Hydroelectricity- not all good!

When a river runs through more than one country a problem occurs with its usage. The Mekong is one example of this.

This article appeared in The Telegraph Wednesday 02 January 2013

China halts £20bn dam project

China has suspended a £20bn hydropower project because of environmental concerns, in a sign of the growing power of the country's green lobby.

Dachaoshan dam in the Yunnan province, China Photo: AP
By Malcolm Moore in Shanghai
10:59AM BST 12 Jun 2009

The Chinese ministry of Environmental Protection said it would not approve any further dams on the Jinsha river in the southern province of Yunnan.
The ministry reacted furiously after discovering that China's two largest power companies, Huadian and Huaneng, had started work on two hydroelectric dams in January without permission.
The two companies, which generate around a fifth of China's electricity between them, were planning to spend 200 billion yuan (£20bn) on eight dams along the Jinsha, which turns into the Yangtze river as it flows into Sichuan.
The project is a similar size to the Three Gorges Dam project. A statement on the ministry's website said both companies had breached the law and that it would not issue any permits to either of them for any new project.
A spokesman for the ministry said the construction of the two dams without proper designs and environmental protection measures would damage the ecology of the river and hurt the local communities.
"The hydropower resources along the Jinsha River are already being over exploited, which will damage the ecological security in the region," said Ma Jun, director of the Institute of Public and Environmental Affairs. He added that Jinsha has some of China's rarest fish species.
The suspension of the project, at a time when the Chinese government has reversed environmental regulations in order to stimulate the economy and stave off job losses, is an important victory for the green lobby.
The government has now also publicly admitted grave problems with the Three Gorges dam. Wen Jiabao, the prime minister, said solving the environmental issues created by the giant dam should be a "priority".
Mr Wen has also blocked the construction of dams on the Nu river in Yunnan, one of only two rivers in China that has not been dammed.
At the Three Gorges, a group of senior government officials said there could be a "huge disaster" with spreading algae, poor-quality water and soil erosion, which has triggered landslides. Another four million people have now been evacuated from the area.

Chinese dams blamed for Mekong's bizarre flow

• From NewScientist 16:35 25 March 2004 by Fred Pearce

Giant Chinese dams on the headwaters of the mighty Mekong River in southeast Asia are being blamed for sudden bizarre fluctuations in the flow of the river in recent weeks. The river is the region's largest and many millions of people rely on its flow.
The Mekong River Commission (MRC), an inter-governmental body that China has refused to join, called an emergency meeting on Wednesday to discuss the crisis on the river. Afterwards it sent an official letter to China demanding information about the operation of its dams, which blockade the main stream of the river.
The 4500-kilometre-long river has seen record low flows since January and strange and unprecedented fluctuations in levels. China has built two large hydroelectric dams on the river: the Manwan and Dachaoshan.
"There is an assumption that the two dams are the cause of the situation," said Surachai Sasisuwan, director of the MRC's water resources department.

The last time the Mekong saw exceptionally low flows was in 1993, during the filling of the Manwan dam. The even larger Dachaosan dam completed in 2003 could be the cause of the new low levels.
Two more dams are currently under construction, while at least another four are at the planning stage. China is also blasting rapids along the river.
"Since the dams began operating, river levels have gone up and down much faster," the MRC's Hans Guttman told New Scientist in a recent interview. While only a fifth of the river's annual flow comes from China, the proportion normally reaches between 50 and 70 per cent in the dry season, he said.
The recent low flows come after a poor monsoon flood season in 2003. The annual monsoon flood is vital to one of the world's biggest freshwater fisheries. Cambodians alone catch two million tonnes of fish a year from the Mekong.
Engineers say the river has huge potential for developing hydroelectric power. But biologists argue it is the absence of dams that until now has preserved the floods and hence the fisheries.

Most of the fish reproduce in forests in central Cambodia. These flood every year when the Tonle Sap, a tributary of the Mekong, is swamped by the main channel, reverses direction and backs up into the forests. A nightmare scenario for fisheries would see the Tonle Sap ceasing to reverse its flow.
"The fish catch is miserable - this has been a bad year," Eric Baran at the Phnom Penh office of Worldfish, an international research centre, told New Scientist.
Researchers admit that Chinese dams are not alone in altering the flow of the Mekong. Downstream countries including Laos and Thailand take significant amounts of water for irrigating their rice crops.
But Guttman says: "The Chinese dams are so large, they are changing everything."