ศาสตร์เกษตรดินปุ๋ย : ขอบคุณแหล่งข้อมูล : หนังสือพิมพ์ The Nation
http://www.nationmultimedia.com/news/aec/aec/30291229
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July 23, 2016 01:00
By News Desk
Viet Nam News
By News Desk
Viet Nam News
HANOI – Southern Vietnam is highly vulnerable to more drought and salinisation in the future when its fellow countries in the lower Mekong river basin irrigate the river water to serve their expanding farm land, experts warn.
The lower basin of the trans-boundary Mekong River starts from Laos and runs through Thailand, Cambodia and Vietnam before emptying into the East Sea (South China Sea). Any attempts to interrupt the natural status of the river would pose risks to Vietnam’s Cuu Long (Mekong) delta where more than 17 million people rely on the river for a living.
Apart from the biggest threat coming from a string of major hydroelectric projects and dams along the Mekong river, such interruptions now even include new irrigation systems in the other three lower Mekong nations. They would drain more water from the river to support their growing agricultural sector and leave less water for Vietnam, said Nguyen Nhan Quang, an independent researcher on river basin management at a workshop held by local non-profit organisation PanNature on Tuesday.
In its economic development master plans with vision to 2027, Thailand – one of the four lower Mekong nations – was aiming to transform its northeast region where the Mekong river runs to a food growing and bio-fuel producing centre of the nation, Quang said.
“Therefore, new constructions and renovations to the irrigation system draining water from the Mekong River (in Thailand) are just a matter of time,” he said.
“Thailand is planning some 990 irrigation projects most of which are to pump water out of the Mekong”.
Cambodia and Laos are also on their way to expand their farming land to grow rice and industrial crops. Quang said that Cambodia would add some 6,000 ha to the current 504,245 ha while Laos is planning a massive 238,617 ha of new agricultural land plus the existing 166,476 ha.
“Cuu Long delta is under tremendous strain when the water level will go down and down gradually,” Quang said.
‘Very dangerous’
Nguyen Hong Toan, a member of the Vietnam’s Mekong River Commission, said at the workshop that Mekong water redirection was not new but had been initiated since 1960.
“Yet it was not until 2014 that Thailand and Cambodia redirected the river water on a larger scale,” he said.
Thailand by now is working on a project to irrigate Mekong river water through Nong Han district in Udon Thani province to Lam Pao dam. The dam reservoir would be expanded to about 45 sq kilometres to hold water in addition to another new 30 reservoirs to be built. The water volume in and out annually would reach about 2.8 billion cubic metres, according to Quang.
Cambodia, meanwhile, is building the US$200 million Vaico irrigation channels that link the Mekong River to the Krapik lake whose water volume is about 100 cubic metres.
“The construction of hydroelectric dams has caused so many difficulties for the Cuu Long delta already. But now, hydroelectric combining with water redirection is very dangerous for our country, especially when we are at a disadvantaged geographical location like this,” Toan said.
“About 95 per cent of the water flow into the Cuu Long delta comes from outside the country. If the water level is down, the delta will have to face even more serious drought and salinisation than ever before.”
The Cuu Long delta this year was hit the worst drought in the last nine decades along with saltwater intrusion on a mass-scale. Vietnam’s biggest rice basket suffered losses worth more than 4.7 trillion dong (US$215 million) due to the disasters, with some 225,000 households short of fresh water.
Hydroelectric dams and irrigation systems would further cost 60 per cent of the silt essential for agriculture in the Cuu Long delta where more than half of the country’s staple food crops is grown, said Tran Xuan Thai from the Vietnam Academy for Water Resources.
An expert of the Institute for Water and Environment Dang Thi Ha Giang believed that interest conflicts between countries to use the water resources in the Mekong river basin were “unavoidable”, yet they should all calculate carefully to avoid “immeasurable consequences”.
“Experiences learnt from other rivers… show that with benefits gained in the upper, the costs are paid by the lower,” she said.
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