Holistic assessment of India's water security using coupled climate-human intervention models

Water resources planning and quality governance plays a crucial role in socio-economic growth, development, public health, and ensuring food and energy security. However, managing it is increasingly challenging due to the effects of climate change and human interventions. Sub-catchment scale modeling has become a practical approach to addressing these spatial and temporal variations. The InVEST model, developed by the Natural Capital Project, is a reliable solution to estimate water quality and resources as it adopts a robust technique for understanding water security for socio-economic progress. This study attempts to understand water security across four decades by examining dynamic shifts in climate variability. The analysis stratifies India into six major physiographic divisions reflecting variations in physical features, geological structure, and topographic relief, which collectively influence the nation's landscape, climate, and ecosystems. Land use and land cover was categorized to eight categories revealing a decrease in forest, barren land, and snow/glacier areas, while agricultural land, urban areas, wetlands, water bodies, and rangelands showed an increasing trend. Despite these shifts, the percentage of mean rainfall converted to water yield across the decades remained relatively consistent, estimated at 38%, 36%, 33%, and 32% for the years 1985, 1995, 2005, and 2018, respectively. Additionally, it has been observed that potential evapotranspiration has significantly increased spanning across four decades. This trend states that the climate change and human interventions have drastically impacted the potential evapotranspiration across decades but not much significant change has been observed in precipitation. The potential evapotranspiration is the driving factor that contributes to more frequent flooding and drought events. To mitigate these challenges, careful evaluation of urban land use classes is recommended to minimize environmental impacts and hydrological stability.