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'Proposed Lao dam will not impede sediment flows'

Publication Date : 25-07-2012

 

Xayaboury hydropower plant, the first run-of-the-river dam in the lower Mekong basin, will not cause any serious impediment to sediment flows to the lower Mekong delta, according to international consultants.

Poyry and Compagnie Nationale du Rhone, both reputable international dam consultants who are providing consultancy services for the Xayboury dam development project, say sediment from upstream of the planned Xayboury dam contributes only 2.5 per cent of the total sediment flows to the lower Mekong delta.

Sediment flows include nutrient rich top soils washed into the Mekong mainstream during the wet season.

Despite the fact that many common people see it as simply dirt, the soil is an important food source for aquatic animals and plants, and provides fertilising nutrients for farmers who grow cash crops along the river.

Vietnamese and Cambodian environmentalists have expressed concerns that once the power plant is built on the Mekong mainstream, it will prevent the flow of sediment to the Mekong nations downstream, posing a threat to food security for people in the region.

The consultants say that because the Xayboury dam is a run-of-the-river dam which does not store a large amount of water, it will not prevent flows of the sediment downstream as other dams in Mekong territories do.

Despite the fact they say the construction of the dam will not have a strong influence on downstream sediment flows in the Mekong, Poyry and Compagnie Nationale du Rhone recommended the Xayboury dam developers equip the dam with a flushing system, which can ensure effective transportation of sediment and rock.

The dam redesign will force the project developers to spend more than US$100 million in additional funds to construct the extra facilities, aiming to address the worries and concerns of Mekong nations downstream.

A number of dams have been built on the upper Mekong River and these dams do not have the flushing systems, according to Compagnie Nationale du Rhone.

The Lao government has hi red the international dam experts to provide advice on how to build the most modern dam the world, but it is still waiting for comments from environmentalists and MRC member countries on how to improve the dam design.

Deputy Minister of Energy and Mines, Viraphone Viravong said that once the government is convinced that it has addressed the concerns of the MRC member countries and environmentalists, it will make a decision on construction of the dam.

He could not confirm the extract time frame when the government will make a final decision on the dam, saying only that at present, the project developers are now building roads, labour camps and other facilities necessary to commence construction.

He confirmed that the government has not permitted dam construction on the Mekong mainstream to commence, and will wait until it is able to address the issues of those concerned.

 

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