BEIJING, July 17 (Xinhuanet) -- As Shanghai's skyline continues to climb, efforts to stop the seaside city from sinking are working. This month, officials have become the first in the world to issue tough new laws to restrict too much ground water from being used. Without them, the city’s foundations could have been jeopardised.
This is Shanghai’s “Tomorrow Square” building – or the claw. It towers 285 metres into the air. But it should be even higher. The ground in the district it’s built on has sunk 2.9 metres, in 90 years.
Over the past century Shanghai’s famous art-deco buildings have sunk to below sea level. It’s meant this wall that we’re standing on had to be built to protect them. Without it, during a high tide, they’d be flooded, and all of that history, destroyed.
But it’s history, that’s to blame. In the 1920s and 30s – these old factories relied on water. They took it from underground aquifers – but took too much.
It left underground air pockets, and the dirt sunk. This micro-model shows the shift.
Wang Hanmei, Shanghai Institute of Geological Survey, said, “Historically speaking, the main reason for Shanghai sinking is underground water extraction. Now though, the city enforces strict rules to make sure there’s enough water underground to stop any shifts.
The Shanghai Institute of Geological Survey says the problems are over. To make sure -- 220 GPS and 37 ground monitors watch for any shifts.
3 city bureaus control water usage in line with new laws. If aquifers start to dry up, water is pumped back underground.
The Institute also monitors metro tunnels – advising on how new work should proceed safely, and where new lines should be built.
It also works with the developers to ensure foundations under construction sites are sturdy.
Progress has meant the city now only moves a few millimetres every year. Normal, for a coastal city with muddy soil.
Wang said, “Shanghai’s subsidence is generally uneven so we mainly focus on its influence on some key infrastructure projects. The current millimetre scope of ground movement will not affect people’s daily lives or the safety of the city.”
A changing skyline on safe ground.
(Source: CNTV.cn)
