Soil erosion estimation using RUSLE modeling to assess priority areas for conservation in the Kandra sub-river basin of Nepal

Reliable estimation of soil erosion is essential for identifying erosion-prone areas and supporting the development of effective soil and water conservation strategies. This study examines decadal changes (2003-2023) in soil erosion by analyzing spatial and temporal variations in soil loss in the Kandra sub-river basin using the Revised Universal Soil Loss Equation (RUSLE) model integrated with a Geographic Information System. The computed annual soil loss values in the basin ranged from 0 to 52.08 t ha⁻¹ yr⁻¹ in 2003, 0 to 61.08 t ha⁻¹ yr⁻¹ in 2013, and 0 to 59.85 t ha⁻¹ yr⁻¹ in 2023. Spatial classification of erosion severity indicates a gradual reduction in areas affected by very severe erosion (>20 t ha⁻¹ yr⁻¹), which declined from 2.34 ha in 2003 to 1.62 ha in 2023. The conservation priority map highlights the northern Siwalik region as the most erosion-prone area due to the combined effects of steep slopes, high rainfall erosivity, and land-cover conditions. Different land rehabilitation programs, conservation agricultural techniques, and bioengineering techniques should be prioritized in the high-risk erosion hotspots. Overall, these findings provide valuable insights for decision-makers in planning and implementing effective basin management strategies to control soil erosion.