Sinking cities can rise again when groundwater recovers
When cities stop over-pumping groundwater, the land beneath them rises again, offering coastal cities a path to adapt to rising seas.
Many major cities are sinking as they drain groundwater faster than nature can refill it. Jakarta sinks more than ten centimetres each year.
Tianjin, China, faces drowning 15% of its population by 2120 if the trend continues. Around 80% of New Zealand's urban coast is sinking.
But new research shows the process reverses: when groundwater recovers, so does the land. Osaka is the proof.
Between the 1920s and 1960s, heavy pumping lowered groundwater by up to 30 metres and land by more than two metres in places. The Japanese government introduced strict groundwater regulations in the early 1960s.
Since then, the ground has risen four to 12 millimetres each year as aquifers refilled. The uplift isn't even; the corridors of fastest recovery mapped almost perfectly onto known tectonic fault lines underground that act like dams, directing water flow and shaping where recovery happens fastest.
- more than 10 centimetres each year
- Jakarta sinking rate
- 15%
- Tianjin population at risk by 2120
- around 80%
- New Zealand urban coast sinking
- 4 to 12 millimetres each year
- Osaka groundwater recovery rate
Why it mattersReducing groundwater extraction could reverse coastal land sinking, buying vulnerable cities crucial time to adapt as sea levels rise from climate change.
AustraliaAustralia's coastal cities and areas like Christchurch and Wellington in nearby New Zealand face similar threats; halting over-pumping offers a practical defence against compounding sea-level and subsidence risks.
✓ Claims checked against the source and corrected before publish. checked 2 h ago
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