Integrative Application of USLE and GIS for Modeling Soil Erosion Dynamics and Conservation Prioritization in the Poboya Watershed, Indonesia

Land-cover change driven by agricultural expansion, mining activities, and forest conversion is a major cause of declining hydrological function in watershed ecosystems. The loss of vegetation accelerates soil erosion, sedimentation, and ecological instability. This study aims to model and quantify soil erosion rates across land units in the Poboya Watershed by integrating the Universal Soil Loss Equation (USLE) with Geographic Information Systems (GIS). Analytical units were generated through an overlay of slope, soil type, and land-use maps, and subsequently validated through field surveys. The USLE factors (R, K, LS, C, and P) were derived from climate data, laboratory soil analyses, a Digital Elevation Model (DEM), vegetation indices, and observations of conservation practices. The results indicate that 56% of the Poboya Watershed area falls within the very low to low erosion classes; however, 33% of the area exhibits moderate to very severe erosion, particularly in zones with steep slopes, highly erodible soils, and areas affected by mining and dryland agriculture. These conditions highlight the presence of erosion hotspots that may accelerate downstream sedimentation and intensify land degradation. The findings underscore the need for critical-land rehabilitation, enhanced vegetative and mechanical conservation measures on steep slopes, and forest protection to sustain the watershed’s ecological functions.