2024-04-19 09:47:00
Shanghai is one of the cities most exposed to the effects of land subsidence and expected sea level rise./AFP/Getty Images
2024.04.19 Fri published 6:47 p.m. JST
（ＣＮＮ） According to a study published on the 18th in the American academic journal Science, nearly half of China’s urban areas, where 270 million people live, or 29% of the country’s population, are sinking by at least 3 millimeters per year. .
67 million people live on land that is sinking more than 10 mm each year.
Researchers say widespread groundwater pumping in China is one of the main reasons for land subsidence. Cities pump water from underground aquifers at a faster rate than groundwater can accumulate. This situation is becoming even more serious due to droughts caused by climate change. Excessive pumping lowers the water table and causes the land above it to sink.
The earth is also sinking due to the increased weight of the city itself. Due to the weight of earth and sand accumulated over the years and the collapse of heavy buildings, the ground naturally compresses and gradually sags.
Land subsidence is not just a problem in China. Dozens of coastal cities in the United States, including New York, are sinking. In the Netherlands, 25% of the country has sunk and is now below sea level. Mexico City is believed to be experiencing the fastest land subsidence in the world, with land subsidence of up to 50 centimeters per year.
Along the coast, the effects of land subsidence are more severe and sea levels are rising, exposing more land, people and property to destructive flooding.
As sea levels rise and coastlines sink, large areas of land risk being exposed to devastating floods/Tingshu Wang/Reuters
The study suggests that regarding a quarter of China’s coastline will lie below sea level due to land subsidence and predicted sea level rise, causing significant damage and putting human lives at risk. hazard. The areas surrounding Tianjin, Shanghai and Guangzhou are exposed to both problems.
Sea walls have already been built in some coastal regions of China to physically protect areas from increased risk of flooding. Researchers say the city of Shanghai, for example, built embankments several meters high.
“A huge coastal levee system like this significantly reduces the risk of flooding, even when accounting for both land subsidence and sea level rise,” the researchers told CNN .
He said the Chinese government had used several methods to combat land subsidence in recent years, including enforcing strict laws regulating groundwater pumping. In and around Shanghai, the rate of land subsidence has been slowed by limiting groundwater pumping.
1713541991
#million #people #China #live #shrinking #cities #study #finds #CNN.co.jp
