Cities worldwide are sinking at alarming rates, but that doesn’t mean the ground is sinking at the same rate everywhere. Some neighbourhoods may be far more affected than others close by, with serious consequences for their residents.

Land subsidence – the gradual sinking of the ground surface – is a global urban problem. Rapid development often drives excessive groundwater extraction, which can cause underground sediments to compact and the land above to sink. The risk of flooding is exacerbated by rising sea levels and more intense rainfall associated with climate change.

One recent study estimated that about 71% of the global coastal population lives in subsiding regions, many of which are densely populated and already threatened by sea-level rise.

Advances in satellite monitoring now allow researchers to measure subsidence across cities at fine spatial scales. In a new study in Nature Cities a team of Chinese scientists used nine years of these satellite images to assess 465 large cities worldwide. They found cities in Asia are subsiding fastest, and that cities in developing countries are generally sinking faster than those in wealthier countries.

But citywide patterns........

© The Conversation