Assessment of soil erosion susceptibility in a Himalayan river basin using geospatial data and multi-criteria decision analysis

Soil erosion is a significant environmental issue in the Himalayan region, driven by steep terrain, dynamic climatic conditions, and increasing anthropogenic pressures. This study assesses soil erosion susceptibility in the Bhagirathi River Basin, Indian Himalaya, by integrating geospatial techniques with Multi-Criteria Decision Analysis (MCDA). The erosion susceptibility assessment is performed at the sub-watershed level with selected suitable morphometric parameters. The Analytical Hierarchy Process (AHP) assigned weights to these parameters based on expert judgment. At the same time, the Technique for Order Preference by Similarity to the Ideal Solution (TOPSIS) ranked 100 sub-watersheds according to erosion susceptibility. Results reveal that over 35% of the basin area faces a moderate to high risk of soil erosion and sediment deposition, with several sub-watersheds, such as SW 100 (Pi = 0.63), SW 87, SW 77, SW 91, SW 62, and SW 13 (Pi = 0.54 − 0.59), emerging as high-priority zones warranting immediate intervention. In contrast, sub-watersheds like SW 53 (Pi = 0.27) exhibit relatively lower susceptibility, suggesting less urgent but continued monitoring. The integrated AHP–TOPSIS approach demonstrates a robust, GIS-based framework for sub-watershed prioritization, offering clear, quantitative guidance for sustainable watershed management, soil conservation, and sediment control strategies. Additionally, the study aligns with key Sustainable Development Goals (SDGs): SDG 2 (sustainable food production), SDG 3 (environmental protection for health and well-being), SDG 13 (climate action), and SDG 15 (land restoration). By linking erosion susceptibility mapping with global sustainability targets, the findings contribute to climate-resilient catchment management and effective land restoration in fragile mountain ecosystems. This research underscores the transformative potential of geospatial innovations for informed decision-making and sustainable water resource management in complex riverine and catchment systems.