Spatiotemporal analysis and correlation of surface temperature, vegetation cover, and water index using remote sensing and GIS techniques in Ambedkar Nagar, India

Rapid urbanization and land cover changes have significant impacts on vegetation health, water availability, and Land Surface Temperature (LST), yet medium-sized Indian cities remain underexplored in this context. This study aims to investigate the spatiotemporal dynamics of LST, Normalize Difference Vegetation Index (NDVI), and Normalize Difference Water Index (NDWI) changes and analyse their correlation in Ambedkar Nagar city, Uttar Pradesh, India, using multi-temporal Landsat data from 2010 to 2025 and Digital Elevation Model (DEM) data. Landsat 5 TM and Landsat 8 OLI/TIRS imagery were pre-processed using radiometric and atmospheric corrections, and indices were extracted through GIS-based techniques. The results show a clear downward trend in the NDVI, with mean values declining from 0.22 (max 0.52) in 2010 to 0.12 (max 0.41) in 2025. Similarly, the NDWI decreased from 0.22 (max 0.39) in 2010 to 0.12 (max 0.20) in 2025, indicating reduced surface water availability. In contrast, mean LST rose from 30.97 °C (max 40.32 °C) in 2010 to 35.76 °C (max 44.21 °C) in 2025, highlighting intensified urban heat. Moreover, the correlation (R2) analysis showed consistently negative but weak relationships between LST with NDVI & NDWI, suggesting that vegetation and water contribute to cooling but are not the sole drivers of LST variability. These findings highlight that urbanization, agricultural expansion, and industrial activity have intensified surface heating and reduced ecological resilience in Ambedkar Nagar. The study underscores the need for region-specific planning strategies such as urban greening, wetland restoration, and stricter zoning to mitigate rising temperatures and ensure sustainable development.