Shanghai plans dam on Huangpu By Zhang Yong (China Daily) Updated: 2004-02-09 09:57
Officials in Shanghai are considering the construction of a dam on the
Huangpu River to prevent potential flooding that the coastal metropolis faces
owing to rising sea levels and subsiding land, government and expert sources
said.
"The draft scheme is generally set and has been filed to the Ministry of
Water Resources for approval," Shen Guoping, director of the Research Centre
under Shanghai Urban Planning and Design Research Institute, told China Daily.
"Its main function is to prevent the downtown areas from being inundated with
floods."
The dam, dubbed as Shanghai's "Three Gorges Project," will be located at the
lower reaches of the Huangpu River in the northern Baoshan District, according
to the draft plan.
"Such a dam will help Shanghai's urban area ultimately avoid any possible
flooding," said Shanghai Water Resources Bureau chief engineer Chen Meifa.
To build a dam as a long-term solution is more advantageous compared with the
proposal of further building up existing flood walls along the Huangpu River,
Chen said in a recent work report.
The project is estimated to cost around 2 billion yuan (US$241.8 million) and
take five to seven years to complete, according to Chen's report.
Shanghai has been very cautious about flooding from the Huangpu, which winds
its way through the city from south to north with essential functions such as
supplying water and transporting goods and services.
The city has completed 318 kilometres of flood walls along the river.
But the height of the flood walls has to increase constantly due to the
rising water levels of the waterway, which rose by between 200 and 300
millimetres in the 1990s, according to water authorities.
Higher sea levels on Shanghai's coast and land subsidence are regarded by
experts as the main causes for the river's rising water levels.
Shanghai's sea levels rose 20 millimetres between 2000 and 2003, ranking
second among major Chinese coastal cities only after Tianjin which witnessed a
rise of 25 millimetres, according to the 2003 Bulletin on Sea Levels issued by
the State Oceanic Administration earlier this month.
The rise totals over 60 millimetres since the late 1970s, according to the
bulletin.
Meanwhile, parts of Shanghai's land have been continuously subsiding.
In 2002, the city sank 10.22 millimetres on average and from 1990 to 2001,
Shanghai subsided at an average annual rate of around 16 millimetres.
Today's flood walls along the Huangpu River have been built to 6.9 metres on
average, compared with 4.8 metres in the late 1980s, to ensure good resistance
against the largest flood in 200 years.
"The flood walls cannot grow any more... they may cause serious damage to the
splendid scenery along the Huangpu River," Shen said.
As well, more potential risks may arise in case the water levels of the
Huangpu River get any higher, according to Shen.
However, opposition to the dam project does exist.
Some experts believe that too many artificial modifications may have negative
effects for the environment along the Huangpu River, and break the ecological
balance which has been formed naturally over thousands of years.
Shanghai built a small floodgate on its Suzhou Creek, a branch of the Huangpu
River, in the late 1980s as a trial project.
The gate has functioned well over the past decade,
successfully holding back a number of major floods in the
1990s.
