Vertical Land Motion and Human Exposure Across India's Coastal Regions

Abstract In India, over 200 million people live within 100 km of the coastline, and many reside in low‐lying areas exposed to increasing flood risks associated with sea‐level rise. However, the role of vertical land motion (VLM)—particularly land subsidence—in shaping this coastal exposure remains poorly quantified. Here we present the first assessment of VLM across India's coastal zone, using 8 years of Sentinel‐1 Interferometric Synthetic Aperture Radar (InSAR) time series data (2016–2024). This comprehensive data set reveals widespread subsidence with several notable hotspots: Ahmedabad, Chennai, Amaravathi, Kochi, Kakinada, and Kolkata. The five major deltas along the east coast display extensive subsidence up to 20 mm/yr. Over 8.5 million residents live in coastal areas experiencing subsidence greater than 5 mm/yr. Our findings suggest that coastal subsidence in India is more extensive than previously recognized and poses a significant challenge for long‐term land‐use planning in coastal zones.