The most worrying finding is that about a third of China’s population, or 270 million people, live on land that is sinking faster than 3mm per year. Of these, 67 million live in areas that are sinking rapidly, at a rate of more than 10mm per year.

The research, published in the journal Science by a team of scientists from Chinese and American universities, used satellite data to map city subsidence on a national scale from 2015 to 2022.

Subsidence is particularly severe in coastal cities such as Tianjin and Beijing. The risk of flooding from rising sea levels combined with land subsidence is increasing, threatening the safety and lives of tens of millions of people.

The main causes of subsidence are identified as excessive groundwater extraction and the weight of buildings. Groundwater extraction reduces soil saturation, leading to subsidence. Meanwhile, the weight of high-rise buildings also contributes to increasing pressure on the ground.

The study recommends strict control of groundwater extraction and appropriate urban planning to minimize land subsidence. Collaboration between the government, the research community and civil engineers is essential to effectively address this issue.

Thu Giang (according to SCMP)