Study Reveals 270 Million People Residing on Subsiding Land in China's Urban Centers
A recent study unveils that approximately 29% of China's population is located in urban regions experiencing a sinking rate exceeding 3 millimeters annually. The findings indicate a concerning trend of land subsidence in major Chinese cities.
Millions of people in China's major cities are facing the concerning issue of land sinking beneath their feet. This is happening as a result of human activities, and it is increasing the risk of flooding and rising sea levels in the country's coastal areas.
According to a new research study published in the journal Science, nearly half of China's urban areas, which is home to 29% of the country's population, are sinking at a rate faster than 3 millimeters (about 0.12 inches) per year. This means that approximately 270 million people are living on land that is sinking.
67 million people are currently residing on land that is sinking at a rate exceeding 10 millimeters (0.4 inches) per year. This alarming subsidence is mainly attributed to China's excessive extraction of groundwater, according to researchers. The rapid pumping of water from underground aquifers, coupled with climate change-induced drought, has led to a depletion of water sources faster than they can be replenished. As a result, the water table drops, causing the land above to sink.
The land is sinking because cities are getting heavier. This happens when soil compacts under the weight of sediments and buildings, causing the land to slowly sink.
FILE - Yahir Mayoral and Emily Camacho walk amid the rubble of their grandmother's home, destroyed by flooding driven by a sea-level rise in their coastal community of El Bosque, in the state of Tabasco, Mexico, Nov. 30, 2023. Driven by climate change, sea-level rise and increasingly ferocious storms are eroding thousands of miles of Mexico's coastline facing both the Gulf and the Pacific Ocean. (AP Photo/Felix Marquez, File)
Yahir Mayoral and Emily Camacho are walking through the remains of their grandmother's house in El Bosque, Tabasco, Mexico. The house was destroyed by flooding caused by rising sea levels on November 30, 2023. The coastal community is facing the effects of climate change, with sea-level rise and stronger storms eating away at the coastline along the Gulf and Pacific Ocean in Mexico. (AP Photo/Felix Marquez, File)
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Land subsidence is a widespread issue, not limited to just China. In the US, many coastal cities, including New York City, are experiencing sinking land. Similarly, in the Netherlands, a quarter of its lands have sunk below sea levels. Mexico City is also facing rapid land subsidence, with the land sinking up to 50 centimeters (nearly 20 inches) per year.
The impact of land sinking is particularly severe along the coasts, where rising sea levels exacerbate the situation. This puts more land, people, and property at risk of destructive flooding.
Roughly a quarter of China's coastlines are projected to be below sea level due to subsidence and rising sea levels, posing a significant risk of damage and endangering lives. The study highlights Tianjin, Shanghai, and areas near Guangzhou as particularly vulnerable to these threats.
As oceans rise and the coasts sink, vast swaths of land will be exposed to destructive flooding from coastal storms and shoreline erosion.
As oceans rise and the coasts sink, vast swaths of land will be exposed to destructive flooding from coastal storms and shoreline erosion.
Tingshu Wang/Reuters
Some coastal areas in China have already implemented physical protection measures against the risk of inundation. In Shanghai, for instance, Professor Shengli Tao, co-author of a study from Peking University, highlighted the city's impressive dike systems that are meters tall. According to Tao, these massive coastal dike systems significantly lower the risk of inundation, even with factors like land subsidence and sea level rise. He mentioned that he is not aware of any other countries that have constructed such massive dike systems.
Thursday's study, according to Leonard Ohenhen, a doctoral researcher at Virginia Tech, is considered "scientifically robust" and effectively brings attention to the fact that subsidence is not solely a problem in coastal areas. Ohenhen, who recently conducted a study on land subsidence in the US, commended the study for its thorough analysis.
While coastal cities often receive more attention due to sea level rise, Ohenhen emphasizes that land subsidence is a common issue in most urban areas as well. In fact, he notes that the rate of subsidence in urban cities can be comparable to or even higher than that in coastal cities.
Courtesy Sonam Dorje
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The Chinese government is taking steps to address the issue of sinking in various ways. One of these ways is by enforcing strict laws to regulate the pumping of groundwater in recent years. This has helped to reduce the rate of subsidence in Shanghai and its surrounding areas, which used to be a major problem years ago.
In addition to groundwater regulations, China has initiated a project to transfer water from the Yangtze River in the south to areas in the north, including Beijing. This has been especially beneficial for Beijing, which has faced water shortages. The project has successfully prevented excessive groundwater pumping and has effectively halted land subsidence in the capital city, according to a study.
Tao expressed his belief that the Chinese government's initiatives will effectively tackle the problem of land subsidence. He recommended that a continued focus on regulating groundwater extraction in large urban areas and ongoing maintenance of dike systems in coastal regions would be beneficial.
Editor's P/S:
The alarming issue of land sinking in China, affecting nearly half of its urban areas, is a grave concern. With 270 million people residing on land that is sinking at a rate exceeding 3 millimeters annually, and 67 million on land sinking at a rate of more than 10 millimeters per year, the risks are dire. Excessive extraction of groundwater, exacerbated by climate change-induced drought, has caused a depletion of water sources and a drop in the water table, leading to land subsidence. This issue is not unique to China, with many coastal cities worldwide, including New York City, the Netherlands, and Mexico City, experiencing sinking land. The impact is particularly severe in coastal areas, where rising sea levels compound the threat of flooding, putting more lives and property at risk. The Chinese government's efforts to address the situation, such as enforcing regulations on groundwater pumping and implementing a water transfer project from the Yangtze River, are essential steps towards mitigating the risks posed by land subsidence.
