VietNamNet Bridge - Scientists have once again raised their concerns about water security in the Mekong Delta, saying that hydropower dams on the Mekong River's upper course as well as Thailand, Laos and Cambodia’s plans to divert the river are the biggest threats.

Le Anh Tuan, deputy head of the Can Tho University’s Research Institute for Climate Change, said the Mekong Delta is facing six challenges: climate change; population increase and migration; natural resources overexploitation; environmental degradation; hydropower dams; and Mekong diversion plans implemented by Thailand, Laos and Cambodia.

Of the challenges, Vietnam can adapt to climate change, prevent population increase and migration, stop natural resource overexploitation and use the land in a more effective way. But it cannot adapt to or control hydropower dams and diversion projects.

The building of hydropower dams on the Mekong River from China to Laos not only forces thousands of people to relocate their houses, it changes the current in the lower course and causes loss of millions of tons of alluvium in the Delta.

With six hydropower dams in Yunnan province in China, the volume of alluvium reaching the Mekong Delta has decreased from 160 million tons per annum to 85 million, which means that nearly 50 percent of alluvium volume is retained at hydropower dams. 

“This will lead to a ‘thirst’ for alluvium, which will lead to more serious landslides in the Mekong Delta,” Tuan said.

In the dry season, the Mekong River’s flow to the lower course is 2,500 cubic meters per second and is lower in dry years (the lowest reported level was 1,200 cubic meters per second).

Thailand is considering a current diversion plan under which it would take away the Mekong’s water in the dry season (1,200 cubic meters per second), while Laos is considering a diversion project to get water for 20,000 hectares of cultivated land (240 cubic meters per second), and Cambodia is considering Vaico project to have water for 100,000 hectares of land (500 cubic meters per second).

The total volume of water to be taken by the projects would be large, leaving little for the Delta in Vietnam.

Nguyen Nhan Quang, former deputy secretary general of the Vietnam National Mekong Committee (VNMC), warned that water would not reach Vietnam because of the the Mekong water diversion projects, even if hydropower reservoirs discharge water.

The Mekong Delta receives 85 percent of total water volume from the Mekong mainstream every year. All daily activities and agriculture and fishery production in the delta rely on the water source.

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