD), and one suburban watershed with distributed SCMs (Dist-MD). Results indicated baseflow nitrate (NO x -N) concentrations typically exceeded 1 mg-N/L in all watersheds and were highest in Dist-MD. Over the last 10 years in Dist-MD, nitrate concentrations in both stream baseflow and in a groundwater well declined as land use shifted from agriculture to suburban. Baseflow nitrate export temporarily increased during the construction phase of SCM development in Dist-MD. This temporary pulse of nitrate may be attributed to the conversion of sediment control facilities to SCMs and increased subsurface flushing as infiltration SCMs came on line. During storm flow, Dist-MD tended to have less runoff and lower maximum specific discharge than Cent-MD for small events (runoff responses became increasingly similar to Cent-MD with increasing precipitation (>1.3 cm). Mass export estimated during paired storm events indicated Dist-MD exported 30% less sediment and 31% more PP than Cent-MD. For large precipitation events, export of sediment and PP was similar among all three watersheds. Results suggest that distributed SCMs can reduce runoff and sediment loads during small rain events compared to centralized SCMs, but these differences become

Assessment of soil erosion by RUSLE model using remote sensing and GIS - A case study of Nethravathi Basin

Directory of Open Access Journals (Sweden)

B.P. Ganasri

2016-11-01

Full Text Available Soil erosion is a serious problem arising from agricultural intensification, land degradation and other anthropogenic activities. Assessment of soil erosion is useful in planning and conservation works in a watershed or basin. Modelling can provide a quantitative and consistent approach to estimate soil erosion and sediment yield under a wide range of conditions. In the present study, the soil loss model, Revised Universal Soil Loss Equation (RUSLE integrated with GIS has been used to estimate soil loss in the Nethravathi Basin located in the southwestern part of India. The Nethravathi Basin is a tropical coastal humid area having a drainage area of 3128 km2 up to the gauging station. The parameters of RUSLE model were estimated using remote sensing data and the erosion probability zones were determined using GIS. The estimated rainfall erosivity, soil erodibility, topographic and crop management factors range from 2948.16 to 4711.4 MJ/mm·ha−1hr−1/year, 0.10 to 0.44 t ha−1·MJ−1·mm−1, 0 to 92,774 and 0 to 0.63 respectively. The results indicate that the estimated total annual potential soil loss of about 473,339 t/yr is comparable with the measured sediment of 441,870 t/yr during the water year 2002–2003. The predicted soil erosion rate due to increase in agricultural area is about 14,673.5 t/yr. The probability zone map has been derived by the weighted overlay index method indicate that the major portion of the study area comes under low probability zone and only a small portion comes under high and very high probability zone. The results can certainly aid in implementation of soil management and conservation practices to reduce the soil erosion in the Nethravathi Basin.

Adopt Your Watershed

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U.S. Environmental Protection Agency — Adopt Your Watershed is a Website that encourages stewardship of the nation's water resources and serves as a national inventory of local watershed groups and...

Application of the Soil and Water Assessment Tool (SWAT Model on a small tropical island (Great River Watershed, Jamaica as a tool in Integrated Watershed and Coastal Zone Management

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Orville P. Grey

2014-09-01

Full Text Available The Great River Watershed, located in north-west Jamaica, is critical for development, particularly for housing, tourism, agriculture, and mining. It is a source of sediment and nutrient loading to the coastal environment including the Montego Bay Marine Park. We produced a modeling framework using the Soil and Water Assessment Tool (SWAT and GIS. The calculated model performance statistics for high flow discharge yielded a Nash-Sutcliffe Efficiency (NSE value of 0.68 and a R² value of 0.70 suggesting good measured and simulated (calibrated discharge correlation. Calibration and validation results for streamflow were similar to the observed streamflows. For the dry season the simulated urban landuse scenario predicted an increase in surface runoff in excess of 150%. During the wet season it is predicted to range from 98 to 234% presenting a significant risk of flooding, erosion and other environmental issues. The model should be used for the remaining 25 watersheds in Jamaica and elsewhere in the Caribbean. The models suggests that projected landuse changes will have serious impacts on available water (streamflow, stream health, potable water treatment, flooding and sensitive coastal ecosystems.

Meaningful Watershed Experiences for Middle and High School Students

Science.gov (United States)

Landry, Melinda; Smith, Cynthia; Greene, Joy

2014-05-01

Prince William County Public Schools and George Mason University in Virginia, USA, partnered to provide Meaningful Watershed Educational Experiences (MWEEs) for over 25,000 middle and high school students (11-18 year olds) across 34 schools. This school district, situated in a rapidly growing region 55 km southwest of Washington DC, has over 82,000 K-12 students. As native forest cover has been replaced with farming and urbanization, water quality has significantly degraded in the 166,534 km2 Chesapeake Bay watershed. This project was designed to increase student awareness of their impact on the land and waters of the largest estuary in the United States. MWEE is a long-term comprehensive project that incorporates a classroom preparation phase, a hands-on outdoor field investigation, and a reflection and data-sharing component. Training and technical assistance enhances the capacity of teachers of 6th grade, high school Earth Science and Environmental Science to deliver MWEEs which includes schoolyard stewardship, inquiry driven field study, use of hand-held technology and computer based mapping and analysis, project sharing and outreach. George Mason University researchers worked closely with K-12 science educators to create a comprehensive watershed-focused curriculum. Graduate and undergraduate students with strong interests in environmental science and education were trained to deliver the field investigation component of the MWEE. Representative teachers from each school were provided 3 days of professional development and were responsible for the training of their school's science education team. A comprehensive curriculum provided teachers with activities and tools designed to enhance students' mastery of state science objectives. Watershed concepts were used as the unifying theme to support student understanding of curriculum and STEM objectives including: scientific investigation, data collection and communication, chemistry, energy, erosion, human

Characteristics of symptomatic reflux episodes in Japanese proton pump inhibitor-refractory non-erosive reflux disease patients

Science.gov (United States)

Nakagawa, Kenichiro; Koike, Tomoyuki; Iijima, Katsunori; Saito, Masahiro; Kikuchi, Hiroki; Hatta, Waku; Ara, Nobuyuki; Uno, Kaname; Asano, Naoki; Shimosegawa, Tooru

2015-01-01

AIM: To clarify the pathogenesis of gastroesophageal reflux disease symptoms in non-erosive reflux disease (NERD) patients. METHODS: Thirty-five NERD patients with persistent symptoms, despite taking rabeprazole 10 mg twice daily for at least 8 wk, were included in this study. All patients underwent 24 h combined impedance - pH on rabeprazole. The symptom index (SI) was considered to be positive if ≥ 50%, and proximal reflux episodes were determined when reflux reached 15 cm above the proximal margin of the lower esophageal sphincter. RESULTS: In 14 (40%) SI-positive patients, with liquid weakly acid reflux, the occurrence rate of reflux symptoms was significantly more frequent in proximal reflux episodes (46.7%) than in distal ones (5.7%) (P acid reflux, there were no significant differences in the occurrence rate of reflux symptoms between proximal reflux episodes (38.5%) and distal ones (20.5%) (NS). With mixed liquid-gas weakly acid reflux, the occurrence rate of reflux symptoms in proximal reflux episodes was significantly more frequent (31.0%) than in distal reflux ones (3.3%) (P acid reflux, there were no significant differences in the occurrence rate of reflux symptoms between proximal reflux episodes (29.4%) and distal ones (14.3%) (NS). CONCLUSION: The proximal extent of weakly acidic liquid and mixed liquid-gas reflux is a major factor associated with reflux perception in SI-positive patients on proton pump inhibitor therapy. PMID:26715820

Geological, geotechnical and environmental evaluation of influence area of the oil production in the municipality of Mangaratiba, Rio de Janeiro, Brazil; Avaliacao geologico-geotecnica e ambiental da zona de influencia do duto petrolifero no municipio de Mangaratiba (RJ)

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Rodrigues, Andre Ferreira; Polivanov, Helena [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Inst. de Geociencias. Dept. de Geologia; Silva, Jorge Xavier da [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Inst. de Geociencias. Dept. de Geografia; Oliveira, Wilson J. de [PETROBRAS Engenharia, Rio de Janeiro, RJ (Brazil)

2004-07-01

This paper is applicable for a specials and strategies areas that must be permanently controlled called pipelines and their proximities. Those areas are liable to be under the influence of different situations like potential environmental risks - eg. conflagrations, floods, soil erosion, slumps and also accidental risks like located spills. Besides those negatives environmental situations, the pipelines also cross different regions that has an important natural resource like forests, watersheds, urban, industrial and agricultural areas. For main regulator of this work the pipeline was developed a series of maps that can be used single or overlayed with another maps. Those maps can be useful for Mangaratiba city urban management and demonstrate possible environmental risks that can occur on pipelines proximities of this city. (author)

Typhoon impacts on chemical weathering source provenance of a High Standing Island watershed, Taiwan

Science.gov (United States)

Meyer, Kevin J.; Carey, Anne E.; You, Chen-Feng

2017-10-01

Chemical weathering source provenance changes associated with Typhoon Mindulle (2004) were identified for the Choshui River Watershed in west-central Taiwan using radiogenic Sr isotope (87Sr/86Sr) and major ion chemistry analysis of water samples collected before, during, and following the storm event. Storm water sampling over 72 h was conducted in 3 h intervals, allowing for novel insight into weathering regime changes in response to intense rainfall events. Chemical weathering sources were determined to be bulk silicate and disseminated carbonate minerals at the surface and silicate contributions from deep thermal waters. Loss on ignition analysis of collected rock samples indicate disseminated carbonate can compose over 25% by weight of surface mineralogy, but typically makes up ∼2-3% of watershed rock. 87Sr/86Sr and major element molar ratios indicate that Typhoon Mindulle caused a weathering regime switch from normal flow incorporating a deep thermal signature to that of a system dominated by surface weathering. The data suggest release of silicate solute rich soil pore waters during storm events, creating a greater relative contribution of silicate weathering to the solute load during periods of increased precipitation and runoff. Partial depletion of this soil solute reservoir and possible erosion enhanced carbonate weathering lead to increased importance of carbonates to the weathering regime as the storm continues. Major ion data indicate that complex mica weathering (muscovite, biotite, illite, chlorite) may represent an important silicate weathering pathway in the watershed. Deep thermal waters represent an important contribution to river solutes during normal non-storm flow conditions. Sulfuric acid sourced from pyrite weathering is likely a major weathering agent in the Choshui River watershed.

Sources of suspended-sediment flux in streams of the chesapeake bay watershed: A regional application of the sparrow model

Science.gov (United States)

Brakebill, J.W.; Ator, S.W.; Schwarz, G.E.

2010-01-01

We describe the sources and transport of fluvial suspended sediment in nontidal streams of the Chesapeake Bay watershed and vicinity. We applied SPAtially Referenced Regressions on Watershed attributes, which spatially correlates estimated mean annual flux of suspended sediment in nontidal streams with sources of suspended sediment and transport factors. According to our model, urban development generates on average the greatest amount of suspended sediment per unit area (3,928 Mg/km2/year), although agriculture is much more widespread and is the greatest overall source of suspended sediment (57 Mg/km2/year). Factors affecting sediment transport from uplands to streams include mean basin slope, reservoirs, physiography, and soil permeability. On average, 59% of upland suspended sediment generated is temporarily stored along large rivers draining the Coastal Plain or in reservoirs throughout the watershed. Applying erosion and sediment controls from agriculture and urban development in areas of the northern Piedmont close to the upper Bay, where the combined effects of watershed characteristics on sediment transport have the greatest influence may be most helpful in mitigating sedimentation in the bay and its tributaries. Stream restoration efforts addressing floodplain and bank stabilization and incision may be more effective in smaller, headwater streams outside of the Coastal Plain. ?? 2010 American Water Resources Association. No claim to original U.S. government works.

Trends in precipitation and streamflow and changes in stream morphology in the Fountain Creek watershed, Colorado, 1939-99

Science.gov (United States)

Stogner, Sr., Robert W.

2000-01-01

The Fountain Creek watershed, located in and along the eastern slope of the Front Range section of the southern Rocky Mountains, drains approximately 930 square miles of parts of Teller, El Paso, and Pueblo Counties in eastern Colorado. Streamflow in the watershed is dominated by spring snowmelt runoff and storm runoff during the summer monsoon season. Flooding during the 1990?s has resulted in increased streambank erosion. Property loss and damage associated with flooding and bank erosion has cost area residents, businesses, utilities, municipalities, and State and Federal agencies millions of dollars. Precipitation (4 stations) and streamflow (6 stations) data, aerial photographs, and channel reconnaissance were used to evaluate trends in precipitation and streamflow and changes in channel morphology. Trends were evaluated for pre-1977, post-1976, and period-of-record time periods. Analysis revealed the lack of trend in total annual and seasonal precipitation during the pre-1977 time period. In general, the analysis also revealed the lack of trend in seasonal precipitation for all except the spring season during the post-1976 time period. Trend analysis revealed a significant upward trend in long-term (period of record) total annual and spring precipitation data, apparently due to a change in total annual precipitation throughout the Fountain Creek watershed. During the pre-1977 time period, precipitation was generally below average; during the post- 1976 time period, total annual precipitation was generally above average. During the post- 1976 time period, an upward trend in total annual and spring precipitation was indicated at two stations. Because two of four stations evaluated had upward trends for the post-1976 period and storms that produce the most precipitation are isolated convection storms, it is plausible that other parts of the watershed had upward precipitation trends that could affect trends in streamflow. Also, because of the isolated nature of

The role of interior watershed processes in improving parameter estimation and performance of watershed models.

Science.gov (United States)

Yen, Haw; Bailey, Ryan T; Arabi, Mazdak; Ahmadi, Mehdi; White, Michael J; Arnold, Jeffrey G

2014-09-01

Watershed models typically are evaluated solely through comparison of in-stream water and nutrient fluxes with measured data using established performance criteria, whereas processes and responses within the interior of the watershed that govern these global fluxes often are neglected. Due to the large number of parameters at the disposal of these models, circumstances may arise in which excellent global results are achieved using inaccurate magnitudes of these "intra-watershed" responses. When used for scenario analysis, a given model hence may inaccurately predict the global, in-stream effect of implementing land-use practices at the interior of the watershed. In this study, data regarding internal watershed behavior are used to constrain parameter estimation to maintain realistic intra-watershed responses while also matching available in-stream monitoring data. The methodology is demonstrated for the Eagle Creek Watershed in central Indiana. Streamflow and nitrate (NO) loading are used as global in-stream comparisons, with two process responses, the annual mass of denitrification and the ratio of NO losses from subsurface and surface flow, used to constrain parameter estimation. Results show that imposing these constraints not only yields realistic internal watershed behavior but also provides good in-stream comparisons. Results further demonstrate that in the absence of incorporating intra-watershed constraints, evaluation of nutrient abatement strategies could be misleading, even though typical performance criteria are satisfied. Incorporating intra-watershed responses yields a watershed model that more accurately represents the observed behavior of the system and hence a tool that can be used with confidence in scenario evaluation. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

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