Land subsidence in China

 

The new research highlights a significant problem facing China's major cities: land subsidence. Due to human activities such as excessive groundwater extraction and the growing weight of urban infrastructure, nearly half of China's urban areas are experiencing land sinking at rates faster than 3 millimeters per year. This affects approximately 270 million people, with 67 million living on land subsiding even faster, at rates exceeding 10 millimeters per year.

The primary cause of subsidence is the extensive extraction of groundwater, exacerbated by climate change-induced droughts. This lowers the water table, causing the overlying land to sink. Additionally, the weight of urban structures contributes to soil compaction, further exacerbating the sinking.

While China is not alone in facing this issue—coastal cities worldwide are experiencing similar problems—the combination of land subsidence and rising sea levels poses a particularly severe risk to China's coastal areas. Roughly a quarter of China's coasts are projected to be lower than sea level, making them highly vulnerable to flooding and other coastal hazards.

Some coastal areas in China have implemented physical protections, such as massive dike systems in cities like Shanghai, to mitigate the risk of inundation. Additionally, the Chinese government has implemented measures to control groundwater pumping and has undertaken projects to transfer water from the Yangtze River to mitigate water shortages and prevent further land subsidence.

While these efforts are commendable, ongoing monitoring and maintenance of infrastructure, as well as continued regulation of groundwater extraction, will be necessary to address the persistent issue of land subsidence in China's major cities.