Why Beijing (and 45 other cities in China) are sinking

Beijing sinking 11 cm: Major Chinese cities are sinking. What lessons do the world's other sinking cities have for China?

A man walks on a bridge in the financial district of Pudong in Shanghai, China in June.

China’s cities are sinking, according to a new scientific study published this month in the journal Remote Sensing.

According to the Chinese government, 46 cities across China are sinking into the ground. In the last decade alone, Beijing has sunk 14 inches. The city continues to sink at a rate of nearly 11 centimeters per year.

The study, conducted by an international team of seven scientists and engineers is based on InSAR radar technology, which monitors land elevation changes.

This sinking phenomenon, called subsidence, has a number of causes. The rapid construction of massive buildings, roads, and other infrastructure projects has put a lot a weight on the ground.

Excessive pumping of groundwater is also a major problem that plagues thirsty urban areas as they struggle to keep up with rising populations and water demand.  Both Shanghai and Beijing have struggled with overtaxed aquifers.

And the sinking soil has an impact on other critical aspects of city infrastructure.

 “We are currently carrying out a detailed analysis of the impacts of subsidence on critical infrastructure (e.g. high-speed railways) in the Beijing plain,” wrote the study’s authors in an email to the Guardian. “Hopefully a paper summarising our findings will come out later this year.”

Beijing is particularly concerned about the impact the subsidence could have on the city’s trains, which transport a large number of the city’s 20 million residents each day. 

There could be hope for Chinese cities, however. Much of the problem is rooted in poor enforcement of groundwater pumping regulations, which offers an obvious area for improvement.

And there are other cities which are exploring potential solutions, including Mexico City, which is sinking even faster than Beijing, at a rate of 28 centimeters per year.

Built on drained lakebeds, Mexico City loses up to 40 percent of its water per year as the water travels through a network of old pipes to water users throughout the city. 

And many of Mexico City’s poorer residents might not even have access to piped water, relying instead on limited daily scheduled deliveries of potable water.

In order to counter its water problems, Mexico City officials are exploring water reuse options, including the treatment and recovery of wastewater, according to a February article published by the Christian Science Monitor.

The city is also looking to a new source for its drinking water – the sky. With so much piped water lost to the ground beneath the city, Mexico City is now exploring rainwater collection and purification to lighten the load on overtaxed aquifers.

Beijing is also exploring waterworks projects to counter one of the main problems behind the city’s subsidence. In 2015, China began to build a network of tunnels and canals to ease up the strain on underground aquifers.

While experts say that they are not yet sure how much of a difference the new canal and tunnel system will make, Beijing is taking steps towards a more regulated system.

Shanghai, too, has switched to river water for daily water use, slowing its own descent. City efforts have slowed Shanghai’s subsidence from up to four inches per year in the 1950s and 60s to 2/5 of an inch per year today. 

The problem is not limited to Mexico and China – dozens of cities worldwide face subsidence each year. And there's a growing recognition among coastal cities that rising sea levels are adding fresh urgency to addressing this issue. But the efforts in Mexico City, Shanghai, and Beijing's indicate that cities can make necessary changes to slow or stop the trend.

You've read  of  free articles. Subscribe to continue.

Dear Reader,

About a year ago, I happened upon this statement about the Monitor in the Harvard Business Review – under the charming heading of “do things that don’t interest you”:

“Many things that end up” being meaningful, writes social scientist Joseph Grenny, “have come from conference workshops, articles, or online videos that began as a chore and ended with an insight. My work in Kenya, for example, was heavily influenced by a Christian Science Monitor article I had forced myself to read 10 years earlier. Sometimes, we call things ‘boring’ simply because they lie outside the box we are currently in.”

If you were to come up with a punchline to a joke about the Monitor, that would probably be it. We’re seen as being global, fair, insightful, and perhaps a bit too earnest. We’re the bran muffin of journalism.

But you know what? We change lives. And I’m going to argue that we change lives precisely because we force open that too-small box that most human beings think they live in.

The Monitor is a peculiar little publication that’s hard for the world to figure out. We’re run by a church, but we’re not only for church members and we’re not about converting people. We’re known as being fair even as the world becomes as polarized as at any time since the newspaper’s founding in 1908.

We have a mission beyond circulation, we want to bridge divides. We’re about kicking down the door of thought everywhere and saying, “You are bigger and more capable than you realize. And we can prove it.”

If you’re looking for bran muffin journalism, you can subscribe to the Monitor for $15. You’ll get the Monitor Weekly magazine, the Monitor Daily email, and unlimited access to CSMonitor.com.