Comparison of Measured and Derived Topographic Factor Values for Soil Loss Estimation

Abstract

One of the inputs for the Revised Universal Soil Loss Equation (RUSLE) is the topographic factors specifically slope gradient and length derived from Digital Elevation Model (DEM). However, the accuracy of the derived data was not estimated. Therefore, this study was conducted in Quashay watershed, Northwestern Ethiopia to compare the topographic factor of slope length and gradient derived from Advanced Space-borne Thermal Emission and Reflection Radiometer (ASTER) DEM with measured value for soil loss estimation. DEM data were downloaded from reliable sources and other slope length and gradient data were measured from the field. Statistical Product and Services Solutions version 20 was used to analyze measured and derived values. The result shows no significant difference between measured and derived slope length and gradient (p>0.05).Therefore, I conclude that the topographic data derived from ASTER DEM can be used as an input for soil loss estimation.

Keywords: ASTERDEM, Slope length and gradient, soil loss, RUSLE, Ethiopia.