2024-04-20 11:04:17
Nearly half of China‘s major cities are sinking due to water pumping and the increasing weight of rapidly expanding urban areas. Some cities are sinking very fast – one in six at a rate faster than one centimeter a year, researchers quoted by BBC News said.
Scientists said that due to rapid urbanization in recent decades, China is now using much more water for human needs. This most populous country in the world has been struggling with land subsidence for a long time. Both Shanghai and Tianjin showed signs of decline as early as the 1920s. Shanghai has sunk by more than three meters over the past century.
To understand the extent of the problem, a team of researchers from several Chinese universities examined 82 cities, including all with more than two million inhabitants. They used data from Sentinel-1 satellites to measure vertical soil movements across the country.
Looking at the period from 2015 to 2022, the team found that 45 percent of urban areas are shrinking by more than three millimeters per year. About 16 percent is falling faster than ten millimeters per year, which scientists call a rapid rate. 67 million people live in these rapidly sinking areas.
The extent of subsidence is influenced by a number of factors, including geology and the weight of buildings. However, according to the authors, the main element is the depletion of groundwater. This basically means taking water under or near cities for the needs of local residents. The same problem has already been noted in several large urban areas around the world, including the American Houston, the capital of Mexico and the Indian capital of Delhi.