Overview
- Published Oct. 28 in Nature Sustainability, the analysis used 2015–23 satellite radar to assess subsidence across New Delhi, Mumbai, Chennai, Kolkata and Bengaluru.
- Researchers mapped 878 km² of sinking land with nearly 1.9 million people living in areas subsiding faster than 4 millimetres per year.
- An estimated 2,406 buildings in Delhi, Mumbai and Chennai already face high damage risk, and up to 23,529 across the five cities could reach very high risk within 50 years if current trends continue.
- Maximum observed rates include up to 51 mm/year in New Delhi, 31.7 in Chennai, over 26 in Mumbai, 16.4 in Kolkata and 6.7 in Bengaluru, with hotspots such as Bijwasan, Faridabad and Ghaziabad and localized uplift near Dwarka.
- The study warns that uneven sinking heightens flood and earthquake vulnerabilities and calls for groundwater regulation, resilient design and sustained satellite monitoring.