Managing Land Subsidence in Tokyo

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Tokyo, with a population of about 30 million, had a delta where approximately a million people lived. Groundwater pumping in the 1920s led to subsidence of the delta, sinking up to five meters by 1970. To counteract this, Tokyo brought in surface water from reservoirs, banned groundwater pumping, and implemented dikes and pumps to manage the subsidence, leading to the stabilization of the land's sinking.

A study has found that more than two dozen US coastal cities are sinking by more than 2mm a year. It’s a similar picture across the world. Nearly half of China’s major cities, as well as places such as Tehran and Jakarta, are facing similar problems. These issues are compounded by sea level rises caused by global heating. Madeleine Finlay speaks to Prof Manoochehr Shirzaei of Virginia Tech University and Prof Robert Nicholls of the University of East Anglia to find out what’s making our cities sink and whether anything can be done to rescue them from the sea. Help support our independent journalism at theguardian.com/sciencepod