Archive · 19 Jan 2026
India's River Deltas Sinking Rapidly, Study Reveals
A new study shows that many river deltas around the world, including several in India, are sinking faster than the sea is rising.
This is happening because people are taking too much groundwater, building dams, and expanding cities.
The study looked at 40 deltas and found that more than half are sinking more than 3 millimeters every year.
Some deltas, like the Brahmani and Mahanadi in India, are sinking even faster, which means they are at higher risk of flooding and losing land.
These deltas are home to many people and important cities, so this is a big problem that needs to be fixed.
India's major river deltas, including Ganga-Brahmaputra, Brahmani, Mahanadi, Godavari, Kaveri, and Kabani, are sinking at an accelerated rate.
Land subsidence is often a bigger contributor to local relative sea-level change than climate-related sea level rise.
The study analyzed satellite data from 2014 to 2023 across 40 deltas worldwide using interferometric synthetic aperture radar (InSAR).
Human activities such as groundwater extraction, sediment supply alteration due to dams, and urban expansion are major drivers of land sinking.
Brahmani and Mahanadi deltas are among the fastest-sinking, with large portions of land sinking faster than 5 millimetres per year.
- Who
- Researchers from Nature conducted the study.
- What
- India's major river deltas are sinking at an accelerated rate due to groundwater extraction and rising sea levels.
- When
- The study analyzed data between 2014 and 2023.
- Where
- The study focused on 40 river deltas worldwide, including several in India such as the Ganga-Brahmaputra, Brahmani, Mahanadi, Godavari, Kaveri, and Kabani deltas.
- Why
- Human activities such as groundwater extraction, sediment supply alteration due to dams, and urban expansion are contributing to the sinking of river deltas.
- Study Title
- Global subsidence of river deltas
- Number of Deltas Studied
- 40
- Key Indian Deltas Affected
- Ganga-Brahmaputra, Brahmani, Mahanadi, Godavari, Kaveri, Kabani
- Average Subsidence Rate in Half of Deltas
- Over 3 millimetres per year
- Subsidence Rate in 13 Deltas
- Faster than global sea-level rise (approximately 4 millimetres per year)
- Subsidence Rate in Brahmani and Mahanadi Deltas
- Faster than 5 millimetres per year
- Population Supported by Deltas
- Between 4 and 6 per cent of the world’s population (350-500 million people)
- Megacities in Deltas
- 10 of the world’s 34 megacities