Assessment of Soil Erosion Risk in Lake Tana Sub-Basin Using Rusle and Gis, Upper Blue Nile, Ethiopia
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Date
2013-06-06
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Addis Ababa University
Abstract
Land degradation in terms of soil erosion is a major environmental issue posing threat to sustainability livelihood in Tana Sub-Basin. This study attempted to assess soil erosion risk by using Revised Universal Soil Loss Equation and Geographic Information system and delineating deltas formed in the Lake Tana in spatial approach. Knowing extent and severity of the land is important as a decision support system to policy makers, resource managers as well as local communities and farmers. The result of this assessment showed spatial distribution of different soil erosion severity across the area and makes comparative assessment of the watersheds. In addition to this, soil erosion susceptibility was estimated through Revised Universal Soil Loss Equation (RUSLE). This model uses topographic factor, soil factor, rainfall erosivity factor, cover management and support practice factor as an input to map soil erosion risk areas. Satellite image of 1986 and 2011 year are used for the delineation deltas formed in the Lake Tana using PCA change analysis. Specifically, Satellite image of year 2011 is used for the development of Land Use/Land Cover to that is used for the development of Cover management and support practice factor. The research finds that More than 27% of the study area excluding the lake is highly susceptible to erosion risk and nearly 3% is very highly susceptible to erosion. In the same way, 20.77 % of the sub-basin is moderately susceptible to erosion in a range of 50-200t/ha/year. Nearly 50 % of the sub-basin is none to slightly susceptible to erosion. From the analysis of PCA change Gilgel Abbay river formed 588.4 ha delta while Gummera and Ribb rivers formed river delta by 11.91 ha and 14.77 ha respectively.
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Assessment, Soil Erosion Risk, Lake Tana Sub-Basin, Using Rusle, Gis, Upper Blue Nile, Ethiopia