Water at risk in India: a review of national diagnostics and adaptation priorities for sea level rise and groundwater stress

Rising sea levels and groundwater depletion are increasingly recognized as interconnected dimensions of climate change, with significant implications for coastal water security, agricultural sustainability, and food systems. Satellite altimetry observations indicate that global mean sea level has been rising at an accelerating rate since the early 1990s, driven primarily by ocean thermal expansion and increasing mass loss from glaciers and ice sheets, with a smaller yet policy-relevant contribution from changes in terrestrial water storage, including groundwater depletion. The combined effects of declining groundwater levels and rising sea levels reduce the hydraulic resistance of coastal aquifers to seawater intrusion, while elevated sea levels increase baseline flood heights and the frequency of compound flooding events. These interacting processes intensify risks to water quality, agricultural productivity, and coastal livelihoods; particularly in low-lying and deltaic regions. This review synthesizes global and India-focused literature to examine how groundwater extraction, depletion, and contamination interact with climate-driven coastal processes to influence water and food security, with particular emphasis on India’s coastal and deltaic aquifers. The novelty of this synthesis lies in explicitly linking groundwater related physical processes with India’s national coastal risk assessment frameworks including the Coastal Vulnerability Index, Multi-Hazard Vulnerability Mapping, and the Hazard Line within a diagnostics-to-operations framework. However, the review identifies priority adaptation pathways, including managed aquifer recharge, regulation of overexploited aquifers, demand-side efficiency improvements, and the integration of groundwater considerations into coastal planning and early-warning systems.