Multi-scale wind erosion monitoring and assessment for US rangelands

Science.gov (United States)

Wind erosion is a major resource concern for rangeland managers. Although wind erosion is a naturally occurring process in many drylands, land use activities, and land management in particular, can accelerate wind-driven soil loss – impacting ecosystem dynamics and agricultural production, air quali...

Determining Wind Erosion in the Great Plains

OpenAIRE

Elwin G. Smith; Burton C. English

1982-01-01

Wind erosion is defined as the movement of soil particles resulting from strong turbulent winds. The movement of soil particles can be categorized as suspension, saltation, or surface creep. Fine soil particles can be suspended in the atmosphere and carried for great distances. Particles too large to be suspended move in a jumping action along the soil surface, known as saltation. Heavier particles have a rolling movement along the surface and this type of erosion is surface creep.

Accelerated rain erosion of wind turbine blade coatings

DEFF Research Database (Denmark)

Zhang, Shizhong

. There are four chapters in the thesis. In chapter 1, a literature survey provides background information to the field. Topics discussed are the global wind energy development, possible wind turbine constructions, blade structures and materials, blade coatings, and liquid erosion mechanisms. In chapter 2......During operation, the fast-moving blades of wind turbines are exposed to continuous impacts with rain droplets, hail, insects, or solid particles. This can lead to erosion of the blades, whereby the electrical efficiency is compromised and expensive repairs may be required. One possible solution...

Determination of wind erosion intensity on heavy clay soils

Directory of Open Access Journals (Sweden)

Jana Kozlovsky Dufková

2010-01-01

Full Text Available Wind erosion, common problem of light-textured soils, was determined on heavy clay soils in the foothills of Bílé Karpaty Mountains, Czech Republic. Soil erodibility by wind was determined from the Map of potential erodibility of soil by wind and from the calculation of potential and real soil loss by wind. All the determinations show underestimation of soil erodibility by wind on heavy clay soils, because methods that are used for this are based above all on the assessment of clay particles content and the presumption the more clay particles soil contains, the less vulnerable to wind erosion is. The potential erodibility of soil by wind is 0,09 t . ha−1 per year. The determined value does not exceed the tolerable soil loss limit 10 t . ha−1 per year for deep soils. The real average erodibility of soil by wind has the highest value 1,47 g . m−2 on November 30th, 2008. Other soil losses that do not exceed the tolerable soil loss limit 1,4 g . m−2, were determined on March 18th and 28th, 2008. Big difficulties come with the assessment of the erodibility of heavy clay soils in the areas, where soil erosion ve­ri­fia­bly exists, but it is not assessable by objective calculating methods. Evident necessity of new know­ledge concerning the determination of wind erosion intensity follows from the results.

Climate change and wind erosion by dust storms

International Nuclear Information System (INIS)

Wheaton, E.E.; Wittrock, V.

1991-01-01

Dust storms and their associated wind erosion are thought to be almost synonymous with drought. Dust storms have varying impacts including sandblasting and burying crops, wind erosion of soil, health effects and traffic accidents. A comparison of drought periods for southern Saskatchewan with dust storm frequencies for the period 1977-1988 revealed that the worst drought conditions coincided with the greatest April dust storm frequencies, with 1981 having the worst drought, and secondary spring droughts occurring in 1977, 1988, 1980 and 1982, and spring dust storm peaks occurring, in order of magnitude, in 1981, 1977, 1987, and 1982. An increase in atmospheric dust particles may lead to enhanced atmospheric subsidence and associated drought, and could be a positive feedback for drought intensity. Wind erosion potential may rise with rising temperature due to decreased vegetation cover, but the effect might be offset by rising precipitation

Soil erosion rates caused by wind and saltating sand stresses in a wind tunnel

International Nuclear Information System (INIS)

Ligotke, M.W.

1993-02-01

Wind erosion tests were performed in a wind tunnel in support of the development of long-term protective barriers to cap stabilized waste sites at the Hanford Site. Controlled wind and saltating sand erosive stresses were applied to physical models of barrier surface layers to simulate worst-case eolian erosive stresses. The goal of these tests was to provide information useful to the design and evaluation of the surface layer composition of an arid-region waste site barrier concept that incorporates a deep fine-soil reservoir. A surface layer composition is needed that will form an armor resistant to eolian erosion during periods of extreme dry climatic conditions, especially when such conditions result in the elimination or reduction of vegetation by water deprivation or wildfire. Because of the life span required of Hanford waste barriers, it is important that additional work follow these wind tunnel studies. A modeling effort is planned to aid the interpretation of test results with respect to the suitability of pea gravel to protect the finite-soil reservoir during long periods of climatic stress. It is additionally recommended that wind tunnel tests be continued and field data be obtained at prototype or actual barrier sites. Results wig contribute to barrier design efforts and provide confidence in the design of long-term waste site caps for and regions

Crater Mound Formation by Wind Erosion on Mars

Science.gov (United States)

Steele, L. J.; Kite, E. S.; Michaels, T. I.

2018-01-01

Most of Mars' ancient sedimentary rocks by volume are in wind-eroded sedimentary mounds within impact craters and canyons, but the connections between mound form and wind erosion are unclear. We perform mesoscale simulations of different crater and mound morphologies to understand the formation of sedimentary mounds. As crater depth increases, slope winds produce increased erosion near the base of the crater wall, forming mounds. Peak erosion rates occur when the crater depth is ˜2 km. Mound evolution depends on the size of the host crater. In smaller craters mounds preferentially erode at the top, becoming more squat, while in larger craters mounds become steeper sided. This agrees with observations where smaller craters tend to have proportionally shorter mounds and larger craters have mounds encircled by moats. If a large-scale sedimentary layer blankets a crater, then as the layer recedes across the crater it will erode more toward the edges of the crater, resulting in a crescent-shaped moat. When a 160 km diameter mound-hosting crater is subject to a prevailing wind, the surface wind stress is stronger on the leeward side than on the windward side. This results in the center of the mound appearing to "march upwind" over time and forming a "bat-wing" shape, as is observed for Mount Sharp in Gale crater.

An extreme wind erosion event of the fresh Eyjafjallajökull 2010 volcanic ash.

Science.gov (United States)

Arnalds, Olafur; Thorarinsdottir, Elin Fjola; Thorsson, Johann; Waldhauserova, Pavla Dagsson; Agustsdottir, Anna Maria

2013-01-01

Volcanic eruptions can generate widespread deposits of ash that are subsequently subjected to erosive forces which causes detrimental effects on ecosystems. We measured wind erosion of the freshly deposited Eyjafjallajökull ash at a field site the first summer after the 2010 eruption. Over 30 wind erosion events occurred (June-October) at wind speeds > 10 m s(-1) in each storm with gusts up to 38.7 m s(-1). Surface transport over one m wide transect (surface to 150 cm height) reached > 11,800 kg m(-1) during the most intense storm event with a rate of 1,440 kg m(-1) hr(-1) for about 6½ hrs. This storm is among the most extreme wind erosion events recorded on Earth. The Eyjafjallajökull wind erosion storms caused dust emissions extending several hundred km from the volcano affecting both air quality and ecosystems showing how wind erosion of freshly deposited ash prolongs impacts of volcanic eruptions.

Relative contributions of wind and water erosion to total soil loss and its effect on soil properties in sloping croplands of the Chinese Loess Plateau.

Science.gov (United States)

Tuo, Dengfeng; Xu, Mingxiang; Gao, Guangyao

2018-08-15

Wind and water erosion are two dominant types of erosion that lead to soil and nutrient losses. Wind and water erosion may occur simultaneously to varying extents in semi-arid regions. The contributions of wind and water erosion to total erosion and their effects on soil quality, however, remains elusive. We used cesium-137 ( 137 Cs) inventories to estimate the total soil erosion and used the Revised Universal Soil Loss Equation (RUSLE) to quantify water erosion in sloping croplands. Wind erosion was estimated from the subtraction of the two. We also used 137 Cs inventories to calculate total soil erosion and validate the relationships of the soil quality and erosion at different slope aspects and positions. The results showed that wind erosion (1460tkm -2 a -1 ) on northwest-facing slope was responsible for approximately 39.7% of the total soil loss, and water erosion (2216tkm -2 a -1 ) accounted for approximately 60.3%. The erosion rates were 58.8% higher on northwest- than on southeast-facing slopes. Northwest-facing slopes had lower soil organic carbon, total nitrogen, clay, and silt contents than southeast-facing slopes, and thus, the 137 Cs inventories were lower, and the total soil erosions were higher on the northwest-facing slopes. The variations in soil physicochemical properties were related to total soil erosion. The lowest 137 Cs inventories and nutrient contents were recorded at the upper positions on the northwest-facing slopes due to the successive occurrence of more severe wind and water erosion at the same site. The results indicated that wind and water could accelerate the spatial variability of erosion rate and soil properties and cause serious decreases in the nutrient contents in sloping fields. Our research could help researchers develop soil strategies to reduce soil erosion according to the dominant erosion type when it occurs in a hilly agricultural area. Copyright © 2018 Elsevier B.V. All rights reserved.

A New Instrument for Testing Wind Erosion by Soil Surface Shape Change

International Nuclear Information System (INIS)

Hai, C.; Yuan, X.; Jiang, H.; Zhou, R.; Wang, J.; Liu, B.; Ye, Y.; Du, P.

2010-01-01

Wind erosion, a primary cause of soil degeneration, is a problem in arid and semiarid areas throughout the world. Many methods are available to study soil erosion, but there is no an effective method for making quantitative measurements in the field. To solve this problem, we have developed a new instrument that can measure the change in the shape of the soil surface, allowing quick quantification of wind erosion. In this paper, the construction and principle of the new instrument are described. Field experiments are carried out using the instrument, and the data are analyzed. The erosion depth is found to vary by 11% compared to the average for measurement areas ranging from 30 x 30 cm 2 to 10 x 10 cm 2 . The results show that the instrument is convenient and reliable for quantitatively measuring wind erosion in the field.

Using albedo to reform wind erosion modelling, mapping and monitoring

Science.gov (United States)

Chappell, Adrian; Webb, Nicholas P.

2016-12-01

Wind erosion and dust emission models are used to assess the impacts of dust on radiative forcing in the atmosphere, cloud formation, nutrient fertilisation and human health. The models are underpinned by a two-dimensional geometric property (lateral cover; L) used to characterise the three-dimensional aerodynamic roughness (sheltered area or wakes) of the Earth's surface and calibrate the momentum it extracts from the wind. We reveal a fundamental weakness in L and demonstrate that values are an order of magnitude too small and significant aerodynamic interactions between roughness elements and their sheltered areas have been omitted, particularly under sparse surface roughness. We describe a solution which develops published work to establish a relation between sheltered area and the proportion of shadow over a given area; the inverse of direct beam directional hemispherical reflectance (black sky albedo; BSA). We show direct relations between shadow and wind tunnel measurements and thereby provide direct calibrations of key aerodynamic properties. Estimation of the aerodynamic parameters from albedo enables wind erosion assessments over areas, across platforms from the field to airborne and readily available satellite data. Our new approach demonstrated redundancy in existing wind erosion models and thereby reduced model complexity and improved fidelity. We found that the use of albedo enabled an adequate description of aerodynamic sheltering to characterise fluid dynamics and predict sediment transport without the use of a drag partition scheme (Rt) or threshold friction velocity (u∗t). We applied the calibrations to produce global maps of aerodynamic properties which showed very similar spatial patterns to each other and confirmed the redundancy in the traditional parameters of wind erosion modelling. We evaluated temporal patterns of predicted horizontal mass flux at locations across Australia which revealed variation between land cover types that would not

Wind erosion in the Sahelian zone of Niger : processes, models, and control techniques

NARCIS (Netherlands)

Sterk, G.

1997-01-01

In the Sahelian zone of Niger, severe wind erosion occurs mainly in the first half of the rainy season (May - July), when violent winds preceding thunderstorms result in intense sediment transport. Quantification of this wind erosion is difficult due to a high degree of temporal and spatial

Effect of vegetation cover and transitions on regional wind erosion in drylands

NARCIS (Netherlands)

Youssef, I.F.

2012-01-01

Wind erosion is a critical environmental problem that threatens mainly the arid and semi-arid regions of our planet. Usually this problem is associated with desertification, poverty and other environmental and socioeconomic problems. Wind erosion causes the loss of fertile topsoil, and has a

Farmers' perceptions of erosion by wind and water in northern Burkina Faso

NARCIS (Netherlands)

Visser, S.M.; Leenders, J.K.; Leeuwis, M.

2003-01-01

Wind and water erosion are widespread phenomena throughout the Sahel, especially in the early rainy season, when high-intensity rainstorms are often preceded by severe windstorms. This paper describes the results of a survey on the farmers' perceptions of wind and water erosion processes and control

Estimation of wind erosion from construction of a railway in arid Northwest China

Directory of Open Access Journals (Sweden)

Benli Liu

2017-06-01

Full Text Available A state-of-the-art wind erosion simulation model, the Wind Erosion Prediction System and the United States Environmental Protection Agency's AP 42 emission factors formula, were combined together to evaluate wind-blown dust emissions from various construction units from a railway construction project in the dry Gobi land in Northwest China. The influence of the climatic factors: temperature, precipitation, wind speed and direction, soil condition, protective measures, and construction disturbance were taken into account. Driven by daily and sub-daily climate data and using specific detailed management files, the process-based WEPS model was able to express the beginning, active, and ending phases of construction, as well as the degree of disturbance for the entire scope of a construction project. The Lanzhou-Xinjiang High-speed Railway was selected as a representative study because of the diversities of different climates, soil, and working schedule conditions that could be analyzed. Wind erosion from different working units included the building of roadbeds, bridges, plants, temporary houses, earth spoil and barrow pit areas, and vehicle transportation were calculated. The total wind erosion emissions, 7406 t, for the first construction area of section LXS-15 with a 14.877 km length was obtained for quantitative analysis. The method used is applicable for evaluating wind erosion from other complex surface disturbance projects.

Wind Erosion Processes and Control Techniques in the Sahelian Zone of Niger

NARCIS (Netherlands)

Sterk, G.; Stroosnijder, L.; Raats, P.A.C.

1999-01-01

Wind Erosion Processes and Control Techniques in the Sahelian Zone of Niger G. Sterk, L. Stroosnijder, and P.A.C. Raats Abstract The objective of this paper is to present the main results and conclusions from three years of field research on wind erosion processes and control techniques in the

Early-season wind erosion influenced by soil-incorporated green manure in the Pacific Northwest

Science.gov (United States)

Management strategies are sought to minimize wind erosion of irrigated agricultural soils along the Columbia River of the Inland Pacific Northwest, particularly during the early season (March-April) when high winds coincide with sowing of vegetable crops. Early-season wind erosion potential from soi...

Wind erosion potential of a winter wheat-summer fallow rotation after land application of biosolids

Science.gov (United States)

Pi, Huawei; Sharratt, Brenton; Schillinger, William F.; Bary, Andrew I.; Cogger, Craig G.

2018-06-01

Conservation tillage is a viable management strategy to control soil wind erosion, but other strategies such as land application of biosolids that enhance soil quality may also reduce wind erosion. No studies have determined the effects of biosolids on wind erosion. Wind erosion potential of a silt loam was assessed using a portable wind tunnel after applying synthetic and biosolids fertilizer to traditional (disk) and conservation (undercutter) tillage practices during the summer fallow phase of a winter wheat-summer fallow (WW-SF) rotation in 2015 and 2016 in east-central Washington. Soil loss ranged from 12 to 61% lower for undercutter than disk tillage, possibly due to retention of more biomass on the soil surface of the undercutter versus disk tillage treatment. In contrast, soil loss was similar to or lower for biosolids as compared with synthetic fertilizer treatment. Our results suggest that biosolids applications to agricultural lands will have minimal impact on wind erosion.

Mechanics of Interrill Erosion with Wind-Driven Rain (WDR)

Science.gov (United States)

This article provides an evaluation analysis for the performance of the interrill component of the Water Erosion Prediction Project (WEPP) model for Wind-Driven Rain (WDR) events. The interrill delivery rates (Di) were collected in the wind tunnel rainfall simulator facility of the International Cen...

Wind Erosion Induced Soil Degradation in Northern China: Status, Measures and Perspective

Directory of Open Access Journals (Sweden)

Zhongling Guo

2014-12-01

Full Text Available Soil degradation is one of the most serious ecological problems in the world. In arid and semi-arid northern China, soil degradation predominantly arises from wind erosion. Trends in soil degradation caused by wind erosion in northern China frequently change with human activities and climatic change. To decrease soil loss by wind erosion and enhance local ecosystems, the Chinese government has been encouraging residents to reduce wind-induced soil degradation through a series of national policies and several ecological projects, such as the Natural Forest Protection Program, the National Action Program to Combat Desertification, the “Three Norths” Shelter Forest System, the Beijing-Tianjin Sand Source Control Engineering Project, and the Grain for Green Project. All these were implemented a number of decades ago, and have thus created many land management practices and control techniques across different landscapes. These measures include conservation tillage, windbreak networks, checkerboard barriers, the Non-Watering and Tube-Protecting Planting Technique, afforestation, grassland enclosures, etc. As a result, the aeolian degradation of land has been controlled in many regions of arid and semiarid northern China. However, the challenge of mitigating and further reversing soil degradation caused by wind erosion still remains.

WIND EROSION INTENSITY DETERMINATION USING SOIL PARTICLE CATCHER DEVICES

Directory of Open Access Journals (Sweden)

Lenka Lackóová

2013-12-01

Full Text Available To analyze wind erosion events in the real terrain conditions, we proposed to construct a prototype of soil particle catcher devices to trap soil particles. With these devices we are able to measure the intensity of wind erosion at six different heights above the soil surface in one location or at three different heights in two places. It is possible to use them for six different places at the same time as well. We performed field measurements to determine the amount of soil particles transported by the wind between 26th – 31st March 2012. Each measuring took 60 minutes. After this time the soil particle catchers were emptied and further measurements carried out. At the beginning we selected two places for measurement (soil HPJ 16 and 37 at two heights, one above the other. Then we used two measuring systems 40 m apart at two sites (D2 and D4 and the soil captured at two heights (0, 1. The maximum weight of soil particles trapped in measuring system D2 at height (0 was 1242.7 g at a wind speed of 9.6 ms-1. At measurement height (1 the maximum weight was 72.7 g trapped at the same average hourly rate, but during different measurement events. The measuring system at D4 trapped the highest amount of soil at a wind speed of 8.9 ms-1 (1141.7 g at height (0 and at a speed of 9.3 ms-1 (22.3 g at height (1. During the measurements with the two basic measuring systems D4 and D2, we measured the wind erosion intensity together with soil particle catchers D1 and D3. D3 was placed between devices D4 and D2, D1 was 20 m ahead D2. Soil particle catchers were placed on the soil surface at height position (0. We measured increasing soil erosion downwind on four locations spaced at 20 m. The results show that with there is an increasing quantity of particles collected as the erosive surface length increases, due to the so-called snowball effect. We analyzed selected trapped soil samples in order to determine the size of the soil particles and their proportion

Wind erosion in semiarid landscapes: Predictive models and remote sensing methods for the influence of vegetation

Science.gov (United States)

Musick, H. Brad

1993-01-01

The objectives of this research are: to develop and test predictive relations for the quantitative influence of vegetation canopy structure on wind erosion of semiarid rangeland soils, and to develop remote sensing methods for measuring the canopy structural parameters that determine sheltering against wind erosion. The influence of canopy structure on wind erosion will be investigated by means of wind-tunnel and field experiments using structural variables identified by the wind-tunnel and field experiments using model roughness elements to simulate plant canopies. The canopy structural variables identified by the wind-tunnel and field experiments as important in determining vegetative sheltering against wind erosion will then be measured at a number of naturally vegetated field sites and compared with estimates of these variables derived from analysis of remotely sensed data.

Wind tunnel experiments on the effects of tillage ridge features on wind erosion horizontal fluxes

Directory of Open Access Journals (Sweden)

M. Kardous

2005-11-01

Full Text Available In addition to the well-known soil factors which control wind erosion on flat, unridged surfaces, two specific processes affect the susceptibility of tillage ridged surfaces to wind erosion: ridge-induced roughness and ridge- trapping efficiency. In order to parameterize horizontal soil fluxes produced by wind over tillage ridges, eight-ridge configurations composed of sandy soil and exhibiting ridge heights to ridge spacing (RH/RS ratios ranging from 0.18 to 0.38 were experimented in a wind tunnel. These experiments are used to develop a parameterization of the horizontal fluxes over tillage ridged surfaces based only on the geometric characteristics of the ridges. Indeed, the key parameters controlling the horizontal flux, namely the friction velocity, threshold friction velocity and the adjustment coefficient, are derived through specific expressions, from ridge heights (RH and ridge spacing (RS. This parameterization was evaluated by comparing the results of the simulations to an additional experimental data set and to the data set obtained by Hagen and Armbrust (1992. In both cases, predicted and measured values are found to be in a satisfying agreement. This parameterization was used to evaluate the efficiency of ridges in reducing wind erosion. The results show that ridged surfaces, when compared to a loose, unridged soil surface, lead to an important reduction in the horizontal fluxes (exceeding 60%. Moreover, the effect of ridges in trapping particles contributes for more than 90% in the flux reduction while the ridge roughness effect is weak and decreases when the wind velocity increases.

Wind erosion potential of a winter wheat–summer fallow rotation after land application of biosolids

Science.gov (United States)

While land application of biosolids is recognized as a sustainable management practice for enhancing soil health, no studies have determined the effects of biosolids on soil wind erosion. Wind erosion potential of a silt loam was assessed using a portable wind tunnel after applying synthetic and bio...

Wind erosion control with scattered vegetation in the Sahelian zone of Burkina Faso

NARCIS (Netherlands)

Leenders, J.K.

2006-01-01

The Sahelian zone ofAfricais the region that is globally most subjected to land degradation, with wind erosion being the most important soil degradation process. By using control measures, the negative effects of wind erosion can be reduced. At present, adoption of

Wind driven erosion and the effects of particulate electrification

Science.gov (United States)

Merrison, J. P.; Bak, E.; Finster, K.; Gunnlaugsson, H. P.; Holstein-Rathlou, C.; Knak Jensen, S.; Nørnberg, P.; Rasmussen, K. R.

2012-09-01

Several related aspects of Aeolian activity are presently being studied in the laboratory, the most recent advances in this field will be presented. These include simulating wind driven erosion in the laboratory, quantifying erosion rates and the study of mineral change due to mechanical activation. Also advances in our understanding of the electrification of sand/dust particles is being made and how this phenomenon affects their behavior.

Soil deflation analyses from wind erosion events

Directory of Open Access Journals (Sweden)

Lenka Lackóová

2015-09-01

Full Text Available There are various methods to assess soil erodibility for wind erosion. This paper focuses on aggregate analysis by a laser particle sizer ANALYSETTE 22 (FRITSCH GmbH, made to determine the size distribution of soil particles detached by wind (deflated particles. Ten soil samples, trapped along the same length of the erosion surface (150–155 m but at different wind speeds, were analysed. The soil was sampled from a flat, smooth area without vegetation cover or soil crust, not affected by the impact of windbreaks or other barriers, from a depth of maximum 2.5 cm. Prior to analysis the samples were prepared according to the relevant specifications. An experiment was also conducted using a device that enables characterisation of the vertical movement of the deflated material. The trapped samples showed no differences in particle size and the proportions of size fractions at different hourly average wind speeds. It was observed that most of particles travelling in saltation mode (size 50–500 μm – 58–70% – moved vertically up to 26 cm above the soil surface. At greater heights, particles moving in suspension mode (floating in the air; size < 100 μm accounted for up to 90% of the samples. This result suggests that the boundary between the two modes of the vertical movement of deflated soil particles lies at about 25 cm above the soil surface.

A history of wind erosion prediction models in the United States Department of Agriculture: The Wind Erosion Prediction System (WEPS)

Science.gov (United States)

Development of the Wind Erosion Prediction System (WEPS) was officially inaugurated in 1985 by United States Department of Agriculture-Agricultural Research Service (USDA-ARS) scientists in response to customer requests, particularly those coming from the USDA Soil Conservation Service (SCS), for im...

Wind tunnel experiments on the effects of tillage ridge features on wind erosion horizontal fluxes

Directory of Open Access Journals (Sweden)

M. Kardous

2005-11-01

Full Text Available In addition to the well-known soil factors which control wind erosion on flat, unridged surfaces, two specific processes affect the susceptibility of tillage ridged surfaces to wind erosion: ridge-induced roughness and ridge- trapping efficiency.

In order to parameterize horizontal soil fluxes produced by wind over tillage ridges, eight-ridge configurations composed of sandy soil and exhibiting ridge heights to ridge spacing (RH/RS ratios ranging from 0.18 to 0.38 were experimented in a wind tunnel. These experiments are used to develop a parameterization of the horizontal fluxes over tillage ridged surfaces based only on the geometric characteristics of the ridges. Indeed, the key parameters controlling the horizontal flux, namely the friction velocity, threshold friction velocity and the adjustment coefficient, are derived through specific expressions, from ridge heights (RH and ridge spacing (RS. This parameterization was evaluated by comparing the results of the simulations to an additional experimental data set and to the data set obtained by Hagen and Armbrust (1992. In both cases, predicted and measured values are found to be in a satisfying agreement.

This parameterization was used to evaluate the efficiency of ridges in reducing wind erosion. The results show that ridged surfaces, when compared to a loose, unridged soil surface, lead to an important reduction in the horizontal fluxes (exceeding 60%. Moreover, the effect of ridges in trapping particles contributes for more than 90% in the flux reduction while the ridge roughness effect is weak and decreases when the wind velocity increases.

Soil erosion rates from mixed soil and gravel surfaces in a wind tunnel: A preliminary report

International Nuclear Information System (INIS)

Ligotke, M.W.

1988-12-01

Tests of wind erosion were performed in a controlled-environment wind tunnel to support the development of natural-material protective barriers for long-term isolation of radioactive waste. Barrier performance standards currently being developed for internal and external barrier performance are expected to mandate a surface layer that is resistant to wind erosion. The purpose of this study was to initiate a series of tests to determine suitable soil and gravel mixtures for such a barrier and to test worst-case surface layer conditions under the influence of high wind speeds. Six mixed soil and gravel surfaces were prepared, weathered to represent natural wind-blown desert areas, and subjected to controlled wind erosion forces in a wind tunnel. The applied erosive forces, including surface shear forces, were characterized to provide a means of relating wind tunnel results with actual field conditions. Soil particle losses from the surfaces caused by suspension, saltation, and surface creep were monitored by aerosol sample probes and mass balance measurements. 23 refs., 22 figs., 3 tabs

Evaluation of the RWEQ and SWEEP in simulating soil and PM10 loss from a portable wind tunnel

Science.gov (United States)

Wind erosion threatens sustainable agriculture and environmental quality in the Columbia Plateau region of the US Pacific Northwest. Wind erosion models such as Wind Erosion Prediction System (WEPS) and the Revised Wind Erosion Equation (RWEQ) have been developed as tools for identifying practices t...

Soil tillage and windbreak effects on millet and cowpea: I. Wind speed, evaporation, and wind erosion

International Nuclear Information System (INIS)

Banzhaf, J.; Leihner, D.E.; Buerkert, A.; Serafini, P.G.

1992-01-01

Deforestation, overgrazing, and declining soil regeneration periods have resulted in increased wind erosion problems in dry areas of the West African Sahel, but little is known about the bio-physical factors involved. This research was conducted to determine the effects of ridging and four different windbreak spacings on wind erosion, potential evaporation, and soil water reserves. A field trial was conducted from 1985 to 1987 on 12 ha of a Psammentic Paleustalf in Southern Niger. Millet, Pennisetum glaucum (L.), and cowpea, Vigna unguiculata (L.) Walp., were seeded in strips on flat and ridged soil. Windbreaks of savannah vegetation were spaced at 6, 20, 40, and 90 m. The effects of ridging on wind speed, evaporation, and wind erosion were small and mostly non-significant. However, average wind speed at 0.3 m above ground in the center of cowpea and millet strips was significantly reduced from 2.8 to 2.1 m s -1 as windbreak distances narrowed from 90 to 6 m. As a consequence, potential evaporation declined by 15% and the amount of windblown soil particles by 50% in ridged and by 70% in flat treatments. Despite reduced potential evaporation, average subsoil water reserves were 14 mm smaller in the 6- than in the 20-m windbreak spacing indicating excessive water extraction by the windbreak vegetation. Thus, establishing windbreaks with natural savannah vegetation may require a careful consideration of the agronomic benefits and costs to competing crops. 21 refs., 5 figs

Mapping wind erosion hazard in Australia using MODIS-derived ground cover, soil moisture and climate data

International Nuclear Information System (INIS)

Yang, X; Leys, J

2014-01-01

This paper describes spatial modeling methods to identify wind erosion hazard (WEH) areas across Australia using the recently available time-series products of satellite-derived ground cover, soil moisture and wind speed. We implemented the approach and data sets in a geographic information system to produce WEH maps for Australia at 500 m ground resolution on a monthly basis for the recent thirteen year period (2000–2012). These maps reveal the significant wind erosion hazard areas and their dynamic tendencies at paddock and regional scales. Dust measurements from the DustWatch network were used to validate the model and interpret the dust source areas. The modeled hazard areas and changes were compared with results from a rule-set approach and the Computational Environmental Management System (CEMSYS) model. The study demonstrates that the time series products of ground cover, soil moisture and wind speed can be jointly used to identify landscape erodibility and to map seasonal changes of wind erosion hazard across Australia. The time series wind erosion hazard maps provide detailed and useful information to assist in better targeting areas for investments and continuous monitoring, evaluation and reporting that will lead to reduced wind erosion and improved soil condition

Dryland Degradation by wind erosion and its control

NARCIS (Netherlands)

Sterk, G.; Riksen, M.; Goossens, D.

2001-01-01

Global population growth, is expected to impose an increasing pressure on agricultural production in the world's drylands, which cover approximately 41␘f the continental area. The land resources in drylands are severely threatened by soil degradation, with wind erosion being, one of the major

Wind born(e) landscapes: the role of wind erosion in agricultural land management and nature development

NARCIS (Netherlands)

Riksen, M.J.P.M.

2006-01-01

Wind has played an important role in the geological development of the north-western Europe. Various aeolian deposits such as inland dunes, river dunes, cover sands, drift sands and coastal dunes, form the base of large areas in our present landscape. The role of wind erosion in today's north-west

Implications of climate change on wind erosion of agricultural lands in the Columbia plateau

Directory of Open Access Journals (Sweden)

B.S. Sharratt

2015-12-01

Full Text Available Climate change may impact soil health and productivity as a result of accelerated or decelerated rates of erosion. Previous studies suggest a greater risk of wind erosion on arid and semi-arid lands due to loss of biomass under a future warmer climate. There have been no studies conducted to assess the impact of climate change on wind erosion in the Columbia Plateau of the Pacific Northwest United States where wind erosion of agricultural lands can cause exceedance of national air quality standards. The Wind Erosion Prediction System (WEPS was used to assess wind erosion and PM10 (particulate matter ≤10 µm in aerodynamic diameter emissions under a future climate projected by downscaling 18 Global Climate Models (GCM for a conservative emissions pathway. Wind erosion simulations were conducted at Lacrosse and Lind, WA and Moro, OR on a winter wheat-summer fallow (WW-SF rotation and at Lind on an additional winter wheat-camelina-summer fallow (WW-Cam-SF rotation. Each rotation was subject to conservation or conventional tillage practices for a baseline (1970–1999 and mid-21st century climate (2035–2064. A significant increase in temperature and nominal increases in precipitation were projected by an ensemble of climate models for the Columbia Plateau by the mid-21st century. Soil and PM10 losses were 25–84% lower for a mid-21st century climate, due in part to greater biomass production associated with CO2 fertilization and warmer temperatures. The reduction in soil and PM10 loss is projected to be more apparent for conservation tillage practices in the future. Soil and PM10 losses were greater from a WW-Cam-SF rotation than WW-SF rotation when conservation tillage practices were employed during the fallow phase of the rotations. Despite accounting for differences in the length of each rotation, annual soil and PM10 losses remained higher for the WW-Cam-SF rotation than the WW-SF rotation. Soil and PM10 losses were more variable across

Wind erosion on Deliblato (the largest European continental sandy terrain) studied using 210Pbex and 137Cs measurements

International Nuclear Information System (INIS)

Krmar, M.; Hansman, J.; Todorovic, N.; Mihailovic, A.; Vucinic-Vasic, M.; Savic, R.

2015-01-01

The objective of this paper is to estimate the difference in wind erosion between two extreme situations: sandy soil permanently covered by grass and the nearby frequently ploughed area highly susceptible to wind erosion. The spatial pattern of soil erosion rate was investigated using 137 Cs and 210 Pb ex tracing technique. The spatial pattern of erosion rate obtained within the studied area reveal influence of topography as well as direction of prevailing winds on mobilization and transport of the soil particles. (author)

Wind erosion of waste impoundments in arid climates and mitigation of dust pollution.

Science.gov (United States)

Blight, G E

2008-12-01

Wind can erode and disperse fine-grained material from an impoundment of mining, industrial or municipal waste that stands above the level of its surroundings. Such dust dispersion can be a serious nuisance as well as a health hazard to inhabitants and animals in nearby settlements. It can also degrade crops, making them less marketable, and pollute soil, surface water and ground water. Wind can seasonally erode waste impoundments in all types of climate, but the erosion intensifies and persists for more of each year as regional aridity increases. As clouds of dust are often observed billowing across the top surfaces of waste impoundments in dry windy weather, there is a common misconception that dust arises from erosion of the top surface of an impoundment, resulting in much effort and money being misspent on top treatments when in fact the sloped sides of the impoundments are the true source of blown dust. This paper offers a brief review of general waste impoundment wind erosion issues and then focuses in more detail on the mechanics of how wind erodes surfaces of waste impoundments. Recommendations are offered for mitigating the effects of wind-eroded dust.

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

International Nuclear Information System (INIS)

Garcia Fernandez, G.; Romero Diaz, A.

2009-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

Garcia Fernandez, G.; Romero Diaz, A.

2009-07-01

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

Literature review of models for estimating soil erosion and deposition from wind stresses on uranium-mill-tailings covers

International Nuclear Information System (INIS)

Bander, T.J.

1982-11-01

Pacific Northwest Laboratory (PNL) is investigating the use of a rock armoring blanket (riprap) to mitigate wind and water erosion of an earthen radon-suppression cover applied to uranium-mill tailings. The mechanics of wind erosion, as well as of soil deposition, are discussed in this report. Several wind erosion models are reviewed to determine if they can be used to estimate the erosion of soil from a mill-tailings cover. One model, developed by W.S. Chepil, contains the most-important factors that describe variables that influence wind erosion. Particular features of other models are also discussed, as well as the application of Chepil's model to a particular tailings pile. For this particular tailings pile, the estimated erosion was almost one inch per year for an unprotected tailings soil surface. Wide variability in the deposition velocity and lack of adequate deposition models preclude reliable estimates of the rate at which airborne particles are deposited

Literature review of models for estimating soil erosion and deposition from wind stresses on uranium-mill-tailings covers

Energy Technology Data Exchange (ETDEWEB)

Bander, T.J.

1982-11-01

Pacific Northwest Laboratory (PNL) is investigating the use of a rock armoring blanket (riprap) to mitigate wind and water erosion of an earthen radon-suppression cover applied to uranium-mill tailings. The mechanics of wind erosion, as well as of soil deposition, are discussed in this report. Several wind erosion models are reviewed to determine if they can be used to estimate the erosion of soil from a mill-tailings cover. One model, developed by W.S. Chepil, contains the most-important factors that describe variables that influence wind erosion. Particular features of other models are also discussed, as well as the application of Chepil's model to a particular tailings pile. For this particular tailings pile, the estimated erosion was almost one inch per year for an unprotected tailings soil surface. Wide variability in the deposition velocity and lack of adequate deposition models preclude reliable estimates of the rate at which airborne particles are deposited.

A history of wind erosion prediction models in the United States Department of Agriculture Prior to the Wind Erosion Prediction System

Science.gov (United States)

The Great Plains experienced an influx of settlers in the late 1850s to 1900. Periodic drought was hard on both settlers and the soil and caused severe wind erosion. The period known as the Dirty Thirties, 1931 to 1939, produced many severe windstorms, and the resulting dusty sky over Washington, D....

Crop production and economic loss due to wind erosion in hot arid ecosystem of India

Science.gov (United States)

Santra, Priyabrata; Moharana, P. C.; Kumar, Mahesh; Soni, M. L.; Pandey, C. B.; Chaudhari, S. K.; Sikka, A. K.

2017-10-01

Wind erosion is a severe land degradation process in hot arid western India and affects the agricultural production system. It affects crop yield directly by damaging the crops through abrasion, burial, dust deposition etc. and indirectly by reducing soil fertility. In this study, an attempt was made to quantify the indirect impact of wind erosion process on crop production loss and associated economic loss in hot arid ecosystem of India. It has been observed that soil loss due to wind erosion varies from minimum 1.3 t ha-1 to maximum 83.3 t ha-1 as per the severity. Yield loss due to wind erosion was found maximum for groundnut (Arachis hypogea) (5-331 kg ha-1 yr-1), whereas minimum for moth bean (Vigna aconitifolia) (1-93 kg ha-1 yr-1). For pearl millet (Pennisetum glaucum), which covers a major portion of arable lands in western Rajasthan, the yield loss was found 3-195 kg ha-1 yr-1. Economic loss was found higher for groundnut and clusterbean (Cyamopsis tetragonoloba) than rest crops, which are about

Wind erosion research at an uranium mill tailings site

International Nuclear Information System (INIS)

Sehmel, G.A.

1977-07-01

A uranium mill tailings pile at Grants, New Mexico, was selected for wind erosion research since the configuration provides flat area containing fine sand and made up of larger particles. The wind erosion experiment is discussed. Experimental equipment consists of meteorological instrumentation to automatically activate air samplers as a function of wind speed increments and direction, particle cascade impactors to measure airborne respirable concentrations as a function of particle size, inertial impaction devices to measure nonrespirable fluxes of airborne particles, a virtual particle cascade impactor to measure airborne concentrations of toxic trace elements, and soil depth gauges to measure changes in surface soil elevations as a function of time. Both radioactive particles as well as toxic trace element concentrations are measured. Radioactive particles are measured with both particle cascade impactors as well as high-volume air samplers. In contrast, toxic trace element airborne concentrations are measured only with a two-stage virtual particle cascade impactor. Fluxes of nonrespirable airborne particles are measured with inertial impaction devices. At particle cascade impactor sites, a rotating cyclone preseparator collects nonrespirable particles. In addition at all sites, fluxes of nonrespirable particles are measured using an open cavity inertial impaction device

Ice-Release and Erosion Resistant Materials for Wind Turbines

Science.gov (United States)

Zhang, Wei; Brinn, Cameron; Cook, Alex; Pascual-Marquez, Fernando

2017-11-01

Icing conditions may cause wind turbine generators to partially lose productivity or to be completely shut down to avoid structural damage. At present, commercially available technologies to mitigate this problem consist of expensive, energy hungry heating elements, which costs roughly 70,000 euro per medium size turbine. Conventional passive ice protection coating systems heavily rely on delicate surface structures and expensive materials to create water repellent superhydrophobic / low surface energy surfaces, which have been proven to be ineffective against ice accumulation. The lack of performance among conventional ice protection materials stems from a flaw in the approach to the problem: failure to recognize that water in its liquid form (WATER) and water in its solid form (ICE) are two different things. Something that works for WATER does not automatically work for ICE. Another reason is that many superhydrophobic materials are often reliant upon often fragile micro-structured surfaces to achieve their intended effects. This paper discusses a fundamentally different approach to the creation of a robust, low cost, durable, and multifunctional materials for ice release and erosion resistance. This National Science Foundation sponsored ice-release coating technology holds promise for protecting wind turbine blades and towers, thus potentially increasing reliability for power generation under icing conditions. Because of the vulnerability of wind turbine blades to ice buildup and erosion damages, wind farm facilities stand to reap considerable benefits.

Spatial evolution equation of wind wave growth

Institute of Scientific and Technical Information of China (English)

WANG; Wei; (王; 伟); SUN; Fu; (孙; 孚); DAI; Dejun; (戴德君)

2003-01-01

Based on the dynamic essence of air-sea interactions, a feedback type of spatial evolution equation is suggested to match reasonably the growing process of wind waves. This simple equation involving the dominant factors of wind wave growth is able to explain the transfer of energy from high to low frequencies without introducing the concept of nonlinear wave-wave interactions, and the results agree well with observations. The rate of wave height growth derived in this dissertation is applicable to both laboratory and open sea, which solidifies the physical basis of using laboratory experiments to investigate the generation of wind waves. Thus the proposed spatial evolution equation provides a new approach for the research on dynamic mechanism of air-sea interactions and wind wave prediction.

Using Cesium-137 technique to study the characteristics of different aspect of soil erosion in the Wind-water Erosion Crisscross Region on Loess Plateau of China

International Nuclear Information System (INIS)

Li Mian; Li Zhanbin; Liu Puling; Yao Wenyi

2005-01-01

The most serious soil erosion on Loess Plateau exists in the Wind-water Erosion Crisscross Region. In the past 20 years, the types and intensity of soil erosion and its temporal and spatial distribution were studied, but studies on the difference of soil erosion between slope aspects and slope positions in this area have no report. However, it is very important to analyze and evaluate quantitatively the characteristics of different aspects and positions of soil loss for the prevention and treatment of soil erosion in this area. The spatial pattern of net soil loss on 4 downslope transects in four aspects (east, west, south and north) on a typical Mao (round loess mound) in Liudaogou catchment in Wind-water Erosion Crisscross Region was measured in 2000 using the resident cesium-137 deficit technique. The purposes of this investigation were undertaken to determine whether or not 137 Cs measurement would give a useful indication of the extent of soil loss and their characteristics from cultivated hillsides in different slope aspect and slope position in the study area. The results showed that the difference of soil erosion in different aspect was significant and the erosion rate was in this order: north>east>south>west. Compared with other areas, the difference of erosion rate between north hillside and south hillside was on the contrary, and the possible explanations could be the effect of wind erosion. Also, the percentage of wind erosion was estimated to be at least larger than 18% of total soil loss by comparing the difference of erosion amount in south hillside and north hillside. The erosion rates on different slope positions in all aspects were also different, the highest net soil loss occurred in the lower slope position, and the upper and middle slope positions were slight. The general trend of net soil loss on sloping surface was to increase in fluctuation with increasing downslope distance

Using Cesium-137 technique to study the characteristics of different aspect of soil erosion in the Wind-water Erosion Crisscross Region on Loess Plateau of China

Energy Technology Data Exchange (ETDEWEB)

Li Mian E-mail: hnli-mian@163.com; Li Zhanbin; Liu Puling; Yao Wenyi

2005-01-01

The most serious soil erosion on Loess Plateau exists in the Wind-water Erosion Crisscross Region. In the past 20 years, the types and intensity of soil erosion and its temporal and spatial distribution were studied, but studies on the difference of soil erosion between slope aspects and slope positions in this area have no report. However, it is very important to analyze and evaluate quantitatively the characteristics of different aspects and positions of soil loss for the prevention and treatment of soil erosion in this area. The spatial pattern of net soil loss on 4 downslope transects in four aspects (east, west, south and north) on a typical Mao (round loess mound) in Liudaogou catchment in Wind-water Erosion Crisscross Region was measured in 2000 using the resident cesium-137 deficit technique. The purposes of this investigation were undertaken to determine whether or not {sup 137}Cs measurement would give a useful indication of the extent of soil loss and their characteristics from cultivated hillsides in different slope aspect and slope position in the study area. The results showed that the difference of soil erosion in different aspect was significant and the erosion rate was in this order: north>east>south>west. Compared with other areas, the difference of erosion rate between north hillside and south hillside was on the contrary, and the possible explanations could be the effect of wind erosion. Also, the percentage of wind erosion was estimated to be at least larger than 18% of total soil loss by comparing the difference of erosion amount in south hillside and north hillside. The erosion rates on different slope positions in all aspects were also different, the highest net soil loss occurred in the lower slope position, and the upper and middle slope positions were slight. The general trend of net soil loss on sloping surface was to increase in fluctuation with increasing downslope distance.

Evaluation of chemical stabilizers and windscreens for wind erosion control of uranium mill tailings

International Nuclear Information System (INIS)

Elmore, M.R.; Hartley, J.N.

1984-08-01

Potential wind erosion of uranium mill tailings is a concern for the surface disposal of tailings at uranium mills. Wind-blown tailings may subsequently be redeposited on areas outside the impoundment. Pacific Northwest Laboratory (PNL) is investigating techniques for fugitive dust control at uranium mill tailings piles. Laboratory tests, including wind tunnel studies, were conducted to evaluate the relative effectiveness of 43 chemical stabilizers. Seventeen of the more promising stabilizers were applied to test plots on a uranium tailings pile at the American Nuclear Corporation-Gas Hills Project mill site in central Wyoming. The durabilities of these materials under actual site conditions were evaluated over time. In addition, field testing of commercially available windscreens was conducted. Test panels were constructed of eight different materials at the Wyoming test site to compare their durability. A second test site was established near PNL to evaluate the effectiveness of windscreens at reducing wind velocity, and thereby reduce the potential for wind erosion of mill tailings. Results of the laboratory land field tests of the chemical stabilizers and windscreens are presented, along with costs versus effectiveness of these techniques for control of wind erosion at mill tailings piles. 12 references, 4 figures, 6 tables

Leading edge erosion of coated wind turbine blades: Review of coating life models

NARCIS (Netherlands)

Slot, H.M.; Gelinck, E.R.M.; Rentrop, A.; van der Heide, Emile

2015-01-01

Erosion of the leading edge of wind turbine blades by droplet impingement wear, reduces blade aerodynamic efficiency and power output. Eventually, it compromises the integrity of blade surfaces. Elastomeric coatings are currently used for erosion resistance, yet the life of such coatings cannot be

Dust emission and soil loss due to anthropogenic activities by wind erosion simulations

Science.gov (United States)

Katra, Itzhak; Swet, Nitzan; Tanner, Smadar

2017-04-01

Wind erosion is major process of soil loss and air pollution by dust emission of clays, nutrients, and microorganisms. Many soils throughout the world are currently or potentially associated with dust emissions, especially in dryland zones. The research focuses on wind erosion in semi-arid soils (Northern Negev, Israel) that are subjected to increased human activities of urban development and agriculture. A boundary-layer wind tunnel has been used to study dust emission and soil loss by simulation and quantification of high-resolution wind processes. Field experiments were conducted in various surface types of dry loess soils. The experimental plots represent soils with long-term and short term influences of land uses such as agriculture (conventional and organic practices), grazing, and natural preserves. The wind tunnel was operated under various wind velocities that are above the threshold velocity of aeolian erosion. Total soil sediment and particulate matter (PM) fluxes were calculated. Topsoil samples from the experimental plots were analysed in the laboratory for physical and chemical characteristics including aggregation, organic matter, and high-resolution particle size distribution. The results showed variations in dust emission in response to surface types and winds to provide quantitative estimates of soil loss over time. Substantial loss of particulate matter that is < 10 micrometer in diameter, including clays and nutrients, was recorded in most experimental conditions. Integrative analyses of the topsoil properties and dust experiment highlight the significant implications for soil nutrient resources and management strategies as well as for PM loading to the atmosphere and air pollution.

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

Science.gov (United States)

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

2014-01-01

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

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

Science.gov (United States)

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

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

An index guiding temporal planting policies for wind erosion reduction

NARCIS (Netherlands)

Zhao, C.X.; Zheng, D.W.; Stigter, C.J.; He, W.Q.; Tuo, D.B.; Zhao, P.

2006-01-01

Vegetation cover has spatial as well as temporal characteristics, but the latter are often neglected. Temporal cover characteristics were explored to recommend planting policies for returning arable land into land better protected from serious wind erosion during late autumn, winter, and

Remote sensing of land use/cover changes and its effect on wind erosion potential in southern Iran

NARCIS (Netherlands)

Rezaei, Mahrooz; Sameni, Abdolmajid; Fallah Shamsi, Seyed Rashid; Bartholomeus, Harm

2016-01-01

Wind erosion is a complex process influenced by different factors. Most of these factors are stable over time, but land use/cover and land management practices are changing gradually. Therefore, this research investigates the impact of changing land use/cover and land management on wind erosion

Manufacturing issues which affect coating erosion performance in wind turbine blades

Science.gov (United States)

Cortés, E.; Sánchez, F.; Domenech, L.; Olivares, A.; Young, T. M.; O'Carroll, A.; Chinesta, F.

2017-10-01

Erosion damage, caused by repeated rain droplet impact on the leading edges of wind turbine blades, is a major cause for cost concern. Resin Infusion (RI) is used in wind energy blades where low weight and high mechanical performance materials are demanded. The surface coating plays a crucial role in the manufacturing and performance response. The Leading Edge coating is usually moulded, painted or sprayed onto the blade surface so adequate adhesion in the layers' characterization through the thickness is required for mechanical performance and durability reasons. In the current work, an investigation has been directed into the resulting rain erosion durability of the coating was undertaken through a combination of mass loss testing measurements with manufacturing processing parameter variations. The adhesion and erosion is affected by the shock wave caused by the collapsing water droplet on impact. The stress waves are transmitted to the substrate, so microestructural discontinuities in coating layers and interfaces play a key role on its degradation. Standard industrial systems are based on a multilayer system, with a high number of interfaces that tend to accelerate erosion by delamination. Analytical and numerical models are commonly used to relate lifetime prediction and to identify suitable coating and composite substrate combinations and their potential stress reduction on the interface. In this research, the input parameters for the appropriate definition of the Cohesive Zone Modelling (CZM) of the coating-substrate interface are outlined by means of Pull off testing and Peeling testing results. It allowed one to optimize manufacturing and coating process for blades into a knowledge-based guidance for leading edge coating material development. It was achieved by investigating the erosion degradation process using both numerical and laboratory techniques (Pull off, Peeling and Rain Erosion Testing in a whirling arm rain erosion test facility).

Wind erosion potential influenced by tillage in an irrigated potato-sweet corn rotation in the Columbia Basin

Science.gov (United States)

Wind erosion is a concern within the Columbia Basin of the Inland Pacific Northwest (PNW) United States due to the sandy texture of soils and small amount of residue retained on the soil surface after harvest of vegetable crops like potato. This study assessed potential wind erosion of an irrigated ...

Application of fuzzy logic approach for wind erosion hazard mapping in Laghouat region (Algeria) using remote sensing and GIS

Science.gov (United States)

Saadoud, Djouher; Hassani, Mohamed; Martin Peinado, Francisco José; Guettouche, Mohamed Saïd

2018-06-01

Wind erosion is one of the most serious environmental problems in Algeria that threatens human activities and socio-economic development. The main goal of this study is to apply a fuzzy logic approach to wind erosion sensitivity mapping in the Laghouat region, Algeria. Six causative factors, obtained by applying fuzzy membership functions to each used parameter, are considered: soil, vegetation cover, wind factor, soil dryness, land topography and land cover sensitivity. Different fuzzy operators (AND, OR, SUM, PRODUCT, and GAMMA) are applied to generate wind-erosion hazard map. Success rate curves reveal that the fuzzy gamma (γ) operator, with γ equal to 0.9, gives the best prediction accuracy with an area under curve of 85.2%. The resulting wind-erosion sensitivity map delineates the area into different zones of five relative sensitivity classes: very high, high, moderate, low and very low. The estimated result was verified by field measurements and the high statistically significant value of a chi-square test.

Wind Erosion Caused by Land Use Changes Significantly Reduces Ecosystem Carbon Storage and Carbon Sequestration Potentials in Grassland

Science.gov (United States)

Li, P.; Chi, Y. G.; Wang, J.; Liu, L.

2017-12-01

Wind erosion exerts a fundamental influence on the biotic and abiotic processes associated with ecosystem carbon (C) cycle. However, how wind erosion under different land use scenarios will affect ecosystem C balance and its capacity for future C sequestration are poorly quantified. Here, we established an experiment in a temperate steppe in Inner Mongolia, and simulated different intensity of land uses: control, 50% of aboveground vegetation removal (50R), 100% vegetation removal (100R) and tillage (TI). We monitored lateral and vertical carbon flux components and soil characteristics from 2013 to 2016. Our study reveals three key findings relating to the driving factors, the magnitude and consequence of wind erosion on ecosystem C balance: (1) Frequency of heavy wind exerts a fundamental control over the severity of soil erosion, and its interaction with precipitation and vegetation characteristics explained 69% variation in erosion intensity. (2) With increases in land use intensity, the lateral C flux induced by wind erosion increased rapidly, equivalent to 33%, 86%, 111% and 183% of the net ecosystem exchange of the control site under control, 50R, 100R and TI sites, respectively. (3) After three years' treatment, erosion induced decrease in fine fractions led to 31%, 43%, 85% of permanent loss of C sequestration potential in the surface 5cm soil for 50R, 100R and TI sites. Overall, our study demonstrates that lateral C flux associated with wind erosion is too large to be ignored. The loss of C-enriched fine particles not only reduces current ecosystem C content, but also results in irreversible loss of future soil C sequestration potential. The dynamic soil characteristics need be considered when projecting future ecosystem C balance in aeolian landscape. We also propose that to maintain the sustainability of grassland ecosystems, land managers should focus on implementing appropriate land use rather than rely on subsequent managements on degraded soils.

A combined CFD-experimental method for developing an erosion equation for both gas-sand and liquid-sand flows

Science.gov (United States)

Mansouri, Amir

The surface degradation of equipment due to consecutive impacts of abrasive particles carried by fluid flow is called solid particle erosion. Solid particle erosion occurs in many industries including oil and gas. In order to prevent abrupt failures and costly repairs, it is essential to predict the erosion rate and identify the locations of the equipment that are mostly at risk. Computational Fluid Dynamics (CFD) is a powerful tool for predicting the erosion rate. Erosion prediction using CFD analysis includes three steps: (1) obtaining flow solution, (2) particle tracking and calculating the particle impact speed and angle, and (3) relating the particle impact information to mass loss of material through an erosion equation. Erosion equations are commonly generated using dry impingement jet tests (sand-air), since the particle impact speed and angle are assumed not to deviate from conditions in the jet. However, in slurry flows, a wide range of particle impact speeds and angles are produced in a single slurry jet test with liquid and sand particles. In this study, a novel and combined CFD/experimental method for developing an erosion equation in slurry flows is presented. In this method, a CFD analysis is used to characterize the particle impact speed, angle, and impact rate at specific locations on the test sample. Then, the particle impact data are related to the measured erosion depth to achieve an erosion equation from submerged testing. Traditionally, it was assumed that the erosion equation developed based on gas testing can be used for both gas-sand and liquid-sand flows. The erosion equations developed in this work were implemented in a CFD code, and CFD predictions were validated for various test conditions. It was shown that the erosion equation developed based on slurry tests can significantly improve the local thickness loss prediction in slurry flows. Finally, a generalized erosion equation is proposed which can be used to predict the erosion rate in

PM2.5 and PM10 Emission from agricultural soils by wind erosion

Science.gov (United States)

Soil tillage and wind erosion are a major source of particulate matter less than 2.5 and 10 µm (PM2.5 and PM10) emission from cultivated soil. Fifteen cultivated soils collected from 5 states were tested as crushed (<2.0 mm) and uncrushed (natural aggregation) at 8, 10, and 13 m s-1 wind velocity in...

The combined effect of wind and rain on interrill erosion processes

International Nuclear Information System (INIS)

Erpul, G.; Gabriels, D.; Norton, L.D.

2004-01-01

flow-driven process begins to transport the detached soil particles. This is different from the approach of recent interrill erosion models that soil detached by the rain splash will be subsequently transported by overland flow. The results of the study showed that, when compared to the contribution of the flow-driven transport, the contribution of the rain splash transport was significant to the extent that it should not be neglected in accurately predicting water erosion from interrill areas under wind-driven rains

[Estimation of the effect derived from wind erosion of soil and dust emission in Tianjin suburbs on the central district based on WEPS model].

Science.gov (United States)

Chen, Li; Han, Ting-Ting; Li, Tao; Ji, Ya-Qin; Bai, Zhi-Peng; Wang, Bin

2012-07-01

Due to the lack of a prediction model for current wind erosion in China and the slow development for such models, this study aims to predict the wind erosion of soil and the dust emission and develop a prediction model for wind erosion in Tianjin by investigating the structure, parameter systems and the relationships among the parameter systems of the prediction models for wind erosion in typical areas, using the U.S. wind erosion prediction system (WEPS) as reference. Based on the remote sensing technique and the test data, a parameter system was established for the prediction model of wind erosion and dust emission, and a model was developed that was suitable for the prediction of wind erosion and dust emission in Tianjin. Tianjin was divided into 11 080 blocks with a resolution of 1 x 1 km2, among which 7 778 dust emitting blocks were selected. The parameters of the blocks were localized, including longitude, latitude, elevation and direction, etc.. The database files of blocks were localized, including wind file, climate file, soil file and management file. The weps. run file was edited. Based on Microsoft Visualstudio 2008, secondary development was done using C + + language, and the dust fluxes of 7 778 blocks were estimated, including creep and saltation fluxes, suspension fluxes and PM10 fluxes. Based on the parameters of wind tunnel experiments in Inner Mongolia, the soil measurement data and climate data in suburbs of Tianjin, the wind erosion module, wind erosion fluxes, dust emission release modulus and dust release fluxes were calculated for the four seasons and the whole year in suburbs of Tianjin. In 2009, the total creep and saltation fluxes, suspension fluxes and PM10 fluxes in the suburbs of Tianjin were 2.54 x 10(6) t, 1.25 x 10(7) t and 9.04 x 10(5) t, respectively, among which, the parts pointing to the central district were 5.61 x 10(5) t, 2.89 x 10(6) t and 2.03 x 10(5) t, respectively.

The National Wind Erosion Research Network: Building a standardized long-term data resource for aeolian research, modeling and land management

Science.gov (United States)

Webb, Nicholas P.; Herrick, Jeffrey E.; Van Zee, Justin W; Courtright, Ericha M; Hugenholtz, Ted M; Zobeck, Ted M; Okin, Gregory S.; Barchyn, Thomas E; Billings, Benjamin J; Boyd, Robert A.; Clingan, Scott D; Cooper, Brad F; Duniway, Michael C.; Derner, Justin D.; Fox, Fred A; Havstad, Kris M.; Heilman, Philip; LaPlante, Valerie; Ludwig, Noel A; Metz, Loretta J; Nearing, Mark A; Norfleet, M Lee; Pierson, Frederick B; Sanderson, Matt A; Sharrat, Brenton S; Steiner, Jean L; Tatarko, John; Tedela, Negussie H; Todelo, David; Unnasch, Robert S; Van Pelt, R Scott; Wagner, Larry

2016-01-01

The National Wind Erosion Research Network was established in 2014 as a collaborative effort led by the United States Department of Agriculture’s Agricultural Research Service and Natural Resources Conservation Service, and the United States Department of the Interior’s Bureau of Land Management, to address the need for a long-term research program to meet critical challenges in wind erosion research and management in the United States. The Network has three aims: (1) provide data to support understanding of basic aeolian processes across land use types, land cover types, and management practices, (2) support development and application of models to assess wind erosion and dust emission and their impacts on human and environmental systems, and (3) encourage collaboration among the aeolian research community and resource managers for the transfer of wind erosion technologies. The Network currently consists of thirteen intensively instrumented sites providing measurements of aeolian sediment transport rates, meteorological conditions, and soil and vegetation properties that influence wind erosion. Network sites are located across rangelands, croplands, and deserts of the western US. In support of Network activities, http://winderosionnetwork.org was developed as a portal for information about the Network, providing site descriptions, measurement protocols, and data visualization tools to facilitate collaboration with scientists and managers interested in the Network and accessing Network products. The Network provides a mechanism for engaging national and international partners in a wind erosion research program that addresses the need for improved understanding and prediction of aeolian processes across complex and diverse land use types and management practices.

Soil drying and wind erosion as affected by different types of shelterbelts planted in the desert region of western Rajasthan, India

Energy Technology Data Exchange (ETDEWEB)

Gupta, J.P.; Rao, G.G.S.N.; Gupta, G.N.; Rao, B.V.R.

1983-03-01

Studies on the effects of 8-year-old shelterbelt plantations indicate a general reduction in wind velocity, wind erosion and evaporative loss of moisture from fields protected with Prosopis juliflora, Cassia siamea and Acacia tortilis. Cassia siamea shelterbelts are the most effective in checking wind erosion and delaying drying of the soil. (Refs. 13).

Study of calibration equations of 137Cs methodology for soil erosion determination

International Nuclear Information System (INIS)

Santos, Elias Antunes dos

2001-02-01

Using the method of 137 Cs and gamma-ray spectrometry, soil samples of two plots erosion were studied at Londrina city. the soil class studied was a dystrophic dark red soil (LRd), with erosion indexes measured by Agronomic Institute of Parana State (IAPAR) using a conventional method, since 1976. Through the percentage reduction of 137 Cs related to the reference site, the soil losses were calculated using the proportional, mass balance and profile distribution models. Making the correlation between the 137 Cs concentrations and the erosion measured by IAPAR, two calibration equations were obtained and applied to the data set measured in the basin of the Unda river and compared to those models in the literature. As reference region, was chosen a natural forest located close to the plots. The average inventory of 137 Cs was 555± 16 Bq.m -2 . The inventories of the erosion plots varied from 112 to 136 Bq.m -2 for samples collected until 30 cm depth. The erosion rates estimated by the models varied from 64 to 85 ton.ha -1 .yr -1 for the proportional and profile distribution models, respectively, and 137 to 165 ton.ha -1 for the mass balance model, while the measured erosion obtained by IAPAR was 86 ton.ha -1 .yr -1 . From the two calibration equations obtained, the one that take into account the 137 Cs distribution with the soil profile was that showed the best consistence with the erosion rated for the basin of the Unda river (same soil class) in the range from 4 to 48 ton.ha -1 .yr -1 , while the proportional and profile distribution models applied rates from 7 to 45 ton.ha -1 .yr -1 and 6 to 69 ton.ha -1 .yr -1 , respectively. (author)

Erosivity factor in the Universal Soil Loss Equation estimated from Finnish rainfall data

Directory of Open Access Journals (Sweden)

Maximilian Posch

1993-07-01

Full Text Available Continuous rainfall data recorded for many years at 8 stations in Finland were used to estimate rainfall erosivity, a quantity needed for soil loss predictions with the Universal Soil Loss Equation (USLE. The obtained erosivity values were then used to determine the 2 parameters of a power-law function describing the relationship between daily precipitation and erosivity. This function is of importance in erosion modeling at locations where no breakpoint rainfall data are available. The parameters of the power-law were estimated both by linear regression of the log-transformed data and by non-linear least-square fitting of the original data. Results indicate a considerable seasonal (monthly variation of the erosivity, whereas the spatial variation over Finland is rather small.

Agriculture’s Soil Conservation Programs Miss Full Potential in the Fight against Soil Erosion.

Science.gov (United States)

1983-11-28

Soil Loss Equation ( USLE ) and Wind Erosion Equation can be used with a reasonable degree of accuracy. It is the intention of ASCS to expand VC/SL to...HD-R37 495 AGRICULTURE’S SOIL CONSERVATION PROGRAMS MISS FULL i/i POTENTIAL IN THE FIGHT.(U) GENERAL ACCOUNTING OFFICE WASHINGTON DC RESOURCES...GENERAL Report To The Congress OF THE UNITED STATES Agriculture’s Soil Conservation Programs Miss Full Potential In The Fight Against Soil Erosion

7 CFR 610.12 - Equations for predicting soil loss due to water erosion.

Science.gov (United States)

2010-01-01

.... (a) The equation for predicting soil loss due to erosion for both the USLE and the RUSLE is A = R × K... 22161.) (b) The factors in the USLE equation are: (1) A is the estimation of average annual soil loss in... 7 Agriculture 6 2010-01-01 2010-01-01 false Equations for predicting soil loss due to water...

Generalized multidemensional propagation velocity equations for pool-boiling superconducting windings

International Nuclear Information System (INIS)

Christensen, E.H.; O'Loughlin, J.M.

1984-09-01

Several finite difference, finite element detailed analyses of propagation velocities in up to three dimensions in pool-boiling windings have been conducted for different electromagnetic and cryogenic environments. Likewise, a few full scale simulated winding and magnet tests have measured propagation velocities. These velocity data have been correlated in terms of winding thermophysical parameters. This analysis expresses longitudinal and transverse propagation velocities in the form of power function regression equations for a wide variety of windings and electromagnetic and thermohydraulic environments. The generalized velocity equations are considered applicable to well-ventilated, monolithic conductor windings. These design equations are used piecewise in a gross finite difference mode as functions of field to predict the rate of normal zone growth during quench conditions. A further check of the validity of these predictions is available through total predicted quench durations correlated with actual quench durations of large magnets

Interactive effects of moss-dominated crusts and Artemisia ordosica on wind erosion and soil moisture in Mu Us sandland, China.

Science.gov (United States)

Yang, Yongsheng; Bu, Chongfeng; Mu, Xingmin; Shao, Hongbo; Zhang, Kankan

2014-01-01

To better understand the effects of biological soil crusts (BSCs) on soil moisture and wind erosion and study the necessity and feasibility of disturbance of BSCs in the Mu Us sandland, the effects of four treatments, including moss-dominated crusts alone, Artemisia ordosica alone, bare sand, and Artemisia ordosica combined with moss-dominated crusts, on rainwater infiltration, soil moisture, and annual wind erosion were observed. The major results are as follows. (1) The development of moss-dominated crusts exacerbated soil moisture consumption and had negative effects on soil moisture in the Mu Us sandland. (2) Moss-dominated crusts significantly increased soil resistance to wind erosion, and when combined with Artemisia ordosica, this effect became more significant. The contribution of moss-dominated crusts under Artemisia ordosica was significantly lower than that of moss-dominated crusts alone in sites where vegetative coverage > 50%. (3) Finally, an appropriate disturbance of moss-dominated crusts in the rainy season in sites with high vegetative coverage improved soil water environment and vegetation succession, but disturbance in sites with little or no vegetative cover should be prohibited to avoid the exacerbation of wind erosion.

Sonic anemometry and sediment traps to evaluate the effectiveness of windbreaks in preventing wind erosion

Directory of Open Access Journals (Sweden)

Alejandro López

Full Text Available ABSTRACT The present work analyzes the effectiveness of windbreaks against wind erosion through the study of streamline patterns and turbulent flow by means of sonic anemometry and sediment traps. To this end, windbreaks composed of plastic meshes (7.5 m long and 0.7 m tall were used. Windbreaks are a good means to reduce wind erosion, as they produce a positive effect on the characteristics of air currents that are related to wind erosion processes. Due to their ease of installation and dismantling, plastic meshes are widely used in areas where they are not required permanently. In our study, the use of a mesh of 13 × 30 threads cm−2 and 39 % porosity resulted in an average reduction of 85 % in face velocity at a height of 0.4 m and a distance of 1 m from the windbreak. The turbulence intensity i increased behind the windbreak because the reduction of mean of air speed on the leeside caused by the flow of air through the windbreak. Fluctuation levels, however, remained stable. The mean values of turbulence kinetic energy k decreased by 65 % to 86 % at a distance of 1 m from the windbreak and at a height of 0.4 m. The windbreak reduces erosion and sediment transportation 2 m downwind (2.9 times the windbreak height. Nevertheless, sediment transportation was not reduced at a height of 1.0 m and the effect of the windbreak was not observed at a distance of 6 m downwind (8.6 m times the windbreak height.

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

Science.gov (United States)

Funk, Roger; Deumlich, Detlef; Völker, Lidia

2017-04-01

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

Retrospection of recent 30-year changes in the process of soil wind erosion in the Luanhe River Source Area of North China using Cesium-137

Energy Technology Data Exchange (ETDEWEB)

Chen Zhifan [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, 19 Xin Jie Kou Wai St., Beijing 100875 (China) and College of Environment and Planning, Henan University, Kaifeng 475001 (China)], E-mail: chenzhf0604@163.com; Zhao Ye [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, 19 Xin Jie Kou Wai St., Beijing 100875 (China)], E-mail: zhaoye@bnu.edu.cn; Qiao Jiejuan [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, 19 Xin Jie Kou Wai St., Beijing 100875 (China); Zhang Qing [National Institute for Radiological Protection, Chinese Center for Disease Control and Protection, Beijing 100088 (China); Zhu Yuen [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, 19 Xin Jie Kou Wai St., Beijing 100875 (China); Xu Cuihua [National Institute for Radiological Protection, Chinese Center for Disease Control and Protection, Beijing 100088 (China)

2009-10-15

The Luanhe River Source Area belongs to typical semi-arid, agro-pastoral ecotone of North China. It is very important for the prevention and treatment of soil erosion in North China to analyze and evaluate quantitatively the recent 30-year changes in the process of soil wind erosion in this area. Based on long field observations, soil samples from different depths in a representative wind-deposited soil profile in the Luanhe River Source Area were collected. Then the {sup 137}Cs activity of soil samples from different depths in the soil profile was determined using a GEM series HPGe (high-purity germanium) coaxial detector system (ADCAM-100), and their soil properties, such as the soil particle fraction and so on, were analyzed. According to the detected {sup 137}Cs activity of different depths, a continuous time sequence of the wind-deposited soil profile in the study area was established. Furthermore, through assumption on a soil relative wind erosion intensity index (SWEI), recent 30-year changes in the process of soil wind erosion in the Luanhe River Source Area were retrospected . The analysis results revealed that weaker soil wind erosion occurred in the study area from the 1970s to the early 1980s and from the late 1980s to the mid to late 1990s. Conversely, intense periods of soil wind erosion occurred in the mid-1980s and from the late 1990s to 2002.

Retrospection of recent 30-year changes in the process of soil wind erosion in the Luanhe River Source Area of North China using Cesium-137

International Nuclear Information System (INIS)

Chen Zhifan; Zhao Ye; Qiao Jiejuan; Zhang Qing; Zhu Yuen; Xu Cuihua

2009-01-01

The Luanhe River Source Area belongs to typical semi-arid, agro-pastoral ecotone of North China. It is very important for the prevention and treatment of soil erosion in North China to analyze and evaluate quantitatively the recent 30-year changes in the process of soil wind erosion in this area. Based on long field observations, soil samples from different depths in a representative wind-deposited soil profile in the Luanhe River Source Area were collected. Then the 137 Cs activity of soil samples from different depths in the soil profile was determined using a GEM series HPGe (high-purity germanium) coaxial detector system (ADCAM-100), and their soil properties, such as the soil particle fraction and so on, were analyzed. According to the detected 137 Cs activity of different depths, a continuous time sequence of the wind-deposited soil profile in the study area was established. Furthermore, through assumption on a soil relative wind erosion intensity index (SWEI), recent 30-year changes in the process of soil wind erosion in the Luanhe River Source Area were retrospected . The analysis results revealed that weaker soil wind erosion occurred in the study area from the 1970s to the early 1980s and from the late 1980s to the mid to late 1990s. Conversely, intense periods of soil wind erosion occurred in the mid-1980s and from the late 1990s to 2002.

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

Directory of Open Access Journals (Sweden)

Středová Hana

2015-06-01

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

Short-term Probabilistic Forecasting of Wind Speed Using Stochastic Differential Equations

DEFF Research Database (Denmark)

Iversen, Jan Emil Banning; Morales González, Juan Miguel; Møller, Jan Kloppenborg

2016-01-01

and uncertain nature. In this paper, we propose a modeling framework for wind speed that is based on stochastic differential equations. We show that stochastic differential equations allow us to naturally capture the time dependence structure of wind speed prediction errors (from 1 up to 24 hours ahead) and......It is widely accepted today that probabilistic forecasts of wind power production constitute valuable information for both wind power producers and power system operators to economically exploit this form of renewable energy, while mitigating the potential adverse effects related to its variable......, most importantly, to derive point and quantile forecasts, predictive distributions, and time-path trajectories (also referred to as scenarios or ensemble forecasts), all by one single stochastic differential equation model characterized by a few parameters....

Soil wind erosion in ecological olive trees in the Tabernas desert (southeastern Spain): a wind tunnel experiment

Science.gov (United States)

Asensio, Carlos; Lozano, Francisco Javier; Gallardo, Pedro; Giménez, Antonio

2016-08-01

Wind erosion is a key component of the soil degradation processes. The purpose of this study is to find out the influence of material loss from wind on soil properties for different soil types and changes in soil properties in olive groves when they are tilled. The study area is located in the north of the Tabernas Desert, in the province of Almería, southeastern Spain. It is one of the driest areas in Europe, with a semiarid thermo-Mediterranean type of climate. We used a new wind tunnel model over three different soil types (olive-cropped Calcisol, Cambisol and Luvisol) and studied micro-plot losses and deposits detected by an integrated laser scanner. We also studied the image processing possibilities for examining the particles attached to collector plates located at the end of the tunnel to determine their characteristics and whether they were applicable to the setup. Samples collected in the traps at the end of the tunnel were analyzed. We paid special attention to the influence of organic carbon, carbonate and clay contents because of their special impact on soil crusting and the wind-erodible fraction. A principal components analysis (PCA) was carried out to find any relations on generated dust properties and the intensity and behavior of those relationships. Component 1 separated data with high N and OC contents from samples high in fine silt, CO3= and available K content. Component 2 separated data with high coarse silt and clay contents from data with high fine sand content. Component 3 was an indicator of available P2O5 content. Analysis of variance (ANOVA) was carried out to analyze the effect of soil type and sampling height on different properties of trapped dust. Calculations based on tunnel data showed overestimation of erosion in soil types and calculation of the fraction of soil erodible by wind done by other authors for Spanish soils. As the highest loss was found in Cambisols, mainly due to the effect on soil crusting and the wind

A pan-European quantitative assessment of soil loss by wind

Science.gov (United States)

Borrelli, Pasqualle; Lugato, Emanuele; Panagos, Panos

2016-04-01

Soil erosion by wind is a serious environmental problem often low perceived but resulting in severe soil degradation forms. On the long-term a considerable part of topsoil - rich in nutrient and organic matters - could be removed compromising the agricultural productivity and inducing an increased use of fertilizers. Field scale studies and observations proven that wind erosion is a serious problem in many European sites. The state-of-the-art suggests a scenario where wind erosion locally affects the temperate climate areas of the northern European countries, as well as the semi-arid areas of the Mediterranean region. However, observations, field measurements and modelling assessments are extremely limited and unequally distributed across Europe. It implies a lack of knowledge about where and when wind erosion occurs, limiting policy actions aimed at mitigating land degradation. To gain a better understanding about soil degradation process, the Soil Resource Assessment working group of the Joint Research Centre carried out the first pan-European assessments of wind-erodible fraction of soil (EF) (Geoderma, 232, 471-478, 2014) and land susceptibility to wind erosion (Land Degradation & Development, DOI: 10.1002/ldr.2318). Today's challenge is to integrate the insights archived by these pan-European assessments, local experiments and field-scale models into a new generation of regional-scale wind erosion models. A GIS version of the Revised Wind Erosion Equation (RWEQ) was developed with the aim to i) move a step forward into the aforementioned challenges, and ii) evaluate the soil loss potential due to wind erosion in the agricoltural land of the EU. The model scheme was designed to describe daily soil loss potential, combining spatiotemporal conditions of soil erodibility, crust factor, soil moisture content, vegetation coverage and wind erosivity at 1 km2 resolution. The average soil loss predicted by GIS-RWEQ in the EU arable land ranges from 0 to 39.9 Mg ha-1 yr

An Assessment of the Impact of Urbanization on Soil Erosion in Inner Mongolia.

Science.gov (United States)

Wang, Li-Yan; Xiao, Yi; Rao, En-Ming; Jiang, Ling; Xiao, Yang; Ouyang, Zhi-Yun

2018-03-19

Inner Mongolia, an autonomous region of the People's Republic of China, has experienced severe soil erosion following a period of rapid economic development and urbanization. To investigate how urbanization has influenced the extent of soil erosion in Inner Mongolia, we used urbanization and soil erosion data from 2000 through 2010 to determine the relationship between urbanization and soil erosion patterns. Two empirical equations-the Revised Universal Soil Loss Equation (RUSLE) and the Revised Wind Erosion Equation (RWEQ)-were used to estimate the intensity of soil erosion, and we performed backward linear regression to model how it changed with greater urbanization. There was an apparent increase in the rate of urbanization and a decrease in the area affected by soil erosion in 2010 compared to the corresponding values for 2000. The urban population stood at 11.32 million in 2010, which represented a 16.47% increase over that in 2000. The area affected by soil erosion in 2000 totaled 704,817 km², yet it had decreased to 674,135 km² by 2010. However, a path of modest urban development (rural-urban mitigation) and reasonable industrial structuring (the development of GDP-2) may partially reduce urbanization's ecological pressure and thus indirectly reduce the threat of soil erosion to human security. Therefore, to better control soil erosion in Inner Mongolia during the process of urbanization, the current model of economic development should be modified to improve the eco-efficiency of urbanization, while also promoting new modes of urbanization that are environmentally sustainable, cost-effective, and conserve limited resources.

Evaluation of the 137Cs technique for estimating wind erosion losses for some sandy Western Australian soils

International Nuclear Information System (INIS)

Harper, R.J.; Gilkes, R.J.

1994-01-01

The utility of the caesium-137 technique, for estimating the effects of wind erosion, was evaluated on the soils of a semi-arid agricultural area near Jerramungup, Western Australia. The past incidence of wind erosion was estimated from field observations of soil profile morphology and an existing remote sensing study. Erosion was limited to sandy surfaced soils (0-4% clay), with a highly significant difference (P 137 Cs values between eroded and non-eroded sandy soils, with mean values of 243±17 and 386±13 Bq m -2 respectively. Non-eroded soils, with larger clay contents, had a mean 137 Cs content of 421±26 Bq m -2 , however, due to considerable variation between replicate samples, this value was not significantly different from that of the non-eroded sands. Hence, although the technique discriminates between eroded and non-eroded areas, the large variation in 137 Cs values means that from 27 to 96 replicate samples are required to provide statistically valid estimates of 137 Cs loss. The occurrence of around 18% of the total 137 Cs between 10 and 20 cm depth in these soils, despite cultivation being confined to the surface 9 cm, suggests that leaching of 137 Cs occurs in the sandy soils, although there was no relationship between clay content and 137 Cs value for either eroded or non-eroded soils. In a multiple linear regression, organic carbon content and the mean grain size of the eroded soils explained 35% of the variation in 137 Cs content. This relationship suggests that both organic carbon and 137 Cs are removed by erosion, with erosion being more prevalent on soils with a finer sand fraction. Clay and silt contents do not vary with depth in the near-surface horizons of the eroded sandy soils, hence it is likely that wind erosion strips the entire surface horizon with its 137 Cs content, rather than selectively winnowing fine material. 71 refs., 6 tabs., 2 fig

Climatological changing effects on wind, precipitation and erosion: Large, meso and small scale analysis

International Nuclear Information System (INIS)

Aslan, Z.

2004-01-01

The Fourier transformation analysis for monthly average values of meteorological parameters has been considered, and amplitudes, phase angles have been calculated by using ground measurements in Turkey. The first order harmonics of meteorological parameters show large scale effects, while higher order harmonics show the effects of small scale fluctuations. The variations of first through sixth order harmonic amplitudes and phases provide a useful means of understanding the large and local scale effects on meteorological parameters. The phase angle can be used to determine the time of year the maximum or minimum of a given harmonic occurs. The analysis helps us to distinguish different pressure, relative humidity, temperature, precipitation and wind speed regimes and transition regions. Local and large scale phenomenon and some unusual seasonal patterns are also defined near Keban Dam and the irrigation area. Analysis of precipitation based on long term data shows that semi-annual fluctuations are predominant in the study area. Similarly, pressure variations are mostly influenced by semi-annual fluctuations. Temperature and humidity variations are mostly influenced by meso and micro scale fluctuations. Many large and meso scale climate change simulations for the 21st century are based on concentration of green house gases. A better understanding of these effects on soil erosion is necessary to determine social, economic and other impacts of erosion. The second part of this study covers the time series analysis of precipitation, rainfall erosivity and wind erosion at the Marmara Region. Rainfall and runoff erosivity factors are defined by considering the results of field measurements at 10 stations. Climatological changing effects on rainfall erosion have been determined by monitoring meteorological variables. In the previous studies, Fournier Index is defined to estimate the rainfall erosivity for the study area. The Fournier Index or in other words a climatic index

Wind-Driven Erosion and Exposure Potential at Mars 2020 Rover Candidate-Landing Sites

Science.gov (United States)

Chojnacki, Matthew; Banks, Maria; Urso, Anna

2018-01-01

Aeolian processes have likely been the predominant geomorphic agent for most of Mars’ history and have the potential to produce relatively young exposure ages for geologic units. Thus, identifying local evidence for aeolian erosion is highly relevant to the selection of landing sites for future missions, such as the Mars 2020 Rover mission that aims to explore astrobiologically relevant ancient environments. Here we investigate wind-driven activity at eight Mars 2020 candidate-landing sites to constrain erosion potential at these locations. To demonstrate our methods, we found that contemporary dune-derived abrasion rates were in agreement with rover-derived exhumation rates at Gale crater and could be employed elsewhere. The Holden crater candidate site was interpreted to have low contemporary erosion rates, based on the presence of a thick sand coverage of static ripples. Active ripples at the Eberswalde and southwest Melas sites may account for local erosion and the dearth of small craters. Moderate-flux regional dunes near Mawrth Vallis were deemed unrepresentative of the candidate site, which is interpreted to currently be experiencing low levels of erosion. The Nili Fossae site displayed the most unambiguous evidence for local sand transport and erosion, likely yielding relatively young exposure ages. The downselected Jezero crater and northeast Syrtis sites had high-flux neighboring dunes and exhibited substantial evidence for sediment pathways across their ellipses. Both sites had relatively high estimated abrasion rates, which would yield young exposure ages. The downselected Columbia Hills site lacked evidence for sand movement, and contemporary local erosion rates are estimated to be relatively low. PMID:29568719

Wind-Driven Erosion and Exposure Potential at Mars 2020 Rover Candidate-Landing Sites

Science.gov (United States)

Chojnacki, Matthew; Banks, Maria; Urso, Anna

2018-02-01

Aeolian processes have likely been the predominant geomorphic agent for most of Mars' history and have the potential to produce relatively young exposure ages for geologic units. Thus, identifying local evidence for aeolian erosion is highly relevant to the selection of landing sites for future missions, such as the Mars 2020 Rover mission that aims to explore astrobiologically relevant ancient environments. Here we investigate wind-driven activity at eight Mars 2020 candidate-landing sites to constrain erosion potential at these locations. To demonstrate our methods, we found that contemporary dune-derived abrasion rates were in agreement with rover-derived exhumation rates at Gale crater and could be employed elsewhere. The Holden crater candidate site was interpreted to have low contemporary erosion rates, based on the presence of a thick sand coverage of static ripples. Active ripples at the Eberswalde and southwest Melas sites may account for local erosion and the dearth of small craters. Moderate-flux regional dunes near Mawrth Vallis were deemed unrepresentative of the candidate site, which is interpreted to currently be experiencing low levels of erosion. The Nili Fossae site displayed the most unambiguous evidence for local sand transport and erosion, likely yielding relatively young exposure ages. The downselected Jezero crater and northeast Syrtis sites had high-flux neighboring dunes and exhibited substantial evidence for sediment pathways across their ellipses. Both sites had relatively high estimated abrasion rates, which would yield young exposure ages. The downselected Columbia Hills site lacked evidence for sand movement, and contemporary local erosion rates are estimated to be relatively low.

Soil Erosion. LC Science Tracer Bullet.

Science.gov (United States)

Buydos, John F., Comp.

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

Wind erosion risk in the southwest of Buenos Aires Province, Argentina, and its relationship to the productivity index

Science.gov (United States)

Silenzi, Juan C.; Echeverría, Nora E.; Vallejos, Adrián G.; Bouza, Mariana E.; De Lucia, Martín P.

2012-01-01

Wind erosion risk (WER) for soils of each municipality in the southwest (SW) of Buenos Aires Province (10,491,172 ha) was determined using the wind erosion equation (WEQ) model. WER results from multiplying the soil erodibility index (" I") of the soil by the climatic factor ( C). WER (Mg ha -1 year -1) of each municipality was: Bahía Blanca: 22.4, Coronel Dorrego: 18.6, Coronel Pringles: 4.5, Coronel Rosales: 48.2, Coronel Suárez: 4.5, Guaminí: 3.0, Patagones: 104.6, Puan: 12.2, Saavedra: 3.0, Tornquist: 6.8, and Villarino: 31.7. The maximum weighted average of " I" (Mg ha -1 year -1) corresponded to Coronel Rosales (87.6), Patagones (87.2), Villarino (85.7), Puan (67.9); Guaminí (59.6), Coronel Dorrego (53.1), and Bahía Blanca (39.3); the remaining municipalities ranged between 34.9 and 32.1 Mg ha -1 year -1. The highest C (%) corresponded to Patagones (120), Bahía Blanca (57), Coronel Rosales (55), Villarino (37), Coronel Dorrego (35), Tornquist (21), and Puan (18); for the remaining municipalities it was 14%. The productivity index (PI) is known to establish a numerical value of the productive capacity of lands. The relationship between WER and PI, weighted averages, in all the studied municipalities was fitted by means of a linear model, WER (Mg ha -1 year -1) = 95.23 - 2.09 * PI (%) ( R2 = 66%), and a second-order polynomial model, WER (Mg ha -1 year -1) = 139.41 - 5.86 * PI (%) + 0.07 * PI 2 (%) ( R2 = 74%). No statistically significant relationship was found between WER and PI for each municipality.

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

DEFF Research Database (Denmark)

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

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

Erosion control technology: a user's guide to the use of the Universal Soil Loss Equation at waste burial facilities

International Nuclear Information System (INIS)

Nyhan, J.W.; Lane, L.J.

1986-05-01

The Universal Soil Loss Equation (USLE) enables the operators of shallow land burial sites to predict the average rate of soil erosion for each feasible alternative combination of plant cover and land management practices in association with a specified soil type, rainfall pattern, and topography. The equation groups the numerous parameters that influence erosion rate under six major factors, whose site-specific values can be expressed numerically. Over a half century of erosion research in the agricultural community has supplied information from which approximate USLE factor values can be obtained for shallow land burial sites throughout the United States. Tables and charts presented in this report make this information readily available for field use. Extensions and limitations of the USLE to shallow land burial systems in the West are discussed, followed by a detailed description of the erosion plot research performed by the nuclear waste management community at Los Alamos, New Mexico. Example applications of the USLE at shallow land burial sites are described, and recommendations for applications of these erosion control technologies are discussed

Wind Wave Behavior in Fetch and Depth Limited Estuaries

Science.gov (United States)

Karimpour, Arash; Chen, Qin; Twilley, Robert R.

2017-01-01

Wetland dominated estuaries serve as one of the most productive natural ecosystems through their ecological, economic and cultural services, such as nursery grounds for fisheries, nutrient sequestration, and ecotourism. The ongoing deterioration of wetland ecosystems in many shallow estuaries raises concerns about the contributing erosive processes and their roles in restraining coastal restoration efforts. Given the combination of wetlands and shallow bays as landscape components that determine the function of estuaries, successful restoration strategies require knowledge of wind wave behavior in fetch and depth limited water as a critical design feature. We experimentally evaluate physics of wind wave growth in fetch and depth limited estuaries. We demonstrate that wave growth rate in shallow estuaries is a function of wind fetch to water depth ratio, which helps to develop a new set of parametric wave growth equations. We find that the final stage of wave growth in shallow estuaries can be presented by a product of water depth and wave number, whereby their product approaches 1.363 as either depth or wave energy increases. Suggested wave growth equations and their asymptotic constraints establish the magnitude of wave forces acting on wetland erosion that must be included in ecosystem restoration design.

Modeling blowing snow accumulation downwind of an obstruction: The Ohara Eulerian particle distribution equation

Science.gov (United States)

Kinar, N. J.

2017-05-01

An equation was proposed to model the height of blowing snow accumulation downwind of an obstacle such as vegetation, a snow fence, a building, or a topographic feature. The equation does not require aerodynamic flow condition parameters such as wind speed, allowing for the spatial distribution of snow to be determined at locations where meteorological data is not available. However, snow particle diffusion, drift, and erosion coefficients must be estimated for application of the equation. These coefficients can be used to provide insight into the relative magnitude of blowing snow processes at a field location. Further research is required to determine efficient methods for coefficient estimation. The equation could be used with other models of wind-transported snow to predict snow accumulation downwind of an obstacle without the need for wind speed adjustments or correction equations. Applications for this equation include the design of snow fences, and the use of this equation with other hydrological models to predict snow distribution, climate change, drought, flooding, and avalanches.

Drawing a representative sample from the NCSS soil database: Building blocks for the national wind erosion network

Science.gov (United States)

Developing national wind erosion models for the continental United States requires a comprehensive spatial representation of continuous soil particle size distributions (PSD) for model input. While the current coverage of soil survey is nearly complete, the most detailed particle size classes have c...

An Assessment of the Impact of Urbanization on Soil Erosion in Inner Mongolia

Directory of Open Access Journals (Sweden)

Li-Yan Wang

2018-03-01

Full Text Available Inner Mongolia, an autonomous region of the People’s Republic of China, has experienced severe soil erosion following a period of rapid economic development and urbanization. To investigate how urbanization has influenced the extent of soil erosion in Inner Mongolia, we used urbanization and soil erosion data from 2000 through 2010 to determine the relationship between urbanization and soil erosion patterns. Two empirical equations—the Revised Universal Soil Loss Equation (RUSLE and the Revised Wind Erosion Equation (RWEQ—were used to estimate the intensity of soil erosion, and we performed backward linear regression to model how it changed with greater urbanization. There was an apparent increase in the rate of urbanization and a decrease in the area affected by soil erosion in 2010 compared to the corresponding values for 2000. The urban population stood at 11.32 million in 2010, which represented a 16.47% increase over that in 2000. The area affected by soil erosion in 2000 totaled 704,817 km2, yet it had decreased to 674,135 km2 by 2010. However, a path of modest urban development (rural–urban mitigation and reasonable industrial structuring (the development of GDP-2 may partially reduce urbanization’s ecological pressure and thus indirectly reduce the threat of soil erosion to human security. Therefore, to better control soil erosion in Inner Mongolia during the process of urbanization, the current model of economic development should be modified to improve the eco-efficiency of urbanization, while also promoting new modes of urbanization that are environmentally sustainable, cost-effective, and conserve limited resources.

A simple method to downscale daily wind statistics to hourly wind data

OpenAIRE

Guo, Zhongling

2013-01-01

Wind is the principal driver in the wind erosion models. The hourly wind speed data were generally required for precisely wind erosion modeling. In this study, a simple method to generate hourly wind speed data from daily wind statistics (daily average and maximum wind speeds together or daily average wind speed only) was established. A typical windy location with 3285 days (9 years) measured hourly wind speed data were used to validate the downscaling method. The results showed that the over...

Assessing the vegetation canopy influences on wind flow using wind ...

Indian Academy of Sciences (India)

Artificial plastic vegetations with different porosity and canopy shape were introduced as ... Wind erosion is the Aeolian process by which soil particles are detached from ..... the stabilizing role of vegetation on wind erosion. And therefore, for ...

75 FR 75961 - Notice of Implementation of the Wind Erosion Prediction System for Soil Erodibility System...

Science.gov (United States)

2010-12-07

... implementation of the WEPS system does not affect the Highly Erodible Map Unit List contained in the NRCS Field Office Technical Guide as of January 1, 1990. This 1990 list will continue to be used for all erodibility... plant damage, and predict PM-10 emissions when wind speeds exceed the erosion threshold. The WEPS model...

Changes in wind erosion over a 25-year restoration chronosequence on the south edge of the Tengger Desert, China: implications for preventing desertification.

Science.gov (United States)

Ma, Quanlin; Fehmi, Jeffrey S; Zhang, Dekui; Fan, Baoli; Chen, Fang

2017-08-23

Wind erosion is a primary cause of desertification as well as being a serious ecological problem in arid and semi-arid areas across the world. To determine mechanisms for restoring desertified lands, an unrestored shifting sand dune and three formerly shifting sand dunes (desertified lands) that had been enclosed and afforested for 5, 15, and 25 years were selected for evaluation on the south edge of the Tengger Desert, China. Based on sampling heights between 0.2 and 3 m, the critical threshold average wind speed was 6.5 m s -1 at 2 m where the sand transport rate was reduced from 285.9 kg m -2  h -1 on the unrestored dunes to 9.1 and 1.8 kg m -2  h -1 on the sites afforested and enclosed for 5 and 15 years, respectively. The percentage of wind eroded area was reduced from 99.9% on the unrestored dune to 94.5, 9.0, and 0.5% on the sites afforested and enclosed for 5, 15, and 25 years, respectively. Wind erosion was effectively reduced after 15 years. Although there were different driving factors for wind erosion mitigation on the different restoration stages, an increase in the vegetation cover, surface roughness, soil shear strength, soil clay content, organic matter, and reduction in the near-surface wind speed were the primary variables associated with the restoration chronosequence. We conclude that reducing the wind speed and developing a biological crust through vegetation restoration were the critical components for restoration of desertified land.

Contributions of solar-wind induced potential sputtering to the lunar surface erosion rate and it's exosphere

Science.gov (United States)

Alnussirat, S. T.; Barghouty, A. F.; Edmunson, J. E.; Sabra, M. S.; Rickman, D. L.

2018-04-01

Sputtering of lunar regolith by solar-wind protons and heavy ions with kinetic energies of about 1 keV/amu is an important erosive process that affects the lunar surface and exosphere. It plays an important role in changing the chemical composition and thickness of the surface layer, and in introducing material into the exosphere. Kinetic sputtering is well modeled and understood, but understanding of mechanisms of potential sputtering has lagged behind. In this study we differentiate the contributions of potential sputtering from the standard (kinetic) sputtering in changing the chemical composition and erosion rate of the lunar surface. Also we study the contribution of potential sputtering in developing the lunar exosphere. Our results show that potential sputtering enhances the total characteristic sputtering erosion rate by about 44%, and reduces sputtering time scales by the same amount. Potential sputtering also introduces more material into the lunar exosphere.

Predicción de la erosión eólica potencial con el modelo EWEQ en dos suelos loesicos: efectos de las condiciones climáticas Wind erosion prediction with the EWEQ model in two loess soils: effects of climatic condition

Directory of Open Access Journals (Sweden)

Silvia Beatriz Aimar

2011-12-01

. The objective of this study was to compare the predicted EEP of two soils by means of the Spanish Version of the Wind Erosion Equation (EWEQ, with field-measured EEP in a semiarid environment of Argentina, loaded with different climatic C factors. Wind erosion measurements were carried out along one year in a Typic Ustipsammment and an Entic Haplustoll, both maintained bare and flat along the sampling period. Results indicated that EEP was higher in the Ustipsamment (270 Mg ha-1 yr-1 than in the Haplustoll (40 Mg ha-1 yr-1. These amounts represented 21,3 and 3,1 mm losses of the topsoil. Wind erosion of the Ustipsamment was twice in Spring-Summer than in Autumn-Winter. This effect was not observed in the Haplustoll, due to a slower drying rate after a rainfall event, which maintained the soil surface moist during a longer period of time. Storm duration explained 40% of the wind erosion variability in both soils. Wind erosion rates (Qt, EEP per unit time correlated positively with the mean wind speed in both soils. At similar wind speeds, Qt was always higher in the Typic Ustipsamment. The EEP calculated with a C factor corresponding to the sampling period (30,3 was the most similar to field measurements, but EWEQ underestimated wind erosion by 43% for the Haplustoll and by 18% for the Ustipsamment. The EWEQ model should include different climatic C factors in order to offer the user the prediction of wind erosion under variable climatic scenarios.

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

Science.gov (United States)

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

Experimental study on influence of vegetation coverage on runoff in wind-water erosion crisscross region

Science.gov (United States)

Wang, Jinhua; Zhang, Ronggang; Sun, Juan

2018-02-01

Using artificial rainfall simulation method, 23 simulation experiments were carried out in water-wind erosion crisscross region in order to analyze the influence of vegetation coverage on runoff and sediment yield. The experimental plots are standard plots with a length of 20m, width of 5m and slope of 15 degrees. The simulation experiments were conducted in different vegetation coverage experimental plots based on three different rainfall intensities. According to the experimental observation data, the influence of vegetation coverage on runoff and infiltration was analyzed. Vegetation coverage has a significant impact on runoff, and the higher the vegetation coverage is, the smaller the runoff is. Under the condition of 0.6mm/min rainfall intensity, the runoff volume from the experimental plot with 18% vegetation coverage was 1.2 times of the runoff from the experimental with 30% vegetation coverage. What’s more, the difference of runoff is more obvious in higher rainfall intensity. If the rainfall intensity reaches 1.32mm/min, the runoff from the experimental plot with 11% vegetation coverage is about 2 times as large as the runoff from the experimental plot with 53%vegetation coverage. Under the condition of small rainfall intensity, the starting time of runoff in the experimental plot with higher vegetation coverage is later than that in the experimental plot with low vegetation coverage. However, under the condition of heavy rainfall intensity, there is no obvious difference in the beginning time of runoff. In addition, the higher the vegetation coverage is, the deeper the rainfall infiltration depth is.The results can provide reference for ecological construction carried out in wind erosion crisscross region with serious soil erosion.

Parametrization of the increase of the aeolian erosion threshold wind friction velocity due to soil moisture for arid and semi-arid areas

Directory of Open Access Journals (Sweden)

F. Fécan

1999-01-01

Full Text Available Large-scale simulation of the soil-derived dust emission in semi-arid regions needs to account for the influence of the soil moisture on the wind erosion threshold. Soil water retention consists of molecular adsorption on the soil grain surface and capillary forces between the grain. Interparticle capillary forces (characterized by the moisture tension are the main factor responsible for the increase of the wind erosion threshold observed when the soil moisture increases. When the soil moisture content is close to but smaller than the maximum amount of adsorbed water, w' (depending on the soil texture, these capillary forces are considered as not strong enough to significantly increase the erosion threshold. An expression of the moisture tension as a function of soil moisture and w' is derived from retention curves. From this expression, a parametrization of the ratio of the wet to dry erosion thresholds has been developed as a function of soil moisture and soil texture. The coefficients of this parametrization have been determined by using experimental data from the literature. An empirical relationship between w' and soil clay content has been established. The erosion threshold ratios simulated for different soil textures were found to be in good agreement with the experimental data.Key words. Atmospheric composition and structure (Aerosols and particles · Hydrology (soil moisture

Probabilistic Forecasts of Wind Power Generation by Stochastic Differential Equation Models

DEFF Research Database (Denmark)

Møller, Jan Kloppenborg; Zugno, Marco; Madsen, Henrik

2016-01-01

The increasing penetration of wind power has resulted in larger shares of volatile sources of supply in power systems worldwide. In order to operate such systems efficiently, methods for reliable probabilistic forecasts of future wind power production are essential. It is well known...... that the conditional density of wind power production is highly dependent on the level of predicted wind power and prediction horizon. This paper describes a new approach for wind power forecasting based on logistic-type stochastic differential equations (SDEs). The SDE formulation allows us to calculate both state......-dependent conditional uncertainties as well as correlation structures. Model estimation is performed by maximizing the likelihood of a multidimensional random vector while accounting for the correlation structure defined by the SDE formulation. We use non-parametric modelling to explore conditional correlation...

Bioengineering Technology to Control River Soil Erosion using Vetiver (Vetiveria Zizaniodes)

Science.gov (United States)

Sriwati, M.; Pallu, S.; Selintung, M.; Lopa, R.

2018-04-01

Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock or dissolved material from one location on the earth’s crust, and then transport it away to another location. Bioengineering is an attempt to maximise the use of vegetation components along riverbanks to cope with landslides and erosion of river cliffs and another riverbank damage. This study aims to analyze the bioengineering of Vetiver as a surface layer for soil erosion control using slope of 100, 200, and 300. This study is conducted with 3 variations of rain intensity (I), at 103 mm/hour, 107 mm/hour, and 130 mm/hour by using rainfall simulator tool. In addition, the USLE (Universal Soil Loss Equation) method is used in order to measure the rate of soil erosion. In this study, there are few USLE model parameters were used such as rainfall erosivity factor, soil erodibility factor, length-loss slope and stepness factor, cover management factor, and support practise factor. The results demonstrated that average of reduction of erosion rate using Vetiver, under 3 various rainfalls, namely rainfall intensity 103 mm/hr had reduced 84.971%, rainfall intensity 107 mm/hr had reduced 86.583 %, rainfall intensity 130 mm/hr had reduced 65.851%.

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

Directory of Open Access Journals (Sweden)

Kissi B.

2012-07-01

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

PDF models and synthetic model for the wind speed fluctuations based on the resolution of Langevin equation

International Nuclear Information System (INIS)

Calif, Rudy

2012-01-01

Highlights: ► Probability Density Functions are proposed to fit the wind speed fluctuations distributions for three representative classes. ► Stochastic simulations are performed using a Langevin equation for each class. ► The properties of simulated and measured wind speed sequences are close. -- Abstract: Wind energy production is very sensitive to turbulent wind speed. Thus rapid variation of wind speed due to changes in the local meteorological conditions can lead to electrical power variations of the order of the nominal power output, in particular when wind power variations on very short time scales, range at few seconds to 1 h, are considered. In small grid as they exist on islands (Guadeloupean Archipelago: French West Indies) such fluctuations can cause instabilities in case of intermediate power shortages. The developed analysis in reveals three main classes of time series for the wind speed fluctuations. In this work, Probability Density Functions (PDFs) are proposed to fit the wind speed fluctuations distributions in each class. After, to simulate wind speed fluctuations sequences, we use a stochastic differential equation, the Langevin equation considering Gaussian turbulence PDF (class I), Gram–Charlier PDF (class II) and a mixture of gaussian PDF (class III). The statistical and dynamical properties of simulated wind sequences are close to those of measured wind sequences, for each class.

Definition of tolerable soil erosion values

Directory of Open Access Journals (Sweden)

G. Sparovek

1997-09-01

Full Text Available Although the criteria for defining erosion tolerance are well established, the limits generally used are not consistent with natural, economical and technological conditions. Rates greater than soil formation can be accepted only until a minimum of soil depth is reached, provided that they are not associated with environmental hazard or productivity losses. A sequence of equations is presented to calculate erosion tolerance rates through time. The selection of equation parameters permits the definition of erosion tolerance rates in agreement with environmental, social and technical needs. The soil depth change that is related to irreversible soil degradation can be calculated. The definition of soil erosion tolerance according to these equations can be used as a guideline for sustainable land use planning and is compatible with expert systems.

The Major Cause of Observed Erosion Surge on the Beaches North ...

African Journals Online (AJOL)

Surges in coastal erosion north of Dar es Salaam city have been documented from 1977 to the early 1980s and around 1997/98. Analysis of the wind data shows that the documented increase in coastal erosion coincided with increased wind speeds. Extreme winds in excess of 10-11 m s-1 were experienced during ...

Probabilistic Forecast of Wind Power Generation by Stochastic Differential Equation Models

KAUST Repository

Elkantassi, Soumaya

2017-04-01

Reliable forecasting of wind power generation is crucial to optimal control of costs in generation of electricity with respect to the electricity demand. Here, we propose and analyze stochastic wind power forecast models described by parametrized stochastic differential equations, which introduce appropriate fluctuations in numerical forecast outputs. We use an approximate maximum likelihood method to infer the model parameters taking into account the time correlated sets of data. Furthermore, we study the validity and sensitivity of the parameters for each model. We applied our models to Uruguayan wind power production as determined by historical data and corresponding numerical forecasts for the period of March 1 to May 31, 2016.

Effects of Long-term Conservation Tillage on Soil Nutrients in Sloping Fields in Regions Characterized by Water and Wind Erosion

Science.gov (United States)

Tan, Chunjian; Cao, Xue; Yuan, Shuai; Wang, Weiyu; Feng, Yongzhong; Qiao, Bo

2015-12-01

Conservation tillage is commonly used in regions affected by water and wind erosion. To understand the effects of conservation tillage on soil nutrients and yield, a long-term experiment was set up in a region affected by water and wind erosion on the Loess Plateau. The treatments used were traditional tillage (CK), no tillage (NT), straw mulching (SM), plastic-film mulching (PM), ridging and plastic-film mulching (RPM) and intercropping (In). Our results demonstrate that the available nutrients in soils subjected to non-traditional tillage treatments decreased during the first several years and then remained stable over the last several years of the experiment. The soil organic matter and total nitrogen content increased gradually over 6 years in all treatments except CK. The nutrient content of soils subjected to conservative tillage methods, such as NT and SM, were significantly higher than those in soils under the CK treatment. Straw mulching and film mulching effectively reduced an observed decrease in soybean yield. Over the final 6 years of the experiment, soybean yields followed the trend RPM > PM > SM > NT > CK > In. This trend has implications for controlling soil erosion and preventing non-point source pollution in sloping fields by sacrificing some food production.

A fast, parallel algorithm to solve the basic fluvial erosion/transport equations

Science.gov (United States)

Braun, J.

2012-04-01

Quantitative models of landform evolution are commonly based on the solution of a set of equations representing the processes of fluvial erosion, transport and deposition, which leads to predict the geometry of a river channel network and its evolution through time. The river network is often regarded as the backbone of any surface processes model (SPM) that might include other physical processes acting at a range of spatial and temporal scales along hill slopes. The basic laws of fluvial erosion requires the computation of local (slope) and non-local (drainage area) quantities at every point of a given landscape, a computationally expensive operation which limits the resolution of most SPMs. I present here an algorithm to compute the various components required in the parameterization of fluvial erosion (and transport) and thus solve the basic fluvial geomorphic equation, that is very efficient because it is O(n) (the number of required arithmetic operations is linearly proportional to the number of nodes defining the landscape), and is fully parallelizable (the computation cost decreases in a direct inverse proportion to the number of processors used to solve the problem). The algorithm is ideally suited for use on latest multi-core processors. Using this new technique, geomorphic problems can be solved at an unprecedented resolution (typically of the order of 10,000 X 10,000 nodes) while keeping the computational cost reasonable (order 1 sec per time step). Furthermore, I will show that the algorithm is applicable to any regular or irregular representation of the landform, and is such that the temporal evolution of the landform can be discretized by a fully implicit time-marching algorithm, making it unconditionally stable. I will demonstrate that such an efficient algorithm is ideally suited to produce a fully predictive SPM that links observationally based parameterizations of small-scale processes to the evolution of large-scale features of the landscapes on

Wear Resistance Performance of Conventional and Non-Conventional Wind Turbine Blades with TiN Nano-Coating

Directory of Open Access Journals (Sweden)

Muhammad Hasibul Hasan

2017-09-01

Full Text Available Efficiency and durability are critical issues that affect widely-adopted aerofoil-power generator as a sustainable source of electrical power. Even though high wind power density can be achieved; installing wind turbines in desert condition has difficulties including thermal variation, high turbulence and sand storms. Sand blasting on turbine blade surface at high velocities causes erosion resulting turbine efficiency drop. Damage-induced erosion phenomena and aeroelastic performance of the blades needed to be investigated. Suitable coating may prevent erosion to a great extent. A numerical investigation of erosion on NACA 4412 wind turbine blade has been performed using commercial computational fluid dynamics software ANSYS FLUENT 14.5 release. Discrete phase model (DPM has been used for modelling multi-phase flow of air and sand particles over the turbine blade. Governing equations have been solved by finite volume method (FVM. Conventional 30-70% glass fibre resin and non-conventional jute fibre composite have been used as turbine blade material. Sand particles of  diameter have been injected from 20, 30, 45, 60 and 90 degree angles at 500C temperature. Erosion rate, wall shear stress and strain rate have been calculated for different wind velocities and impingement angles. Simulation results for higher velocities deviate from the results observed at lower wind velocities. In simulation, erosion rate is highest for impingement angle at low wind velocities, which has been validated by experiment with a mean absolute error (MAE of 5.56%. Erosion rate and wall shear stress are higher on jute composite fibre than glass fibre resin. Developed shear stress on wind turbine blade surface is highest for  impingement angle at all velocities. On the other hand, exerted pressure on turbine blade surface is found highest for 9  angle of attack. Experimental results, with or without Titanium nitride(TiN nano-coating, also revealed that surface roughness

Rain erosion of wind turbine blade coatings using discrete water jets: Effects of water cushioning, substrate geometry, impact distance, and coating properties

DEFF Research Database (Denmark)

Zhang, Shizhong; Dam-Johansen, Kim; Bernad, Pablo L.

2015-01-01

Rapid and reliable rain erosion screening of blade coatings for wind turbines is a strong need in the coatings industry. One possibility in this direction is the use of discrete water jets, where so-called jet slugs are impacted on a coating surface. Previous investigations have mapped...... the influence of water jet slug velocity and impact frequency. In the present work, the effects on coating erosion of water cushioning, substrate curvature, and water nozzle-coating distance were explored. The investigations showed that in some cases water cushioning (the presence of a liquid film...... on the coating surface prior to impact) influences the erosion. Contrary to this, substrate curvature and the water nozzle-coating distance (

Local Equation of State for Protons, and Implications for Proton Heating in the Solar Wind.

Science.gov (United States)

Zaslavsky, A.; Maksimovic, M.; Kasper, J. C.

2017-12-01

The solar wind protons temperature is observed to decrease with distance to the Sun at a slower rate than expected from an adiabatic expansion law: the protons are therefore said to be heated. This observation raises the question of the evaluation of the heating rate, and the question of the heat source.These questions have been investigated by previous authors by gathering proton data on various distances to the Sun, using spacecraft as Helios or Ulysses, and then computing the radial derivative of the proton temperature in order to obtain a heating rate from the internal energy equation. The problem of such an approach is the computation of the radial derivative of the temperature profile, for which uncertainties are very large, given the dispersion of the temperatures measured at a given distance.An alternative approach, that we develop in this paper, consists in looking for an equation of state that links locally the pressure (or temperature) to the mass density. If such a relation exists then one can evaluate the proton heating rate on a local basis, without having any space derivative to compute.Here we use several years of STEREO and WIND proton data to search for polytropic equation of state. We show that such relationships are indeed a good approximation in given solar wind's velocity intervals and deduce the associated protons heating rates as a function of solar wind's speed. The obtained heating rates are shown to scale from around 1 kW/kg in the slow wind to around 10 kW/kg in the fast wind, in remarkable agreement with the rate of energy observed by previous authors to cascade in solar wind's MHD turbulence at 1 AU. These results therefore support the idea of proton turbulent heating in the solar wind.

Erosion of Earthen Levees by Wave Action

Science.gov (United States)

Ozeren, Y.; Wren, D. G.; Reba, M. L.

2016-02-01

Earthen levees of aquaculture and irrigation reservoirs in the United States often experience significant erosion due to wind-generated waves. Typically constructed using local soils, unprotected levees are subjected to rapid erosion and retreat due to wind generated waves and surface runoff. Only a limited amount of published work addresses the erosion rates for unprotected levees, and producers who rely on irrigation reservoirs need an economic basis for selecting a protection method for vulnerable levees. This, in turn, means that a relationship between wave energy and erosion of cohesive soils is needed. In this study, laboratory experiments were carried out in order to quantify wave induced levee erosion and retreat. A model erodible bank was packed using a soil consisting of approximately 14% sand, 73% silt, and 13% clay in a 20.6 m long 0.7 m wide and 1.2 m deep wave tank at the USDA-ARS, National Sedimentation Laboratory in Oxford MS. The geometry of the levee face was monitored by digital camera and the waves were measured by means of 6 capacitance wave staffs. Relationships were established between levee erosion, edge and retreat rates, and incident wave energy.

Reynolds Averaged Navier-Stokes (RANS) equation solutions of wind turbine wakes

Energy Technology Data Exchange (ETDEWEB)

Ludwig, Daniel Evandro; Horn, Diego Anderson; Petry, Adriane Prisco [Thermal and Energy Study Group, Mechanical Engeneering Department, Federal University of Rio Grande do Sul, Porto Alegre (Brazil)], E-mail: adrianep@mecanica.ufrgs.br

2010-07-01

This paper aims to evaluate the influence of three different turbulence models in the study of a wind turbine wake. Numerical Simulation is used as working tool to characterize the flow through the wind turbines, it is used the numeric simulation. The numerical analysis is based on the finite volume method and the Reynolds Averaged Navier-Stokes (RANS) equations. Three turbulence models are used to represent the total effects of turbulence in the flow: the two equations k-classical and the RNG k- models, based on the turbulent viscosity; and the Shear Stress Transport (SST) model, based on the transport of the Reynolds tensor. The results of the 'u' velocity profiles are compared to experimental data from Vermeer (2003) at distances equivalent to 2, 4, 6, 8, 10 and 16 diameters downstream from the turbine. Results shows that the SST model gives better results until 6 diameters, beyond this distance there is no significant differences between the compared models. (author)

Aeroelastic equations of motion of a Darrieus vertical-axis wind-turbine blade

Science.gov (United States)

Kaza, K. R. V.; Kvaternik, R. G.

1979-01-01

The second-degree nonlinear aeroelastic equations of motion for a slender, flexible, nonuniform, Darrieus vertical-axis wind turbine blade which is undergoing combined flatwise bending, edgewise bending, torsion, and extension are developed using Hamilton's principle. The blade aerodynamic loading is obtained from strip theory based on a quasi-steady approximation of two-dimensional incompressible unsteady airfoil theory. The derivation of the equations has its basis in the geometric nonlinear theory of elasticity and the resulting equations are consistent with the small deformation approximation in which the elongations and shears are negligible compared to unity. These equations are suitable for studying vibrations, static and dynamic aeroelastic instabilities, and dynamic response. Several possible methods of solution of the equations, which have periodic coefficients, are discussed.

How does slope form affect erosion in CATFLOW-SED?

Science.gov (United States)

Gabelmann, Petra; Wienhöfer, Jan; Zehe, Erwin

2016-04-01

Erosion is a severe environmental problem in agro-ecosystems with highly erodible loess soils. It is controlled by various factors, e.g. rainfall intensity, initial wetness conditions, soil type, land use and tillage practice. Furthermore slope form and gradient have been shown to influence erosion amounts to a large extent. Within the last fifty years, various erosion models have been developed to describe the erosion process, estimate erosion amounts and identify erosion-prone areas. These models differ in terms of complexity, the processes which are considered, and the data required for model calibration and they can be categorised into empirical or statistical, conceptual, and physically-based models. CATFLOW-SED is a process-based hydrology and erosion model that can operate on catchment and hillslope scales. Soil water dynamics are described by the Richards equation including effective approaches for preferential flow. Evapotranspiration is simulated using an approach based on the Penman-Monteith equation. The model simulates overland flow using the diffusion wave equation. Soil detachment is related to the attacking forces of rainfall and overland flow, and the erosion resistance of soil. Sediment transport capacity and sediment deposition are related to overland flow velocity using the equation of Engelund and Hansen and the sinking velocity of grain sizes respectively. We performed a study to analyse the erosion process on different virtual hillslopes, with varying slope gradient and slope form, using the CATFLOW-SED model. We explored the role of landform on erosion and sedimentation, particularly we look for forms that either maximise or minimise erosion. Results indicate the importance to performing the process implementation within physically meaningful limits and choose appropriate model parameters respectively.

Validation of Simplified Load Equations Through Loads Measurement and Modeling of a Small Horizontal-Axis Wind Turbine Tower

Energy Technology Data Exchange (ETDEWEB)

Dana, Scott [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Van Dam, Jeroen J [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Damiani, Rick R [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2018-04-24

As part of an ongoing effort to improve the modeling and prediction of small wind turbine dynamics, the National Renewable Energy Laboratory (NREL) tested a small horizontal-axis wind turbine in the field at the National Wind Technology Center. The test turbine was a 2.1-kW downwind machine mounted on an 18-m multi-section fiberglass composite tower. The tower was instrumented and monitored for approximately 6 months. The collected data were analyzed to assess the turbine and tower loads and further validate the simplified loads equations from the International Electrotechnical Commission (IEC) 61400-2 design standards. Field-measured loads were also compared to the output of an aeroelastic model of the turbine. In particular, we compared fatigue loads as measured in the field, predicted by the aeroelastic model, and calculated using the simplified design equations. Ultimate loads at the tower base were assessed using both the simplified design equations and the aeroelastic model output. The simplified design equations in IEC 61400-2 do not accurately model fatigue loads and a discussion about the simplified design equations is discussed.

Soil erosion assessment using the Universal Soil Loss Equation (USLE) in a GIS framework: A case study of Zacatecas, México

Science.gov (United States)

Betanzos Arroyo, L. I.; Prol Ledesma, R. M.; da Silva Pinto da Rocha, F. J. P.

2014-12-01

The Universal Soil Loss Equation (USLE), which is considered to be a contemporary approach in soil loss assessment, was used to assess soil erosion hazard in the Zacatecas mining district. The purpose of this study is to produce erosion susceptibility maps for an area that is polluted with mining tailings which are susceptible to erosion and can disperse the particles that contain heavy metals and other toxic elements. USLE method is based in the estimation of soil loss per unit area and takes into account specific parameters such as precipitation data, topography, soil erodibility, erosivity and runoff. The R-factor (rainfall erosivity) was calculated from monthly and annual precipitation data. The K-factor (soil erodibility) was estimated using soil maps available from the CONABIO at a scale of 1:250000. The LS-factor (slope length and steepness) was determined from a 30-m digital elevation model. A raster-based Geographic Information System (GIS) was used to interactively calculate soil loss and map erosion hazard. The results show that estimated erosion rates ranged from 0 to 4770.48 t/ha year. Maximum proportion of the total area of the Zacatecas mining district have nil to very extremely slight erosion severity. Small areas in the central and south part of the study area shows the critical condition requiring sustainable land management.

Spectrum Analysis of Inertial and Subinertial Motions Based on Analyzed Winds and Wind-Driven Currents from a Primitive Equation General Ocean Circulation Model.

Science.gov (United States)

1982-12-01

1Muter.Te Motions Based on Ana lyzed Winds and wind-driven December 1982 Currents from. a Primitive Squat ion General a.OW -love"*..* Oean Circulation...mew se"$ (comeS.... do oISN..u am ae~ 00do OWaor NUN Fourier and Rotary Spc , Analysis Modeled Inertial and Subinrtial Motion 4 Primitive Equation

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.

Calibration and verification of numerical runoff and erosion model

Directory of Open Access Journals (Sweden)

Gabrić Ognjen

2015-01-01

Full Text Available Based on the field and laboratory measurements, and analogous with development of computational techniques, runoff and erosion models based on equations which describe the physics of the process are also developed. Based on the KINEROS2 model, this paper presents basic modelling principles of runoff and erosion processes based on the St. Venant's equations. Alternative equations for friction calculation, calculation of source and deposition elements and transport capacity are also shown. Numerical models based on original and alternative equations are calibrated and verified on laboratory scale model. According to the results, friction calculation based on the analytic solution of laminar flow must be included in all runoff and erosion models.

Three procedures for estimating erosion from construction areas

International Nuclear Information System (INIS)

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

1978-01-01

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

A comparison of methods in estimating soil water erosion

Directory of Open Access Journals (Sweden)

Marisela Pando Moreno

2012-02-01

Full Text Available A comparison between direct field measurements and predictions of soil water erosion using two variant; (FAO and R/2 index of the Revised Universal Soil Loss Equation (RUSLE was carried out in a microcatchment o 22.32 km2 in Northeastern Mexico. Direct field measurements were based on a geomorphologic classification of the area; while environmental units were defined for applying the equation. Environmental units were later grouped withir geomorphologic units to compare results. For the basin as a whole, erosion rates from FAO index were statistical!; equal to those measured on the field, while values obtained from the R/2 index were statistically different from the res and overestimated erosion. However, when comparing among geomorphologic units, erosion appeared overestimate! in steep units and underestimated in more flat areas. The most remarkable differences on erosion rates, between th( direct and FAO methods, were for those units where gullies have developed, fn these cases, erosion was underestimated by FAO index. Hence, it is suggested that a weighted factor for presence of gullies should be developed and included in RUSLE equation.

Interactions Between Wind Erosion, Vegetation Structure, and Soil Stability in Groundwater Dependent Plant Communities

Science.gov (United States)

Vest, K. R.; Elmore, A. J.; Okin, G. S.

2009-12-01

Desertification is a human induced global phenomenon causing a loss of biodiversity and ecosystem productivity. Semi-arid grasslands are vulnerable to anthropogenic impacts (i.e., groundwater pumping and surface water diversion) that decrease vegetation cover and increase bare soil area leading to a greater probability of soil erosion, potentially enhancing feedback processes associated with desertification. To enhance our understanding of interactions between anthropogenic, physical, and biological factors causing desertification, this study used a combination of modeling and field observations to examine the relationship between chronic groundwater pumping and vegetation cover change and its effects on soil erosion and stability. The work was conducted in Owens Valley California, where a long history of groundwater pumping and surface water diversion has lead to documented vegetation changes. The work examined hydrological, ecological and biogeochemical factors across thirteen sites in Owens Valley. We analyzed soil stability, vegetation and gap size, soil organic carbon, and we also installed Big Spring Number Eight (BSNE) catchers to calculate mass transport of aeolian sediment across sites. Mass transport calculations were used to validate a new wind erosion model that represents the effect of porous vegetation on surface windshear velocity. Results across two field seasons show that the model can be used to predict mass transport, and areas with increased groundwater pumping show a greater susceptibility to erosion. Sediment collected in BSNE catchers was positively correlated with site gap size. Additionally, areas with larger gap sizes have a greater threshold shear velocity and soil stability, yet mass transport was greater at these sites than at sites with smaller gap sizes. Although modeling is complicated by spatial variation in multiple model parameters (e.g., gap size, threshold shear velocity in gaps), our results support the hypothesis that soils

On the Material Characterisation of Wind Turbine Blade Coatings: The Effect of Interphase Coating–Laminate Adhesion on Rain Erosion Performance

Directory of Open Access Journals (Sweden)

Enrique Cortés

2017-09-01

Full Text Available Rain erosion damage, caused by repeated droplet impact on wind turbine blades, is a major cause for concern, even more so at offshore locations with larger blades and higher tip speeds. Due to the negative economic influence of blade erosion, all wind turbine Original Equipment Manufacturers (OEMs are actively seeking solutions. In most cases, since the surface coating plays a decisive role in the blade manufacture and overall performance, it has been identified as an area where a solution may be obtained. In this research, two main coating technologies have been considered: In-mould coatings (Gel coating applied during moulding on the entire blade surface and the post-mould coatings specifically developed for Leading Edge Protection (LEP. The coating adhesion and erosion is affected by the shock waves created by the collapsing water droplets on impact. The stress waves are reflected and transmitted to the laminate substrate, so microstructural discontinuities in coating layers and interfaces play a key role on its degradation and may accelerate erosion by delamination. Analytical and numerical models are commonly used to relate lifetime prediction and to identify suitable coating and composite substrate combinations based on their potential stress reduction on the interface. Nevertheless, in order to use them, it is necessary to measure the contact adhesion resistance of the multi-layered system interfaces. The rain erosion performance is assessed using an accelerated testing technique, whereby the test material is repeatedly impacted at high speed with water droplets in a Whirling Arm Rain Erosion Rig (WARER. The materials, specifically the coating–laminate interphase region and acoustic properties, are further characterised by several laboratory tests, including Differential Scanning Calorimetry (DSC, pull-off testing, peeling–adhesion testing and nanoindentation testing. This body of work includes a number of case studies. The first case

On the Material Characterisation of Wind Turbine Blade Coatings: The Effect of Interphase Coating–Laminate Adhesion on Rain Erosion Performance

Science.gov (United States)

Cortés, Enrique; Sánchez, Fernando; Madramany, Borja

2017-01-01

Rain erosion damage, caused by repeated droplet impact on wind turbine blades, is a major cause for concern, even more so at offshore locations with larger blades and higher tip speeds. Due to the negative economic influence of blade erosion, all wind turbine Original Equipment Manufacturers (OEMs) are actively seeking solutions. In most cases, since the surface coating plays a decisive role in the blade manufacture and overall performance, it has been identified as an area where a solution may be obtained. In this research, two main coating technologies have been considered: In-mould coatings (Gel coating) applied during moulding on the entire blade surface and the post-mould coatings specifically developed for Leading Edge Protection (LEP). The coating adhesion and erosion is affected by the shock waves created by the collapsing water droplets on impact. The stress waves are reflected and transmitted to the laminate substrate, so microstructural discontinuities in coating layers and interfaces play a key role on its degradation and may accelerate erosion by delamination. Analytical and numerical models are commonly used to relate lifetime prediction and to identify suitable coating and composite substrate combinations based on their potential stress reduction on the interface. Nevertheless, in order to use them, it is necessary to measure the contact adhesion resistance of the multi-layered system interfaces. The rain erosion performance is assessed using an accelerated testing technique, whereby the test material is repeatedly impacted at high speed with water droplets in a Whirling Arm Rain Erosion Rig (WARER). The materials, specifically the coating–laminate interphase region and acoustic properties, are further characterised by several laboratory tests, including Differential Scanning Calorimetry (DSC), pull-off testing, peeling–adhesion testing and nanoindentation testing. This body of work includes a number of case studies. The first case study compares

On the Material Characterisation of Wind Turbine Blade Coatings: The Effect of Interphase Coating-Laminate Adhesion on Rain Erosion Performance.

Science.gov (United States)

Cortés, Enrique; Sánchez, Fernando; O'Carroll, Anthony; Madramany, Borja; Hardiman, Mark; Young, Trevor M

2017-09-28

Rain erosion damage, caused by repeated droplet impact on wind turbine blades, is a major cause for concern, even more so at offshore locations with larger blades and higher tip speeds. Due to the negative economic influence of blade erosion, all wind turbine Original Equipment Manufacturers (OEMs) are actively seeking solutions. In most cases, since the surface coating plays a decisive role in the blade manufacture and overall performance, it has been identified as an area where a solution may be obtained. In this research, two main coating technologies have been considered: In-mould coatings (Gel coating) applied during moulding on the entire blade surface and the post-mould coatings specifically developed for Leading Edge Protection (LEP). The coating adhesion and erosion is affected by the shock waves created by the collapsing water droplets on impact. The stress waves are reflected and transmitted to the laminate substrate, so microstructural discontinuities in coating layers and interfaces play a key role on its degradation and may accelerate erosion by delamination. Analytical and numerical models are commonly used to relate lifetime prediction and to identify suitable coating and composite substrate combinations based on their potential stress reduction on the interface. Nevertheless, in order to use them, it is necessary to measure the contact adhesion resistance of the multi-layered system interfaces. The rain erosion performance is assessed using an accelerated testing technique, whereby the test material is repeatedly impacted at high speed with water droplets in a Whirling Arm Rain Erosion Rig (WARER). The materials, specifically the coating-laminate interphase region and acoustic properties, are further characterised by several laboratory tests, including Differential Scanning Calorimetry (DSC), pull-off testing, peeling-adhesion testing and nanoindentation testing. This body of work includes a number of case studies. The first case study compares two

[Biological soil crust nitrogenase activity and its responses to hydro-thermic factors in different erosion regions on the Loess Plateau, China].

Science.gov (United States)

Ming, Jiao; Zhao, Yun-Ge; Xu, Ming-Xiang; Yang, Li-Na; Wang, Ai-Guo

2013-07-01

Based on field survey, the biological soil crusts at their stable development stage were collected from the water erosion region, water-wind erosion region, and wind erosion region on the Loess Plateau, aimed to study the effects of the variations of moisture and temperature on the crusts nitrogenase activity (NA). The NA of the crusts in the erosion regions decreased in the order of water erosion region (127.7 micromol x m(-2) x h(-1)) > water-wind erosion region (34.6 micromol x m(-2) x h(-1)) > wind erosion region (6.0 micromol x m(-2) x h(-1)), and the optimal temperature for the crust nitrogen fixation was 35 degrees C, 25 degrees C, and 15 degrees C, respectively. At the optimal temperature and 100% -40% field water-holding capacity, the NA of the crusts from the water erosion and water-wind erosion regions had no significant difference. The NA of the crusts from the wind erosion region was more sensitive to the variation of moisture, showing a dramatic decline when the moisture decreased to 80% field water-holding capacity, and totally lost when the moisture decreased to 20% field water-holding capacity. The differences in the NA of the crusts from the three erosion regions and the responses of the NA to the variations of moisture and temperature were likely associated with the climate, environment, and the crust species composition.

Vegetation morphologic and aerodynamic characteristics reduce aeolian erosion.

Science.gov (United States)

Miri, Abbas; Dragovich, Deirdre; Dong, Zhibao

2017-10-09

Vegetation cover is crucial to controlling aeolian erosion but highly efficient vegetation is critical. How this efficiency is influenced by vegetation response to airflow is not clear. Here we evaluate the responses of Cosmos bipinnatus and Ligustrum lucidum Ait to a range of wind speeds in a wind tunnel. For both species, we calculate shelter effect and sand flux. We show that plant effectiveness in reducing wind speed and sediment transport is linked to their aerodynamic response to airflow which results from their morphology. We demonstrate that in low-density cover the flow-response and resistance of individuals is most critical in the optimal effectiveness of a canopy. Our wind tunnel experiment suggests that vegetation morphology and structure must be priority parameters in facilitating aeolian erosion control.

Control of Eolian soil erosion from waste site surface barriers

International Nuclear Information System (INIS)

Ligotke, M.W.

1994-11-01

Physical models were tested in a wind tunnel to determine optimum surface-ravel admixtures for protecting silt-loam soil from erosion by, wind and saltating, sand stresses. The tests were performed to support the development of a natural-material surface barrier for and waste sites. Plans call for a 2-m deep silt-loam soil reservoir to retain infiltrating water from rainfall and snowmelt. The objective of the study was to develop a gravel admixture that would produce an erosion-resistant surface layer during, periods of extended dry climatic stress. Thus, tests were performed using simulated surfaces representing dry, unvegetated conditions present just after construction, after a wildfire, or during an extended drought. Surfaces were prepared using silt-loam soil mixed with various grades of sand and Travel. Wind-induced surface shear stresses were controlled over the test surfaces, as were saltating, sand mass flow rates and intensities. Tests were performed at wind speeds that approximated and exceeded local 100-year peak gust intensities. Surface armors produced by pea gravel admixtures were shown to provide the best protection from wind and saltating sand stresses. Compared with unprotected silt-loam surfaces, armored surfaces reduced erosion rates by more than 96%. Based in part on wind tunnel results, a pea gravel admixture of 15% will be added to the top 1 in of soil in a prototype barrier under construction in 1994. Field tests are planned at the prototype site to provide data for comparison with wind tunnel results

CFD evaluation of erosion rate around a bridge near a sand dune

Science.gov (United States)

He, Wei; Huang, Ning; Dun, Hongchao; Wang, Wenbo

2017-04-01

This study performs a series of simulations through solving the Navier-Stokes equations and the RNG k-ε turbulence model to investigate the wind erosion rates around a bridge in a desert area with sand dunes. The digital elevation model of sand dunes and the bridge model are obtained respectively from hypsographic map and construction drawings. Through combining them into the CFD software of Fluent the simulation zone was formed. The data of wind speed obtained from field observation is fitted into a logarithm format, which was imported into Fluent model as a inlet wind speed condition. Then, the effect of Dun-Go railway on wind-blown sand movement of the neighbouring environment is simulated. The results exhibit that affected by both the sand dune and bridge, the flow field is in a complex condition. It is also shown that the bridge in upstream of the sand dune will not increase the sand transport rate intensively, but change both wind velocity gradient and turbulence kinetic energy over surface of sand dune. On the other hand, when the bridge is built downstream the sand dune, simulation results show that sand deposition rate would be decreased in reference region downstream the pier.

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

Science.gov (United States)

Ilieva, Diliana; Malinov, Ilia

2014-05-01

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

Compressor Impeller Erosion Resistant Surface Treatment

National Research Council Canada - National Science Library

Riley, Michael

2000-01-01

...). Coatings based on tungsten carbide tantalum carbide. titanium carbide all with a cobalt matrix were evaluated for high velocity particle erosion in conventional wear test studies as well as wind tunnel testing...

Estimated erosion rate at the SRP burial ground

International Nuclear Information System (INIS)

Horton, J.H.; Wilhite, E.L.

1978-04-01

The rate of soil erosion at the Savannah River Plant (SRP) burial ground can be calculated by means of the universal soil loss equation. Erosion rates estimated by the equation are more suitable for long-term prediction than those which could be measured with a reasonable effort in field studies. The predicted erosion rate at the SRP burial ground ranges from 0.0007 cm/year under stable forest cover to 0.38 cm/year if farmed with cultivated crops. These values correspond to 170,000 and 320 years, respectively, to expose waste buried 4 ft deep

Monthly Rainfall Erosivity Assessment for Switzerland

Science.gov (United States)

Schmidt, Simon; Meusburger, Katrin; Alewell, Christine

2016-04-01

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

Wind-eroded silicate as a source of hydrogen peroxide on Mars

DEFF Research Database (Denmark)

Bak, Ebbe Norskov; Merrison, Jonathan P.; Jensen, Svend Knak

-sists of silicates [4] that due to wind erosion has a very fine grained texture. Based on the composition of the surface material and investigations showing that crushing of silicates can give rise to reactive oxygen species [5], we hypothesized that wind erosion of silicates can explain the reactivity of Martian...... soil. Wind-erosion of silicate could thus be one of several causes of the soil’s reactivity. As our experiments show, the globally distributed wind eroded silicate dust can lead to the production of hydrogen peroxide which might explain the reactivity of the Martian soil. The reactivity of eroded...

Integrated universal soil loss equation (USLE and Geographical Information System (GIS for soil erosion estimation in A Sap basin: Central Vietnam

Directory of Open Access Journals (Sweden)

Tung Gia Pham

2018-06-01

Full Text Available Central Vietnam is very susceptible to soil erosion due to its complicated terrain and heavy rainfall. The objective of this study was to quantify soil erosion in the A Sap river basin, A Luoi district, Thua Thien Hue Province, Vietnam, using the Universal Soil Loss Equation (USLE and Geographical Information System (GIS. The results showed that 34% of land area lost accumulated to 10 t ha−1 year−1 while 47% of the total area lost less than 1 t ha−1 year−1. Natural forest land lost the most with an average of about 19 t ha−1 year−1, followed by plantation forest with approximately 7 t ha−1 year−1 and other agricultural lands at 3.70 and 1.45 t ha−1 year−1 for yearly crops and paddy rice, respectively. Soil erosion was most sensitive to the topographic factor (LS, followed by the practice support factor (P, soil erodibility factor (K, cropping management (C, and the rainfall erosivity factor (R. Implications are that changes to the cultivated calendar and implementing intercropping are effective ways to prevent soil erosion in cultivated lands. Furthermore, introducing broad leaves trees for mountainous areas in A Sap basin was the most effective practice in reducing soil erosion. The study also pointed out that the combination of available data sources used with the USLE and GIS technology is a viable option to calculate soil erosion in Central Vietnam, which would allow targeted attention toward a solution is to reduce future soil erosion. Keywords: Central Vietnam, GIS, Soil erosion, USLE

Assessment of wind erosion threat for soils in cadastral area of Hajske

International Nuclear Information System (INIS)

Muchova, Z.; Stredanska, A.

2008-01-01

This contribution illustrates the application of methods of erosion threat assessment in lan adaptation projects. Calculations of the soil erosion index of particular soil blocks are demonstrated for the cadastral area of Hajske. Two methods for assessment of erosion threat have been applied. First the assessment based on the ecological soil-quality units (ESQU) has been performed. Next, the Pasak method for a detailed analysis of the soil erosion threat was applied. Both of the mentioned approaches are recommended for the land adaption projects. Based on the results, the soil blocks have been ranked by their soil erosion threat. (authors)

Design, construction and calibration of a portable boundary layer wind tunnel for field use

Science.gov (United States)

Wind tunnels have been used for several decades to study wind erosion processes. Portable wind tunnels offer the advantage of testing natural surfaces in the field, but they must be carefully designed to insure that a logarithmic boundary layer is formed and that wind erosion processes may develop ...

Soil Erosion: Advanced Crop and Soil Science. A Course of Study.

Science.gov (United States)

Miller, Larry E.

The course of study represents the last of six modules in advanced crop and soil science and introduces the agriculture student to the topic of soil erosion. Upon completion of the two day lesson, the student will be able to: (1) define conservation, (2) understand how erosion takes place, and (3) list ways of controlling wind and water erosion.…

Modeling real-time balancing power demands in wind power systems using stochastic differential equations

International Nuclear Information System (INIS)

Olsson, Magnus; Perninge, Magnus; Soeder, Lennart

2010-01-01

The inclusion of wind power into power systems has a significant impact on the demand for real-time balancing power due to the stochastic nature of wind power production. The overall aim of this paper is to present probabilistic models of the impact of large-scale integration of wind power on the continuous demand in MW for real-time balancing power. This is important not only for system operators, but also for producers and consumers since they in most systems through various market solutions provide balancing power. Since there can occur situations where the wind power variations cancel out other types of deviations in the system, models on an hourly basis are not sufficient. Therefore the developed model is in continuous time and is based on stochastic differential equations (SDE). The model can be used within an analytical framework or in Monte Carlo simulations. (author)

The Use of a Code-generating System for the Derivation of the Equations for Wind Turbine Dynamics

Science.gov (United States)

Ganander, Hans

2003-10-01

For many reasons the size of wind turbines on the rapidly growing wind energy market is increasing. Relations between aeroelastic properties of these new large turbines change. Modifications of turbine designs and control concepts are also influenced by growing size. All these trends require development of computer codes for design and certification. Moreover, there is a strong desire for design optimization procedures, which require fast codes. General codes, e.g. finite element codes, normally allow such modifications and improvements of existing wind turbine models. This is done relatively easy. However, the calculation times of such codes are unfavourably long, certainly for optimization use. The use of an automatic code generating system is an alternative for relevance of the two key issues, the code and the design optimization. This technique can be used for rapid generation of codes of particular wind turbine simulation models. These ideas have been followed in the development of new versions of the wind turbine simulation code VIDYN. The equations of the simulation model were derived according to the Lagrange equation and using Mathematica®, which was directed to output the results in Fortran code format. In this way the simulation code is automatically adapted to an actual turbine model, in terms of subroutines containing the equations of motion, definitions of parameters and degrees of freedom. Since the start in 1997, these methods, constituting a systematic way of working, have been used to develop specific efficient calculation codes. The experience with this technique has been very encouraging, inspiring the continued development of new versions of the simulation code as the need has arisen, and the interest for design optimization is growing.

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...

Wind tunnel simulation of Martian sand storms

Science.gov (United States)

Greeley, R.

1980-01-01

The physics and geological relationships of particles driven by the wind under near Martian conditions were examined in the Martian Surface Wind Tunnel. Emphasis was placed on aeolian activity as a planetary process. Threshold speeds, rates of erosion, trajectories of windblown particles, and flow fields over various landforms were among the factors considered. Results of experiments on particles thresholds, rates of erosion, and the effects of electrostatics on particles in the aeolian environment are presented.

The development of U. S. soil erosion prediction and modeling

Directory of Open Access Journals (Sweden)

John M. Laflen

2013-09-01

Full Text Available Soil erosion prediction technology began over 70 years ago when Austin Zingg published a relationship between soil erosion (by water and land slope and length, followed shortly by a relationship by Dwight Smith that expanded this equation to include conservation practices. But, it was nearly 20 years before this work's expansion resulted in the Universal Soil Loss Equation (USLE, perhaps the foremost achievement in soil erosion prediction in the last century. The USLE has increased in application and complexity, and its usefulness and limitations have led to the development of additional technologies and new science in soil erosion research and prediction. Main among these new technologies is the Water Erosion Prediction Project (WEPP model, which has helped to overcome many of the shortcomings of the USLE, and increased the scale over which erosion by water can be predicted. Areas of application of erosion prediction include almost all land types: urban, rural, cropland, forests, rangeland, and construction sites. Specialty applications of WEPP include prediction of radioactive material movement with soils at a superfund cleanup site, and near real-time daily estimation of soil erosion for the entire state of Iowa.

Microbiology of Wind-eroded Sediments: Current Knowledge and Future Research Directions

Science.gov (United States)

Wind erosion is a threat to the sustainability and productivity of soils that takes place at local, regional, and global scales. Current estimates of cost of wind erosion have not included the costs associated with the loss of soil biodiversity and reduced ecosystem functions. Microorganisms carrie...

Wind tunnel tests of biodegradable fugitive dust suppressants being considered to reduce soil erosion by wind at radioactive waste construction sites

International Nuclear Information System (INIS)

Ligotke, M.W.; Dennis, G.W.; Bushaw, L.L.

1993-10-01

Wind tunnel tests were performed of three fugitive dust control agents derived from potato and sugar beet products. These materials are being considered for use as dust suppressants to reduce the potential for transport of radioactive materials by wind from radioactive waste construction and remediation sites. Soil and dust control agent type, solution concentrations, application quantities, aging (or drying) conditions, surface disturbance, and wind and saltating sand eolian erosive stresses were selected and controlled to simulate application and exposure of excavated soil surfaces in the field. A description of the tests, results, conclusions, and recommendations are presented in this report. The results of this study indicate that all three dust control agents can protect exposed soil surfaces from extreme eolian stresses. It is also clear that the interaction and performance of each agent with various soil types may differ dramatically. Thus, soils similar to that received from ML should be best protected by high concentration (∼2.5%) solutions of potato starch at low water application levels (∼1 to 2 L/m 2 ). Because the effectiveness of PS on this soil type is degraded after a moderate amount of simulated rainfall, other options or additives should be considered if surfaces are to be protected for long intervals or during periods of intermittent rainfall and hot, windy conditions. On the other hand, XDCA should be considered when excavating sandy soils. It should be noted, however, that because the Hanford soil test results are based on a small number of tests, it would be prudent to perform additional tests prior to selecting a fugitive dust control agent for use at the Hanford Site. While fermented potato waste was not the best fixative used on either soil, it did perform reasonably well on both soil types (better than XDCA on Idaho soil and better than PS on Hanford soil)

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

Science.gov (United States)

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

2012-10-01

Sediment transport from steep slopes and agricultural lands into the Uluabat Lake (a RAMSAR site) by the Mustafakemalpasa (MKP) River is a serious problem within the river basin. Predictive erosion models are useful tools for evaluating soil erosion and establishing soil erosion management plans. The Revised Universal Soil Loss Equation (RUSLE) function is a commonly used erosion model for this purpose in Turkey and the rest of the world. This research integrates the RUSLE within a geographic information system environment to investigate the spatial distribution of annual soil loss potential in the MKP River Basin. The rainfall erosivity factor was developed from local annual precipitation data using a modified Fournier index: The topographic factor was developed from a digital elevation model; the K factor was determined from a combination of the soil map and the geological map; and the land cover factor was generated from Landsat-7 Enhanced Thematic Mapper (ETM) images. According to the model, the total soil loss potential of the MKP River Basin from erosion by water was 11,296,063 Mg year(-1) with an average soil loss of 11.2 Mg year(-1). The RUSLE produces only local erosion values and cannot be used to estimate the sediment yield for a watershed. To estimate the sediment yield, sediment-delivery ratio equations were used and compared with the sediment-monitoring reports of the Dolluk stream gauging station on the MKP River, which collected data for >41 years (1964-2005). This station observes the overall efficiency of the sediment yield coming from the Orhaneli and Emet Rivers. The measured sediment in the Emet and Orhaneli sub-basins is 1,082,010 Mg year(-1) and was estimated to be 1,640,947 Mg year(-1) for the same two sub-basins. The measured sediment yield of the gauge station is 127.6 Mg km(-2) year(-1) but was estimated to be 170.2 Mg km(-2) year(-1). The close match between the sediment amounts estimated using the RUSLE

Simplified equations for the rotational speed response to inflow velocity variation in fixed-pitch small wind turbines

Energy Technology Data Exchange (ETDEWEB)

Suzuki, H; Hasegawa, Y, E-mail: hsuzuki@nitech.ac.jp [Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan)

2015-02-01

We propose simplified equations for the rotational speed response to inflow velocity variation in fixed-pitch small wind turbines. The present formulation is derived by introducing a series expansion for the torque coefficient at the constant tip-speed ratio. By focusing on the first- and second-order differential coefficients of the torque coefficient, we simplify the original differential equation. The governing equation based only on the first-order differential coefficient is found to be linear, whereas the second-order differential coefficient introduces nonlinearity. We compare the numerical solutions of the three governing equations for rotational speed in response to sinusoidal and normal-random variations of inflow velocity. The linear equation gives accurate solutions of amplitude and phase lag. Nonlinearity occurs in the mean value of rotational speed variation. We also simulate the rotational speed in response to a step input of inflow velocity using the conditions of two previous studies, and note that the form of this rotational speed response is a system of first-order time lag. We formulate the gain and time constant for this rotational speed response. The magnitude of the gain is approximately three when the wind turbine is operated at optimal tip-speed ratio. We discuss the physical meaning of the derived time constant. (paper)

Regionalization of monthly rainfall erosivity patternsin Switzerland

Science.gov (United States)

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

2016-10-01

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

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.

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

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

Science.gov (United States)

Kapicka, Jiri

2015-04-01

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

Dynamic Study of Soil Erosion in Greater Khingan Forest

OpenAIRE

Wei Li; Wenyi Fan; Xuegang Mao; Xiaojie Wang

2015-01-01

Based on the amended model of RUSLE universal soil loss equation and GIS technology, combined with the natural geographical features of Great Khingan, it has conducted quantitative analysis of the factor in Soil loss equation. Uses 2000 and 2010 years TM images classification are land uses/cover type figure, we gets all factors values of space distribution in the RUSLE model, gets soil erosion volume estimates data and soil erosion strength distribution figure based on grid cell data and obta...

Erosivity of rainfall in Lages, Santa Catarina, Brazil

Directory of Open Access Journals (Sweden)

Jefferson Schick

2014-12-01

Full Text Available The erosive capacity of rainfall can be expressed by an index and knowing it allows recommendation of soil management and conservation practices to reduce water erosion. The objective of this study was to calculate various indices of rainfall erosivity in Lages, Santa Catarina, Brazil, identify the best one, and discover its temporal distribution. The study was conducted at the Center of Agricultural and Veterinary Sciences, Lages, Santa Catarina, using daily rainfall charts from 1989 to 2012. Using the computer program Chuveros , 107 erosivity indices were obtained, which were based on maximum intensity in 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 70, 80, 90, 100, 110, 120, 135, 150, 165, 180, 210, and 240 min of duration and on the combination of these intensities with the kinetic energy obtained by the equations of Brown & Foster, Wagner & Massambani, and Wischmeier & Smith. The indices of the time period from 1993 to 2012 were correlated with the respective soil losses from the standard plot of the Universal Soil Loss Equation (USLE in order to select the erosivity index for the region. Erosive rainfall accounted for 83 % of the mean annual total volume of 1,533 mm. The erosivity index (R factor of rainfall recommended for Lages is the EI30, whose mean annual value is 5,033 MJ mm ha-1 h-1, and of this value, 66 % occurs from September to February. Mean annual erosivity has a return period estimated at two years with a 50 % probability of occurrence.

Challenges in soil erosion research and prediction model development

Science.gov (United States)

Quantification of soil erosion has been traditionally considered as a surface hydrologic process with equations for soil detachment and sediment transport derived from the mechanics and hydraulics of the rainfall and surface flow. Under the current erosion modeling framework, the soil has a constant...

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.

Short review of runoff and erosion physically based models

Directory of Open Access Journals (Sweden)

Gabrić Ognjen

2015-01-01

Full Text Available Processes of runoff and erosion are one of the main research subjects in hydrological science. Based on the field and laboratory measurements, and analogous with development of computational techniques, runoff and erosion models based on equations which describe the physics of the process are also developed. Several models of runoff and erosion which describes entire process of genesis and sediment transport on the catchment are described and compared.

Sand transport, erosion and granular electrification

DEFF Research Database (Denmark)

Merrison, J.P.

2012-01-01

is expanding our current understanding and outline the areas of advancement needed in the future. Presentation is made of current models for wind driven detachment/entrainment and the transport rates of sand and dust, including the effects of contact induced grain electrification. This ubiquitous phenomenon...... can affect grain transport through the generation of intense electric fields and processes of electrostatic assembly. Importantly the transport of sand is characterized by saltation, which is known to be an active process for erosion and therefore a source for dust and sand formation. Using novel...... erosion simulation techniques the link between grain transport rates and erosion rates has been quantified. Furthermore this can be linked to production rates for dust and has been associated with chemical and mineral alteration through a process of mechanical activation of fractured surfaces. This work...

An Integrated Assessment Framework of Offshore Wind Power Projects Applying Equator Principles and Social Life Cycle Assessment

Directory of Open Access Journals (Sweden)

Yu-Che Tseng

2017-10-01

Full Text Available This paper reviews offshore wind power project finance and provides an integrated assessment that employs Equator Principles, life cycle assessment, risk assessment, materiality analysis, credit assessment, and ISAE 3000 assurance. We have not seen any comprehensive review papers or book chapters that covers the entire offshore wind power project finance process. We also conducted an SWancor Formosa Phase 1 case study to illustrate the application of integrated assessment to better assist policymakers, wind farm developers, practitioners, potential investors and observers, and stakeholders in their decisions. We believe that this paper can form part of the effort to reduce information asymmetry and the transaction costs of wind power project finance, as well as mobilize green finance investments from the financial sector to renewable energy projects to achieve a national renewable energy policy.

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

Science.gov (United States)

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.

Control of eolic erosion in a coal Port, by means of re-vegetation of arid areas and operational procedures

International Nuclear Information System (INIS)

Velasquez Pilar

1992-01-01

To the phenomenon of haulage of floor particles for the wind is known as erosion by deflation, and one in the ways of eolic erosion existent, although many authors constitutes they refer to her as eolic erosion. The eolic erosion includes the movement processes, transport, separation and deposition, it can present in any area that presents the following conditions: 1) Soil dry and loose until certain finely divided degree, 2) flat surface with little or any vegetable cover, 3) quite extensive land 4) sufficiently strong wind to transport the earth particles. It is considered that to begin the movement of particles 0.1 mm of diameter winds they are needed to 30 cm of height of 4,4m/s (FAO, 1961). All these conditions are presented in Port Bolivar in more or smaller measure. In port Bolivar two main groups of areas have been identified in process of material movement

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)

A new noise erosion operator for anisotropic diffusion

Institute of Scientific and Technical Information of China (English)

蔡超; 丁名跃; 周成平; 张天序

2004-01-01

A noise erosion operator based on partial differential equation (PDE) is introduced, which has an excellent ability of noise removal and edge preservation for two-dimensional (2D) gradient data. The operator is applied to estimate a new diffusion coefficient. Experimental results demonstrate that anisotropic diffusion based on this new erosion operator can efficiently reduce noise and sharpen object boundaries.

Nourishment of perched sand dunes and the issue of erosion control in the Great Lakes

Science.gov (United States)

Marsh, William M.

1990-09-01

Although limited in coverage, perched sand dunes situated on high coastal bluffs are considered the most prized of Great Lakes dunes. Grand Sable Dunes on Lake Superior and Sleeping Bear Dunes on Lake Michigan are featured attractions of national lakeshores under National Park Service management. The source of sand for perched dunes is the high bluff along their lakeward edge. As onshore wind crosses the bluff, flow is accelerated upslope, resulting in greatly elevated levels of wind stress over the slope brow. On barren, sandy bluffs, wind erosion is concentrated in the brow zone, and for the Grand Sable Bluff, it averaged 1 m3/yr per linear meter along the highest sections for the period 1973 1983. This mechanism accounts for about 6,500 m3 of sand nourishment to the dunefield annually and clearly has been the predominant mechanism for the long-term development of the dunefield. However, wind erosion and dune nourishment are possible only where the bluff is denuded of plant cover by mass movements and related processes induced by wave erosion. In the Great Lakes, wave erosion and bluff retreat vary with lake levels; the nourishment of perched dunes is favored by high levels. Lake levels have been relatively high for the past 50 years, and shore erosion has become a major environmental issue leading property owners and politicians to support lake-level regulation. Trimming high water levels could reduce geomorphic activity on high bluffs and affect dune nourishment rates. Locally, nourishment also may be influenced by sediment accumulation associated with harbor protection facilities and by planting programs aimed at stabilizing dunes.

Solid particle erosion of polymers and composites

Science.gov (United States)

Friedrich, K.; Almajid, A. A.

2014-05-01

After a general introduction to the subject of solid particle erosion of polymers and composites, the presentation focusses more specifically on the behavior of unidirectional carbon fiber (CF) reinforced polyetheretherketone (PEEK) composites under such loadings, using different impact conditions and erodents. The data were analyzed on the basis of a newly defined specific erosive wear rate, allowing a better comparison of erosion data achieved under various testing conditions. Characteristic wear mechanisms of the CF/PEEK composites consisted of fiber fracture, matrix cutting and plastic matrix deformation, the relative contribution of which depended on the impingement angles and the CF orientation. The highest wear rates were measured for impingement angles between 45 and 60°. Using abrasion resistant neat polymer films (in this case PEEK or thermoplastic polyurethane (TPU) ones) on the surface of a harder substrate (e.g. a CF/PEEK composite plate) resulted in much lower specific erosive wear rates. The use of such polymeric films can be considered as a possible method to protect composite surfaces from damage caused by minor impacts and erosion. In fact, they are nowadays already successfully applied as protections for wind energy rotor blades.

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

Science.gov (United States)

Kapicka, Jiri; Zizala, Daniel

2013-04-01

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

Erodibility of waste (Loess) soils from construction sites under water and wind erosional forces.

Science.gov (United States)

Tanner, Smadar; Katra, Itzhak; Argaman, Eli; Ben-Hur, Meni

2018-03-01

Excess soils from construction sites (waste soils) become a problem when exposed to soil erosion by water or wind. Understanding waste soil erodibility can contribute to its proper reuse for various surface applications. The general objective of the study was to provide a better understanding of the effects of soil properties on erodibility of waste soils excavated from various depths in a semiarid region under rainfall and wind erosive forces. Soil samples excavated from the topsoil (0-0.3m) and subsoil layers (0.3-0.9 and >1m depths) were subjected to simulated rainfall and wind. Under rainfall erosive forces, the subsoils were more erodible than the topsoil, in contrast to the results obtained under wind erosive forces. Exchangeable sodium percentage was the main factor controlling soil erodibility (K i ) under rainfall, and a significant logarithmic regression line was found between these two parameters. In addition, a significant, linear regression was found between K i and slaking values for the studied soil samples, suggesting that the former can be predicted from the latter. Soil erodibility under wind erosion force was controlled mainly by the dry aggregate characteristics (mean weight diameter and aggregate density): their higher values in the subsoil layers resulted in lower soil erodibility compared to the topsoil. Copyright © 2017 Elsevier B.V. All rights reserved.

Erosion Assessment Modeling Using the Sateec Gis Model on the Prislop Catchment

Directory of Open Access Journals (Sweden)

Damian Gheorghe

2014-05-01

Full Text Available The Sediment Assessment Tool for Effective Erosion Control (SATEEC acts as an extension for ArcView GIS 3, with easy to use commands. The erosion assessment is divided into two modules that consist of Universal Soil Loss Equation (USLE for sheet/rill erosion and the nLS/USPED modeling for gully head erosion. The SATEEC erosion modules can be successfully implemented for areas where sheet, rill and gully erosion occurs, such as the Prislop Catchment. The enhanced SATEEC system does not require experienced GIS users to operate the system therefore it is suitable for local authorities and/or students not so familiar with erosion modeling.

EVALUATION OF SOIL EROSION IN REGHIN HILLS USING THE USLE METHOD

Directory of Open Access Journals (Sweden)

J. SZILAGYI

2016-03-01

Full Text Available Soil erosion is one of the main causes of degradation of large areas of agricultural land, causing great economic loss by removing fertile soil. The Universal Soil Loss Equation (USLE predicts the long term average annual rate of erosion on a field slope based on rainfall pattern, soil type, topography, crop system and management practices but does not however predict the soil loss resulting from gully erosion.

Study of calibration equations of {sup 137}Cs methodology for soil erosion determination; Estudo de equacoes de calibracao para metodologia do {sup 137}Cs de determinacao da erosao de solos

Energy Technology Data Exchange (ETDEWEB)

Santos, Elias Antunes dos

2001-02-01

Using the method of {sup 137} Cs and gamma-ray spectrometry, soil samples of two plots erosion were studied at Londrina city. the soil class studied was a dystrophic dark red soil (LRd), with erosion indexes measured by Agronomic Institute of Parana State (IAPAR) using a conventional method, since 1976. Through the percentage reduction of {sup 137} Cs related to the reference site, the soil losses were calculated using the proportional, mass balance and profile distribution models. Making the correlation between the {sup 137} Cs concentrations and the erosion measured by IAPAR, two calibration equations were obtained and applied to the data set measured in the basin of the Unda river and compared to those models in the literature. As reference region, was chosen a natural forest located close to the plots. The average inventory of {sup 137} Cs was 555{+-} 16 Bq.m{sup -2}. The inventories of the erosion plots varied from 112 to 136 Bq.m{sup -2} for samples collected until 30 cm depth. The erosion rates estimated by the models varied from 64 to 85 ton.ha{sup -1}.yr{sup -1} for the proportional and profile distribution models, respectively, and 137 to 165 ton.ha{sup -1} for the mass balance model, while the measured erosion obtained by IAPAR was 86 ton.ha{sup -1}.yr{sup -1}. From the two calibration equations obtained, the one that take into account the {sup 137} Cs distribution with the soil profile was that showed the best consistence with the erosion rated for the basin of the Unda river (same soil class) in the range from 4 to 48 ton.ha{sup -1}.yr{sup -1}, while the proportional and profile distribution models applied rates from 7 to 45 ton.ha{sup -1}.yr{sup -1} and 6 to 69 ton.ha{sup -1}.yr{sup -1}, respectively. (author)

A new concept for stainless steels ranking upon the resistance to cavitation erosion

Science.gov (United States)

Bordeasu, I.; Popoviciu, M. O.; Salcianu, L. C.; Ghera, C.; Micu, L. M.; Badarau, R.; Iosif, A.; Pirvulescu, L. D.; Podoleanu, C. E.

2017-01-01

In present, the ranking of materials as their resistance to cavitation erosion is obtained by using laboratory tests finalized with the characteristic curves mean depth erosion against time MDE(t) and mean depth erosion rate against time MDER(t). In some previous papers, Bordeasu and co-workers give procedures to establish exponential equation representing the curves, with minimum scatter of the experimental obtained results. For a given material, both exponential equations MDE(t) and MDER(t) have the same values for the parameters of scale and for the shape one. For the ranking of materials is sometimes important to establish single figure. Till now in Timisoara Polytechnic University Cavitation Laboratory were used three such numbers: the stable value of the curve MDER(t), the resistance to cavitation erosion (Rcav ≡ 1/MDERstable) and the normalized cavitation resistance Rns which is the rate between vs = MDERstable for the analyzed material and vse= MDERse the mean depth erosion rate for the steel OH12NDL (Rns = vs/vse ). OH12NDL is a material used for manufacturing the blades of numerous Kaplan turbines in Romania for which both cavitation erosion laboratory tests and field measurements of cavitation erosions are available. In the present paper we recommend a new method for ranking the materials upon cavitation erosion resistance. This method uses the scale and shape parameters of the exponential equations which represents the characteristic cavitation erosion curves. Till now the method was applied only for stainless steels. The experimental results show that the scale parameter represents an excellent method for ranking the stainless steels. In the future this kind of ranking will be tested also for other materials especially for bronzes used for manufacturing ship propellers.

I Got Them Dust Bowl Blues: Wind Erosion in the Music of the Southern Great Plains

Science.gov (United States)

Lee, J. A.

2017-12-01

This paper deals with the role of wind erosion and blowing dust on the music of the Dust Bowl region, a portion of the southern Great Plains of the United States. A defining characteristic of the region is dust storms, and in the 1930s, severe dust storms created dramatic images that came to symbolize all of the economic, social and environmental hardships suffered by the people during the 1930s. The music of the time, by Woody Guthrie and others, suggested that the region was being destroyed, never to recover. The region was resilient, however, and in recent decades, dust has been depicted in songs either as an adversity to be endured or simply as a normal part of life in the area. It may be that blowing dust has become a defining characteristic of the region because of a somewhat warped sense of pride in living in an often-difficult environment.

Active Anti-erosion Protection Strategy in Tamarisk (Tamarix aphylla)

Science.gov (United States)

Han, Zhiwu; Yin, Wei; Zhang, Junqiu; Niu, Shichao; Ren, Luquan

2013-12-01

Plants have numerous active protection strategies for adapting to complex and severe environments. These strategies provide endless inspiration for extending the service life of materials and machines. Tamarisk (Tamarix aphylla), a tree that thrives in raging sandstorm regions, has adapted to blustery conditions by evolving extremely effective and robust erosion resistant characteristics. However, the relationships among its surface cracks, internal histology and biomechanics, such as cracks, rings, cells, elasticity modulus and growth stress, which account for its erosion resistance, remain unclear. This present study reveals that the directionally eccentric growth rings of tamarisk, which are attributed to reduced stress and accelerated cell division, promote the formation of surface cracks. The windward rings are more extensive than the leeward side rings. The windward surfaces are more prone to cracks, which improves erosion resistance. Our data provide insight into the active protection strategy of the tamarisk against wind-sand erosion.

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

Science.gov (United States)

Kong, Bo; Yu, Huan

2013-01-01

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

Improved Soil Erosion and Sediment Transport in GSSHA

Science.gov (United States)

2010-08-01

the USLE soil erodibility factor (0-1), soil cropping factor (0-1) and conservation factor (0-1) in the development by Julien (1995). The use of one...factor K represents a departure from Julien (1995), who used all three factors from the Universal Soil Loss Equation ( USLE ). This departure is justi...runoff using a research-quality data set. BACKGROUND: GSSHA simulates overland soil erosion and outputs erosion and deposition for any size class of

Numerical modelling of erosion and sedimentation around offshore pipelines

NARCIS (Netherlands)

van Beek, F.A.; Wind, H.G.

1990-01-01

In this paper a numerical model is presented for the description of the erosion and sedimentation near pipelines on the sea bottom. The model is based on the Navier-Stokes equations and the equation of motion and continuity of sediment. The results of the simulations have been compared with the

7 CFR 610.11 - Purpose and scope.

Science.gov (United States)

2010-01-01

... under which NRCS will utilize the USLE, the revised universal soil loss equation (RUSLE), and the WEQ. ... AGRICULTURE CONSERVATION OPERATIONS TECHNICAL ASSISTANCE Soil Erosion Prediction Equations § 610.11 Purpose... by the Natural Resources Conservation Service (NRCS) to predict soil erosion due to water and wind...

Estimating erosion in a riverine watershed: Bayou Liberty-Tchefuncta River in Louisiana.

Science.gov (United States)

Martin, August; Gunter, James T; Regens, James L

2003-01-01

GOAL, SCOPE, BACKGROUND: Sheet erosion from agricultural, forest and urban lands may increase stream sediment loads as well as transport other pollutants that adversely affect water quality, reduce agricultural and forest production, and increase infrastructure maintenance costs. This study uses spatial analysis techniques and a numerical modeling approach to predict areas with the greatest sheet erosion potential given different soils disturbance scenarios. A Geographic Information System (GIS) and the Universal Soil Loss Equation (USLE) were used to estimate sheet erosion from 0.64 ha parcels of land within the watershed. The Soil Survey of St. Tammany Parish, Louisiana was digitized, required soil attributes entered into the GIS database, and slope factors determined for each 80 x 80 meter parcel in the watershed. The GIS/USLE model used series-specific erosion K factors, a rainfall factor of 89, and a GIS database of scenario-driven cropping and erosion control practice factors to estimate potential soil loss due to sheet erosion. A general trend of increased potential sheet erosion occurred for all land use categories (urban, agriculture/grasslands, forests) as soil disturbance increases from cropping, logging and construction activities. Modeling indicated that rapidly growing urban areas have the greatest potential for sheet erosion. Evergreen and mixed forests (production forest) had lower sheet erosion potentials; with deciduous forests (mostly riparian) having the least sheet erosion potential. Erosion estimates from construction activities may be overestimated because of the value chosen for the erosion control practice factor. This study illustrates the ease with which GIS can be integrated with the Universal Soil Loss Equation to identify areas with high sheet erosion potential for large scale management and policy decision making. The GIS/USLE modeling approach used in this study offers a quick and inexpensive tool for estimating sheet erosion within

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

Science.gov (United States)

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

2015-12-01

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

Dust records in the Pleistocene sediments of Fraser Island: palaeoclimatic reconstruction of wind erosion over the last 600 ka

International Nuclear Information System (INIS)

Longmore, M.E.; McTainsh, G.H.

1997-01-01

Full text: Pleistocene lake sediments from a relic perched freshwater lake on Fraser Island have been found to date back to ca.600 ka using U/Th analysis of the organics. This sequence is one of the three longest terrestrial records of environmental change in Australia and the contained evidence of vegetation, fire and lake level changes (Longmore and Heijnis, 1996) and is an invaluable contribution to palaeoclimatic reconstruction. A younger sequence, dated by conventional radiocarbon analysis, has 6.5 m of continuous organic sedimentation from ca. 30 ka to the present. The last 8.5 ka has been analysed in detail, showing a mid-Holocene 'dry' period (Longmore, 1996). Continental aeolian dust from extreme wind erosional events has been measured in modern atmospheres (McTainsh, 1989; Knight et al., 1995) and deep sea cores (Hesse, 1994), but the terrestrial record of wind erosion during the Pleistocene is sparse. We will report on a pilot project to determine the presence of aeolian dust from extreme wind erosional events in the past in the sediments of Fraser Island lakes. Due to the highly weathered, well-sorted, siliceous nature of the dune sands forming the Island and the highly organic nature of the lake sediments (80-95% LOI), these are some of the few terrestrial sequences that permit separation of aeolian dust from local catchment materials. In the future, oxygen isotope and XRD analysis of the extracted dust will allow the most likely source of the entrained material to be determined and thus provide further evidence as to the wind regime during the last 600ka and 30ka respectively. The separation of dust from these terrestrial sequences is a major achievement and potentially may make a significant contribution to global palaeoclimatic models

Scour depth estimation using an equation based on wind tunnel experiments

Directory of Open Access Journals (Sweden)

Tsutsui Takayuki

2016-01-01

Full Text Available Scour is the result of degradation and aggradation by wind or moving fluid in the front and back of a pole standing in sand, respectively, and is often observed at the bottom of bridge piers in rivers. In this study, we propose a method of estimating the scour depth around a cylindrical structure standing in sand. The relationships among the depth of the scour, the aspect ratio of the structure (= height/diameter, the fluid velocity, and the sand properties (particle size and density were determined experimentally using a wind tunnel. The experiments were carried out under clear-water scour conditions. In the experiments, the aspect ratio of the cylindrical structure, the fluid velocity, and the sand particle size were varied systematically. The diameters of the structure were 20, 40, and 60 mm, and the aspect ratio was varied from 0.25 to 3.0. Sand particles of four sizes (200, 275, 475, and 600 μm were used in the experiment, and the velocity was varied from 4 to 11 m/s. The depth and radius of the scour were measured. As a result, we have developed an equation for estimating the scour depth that uses the aspect ratio, fluid velocity, and sand particle size as parameters.

Predicting soil erosion risk at the Alqueva dam watershed

OpenAIRE

Ferreira, Vera; Panagopoulos, Thomas

2012-01-01

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

Vegetation in drylands: Effects on wind flow and aeolian sediment transport

Science.gov (United States)

Drylands are characterised by patchy vegetation, erodible surfaces and erosive aeolian processes. Empirical and modelling studies have shown that vegetation elements provide drag on the overlying airflow, thus affecting wind velocity profiles and altering erosive dynamics on desert surfaces. However...

[Species-associated differences in foliage-root coupling soil-reinforcement and anti-erosion].

Science.gov (United States)

Liu, Fu-quan; Liu, Jing; Nao, Min; Yao, Xi-jun; Zheng, Yong-gang; Li, You-fang; Su, Yu; Wang, Chen-jia

2015-02-01

This paper took four kinds of common soil and water conservation plants of the study area, Caragana microphylla, Salix psammophila, Artemisia sphaerocephala and Hippophae rhamnides at ages of 4 as the research object. Thirteen indicators, i.e., single shrub to reduce wind velocity ration, shelterbelt reducing wind velocity ration, community reducing wind velocity ration, taproot tensile strength, representative root constitutive properties, representative root elasticity modulus, lateral root branch tensile strength, accumulative surface area, root-soil interface sheer strength, interface friction coefficient, accumulative root length, root-soil composite cohesive, root-soil composite equivalent friction angle, reflecting the characteristics of windbreak and roots, were chose to evaluate the differences of foliage-root coupling soil-reinforcement and anti-erosion among four kinds of plants by analytic hierarchy process (AHP) under the condition of spring gale and summer rainstorm, respectively. The results showed the anti-erosion index of foliage-root coupling was in the sequence of S. psammophila (0.841) > C. microphylla (0.454) > A. sphaerocephala (-0.466) > H. rhamnides (-0.829) in spring gale, and C. microphylla (0.841) > S. psammophila (0. 474) > A. sphaerocephala (-0.470) > H. rhamnides (-0.844) in summer rainstorm. S. psammophila could be regarded as one of the most important windbreak and anti-erosion species, while C. microphylla could be the most valuable soil and water conservation plant for the study area.

Estimation of water erosion rates using RUSLE3D in Alicante province (Spain)

OpenAIRE

Garcia Rodríguez, Jose Luis; Giménez Suárez, Martín Cruz; Arraiza Bermudez-Cañete, Maria Paz

2015-01-01

The purpose of this study was the estimation of current and potential water erosion rates in Alicante Province using RUSLE3D (Revised Universal Soil Loss Equation-3D) model with Geographical Information System (GIS) support by request from the Valencia Waste Energy Use. RUSLE3D uses a new methodology for topographic factor estimation (LS factor) based on the impact of flow convergence allowing better assessment of sediment distribution detached by water erosion. In RUSLE3D equation, the effec...

Modelling soil erosion at European scale: towards harmonization and reproducibility

Science.gov (United States)

Bosco, C.; de Rigo, D.; Dewitte, O.; Poesen, J.; Panagos, P.

2015-02-01

Soil erosion by water is one of the most widespread forms of soil degradation. The loss of soil as a result of erosion can lead to decline in organic matter and nutrient contents, breakdown of soil structure and reduction of the water-holding capacity. Measuring soil loss across the whole landscape is impractical and thus research is needed to improve methods of estimating soil erosion with computational modelling, upon which integrated assessment and mitigation strategies may be based. Despite the efforts, the prediction value of existing models is still limited, especially at regional and continental scale, because a systematic knowledge of local climatological and soil parameters is often unavailable. A new approach for modelling soil erosion at regional scale is here proposed. It is based on the joint use of low-data-demanding models and innovative techniques for better estimating model inputs. The proposed modelling architecture has at its basis the semantic array programming paradigm and a strong effort towards computational reproducibility. An extended version of the Revised Universal Soil Loss Equation (RUSLE) has been implemented merging different empirical rainfall-erosivity equations within a climatic ensemble model and adding a new factor for a better consideration of soil stoniness within the model. Pan-European soil erosion rates by water have been estimated through the use of publicly available data sets and locally reliable empirical relationships. The accuracy of the results is corroborated by a visual plausibility check (63% of a random sample of grid cells are accurate, 83% at least moderately accurate, bootstrap p ≤ 0.05). A comparison with country-level statistics of pre-existing European soil erosion maps is also provided.

Quantification Of Erosion Rates Of Agriculturally Used Soils By Artificial

Science.gov (United States)

Jha, Abhinand

2010-05-01

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

Ash particle erosion on steam boiler convective section

Energy Technology Data Exchange (ETDEWEB)

Meuronen, V

1998-12-31

In this study, equations for the calculation of erosion wear caused by ash particles on convective heat exchanger tubes of steam boilers are presented. A new, three-dimensional test arrangement was used in the testing of the erosion wear of convective heat exchanger tubes of steam boilers. When using the sleeve-method, three different tube materials and three tube constructions could be tested. New results were obtained from the analyses. The main mechanisms of erosion wear phenomena and erosion wear as a function of collision conditions and material properties have been studied. Properties of fossil fuels have also been presented. When burning solid fuels, such as pulverized coal and peat in steam boilers, most of the ash is entrained by the flue gas in the furnace. In bubbling and circulating fluidized bed boilers, particle concentration in the flue gas is high because of bed material entrained in the flue gas. Hard particles, such as sharp edged quartz crystals, cause erosion wear when colliding on convective heat exchanger tubes and on the rear wall of the steam boiler. The most important ways to reduce erosion wear in steam boilers is to keep the velocity of the flue gas moderate and prevent channelling of the ash flow in a certain part of the cross section of the flue gas channel, especially near the back wall. One can do this by constructing the boiler with the following components. Screen plates can be used to make the velocity and ash flow distributions more even at the cross-section of the channel. Shield plates and plate type constructions in superheaters can also be used. Erosion testing was conducted with three types of tube constructions: a one tube row, an in- line tube bank with six tube rows, and a staggered tube bark with six tube rows. Three flow velocities and two particle concentrations were used in the tests, which were carried out at room temperature. Three particle materials were used: quartz, coal ash and peat ash particles. Mass loss

Numerical study of a mathematical model of internal erosion of soil

Science.gov (United States)

Sibin, A.

2017-10-01

The process of internal erosion in a three-phase saturated soil is studied. A mathematical model describing the process consists of the equations of mass conservation, Darcy’s law and equation for capillary pressure. The original system of equations is reduced to a system of three equations for porosity, pressure and water saturation. Obtained equation for the water saturation is degenerate. The degenerate problem in an one-dimensional domain is solved numerically using the finite-difference method.

Validation of the erosion map for spherical particle impacts on glass

NARCIS (Netherlands)

Verspui, M.A.; Slikkerveer, P.J.; Skerka, G.J.E.; Oomen, I.; With, de G.

1998-01-01

Hard spherical particles may exhibit a variation in impact damage on a softer target depending on the particle diameter and particle velocity. In this paper quantitative equations will be derived for these transitions in material behaviour. These equations have been presented in an erosion map of

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)

Sound Propagation Around Off-Shore Wind Turbines. Long-Range Parabolic Equation Calculations for Baltic Sea Conditions

Energy Technology Data Exchange (ETDEWEB)

Johansson, Lisa

2003-07-01

Low-frequency, long-range sound propagation over a sea surface has been calculated using a wide-angel Cranck-Nicholson Parabolic Equation method. The model is developed to investigate noise from off-shore wind turbines. The calculations are made using normal meteorological conditions of the Baltic Sea. Special consideration has been made to a wind phenomenon called low level jet with strong winds on rather low altitude. The effects of water waves on sound propagation have been incorporated in the ground boundary condition using a boss model. This way of including roughness in sound propagation models is valid for water wave heights that are small compared to the wave length of the sound. Nevertheless, since only low frequency sound is considered, waves up to the mean wave height of the Baltic Sea can be included in this manner. The calculation model has been tested against benchmark cases and agrees well with measurements. The calculations show that channelling of sound occurs at downwind conditions and that the sound propagation tends towards cylindrical spreading. The effects of the water waves are found to be fairly small.

Simulation of simultaneous erosion-redeposition processes on material surfaces used in nuclear fusion reactors

International Nuclear Information System (INIS)

Fuentes, Nestor O.; Gavarini, Hebe O.

1999-01-01

Simultaneous erosion and redeposition of sputtered plasma-facing material has been studied using a 3-D computational model. The equations that govern the processes are reduced to a set of nonlinear particle-diffusion equations in which different particle interactions may be taken into account in the corresponding source terms. The effects of a magnetic field with arbitrary direction and of electrostatic potential are also included. The model is based on a combined diffusion limited aggregation and deaggregation code. Hydrogen and deuterium plasmas have been used to simulate erosion-redeposition of low-Z materials such as C, Be and B in the range of sample temperatures where chemical erosion is suppressed and the net erosion yield is due to physical sputtering only. The dependence of net erosion yield on surface temperature, plasma-particles densities and temperatures, and magnetic field intensity and direction is investigated. Computational results emphasize the importance of a magnetic field with appropriate direction and intensity in order to reduce the sputtering effects on surfaces exposed to plasma interactions. (author)

Temporal and spatial variations of rainfall erosivity in Southern Taiwan

Science.gov (United States)

Lee, Ming-Hsi; Lin, Huan-Hsuan; Chu, Chun-Kuang

2014-05-01

Soil erosion models are essential in developing effective soil and water resource conservation strategies. Soil erosion is generally evaluated using the Universal Soil Loss Equation (USLE) with an appropriate regional scale description. Among factors in the USLE model, the rainfall erosivity index (R) provides one of the clearest indications of the effects of climate change. Accurate estimation of rainfall erosivity requires continuous rainfall data; however, such data rarely demonstrate good spatial and temporal coverage. The data set consisted of 9240 storm events for the period 1993 to 2011, monitored by 27 rainfall stations of the Central Weather Bureau (CWB) in southern Taiwan, was used to analyze the temporal-spatial variations of rainfall erosivity. The spatial distribution map was plotted based on rainfall erosivity by the Kriging interpolation method. Results indicated that rainfall erosivity is mainly concentrated in rainy season from June to November typically contributed 90% of the yearly R factor. The temporal variations of monthly rainfall erosivity during June to November and annual rainfall erosivity have increasing trend from 1993 to 2011. There is an increasing trend from southwest to northeast in spatial distribution of rainfall erosivity in southern Taiwan. The results further indicated that there is a higher relationship between elevation and rainfall erosivity. The method developed in this study may also be useful for sediment disasters on Climate Change.

New perspectives on the soil erosion-soil quality relationship

International Nuclear Information System (INIS)

Pennock, D.J.

1998-01-01

The redistribution of soil has a profound impact on its quality (defined as its ability to function within its ecosystem and within adjacent ecosystems) and ultimately on its productivity for crop growth. The application of 137 Cs-redistribution techniques to the study of erosion has yielded major new insights into the soil erosion-soil quality relationship. In highly mechanized agricultural systems, tillage erosion can be the dominant cause of soil redistribution; in other agroecosystems, wind and water erosion dominate. Each causal factor results in characteristic landscape-scale patterns of redistribution. In landscapes dominated by tillage redistribution, highest losses occur in shoulder positions (those with convex downslope curvatures); in water-erosion-dominated landscapes, highest losses occur where slope gradient and length are at a maximum. Major impacts occur through the loss of organically-enriched surface material and through the incorporation of possibly yield-limiting subsoils into the rooting zone of the soil column. The potential impact of surface soil losses and concomitant subsoil incorporation on productivity may be assessed by examining the pedological nature of the affected soils and their position in the landscape. The development of sound conservation policies requires that the soil erosion-quality relationship be rigorously examined in the full range of pedogenic environments, and future applications of the 137 Cs technique hold considerable promise for providing this comprehensive global database. (author)

Soil physical properties affecting soil erosion in tropical soils

International Nuclear Information System (INIS)

Lobo Lujan, D.

2004-01-01

The total vegetated land area of the earth is about 11,500 hectare. Of this, about 12% is in South America. Of this, about 14% is degraded area. Water erosion, chemical degradation, wind erosion, and physical degradation have been reported as main types of degradation. In South America water erosion is a major process for soil degradation. Nevertheless, water erosion can be a consequence of degradation of the soil structure, especially the functional attributes of soil pores to transmit and retain water, and to facilitate root growth. Climate, soil and topographic characteristics determine runoff and erosion potential from agricultural lands. The main factors causing soil erosion can be divided into three groups: Energy factors: rainfall erosivity, runoff volume, wind strength, relief, slope angle, slope length; Protection factors: population density, plant cover, amenity value (pressure for use) and land management; and resistance factors: soil erodibility, infiltration capacity and soil management. The degree of soil erosion in a particular climatic zone, with particular soils, land use and socioeconomic conditions, will always result from a combination of the above mentioned factors. It is not easy to isolate a single factor. However, the soil physical properties that determine the soil erosion process, because the deterioration of soil physical properties is manifested through interrelated problems of surface sealing, crusting, soil compaction, poor drainage, impeded root growth, excessive runoff and accelerated erosion. When an unprotected soil surface is exposed to the direct impact of raindrops it can produce different responses: Production of smaller aggregates, dispersed particles, particles in suspension and translocation and deposition of particles. When this has occurred, the material is reorganized at the location into a surface seal. Aggregate breakdown under rainfall depends on soil strength and a certain threshold kinetic energy is needed to start

Protection of uranium tailings impoundments against overland erosion

International Nuclear Information System (INIS)

Walters, W.H.; Skaggs, R.L.

1986-01-01

This study investigates the problems involved in designing protection methods to prevent erosion of a uranium tailings impoundment cover from rainfall and runoff (overland flow) processes. The study addresses the side slopes and top surface as separate elements. The side slopes are more subject to gully erosion and require absolute protection such as that provided by rock riprap. The flatter top surface needs much less protection (vegetation/rock combinations) but some estimate of erosion rates are needed to compare alternatives. A literature review indicated that, currently, procedures are not available for the design of rock riprap to prevent gully erosion. Therefore, rock protection on the side slope will have to be based upon engineering judgment determined by the particular site conditions. The Manning-kinetic equations (velocity and depth of runoff) were investigated as a possible aid to the design of gully erosion protection. Guidelines are suggested for the use of rock riprap to prevent gully erosion. Three mathematical models were used to compute erosion rates for the top surface of a hypothetical tailings impoundment. The results recommend that one or possibly both of the regression models could be used to evaluate preliminary protection designs for the top surface. A physical process simulation model should be used for the final design. 30 refs., 13 figs., 16 tabs

Finite element method for one-dimensional rill erosion simulation on a curved slope

Directory of Open Access Journals (Sweden)

Lijuan Yan

2015-03-01

Full Text Available Rill erosion models are important to hillslope soil erosion prediction and to land use planning. The development of rill erosion models and their use has become increasingly of great concern. The purpose of this research was to develop mathematic models with computer simulation procedures to simulate and predict rill erosion. The finite element method is known as an efficient tool in many other applications than in rill soil erosion. In this study, the hydrodynamic and sediment continuity model equations for a rill erosion system were solved by the Galerkin finite element method and Visual C++ procedures. The simulated results are compared with the data for spatially and temporally measured processes for rill erosion under different conditions. The results indicate that the one-dimensional linear finite element method produced excellent predictions of rill erosion processes. Therefore, this study supplies a tool for further development of a dynamic soil erosion prediction model.

Erosion Testing of Coatings for V-22 Aircraft Applications

Directory of Open Access Journals (Sweden)

G. Y. Richardson

2003-01-01

Full Text Available High-velocity (183 m/sec sand erosion tests in a wind tunnel were conducted to evaluate developmental coatings from three separate companies under funding by the Navy's phase I small business innovative research program. The purpose of the coatings was to address a particular problem the V-22 tilt-rotor aircraft (Osprey was having with regard to ingestion of sand particles by a titanium impeller that was associated with the aircraft's environmental control system. The three coatings that were deposited on titanium substrates and erosion-tested included (1 SixCy/DLC multilayers deposited by chemical vapor deposition (CVD; (2 WC/TaC/TiC processed by electrospark deposition; and (3 polymer ceramic mixtures applied by means of an aqueous synthesis. The erosion test results are presented; they provided the basis for assessing the suitability of some of these coatings for the intended application.

Rate and cost of soil erosion in Monkayo, Compostela Valley Province Philippines

Directory of Open Access Journals (Sweden)

Sunshine G. Paulin

2016-01-01

Full Text Available Soil erosion is a major agricultural and environmental problem in the Philippines that is primarily caused by rainfall under upland, subsistence rainfed farming. The study sought to compare the degree of erosion as influenced by different upland tillage systems using soil erosion plots and MUSLE model, and estimate the cost of soil erosion in Monkayo, Compostela Valley. The erosion plots were laid on a 31.45 percent slope with a seasonal rainfall intensity of 2,314 mm. Corn (Zea mays L. planted through conventional tillage generated a mean soil loss of 2.64 t/ha/cropping, which is higher than the reduced tillage with a mean of 1.20 t/ha/cropping. The weighted on-site soil loss was 12 percent lower than the obtained soil erosion using the modified Universal Soil Loss Equation that is 2.97 t/ha. The study developed equations to estimate soil loss (t/ha per seasonal rainfall on three tillage systems using linear regression analysis which are: (1 E= -0.0031+0.0003R, (2 E= -0.0406+0.0011R, and (3 E=0.2249+0.0034R in corn grown on undisturbed land with natural vegetation, corn grown on bare soil through dibble method and corn planted through conventional planting system, respectively. On-site cost of erosion ranged from Php 1,473.42/ha/cropping to Php 1,938.81/ha/cropping. The amount of soil eroded can be attributed to the higher erositivity of rains, higher erodibility of the soil surface, and the poor soil cover.

Modeling wind adjustment factor and midflame wind speed for Rothermel's surface fire spread model

Science.gov (United States)

Patricia L. Andrews

2012-01-01

Rothermel's surface fire spread model was developed to use a value for the wind speed that affects surface fire, called midflame wind speed. Models have been developed to adjust 20-ft wind speed to midflame wind speed for sheltered and unsheltered surface fuel. In this report, Wind Adjustment Factor (WAF) model equations are given, and the BehavePlus fire modeling...

Rainfall erosivity factor estimation in Republic of Moldova

Science.gov (United States)

Castraveš, Tudor; Kuhn, Nikolaus

2017-04-01

Rainfall erosivity represents a measure of the erosive force of rainfall. Typically, it is expressed as variable such as the R factor in the Universal Soil Loss Equation (USLE) (Wischmeier and Smith, 1965, 1978) or its derivates. The rainfall erosivity index for a rainfall event (EI30) is calculated from the total kinetic energy and maximum 30 minutes intensity of individual events. However, these data are often unavailable for wide regions and countries. Usually, there are three issues regarding precipitation data: low temporal resolution, low spatial density and limited access to the data. This is especially true for some of postsoviet countries from Eastern Europe, such as Republic of Moldova, where soil erosion is a real and persistent problem (Summer, 2003) and where soils represents the main natural resource of the country. Consequently, researching and managing soil erosion is particularly important. The purpose of this study is to develop a model based on commonly available rainfall data, such as event, daily or monthly amounts, to calculate rainfall erosivity for the territory of Republic of Moldova. Rainfall data collected during 1994-2015 period at 15 meteorological stations in the Republic of Moldova, with 10 minutes temporal resolution, were used to develop and calibrate a model to generate an erosivity map of Moldova. References 1. Summer, W., (2003). Soil erosion in the Republic of Moldova — the importance of institutional arrangements. Erosion Prediction in Ungauged Basins: Integrating Methods and Techniques (Proceedings of symposium HS01 held during IUGG2003 at Sapporo. July 2003). IAHS Publ. no. 279. 2. Wischmeier, W.H., and Smith, D.D. (1965). Predicting rainfall-erosion losses from cropland east of the Rocky Mountains. Agr. Handbook No. 282, U.S. Dept. Agr., Washington, DC 3. Wischmeier, W.H., and Smith, D.D. (1978). Predicting rainfall erosion losses. Agr. handbook No. 537, U.S. Dept. of Agr., Science and Education Administration.

Application Of GIS Software For Erosion Control In The Watershed Scale

Directory of Open Access Journals (Sweden)

C. Setyawan

2017-01-01

Full Text Available Land degradation in form of soil erosion due to uncontrolled farming is occurred in many watersheds of Indonesia particularly in Java Island. Soil erosion is decreasing watershed function as a rainwater harvesting area. Good conservation practices need to be applied to prevent more degradation. This study aims to investigate the effectiveness of land conservation practice for erosion control through land use modeling in the watershed scale. The modeling was applied in the Sempor watershed Indonesia. Three scenarios of land use were used for modeling. Soil erosion measurement and land use modeling were performed by using Universal Soil Loss Equation USLE method and Geographic Information System GIS software ArcGIS 10.1. Land use modeling was conducted by increasing permanent vegetation coverage from existing condition 4 to 10 20 and 30. The result showed that the modeling can reduce heavy class erosion about 15-37 of total area. GIS provides a good tool for erosion control modeling in the watershed scale.

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...

Dynamic modeling and simulation of wind turbines

International Nuclear Information System (INIS)

Ghafari Seadat, M.H.; Kheradmand Keysami, M.; Lari, H.R.

2002-01-01

Using wind energy for generating electricity in wind turbines is a good way for using renewable energies. It can also help to protect the environment. The main objective of this paper is dynamic modeling by energy method and simulation of a wind turbine aided by computer. In this paper, the equations of motion are extracted for simulating the system of wind turbine and then the behavior of the system become obvious by solving the equations. The turbine is considered with three blade rotor in wind direction, induced generator that is connected to the network and constant revolution for simulation of wind turbine. Every part of the wind turbine should be simulated for simulation of wind turbine. The main parts are blades, gearbox, shafts and generator

The Rangeland Hydrology and Erosion Model: A dynamic approach for predicting soil loss on rangelands

Science.gov (United States)

In this study we present the improved Rangeland Hydrology and Erosion Model (RHEM V2.3), a process-based erosion prediction tool specific for rangeland application. The article provides the mathematical formulation of the model and parameter estimation equations. Model performance is assessed agains...

Coupling of an aeroacoustic model and a parabolic equation code for long range wind turbine noise propagation

Science.gov (United States)

Cotté, B.

2018-05-01

This study proposes to couple a source model based on Amiet's theory and a parabolic equation code in order to model wind turbine noise emission and propagation in an inhomogeneous atmosphere. Two broadband noise generation mechanisms are considered, namely trailing edge noise and turbulent inflow noise. The effects of wind shear and atmospheric turbulence are taken into account using the Monin-Obukhov similarity theory. The coupling approach, based on the backpropagation method to preserve the directivity of the aeroacoustic sources, is validated by comparison with an analytical solution for the propagation over a finite impedance ground in a homogeneous atmosphere. The influence of refraction effects is then analyzed for different directions of propagation. The spectrum modification related to the ground effect and the presence of a shadow zone for upwind receivers are emphasized. The validity of the point source approximation that is often used in wind turbine noise propagation models is finally assessed. This approximation exaggerates the interference dips in the spectra, and is not able to correctly predict the amplitude modulation.

Cometary X-rays : solar wind charge exchange in cometary atmospheres

NARCIS (Netherlands)

Bodewits, Dennis

2007-01-01

The interaction of the solar wind with the planets and the interstellar medium is of key importance for the evolution of our solar system. The interaction with Earth's atmosphere is best known for the northern light. In case of Mars, the interaction with the solar wind might have lead to the erosion

Wind profile modelling using WAsP and "tall" wind measurements

DEFF Research Database (Denmark)

Floors, Rogier Ralph; Kelly, Mark C.; Troen, Ib

2015-01-01

extrapolations (the wind profile) this is done using the Weibull distribution and the geostrophic drag law. Wind lidar measurements obtained during the ’Tall wind’ campaign at three different sites are used to evaluate the assumptions and equations that are used in the WAsP vertical extrapolation strategy...

Evaluating the new soil erosion map of Hungary

Science.gov (United States)

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

2017-04-01

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

Wind erodibility of soils from North Darfur State

International Nuclear Information System (INIS)

Medani, G. H.; Mustafa, M. A.

2003-01-01

Wind erodibility of soils (WE) is a prime factor for the prediction, assessment and mapping of wind erosion. Hence, this study was undertaken to generate WE data and pertinent relationships for North Darfur State. Surface soil samples (0-3 cm) were collected from forty farms scattered all over the state. Non-erodible soil particles (NEP) (>0.84 mm in diameter), WE and various relevant physical and chemical soil properties were determined. Regression analysis showed that NEP significantly (p 2 =0.825), clay (r 2 =0.754), silt (r 2 =0.737) and clay/ (silt + sand) ratio (r 2 =0.663), and decreased with increase in sand (r 2 =0.761), (silt+sand) / clay ratio (r 2 =0.766) and (silt+sand) / (clay+organic matter) ratio (r 2 =0.811). The four basic soil properties and their ratios gave the reverse effects on WE with slightly lower coefficients of determinations. Although organic matter is a slightly better predictor of both NEP and WE than (Si+S)/ (C+OM) ratio, the latter is preferred because it integrates in addition to OM resilient soil properties. A multiple regression equation with a relatively high coefficient of determination (R 2 =0.830) may also be used for predicting NEP from knowledge of the four prime soil properties. These properties accounted for only 62% of the variation of WE, thus it is not recommended for prediction purposes. The determined wind erodibility groups correlated very well with those established else where.(Author)

Transport of biologically important nutrients by wind in an eroding cold desert

Science.gov (United States)

Sankey, Joel B.; Germino, Matthew J.; Benner, Shawn G.; Glenn, Nancy F.; Hoover, Amber N.

2012-01-01

Wind erosion following fire is an important landscape process that can result in the redistribution of ecologically important soil resources. In this study we evaluated the potential for a fire patch in a desert shrubland to serve as a source of biologically important nutrients to the adjacent, downwind, unburned ecosystem. We analyzed nutrient concentrations (P, K, Ca, Mg, Cu, Fe, Mn, Al) in wind-transported sediments, and soils from burned and adjacent unburned surfaces, collected during the first to second growing seasons after a wildfire that burned in 2007 in Idaho, USA in sagebrush steppe; a type of cold desert shrubland. We also evaluated the timing of potential wind erosion events and weather conditions that might have contributed to nutrient availability in downwind shrubland. Findings indicated that post-fire wind erosion resulted in an important, but transient, addition of nutrients on the downwind shrubland. Aeolian sediments from the burned area were enriched relative to both the up- and down-wind soil and indicated the potential for a fertilization effect through the deposition of the nutrient-enriched sediment during the first, but not second, summer after wildfire. Weather conditions that could have produced nutrient transport events might have provided increased soil moisture necessary to make nutrients accessible for plants in the desert environment. Wind transport of nutrients following fire is likely important in the sagebrush steppe as it could contribute to pulses of resource availability that might, for example, affect plant species differently depending on their phenology, and nutrient- and water-use requirements.

Use of the Universal Soil-Loss Equation to determine water erosion with the semi-circular bund water-harvesting technique in the Syrian Steppe

Directory of Open Access Journals (Sweden)

Hamdan Al Mahmoud

2014-05-01

Full Text Available This research was conducted through the rain season 2009 -2010, in Mehasseh Research Center at (Al Qaryatein, The area is characterized by a hot and dry climate in summer and cold in winter with an annual average rainfall of 114 mm. Three slopes (8%, 6%, 4% were used in semicircular bunds water -harvesting techniques with bunds parallel to the contours lines at flow distance of 18, 12 and 6 m. The bunds were planted with Atriplex Halimus seedlings. Graded metal rulers were planted inside the bunds to determine soil loss and sedimentation associated with the surface runoff, and metallic tanks were placed at the end of the flow paths to determine agricultural soil loss from water runoff. A rain intensity gauge was placed near the experiment site to determine the rainfall intensity that produced runoff. The treatments were done in three replications. The amount of soil erosion (in tons per hectare per year increased with increasing of the slope, the highest recorded value was 38.66 at slope of 8% and the lowest 0.05 at 4% slope. The amount of soil erosion also increased with increasing of water run distance, which was 38.66 T.ha-1.yr-1 at 18 m and 0.05 T.ha-1.yr-1 at 6 m . Bunds with different diameter of water harvesting reduced soil erosion by about 65% at slope of 8%, 55% at 6%, and 46% at 4%. The input parameters of Universal soil-loss equation were found to be suitable for determining soil erosion in this arid and semi-arid region. DOI: http://dx.doi.org/10.3126/ije.v3i2.10499 International Journal of the Environment Vol.3(2 2014: 1-11

Assessing soil erosion using USLE model and MODIS data in the Guangdong, China

Science.gov (United States)

Gao, Feng; Wang, Yunpeng; Yang, Jingxue

2017-07-01

In this study, soil erosion in the Guangdong, China during 2012 was quantitatively assessed using Universal Soil Loss Equation (USLE). The parameters of the model were calculated using GIS and MODIS data. The spatial distribution of the average annual soil loss on grid basis was mapped. The estimated average annual soil erosion in Guangdong in 2012 is about 2294.47t/ (km2.a). Four high sensitive area of soil erosion in Guangdong in 2012 was found. The key factors of these four high sensitive areas of soil erosion were significantly contributed to the land cover types, rainfall and Economic development and human activities.

Soil Erosion Study through Simulation: An Educational Tool.

Science.gov (United States)

Huber, Thomas P.; Falkenmayer, Karen

1987-01-01

Discusses the need for education about soil erosion and advocates the use of the Universal Soil Loss Equation (USLE) to show the impacts of human and natural action on the land. Describes the use of a computer simulated version of the USLE in several environmental and farming situations. (TW)

Nonlinear internal gravity waves and their interaction with the mean wind

International Nuclear Information System (INIS)

Grimshaw, R.

1975-01-01

The interaction of a wave packet of internal gravity waves with the mean wind is investigated, for the case when there is a region of wind shear and hence a critical level. The principal equations are the Doppler-shifted dispersion relation, the equation for conservation of wave action and the mean momentum equation, in which the mean wind is accelerated by a 'radiation stress' tensor, due to the waves. These equations are integrated numerically to study the behaviour of a wave packet approaching a critical level, where the horizontal phase speed matches the mean wind. The results demonstrate the exchange of energy from the waves to the mean wind in the vicinity of the critical level. The interaction between the waves and the mean wind is also studied in the absence of any initial wind shear. (author)

Water erosion risk prediction in eucalyptus plantations

Directory of Open Access Journals (Sweden)

Mayesse Aparecida da Silva

2014-04-01

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

Soil erosion in Iran: Issues and solutions

Science.gov (United States)

Hamidreza Sadeghi, Seyed; Cerdà, Artemi

2015-04-01

Iran currently faces many soil erosion-related problems (see citations below). These issues are resulted from some inherent characteristic and anthropogenic triggering forces. Nowadays, the latter plays more important rule to accelerate the erosion with further emphasis on soil erosion-prone arid and semi arid regions of the country. This contribution attempts to identify and describe the existing main reasons behind accelerated soil erosion in Iran. Appropriate solutions viz. structural and non-structural approaches will be then advised to combat or minimise the problems. Iran can be used as a pilot research site to understand the soil erosion processes in semiarid, arid and mountainous terrain and our research will review the scientific literature and will give an insight of the soil erosion rates in the main factors of the soil erosion in Iran. Key words: Anthropogenic Erosion, Land Degradation; Sediment Management; Sediment Problems Acknowledgements The research projects GL2008-02879/BTE, LEDDRA 243857 and PREVENTING AND REMEDIATING DEGRADATION OF SOILS IN EUROPE THROUGH LAND CARE (RECARE)FP7-ENV-2013- supported this research. References Aghili Nategh, N., Hemmat, A., & Sadeghi, M. (2014). Assessing confined and semi-confined compression curves of highly calcareous remolded soil amended with farmyard manure. Journal of Terramechanics, 53, 75-82. Arekhi, S., Bolourani, A. D., Shabani, A., Fathizad, H., Ahamdy-Asbchin, S. 2012. Mapping Soil Erosion and Sediment Yield Susceptibility using RUSLE, Remote Sensing and GIS (Case study: Cham Gardalan Watershed, Iran). Advances in Environmental Biology, 6(1), 109-124. Arekhi, S., Shabani, A., Rostamizad, G. 2012. Application of the modified universal soil loss equation (MUSLE) in prediction of sediment yield (Case study: Kengir Watershed, Iran). Arabian Journal of Geosciences, 5(6), 1259-1267.Sadeghi, S. H., Moosavi, V., Karami, A., Behnia, N. 2012. Soil erosion assessment and prioritization of affecting factors at plot

Aeroservoelasticity of Wind Turbines

DEFF Research Database (Denmark)

Kallesøe, Bjarne Skovmose

2007-01-01

This thesis deals with the fundamental aeroelastic interaction between structural motion, Pitch action and control for a wind turbine blade. As wind turbines become larger, the interaction between pitch action, blade motion, aerodynamic forces, and control become even more important to understand......, and furthermore linear and therefore suitable for control design. The development of the primary aeroelastic blade model is divided into four steps: 1) Nonlinear partial differential equations (PDEs) of structural blade motion are derived together with equations of pitch action and rotor speed; the individual...... to a 2D blade section model, and it can be used instead of this in many applications, giving a transparent connection to a real wind turbine blade. In this work the aeroelastic blade model is used to analyze interaction between pitch action, blade motion and wind speed variations. Furthermore the model...

Assessing Rainfall Erosivity with Artificial Neural Networks for the Ribeira Valley, Brazil

Directory of Open Access Journals (Sweden)

Reginald B. Silva

2010-01-01

Full Text Available Soil loss is one of the main causes of pauperization and alteration of agricultural soil properties. Various empirical models (e.g., USLE are used to predict soil losses from climate variables which in general have to be derived from spatial interpolation of point measurements. Alternatively, Artificial Neural Networks may be used as a powerful option to obtain site-specific climate data from independent factors. This study aimed to develop an artificial neural network to estimate rainfall erosivity in the Ribeira Valley and Coastal region of the State of São Paulo. In the development of the Artificial Neural Networks the input variables were latitude, longitude, and annual rainfall and a mathematical equation of the activation function for use in the study area as the output variable. It was found among other things that the Artificial Neural Networks can be used in the interpolation of rainfall erosivity values for the Ribeira Valley and Coastal region of the State of São Paulo to a satisfactory degree of precision in the estimation of erosion. The equation performance has been demonstrated by comparison with the mathematical equation of the activation function adjusted to the specific conditions of the study area.

Wind uplift of radioactive dust from the ground

International Nuclear Information System (INIS)

Makhon'ko, K.P.

1992-01-01

Near nuclear power plants the recontamination of the atmosphere near the ground becomes dangerous, if a radioactive zone has formed at the site. Wind can easily carry toxic dust from the polluted territory of neighboring industrial enterprises. Moreover, wind erosion of the soil during the summer or transport of radioactive snow by a snowstorm during the winter can displace the boundaries of the contaminated radioactive zone. In Russia the investigation of wind pickup of radioactive dust from the ground began after a radiation accident occurred at a storage facility in the Southern Urals in 1957, as a result of which a contaminated zone formed in the area. Since the direct mechanism of detachment of dust particles from the ground is not important in studying the results of the raising of radioactive dust into the atmosphere by wind, the authors do not distinguish between wind pickup and wind erosion, and the entire process wind pickup of radioactivity from the ground. After the radiation accident at the Chernobyl nuclear power plant a new generation of investigators began to study wind pickup of radioactive dust from the ground, and the process under consideration was sometimes referred to as wind uplift. The intensity of the process of wind pickup of radioactive dust from the ground is characterized by the wind pickup coefficient α, which is the coefficient of proportionality between the upward flux Q of radioactivity from the ground and the density A of radioactive contamination of the ground: α = Q/A. Physically, the coefficient α is the upward flux of the impurity from the ground with unit contamination density, i.e., the intensity of dust contamination or the fraction of radioactivity picked up by the wind from the ground per unit time. The greatest difficulty in determining α experimentally under dusty conditions is measuring correctly the upward radioactivity flux Q. The author discusses three methods for determining this quantity

CFD study of fluid flow changes with erosion

Science.gov (United States)

López, Alejandro; Stickland, Matthew T.; Dempster, William M.

2018-06-01

For the first time, a three dimensional mesh deformation algorithm is used to assess fluid flow changes with erosion. The validation case chosen is the Jet Impingement Test, which was thoroughly analysed in previous works by Hattori et al. (Kenichi Sugiyama and Harada, 2008), Gnanavelu et al. in (Gnanavelu et al., 2009, 2011), Lopez et al. in (Lopez et al., 2015) and Mackenzie et al. in (Mackenzie et al., 2015). Nguyen et al. (2014) showed the formation of a new stagnation area when the wear scar is deep enough by performing a three-dimensional scan of the wear scar after 30 min of jet impingement test. However, in the work developed here, this stagnation area was obtained solely by computational means. The procedure consisted of applying an erosion model in order to obtain a deformed geometry, which, due to the changes in the flow pattern lead to the formation of a new stagnation area. The results as well as the wear scar were compared to the results by Nguyen et al. (2014) showing the same trend. OpenFOAM® was the software chosen for the implementation of the deforming mesh algorithm as well as remeshing of the computational domain after deformation. Different techniques for mesh deformation and approaches to erosion modelling are discussed and a new methodology for erosion calculation including mesh deformation is developed. This new approach is independent of the erosion modelling approach, being applicable to both Eulerian and Lagrangian based equations for erosion calculation. Its different applications such as performance decay in machinery subjected to erosion as well as modelling of natural erosion processes are discussed here.

Prediction of long-term erosion from landfill covers in the southwest

International Nuclear Information System (INIS)

Anderson, C.E.; Stormont, J.C.

1997-01-01

Erosion is a primary stressor of landfill covers, especially for climates with high intensity storms and low native plant density. Rills and gullies formed by discrete events can damage barrier layers and induce failure. Geomorphologic, empirical and physical modeling procedures are available to provide estimates of surface erosion, but numerical modeling requires accurate representation of the severe rainfall events that generate erosion. The National Weather Service precipitation frequency data and estimates of 5, 10, 15, 30 and 60-minute intensity can be statistically combined in a numerical model to obtain long-term erosion estimates. Physically based numerical models using the KINEROS and AHYMO programs have been utilized to predict the erosion from a southwestern landfill or waste containment site with 0.03, 0.05 and 0.08 meter per meter surface slopes. Results of AHYMO modeling were within 15 percent of average annual values computed with the empirical Universal Soil Loss Equation. However, the estimation of rill and gully formation that primarily degrades cover systems requires quantifying single events. For Southwestern conditions, a single 10-year storm can produce erosion quantifies equal to three times the average annual erosion and a 100-year storm can produce five times the average annual erosion

Stellar wind theory

International Nuclear Information System (INIS)

Summers, D.

1980-01-01

The theory of stellar winds as given by the equations of classical fluid dynamics is considered. The equations of momentum and energy describing a steady, spherically symmetric, heat-conducting, viscous stellar wind are cast in a dimensionless form which involves a thermal conduction parameter E and a viscosity parameter γ. An asymptotic analysis is carried out, for fixed γ, in the cases E→O and E→infinity (corresponding to small and large thermal conductivity, respectively), and it is found that it is possible to construct critical solutions for the wind velocity and temperature over the entire flow. The E→O solution represents a wind which emanates from the star at low, subsonic speeds, accelerates through a sonic point, and then approaches a constant asymptotic speed, with its temperature varying as r/sup -4/3/ at large distances r from the star; the E→infinity solution represents a wind which, after reaching an approximately constant speed, with temperature varying as r/sup -2/7/, decelerates through a diffuse shock and approaches a finite pressure at infinity. A categorization is made of all critical stellar wind solutions for given values of γ and E, and actual numerical examples are given. Numerical solutions are obtained by integrating upstream 'from infinity' from initial values of the flow parameters given by appropriate asymptotic expansions. The role of viscosity in stellar wind theory is discussed, viscous and inviscid stellar wind solutions are compared, and it is suggested that with certain limitations, the theory presented may be useful in analyzing winds from solar-type stars

Rainfall erosivity in subtropical catchments and implications for erosion and particle-bound contaminant transfer: a case-study of the Fukushima region

Science.gov (United States)

Laceby, J. P.; Chartin, C.; Evrard, O.; Onda, Y.; Garcia-Sanchez, L.; Cerdan, O.

2015-07-01

The Fukushima Dai-ichi nuclear power plant (FDNPP) accident in March 2011 resulted in a significant fallout of radiocesium over the Fukushima region. After reaching the soil surface, radiocesium is almost irreversibly bound to fine soil particles. Thereafter, rainfall and snow melt run-off events transfer particle-bound radiocesium downstream. Erosion models, such as the Universal Soil Loss Equation (USLE), depict a proportional relationship between rainfall and soil erosion. As radiocesium is tightly bound to fine soil and sediment particles, characterizing the rainfall regime of the fallout-impacted region is fundamental to modelling and predicting radiocesium migration. Accordingly, monthly and annual rainfall data from ~ 60 meteorological stations within a 100 km radius of the FDNPP were analysed. Monthly rainfall erosivity maps were developed for the Fukushima coastal catchments illustrating the spatial heterogeneity of rainfall erosivity in the region. The mean average rainfall in the Fukushima region was 1387 mm yr-1 (σ 230) with the mean rainfall erosivity being 2785 MJ mm ha-1 yr-1 (σ 1359). The results indicate that the majority of rainfall (60 %) and rainfall erosivity (86 %) occurs between June and October. During the year, rainfall erosivity evolves positively from northwest to southeast in the eastern part of the prefecture, whereas a positive gradient from north to south occurs in July and August, the most erosive months of the year. During the typhoon season, the coastal plain and eastern mountainous areas of the Fukushima prefecture, including a large part of the contamination plume, are most impacted by erosive events. Understanding these rainfall patterns, particularly their spatial and temporal variation, is fundamental to managing soil and particle-bound radiocesium transfers in the Fukushima region. Moreover, understanding the impact of typhoons is important for managing sediment transfers in subtropical regions impacted by cyclonic activity.

Wind-US Users Guide Version 4.0

Science.gov (United States)

Yoder, Dennis A.

2016-01-01

Wind-US is a computational platform which may be used to numerically solve various sets of equations governing physical phenomena. Currently, the code supports the solution of the Euler and Navier-Stokes equations of fluid mechanics, along with supporting equation sets governing turbulent and chemically reacting flows. Wind-US is a product of the NPARC Alliance, a partnership between the NASA Glenn Research Center (GRC) and the Arnold Engineering Development Complex (AEDC) dedicated to the establishment of a national, applications-oriented flow simulation capability. The Boeing Company has also been closely associated with the Alliance since its inception, and represents the interests of the NPARC User's Association. The "Wind-US User's Guide" describes the operation and use of Wind-US, including: a basic tutorial; the physical and numerical models that are used; the boundary conditions; monitoring convergence; the files that are read and/or written; parallel execution; and a complete list of input keywords and test options. For current information about Wind-US and the NPARC Alliance, please see the Wind-US home page at http://www.grc.nasa.gov/WWW/winddocs/ and the NPARC Alliance home page at http://www.grc.nasa.gov/WWW/wind/.

Fabry-Perot interferometer measurements of neutral winds and F2 layer variations at the magnetic equator

Directory of Open Access Journals (Sweden)

P. Vila

1998-06-01

Full Text Available This letter presents some night-time observations of neutral wind variations at F2 layer levels near the dip equator, measured by the Fabry-Perot interferometer set up in 1994 at Korhogo (Ivory Coast, geographic latitude 9.25°N, longitude 355°E, dip latitude –2.5°. Our instrument uses the 630 nm (O1D line to determine radial Doppler velocities of the oxygen atoms between 200 and 400 km altitude. First results for November 1994 to March 1995 reveal persistent eastward flows, and frequent intervals of southward winds of larger than 50 ms–1 velocity. Compared with the simultaneous ionospheric patterns deduced from the three West African equatorial ionosondes at Korhogo, Ouagadougou (Burkina-Faso, dip latitude +1.5° and Dakar (Sénégal, dip latitude +5°, they illustrate various impacts of the thermospheric winds on F2 layer density: (1 on the mesoscale evolution (a few 103 km and a few 100 minutes scales and (2 on local fluctuations (hundreds of km and tens of minutes characteristic times. We report on these fluctuations and discuss the opportunity to improve the time-resolution of the Fabry-Perot interferometer at Korhogo.Key words. Ionosphere (Equatorial ionosphere; Ionosphere-atmosphere interaction · Meteorology and Atmospheric Dynamics (General circulation

Optimization and Reliability Problems in Structural Design of Wind Turbines

DEFF Research Database (Denmark)

Sørensen, John Dalsgaard

2007-01-01

are discussed. Limit state equations are presented for fatigue limit states and for ultimate limit states with extreme wind load, and illustrated by bending failure. Illustrative examples are presented, and as a part of the results optimal reliability levels are obtained which corresponds to an annual...... reliability index equal to 3. An example with fatigue failure indicates that the reliability level is almost the same for single wind turbines and for wind turbines in wind farms if the wake effects are modeled equivalently in the design equation and the limit state equation....

Estimates of soil erosion using cesium-137 tracer models.

Science.gov (United States)

Saç, M M; Uğur, A; Yener, G; Ozden, B

2008-01-01

The soil erosion was studied by 137Cs technique in Yatagan basin in Western Turkey, where there exist intensive agricultural activities. This region is subject to serious soil loss problems and yet there is not any erosion data towards soil management and control guidelines. During the soil survey studies, the soil profiles were examined carefully to select the reference points. The soil samples were collected from the slope facets in three different study areas (Kirtas, Peynirli and Kayisalan Hills). Three different models were applied for erosion rate calculations in undisturbed and cultivated sites. The profile distribution model (PDM) was used for undisturbed soils, while proportional model (PM) and simplified mass balance model (SMBM) were used for cultivated soils. The mean annual erosion rates found using PDM in undisturbed soils were 15 t ha(-1) year(-1) at the Peynirli Hill and 27 t ha(-1) year(-1) at the Kirtas Hill. With the PM and SMBM in cultivated soils at Kayişalan, the mean annual erosion rates were obtained to be 65 and 116 t ha(-1) year(-1), respectively. The results of 137Cs technique were compared with the results of the Universal Soil Loss Equation (USLE).

Estimation of local rainfall erosivity using artificial neural network

Directory of Open Access Journals (Sweden)

Paulo Tarso Sanches Oliveira

2011-08-01

Full Text Available The information retrieval of local values of rainfall erosivity is essential for soil loss estimation with the Universal Soil Loss Equation (USLE, and thus is very useful in soil and water conservation planning. In this manner, the objective of this study was to develop an Artificial Neural Network (ANN with the capacity of estimating, with satisfactory accuracy, the rainfall erosivity in any location of the Mato Grosso do Sul state. We used data from rain erosivity, latitude, longitude, altitude of pluviometric and pluviographic stations located in the state to train and test an ANN. After training with various network configurations, we selected the best performance and higher coefficient of determination calculated on the basis of data erosivity of the sample test and the values estimated by ANN. In evaluating the results, the confidence and the agreement indices were used in addition to the coefficient of determination. It was found that it is possible to estimate the rainfall erosivity for any location in the state of Mato Grosso do Sul, in a reliable way, using only data of geographical coordinates and altitude.

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

Science.gov (United States)

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

2015-04-01

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

Evaluation of compost blankets for erosion control from disturbed lands.

Science.gov (United States)

Bhattarai, Rabin; Kalita, Prasanta K; Yatsu, Shotaro; Howard, Heidi R; Svendsen, Niels G

2011-03-01

Soil erosion due to water and wind results in the loss of valuable top soil and causes land degradation and environmental quality problems. Site specific best management practices (BMP) are needed to curb erosion and sediment control and in turn, increase productivity of lands and sustain environmental quality. The aim of this study was to investigate the effectiveness of three different types of biodegradable erosion control blankets- fine compost, mulch, and 50-50 mixture of compost and mulch, for soil erosion control under field and laboratory-scale experiments. Quantitative analysis was conducted by comparing the sediment load in the runoff collected from sloped and tilled plots in the field and in the laboratory with the erosion control blankets. The field plots had an average slope of 3.5% and experiments were conducted under natural rainfall conditions, while the laboratory experiments were conducted at 4, 8 and 16% slopes under simulated rainfall conditions. Results obtained from the field experiments indicated that the 50-50 mixture of compost and mulch provides the best erosion control measures as compared to using either the compost or the mulch blanket alone. Laboratory results under simulated rains indicated that both mulch cover and the 50-50 mixture of mulch and compost cover provided better erosion control measures compared to using the compost alone. Although these results indicate that the 50-50 mixtures and the mulch in laboratory experiments are the best measures among the three erosion control blankets, all three types of blankets provide very effective erosion control measures from bare-soil surface. Results of this study can be used in controlling erosion and sediment from disturbed lands with compost mulch application. Testing different mixture ratios and types of mulch and composts, and their efficiencies in retaining various soil nutrients may provide more quantitative data for developing erosion control plans. Copyright © 2010 Elsevier

RECONSTRUCTING THE SOLAR WIND FROM ITS EARLY HISTORY TO CURRENT EPOCH

Energy Technology Data Exchange (ETDEWEB)

Airapetian, Vladimir S.; Usmanov, Arcadi V., E-mail: vladimir.airapetian@nasa.gov, E-mail: avusmanov@gmail.com [NASA Goddard Space Flight Center, Greenbelt, MD (United States)

2016-02-01

Stellar winds from active solar-type stars can play a crucial role in removal of stellar angular momentum and erosion of planetary atmospheres. However, major wind properties except for mass-loss rates cannot be directly derived from observations. We employed a three-dimensional magnetohydrodynamic Alfvén wave driven solar wind model, ALF3D, to reconstruct the solar wind parameters including the mass-loss rate, terminal velocity, and wind temperature at 0.7, 2, and 4.65 Gyr. Our model treats the wind thermal electrons, protons, and pickup protons as separate fluids and incorporates turbulence transport, eddy viscosity, turbulent resistivity, and turbulent heating to properly describe proton and electron temperatures of the solar wind. To study the evolution of the solar wind, we specified three input model parameters, the plasma density, Alfvén wave amplitude, and the strength of the dipole magnetic field at the wind base for each of three solar wind evolution models that are consistent with observational constrains. Our model results show that the velocity of the paleo solar wind was twice as fast, ∼50 times denser and 2 times hotter at 1 AU in the Sun's early history at 0.7 Gyr. The theoretical calculations of mass-loss rate appear to be in agreement with the empirically derived values for stars of various ages. These results can provide realistic constraints for wind dynamic pressures on magnetospheres of (exo)planets around the young Sun and other active stars, which is crucial in realistic assessment of the Joule heating of their ionospheres and corresponding effects of atmospheric erosion.

RECONSTRUCTING THE SOLAR WIND FROM ITS EARLY HISTORY TO CURRENT EPOCH

International Nuclear Information System (INIS)

Airapetian, Vladimir S.; Usmanov, Arcadi V.

2016-01-01

Stellar winds from active solar-type stars can play a crucial role in removal of stellar angular momentum and erosion of planetary atmospheres. However, major wind properties except for mass-loss rates cannot be directly derived from observations. We employed a three-dimensional magnetohydrodynamic Alfvén wave driven solar wind model, ALF3D, to reconstruct the solar wind parameters including the mass-loss rate, terminal velocity, and wind temperature at 0.7, 2, and 4.65 Gyr. Our model treats the wind thermal electrons, protons, and pickup protons as separate fluids and incorporates turbulence transport, eddy viscosity, turbulent resistivity, and turbulent heating to properly describe proton and electron temperatures of the solar wind. To study the evolution of the solar wind, we specified three input model parameters, the plasma density, Alfvén wave amplitude, and the strength of the dipole magnetic field at the wind base for each of three solar wind evolution models that are consistent with observational constrains. Our model results show that the velocity of the paleo solar wind was twice as fast, ∼50 times denser and 2 times hotter at 1 AU in the Sun's early history at 0.7 Gyr. The theoretical calculations of mass-loss rate appear to be in agreement with the empirically derived values for stars of various ages. These results can provide realistic constraints for wind dynamic pressures on magnetospheres of (exo)planets around the young Sun and other active stars, which is crucial in realistic assessment of the Joule heating of their ionospheres and corresponding effects of atmospheric erosion

A large source of dust missing in Particulate Matter emission inventories? Wind erosion of post-fire landscapes

Directory of Open Access Journals (Sweden)

N.S. Wagenbrenner

2017-02-01

Full Text Available Wind erosion of soils burned by wildfire contributes substantial particulate matter (PM in the form of dust to the atmosphere, but the magnitude of this dust source is largely unknown. It is important to accurately quantify dust emissions because they can impact human health, degrade visibility, exacerbate dust-on-snow issues (including snowmelt timing, snow chemistry, and avalanche danger, and affect ecological and biogeochemical cycles, precipitation regimes, and the Earth’s radiation budget. We used a novel modeling approach in which local-scale winds were used to drive a high-resolution dust emission model parameterized for burned soils to provide a first estimate of post-fire PM emissions. The dust emission model was parameterized with dust flux measurements from a 2010 fire scar. Here we present a case study to demonstrate the ability of the modeling framework to capture the onset and dynamics of a post-fire dust event and then use the modeling framework to estimate PM emissions from burn scars left by wildfires in U.S. western sagebrush landscapes during 2012. Modeled emissions from 1.2 million ha of burned soil totaled 32.1 Tg (11.7–352 Tg of dust as PM10 and 12.8 Tg (4.68–141 Tg as PM2.5. Despite the relatively large uncertainties in these estimates and a number of underlying assumptions, these first estimates of annual post-fire dust emissions suggest that post-fire PM emissions could substantially increase current annual PM estimates in the U.S. National Emissions Inventory during high fire activity years. Given the potential for post-fire scars to be a large source of PM, further on-site PM flux measurements are needed to improve emission parameterizations and constrain these first estimates.

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

Science.gov (United States)

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

Thermal erosion of a permafrost coastline: Improving process-based models using time-lapse photography

Science.gov (United States)

Wobus, C.; Anderson, R.; Overeem, I.; Matell, N.; Clow, G.; Urban, F.

2011-01-01

Coastal erosion rates locally exceeding 30 m y-1 have been documented along Alaska's Beaufort Sea coastline, and a number of studies suggest that these erosion rates have accelerated as a result of climate change. However, a lack of direct observational evidence has limited our progress in quantifying the specific processes that connect climate change to coastal erosion rates in the Arctic. In particular, while longer ice-free periods are likely to lead to both warmer surface waters and longer fetch, the relative roles of thermal and mechanical (wave) erosion in driving coastal retreat have not been comprehensively quantified. We focus on a permafrost coastline in the northern National Petroleum Reserve-Alaska (NPR-A), where coastal erosion rates have averaged 10-15 m y-1 over two years of direct monitoring. We take advantage of these extraordinary rates of coastal erosion to observe and quantify coastal erosion directly via time-lapse photography in combination with meteorological observations. Our observations indicate that the erosion of these bluffs is largely thermally driven, but that surface winds play a crucial role in exposing the frozen bluffs to the radiatively warmed seawater that drives melting of interstitial ice. To first order, erosion in this setting can be modeled using formulations developed to describe iceberg deterioration in the open ocean. These simple models provide a conceptual framework for evaluating how climate-induced changes in thermal and wave energy might influence future erosion rates in this setting.

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)

Wind-US Users Guide Version 3.0

Science.gov (United States)

Yoder, Dennis A.

2016-01-01

Wind-US is a computational platform which may be used to numerically solve various sets of equations governing physical phenomena. Currently, the code supports the solution of the Euler and Navier-Stokes equations of fluid mechanics, along with supporting equation sets governing turbulent and chemically reacting flows. Wind-US is a product of the NPARC Alliance, a partnership between the NASA Glenn Research Center (GRC) and the Arnold Engineering Development Complex (AEDC) dedicated to the establishment of a national, applications-oriented flow simulation capability. The Boeing Company has also been closely associated with the Alliance since its inception, and represents the interests of the NPARC User's Association. The "Wind-US User's Guide" describes the operation and use of Wind-US, including: a basic tutorial; the physical and numerical models that are used; the boundary conditions; monitoring convergence; the files that are read and/or written; parallel execution; and a complete list of input keywords and test options. For current information about Wind-US and the NPARC Alliance, please see the Wind-US home page at http://www.grc.nasa.gov/WWW/winddocs/ and the NPARC Alliance home page at http://www.grc.nasa.gov/WWW/wind/. This manual describes the operation and use of Wind-US, a computational platform which may be used to numerically solve various sets of equations governing physical phenomena. Wind-US represents a merger of the capabilities of four CFD codes - NASTD (a structured grid flow solver developed at McDonnell Douglas, now part of Boeing), NPARC (the original NPARC Alliance structured grid flow solver), NXAIR (an AEDC structured grid code used primarily for store separation analysis), and ICAT (an unstructured grid flow solver developed at the Rockwell Science Center and Boeing).

Shelter Index and a simple wind speed parameter to characterize vegetation control of sand transport threshold and Flu

Science.gov (United States)

Gillies, J. A.; Nield, J. M.; Nickling, W. G.; Furtak-Cole, E.

2014-12-01

Wind erosion and dust emissions occur in many dryland environments from a range of surfaces with different types and amounts of vegetation. Understanding how vegetation modulates these processes remains a research challenge. Here we present results from a study that examines the relationship between an index of shelter (SI=distance from a point to the nearest upwind vegetation/vegetation height) and particle threshold expressed as the ratio of wind speed measured at 0.45 times the mean plant height divided by the wind speed at 17 m when saltation commences, and saltation flux. The results are used to evaluate SI as a parameter to characterize the influence of vegetation on local winds and sediment transport conditions. Wind speed, wind direction, saltation activity and point saltation flux were measured at 35 locations in defined test areas (~13,000 m2) in two vegetation communities: mature streets of mesquite covered nebkhas and incipient nebkhas dominated by low mesquite plants. Measurement positions represent the most open areas, and hence those places most susceptible to wind erosion among the vegetation elements. Shelter index was calculated for each measurement position for each 10° wind direction bin using digital elevation models for each site acquired using terrestrial laser scanning. SI can show the susceptibility to wind erosion at different time scales, i.e., event, seasonal, or annual, but in a supply-limited system it can fail to define actual flux amounts due to a lack of knowledge of the distribution of sediment across the surface of interest with respect to the patterns of SI.

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 High Temperature Particle Erosion Resistance of Vanadium-Boride Coating

International Nuclear Information System (INIS)

Lee, E. Y.; Kim, J. H.; Jeong, S. I.; Lee, S. H.; Eum, G. W.

2015-01-01

The components in ultra super critical (USC) steam turbine, which is under development for high efficient power generation, are encountering harsher solid particle erosion by iron oxide scales than ones in the existing steam turbines. Therefore, the currently used boride coating will not be able to hold effective protection from particle erosion in USC system and should be replaced by new particle erosion resistant coatings. One of the best protective coatings developed for USC steam turbine parts was found to be vanadium-boride (V-boride) coating which has a hardness of about 3000 HV, much higher than that of boride, 1600∼2000 HV. In order to evaluate particle erosion resistance of the various coatings such as V-boride, boride and Cr-carbide coatings at high temperature, particle erosion test equipment were designed and manufactured. In addition, erosion particle velocity was simulated using FLUENT software based on semi-implicity method for pressure linked equations revised (SIMPLER). Based on experimental results of this work, the vanadium-boride coating was found to be superior to others and to be a candidate coating to replace the boride coating

Evaluation of High Temperature Particle Erosion Resistance of Vanadium-Boride Coating

Energy Technology Data Exchange (ETDEWEB)

Lee, E. Y.; Kim, J. H.; Jeong, S. I. [Andong National University, Andong (Korea, Republic of); Lee, S. H.; Eum, G. W. [Corporate R and D Institute Doosan Heavy Industries and Construction Co., Changwon (Korea, Republic of)

2015-04-15

The components in ultra super critical (USC) steam turbine, which is under development for high efficient power generation, are encountering harsher solid particle erosion by iron oxide scales than ones in the existing steam turbines. Therefore, the currently used boride coating will not be able to hold effective protection from particle erosion in USC system and should be replaced by new particle erosion resistant coatings. One of the best protective coatings developed for USC steam turbine parts was found to be vanadium-boride (V-boride) coating which has a hardness of about 3000 HV, much higher than that of boride, 1600∼2000 HV. In order to evaluate particle erosion resistance of the various coatings such as V-boride, boride and Cr-carbide coatings at high temperature, particle erosion test equipment were designed and manufactured. In addition, erosion particle velocity was simulated using FLUENT software based on semi-implicity method for pressure linked equations revised (SIMPLER). Based on experimental results of this work, the vanadium-boride coating was found to be superior to others and to be a candidate coating to replace the boride coating.

Computation of rainfall erosivity from daily precipitation amounts.

Science.gov (United States)

Beguería, Santiago; Serrano-Notivoli, Roberto; Tomas-Burguera, Miquel

2018-10-01

Rainfall erosivity is an important parameter in many erosion models, and the EI30 defined by the Universal Soil Loss Equation is one of the best known erosivity indices. One issue with this and other erosivity indices is that they require continuous breakpoint, or high frequency time interval, precipitation data. These data are rare, in comparison to more common medium-frequency data, such as daily precipitation data commonly recorded by many national and regional weather services. Devising methods for computing estimates of rainfall erosivity from daily precipitation data that are comparable to those obtained by using high-frequency data is, therefore, highly desired. Here we present a method for producing such estimates, based on optimal regression tools such as the Gamma Generalised Linear Model and universal kriging. Unlike other methods, this approach produces unbiased and very close to observed EI30, especially when these are aggregated at the annual level. We illustrate the method with a case study comprising more than 1500 high-frequency precipitation records across Spain. Although the original records have a short span (the mean length is around 10 years), computation of spatially-distributed upscaling parameters offers the possibility to compute high-resolution climatologies of the EI30 index based on currently available, long-span, daily precipitation databases. Copyright © 2018 Elsevier B.V. All rights reserved.

Post-wildfire soil erosion in the Mediterranean: Review and future research directions

Science.gov (United States)

Shakesby, R. A.

2011-04-01

Wildfires increased dramatically in frequency and extent in the European Mediterranean region from the 1960s, aided by a general warming and drying trend, but driven primarily by socio-economic changes, including rural depopulation, land abandonment and afforestation with flammable species. Published research into post-wildfire hydrology and soil erosion, beginning during the 1980s in Spain, has been followed by studies in other European Mediterranean countries together with Israel and has now attained a sufficiently large critical mass to warrant a major review. Although variations in climate, vegetation, soil, topography and fire severity cause differences in Mediterranean post-wildfire erosion, the long history of human landscape impact up to the present day is responsible for some its distinctive characteristics. This paper highlights these characteristics in reviewing wildfire impacts on hydrology, soil properties and soil erosion by water. The 'mosaic' nature of many Mediterranean landscapes (e.g. an intricate land-use pattern, abandoned terraces and tracks interrupting slopes) may explain sometimes conflicting post-fire hydrological and erosional responses at different sites and spatial scales. First-year post-wildfire soil losses at point- (average, 45-56 t ha - 1 ) and plot-scales (many Aspect is important, with more erosion reported for south- than north-facing slopes, which is attributed to greater fire frequency, slower vegetation recovery on the former and with soil characteristics more prone to erosion (e.g. lower aggregate stability). Post-fire wind erosion is a potentially important but largely neglected process. Gauging the degradational significance of wildfires has relied on comparison with unburnt land, but the focus for comparison should be switched to other agents of soil disturbance and/or currently poorly understood soil renewal rates. Human impact on land use and vegetation may alter expected effects (increased fire activity and post

Detection of soil erosion within pinyon-juniper woodlands using Thematic Mapper (TM) data

Science.gov (United States)

Price, Kevin P.

1993-01-01

Multispectral measurements collected by Landsat Thematic Mapper (TM) were correlated with field measurements, direct soil loss estimates, and Universal Soil Loss Equation (USLE) estimates to determine the sensitivity of TM data to varying degrees of soil erosion in pinyon-juniper woodland in central Utah. TM data were also evaluated as a predictor of the USLE Crop Management C factor for pinyon-juniper woodlands. TM spectral data were consistently better predictors of soil erosion factors than any combination of field factors. TM data were more sensitive to vegetation variations than the USLE C factor. USLE estimates showed low annual rates of erosion which varied little among the study sites. Direct measurements of rate of soil loss using the SEDIMENT (Soil Erosion DIrect measureMENT) technique, indicated high and varying rates of soil loss among the sites since tree establishment. Erosion estimates from the USLE and SEDIMENT methods suggest that erosion rates have been severe in the past, but because significant amounts of soil have already been eroded, and the surface is now armored by rock debris, present erosion rates are lower. Indicators of accelerated erosion were still present on all sites, however, suggesting that the USLE underestimated erosion within the study area.

Hydro-abrasive erosion on coated Pelton runners: Partial calibration of the IEC model based on measurements in HPP Fieschertal

Science.gov (United States)

Felix, D.; Abgottspon, A.; Albayrak, I.; Boes, R. M.

2016-11-01

At medium- and high-head hydropower plants (HPPs) on sediment-laden rivers, hydro-abrasive erosion on hydraulic turbines is a major economic issue. For optimization of such HPPs, there is an interest in equations to predict erosion depths. Such a semi-empirical equation suitable for engineering practice is proposed in the relevant guideline of the International Electrotechnical Commission (IEC 62364). However, for Pelton turbines no numerical values of the model's calibration parameters have been available yet. In the scope of a research project at the high-head HPP Fieschertal, Switzerland, the particle load and the erosion on the buckets of two hard-coated 32 MW-Pelton runners have been measured since 2012. Based on three years of field data, the numerical values of a group of calibration parameters of the IEC erosion model were determined for five application cases: (i) reduction of splitter height, (ii) increase of splitter width and (iii) increase of cut-out depth due to erosion of mainly base material, as well as erosion of coating on (iv) the splitter crests and (v) inside the buckets. Further laboratory and field investigations are recommended to quantify the effects of individual parameters as well as to improve, generalize and validate erosion models for uncoated and coated Pelton turbines.

Process-based coastal erosion modeling for Drew Point (North Slope, Alaska)

Science.gov (United States)

Ravens, Thomas M.; Jones, Benjamin M.; Zhang, Jinlin; Arp, Christopher D.; Schmutz, Joel A.

2012-01-01

A predictive, coastal erosion/shoreline change model has been developed for a small coastal segment near Drew Point, Beaufort Sea, Alaska. This coastal setting has experienced a dramatic increase in erosion since the early 2000’s. The bluffs at this site are 3-4 m tall and consist of ice-wedge bounded blocks of fine-grained sediments cemented by ice-rich permafrost and capped with a thin organic layer. The bluffs are typically fronted by a narrow (∼ 5  m wide) beach or none at all. During a storm surge, the sea contacts the base of the bluff and a niche is formed through thermal and mechanical erosion. The niche grows both vertically and laterally and eventually undermines the bluff, leading to block failure or collapse. The fallen block is then eroded both thermally and mechanically by waves and currents, which must occur before a new niche forming episode may begin. The erosion model explicitly accounts for and integrates a number of these processes including: (1) storm surge generation resulting from wind and atmospheric forcing, (2) erosional niche growth resulting from wave-induced turbulent heat transfer and sediment transport (using the Kobayashi niche erosion model), and (3) thermal and mechanical erosion of the fallen block. The model was calibrated with historic shoreline change data for one time period (1979-2002), and validated with a later time period (2002-2007).

Thermodynamic performance assessment of wind energy systems: An application

International Nuclear Information System (INIS)

Redha, Adel Mohammed; Dincer, Ibrahim; Gadalla, Mohamed

2011-01-01

In this paper, the performance of wind energy system is assessed thermodynamically, from resource and technology perspectives. The thermodynamic characteristics of wind through energy and exergy analyses are considered and both energetic and exergetic efficiencies are studied. Wind speed is affected by air temperature and pressure and has a subsequent effect on wind turbine performance based on wind reference temperature and Bernoulli's equation. VESTAS V52 wind turbine is selected for (Sharjah/UAE). Energy and exergy efficiency equations for wind energy systems are further developed for practical applications. The results show that there are noticeable differences between energy and exergy efficiencies and that exergetic efficiency reflects the right/actual performance. Finally, exergy analysis has been proven to be the right tool used in design, simulation, and performance evaluation of all renewable energy systems. -- Highlights: → In this research the performance of wind energy system is assessed thermodynamically, from resource and technology perspectives. → Energy and exergy equations for wind energy systems are further developed for practical applications. → Thermodynamic characteristics of wind turbine systems through energetic and exergetic efficiencies are evaluated from January till March 2010. → Exergy efficiency describes the system irreversibility and the minimum irreversibility exists when the wind speed reaches 11 m/s. → The power production during March was about 17% higher than the month of February and 66% higher than January.

The impacts of grazing land management on the wind erodibility of the Mulga Lands of western Queensland, Australia

Science.gov (United States)

An estimated 100 Mt of dust is eroded by wind from the Australian land surface each year. Wind erosion may be widespread across the arid and semi-arid rangelands, with impacts on soil nutrients, carbon and ecosystem services, human health, and climate. The susceptibility of landscapes to wind erosio...

Modelling desertification risk in the north-west of Jordan using geospatial and remote sensing techniques

Directory of Open Access Journals (Sweden)

Jawad T. Al-Bakri

2016-03-01

Full Text Available Remote sensing, climate, and ground data were used within a geographic information system (GIS to map desertification risk in the north-west of Jordan. The approach was based on modelling wind and water erosion and incorporating the results with a map representing the severity of drought. Water erosion was modelled by the universal soil loss equation, while wind erosion was modelled by a dust emission model. The extent of drought was mapped using the evapotranspiration water stress index (EWSI which incorporated actual and potential evapotranspiration. Output maps were assessed within GIS in terms of spatial patterns and the degree of correlation with soil surficial properties. Results showed that both topography and soil explained 75% of the variation in water erosion, while soil explained 25% of the variation in wind erosion, which was mainly controlled by natural factors of topography and wind. Analysis of the EWSI map showed that drought risk was dominating most of the rainfed areas. The combined effects of soil erosion and drought were reflected on the desertification risk map. The adoption of these geospatial and remote sensing techniques is, therefore, recommended to map desertification risk in Jordan and in similar arid environments.

Study of wind forces on low-rise hip-roof building

African Journals Online (AJOL)

DR OKE

to predict the wind loads and the flow patterns around the hip-roof building. .... various wind angle attack on the roof using CFD simulation. .... SIMPLE algorithm substitutes the flux correction equations into the discrete continuity equation to ...

[Responses of soil fauna to environment degeneration in the process of wind erosion desertification of Hulunbeir steppe].

Science.gov (United States)

Lü, Shi-Hai; Lu, Xin-Shi; Gao, Ji-Xi

2007-09-01

To reveal the relationships between soil fauna and soil environmental factors in the process of steppe desertification, field survey combined with laboratory analysis was made to study the community structure, population density and biodiversity of soil fauna, and their relationships with the changes of soil organic matter, hydrolysable nitrogen, available phosphorus and moisture contents and soil pH at different stages of desertification of Hulunbeir steppe. The soil faunal specimens collected belonged to 4 phyla, 6 classes and 12 orders. Nematoda was the only dominant group of medium- and small-sized soil fauna, occupying 94.3% of the total, while Coleoptera and Hemiptera were the dominant groups of large-sized soil fauna, with the amount of 79.7%. The group amount, population density, diversity, and evenness of soil fauna had an obvious decreasing trend with the aggravation of steppe desertification. At serious stage of desertification, soil fauna vanished completely. The population density of soil fauna in 0-20 cm soil layer had significant linear correlations with soil nutrients and moisture contents, soil pH, and litter mass, indicating that soil fauna had stronger sensibility to the changes of soil environmental factors in the process of wind erosion desertification of Hulunbeir steppe.

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

Directory of Open Access Journals (Sweden)

Vinícius Augusto de Oliveira

2014-06-01

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

Rill erosion of mudstone slope-a case study of southern Taiwan

Science.gov (United States)

Yang, Ci-Jian; Lin, Jiun-chuan; Cheng, Yuan-Chang

2014-05-01

Soil erosion has been studied by many scientists for decades (Zingg, 1940; Meyer & Wischmeier, 1969; Foster, 1982; Luk, 1988) and many soil erosion prediction equations have already been developed, such as USLE, RUSLE. In spite of WEEP is based on hydrological physical model, all of the above models are restricted to predict concentrate flow. On the other hand, rill erosion is not understood completely. The amounts of rill erosion are always underestimated. Rill Erosion correlate closely to gradient (Cerda & Garcia-Fayos, 1997; Fox & Bryan, 1999; Fu,et al., 2011; Clarke & Rendell, 2006), slope length (Gabriel, 1999; Yair, 2004), particle distribution (Gabriel, 1999), proportion of clay (Luk,1977; Bryan2000), rainfall intensity (Römkens et al. 2001), and land use (Dotterweich, 2008). However, the effect of micromorphology of mud rock surface, such as mud-cracks, could be studied in more details. This research aims to simulate rill development by hydraulic flume to observe the morphological change caused by rill/erosion process. Mudstone specimens sampled from the mudstone area of Long-Chi, southern Taiwan. The results show that: (1) The erosion pattern of mudstone slope can be divided into four steps: (a) inter-rill erosion, ( b) rill erosion, (c) rill development, (d) slope failure. (2) Slopes with mud-cracks caused 125% soil loss than smooth slopes. (3) Mud-cracks affect spatial distribution of rill development (4) The sediment concentration decreased sharply in the beginning of experiments, however increased due to rill development. This paper demonstrated such a rill development. 1: Department of Geography, National Taiwan University. E-mail:maxpossibilism0929@gmail.com

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

Science.gov (United States)

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

2013-08-01

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

Aeroservoelasticity of wind turbines

Energy Technology Data Exchange (ETDEWEB)

Skovmose Kallesoee, B.

2007-12-14

This thesis deals with the fundamental aeroelastic interaction between structural motion, Pitch action and control for a wind turbine blade. As wind turbines become larger, the interaction between pitch action, blade motion, aerodynamic forces, and control become even more important to understand and address. The main contribution of this thesis is the development of an aeroelastic blade model which on the one hand includes the important effects of steady state blade deformation, gravity and pitch action, and on the other it is transparent, suitable for analytical analysis and parameter studies, and furthermore linear and therefore suitable for control design. The development of the primary aeroelastic blade model is divided into four steps: 1) Nonlinear partial differential equations (PDEs) of structural blade motion are derived together with equations of pitch action and rotor speed; the individual terms in these equations are discussed and given physical interpretations; 2) Steady state blade deformation and induced velocities are computed by combining the PDEs with a steady state aerodynamic model; 3) Aeroelastic modes of motion are computed by combining the linearized PDEs with a linear unsteady aerodynamic model; this model is used to analyze how blade deformation effects the modes of motion; and 4) the linear aeroelastic blade model is derived by a modal expansion of the linearized PDEs combined with a linear unsteady aerodynamic model. The aeroelastic blade model has many similarities to a 2D blade section model, and it can be used instead of this in many applications, giving a transparent connection to a real wind turbine blade. In this work the aeroelastic blade model is used to analyze interaction between pitch action, blade motion and wind speed variations. Furthermore the model is used to develop a state estimator for estimating the wind speed and wind shear, and to suggest a load reducing controller. The state estimator estimates the wind shear very

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

Directory of Open Access Journals (Sweden)

Jarbou A. Bahrawi

2016-01-01

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

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

Directory of Open Access Journals (Sweden)

Pasini G.

2009-07-01

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

2010 Cost of Wind Energy Review

Energy Technology Data Exchange (ETDEWEB)

Tegen, S. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Hand, M. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Maples, B. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Lantz, E. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Schwabe, P. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Smith, A. [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2012-04-01

This document provides a detailed description of NREL's levelized cost of wind energy equation, assumptions, and results in 2010, including historical cost trends and future projections for land-based and offshore utility-scale wind.

2010 Cost of Wind Energy Review

Energy Technology Data Exchange (ETDEWEB)

Tegen, S.; Hand, M.; Maples, B.; Lantz, E.; Schwabe, P.; Smith, A.

2012-04-01

This document provides a detailed description of NREL's levelized cost of wind energy equation, assumptions and results in 2010, including historical cost trends and future projections for land-based and offshore utility-scale wind.

Modelling the Stem Curve of a Palm in a Strong Wind

DEFF Research Database (Denmark)

Philipsen, Claus; Markvorsen, Steen; Kliem, Wolfhard

1996-01-01

Nonlinear differential equations governing the stem curve of a wind-loaded palm are derived and solved numerically.......Nonlinear differential equations governing the stem curve of a wind-loaded palm are derived and solved numerically....

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

Science.gov (United States)

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.

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

Science.gov (United States)

Molla, Tegegne; Sisheber, Biniam

2017-01-01

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

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

Science.gov (United States)

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

2018-05-01

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

Water erosion of dystrophic Red Latosols (Oxisols

Directory of Open Access Journals (Sweden)

Joaquim Ernesto Bernardes Ayer

2015-06-01

Full Text Available In their natural state, Latosols (Oxisols present great stability and resistance to erosion, being the most abundant and used soils for farming and cattle raising activities in southern Minas Gerais State, Brazil. However, along the last one hundred years, they have been submitted to intensive cultivation and managements which favor water erosion. This study aimed to estimate the water erosion rates of dystrophic Red Latosols from the Revised Universal Soil Loss Equation, compared with the soil loss tolerance limits, and assess the impact on water erosion of the managements more common in the region, by alternative conservation management simulation. Soil loss tolerance limits ranged from 8.94 Mg ha-1 year-1 to 9.99 Mg ha-1 year-1, with the study area presenting a susceptibility of soil loss of 23.86 Mg year-1, with an average rate of 8.40 Mg ha-1 year-1, corresponding to 34.80 % of the area with values above the soil loss tolerance limit. The biggest annual losses occur in areas with use and management of eucalyptus grown downhill (30.67 Mg ha-1 year-1 and pasture under continuous occupancy (11.10 Mg ha-1 year-1. However, when the average loss per type of use is considered, the areas more susceptible to water erosion are those with potato and eucalyptus crops, grown downhill, and those in bare soil. Nevertheless, in the simulated conservation management scenario, the average losses would be drastically reduced (8.40 Mg ha-1 year-1 to 2.84 Mg ha-1 year-1 and only 4.00 % of the area with soil loss would remain above the tolerance limits.

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...

Application of the system of water erosion control measures in growths of special cultivations

Directory of Open Access Journals (Sweden)

Vítězslav Hálek

2004-01-01

Full Text Available The aim of the study is to select an optimal variant of the system of water erosion control measures. The water erosion issue was observed and evaluated in 15 blocks of special cultivations-vineyards and orchards. These blocks are situated in the managed area of the join-stock company PATRIA Kobylí. At first the average long-term loss of soil with the influence of water erosion is calculated. The universal Wischmeier-Smith equation is used for this purpose. If the calculated loss of soil exceeds the permissible value, the erosion control measures have to be suggested. The optimal variant has been selected on the bases of the evaluation of several kinds of measures in each block. This variant follows first of all the erosion control efficiency, but also demands on production as well as slope accessibility for mechanization, expensiveness and some negative sides of suggested measures. The suggested system of water erosion control measures contributes to increasing of soil fertility and production ability with the respect to landscape management and environmental protection.

Development of Erosive Burning Models for CFD Predictions of Solid Rocket Motor Internal Environments

Science.gov (United States)

Wang, Qun-Zhen

2003-01-01

Four erosive burning models, equations (11) to (14). are developed in this work by using a power law relationship to correlate (1) the erosive burning ratio and the local velocity gradient at propellant surfaces; (2) the erosive burning ratio and the velocity gradient divided by centerline velocity; (3) the erosive burning difference and the local velocity gradient at propellant surfaces; and (4) the erosive burning difference and the velocity gradient divided by centerline velocity. These models depend on the local velocity gradient at the propellant surface (or the velocity gradient divided by centerline velocity) only and, unlike other empirical models, are independent of the motor size. It was argued that, since the erosive burning is a local phenomenon occurring near the surface of the solid propellant, the erosive burning ratio should be independent of the bore diameter if it is correlated with some local flow parameters such as the velocity gradient at the propellant surface. This seems to be true considering the good results obtained by applying these models, which are developed from the small size 5 inch CP tandem motor testing, to CFD simulations of much bigger motors.

Linking rapid erosion of the Mekong River delta to human activities.

Science.gov (United States)

Anthony, Edward J; Brunier, Guillaume; Besset, Manon; Goichot, Marc; Dussouillez, Philippe; Nguyen, Van Lap

2015-10-08

As international concern for the survival of deltas grows, the Mekong River delta, the world's third largest delta, densely populated, considered as Southeast Asia's most important food basket, and rich in biodiversity at the world scale, is also increasingly affected by human activities and exposed to subsidence and coastal erosion. Several dams have been constructed upstream of the delta and many more are now planned. We quantify from high-resolution SPOT 5 satellite images large-scale shoreline erosion and land loss between 2003 and 2012 that now affect over 50% of the once strongly advancing >600 km-long delta shoreline. Erosion, with no identified change in the river's discharge and in wave and wind conditions over this recent period, is consistent with: (1) a reported significant decrease in coastal surface suspended sediment from the Mekong that may be linked to dam retention of its sediment, (2) large-scale commercial sand mining in the river and delta channels, and (3) subsidence due to groundwater extraction. Shoreline erosion is already responsible for displacement of coastal populations. It is an additional hazard to the integrity of this Asian mega delta now considered particularly vulnerable to accelerated subsidence and sea-level rise, and will be exacerbated by future hydropower dams.

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

Directory of Open Access Journals (Sweden)

Panos Panagos

2015-04-01

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

Integration of transport concepts for risk assessment of pesticide erosion.

Science.gov (United States)

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

2016-05-01

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

Is Snow Gliding a Major Soil Erosion Agent in Steep Alpine Areas?

International Nuclear Information System (INIS)

Meusburger, K.; Walter, A.; Alewell, C.; Leitinger, G.; Mabit, L.; Mueller, M.H.

2015-01-01

Snow cover is a key hydrological characteristic of mountain areas. Nevertheless, a majority of studies focused on quantifying rates of soil erosion and sediment transport in steep mountain areas has largely neglected the role of snow cover on soil erosion rates (Stanchi et al., 2014). Soil erosion studies have focused almost exclusively on the snow-free periods even though it is well known that wet avalanches can yield enormous erosive forces (Freppaz et al., 2010; Korup and Rixen, 2014). This raises the question whether annual snow cover and particularly the slow movement of snow packages over the soil surface, termed ‘‘snow gliding’’, contribute significantly to the total soil loss in these areas. Three different approaches to estimate soil erosion rates were used to address this question. These include (1) the anthropogenic soil tracer 137 Cs, (2) the Revised Universal Soil Loss Equation (RUSLE), and (3) direct sediment yield measurements of snow glide deposits. The fallout radionuclide 137 Cs integrates total soil loss due to all erosion agents involved, the RUSLE model is suitable to estimate soil loss by water erosion and the sediment yield measurements yield represents a direct estimate of soil removal by snow gliding. Moreover, cumulative snow glide distance was measured for 14 sites and modelled for the surrounding area with the Spatial Snow Glide Model (Leitinger et al., 2008)

Field evaluation of support practice (P-factor) for stone walls to control soil erosion in an arid area (Northern Jordan)

Science.gov (United States)

Gharaibeh, Mamoun; Albalasmeh, Ammar

2017-04-01

Stone walls have been adopted for long time to control water erosion in many Mediterranean countries. In soil erosion equations, the support practice factor (P-factor) for stone walls has not been fully studied or rarely taken into account especially in semi-arid and arid regions. Field studies were conducted to evaluate the efficiency of traditional stone walls and to quantify soil erosion in six sites in north and northeastern Jordan. Initial estimates using the Universal Soil Loss Equation (USLE) showed that rainfall erosion was reduced by 65% in areas where stone walls are present. Annual soil loss ranged from 5 to 15 t yr-1. The mean annual soil loss in the absence of stone walls ranged from 10-60 t ha-1 with an average value of 35 t ha-1. Interpolating the slope of thickness of A horizon provided an average initial estimate of 0.3 for P value.

LiDAR-based 2D Localization and Mapping System using Elliptical Distance Correction Models for UAV Wind Turbine Blade Inspection

DEFF Research Database (Denmark)

Nikolov, Ivan Adriyanov; Madsen, Claus B.

2017-01-01

The wind energy sector faces a constant need for annual inspections of wind turbine blades for damage, erosion and cracks. These inspections are an important part of the wind turbine life cycle and can be very costly and hazardous to specialists. This has led to the use of automated drone inspect...

Shoosing the appropriate size wind turbine

Energy Technology Data Exchange (ETDEWEB)

Lynette, R. [FloWind Corp., San Rafael, CA (United States)

1996-12-31

Within the past several years, wind turbines rated at 400 kW and higher have been introduced into the market, and some manufacturers are developing machines rated at 750 - 1,000+ kW. This raises the question: What is the appropriate size for utility-grade wind turbines today? The answer depends upon the site where the machines will be used and the local conditions. The issues discussed in the paper are: (1) Site-Related (a) Visual, noise, erosion, television interference, interference with aviation (b) Siting efficiency (2) Logistics (a) Adequacy of roads and bridges to accept large vehicles (b) Availability and cost of cranes for erection and maintenance (c) Capability of local repair/overhauls (3) Cost Effectiveness (a) Capital costs (1) Wind Turbine (2) Infrastructure costs (b) Maintenance costs (4) Technical/Financial Risk. 1 fig., 1 tab.

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

Science.gov (United States)

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 Distribution of Annual and Monthly Rainfall Erosivity in the Jaguarí River Basin

Directory of Open Access Journals (Sweden)

Lucas Machado Pontes

2017-11-01

Full Text Available ABSTRACT The Jaguarí River Basin forms the main water supply sources for the São Paulo Metropolitan Region and other cities in the state. Since the kinetic energy of rainfall is the driving force of water erosion, the main cause of land and water degradation, we tested the hypothesis of correlation between the erosive potential of rainfall (erosivity and geographical coordinates and altitude for the purpose of predicting the spatial and temporal distribution of the rainfall erosivity index (EI30 in the basin. An equation was used to estimate the (EI30 in accordance with the average monthly and total annual rainfall at rainfall stations with data available for the study area. In the regression kriging technique, the deterministic part was modeled using multiple linear regression between the dependent variable (EI30 and environmental predictor variables: latitude, longitude, and altitude. From the result of equations and the maps generated, a direct correlation between erosivity and altitude could be observed. Erosivity has a markedly seasonal behavior in accordance with the rainy season from October to March. This season concentrates 86 % of the estimated EI30 values, with monthly maximum values of up to 2,342 MJ mm ha-1 h-1 month-1 between December and January, and minimum of 34 MJ mm ha-1 h-1 month-1 in August. The highest values were found in the Mantiqueira Range region (annual average of up to 12,000 MJ mm ha-1 h-1, a region that should be prioritized in soil and water conservation efforts. From this validation, good precision and accuracy of the model was observed for the long period of the annual average, which is the main factor used in soil loss prediction models.

Detection of soil erosion within pinyon-juniper woodlands using Thematic Mapper (TM) satellite data

Science.gov (United States)

Price, Kevin P.; Ridd, Merrill K.

1991-01-01

The sensitivity of Landsat TM data for detecting soil erosion within pinyon-juniper woodlands, and the potential of the spectral data for assigning the universal soil loss equation (USLE) crop managemnent (C) factor to varying cover types within the woodlands are assessed. Results show greatly accelerated rates of soil erosion on pinyon-juniper sites. Percent cover by pinyon-juniper, total soil-loss, and total nonliving ground cover accounted for nearly 70 percent of the variability in TM channels 2, 3, 4, and 5. TM spectral data were consistently better predictors of soil erosion than the biotic and abiotic field variables. Satellite data were more sensitive to vegetation variation than the USLE C factor, and USLE was found to be a poor predictor of soil loss on pinyon-juniper sites. A new string-to-ground soil erosion prediction technique is introduced.

Dynamics of Line-Driven Winds from Disks in Cataclysmic Variables. I. Solution Topology and Wind Geometry

OpenAIRE

Feldmeier, Achim; Shlosman, Isaac

1999-01-01

We analyze the dynamics of 2-D stationary, line-driven winds from accretion disks in cataclysmic variable stars. The driving force is that of line radiation pressure, in the formalism developed by Castor, Abbott & Klein for O stars. Our main assumption is that wind helical streamlines lie on straight cones. We find that the Euler equation for the disk wind has two eigenvalues, the mass loss rate and the flow tilt angle with the disk. Both are calculated self-consistently. The wind is characte...

An equatorial temperature and wind anomaly (ETWA)

International Nuclear Information System (INIS)

Raghavarao, R.; Wharton, L.E.; Mayr, H.G.; Brace, L.H.; Spencer, N.W.

1991-01-01

Data obtained from the WATS (Wind and Temperature Spectrometer) and LP (Langmuir Probe) experiments on board DE-2 (Dynamic Explorer) during high solar activity show evidence of anomalous latitudinal variations in the zonal winds and temperature at low latitudes. The zonal winds exhibit a broad maximum centered around the dip equator, flanked by minima on either side around 25 degrees; while the temperature exhibits a pronounced bowl-shaped minimum at the dip equator which is flanked by maxima. The two minima in the zonal winds and the corresponding maxima in the temperature are nearly collocated with the crests of the well known Equatorial Ionization Anomaly (EIA). The maximum in the zonal winds and the minimum in the gas temperature are collected with the trough of the EIA. The differences between the maxima and minima in temperature and zonal winds, on many occasions, are observed to exceed 100 K and 100 m/s, respectively. The characteristics of this new phenomenon have eluded present day empirical models of thermospheric temperature and winds. The connection among these variables can be understood from the ion-neutral drag effect on the motions of the neutrals that in turn affect their energy balance

The June 2016 Australian East Coast Low: Importance of Wave Direction for Coastal Erosion Assessment

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Thomas R. Mortlock

2017-02-01

Full Text Available In June 2016, an unusual East Coast Low storm affected some 2000 km of the eastern seaboard of Australia bringing heavy rain, strong winds and powerful wave conditions. While wave heights offshore of Sydney were not exceptional, nearshore wave conditions were such that beaches experienced some of the worst erosion in 40 years. Hydrodynamic modelling of wave and current behaviour as well as contemporaneous sand transport shows the east to north-east storm wave direction to be the major determinant of erosion magnitude. This arises because of reduced energy attenuation across the continental shelf and the focussing of wave energy on coastal sections not equilibrated with such wave exposure under the prevailing south-easterly wave climate. Narrabeen–Collaroy, a well-known erosion hot spot on Sydney’s Northern Beaches, is shown to be particularly vulnerable to storms from this direction because the destructive erosion potential is amplified by the influence of the local embayment geometry. We demonstrate the magnified erosion response that occurs when there is bi-directionality between an extreme wave event and preceding modal conditions and the importance of considering wave direction in extreme value analyses.

Soil erosion assessment of a Himalayan river basin using TRMM data

Science.gov (United States)

Pandey, A.; Mishra, S. K.; Gautam, A. K.; Kumar, D.

2015-04-01

In this study, an attempt has been made to assess the soil erosion of a Himalayan river basin, the Karnali basin, Nepal, using rainfall erosivity (R-factor) derived from satellite-based rainfall estimates (TRMM-3B42 V7). Average annual sediment yield was estimated using the well-known Universal Soil Loss Equation (USLE). The eight-year annual average rainfall erosivity factor (R) for the Karnali River basin was found to be 2620.84 MJ mm ha-1 h-1 year-1. Using intensity-erosivity relationships and eight years of the TRMM daily rainfall dataset (1998-2005), average annual soil erosion was also estimated for Karnali River basin. The minimum and maximum values of the rainfall erosivity factor were 1108.7 and 4868.49 MJ mm ha-1 h-1 year-1, respectively, during the assessment period. The average annual soil loss of the Karnali River basin was found to be 38.17 t ha-1 year-1. Finally, the basin area was categorized according to the following scale of erosion severity classes: Slight (0 to 5 t ha-1 year-1), Moderate (5 to 10 t ha-1 year-1), High (10 to 20 t ha-1 year-1), Very High (20 to 40 t ha-1 year-1), Severe (40 to 80 t ha-1 year-1) and Very Severe (>80 t ha-1 year-1). About 30.86% of the river basin area was found to be in the slight erosion class. The areas covered by the moderate, high, very high, severe and very severe erosion potential zones were 13.09%, 6.36%, 11.09%, 22.02% and 16.64% respectively. The study revealed that approximately 69% of the Karnali River basin needs immediate attention from a soil conservation point of view.

Turbulent wind at the equatorial segment of an operating Darrieus wind turbine blade

Science.gov (United States)

Connell, J. R.; Morris, V. R.

1989-09-01

Six turbulent wind time series, measured at equally spaced equator-height locations on a circle 3 m outside a 34-m Darrieus rotor, are analyzed to approximate the wind fluctuations experienced by the rotor. The flatwise lower root-bending stress of one blade was concurrently recorded. The wind data are analyzed in three ways: wind components that are radial and tangential to the rotation of a blade were rotationally sampled; induction and wake effects of the rotor were estimated from the six Eulerian time series; and turbulence spectra of both the measured wind and the modeled wind from the PNL theory of rotationally sampled turbulence. The wind and the rotor response are related by computing the spectral response function of the flatwise lower root-bending stress. Two bands of resonant response that surround the first and second flatwise modal frequencies shift with the rotor rotation rate.

Reduction of the performance of a noise screen due to screen-induced wind-speed gradients: numerical computations and wind-tunnel experiments

NARCIS (Netherlands)

Salomons, E.M.

1999-01-01

Downwind sound propagation over a noise screen is investigated by numerical computations and scale model experiments in a wind tunnel. For the computations, the parabolic equation method is used, with a range-dependent sound-speed profile based on wind-speed profiles measured in the wind tunnel and

Assessing and monitoring soil erosion and land degradation in Malta

Science.gov (United States)

Symeonakis, Elias; Brearley, James

2017-04-01

The United Nations Convention to Combat Desertification (UNCCD) identifies the Mediterranean as one of the most seriously affected by land degradation and desertification (LDD) regions in the World. LDD is a complex process related with a multitude of biogeographical and socioeconomic parameters and is often assessed using proxies or indicators. One of the most important indicators of LDD is soil erosion. Here, we assess the evolution of soil erosion and LDD in the Mediterranean islands of Malta between 1986 and 2002. Soil erosion is estimated using the Revised Soil Loss Equation (RUSLE). For the assessment of LDD, we employ a modification of the Environmentally Sensitive Area Index (ESAI) methodology with Landsat imagery and ancillary GIS datasets. We incorporate 4 vegetation-related indicators, 3 climate-related, 5 soil-related and 3 socio-economic ones in the final assessment of the evolution of LDD. Results show that there has been an increase in soil erosion rates and in the sensitivity to LDD in the areas of San Pawl il-Bahar and Il-Mizieb most likely due to the transition from agricultural use to Mediterranean shrubs. Also, almost the entire country is flagged as belonging to the 'Fragile' and 'Critical' ESAI classes. It is clear that soil erosion and LDD mitigation measures are necessary, especially in the most critical (i.e. 'C3') areas which occupy 10% of Malta.

Role of grounded ship 'MV River Princess' in triggering erosion: A case study from Candolim Sinquerim Coast, Goa.

Digital Repository Service at National Institute of Oceanography (India)

ManiMurali, R.; Babu, M.T.; Sudhesh, K.; Mascarenhas, A.; Vethamony, P.

are conducive for sand bar formation on the lee side. The intensity of winds and higher significant wave height (Hs) during SW monsoon further deteriorates the shore front which has already become fragile due to severe erosion along beach front...

Grid-cell based assessment of soil erosion potential for identification of critical erosion prone areas using USLE, GIS and remote sensing: A case study in the Kapgari watershed, India

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Gurjeet Singh

2017-09-01

Full Text Available Estimation of soil erosion is of paramount importance due to its serious environmental and societal concern. Soil erosion would have impact on fertility of agricultural land and quality of water. The major objective of this study was to investigate the spatial heterogeneity of annual soil erosion on the grid-cell basis in a small agricultural watershed of eastern India. The study watershed has a drainage area of 973 ha and is subdivided into three sub-watersheds namely: KGSW1, KGSW2 and KGSW3, based on the land topography and drainage network. Average annual soil erosion was estimated on 100 m×100 m grid-cells by integrating universal soil loss equation (USLE model with GIS for subsequent identification of critical erosion prone areas. It was found that 82.63% area of the total watershed falls under slight-erosion-class (0–5 t-ha−1-yr−1, 6.87% area lies under the moderate-erosion-class (5–10 t-ha−1-yr−1, 5.96% area is under high-erosion-class (10–20 t-ha−1-yr−1, 3.3% area of watershed lies under the very-high-erosion-class (20–40 t-ha−1-yr−1 and 1.24% area falls under “severe-erosion-class” (40–80 t-ha−1-yr−1. The study revealed that the sub-watershed KGSW3 is critical due to the presence of the highest number of critical erosion prone grid-cells. The sediment delivery ratio (SDR was also estimated to analyze the contribution of sediment yield at the sub-watershed level. Lowest SDR for the whole watershed as compared to sub-watersheds indicates that most of the eroded soil got deposited in rice crop check-basins before reaching the outlet. The reported results can be used for prioritizing critical erosion prone areas and for determining appropriate soil erosion prevention and control measures.

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.

Probabilistic Forecast of Wind Power Generation by Stochastic Differential Equation Models

KAUST Repository

Elkantassi, Soumaya

2017-01-01

Reliable forecasting of wind power generation is crucial to optimal control of costs in generation of electricity with respect to the electricity demand. Here, we propose and analyze stochastic wind power forecast models described by parametrized

Erosion in extruder flow

Science.gov (United States)

Kaufman, Miron; Fodor, Petru S.

A detailed analysis of the fluid flow in Tadmor's unwound channel model of the single screw extruder is performed by combining numerical and analytical methods. Using the analytical solution for the longitudinal velocity field (in the limit of zero Reynolds number) allows us to devote all the computational resources solely for a detailed numerical solution of the transversal velocity field. This high resolution 3D model of the fluid flow in a single-screw extruder allows us to identify the position and extent of Moffatt eddies that impede mixing. We further consider the erosion of particles (e.g. carbon-black agglomerates) advected by the polymeric flow. We assume a particle to be made of primary fragments bound together. In the erosion process a primary fragment breaks out of a given particle. Particles are advected by the laminar flow and they disperse because of the shear stresses imparted by the fluid. The time evolution of the numbers of particles of different sizes is described by the Bateman coupled differential equations used to model radioactivity. Using the particle size distribution we compute an entropic fragmentation index which varies from 0 for a monodisperse system to 1 for an extreme poly-disperse system.

Wind Turbine Radar Cross Section

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David Jenn

2012-01-01

Full Text Available The radar cross section (RCS of a wind turbine is a figure of merit for assessing its effect on the performance of electronic systems. In this paper, the fundamental equations for estimating the wind turbine clutter signal in radar and communication systems are presented. Methods of RCS prediction are summarized, citing their advantages and disadvantages. Bistatic and monostatic RCS patterns for two wind turbine configurations, a horizontal axis three-blade design and a vertical axis helical design, are shown. The unique electromagnetic scattering features, the effect of materials, and methods of mitigating wind turbine clutter are also discussed.

Nutrient losses by wind and water, measurements and modelling

NARCIS (Netherlands)

Visser, S.M.; Stroosnijder, L.; Chardon, W.J.

2005-01-01

In the Sahelian zone of West-Africa, erosion by both wind and water causes a serious decline in fertility of the already low fertile soils. Despite the fact that the flow of nutrients has been intensively investigated by the use of nutrient balances, little attention has been paid to the

Measurement and data analysis methods for field-scale wind erosion studies and model validation

NARCIS (Netherlands)

Zobeck, T.M.; Sterk, G.; Funk, R.F.; Rajot, J.L.; Stout, J.E.; Scott Van Pelt, R.

2003-01-01

Accurate and reliable methods of measuring windblown sediment are needed to confirm, validate, and improve erosion models, assess the intensity of aeolian processes and related damage, determine the source of pollutants, and for other applications. This paper outlines important principles to

Numerically Modeling the Erosion of Lunar Soil by Rocket Exhaust Plumes

Science.gov (United States)

2008-01-01

In preparation for the Apollo program, Leonard Roberts of the NASA Langley Research Center developed a remarkable analytical theory that predicts the blowing of lunar soil and dust beneath a rocket exhaust plume. Roberts assumed that the erosion rate was determined by the excess shear stress in the gas (the amount of shear stress greater than what causes grains to roll). The acceleration of particles to their final velocity in the gas consumes a portion of the shear stress. The erosion rate continues to increase until the excess shear stress is exactly consumed, thus determining the erosion rate. Roberts calculated the largest and smallest particles that could be eroded based on forces at the particle scale, but the erosion rate equation assumed that only one particle size existed in the soil. He assumed that particle ejection angles were determined entirely by the shape of the terrain, which acts like a ballistic ramp, with the particle aerodynamics being negligible. The predicted erosion rate and the upper limit of particle size appeared to be within an order of magnitude of small-scale terrestrial experiments but could not be tested more quantitatively at the time. The lower limit of particle size and the predictions of ejection angle were not tested. We observed in the Apollo landing videos that the ejection angles of particles streaming out from individual craters were time-varying and correlated to the Lunar Module thrust, thus implying that particle aerodynamics dominate. We modified Roberts theory in two ways. First, we used ad hoc the ejection angles measured in the Apollo landing videos, in lieu of developing a more sophisticated method. Second, we integrated Roberts equations over the lunar-particle size distribution and obtained a compact expression that could be implemented in a numerical code. We also added a material damage model that predicts the number and size of divots which the impinging particles will cause in hardware surrounding the landing

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

Directory of Open Access Journals (Sweden)

Fábio G. Pedro

2004-07-01

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

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

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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

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

Science.gov (United States)

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

2016-12-01

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

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

Science.gov (United States)

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

2018-04-01

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

Coupled Wave Energy and Erosion Dynamics along a Salt Marsh Boundary, Hog Island Bay, Virginia, USA

Directory of Open Access Journals (Sweden)

Anthony M. Priestas

2015-09-01

Full Text Available The relationship between lateral erosion of salt marshes and wind waves is studied in Hog Island Bay, Virginia USA, with high-resolution field measurements and aerial photographs. Marsh retreat is compared to wave climate calculated in the bay using the spectral wave-model Simulating Waves Nearshore (SWAN. We confirm the existence of a linear relationship between long-term salt marsh erosion and wave energy, and show that wave power can serve as a good proxy for average salt-marsh erosion rates. At each site, erosion rates are consistent across several temporal scales, ranging from months to decades, and are strongly related to wave power. On the contrary, erosion rates vary in space and weakly depend on the spatial distribution of wave energy. We ascribe this variability to spatial variations in geotechnical, biological, and morphological marsh attributes. Our detailed field measurements indicate that at a small spatial scale (tens of meters, a positive feedback between salt marsh geometry and wave action causes erosion rates to increase with boundary sinuosity. However, at the scale of the entire marsh boundary (hundreds of meters, this relationship is reversed: those sites that are more rapidly eroding have a marsh boundary which is significantly smoother than the marsh boundary of sheltered and slowly eroding marshes.

The Monsoon Erosion Pump and the Indian Monsoon since Eocene

Science.gov (United States)

Giosan, L.

2017-12-01

Lack of consensus on the Neogene establishment and evolution of the Indian Monsoon is remarkable after half a century of research. Conflicting interpretations point toward the possibility of periodic decoupling between monsoon winds and monsoon precipitation. Here I introduce the concept of a monsoon erosion pump based on terrestrial and oceanic records reconstructed from recent NGHP and IODP drilling and spanning the last 34 million years in the Bay of Bengal, Arabian and Andaman Seas. From millennial to orbital to tectonic timescales, these records suggest that vegetation land cover interacts and modulates the regime of erosion and weathering under perennial but variable monsoonal rain conditions. Under this new proposed paradigm the Indian monsoon exhibits two distinct flavours during the Neogene that can be largely explained by its heartbeat, or astronomical forcing, mediated by the global glacial state and interacting with the paleogeography of South Asia.

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

Science.gov (United States)

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

2016-12-01

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

Extent of Cropland and Related Soil Erosion Risk in Rwanda

Directory of Open Access Journals (Sweden)

Fidele Karamage

2016-06-01

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

WindPACT Reference Wind Turbines

Energy Technology Data Exchange (ETDEWEB)

Dykes, Katherine L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Rinker, Jennifer [Former National Renewable Energy Laboratory (NREL) employee

2018-04-02

To fully understand how loads and turbine cost scale with turbine size, it is necessary to have identical turbine models that have been scaled to different rated powers. The report presents the WindPACT baseline models, which are a series of four baseline models that were designed to facilitate investigations into the scalings of loads and turbine cost with size. The models have four different rated powers (750 kW, 1.5 MW, 3.0 MW, and 5.0 MW), and each model was designed to its specified rated power using the same design methodology. The models were originally implemented in FAST_AD, the predecessor to NREL's open-source wind turbine simulator FAST, but have yet to be implemented in FAST. This report contains the specifications for all four WindPACT baseline models - including structural, aerodynamic, and control specifications - along with the inherent assumptions and equations that were used to calculate the model parameters. It is hoped that these baseline models will serve as extremely useful resources for investigations into the scalings of costs, loads, or optimization routines.

Temporal and spatial variation of maximum wind speed days during the past 20 years in major cities of Xinjiang

Science.gov (United States)

Baidourela, Aliya; Jing, Zhen; Zhayimu, Kahaer; Abulaiti, Adili; Ubuli, Hakezi

2018-04-01

Wind erosion and sandstorms occur in the neighborhood of exposed dust sources. Wind erosion and desertification increase the frequency of dust storms, deteriorate air quality, and damage the ecological environment and agricultural production. The Xinjiang region has a relatively fragile ecological environment. Therefore, the study of the characteristics of maximum wind speed and wind direction in this region is of great significance to disaster prevention and mitigation, the management of activated dunes, and the sustainable development of the region. Based on the latest data of 71 sites in Xinjiang, this study explores the temporal evolution and spatial distribution of maximum wind speed in Xinjiang from 1993 to 2013, and highlights the distribution of annual and monthly maximum wind speed and the characteristics of wind direction in Xinjiang. Between 1993 and 2013, Ulugchat County exhibited the highest number of days with the maximum wind speed (> 17 m/s), while Wutian exhibited the lowest number. In Xinjiang, 1999 showed the highest number of maximum wind speed days (257 days), while 2013 showed the lowest number (69 days). Spring and summer wind speeds were greater than those in autumn and winter. There were obvious differences in the direction of maximum wind speed in major cities and counties of Xinjiang. East of the Tianshan Mountains, maximum wind speeds are mainly directed southeast and northeast. North and south of the Tianshan Mountains, they are mainly directed northwest and northeast, while west of the Tianshan Mountains, they are mainly directed southeast and northwest.

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

Science.gov (United States)

Schönbrodt, Sarah; Behrens, Thorsten; Scholten, Thomas

2010-05-01

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

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

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

Science.gov (United States)

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.

MODELLING OF TURBULENT WAKE FOR TWO WIND TURBINES

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Arina S. Kryuchkova

2018-01-01

Full Text Available The construction of several large wind farms (The Ulyanovsk region, the Republic of Adygea, the Kaliningrad region, the North of the Russian Federation is planned on the territory of the Russian Federation in 2018–2020. The tasks, connected with the design of new wind farms, are currently important. One of the possible direction in the design is connected with mathematical modeling. Large eddy method (eddy-resolving simulation, developed within the Computational Fluid Dynamics, allows to reproduce unsteady structure of the flow in details and define various integrated characteristics for wind turbines. The mathematical model included the main equations of continuity and momentum equations for incompressible viscous flow. The large-scale vortex structures were calculated by means of integration the filtered equations. The calculation was carried out using lagrangian dynamic Smagorinsky’s model to define turbulent subgrid viscosity. The parallelepiped-shaped numerical domain and 3 different unstructured meshes (with 2,4,8 million cells were used for numerical simulation.The geometrical parameters of wind turbine were set proceeding to open sources for BlindTest 2–4 project from Internet. All physical values were defined at the center of computational cell. The approximation of items in the equations was performed with the second order of accuracy for time and space. The equations for coupling of velocity, pressure were solved by means of iterative algorithm PIMPLE. The total quantity of the calculated physical values at each time step was equal 18. So, the resources of a high performance computer were required. As a result of flow simulation in the wake for two three-bladed wind turbines the average and instantaneous values of velocity, pressure, subgrid kinetic energy, turbulent viscosity, components of stress tensor were calculated. The received results qualitatively matching the known results of experiment and numerical simulation testify

Consideration of some fundamental erosion processes encountered in hypervelocity electromagnetic propulsion

International Nuclear Information System (INIS)

Buckingham, A.C.; Hawke, R.S.

1982-01-01

Experimental and theoretical research has been conducted jointly at the Livermore and Los Alamos National laboratories on dc electromagnetic railgun Lorentz accelerators. Pellets weighing a few grams to tens of grams have been launched at velocities up to better than 11 km/s. The research is addressed to attaining repeated launches of samples at hypervelocity in target impact experiments. In these experiments, shock-induced pressures in the tens of megabars range are obtained for high pressure equation-of-state research. Primary energy sources of the order of several hundred kJ to a MJ and induction currents of the order of 1 or more MA are necessary for these launches. Erosion and deformation of the conductor rails and the accelerated sample material are continuing problems. The heating, stress, and erosion resulting from simultaneous imposition of rail induction current, dense plasma (armature) interaction, current distribution, magnetic field stresses and projectile/rail contact friction are examined. It is found that while frictional heating and consequent sliding contact erosion are minor contributors to the overall erosion process, the same cannot be said for plasma impingement, penetration, and almost simultaneous induction current (Joule) heating

Assessing the effects of land-use changes on annual average gross erosion

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Armando Brath

2002-01-01

Full Text Available The effects of land-use changes on potential annual gross erosion in the uplands of the Emilia-Romagna administrative region, a broad geographical area of some 22 000 km2 in northern-central Italy, have been analysed by application of the Universal Soil Loss Equation (USLE. The presence of an extended mountain chain, particularly subject to soil erosion, makes the estimation of annual gross erosion relevant in defining regional soil-conservation strategies. The USLE, derived empirically for plots, is usually applied at the basin scale. In the present study, the method is implemented in a distributed framework for the hilly and mountainous portion of Emilia-Romagna through a discretisation of the region into elementary square cells. The annual gross erosion is evaluated by combining morphological, pedological and climatic information. The stream network and the tributary area drained by each elementary cell, which are needed for the local application of the USLE, are derived automatically from a Digital Elevation Model (DEM of grid size 250 x 250 m. The rainfall erosivity factor is evaluated from local estimates of rainfall of six-hour storm duration and two-year return period. The soil erodibility and slope length-steepness factors are derived from digital maps of land use, pedology and geomorphology. Furthermore, historical land-use maps of the district of Bologna (a large portion — 3720 km2 — of the area under study, allow the effect of actual land use changes on the soil erosion process to be assessed. The analysis shows the influence of land-use changes on annual gross erosion as well as the increasing vulnerability of upland areas to soil erosion processes during recent decades. Keywords: USLE, gross erosion, distributed modelling, land use changes, northern-central Italy

EDDA 1.0: integrated simulation of debris flow erosion, deposition and property changes

Science.gov (United States)

Chen, H. X.; Zhang, L. M.

2015-03-01

Debris flow material properties change during the initiation, transportation and deposition processes, which influences the runout characteristics of the debris flow. A quasi-three-dimensional depth-integrated numerical model, EDDA (Erosion-Deposition Debris flow Analysis), is presented in this paper to simulate debris flow erosion, deposition and induced material property changes. The model considers changes in debris flow density, yield stress and dynamic viscosity during the flow process. The yield stress of the debris flow mixture determined at limit equilibrium using the Mohr-Coulomb equation is applicable to clear water flow, hyper-concentrated flow and fully developed debris flow. To assure numerical stability and computational efficiency at the same time, an adaptive time stepping algorithm is developed to solve the governing differential equations. Four numerical tests are conducted to validate the model. The first two tests involve a one-dimensional debris flow with constant properties and a two-dimensional dam-break water flow. The last two tests involve erosion and deposition, and the movement of multi-directional debris flows. The changes in debris flow mass and properties due to either erosion or deposition are shown to affect the runout characteristics significantly. The model is also applied to simulate a large-scale debris flow in Xiaojiagou Ravine to test the performance of the model in catchment-scale simulations. The results suggest that the model estimates well the volume, inundated area, and runout distance of the debris flow. The model is intended for use as a module in a real-time debris flow warning system.

The Impact of Farming and Land Ownership on Soil Erosion

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Olga Čermáková

2014-01-01

Full Text Available The aim of this paper was to compare two methods of farming, especially their effect on water soil erosion. The examined methods were (1 large-scale farming, where more than 50% of the land was leased, and (2 small-scale farming, where the land was almost exclusively privately owned. The research area was 8 cadastres in the district of Hodonín, South Moravia, Czech Republic. In these cadastres 48 land blocks representing both large-scale and small-scale farming (i.e. owners and tenants were chosen. The long-term average annual soil loss caused by water erosion (G was calculated using the erosion model USLE 2D and ArcGIS 10.1. The nonparametric Mann-Whitney test was used for the statistical evaluation of the data. The difference between the soil loss (G on land blocks farmed by small producers (owners and large producers (tenants was significant (p < 0.05. Differences between the values of the cropping-management factor (C were not statistically significant (p = 0.054. Based on the analysis of other variables in the USLE equation it can be stated that a continuous slope length, conditioned by the size of land blocks, played an important role in the amount of soil loss caused by water erosion. Above all, to protect the soil from erosion and maintain soil quality it is necessary to reduce the size of land blocks farmed by tenants and improve the crop rotation systems.

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

Science.gov (United States)

Ferreira, Vera; Panagopoulos, Thomas

2014-07-01

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

Application of experimental soil erosion models (USLE, RUSLE) in Jordan: A review

Science.gov (United States)

Ramzi, A. A.; Ayu, A. W.; Mohm, A. A.; Fahmi, R. M.; Ibrahim, O. M.

2017-09-01

In most of the existing models designed for the soil erosion experiment are moderately simplistic, which consistently, have been extensively practiced in many parts of the world. In reality, within the content of this study, the practical occurrences of the Universal Soil Loss Equation (USLE) and that of the Revised Universal Soil Loss Equation (RUSLE) in Jordan were explored. This is obvious as RUSLE portrayed a product adaptation of a significantly enhanced USLE. In Jordan, various research accomplishments were made to decide the nearby values of the USLE components, demonstrating its, potential for use outside its birthplace nation. Entirely, this study found the soil experimental models stand to be mere demonstrating procedures or structures, instead of being the punctual robotic portrayals of the framework, and that perhaps; make no claim of universal comprehensiveness. In any case, with these identified weaknesses, sub-models were found to be utilized in order to give the best practical gauges of the disintegration of the sheet erosion within the Jordanian context. Most often, the spatial index circulation of the soil misfortune of the USLE is viewed as a valuable model that separate regions of high and low disintegration of the erosion potential. In this case, USLE is more generally known and utilized soil erosion condition on the planet. However, no specific model is ever, generally actualized. Although, the USLE model ended to be a promising instrument, as it gives a dynamic way to deal with foreseeing the misfortune of the soil erosion. This study, notwithstanding, perceives there is still a need to further enhanced a check of the RUSLE and USLE outcomes in Jordan. This study sees, by the virtues of hypothetical assessment and affectability in terms of the investigation performed have obviously demonstrated the benefit of the most adaptable and element structure of RUSLE against the strict exact structures of the USLE. Albeit, an exact model could be

Differential erosion and the formation of layered yardangs in the Loulan region (Lop Nur), eastern Tarim Basin

Science.gov (United States)

Lin, Yongchong; Xu, Lishuai; Mu, Guijin

2018-02-01

Yardangs are a type of wind-sculpted landform which generally form in hyper-arid regions. Several factors affect the development of yardangs, and the relative importance of these factors likely varies with differences in regional environmental factors. In the Loulan region of Lop Nur, wind dynamics are the principal factor affecting the development of yardangs. However, layered yardangs, which have undergone a unique form of differential erosion, are common in the region. These erosional landforms differ from typical yardangs which are eroded solely by abrasion and deflation. We conducted field and laboratory investigations of layered yardangs to determine their origin. The results indicate that there are two types of strata comprising the yardangs: uncompacted sand-silt layers, with a lower carbonate content; and compacted clay-silt layers, with a higher carbonate content. Both types of strata are horizontal and occur in alternating layers. This type of structure enables the wind to more easily erode the less resistant sand-silt layers at different heights, leaving the more resistant compacted clay-silt layers relatively intact. Eventually the undercut remnant clay-silt layers collapse once the weight of the suspended strata exceeds their elastic resistance (more than 90% of the fallen blocks have length/thickness ratios between 1.2 and 2.5). Therefore, in addition to wind dynamics, the lithology and structure of the strata are important factors affecting the development of the layered yardangs. This type of differential erosion accelerates the development of the yardangs in the Loulan region.

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

Science.gov (United States)

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

2017-07-01

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

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

Directory of Open Access Journals (Sweden)

C. Zeng

2017-07-01

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

Nonmonotonic and spatial-temporal dynamic slope effects on soil erosion during rainfall-runoff processes

Science.gov (United States)

Wu, Songbai; Yu, Minghui; Chen, Li

2017-02-01

The slope effect on flow erosivity and soil erosion still remains a controversial issue. This theoretical framework explained and quantified the direct slope effect by coupling the modified Green-Ampt equation accounting for slope effect on infiltration, 1-D kinematic wave overland flow routing model, and WEPP soil erosion model. The flow velocity, runoff rate, shear stress, interrill, and rill erosion were calculated on 0°-60° isotropic slopes with equal horizontal projective length. The results show that, for short-duration rainfall events, the flow erosivity and erosion amounts exhibit a bell-shaped trend which first increase with slope gradient, and then decrease after a critical slope angle. The critical slope angles increase significantly or even vanish with increasing rainfall duration but are nearly independent of the slope projective length. The soil critical shear stress, rainfall intensity, and temporal patterns have great influences on the slope effect trend, while the other soil erosion parameters, soil type, hydraulic conductivity, and antecedent soil moisture have minor impacts. Neglecting the slope effect on infiltration would generate smaller erosion and reduce critical slope angles. The relative slope effect on soil erosion in physically based model WEPP was compared to those in the empirical models USLE and RUSLE. The trends of relative slope effect were found quite different, but the difference may diminish with increasing rainfall duration. Finally, relatively smaller critical slope angles could be obtained with the equal slope length and the range of variation provides a possible explanation for the different critical slope angles reported in previous studies.

Comparative study of the behavior of wind-turbines in a wind farm

Energy Technology Data Exchange (ETDEWEB)

Migoya, Emilio; Crespo, Antonio; Garcia, Javier; Manuel, Fernando; Jimenez, Angel [Universidad Politecnica de Madrid (UPM), Madrid (Spain). Departamento de Ingenieria Energetica y Fluidomecanica, Laboratorio de Mecanica de Fluidos; Moreno, Fermin [Comision Nacional de la Energia, Madrid (Spain); Costa, Alexandre [Energia Eolica, Division de Energias Renovables, CIEMAT, Madrid (Spain)

2007-10-15

The Sotavento wind farm is an experimental wind farm which has different types of wind turbines. It is located in an area whose topography is moderately complex, and where wake effects can be significant. One of the objectives of Sotavento wind farm is to compare the performances of the different machines; particularly regarding power production, maintenance and failures. However, because of wakes and topography, the different machines are not working under identical conditions. Two linearized codes have been used to estimate topography effects: UPMORO and WAsP. For wind directions in which topography is abrupt, the non-linear flow equations have been solved with the commercial code FLUENT, although the results are only qualitatively used. For wake effects, the UPMPARK code has been applied. As a result, the incident velocity over each wind turbine is obtained, and the power production is estimated by means of the power curve of each machine. Experimental measurements give simultaneously the wind characteristics at the measuring stations, the wind velocity, at the nacelle anemometer, and the power production of each wind turbine. These experimental results are employed to validate the numerical predictions. The main objective of this work is to deduce and validate a relationship between the wind characteristics measured in the anemometers and the wind velocity and the power output in each machine. (author)

Evaluation of the rusle and disturbed wepp erosion models for predicting soil loss in the first year after wildfire in NW Spain.

Science.gov (United States)

Fernández, Cristina; Vega, José A

2018-05-04

Severe fire greatly increases soil erosion rates and overland-flow in forest land. Soil erosion prediction models are essential for estimating fire impacts and planning post-fire emergency responses. We evaluated the performance of a) the Revised Universal Soil Loss Equation (RUSLE), modified by inclusion of an alternative equation for the soil erodibility factor, and b) the Disturbed WEPP model, by comparing the soil loss predicted by the models and the soil loss measured in the first year after wildfire in 44 experimental field plots in NW Spain. The Disturbed WEPP has not previously been validated with field data for use in NW Spain; validation studies are also very scarce in other areas. We found that both models underestimated the erosion rates. The accuracy of the RUSLE model was low, even after inclusion of a modified soil erodibility factor accounting for high contents of soil organic matter. We conclude that neither model is suitable for predicting soil erosion in the first year after fire in NW Spain and suggest that soil burn severity should be given greater weighting in post-fire soil erosion modelling. Copyright © 2018 Elsevier Inc. All rights reserved.

The Crab Pulsar and Relativistic Wind

Science.gov (United States)

Coroniti, F. V.

2017-12-01

The possibility that the Crab pulsar produces a separated ion-dominated and pair-plasma-dominated, magnetically striped relativistic wind is assessed by rough estimates of the polar cap acceleration of the ion and electron primary beams, the pair production of secondary electrons and positrons, and a simple model of the near-magnetosphere-wind zone. For simplicity, only the orthogonal rotator is considered. Below (above) the rotational equator, ions (electrons) are accelerated in a thin sheath, of order (much less than) the width of the polar cap, to Lorentz factor {γ }i≈ (5{--}10)× {10}7({γ }e≈ {10}7). The accelerating parallel electric field is shorted out by ion-photon (curvature synchrotron) pair production. With strong, but fairly reasonable, assumptions, a set of general magnetic geometry relativistic wind equations is derived and shown to reduce to conservation relations that are similar to those of the wind from a magnetic monopole. The strength of the field-aligned currents carried by the primary beams is determined by the wind’s Alfvén critical point condition to be about eight times the Goldreich-Julian value. A simple model for the transition from the dipole region wind to the asymptotic monopole wind zone is developed. The asymptotic ratio of Poynting flux to ion (pair plasma) kinetic energy flux—the wind {σ }w∞ -parameter—is found to be of order {σ }w∞ ≈ 1/2({10}4). The far wind zone is likely to be complex, with the ion-dominated and pair-plasma-dominated magnetic stripes merging, and the oppositely directed azimuthal magnetic fields annihilating.

Monitoring Soil Erosion of a Burn Site in the Central Basin and Range Ecoregion: Final Report on Measurements at the Gleason Fire Site, Nevada

Energy Technology Data Exchange (ETDEWEB)

Miller, Julianne [DRI; Etyemezian, Vicken [DRI; Shillito, Rose [DRI; Cablk, Mary [DRI; Fenstermaker, Lynn [DRI; Shafer, David [DOE Legacy Management

2013-10-01

The increase in wildfires in arid and semi-arid parts of Nevada and elsewhere in the southwestern United States has implications for post-closure management and long-term stewardship for Soil Corrective Action Units (CAUs) on the Nevada National Security Site (NNSS) for which the Nevada Field Office of the United States Department of Energy, National Nuclear Security Administration has responsibility. For many CAUs and Corrective Action Sites, where closure-in-place alternatives are now being implemented or considered, there is a chance that these sites could burn over at some time while they still pose a risk to the environment or human health, given the long half lives of some of the radionuclide contaminants. This study was initiated to examine the effects and duration of wildfire on wind and water erodibility on sites analogous to those that exist on the NNSS. The data analyzed herein were gathered at the prescribed Gleason Fire site near Ely, Nevada, a site comparable to the northern portion of the NNSS. Quantification of wind erosion was conducted with a Portable In-Situ Wind ERosion Lab (PI-SWERL) on unburned soils, and on interspace and plant understory soils within the burned area. The PI-SWERL was used to estimate emissions of suspendible particles (particulate matter with aerodynamic diameters less than or equal to 10 micrometers) at different wind speeds. Filter samples, collected from the exhaust of the PI-SWERL during measurements, were analyzed for chemical composition. Based on nearly three years of data, the Gleason Fire site does not appear to have returned to pre burn wind erosion levels. Chemical composition data of suspendible particles are variable and show a trend toward pre-burn levels, but provide little insight into how the composition has been changing over time since the fire. Soil, runoff, and sediment data were collected from the Gleason Fire site to monitor the water erosion potential over the nearly three-year period. Soil

[Dynamics of soil erosion at upper reaches of Minjiang River based on GIS].

Science.gov (United States)

He, Xingyuan; Hu, Zhibi; Li, Yuehui; Hu, Yuanman

2005-12-01

Based on TM and ETM imagines, and employing GIS technique and empirical Revised Universal Soil Loss Equation (RUSLE) model, this paper studied the dynamics of soil erosion at the upper reaches of Minjiang River during three typical periods, with the main affecting factors analyzed. The results showed that the soil erosion area was increased by 1.28%, 1.84 % and 1.70% in 1986, 1995 and 2000, respectively. The average erosion modulus was increased from 832.64 t x km(-2) x yr(-1) in 1986 to 1048.74 t x km(-2) yr(-2) in 1995 and reached 1362.11 t x km(-2) yr(-1) in 2000, and soil loss was mainly of slight and light erosion, companying with a small quantity of middling erosion. The area of soil erosion was small, and the degree was light. There was a significant correlation between slope and soil loss, which mainly happened in the regions with a slope larger than 25 degrees, and accounted for 93.65%, 93.81% and 92.71% of the total erosion in 1986, 1995 and 2000, respectively. As for the altitude, middling, semi-high and high mountains and dry valley were liable to soil erosion, which accounted for 98.21%, 97.63% and 99.27% of the total erosion in 1986, 1995 and 2000, respectively. Different vegetation had a significant effect on soil erosion, and shrub and newly restored forest were the main erosion area. Excessive depasture not only resulted in the degradation of pasture, but also led to slight soil erosion. Land use type and soil type also contributed to soil loss, among which, dry-cinnamon soil and calcic gray-cinnamon soil were the most dangerous ones needing more protection. Soil loss was also linearly increased with increasing population and households, which suggested that the increase of population and households was the driving factor for soil loss increase in this area.

Modelling approach for the rainfall erosivity index in sub-humid urban areas in northern Algeria

Science.gov (United States)

Touaibia, I.; Abderrahmane Guenim, N.; Touaibia, B.

2014-09-01

This work presents an approach for storm water erosivity index modelling in the absence of measurement in an urban area, in a sub-humid climate. In torrential storms, floods, loaded with sediments, obstruct storm water drainage. With the aim of estimating the amount of sediment that can be deposited on a stretch of road, adjacent to the study area, the erosivity index is determined from a count of 744 rain showers recorded over a period of 19 years. The Universal Soil Loss Equation (USLE) of Wischmeier and Smith is applied, where only the index of erosivity is calculated; it is based on the intensity of the rain starting the process of erosion in the basin. Functional relations are required between this factor and the explanatory variables. A power type regression model is reached, making it possible to bring a decision-making aid in absences of measurements.

Modelling approach for the rainfall erosivity index in sub-humid urban areas in northern Algeria

Directory of Open Access Journals (Sweden)

I. Touaibia

2014-09-01

Full Text Available This work presents an approach for storm water erosivity index modelling in the absence of measurement in an urban area, in a sub-humid climate. In torrential storms, floods, loaded with sediments, obstruct storm water drainage. With the aim of estimating the amount of sediment that can be deposited on a stretch of road, adjacent to the study area, the erosivity index is determined from a count of 744 rain showers recorded over a period of 19 years. The Universal Soil Loss Equation (USLE of Wischmeier and Smith is applied, where only the index of erosivity is calculated; it is based on the intensity of the rain starting the process of erosion in the basin. Functional relations are required between this factor and the explanatory variables. A power type regression model is reached, making it possible to bring a decision-making aid in absences of measurements.

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

International Nuclear Information System (INIS)

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

2012-01-01

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

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.

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.

Rainfall Erosivity in Europe

DEFF Research Database (Denmark)

Panagos, Panos; Ballabio, Cristiano; Borrelli, Pasquale

2015-01-01

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

Improved USLE-K factor prediction: A case study on water erosion areas in China

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Bin Wang

2016-09-01

Full Text Available Soil erodibility (K-factor is an essential factor in soil erosion prediction and conservation practises. The major obstacles to any accurate, large-scale soil erodibility estimation are the lack of necessary data on soil characteristics and the misuse of variable K-factor calculators. In this study, we assessed the performance of available erodibility estimators Universal Soil Loss Equation (USLE, Revised Universal Soil Loss Equation (RUSLE, Erosion Productivity Impact Calculator (EPIC and the Geometric Mean Diameter based (Dg model for different geographic regions based on the Chinese soil erodibility database (CSED. Results showed that previous estimators overestimated almost all K-values. Furthermore, only the USLE and Dg approaches could be directly and reliably applicable to black and loess soil regions. Based on the nonlinear best fitting techniques, we improved soil erodibility prediction by combining Dg and soil organic matter (SOM. The NSE, R2 and RE values were 0.94, 0.67 and 9.5% after calibrating the results independently; similar model performance was showed for the validation process. The results obtained via the proposed approach were more accurate that the former K-value predictions. Moreover, those improvements allowed us to effectively establish a regional soil erodibility map (1:250,000 scale of water erosion areas in China. The mean K-value of Chinese water erosion regions was 0.0321 (t ha h·(ha MJ mm−1 with a standard deviation of 0.0107 (t ha h·(ha MJ mm−1; K-values present a decreasing trend from North to South in water erosion areas in China. The yield soil erodibility dataset also satisfactorily corresponded to former K-values from different scales (local, regional, and national.

A new perspective on soil erosion: exploring a thermodynamic approach in a small area of the River Inn catchment

Science.gov (United States)

Reid, Lucas; Scherer, Ulrike; Zehe, Erwin

2016-04-01

Soil erosion modeling has always struggled with compensating for the difference in time and spatial scale between model, data and the actual processes involved. This is especially the case with non-event based long-term models based on the Universal Soil Loss Equation (USLE), yet USLE based soil erosion models are among the most common and widely used for they have rather low data requirements and can be applied to large areas. But the majority of mass from soil erosion is eroded within short periods of times during heavy rain events, often within minutes or hours. Advancements of the USLE (eg. the Modified Universal Soil Loss Equation, MUSLE) allow for a daily time step, but still apply the same empirical methods derived from the USLE. And to improve the actual quantification of sediment input into rivers soil erosion models are often combined with a Sediment Delivery Ratio (SDR) to get results within the range of measurements. This is still a viable approach for many applications, yet it leaves much to be desired in terms of understanding and reproducing the processes behind soil erosion and sediment input into rivers. That's why, instead of refining and retuning the existing methods, we explore a more comprehensive, physically consistent description on soil erosion. The idea is to describe soil erosion as a dissipative process (Kleidon et al., 2013) and test it in a small sub-basin of the River Inn catchment area in the pre-Alpine foothills. We then compare the results to sediment load measurements from the sub-basin and discuss the advantages and issues with the application of such an approach.

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

Science.gov (United States)

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

2015-01-01

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

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

Directory of Open Access Journals (Sweden)

Mustafa Tüfekçioğlu

2016-10-01

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

Experimental implementation of parallel riverbed erosion to study vegetation uprooting by flow

Science.gov (United States)

Perona, Paolo; Edmaier, Katharina; Crouzy, Benoît

2014-05-01

In nature, flow erosion leading to the uprooting of vegetation is often a delayed process that gradually reduces anchoring by root exposure and correspondingly increases drag on the exposed biomass. The process determining scouring or deposition of the riverbed, and consequently plant root exposure is complex and scale dependent. At the local scale, it is hydrodynamically driven and depends on obstacle porosity, as well as sediment vs obstacle size ratio. At a larger scale it results from morphodynamic conditions, which mostly depend on riverbed topography and stream bedload transport capacity. In the latter case, ablation of sediment gradually reduces local bed elevation around the obstacle at a scale larger than the obstacle size, and uprooting eventually occurs when flow drag exceeds the residual anchoring. Ideally, one would study the timescales of vegetation uprooting by flow by inducing parallel bed erosion. This condition is not trivial to obtain experimentally because bed elevation adjustments occur in relation to longitudinal changes in sediment apportion as described by Exner's equation. In this work, we study the physical conditions leading to parallel bed erosion by reducing Exner equation closed for bedload transport to a nonlinear partial differential equation, and showing that this is a particular "boundary value" problem. Eventually, we use the data of Edmaier (2014) from a small scale mobile-bed flume setup to verify the proposed theoretical framework, and to show how such a simple experiment can provide useful insights into the timescales of the uprooting process (Edmaier et al., 2011). REFERENCES - Edmaier, K., P. Burlando, and P. Perona (2011). Mechanisms of vegetation uprooting by flow in alluvial non-cohesive sediment. Hydrology and Earth System Sciences, vol. 15, p. 1615-1627. - Edmaier, K. Uprooting mechanisms of juvenile vegetation by flow. PhD thesis, EPFL, in preparation.

On multivariate imputation and forecasting of decadal wind speed missing data.

Science.gov (United States)

Wesonga, Ronald

2015-01-01

This paper demonstrates the application of multiple imputations by chained equations and time series forecasting of wind speed data. The study was motivated by the high prevalence of missing wind speed historic data. Findings based on the fully conditional specification under multiple imputations by chained equations, provided reliable wind speed missing data imputations. Further, the forecasting model shows, the smoothing parameter, alpha (0.014) close to zero, confirming that recent past observations are more suitable for use to forecast wind speeds. The maximum decadal wind speed for Entebbe International Airport was estimated to be 17.6 metres per second at a 0.05 level of significance with a bound on the error of estimation of 10.8 metres per second. The large bound on the error of estimations confirms the dynamic tendencies of wind speed at the airport under study.

Predicted erosion and sediment delivery of fallout plutonium

International Nuclear Information System (INIS)

Foster, G.R.; Hakonson, T.E.

1984-01-01

Plutonium (Pu) from fallout after atmospheric explosion of nuclear weapons in the 1950s and 1960s is being redistributed over the landscape by soil erosion and carried on sediment by streams to oceans. Erosion rates computed with the Universal Soil Loss Equation for about 200,000 sample points on nonfederal land across the US were used to estimate Pu removal rates by soil erosion by water, Pu delivery in several major rivers, and concentration of Pu on the transported sediment. Estimates of average annual Pu delivery on sediment ranged from 0.002% of the initial fallout Pu inventory for the Savannah River basin to 0.08% for the Mississippi River basin. If the deposition of Pu had been uniformly 37 Bq/m 2 , the estimated Pu activity on suspended sediment ranged from about 0.26 Bq/kg of sediment for the Savannah River basin to 0.52 Bq/kg for the Columbia and Rio Grande river basins. After 1000 yr, about 9 to 48% of the initial Pu inventory will remain in US soils that are eroding. Much of the Pu on eroded sediment will travel only a short distance from its origin before its host sediment particles are deposited and permanently located, at least for a few hundred years. As much as 90% of the initially deposited Pu will remain, redistributed over the landscape by erosion and deposition. Although the delivery rate of Pu by rivers will not decrease greatly in the next 100 yr, a significant decrease will likely occur by 1000 yr

Review of climatic input data for wind load design in accordance with SANS 10160-3

CSIR Research Space (South Africa)

Goliger, Adam MW

2017-12-01

Full Text Available factor QWE that provides for the wind engineering procedures, such as the wind speed profile and pressure coefficients. The characteristic wind load is then given by Equation 4, where CoV is the coefficient of variation (σV/µV): QW,k = QWE (µV + 2....59 σV)2 = QWE µVk2(1+ 2.59 CoVV)2 (6) Design wind load The design wind load can be obtained by determining the wind speed according to Equation 4 for an exceedance probability (PF) that corresponds with the appropriate target reliability (β...

Modeling and implementation of wind shear data

Science.gov (United States)

Frost, Walter

1987-01-01

The problems of implementing the JAWS wind shear data are discussed. The data sets are described from the view of utilizing them in an aircraft performance computer program. Then, some of the problems of nonstandard procedures are described in terms of programming the equations of aircraft motion when the effects of temporal and spatially variable winds are included. Finally, some of the computed effects of the various wind shear terms are shown.

Durability of Compressed Earth Bricks: Assessing Erosion Resistance Using the Modified Spray Testing

Directory of Open Access Journals (Sweden)

Malarvizhi Baskaran

2010-11-01

Full Text Available The discussion in this paper is part of research directed at establishing optimal stabilization strategy for compressed bricks. The deployment context for the use of the compressed bricks was Dar es Salaam (Tanzania where manually fabricated bricks are increasingly being used in low cost housing units. This discussion specifically focuses on strategies that can be used to counter deterioration due to wind-driven rain erosion. The impact of using cement, lime, fiber and a commercial stabilizing fluid was assessed. Factory-produced bricks were used for benchmarking. The durability of the bricks was assessed using the “modified” Bulletin 5 Spray Test. The different brick specimens were sprayed with water at 2.07 MPa and 4.14 MPa over one-hour time period while measuring the depth of erosion every 15 minutes. Factory-produced bricks hardly eroded at both 2.07 MPa and 4.14 MPa pressure levels. The maximum depth of erosion for Soil-Cement bricks ranged from a maximum of 0.5 mm at 2.07 MPa water pressure to 0.8 mm at 4.14 MPa. The maximum and minimum depths of erosion for Soil-Cement-Lime bricks were 25mm and 17 mm respectively. The inclusion of natural fiber in the bricks resulted in a sharp increase of the erosion depth to a maximum of 40 mm at 2.07 MPa and 55 mm at 4.14 Mpa. As the use of natural fibers and lime enhances some physio-mechanical properties, further research is necessary to determine ways of achieving this goal while maintaining acceptable levels of erosion resistance.

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

Science.gov (United States)

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

2014-08-01

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

Surface kinetic roughening caused by dental erosion: An atomic force microscopy study

Science.gov (United States)

Quartarone, Eliana; Mustarelli, Piercarlo; Poggio, Claudio; Lombardini, Marco

2008-05-01

Surface kinetic roughening takes place both in case of growth and erosion processes. Teeth surfaces are eroded by contact with acid drinks, such as those used to supplement mineral salts during sporting activities. Calcium-phosphate based (CPP-ACP) pastes are known to reduce the erosion process, and to favour the enamel remineralization. In this study we used atomic force microscopy (AFM) to investigate the surface roughening during dental erosion, and the mechanisms at the basis of the protection role exerted by a commercial CPP-ACP paste. We found a statistically significant difference (p<0.01) in the roughness of surfaces exposed and not exposed to the acid solutions. The treatment with the CPP-ACP paste determined a statistically significant reduction of the roughness values. By interpreting the AFM results in terms of fractal scaling concepts and continuum stochastic equations, we showed that the protection mechanism of the paste depends on the chemical properties of the acid solution.

A model for hydrolytic degradation and erosion of biodegradable polymers.

Science.gov (United States)

Sevim, Kevser; Pan, Jingzhe

2018-01-15

For aliphatic polyesters such as PLAs and PGAs, there is a strong interplay between the hydrolytic degradation and erosion - degradation leads to a critically low molecular weight at which erosion starts. This paper considers the underlying physical and chemical processes of hydrolytic degradation and erosion. Several kinetic mechanisms are incorporated into a mathematical model in an attempt to explain different behaviours of mass loss observed in experiments. In the combined model, autocatalytic hydrolysis, oligomer production and their diffusion are considered together with surface and interior erosion using a set of differential equations and Monte Carlo technique. Oligomer and drug diffusion are modelled using Fick's law with the diffusion coefficients dependent on porosity. The porosity is due to the formation of cavities which are a result of polymer erosion. The model can follow mass loss and drug release up to 100%, which cannot be explained using a simple reaction-diffusion. The model is applied to two case studies from the literature to demonstrate its validity. The case studies show that a critical molecular weight for the onset of polymer erosion and an incubation period for the polymer dissolution are two critical factors that need to be considered when predicting mass loss and drug release. In order to design bioresorbable implants, it is important to have a mathematical model to predict polymer degradation and corresponding drug release. However, very different behaviours of polymer degradation have been observed and there is no single model that can capture all these behaviours. For the first time, the model presented in this paper is capable of capture all these observed behaviours by switching on and off different underlying mechanisms. Unlike the existing reaction-diffusion models, the model presented here can follow the degradation and drug release all the way to the full disappearance of an implant. Crown Copyright © 2017. Published by

Application of a fuzzy cognitive map based on a structural equation model for the identification of limitations to the development of wind power

International Nuclear Information System (INIS)

Huang, Shih-Chieh; Lo, Shang-Lien; Lin, Yen-Ching

2013-01-01

Despite numerous researchers having investigating the development of wind power, the correlation between the elements influencing wind power development has often been ignored. Hence, this research hopes to incorporate both structural equation model (SEM) and fuzzy cognitive map (FCM) to identify a mutual relationship between the various elements, so as to provide feasible recommendations for management strategies. Initially, SEM is used for identification of correlation between the elements and indicating their direction and strength. A standardized causal coefficient from SEM was then used to create an FCM illustrating the effect of the status of one component on the status of another component. The research results pointed out that “policy” would be the major challenge faced by wind power development, as well as the main cause for other obstructions. Therefore, under the objective of maximizing economic benefits, short-term strategies can adopt suitable measures for the two dimensions of “technology” and “environment”; and while mid-term strategies must consider the indirect influences from “social” dimension, long-term strategies must work on “policy”. - Highlights: • Apply SEM to explain interrelationships between the obstacles of wind power. • Adopt ‘what if’ simulation analysis to explore the optimal management strategies. • Intermediary variables were existed in the potential paths. • The results prove that correlations do exist between the obstacles. • The “policy aspect” is the main obstacle faced by wind power

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

Energy Technology Data Exchange (ETDEWEB)

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

1993-07-01

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

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

Directory of Open Access Journals (Sweden)

Junior Cesar Avanzi

2013-10-01

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

Three-fluid, three-dimensional magnetohydrodynamic solar wind model with eddy viscosity and turbulent resistivity

Energy Technology Data Exchange (ETDEWEB)

Usmanov, Arcadi V.; Matthaeus, William H. [Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Goldstein, Melvyn L., E-mail: arcadi.usmanov@nasa.gov [Code 672, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2014-06-10

We have developed a three-fluid, three-dimensional magnetohydrodynamic solar wind model that incorporates turbulence transport, eddy viscosity, turbulent resistivity, and turbulent heating. The solar wind plasma is described as a system of co-moving solar wind protons, electrons, and interstellar pickup protons, with separate energy equations for each species. Numerical steady-state solutions of Reynolds-averaged solar wind equations coupled with turbulence transport equations for turbulence energy, cross helicity, and correlation length are obtained by the time relaxation method in the corotating with the Sun frame of reference in the region from 0.3 to 100 AU (but still inside the termination shock). The model equations include the effects of electron heat conduction, Coulomb collisions, photoionization of interstellar hydrogen atoms and their charge exchange with the solar wind protons, turbulence energy generation by pickup protons, and turbulent heating of solar wind protons and electrons. The turbulence transport model is based on the Reynolds decomposition and turbulence phenomenologies that describe the conversion of fluctuation energy into heat due to a turbulent cascade. In addition to using separate energy equations for the solar wind protons and electrons, a significant improvement over our previous work is that the turbulence model now uses an eddy viscosity approximation for the Reynolds stress tensor and the mean turbulent electric field. The approximation allows the turbulence model to account for driving of turbulence by large-scale velocity gradients. Using either a dipole approximation for the solar magnetic field or synoptic solar magnetograms from the Wilcox Solar Observatory for assigning boundary conditions at the coronal base, we apply the model to study the global structure of the solar wind and its three-dimensional properties, including embedded turbulence, heating, and acceleration throughout the heliosphere. The model results are

EDDA: integrated simulation of debris flow erosion, deposition and property changes

Science.gov (United States)

Chen, H. X.; Zhang, L. M.

2014-11-01

Debris flow material properties change during the initiation, transportation and deposition processes, which influences the runout characteristics of the debris flow. A quasi-three-dimensional depth-integrated numerical model, EDDA, is presented in this paper to simulate debris flow erosion, deposition and induced material property changes. The model considers changes in debris flow density, yield stress and dynamic viscosity during the flow process. The yield stress of debris flow mixture is determined at limit equilibrium using the Mohr-Coulomb equation, which is applicable to clear water flow, hyper-concentrated flow and fully developed debris flow. To assure numerical stability and computational efficiency at the same time, a variable time stepping algorithm is developed to solve the governing differential equations. Four numerical tests are conducted to validate the model. The first two tests involve a one-dimensional dam-break water flow and a one-dimensional debris flow with constant properties. The last two tests involve erosion and deposition, and the movement of multi-directional debris flows. The changes in debris flow mass and properties due to either erosion or deposition are shown to affect the runout characteristics significantly. The model is also applied to simulate a large-scale debris flow in Xiaojiagou Ravine to test the performance of the model in catchment-scale simulations. The results suggest that the model estimates well the volume, inundated area, and runout distance of the debris flow. The model is intended for use as a module in a real-time debris flow warning system.

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

Science.gov (United States)

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

2018-02-01

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

Effect of land use land cover change on soil erosion potential in an agricultural watershed.

Science.gov (United States)

Sharma, Arabinda; Tiwari, Kamlesh N; Bhadoria, P B S

2011-02-01

Universal soil loss equation (USLE) was used in conjunction with a geographic information system to determine the influence of land use and land cover change (LUCC) on soil erosion potential of a reservoir catchment during the period 1989 to 2004. Results showed that the mean soil erosion potential of the watershed was increased slightly from 12.11 t ha(-1) year(-1) in the year 1989 to 13.21 t ha(-1) year(-1) in the year 2004. Spatial analysis revealed that the disappearance of forest patches from relatively flat areas, increased in wasteland in steep slope, and intensification of cultivation practice in relatively more erosion-prone soil were the main factors contributing toward the increased soil erosion potential of the watershed during the study period. Results indicated that transition of other land use land cover (LUC) categories to cropland was the most detrimental to watershed in terms of soil loss while forest acted as the most effective barrier to soil loss. A p value of 0.5503 obtained for two-tailed paired t test between the mean erosion potential of microwatersheds in 1989 and 2004 also indicated towards a moderate change in soil erosion potential of the watershed over the studied period. This study revealed that the spatial location of LUC parcels with respect to terrain and associated soil properties should be an important consideration in soil erosion assessment process.

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...

Mesh erosion after abdominal sacrocolpopexy.

Science.gov (United States)

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

1998-12-01

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

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

Science.gov (United States)

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

2017-01-01

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

A flux transfer event observed at the magnetopause by the Equator-S spacecraft and in the ionosphere by the CUTLASS HF radar

Directory of Open Access Journals (Sweden)

D. A. Neudegg

1999-06-01

Full Text Available Observations of a flux transfer event (FTE have been made simultaneously by the Equator-S spacecraft near the dayside magnetopause whilst corresponding transient plasma flows were seen in the near-conjugate polar ionosphere by the CUTLASS Finland HF radar. Prior to the occurrence of the FTE, the magnetometer on the WIND spacecraft ~226 RE upstream of the Earth in the solar wind detected a southward turning of the interplanetary magnetic field (IMF which is estimated to have reached the subsolar magnetopause ~77 min later. Shortly afterwards the Equator-S magnetometer observed a typical bipolar FTE signature in the magnetic field component normal to the magnetopause, just inside the magnetosphere. Almost simultaneously the CUTLASS Finland radar observed a strong transient flow in the F region plasma between 78° and 83° magnetic latitude, near the ionospheric region predicted to map along geomagnetic field lines to the spacecraft. The flow signature (and the data set as a whole is found to be fully consistent with the view that the FTE was formed by a burst of magnetopause reconnection.Key words. Interplanetary physics (ionosphere-magnetosphere interaction · Magnetospheric physics (magnetopause · cusp · and boundary layers; solar wind-magnetosphere interactions

Oxygen isotopic ratios of quartz from wind-erosive soils of southwestern United States in relation to aerosol dust

Energy Technology Data Exchange (ETDEWEB)

Sridhar, K.; Jackson, M.L.; Clayton, R.N.; Gillette, D.A.; Hawley, J.W.

1978-01-01

The oxygen isotopic ratios (expressed as parts per thousand relative to mean ocean water, SMOW, delta/sup 18/O) of the quartz from 13 soils undergoing much wind erosion during the study period of 1972-1975 in four southwestern states and from comparison areas were determined. The delta/sup 18/O for quartz from eight Texas (TX) and Arizona (AZ) soils range from 13.0 to 15.9 /sup 0///sub 00/. The quartz of the sands and silts coarser than 20 ..mu..m from three of the soils had delta/sup 18/O values ranging from 13.1 to 15.1 /sup 0///sub 00/, characteristic of an ultimate igneous-metamorphic origin. The delta/sup 18/O values increase greatly with decreasing particle size of quartz from three soils ranging from loamy fine sand to loam to clay in texture. The delta/sup 18/O of the 1-10 ..mu..m quartz fraction (aerosol size) ranged from 19.2 to 20.2 /sup 0///sub 00/ (19.55 +- 0.28 /sup 0///sub 00/; +- sigma) for the thirteen soils most affected by dust storms. The oxygen isotopic ratios of 1-10 ..mu..m quartz from three Hawaiian soils and two sediments from Lake Waiau occurring at 3,970 m altitude on the Mauna Kea summit on the Island of Hawaii give a delta/sup 18/O mean of 18.3 +- 0.2 /sup 0///sub 00/.

A linear relationship between wave power and erosion determines salt-marsh resilience to violent storms and hurricanes

Science.gov (United States)

Leonardi, Nicoletta; Ganju, Neil K.; Fagherazzi, Sergio

2016-01-01

Salt marsh losses have been documented worldwide because of land use change, wave erosion, and sea-level rise. It is still unclear how resistant salt marshes are to extreme storms and whether they can survive multiple events without collapsing. Based on a large dataset of salt marsh lateral erosion rates collected around the world, here, we determine the general response of salt marsh boundaries to wave action under normal and extreme weather conditions. As wave energy increases, salt marsh response to wind waves remains linear, and there is not a critical threshold in wave energy above which salt marsh erosion drastically accelerates. We apply our general formulation for salt marsh erosion to historical wave climates at eight salt marsh locations affected by hurricanes in the United States. Based on the analysis of two decades of data, we find that violent storms and hurricanes contribute less than 1% to long-term salt marsh erosion rates. In contrast, moderate storms with a return period of 2.5 mo are those causing the most salt marsh deterioration. Therefore, salt marshes seem more susceptible to variations in mean wave energy rather than changes in the extremes. The intrinsic resistance of salt marshes to violent storms and their predictable erosion rates during moderate events should be taken into account by coastal managers in restoration projects and risk management plans.

A linear relationship between wave power and erosion determines salt-marsh resilience to violent storms and hurricanes.

Science.gov (United States)

Leonardi, Nicoletta; Ganju, Neil K; Fagherazzi, Sergio

2016-01-05

Salt marsh losses have been documented worldwide because of land use change, wave erosion, and sea-level rise. It is still unclear how resistant salt marshes are to extreme storms and whether they can survive multiple events without collapsing. Based on a large dataset of salt marsh lateral erosion rates collected around the world, here, we determine the general response of salt marsh boundaries to wave action under normal and extreme weather conditions. As wave energy increases, salt marsh response to wind waves remains linear, and there is not a critical threshold in wave energy above which salt marsh erosion drastically accelerates. We apply our general formulation for salt marsh erosion to historical wave climates at eight salt marsh locations affected by hurricanes in the United States. Based on the analysis of two decades of data, we find that violent storms and hurricanes contribute less than 1% to long-term salt marsh erosion rates. In contrast, moderate storms with a return period of 2.5 mo are those causing the most salt marsh deterioration. Therefore, salt marshes seem more susceptible to variations in mean wave energy rather than changes in the extremes. The intrinsic resistance of salt marshes to violent storms and their predictable erosion rates during moderate events should be taken into account by coastal managers in restoration projects and risk management plans.

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

Directory of Open Access Journals (Sweden)

Gabriela Cristina de Oliveira

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

Application of a ray theory model to the prediction of noise emissions from isolated wind turbines and wind parks

International Nuclear Information System (INIS)

Prospathopoulos, John M.; Voutsinas, Spyros G.

2006-01-01

Various propagation models have been developed to estimate the level of noise near residential areas. Predictions and measurements have proven that proper modelling of the propagation medium is of particular importance. In the present work, calculations are performed using a ray theory methodology. The ray trajectory and transport equations are derived from the linear acoustics equations for a moving medium in three dimensions. Ground and atmospheric absorption, wave refraction and diffraction and atmospheric turbulence are taken into account by introducing appropriate coefficients in the equations. In the case of a wind turbine (W/T) it is assumed that noise is produced by a point source located at the rotor centre. Given the sound power spectrum, the noise spectrum at the receiver is obtained by solving the axisymmetric propagation problem. The procedure consists of (a) finding the eigenrays, (b) calculating the energy losses along the eigenrays and (c) synthesizing the sound pressure level (SPL) by superposing the contributions of the eigenrays. In the case of a wind park the total SPL is calculated by superposing the contributions of all W/Ts. Application is made to five cases of isolated W/Ts in terrains of varying complexity. In flat or even smooth terrain the predictions agree well with the measurements. In complex terrain the predictions can be considered satisfactory, taking into account the assumption of constant wind velocity profile. Application to a wind park shows clearly the influence of the terrain on the wind velocity and consequently on the SPL. (Author)

Vibrational analysis of vertical axis wind turbine blades

Science.gov (United States)

Kapucu, Onur

The goal of this research is to derive a vibration model for a vertical axis wind turbine blade. This model accommodates the affects of varying relative flow angle caused by rotating the blade in the flow field, uses a simple aerodynamic model that assumes constant wind speed and constant rotation rate, and neglects the disturbance of wind due to upstream blade or post. The blade is modeled as elastic Euler-Bernoulli beam under transverse bending and twist deflections. Kinetic and potential energy equations for a rotating blade under deflections are obtained, expressed in terms of assumed modal coordinates and then plugged into Lagrangian equations where the non-conservative forces are the lift and drag forces and moments. An aeroelastic model for lift and drag forces, approximated with third degree polynomials, on the blade are obtained assuming an airfoil under variable angle of attack and airflow magnitudes. A simplified quasi-static airfoil theory is used, in which the lift and drag coefficients are not dependent on the history of the changing angle of attack. Linear terms on the resulting equations of motion will be used to conduct a numerical analysis and simulation, where numeric specifications are modified from the Sandia-17m Darrieus wind turbine by Sandia Laboratories.

Large-scale assessment of soil erosion in Africa: satellites help to jointly account for dynamic rainfall and vegetation cover

Science.gov (United States)

Vrieling, Anton; Hoedjes, Joost C. B.; van der Velde, Marijn

2015-04-01

Efforts to map and monitor soil erosion need to account for the erratic nature of the soil erosion process. Soil erosion by water occurs on sloped terrain when erosive rainfall and consequent surface runoff impact soils that are not well-protected by vegetation or other soil protective measures. Both rainfall erosivity and vegetation cover are highly variable through space and time. Due to data paucity and the relative ease of spatially overlaying geographical data layers into existing models like USLE (Universal Soil Loss Equation), many studies and mapping efforts merely use average annual values for erosivity and vegetation cover as input. We first show that rainfall erosivity can be estimated from satellite precipitation data. We obtained average annual erosivity estimates from 15 yr of 3-hourly TRMM Multi-satellite Precipitation Analysis (TMPA) data (1998-2012) using intensity-erosivity relationships. Our estimates showed a positive correlation (r = 0.84) with long-term annual erosivity values of 37 stations obtained from literature. Using these TMPA erosivity retrievals, we demonstrate the large interannual variability, with maximum annual erosivity often exceeding two to three times the mean value, especially in semi-arid areas. We then calculate erosivity at a 10-daily time-step and combine this with vegetation cover development for selected locations in Africa using NDVI - normalized difference vegetation index - time series from SPOT VEGETATION. Although we do not integrate the data at this point, the joint analysis of both variables stresses the need for joint accounting for erosivity and vegetation cover for large-scale erosion assessment and monitoring.

Erosion problems in Alexandroupolis coastline, North-Eastern Greece

Science.gov (United States)

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

2007-12-01

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

The use of spatial empirical models to estimate soil erosion in arid ecosystems.

Science.gov (United States)

Abdullah, Meshal; Feagin, Rusty; Musawi, Layla

2017-02-01

The central objective of this project was to utilize geographical information systems and remote sensing to compare soil erosion models, including Modified Pacific South-west Inter Agency Committee (MPSIAC), Erosion Potential Method (EPM), and Revised Universal Soil Loss Equation (RUSLE), and to determine their applicability for arid regions such as Kuwait. The northern portion of Umm Nigga, containing both coastal and desert ecosystems, falls within the boundaries of the de-militarized zone (DMZ) adjacent to Iraq and has been fenced off to restrict public access since 1994. Results showed that the MPSIAC and EPM models were similar in spatial distribution of erosion, though the MPSIAC had a more realistic spatial distribution of erosion and presented finer level details. The RUSLE presented unrealistic results. We then predicted the amount of soil loss between coastal and desert areas and fenced and unfenced sites for each model. In the MPSIAC and EPM models, soil loss was different between fenced and unfenced sites at the desert areas, which was higher at the unfenced due to the low vegetation cover. The overall results implied that vegetation cover played an important role in reducing soil erosion and that fencing is much more important in the desert ecosystems to protect against human activities such as overgrazing. We conclude that the MPSIAC model is best for predicting soil erosion for arid regions such as Kuwait. We also recommend the integration of field-based experiments with lab-based spatial analysis and modeling in future research.

Wind reduction patterns around isolated biomass for wind erosion control in a desertified area of Central Sudan