Assessment of soil loss rate-Lake Tana basin, Ethiopia

Soil degradation is the main issue of the Lake Tana basin, Ethiopia. Therefore an attempt has been made in this paper to estimate the soil loss rate (ton/hectare/year) using Revised Universal Soil Loss Equation model. Furthermore, thematic maps pertaining to stream power index, slope gradient, planform curvature, profile curvature, and drainage density were overlaid in GIS environment to get the spatially distributed erosion hazard zones of Lake Tana basin. The results showed that soil loss rate of Lake Tana basin ranges from 1 to 27 (t/ha/year). The critical (12 to 27 t/ha/year) erosion zone covers an area of 180,499.42 ha with a total soil loss of 3,519,738.69 tons. Soil loss rate has been found maximum at the highest elevations with the highest erosivity factor values. The total average annual loss of soil is 9,636,059.97 tons which is an issue of concern and demands conservation measures to maintain the agricultural productivity and to avoid the siltation of Tana Lake by soil erosion.