Millions at risk: Major Chinese cities sinking under their own weight, finds study

A new research reveals that the ground beneath millions in China's major cities is subsiding due to human activities.

This sinking land is worsening the risk of flooding and sea level rise in the country's coastal regions. The study, published on Thursday (April 18) in the journal Science, indicates that nearly half of China's urban areas, which house 29 per centof the population, are sinking at a rate exceeding 3 millimetres (approximately 0.12 inches) per year.

This phenomenon affects around 270 million people residing on sinking land.

Add WION as a Preferred Source

Meanwhile, 67 million people are living on land that is subsiding faster than 10 millimetres (0.4 inches) each year.

China’s extensive groundwater withdrawal is one of the main factors for subsidence, researchers said. Cities have been drawing water from underground aquifers faster than it can be refilled, a situation intensified by climate change-fueled drought. Excessive pumping out of water lowers the water table and causes the overlying land to sink.

The land in China is also sinking due to the growing weight of the cities themselves. Soil can compactnaturally from the weight of sediments building up over time and from heavy buildings pressing down on the ground, causing the land to steadily sink.

Land subsidence is a global threat, not just a regional one. Coastal cities around the world face this challenge, including metropolises like New York in the US.

The Netherlands battles with vast swathes of land sinking below sea level, affecting a quarter of its entire territory. Mexico City holds a grim record, subsiding at an alarming rate of up to 50 centimetres a year – almost 20 inches. The consequences are terrible, especially in coastal regions.

Sinking land coupled with rising sea levels creates a double whammy, exposing more people, property, and land to devastating floods.

The study says roughly a quarter of China’s coasts will be lower than sea level because of subsidence and projected sea level rise, leading the area to colossal damage and putting lives at risk.

According to the study, Tianjin, Shanghai and areas around Guangzhou are significantly exposed to both issues.

(With inputs from agencies)