Assessment of Water Dynamics and Water Quality Parameters over Gobind Sagar Reservoir, India, Based on High-Resolution Remote Sensing Approach

Monitoring surface water dynamics and ensuring water quality parameters are important for the health of the environment and sustainable economic development with irrigation planning for various crops and drinking purposes in drought situations. Satellite data in conjunction with open-source APIs like Google Earth Engine (GEE) offers multiple observations to effectively monitor both surface water dynamics and water quality. The Normalized Difference Water Index (NDWI) was applied to differentiate water pixels from non-water pixels. Landsat series data were analyzed to assess the surface water dynamics, viz. water occurrence, absolute change water occurrence, water recurrence, water seasonality, and water transition of Gobind Sagar Reservoir during period from 1984 to 2019. The majority of the reservoir contains permanent water, and there is minimal overall change. This study also used Sentinel-2 multispectral data to monitor changes in optically active water quality parameters for pre- and post-monsoon seasons during period from 2016 to 2021. A semi-analytical inversion method was applied to compute optically active water quality parameters including chlorophyll-a concentration (Chl-a) concentrations ranging from 0 to 39.3 mg/m and total suspended matter (TSM) ranging from 0 to 149.78 g/m³. Variations in water quality parameters are linked with climatic factors such as rainfall and high runoff. Intense rainfall strongly occurred during the monsoon season that delivers higher loads of suspended materials and dissolved solids into the river, and consequently, these materials reduce the penetration of light. Monitoring water dynamics and water quality parameter serves as a crucial indicator for assessing the productivity and eutrophication of the river water system.