Overview
- Using 2015–2023 satellite radar, researchers mapped subsidence across New Delhi, Mumbai, Chennai, Kolkata, and Bengaluru, analyzing roughly 13 million buildings housing nearly 80 million people.
- The study identifies 878 square kilometers of sinking urban land with about 1.9 million residents exposed to ground-loss rates greater than 4 millimeters per year.
- An estimated 2,406 buildings in Delhi, Mumbai, and Chennai already face high structural damage risk, which could exceed 23,000 buildings at very high risk within 50 years if current trends continue.
- Excessive groundwater withdrawal is identified as the primary driver, with urban loading contributing, increasing vulnerability through weakened foundations, damaged utilities, and heightened flood and earthquake risks.
- Measured hotspots include Delhi-NCR with rates up to roughly 51 millimeters per year, with additional severe zones in Chennai and Mumbai, while Delhi-NCR shows the highest susceptibility to differential settlement–related building damage risk.