Application of Geospatial Technologies and AHP Technique in the Identification of Soil Erosion-Prone Zones in the Rift Valley, Southern Ethiopia

Soil erosion is causing significant environmental problems in many world regions, including the present study area Sile River watershed, which is located in the Southern Ethiopian Rift Valley. Consequently, land becomes degraded, biodiversity declines, and agricultural production decreases. Identification of susceptible soil erosion zones is highly needed to develop effective soil erosion management and conservation plans. The present study mainly aimed to use geospatial technologies and the analytical hierarchy process (AHP) technique to prioritize soil erosion-prone zones. There are nine significant soil erosion-controlling parameters were selected, such as drainage density (DD), slope, elevation, topographic wetness index (TWI), curvature, precipitation, soil type, land-use/land cover (LULC), and normalized difference vegetation index (NDVI). These selected thematic layers were mapped by utilizing optical and digital elevation satellite images, field observations, secondary data, GIS, and remote sensing tools. By adopting analytical hierarchy process (AHP) calculation methods, the weights of the selected thematic layers and their respective subthemes have been computed. After calculating the final weights of the selected thematic layers, the weighted linear combination method (WLC) was adopted to identify the areas prone to soil erosion. The final results show that 63.11 sqkm (27.56%), 115.33 sqkm (50.36%), and 50.57 sqkm (22.08%) of the study area is prone to low, medium, and high soil erosion-prone zones, respectively. An area under curve (AUC) is a statistical method used to assess the soil erosion model’s accuracy. In this study, 60 soil erosion hotspots were located in high-resolution Google Earth images, and the same was used for the AUC calculation. Regarding AUC, the model performed well with a value of 0.719 (71.9%). The soil erosion assessment carried out in this study has provided satisfactory results. The outcome of this research has an important inference for planners and policymakers, as they can utilize this information to develop and implement appropriate water and soil conservation strategies within the Sile River.