Soil Erosion Assessment by RUSLE Model using Remote Sensing and GIS in the Tono River Basin

Abstract

This study assesses soil erosion potential in the Tono River Basin, West Africa, using the Revised Universal Soil Loss Equation (RUSLE) model integrated with Remote Sensing (RS) and Geographic Information Systems (GIS). The analysis incorporates five core factors: rainfall erosivity (R), soil erodibility (K), slope length and steepness (LS), cover management (C), and support practices (P). Rainfall erosivity (R) values range from 9.69 to 15.13 MJ·mm/ha·hr·yr, with higher values concentrated in the northern and northeastern basin, indicating regions more prone to erosive rainfall. Soil erodibility (K) values, calculated based on soil texture and organic matter, reveal Lithosols as the most erosion-susceptible soils, with a maximum K-value of 1.4722 m/ha·h·MJ·mm?¹. Topographic analysis using the LS factor reveals that steeper slopes, particularly in the northwest and southeast of the basin, are more susceptible to erosion, with LS values reaching up to 0.39. The cover management factor (C) indicates that forested areas, due to their dense canopy and extensive root systems, generally exhibit lower C-values compared to croplands, reflecting better soil protection. Similarly, agricultural lands with appropriate vegetation cover can also contribute to reduced erosion risk. Support practice factor (P) mapping highlights spatial and temporal variations in conservation measures, with lower P-values observed in areas where effective erosion control practices are implemented. Mean annual soil loss is estimated at 6,123.38 t·ha?¹·yr?¹, with erosion hotspots near the Tono reservoir and steep, bare-sloped zones. A soil erosion risk map, generated through a weighted overlay of RUSLE factors, categorizes the basin into low, moderate, high, and very high erosion risk zones. This spatial approach offers valuable insights for sustainable land use planning and prioritization of soil conservation efforts in erosion-prone areas of the Tono River Basin.