Three Gorges Dam Faces Test As Biggest Floods Since 1954 Approach - Guardian

[hatrack]

China's Three Gorges dam faces its biggest test this week as rain storms threaten to swell upstream water levels beyond those that preceded the Yangtze's last devastating flood in 1998. Flood control is one of the major objectives of the 16m tonne concrete barrier, which was pushed through by the government despite concerns about the environmental and social impact.

Torrential downpours, which have claimed at least 146 lives since the start of the month, have created the most serious challenge since the world's biggest hydropower plant was completed two years ago. "The levels of this flooding will be higher than the historic floods of 1954 and 1998," Wei Shanzhong, the head of the flood control and drought administration office for the Yangtze river, told China Central TV. According to the state media, the rain this week will increase the peak flow in the reservoir to around 70,000 cubic metres per second, considerably higher than the 50,000 figure recorded in 1998, when floods killed more than 4,000 people while the dam was still under construction.

To ease the strain downstream, the dam will close its navigation locks during the peak flow period, diverting the pressure to the giant upstream reservoir. In preparation for the deluge this week, hydroengineers have been sluicing water out of the reservoir at an accelerated rate to make space for the expected downpour.

They believe there is little risk that this reservoir will be stretched beyond its capacity because the peak flow is expected to taper off more rapidly than in 1998. But if the rains exceed forecasts, the dam – and its supporters – will come under unprecedented pressure. Earlier this year, site engineers acknowledged that landslides and water pollution in the reservoir were more severe than anticipated, prompting calls for drastic remedial efforts. They recommended the relocation of a further 300,000 people - in addition to the 1.2 million who have already been forced to leave their homes - to create an "eco-buffer" belt in the worst affected areas.

EDIT

http://www.guardian.co.uk/environment/2010/jul/19/three-gorges-dam-flood-test

[mahatmakanejeeves]

1. "peak flow in the reservoir to around 70,000 cubic metres per second"

Wow. Give that some thought. I hope they weren't using a counterfeit copy of AutoCAD that they bought off the Internet in response to a spam email they received.

[HillbillyBob]

2. now that is a scary thought

Im glad we bought on a hilltop..if it floods here the world has way big problems.

[XemaSab]

3. That's 630,000 CFS!!!!

:o

[mahatmakanejeeves]

4. It's more than that.

One meter = 39.37 inches, so one meter = 3.28 feet. 3.28 feet cubed = 35.3 cubic feet. 35.3 cubic feet per cubic meter times 70,000 cubic meters per second = 2.47 million cubic feet per second.

That's a lot of water.