Why is it in the news?
→ Nature study warned India’s major river deltas are sinking at alarming rates.
→ Findings highlight flood and displacement risks for millions.
Category
Geography
Important Points
- The study analysed 40 deltas across 29 countries with 236 million people exposed to near-term flood risk.
- Indian deltas affected: Ganga-Brahmaputra, Brahmani, Mahanadi, Godavari, Cauvery and Kabani.
- Land subsidence exceeds global mean sea-level rise (~4 mm/year).
- Over half of deltas subsided faster than 3 mm/year (2014–2023).
- Brahmani (77%) and Mahanadi (69%) among fastest sinking; many areas >5 mm/year.
- Nearly 50% of deltas subsiding across over 90% of their area.
- Seven deltas account for 57% of global subsiding delta area (~265,000 sq km).
- Major cities like Kolkata, Dhaka, Bangkok and Shanghai are also sinking rapidly.
- Primary cause: unsustainable groundwater extraction.
- Other causes: reduced sediment supply, river regulation, land-use change.
- Indigenous and rural communities below 1 m elevation face highest risk.