Friday, June 12, 2009

Saltwater intrusion adds to Vietnam's water woes

Tran Dinh Thanh Lam in IPS: When they got out of bed one morning in April this year, the residents of Vi Thanh City here in southern Vietnam’s Mekong Delta were surprised to find that their water had become salty. During the night, seawater had intruded into the Xa No canal, the main source of water for the city of 200,000 people.

…For daily use, inhabitants now have to buy fresh water supplied from the nearby regional centre of Can Tho at high prices. A dam is being built to prevent the penetration of saltwater, but it will not be finished until 2011. The area’s farmers also worry that their 37,000 hectares of paddies and aquaculture could be totally destroyed by the seawater intrusion.

Many factors are being blamed for the change in water quality - hydropower construction upstream on the Mekong River, global warming, and, ironically, the network of small dams build by local farmers themselves to protect their crops and aquaculture products….

There are two seasons in the Mekong Delta, the dry season, usually taking place from May to November; and the rainy season, from December to April. During the dry season, the water level of the Mekong is very low, enabling the intrusion of saltwater. During the rainy season, the Mekong overflows, flooding the delta but also washing out the areas recently invaded by seawater.

To fight these floods, local farmers have built a network of dams to protect their crops and aquaculture products - a method that in previous years was acclaimed as an innovation because it helped farmers continue producing even in the rainy season. Now, however, these dams have turned out to be one of the causes of saline intrusion….

Narrow bridge over canals at An Binh Island near Vinh Long in the Mekong Delta. Photo taken 28 Feb 2007, on Canon handheld camera. Released to public domain Mar 8 2007, by Deadstar

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