Monitoring Surface Water Dynamics and Assessing the Impact of Watershed Management Using Sentinel-2 Imagery and GIS: A Case Study of Shahapur Watershed, Maharashtra, India

Water resources in semi-arid regions are highly sensitive to climatic variability, land-use changes and watershed management interventions. The present study monitors surface-water dynamics and assesses the impact of watershed management interventions in the Shahapur Watershed, Maharashtra, India, using Sentinel-2 multispectral imagery and Geographic Information System (GIS) techniques. Sentinel-2 satellite data were used to derive the Modified Normalized Difference Water Index (MNDWI) for the identification and spatial delineation of surface-water bodies. Multi-temporal imagery was analyzed to quantify changes in water extent using different MNDWI threshold values. The results indicate a substantial increase in mapped surface-water extent between 2018 and 2021. In 2018, approximately 0.04 ha of surface water was detected, whereas in 2021 the estimated water extent ranged from 2.51 to 2.87 ha depending on the applied MNDWI threshold. The corresponding increase in water pixels demonstrates a marked expansion of surface-water availability during the postintervention period. GIS-based spatial analysis further facilitates the assessment of the distribution and extent of water resources within the watershed. The observed changes suggest that watershed management measures may have contributed to improved water retention and surface-water availability; however, variations in rainfall and seasonal hydrological conditions must also be considered when attributing changes exclusively to management interventions. The study demonstrates the effectiveness of Sentinel-2 imagery, MNDWI, and GIS for monitoring surface-water dynamics and evaluating watershed-scale environmental changes. The approach provides a cost-effective and spatially explicit framework for supporting watershed planning, resource management and sustainable water-resource development in Maharashtra