Cities Across the World Sinking from Groundwater Depletion: It Can Be Reversed

Groundwater over-extraction is causing widespread land subsidence in coastal cities, accelerating exposure to sea-level rise. Examples include Jakarta (over 10 cm/yr in places), Tianjin (threatening 15% of the population with inundation by 2120), parts of San Diego, Iranian cities, and coastal New Zealand. Subsidence happens because urban areas sit atop aquifers that help support the ground; pumping deflates this subsurface “balloon,” lowering the surface. Osaka serves as a natural laboratory: heavy pumping from the 1920s-1960s lowered water levels by up to 30 m and produced more than 2 m of sinking. Researchers analyzed records from 44 monitoring wells (to 500 m depth) and millimetre-precision surface measurements using interferometric synthetic aperture radar tied to GNSS stations to track recovery.

The findings show groundwater recovery produces measurable uplift: average land rise across greater Osaka of about 4 mm/yr and local peaks to 12 mm/yr, with groundwater levels climbing up to 1 m/yr; areas with the fastest recharge experienced the fastest uplift. Uplift is spatially patchy, forming narrow corridors that align with known tectonic faults. Faults act as subterranean dams, blocking lateral flow so the “upstream” side regains water and elevation faster than the downstream side. Reducing extraction and allowing aquifers to recover reduces and, in places, reverses subsidence - an actionable strategy to help coastal cities adapt to sea-level rise.