>> Experts warn of risks from Lao dam project
>> Lao plan to build dam harms Vietnam: expert
The Mekong region could create equivalent power while causing dramatically less damage to river flows by opting for tributary rather than main channel dams.
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| Insufficient environmental evaluation and uncontrolled dam development could damage fish migration on the Mekong. |
The Worldwide Fund for Nature (WWF) recently announced a new study on aquatic ecosystem connectivity on the Mekong River.
The findings suggest that insufficient environmental evaluation and uncontrolled dam development could push the Mekong past a tipping point, where the vital natural processes that support this unique ecosystem, such as sediment and nutrient transport and fish migration, would be irreparably damaged.
“No part of the Mekong River still provides connectivity to all the 13 ecosystem types classified by a recent WWF study,” said Nikolai Sindorf from WWF Conservation Science Programme, adding that “The impact of continuing incremental dam development will increasingly disconnect these river systems.”
Xayaburi, the first of 12 dams proposed for the Mekong stream, is projected to produce 1,260 MW of power while reducing the basin’s total connectivity by 5%. In contrast, the 1,070-MW Nam Theun 2 dam on the Nam Theun River in Laos took only 0.8% out of the Mekong’s connectivity. The 1,540-MW Se San cascade of 6 dams also decreased connectivity, but only by 1.2%.
The proposed Xayaburi dam would cut off 9 aquatic ecosystems upstream; out of a total of 13, using WWF’s classification. In the meantime, both Nam Theun 2 and the Se San cascade only block a single ecosystem in relatively small areas of the river basin.
Ecosystem connectivity is critical to maintain the river and its ecological processes.
“The impact of basin-wide dam planning on ecosystem connectivity needs to become one of the measures against which projects are assessed,” said Dang Thuy Trang, Manager, Sustainable Hydropower and River Basin Programme, WWF Greater Mekong Programme.
“This will make it easier to develop the Mekong basin with a much smaller environmental footprint. Ultimately, this would lead us to a situation where local energy demands are met, and relevant ecosystem processes are conserved basin-wide,” he said.
WWF is calling for a 10-year delay in the approval of the mainstream dams to fully consider the costs and benefits of their construction and operation. Immediate energy needs can be met from multiple hydroelectric projects on some selected Mekong tributaries where connectivity impacts are much lower.
