Assessment of Soil Erosion Risk Area Using Object Based Image Analysis and RUSLE3D Model: A Case Study of Wenberta Watershed, Atsbi-Wenberta Woreda, Tigray, Ethiopia
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Date
2016-06
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Addis Ababa Universty
Abstract
Soil erosion is a global issue that threatens human livelihoods and civilization. The impact of soil erosion can be worst in the developing countries like Ethiopia, including Tigray Highlands, which is highly affected by the risk of desertification that is also aggravates by a combination of natural and human factors. In most areas of the country farmers are highly dependent on natural land proprieties and unable to improve soil fertility through application of purchased inputs. Therefore, the community try to protect the soil loss of the area to tackle such kind of problems. In this study, Revised Universal Soil Loss Equation (RUSLE) 3D model was used to quantify the erosion in a GIS environment in order to calculates actual average soil loss in Wenberta watershed, Tigray region, Ethiopia. RUSLE 3D model applied to produce the soil erosion risk map using ArcGIS10.3, SAGA GIS, and eCognition Essential software's. The model incorporates Rainfall , Soil, Topographic (a three dimensional modification), Land cover, and Practice Management factors. Land Cover map of the area was produced using Object Based Image Analysis (OBIA) from a very high resolution (0.25 cm spatial resolution) of aerial photographs for the entire watershed. The overall accuracy of land cover from OBIA was 85.2%. Slope and Upslope area were generated from a 10 m resolution Digital Elevation Model (DEM). The model final result shows that the actual soil loss quantity ranges from 0 to very high soil loss rates ( 127.92 t/ha/y). According to the final result the central parts of watershed have very high severity of soil erosion and most of the mountainous areas also high soil erosion risks. The study showed that stone bunds and bench terrace in Practice Management are successful management practice to conquer the soil erosion risks of the area. This study demonstrates that the RUSLE 3D model is a robust model for estimation of soil erosion studies and risk assessment mapping integrating with remote sensing products and Geographic Information Systems and can be applied in other parts of Ethiopia. As a result, the areas that have high erosion risk should be conserved in priority by the most known methods of conservation practices of the area.
Key words: RUSLE3D, Soil Erosion, OBIA, GIS, Remote Sensing, Wenberta watershed, SAGA GIS
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Keywords
RUSLE3D, Soil Erosion, OBIA, GIS, Remote Sensing, Wenberta watershed, SAGA GIS