Identifying Soil Erosion Hotspot Area Using GIS and MCDA Techniques, Case Study of Dengora and Meno Watersheds in Belesa Woredas, Amhara Region

Abstract

In Ethiopia soil erosion and land degradation has become a key issue, because of roughed and steep slope topography that soil erosion become accelerating. The main objective of this study was to identify soil erosion hotspot areas in Dengora and Meno watersheds using Revised Universal Soil Loss Equation (RUSLE) and Multi Criteria Decision Analysis (MCDA) techniques. To achieve such objective RUSLE model was used to estimate potential soil losses by utilizing information on Soil, land use/cover, topography, and climatic data. MCDA technique considered land use, soil type, topographic wetness index, stream power index and potential location of gullies. The factors were weighted using pair-wise comparison matrix and weights were combined using Weighted Overlay. Based on RUSLE model, the average annual soil loss of Dengora and Meno watersheds were reaches up to 223.97and 256.09-ton ha-1yr-1 respectively. In Dengora watershed 70.4%, 18.7%, 10.74% and 0.14% and Meno watershed 76%, 16.54%, 7.3% and 0.14% of the total watershed area slightly, moderately, highly and very highly sensitive to soil erosion respectively. On the other hand, GIS based MCDA technique reveals that in Dengora watershed 9.7%, 64.5%, 18% and 7.8% and Meno watershed 6.1%, 71.3%, 23.23% and 0.375% of the total watershed area was highly, moderately, slightly and currently not sensitive to soil erosion respectively. Based on validation, field level observation, MCDA model prediction was more accurate than RUSLE. Both of the watersheds were at moderate risk. Bottomlands of the watersheds under were highly sensitive areas for erosion. Therefore, immediate attention for soil and water conservation practices.