Digital elevation model (DEM) coupled with geographic information system (GIS): an approach towards erosion modeling of Gumara watershed, Ethiopia

This study describes efforts to identify erosion-prone areas in the Gumara watershed using digital elevation model (DEM) data coupled with geographic information system (GIS). The software used to perform the overall analysis were the ESRI ArcGIS v10.3.1 with the ESRI Spatial Analyst and ArcHydro extension. All thematic layers (viz., slope, stream power index, drainage frequency, drainage density, drainage texture, relative relief, plan curvature, profile curvature) were integrated and analyzed in a GIS. A numeric evaluation scale from 1 to 4 was selected for ranking the subclasses of themes. The higher value, 4, represents higher impacts, while the lower value, 1, represents the lowest impact. About 21.71% of the total watershed area is under severe erosion zone. While 32.13%, 23.75%, and 22.42% of the total watershed area falls in moderate, low, and very low erosion zones respectively. In this paper, the numerical classification scheme presented constitutes an integrated approach that shows how to leverage basic watershed information to demarcate erosion prospective zones and measures at various scales for the purposes of watershed management.