At a conference discussing the development of hydroelectric dam Donsahong, set to be built on the mainstream Mekong River in Laos, held in Can Tho City last week, a farmer named Nguyen Van Hiep in Dong Thap Province cited emerging upheavals. He said that before hydroelectric plants were built on the river, farmers in the delta could deal with annual flooding in an easy way because natural floodwater flow is predictable.
Now with those plants, they find themselves helpless in dealing with flooding as its flow has changed and gets stronger, he said, adding that with many dams being developed on the river, people in the downstream areas will suffer.
During the rainy season, a huge amount of water will likely be released from those dams, aggravating flooding, while in the dry season, the river water flow in the area will dwindle as dam operators store water for power generation, causing more severse saltwater intrusion in the delta, Hiep said.
According to researchers, Donsahong dam will cause downstream areas to lose half of the water amount in the dry season because water from 17 tributaries of the Mekong River at those areas will flow into the Housahong branch, which is blocked by the dam.
Studies also revealed that 75% of fish resources in the river will move to Housahong branch, and therefore, aquatic resource depletion will occur.
Le Anh Tuan, head of the Research Institute for Climate Change of Can Tho University, said Donsahong is the second hydroelectric project on the mainstream of the Mekong River to be constructed in Laos.
The 32-meter-high dam has no water reservoir and has a designed output of 260 MW.
He said 19 hydroelectric projects have either been operational or are planned to be constructed on the river mainstream, including eight projects in China, nine projects in Laos and two others in Cambodia.
Hydropower plants on the Mekong River have potential to generate 54,000 MW but the development of those plants on the river mainstream has been warned to put many species of fish at high risk of extinction.
Tuan said hydroelectric plants will cause an imbalance in the supply of water, fish reproduction and alluvium, and degrade the ecosystem in the Mekong Delta.
Duong Van Ni from the university said under the effect of climate change, hydroelectric projects will open the way for saltwater to intrude deeper into the delta.
Source: Viet Nam Net | 27 August 2014