Soil Erosion, Watershed, RUSLE

As a form of environmental degradation, soil degradation directly or indirectly affects many lives through decreased agricultural yields, increased flooding and habitat loss. Soil loss has been increasing in most parts of the world and is most pronounced in tropical developing countries where there is poor or zero soil and water conservation (SWC) planning and management activities. Identifying areas prone to soil erosion has also been inadequate, having not been informed by dedicated scientific studies. This is true of the poorly understood watershed of Welmel in the Oromia region of Ethiopia, where most livelihoods heavily rely upon agriculture. To plan effective SWC management techniques, a solid knowledge of spatial variations across different climate, land use and soil erosion is essential. This study has aimed at identifying potential areas needing SWC practices through conducting a spatial modeling of soil erosion within the Welmel watershed's Genale Dawa basin using a geographic information system (GIS), remote sensing (RS), multiple factors as land uses and climate. The Welmel catchment is located in southeastern Ethiopia and extends between 5 • 0 0" N-7 • 45 00" N and 39 • 0 0" E-41 • 15 0" E. The revised universal soil loss equation (RUSLE), which was previously adapted to Ethiopian conditions, was used to estimate potential soil loss. It used information on interpolated rainfall erosivity (R), soil erodibility (K), vegetation cover (C) and topography (LS) from a digital elevation model (DEM) and that of conservation practices (P) from satellite images. The study demonstrates that the RUSLE using GIS and RS considering different climates and land management practices provides a great advantage in that it allows one to spatially analyze multilayer data in order to identify soil erosion-prone areas and thereby develop the most appropriate watershed management strategy. The mean soil loss was determined to be 31 tons ha −1 year −1 and it varied between 0 and 169 tons ha −1 year −1. About 79% of the watershed lies within the tolerable level of 11 tons ha −1 year −1. However, the remaining 21% has a high soil truncation trait, mainly due to its steeper slope and use as cultivated land. Our study identifies cultivated and deforested areas of the watershed as the potential SWC practice demanding areas. Thus, the application of RUSEL using GIS across different land management practices and climate zones is a potential tool for identifying SWC demanding sites. This remains helpful in efforts towards sustainable land management practices for the sustainable livelihood of the local human population.

Al-Sen watershed with a surface area of 98.8 km2 is forming an important vital spatial sector for Syrian Coast Basin in the western part of Syria. Soil loss in Al-Sen basin is one of the major growing eco-environmental risks that need to be assessed geographically. Statistical-Spatial evaluation of soil erosion risks is a useful and urgent step for creating soil erosion management plans along with spatial implementation. At present study, a quantitative
assessment of soil erosion on grid basis is carried out using GIS and SPSS technologies. The outcomes illustrate that 43.01% of the study area affected by low erosion of soil, 29.05% moderate erosion, 16.33% high erosion, and 11.85% very high erosion, respectively. Moreover, the major factor accelerating soil loss in the study basin was LS factor of RUSLE (r2=0.74). This study, however, has also suggested two statistical models of the soil erosion case in an Al-Sen basin. The results of this study are very important for local decision-makers in establishing spatial conservation strategies.

The study integrated the Revised Universal Soil Loss Equation (RUSLE) with Geographic Information System (GIS) to quantify the potential soil erosion risk in the Fincha'a watershed. Rainfall, soil, digital elevation model (DEM) and satellite image data sets were used as inputs in order to generate RUSLE factor values. The potential annual soil loss of the study area ranged from nil at plain surfaces to 223.12 t ha yr at steep 1 1 slopes of the farmland. The mean annual soil loss rate of the study area was 33.66 t ha yr. We obtained 1 1 the highest mean annual soil loss of 38.8 t ha yr for farmland. However, the smallest annual soil loss of 1 1 4.3 t ha yr was obtained from the forestland. Nearly 36.2% of the total farmland was classified under high 1 1 soil erosion risk while only 2.4 and 11.7% were categorized under high soil erosion risk for the forestland and grassland, respectively. The study revealed that the farmland was highly vulnerable to erosion than other land use and land cover types. In conclusion, information on average annual soil loss is important for selecting appropriate conservation measures to reduce on-site soil loss and their off-site effects.

Soil erosion by water is recognised as a worldwide land degradation issue, particularly in arid and semi-arid regions. The aim of this study is to apply the powerful capabilities of advanced remote sensing and geographic information system techniques to identify the areas at risk to water erosion. This study presents the assessment of water erosion in mountainous areas (eastern Aures, Algeria) based on three main factors: the friability of the bedrock, degree of slope and density of vegetation cover. Alsat1 image was used to produce land use and vegetation (NDVI) maps. Digital elevation model was used in constructing the slope gradient map. The erosion risk map was obtained by the combination of indices assigned to thematic layers following multicriteria decision rules. Water erosion was generally not concerning in the eastern Aures (slight risk = 33 %, moderate risk = 44 % of the area). This simple–qualitative approach gave good results for assessing soil erosion equally to quantitative methods since 89.55 % of field verifications were accurate. The non-alarming state and the low rate of severe and extremely severe risk to erosion are due to (1) the low steep slopes, (2) the good quality of vegetation (forests with thick undergrowth), and which are occurring on (3) resistant materials of the substratum, and (4) the low human pressure. Results of this study, which may be conducted with reasonable costs and accuracy over large areas, are of significant help in prioritising areas in decision making and sustainable planning.

Aquí se estima la pérdida natural de suelos por erosión hídrica en la Alta Cuenca del río Escoipe- Chicoana, que resulta ser un tipo de erosión lenta. En vistas de que parte del área actualmente está sujeta a un proyecto de Declaración de Paisaje Protegido, es que surge este trabajo porque, posiblemente, los suelos de la zona se vean afectados si, una vez concretada la iniciativa, se verifica un incremento (no planificado) de la actual tasa de visitas. Para la estimación de A (A ACTUAL) se recurrió a la Ecuación Universal de Pérdida de Suelo (RUSLE) mediante la creación y ejecución de un Sistema de Información Geográfica (SIG). Se trabajó sobre una superficie de 31424,00 hectáreas, obteniéndose que aproximadamente el 85 % de la zona presenta serios problemas de pérdida de suelo y que, de mantenerse en el tiempo, alcanzaría los 5 centímetros de espesor de suelo al cabo de 100 años, cuando para la formación de igual altura de suelo son necesarios aproximadamente 400 años. Ello, es preocupante y nos indica que algo muy serio está sucediendo. Después de analizar varias posibilidades y sin descartarlas, se concluye que se ha de buscar respuestas en el pastoreo a campo abierto de los animales domesticados. Se recomienda establecer pautas sustentables de manejo pecuario en toda la zona.
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En este trabajo se estimó la pérdida de suelos actual de campos de cultivos establecidos en un territorio serrano ubicado en el centro de la provincia de Salta, Argentina, en la Alta Cuenca del río Escoipe- Chicoana, de jurisdicción del municipio de Chicoana. Los cálculos que intervienen en la Ecuación Universal de Pérdida de Suelo Revisada (RUSLE) se llevaron a cabo a través de la creación y calibración de un Sistema de Información Geográfica (SIG) para la superficie agrícola de 697,85 has del área. Se obtuvo que el 65,69 % de los campos agrícolas (458,40 has) presentan pérdidas de suelo superiores a 10 Mg/ha/año, lo cual, era de esperar, pues, en la zona no se realizan otras prácticas agronómicas más que las tendientes a mantener la mayor cantidad de la superficie cultivada cubierta durante el año, especialmente, en la época estival. Se recomienda tomar medidas correctivas, pues ya no hay lugar para realizar mitigaciones. Éstas, consistentes en planificar y ejecutar actividades en el terreno tendientes a disminuir el valor final de los factores Largo y Porcentaje de la Pendiente (LS) y, se advierte, que modificar los valores actuales de los factores Prácticas de Cultivo (P) y Cobertura (C), ciertamente representará una ardua tarea.
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Soil aggregate stability is a key indicator of soil quality. Changes in aggregate stability may serve as early indicators of recovery or degradation of soils. We have applied laboratory based aggregate fractions method where fine and coarse soil aggregates fixed by set of sieves for two types of soil to estimate aggregate stability. Co-efficient of vulnerability and mean weight diameter was calculated for each aggregate size fractions. Stability index (SI) and aggregate size distribution was determined to conclude on soil erodibility and compaction. Mean weighted diameter (MWD) of the Nurkerke and Hesteert soil after wet sieving is 2.03 mm and 1.56 mm respectively. The instability index of the Nurkerke soil is 2.41 and of Hesteert soil is 2.89.  The aggregate stability index of the Nukerke is 0.41 and Hesteert soil is 0.35. The coefficient of vulnerability (Kv) of Nukerke soil is 2.18 while the Hesteert has 2.81; hence the Nukerke soil seems more stable than the Hesteert soil of Belgium. Results revealed that the Nukerke soil is less vulnerable for erodibility and compaction than the Hesteert soil under investigation.

Soil erodability that correlated with barren or void vegetation cover land has an outlandish result in the lower part of the study area. This study aim to analysis the soil erosion risk of G Madugula Mandal, Visakhapatnam district. The study combines both remote sensing and GIS techniques to obtain severe erosion risk zones in the study area by taking into consideration of ancillary data such as Soil, DEM and LandSat satellite data. The method verified and cross checked by ground truth data. The results show that, Very Low and Low classes are scattered in all over the study area due to the randomization of the Land units and represent almost 76.14% of the study area. The Very Low class is occupying 50.67% of the study area in correspondence to valley fills or foot slopes, where the low slope gradient allows the accumulation of materials transported by water or
Ch. Vasudeva Rao, G. Ashenafi Tolessa, E. Aminnedu- Erosion risk identification
study using RUSLE model in G. Madugula Mandal, Visakhapatnam District,
A.P., India
EUROPEAN ACADEMIC RESEARCH - Vol. II, Issue 9 / December 2014
12247
gravity. The High class is mainly concentrated in the Kumbidisingi Panchiteat at Solamulu and in a small unit in Solabham Panchiteat Mallipadu village representing 17.36% of the study area. Therefore, appropriate soil conservation measure should be taking place in order to further prevent soil loss.