# Shanghai is Sinking



## hkskyline (Sep 13, 2002)

*Shanghai sinking 5-7mm annually *
7 August 2007
China Daily - Hong Kong Edition

Many parts of the mainland are sinking because of rapid urbanization and heavy use of underground water, a study conducted by the Chinese University of Hong Kong found. 

Researchers projected that coastal cities like Shanghai subsided by 5 to 7 millimeters each year and would become unsuitable for human living in 100 years. 

The university's Institute of Space and Earth Information Science found that urbanization had created immense pressure on the ecology and human living environment in China. 

The urbanization rate in Dongguan city has increased from 13 percent in 1979 to 51 percent in 2000. Shenzhen is housing more than 10 million people on its less than 2,000 square kilometers of land, with an annual population growth rate of 15 percent from 1990 to 2000. 

The trend created surging demands for housing, infrastructure and energy, the study said. 

The institute assistant professor, Zhang Yuanzhi said urbanization would result in the constructing of surfaces which were impervious to water on the ground, such as asphalt and concrete roads. Increased prevalence of impervious surfaces would lead to a higher pressure in drainage and flood prevention of the cities, especially during heavy rains. 

Underground water was also pumped away to fulfill the higher demand for drinking water, Zhang said. Combined with the effect caused by impervious surfaces, land subsidence would result. 

Zhang said some 50,000 square kilometers of lands in 96 cities of the nation were subsiding. About 80 percent of these subsided lands were along the eastern seaboard. The situation was more serious in the Yangtze River Delta and the Bohai-Tianjin Region. 

Underground water in some cities, such as Datong in Shanxi province, was pumped away for use in power plants. Mining in Luoyang also contributed to the problem. 

"It is projected that the land subsidence is ranged from 5 to 10 millimeters a year. That figure superficially appears insignificant. But serious problem will result in a longer period," Zhang said, adding that some cities would not be suitable for human activities after the land subsidence. 

The impervious surfaces also replaced the vegetated lands, making it more difficult for heat to be dispersed by plants. 

The heat island effect would be more serious, Zhang said.


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## irutavias (Jul 15, 2007)

100 years is a long time...I'm sure global warming will get us by then...


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## Vanman (May 19, 2004)

I heard about this a couple of years ago. At that time it was said that Shanghai would limit the amount of high rise development that could occur in the city. Clearly they have done the opposite. I guess very few people see this as an immediate concern, and only time will tell in the end if it is or not.


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## ihilaryduff (Aug 13, 2007)

really ??


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## oliver999 (Aug 4, 2006)

Vanman said:


> I heard about this a couple of years ago. At that time it was said that Shanghai would limit the amount of high rise development that could occur in the city. Clearly they have done the opposite. I guess very few people see this as an immediate concern, and only time will tell in the end if it is or not.


shanghai has limit highrises, if not so, there will be more highrises there.


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## hkskyline (Sep 13, 2002)

*Shanghai sinking, but not as quickly as last year *
22 September 2005

SHANGHAI, Sept 22 (AFP) - China's largest and most populated city Shanghai, built on the marshy banks of the Huangpu river, is slowly sinking, though at a slower rate than before, a report said Thursday. 

The modern metropolis is home to nearly 17 million people and although over exploitation of underground water is the main cause, its 3,000 high-rises built on soft, wet ground have contributed to the problem of subsidence, experts said. 

The eastern port sunk 8.7 millimeters (0.34 inches) last year, more than the target rate of five millimeters a year hoped for by 2010, the Shanghai Daily reported, citing a geological survey. 

The subsidence rate in 2003 was 10.4 millimeters, down slightly from 11.1 millimeters in 2002. If Shanghai continued to sink at 10 millimetres per year it would reach sea level in 40 years. 

To counteract the problem, underground water must be pumped out a rate of 865 million tonnes annually, the figure recorded last year, the report said. 

Then, in a counterintuitive move, some of that water must be pumped back in. 

Subsidence is most clearly seen in Puxi district's Nanpu Bridge and the Lujiazui financial district in Pudong, which is littered with new skyscrapers. 

"Once any increase in subsidence is observed, we will suggest the government take actions such as further controlling the pumping of underground water," said Yu Junying, a senior engineer with the Shanghai Institute of Geological Survey. 

Researchers calculate the rate of subsidence by hammering two tubes underground and observing the distance each moves. 

There are currently more than 100 buildings towering above 100 metres (330 feet) in the eastern city, including the 88-story Jinmao Tower, China's tallest.


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## hkskyline (Sep 13, 2002)

*Shanghai Claims Progress In Fighting Subsidence *
6 February 2007

SHANGHAI (AP)--Shanghai says it is fighting a winning battle in trying to keep the city from sinking. 

The rate of subsidence for the city of 20 million last year was 7.5 millimeters, or about one-third of an inch, the slowest rate since 2000, the state-run newspaper Shanghai Daily reported Tuesday, citing the Shanghai Engineering Administration. 

The city reduced use of underground water by 20% last year, compared with the year before, the report said without giving specific figures. Instead the city is using increasing amounts of river water and pumping water back into depleted aquifers. 

Shanghai was built on marshland along the Yangtze River delta, with an elevation of only four meters above sea level. 

In the 1960s, the city was sinking more than 10 centimeters a year. At that rate, parts of the city would have been flooded by 1999, it said. 

Overall subsidence in 2000 was 12.3 millimeters, the report said. City officials hope to reduce it to 7 millimeters a year by 2010, it quoted Liu Shouqi, an official with the city's land subsidence department, as saying. 

It said the city was installing subsidence and leakage monitors inside the many subway tunnels now under construction to keep track of the problem.


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## Sentient Seas (Feb 17, 2007)

That's horrible. But atleast they are making highrises and supertalls. I guess once the land sinks, they could populate the top of the buildings. 

It seems a very serious problem though, on a more serious note, I really hope something can be done about this.


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## EricIsHim (Jun 16, 2003)

Sentient Seas said:


> That's horrible. But atleast they are making highrises and supertalls. I guess once the land sinks, they could populate the top of the buildings.
> 
> It seems a very serious problem though, on a more serious note, I really hope something can be done about this.


Structurally, highrises and supertalls may not have a big problems as they usually sit on bedrock. But all the entrance and driveway will need to adjust with the new ground level.

The bigger problem is the lowrise that spread all over Shanghai which their foundation doesn't necessarily sit on bedrock but certain depth into the ground.
When the ground sinks, it's harming those building and may collapse eventually. 

It will be a long term problem for Shanghai.


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## hkskyline (Sep 13, 2002)

Yes, it's going to be annoying fixing the buckled pavements. Hope the subway tunnels won't be affected.


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## Max the Swede (Jan 5, 2005)

Interesting


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## PresidentBjork (Apr 29, 2007)

hkskyline said:


> *
> 
> The city reduced use of underground water by 20% last year, compared with the year before, the report said without giving specific figures. Instead the city is using increasing amounts of river water and pumping water back into depleted aquifers.
> 
> *


*

Better not pump any polluted river water into the aquifers, that would make them basically useless. 

hno: But sometimes you get the feeling that if it's not one problem it's the other.

I remember reading about this a few years ago, it's obviously good that the rate of subsidence is falling. If only it can be fully stopped the city will only have to worry about rising sea levels. 
What a 'relief.'*


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## samsonyuen (Sep 23, 2003)

Are there any other major cities sinking?


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## LMCA1990 (Jun 18, 2005)

not a good idea to continuing to build a city on sinking land.


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## Pax Sinica (Dec 10, 2005)

Shang-hai

shang = above
hai = sea


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## DrT (Jun 24, 2005)

samsonyuen said:


> Are there any other major cities sinking?


Yes, New Orleans and Venice come to mind.


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## dhuwman (Oct 6, 2005)

What..? in the skybar section i saw japan sinking and now it's shanhai?
what next?


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## kenworth (Jun 20, 2006)

Sentient Seas said:


> That's horrible. But atleast they are making highrises and supertalls. I guess once the land sinks, they could populate the top of the buildings.
> 
> It seems a very serious problem though, on a more serious note, I really hope something can be done about this.




So what if you building high rise ,if your all roads and sidewalks will be under the wather.?!hno: :lol:


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## kenworth (Jun 20, 2006)

i mean water :lol: :bash:


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## irutavias (Jul 15, 2007)

It would be nice to have an Eastern Venice. =)
But when you think about it, global warming causes rise in sea level. In that way, Every city that is on the coastline is at risk for 'sinking'


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## hkskyline (Sep 13, 2002)

Sinking is not the same as flooding though. If the water level rises, then the land itself isn't sinking.


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## ioaz10 (Jul 7, 2007)

funny
knowing this.. people will compensate for the change by adding concrete, etc..


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## z0rg (Jan 17, 2003)

Venice has been sinking for centuries and nothing has happened. Many, many cities and areas around the world are supposed to be "sinking". I see this issue a little sensationalist, and a good source of propaganda for skyscraperphobes, but nothing to be really worried about.

Btw, it's quite logical that the terrain settles due to the urban boom. It is not supposed to be a constant tendence, just a phase. Same happened in New York, and any other city I guess.


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## big-dog (Mar 11, 2007)

I heard this issue is under control. The sinking speed in Pudong has been reduced from 10mm to 5mm per year. The most useful solutioin is to reduce the consumption of underground water from that area.


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