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
viii
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. Based on RUSLE model, the average annual soil loss of Dengora and Meno watersheds were reaches up to 223.97 and 256.09 ton ha-1yr-1 respectively. In the Dengora watershed 70.4%, 18.7%, 10.74% and 0.14% of the total watershed area predicted soil loss ranges between 0 to 15, 15 to 50, and 50 to 200 and above 200 ton ha-1respectively. In Meno watershed 76%, 16.54%, 7.3% and 0.14% of the total watershed area predicted soil loss ranges between 0 to 15, 15 to 50, 50 to 200 and above 200 ton ha-1respectively. On the other hand, the GIS based MCDA technique considered five major factors 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 Tool of ArcGIS Spatial Analyst Toolbox to obtain the final erosion hotspot map. In Dengora watershed 9.7%, 64.5%, 18% and 7.8% of the total watershed area was highly, moderately, slightly and currently not sensitive to soil erosion respectively. In 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. Thus, bottomlands of the watersheds under highly sensitive areas for erosion therefore immediate attention for soil and water conservation practice. Therefore, both tools should be applied for planning and targeting of watershed intervention.