24 Apr 2024

Beyond Joshimath: 6.7 Crore Chinese Residents Also Dwell in Rapidly Sinking Regions

Subsidence or sinking of land isn't just limited to Joshimath and some other Himalayan cities; it's affecting over half of China's major urban centers as well.

In certain locales, land is sinking at an alarming pace, with approximately one in every six cities in China sinking by approximately 10 millimeters annually.

Scientists attribute this phenomenon to groundwater depletion and the escalating strain on swiftly expanding urban areas.

In the last few decades, large-scale landslides have been seen in many rapidly expanding cities in the country.

Researchers examined 82 cities

To understand how rapidly this problem is growing, a team of researchers from several universities in China examined 82 cities with a population of more than 20 lakh.

In the data from 2015 to 2022, it was seen that in 45 percent of the urban areas, the height above sea level is decreasing by three mm every year.

Whereas in 16 percent urban areas this decline was happening by more than 10 mm per year.

6.7 crore people in China are living in rapidly sinking areas

According to scientists, this speed was quite fast. How serious this situation is can be gauged from the fact that 6.7 crore people in China are living in areas which are rapidly sinking.

Land subsidence is caused by many factors, including geology and the weight of buildings. However, according to researchers, the main reason for land subsidence in China is extraction of groundwater.

The surge in urbanization across China in recent decades has led to heightened groundwater extraction in certain regions, as outlined by researchers.

Some areas of Beijing are sinking by as much as four inches (11 cm) each year, due to the over-pumping of groundwater from beneath China's capital, a survey has revealed. Beijing has a population of over 2 crore and is the fifth most water-stressed city in the world, meaning the resulting subsidence is set to worsen.

Groundwater has sat beneath the city for thousands of years, but it is increasingly being used for domestic consumption, industrial use and agriculture. Beijing alone requires 3.5 billion litres of water each year, two-thirds of which is pumped from beneath the city. As it is removed, the soil compacts, causing subsidence above. The process is accelerated by the increasing weight bearing down as buildings continue to be constructed.

Land is sinking and sea level is rising

Whereas due to rising water level in coastal cities, millions of people are at risk of floods.

By 2020, approximately six percent of China's landmass was lying slightly above sea level. Within the next century, this proportion may surge to encompass 26 percent of the nation's territory.

Researchers say that as the sea level rises, the land is sinking rapidly, due to which millions of people will be at risk of floods.

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