Dam it! Man-made changes to Mekong River threatens delta dwellers

Ailing river: A Cambodian woman washes fish in the Mekong River in Phnom Penh, Cambodia. Mekong Delta dwellers are suffering from the effects of climate change and upstream hydropower projects. - EPA

Dams, climate change and development – all are causing problems for Mekong delta dwellers.

Vo Van Co, a 49-year-old farmer at Vuon Man Ba Ho orchard in the Mekong Delta province of Can Tho in southern Vietnam, feels the environment has changed, as rain and water levels have fluctuated in recent years and affected his work – but he doesn’t know why. “Too much rain and water is not good for fruit gardens, but flood and erosion are worse for us as we plant on the bank of the river,” he says.

Co doesn't own the 1.7ha orchard but is an employee who earns his living from the garden. The yield from the fruit affects his life and family, he says. Changes in the Mekong River and the delta over recent years are not illusions – concerns have been raised by local people and officials in Vietnam.

Ecologist Nguyen Huu Thien says the delta now faces three major threats: climate change, errors in domestic development, and projects upstream on the Mekong River. The impacts of climate change were real and people had felt them, he says, noting that rising temperatures and an increase in the sea level had happened, along with less predictable rainfall and stronger storms.

Mistakes from development have occurred in all countries around the world, including the Mekong Delta in the far south of Vietnam. Development activity aimed at boosting economic growth has polluted the environment and damaged the ecological system. The impact from climate change had been gradual and people have adapted.

The government could also correct mistaken development by changing its policies, Thien says. But the sudden impact from projects upstream, notably hydropower dams, was the biggest concern for people downstream of the river. “Our concern is that once dams are built, the impact will be permanent and irreparable,” he says.

Countries upstream on the Mekong are building and planning to build a number of hydropower projects that will block the river. China has built five dams in the northern-most section and plans to build three more on the river’s mainstream. Laos is building one in Xayaburi, south of Luang Prabang, and plans another at Don Sahong in Siphandon, near Cambodia. 

Huge structures blocking the flow of a river like the Mekong is a real problem for many downstream whose livelihood depends on the river. Thien says dams alter the flow of sediment and fish migration. Sediment is important for the formation process. The Mekong Delta would never have formed without sediment deposits from upstream tens of thousands of years ago, he says. 

Sediment also brings nutrients to feed animals and fertilise plants in the delta. It's important for agriculture, aquaculture, the ecosystem and marine life, Thien says. Less sediment would cause a “hungry water” phenomenon, eroding banks and the river base. Building more dams upstream would also affect the delta’s hydrology – and water means everything for people in the area.

“We are near the sea, so businesses depend on freshwater and sea water, and at the boundary of salinity coming into the delta is a battle between freshwater and the sea,” Thien says.

If the freshwater current is weakened, seawater would intrude further. Operating dams upstream affects the flow of freshwater into the delta. “That means it will be very difficult to predict where the boundary of salinity will be,” Thien says. This was making things very difficult for people in the delta, who have to adjust their livelihoods to adapt to rapid changes, he says.

Another problem, which has been widely noted, is fish migration, as the dams create barriers that prevent them going up and down the river. There are two major kinds of fish in the delta: black and white. The white fish needs to migrate annually to breed. “Fish is an important source of protein for us, such that it is not replaceable,” Thien says.

Some people say aquaculture could replace this natural source of protein for people, but Thien disagrees, saying that aquaculture fish depend on wild captured fish for feed, and aquaculture fish also depend on “trash” fish from marine catches, “and thus goes back to the problem of nutrient supply”.

The Vietnamese government is preparing a Mekong Delta Plan with a vision for the year 2100, with help from officials from the Netherlands. But with potential impacts from upstream development still not clear, no immediate measures have been proposed yet on how people in the delta should adapt, Thien says.

Le Duc Trung, director-general of Vietnam’s National Mekong Committee, says the impact from upstream dams had already been felt in the delta after five dams in China – on water levels, sediment loss and erosion now occurring. Trung says Vietnam may have some plans to handle the situation, but as 90% of water flow to the delta comes from upstream countries, a more effective way to manage the problem is to get co-operation from them. — The Nation/ANN

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Environment , Environment , Mekong , dams , river


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