Spatial modeling of erosion hotspots using GIS-RUSLE interface in Omo-Gibe river basin, Southern Ethiopia: implication for soil and water conservation planning

Abstract

Soil degradation due to soil erosion is one of the major environmental threats in developing countries. In resource limited conditions, computing the spatial distribution of soil erosion risk has become an essential and practical mechanism to implement soil conservation measures. This study aimed to assess the spatial distribution of soil loss in Omo-Gibe river basin using the integration of computer-based RUSLE and ArcGIS 10.7.1 to identify areas that require erosion prevention priority. Once raster layer of the input parameters was created, overlay analysis was carried to assess the spatial distribution of soil loss. The estimated annual soil loss varies from 0–279 t ha −1  yr −1 with a mean annual soil loss of 69 t ha −1  yr −1 . The empirical analysis also confirmed that the basin losses a total of about 89.6 Mt of soil annually. Out of the total area; 7% was in very sever class, 4.8% was found in the sever and 8.7% was categorized in very high range. The remaining area were ranging from low to high erosion risk class. The influence of the combined LS factor for soil loss is significant. It was observed that small area of the Omo-Gibe basin contributed for the significant amount of soil loss. The finding of this study is in a good agreement with previous studies. Compared to the country permissible soil loss rate, 26% of the entire basin significantly exceeds the country threshold value (TSL = 18 t ha −1  yr −1 ). As a result, precedence and immediate attention should be given to those erosion prone areas. The study output could deliver watershed management experts and policy makers for better management implementation and resource allocation based on the local context.