Integrated Remote sensing and GIS-based Universal Soil Loss Equation for Soil Erosion Estimation in the Megech River Catchment, Tana Lake Sub-basin, Northwestern Ethiopia

Abstract

Severe land degradation occurred in northern highlands of Ethiopia due to its complex topography, rainfall, and various anthropogenic activities. Soil erosion in the Megech river catchment, one of the major catchments of Lake Tana sub-basin of the Abbay River basin using Remote sensing, and GIS based Universal Soil Loss Equation (USLE) was quantified. The study was conducted by estimating the important factors that affect soil erosion namely, rainfall erosivity (R), topography (LS), soil erodibility (K), cropping management practice (C), and support practice (P). The results showed that the annual soil loss in the total catchment is 8,43,736 tons with an average soil erosion rate of 41.54±75.92 tons ha-1yr-1 of which the soil loss from the upper catchment is 6,86,705 tons (36.63±64.2 tons ha-1yr-1) while from the lower catchment 1,57,031 tons (32.68±57.41 tons ha-1yr-1). In 3.1% of the total catchment area the soil erosion is extreme with the rate greater than 50 tons ha-1yr-1; in 20.5% of the area it is greater than 10 tons ha-1 yr-1; and in 50.5% of the area it is very low, less than 1 ton ha-1yr-1. Soil erosion rates varied from various land uses in a given topographic condition, and from a particular land use type in different topographic conditions. Soil conservation- neglected post-harvested land is eroded by small rainfall intensities. Substantial soil erosion occurs from degraded lands and decreased vegetative covers. Implementation of scientific measures of land use management, agriculture, and restoration of degraded lands would control soil erosion.