Dams will kill Mekong River downstream, say experts

A portion of a dike seriously eroded in the Mekong Delta’s Bac Lieu Province in February. Dams built upstream on the Mekong River will kill the fish, limit silt and cut off a major water source for agriculture in Vietnam and other downstream nations, experts warn.

As part of a series of eight dams on the upper half of the river, China recently completed the Xiaowan Dam, which is the world’s tallest at 292 meters and whose storage capacity is equal to all Southeast Asian reservoirs combined. “China’s extremely ambitious plan to build a massive cascade of eight dams on the upper half of the Mekong River, as it tumbles through the high gorges of Yunnan Province, may pose the single greatest threat to the river,” AP cited a United Nations report released last Thursday. Ky Quang Vinh, head of the Center for Natural Resources and Environment in the southern city of Can Tho, told Tuoi Tre newspaper that dams are already big at heights of 15 meters. “And 292 meters is unbelievable,” he said. The Mekong River runs through six countries: China, Myanmar, Thailand, Laos, Cambodia and Vietnam. The last four nations are also planning to build damns on the river’s main flow through their countries. “The Mekong is being cut into pieces,” Vinh said, adding that the dams will disturb the life of fish in the river, partly by blocking their movement. They also pose the threat of extinction to rare fish species such as fresh water Irrawady dolphin, the Mekong giant catfish, and numerous other kinds of migrant fish. The river, which is one of the highest fresh-water fish suppliers in the world, is providing fish to more than 60 million people. In Vietnam, the river is known as the Cuu Long River as it flows through the southwestern region. As the Cuu Long is the final part of the Mekong, Vinh said it will be “severely disturbed” by the dams along the river, which are expected to go beyond 20 in number. Construction of the dams means no more profit from fish in the river and a big drop in ecosystem-balancing creatures such as seaweed and microorganisms, he added. Recent statistics have shown a dramatic drop of fish in the river. The UN report found increasing shortage of water at several river basins such as Tonle Sap in Cambodia, Nam Khan in Laos and Sekong-Sesan Srepok in Cambodia and Vietnam. Ngo Dinh Tuan, scientific council chairman of the Southeast Asia Institute of Water Resource and Environment (SAIWRE), said people should have built the way for fish to swim through the dams. He said the dams will retain the silt and thus, land in the downstream area will become susceptible to land erosion and landslides. China had started building dams on the Mekong from 1950 onwards to bring water northward for hydropower production, Tuan said. But according to many experts, the move aims to switch water from the Mekong to the Yangtze River to supply water to dry areas in northern China. Tuan said this would mean that the Cuu Long River dries up. “That will be extremely dangerous.” Vinh also said “the most visible impact of the dam construction is severe shortage of fresh water.” Mekong Delta residents have suffered severe water shortages in the dry season last month and will suffer more in the coming years, he said. The water flow during the annual flooding of the river has also reduced from 40,000 cubic meters a second in the past to 28,000 cubic meters last October. Farmers in the river delta had to struggle to find water for the winter-spring crop earlier this year, Vinh said. Coastal provinces of the delta such as Tien Giang, Ben Tre, Tra Vinh, Soc Trang, Bac Lieu and Ca Mau have experienced saline intrusion of up to 70 kilometers into the mainland during the dry season. Vinh said the Chinese 292-meterhigh dam can in the long-term direct water to dry areas in China, and be used for irrigation or hydropower plants. But for now, it is going to cause flooding in a large area on the dam, which will change the local ecosystem and probably kill several rare species in the river, he said. According to the UN, the dam development will lead to “changes in river flow volume and timing, water quality deterioration and loss of biodiversity.” Less fish and unpredictably changing water flows in the river will jeopardize already difficult livelihoods for locals, Vinh said. Vinh cites official figures saying the river generates incomes exceeding US$3 billion a year, but adds its true value is much more as its aquatic creatures are diverse, second only to the Amazon, and ensures food security for dozens of millions of people. Almost 800,000 square kilometers of the river network is home to dozens of rare bird and marine species, including the Mekong giant catfish, and provides food and jobs for 65 million residents in the river basin. The Mekong River Commission, a riparian organization on issues of common concern, will have very little influence on this issue as long as China and Myanmar do not join it, Tuan said. China even argues that the river is national, not international, the council chairman added. The two countries also conceal their hydropower operations and such noncooperation is “dangerous,” Saigon Tiep Thi newspaper on Monday cited Dr. Le Anh Tuan from the Research Institute for Climate Change of Can Tho University as saying. The dam construction now joins hands with climate change to worsen droughts, salinity intrusion, landslides and land erosion, he said. China has built big dams on the river’s main flow while other countries have only built them on tributaries so far, he added. Tuan of SAIWRE said Vietnam should cooperate with international organizations to stop upstream overexploitation of water. “We have to accept if a country builds dams for hydropower production but have to strongly protest when the water flow is turned away.” The Vietnamese government must create a national strategy for protecting the river downstream, not only for the Cuu Long River but the Red River as well, Tuan said, since China has started to build dams on it. Source: Agencies