A Geographic Information System Based Soil Loss and Sediment Estimation in Gerdi Watershed, Highlands of Ethiopia

This study was carried out to spatially predict the soil loss rate of Gerdi watershed with a Geographic Information System (GIS) and Remote Sensing (RS). RUSLE adapted to Ethiopian conditions was used to estimate potential soil losses by utilizing information on rainfall erosivity (R) using interpolation of rainfall data, soil erodibility (K) using soil map, vegetation cover (C) using satellite images, topography (LS) using Digital Elevation Model (DEM) and conservation practices (P) using satellite images. Based on the analysis, the total annual soil loss potential of the study watershed was 28,732.5 tons/yr. Out 147.9 ha (64%) of the land’s watershed was categorized none to slight class which under soil loss tolerance (SLT) values ranging from 5 to 11 tons ha-1 yr-1. The study results indicated that the rate of potential soil loss in the watershed ranged from very low to extremely high. The area covered by none to slight potential soil loss was about 147.9 ha (64%) whereas moderate to high soil loss potential covered about 202.1 ha (36%) of the study watershed. The study demonstrates that the RUSLE together with GIS provide a good estimate soil loss rate over areas