Soil erosion response to future climate variability and best management practices in the Kesinga catchment, India

Abstract Soil erosion poses a growing threat to watershed sustainability under changing climatic conditions, particularly in monsoon-dominated regions. This study integrates the Soil and Water Assessment Tool (SWAT) with bias-corrected CORDEX–South Asia climate projections to quantify present and future sediment yield and to evaluate the effectiveness of structural best management practices (BMPs) in the Kesinga catchment, eastern India. The watershed was delineated into 33 sub-catchments, and model calibration and validation (2003–2020) demonstrated very good performance for streamflow during calibration (NSE = 0.86) and good performance during validation (NSE = 0.72). Sediment-yield performance was satisfactory during calibration (NSE = 0.52) but unsatisfactory during validation (NSE = 0.49), according to the performance criteria adopted in this study. Future projections under RCP4.5 and RCP8.5 scenarios indicate increases in streamflow (26–73%) and sediment yield (5–36%), with the greatest amplification under end-century RCP8.5 conditions; these sediment projections should be interpreted in light of the unsatisfactory validation performance. Spatial analysis revealed persistent sediment hotspots in central and eastern sub-catchments, where high slope gradients and projected precipitation intensification interact to enhance erosion risk. Across the future periods and scenarios, 40.2–51.2% of the catchment area was projected to fall within the severe-to-extreme erosion categories, with the highest proportion occurring under end-century RCP8.5. Structural BMPs, including grassed waterways (GWW) and vegetative filter strips (VFS), were implemented in priority sub-catchments. Under historical conditions, VFS and GWW reduced soil loss by 13% and 25%, respectively, while their combined application achieved up to 38% reduction. Although absolute sediment loads increased under future climates, combined BMP implementation consistently mitigated erosion by 27–36%, demonstrating potential for reducing sediment losses under intensified rainfall regimes. By explicitly linking projected climatic changes with sediment response and BMP performance at the sub-catchment scale, this study provides a spatially targeted framework for climate-resilient watershed management in monsoon-driven agro-ecosystems. The results highlight the need for proactive and spatially targeted implementation of integrated soil and water conservation measures in erosion-prone sub-catchments.