New Delhi:

It is estimated that about a third of China’s urban population is at risk of land subsidence, and researchers say the new findings illustrate a global phenomenon.

The study found that the area of ​​China’s cities below sea level could triple by 2120, potentially affecting 5.5 to 128 million residents.

The research team used satellite data to study 82 cities including Shanghai and Beijing, with a total population of nearly 700 million.

The team, which included researchers from the University of East Anglia in the UK, found that 45% of the urban land area analyzed was sinking, with 16% sinking at a rate of 10mm per year.

Hotspots include Beijing and the coastal city of Tianjin, they said.

The study estimates that 270 million urban residents could be affected, with nearly 70 million experiencing rapid subsidence of 10 millimeters or more per year. The findings were published in the journal Science.

Research results show that land subsidence is mainly caused by urban human activities and will also exacerbate climate change and sea level rise, thereby having a special impact on coastal cities including Tianjin.

Subsidence is thought to be caused primarily by groundwater pumping that lowers the water table, as well as geology and the weight of buildings.

Researchers combined subsidence with sea level rise in their analysis and found that the area of ​​China’s cities below sea level could triple by 2120, potentially affecting 5.5 to 128 million residents. Without a strong social response, it could have been catastrophic, they said.

Shanghai, China’s largest city, has sunk 3 meters over the past century.

The researchers say that while it is important to continuously measure land subsidence, models that predict subsidence should take all factors into account, including human activity and climate change.

They note that not considering land sinking now in adaptation and recovery plans could risk damage to life and infrastructure in the coming decades.

(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)