‘Big dam enhances risks of natural disasters’

China’s land watchdog has asked local authorities to strengthen efforts in monitoring potential geological disasters in the Three Gorges Dam region.

Until June 10, the Three Gorges Dam plans to increase water discharges up to 12,000 cubic meter per second (about 3,000 cu m per second more than water flowing in), which enhances the risks of landslides and bank collapses, China National Radio quoted Guan Fengjun, director of the department of geological environment under the Ministry of Land and Resources, as saying on Wednesday.

“The sudden increase of water discharges from the dam will crash the bank, making the shores unstable,” Guan said.

Experience shows newly built reservoirs face intensified landslides, shore collapses and flooding in the first three to five years after operation, and the Three Gorges Dam is no exception.

Since May, the dam has gradually increased water discharges to relieve a severe drought in central and eastern parts of the country, raising the record-low water level of the downstream lakes, irrigating farmlands and meeting the demand for water.

As of Friday, nearly 1.6 billion cu m of water has been discharged from the dam to the lower reaches, which has raised the water level of the downstream rivers by more than 2 meters since May 4, according to statistics from the Office of State Flood Control and Drought Relief Headquarters.

A statement from the State Council released in mid-May, said urgent problems, such as ecological protection, water transport and geological disaster prevention must be solved and vowed to establish a disaster alert system.

Since the start of the dam’s operation in 2003, extreme weather such as flooding and droughts, as well as geological disasters, have been frequent in the region and many blame the dam.

A report on the protection and development of the Yangtze River in 2007 said the dam speeds up water evaporation, decreasing the water volume downstream.

The report said slight earthquakes have become frequent after the dam began operation, and about 4,719 bank collapses and landslides were detected from 2003 to 2007.

Ma Jun, director of the Institute of Public and Environmental Affairs, said the large dam greatly changes the natural situation, threatening downstream biodiversity and water transport.

But Wang Hai, director of the transport division of the Three Gorges Corporation, told China Daily on Wednesday the worries are groundless.

“The volume of water is still far less than the natural water level from the upper Yangtze River before the construction of the dam,” Wang said, so damage from water would be reduced.

Chang Xiaolin, a professor at Wuhan University, said the water capacity of the Three Gorges Dam is very small compared to the volume of water flowing in the Yangtze River and would have a limited impact.

The dam has cost more than 180 billion yuan ($27.6 billion) and forced the relocation of 1.3 million people to make way for the reservoir.

By By Wang Qian (China Daily), in EcoDebate, 30/06/2011

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