The Spatial-Temporal Insights Into the Water Surface Temperature of the Kannauj-Patna Stretch of the River Ganga: a Remote Sensing Perspective

The water surface temperature is a critical parameter influencing freshwater ecosystems, water quality and riverine dynamics. In the Indian context, no studies have explored the long-term temporal evolution of the Surface temperature of inland water bodies. This study focuses on the Ganga River’s Kannauj-Patna stretch, a significant segment characterized by diverse climatic zones, extensive geographical variability, and substantial anthropogenic activities. Utilizing the LANDSAT satellite archive, a long-term trend analysis (1988-2022) and changepoint detection of water surface temperatures has been conducted. The analysis revealed that the Kannauj-Patna stretch could be divided into three distinct segments based on annual temperature trends: Kannauj to Allahabad (high increase rate, $0.047^{\circ} \mathrm{C} / \mathrm{y}$), Allahabad to Buxar (low increase rate, $0.0278^{\circ} \mathrm{C} / \mathrm{y}$), and Buxar to Patna (mid-high increase rate, $0.042^{\circ} \mathrm{C} / \mathrm{y}$). Further, Seasonal analysis indicated that the pre-monsoon season exhibited the highest temperature increase rate, followed by post-monsoon, winter, and monsoon seasons.