A cascade of six dams being built in southern China has caused significant changes to water levels in the Mekong River as far downstream as Cambodia, according to a study released by researchers from Finland and Laos.
The study—by Timo Ras- anen of Finland’s Aalto University and Paradis Someth, a water researcher affiliated with the Mekong River Commission (MRC)—comes as the commission is beginning consultations on the construction of a third mainstream dam on the lower Mekong in Laos.
Mekong water levels have increased during the dry season and decreased during the wet season at several sites on the river as a result of China’s dams, according to the study, which was released earlier this month.
Water levels in Kratie province, for example, have been 74 percent higher in the dry season over the past five years compared to the long-term average, the study says.
While there are some potential positive impacts—more water available during the dry season makes the river easier to navigate—the study says that overall the deviations threaten the livelihoods of those living on the river, destroy fish habitats and unpredictably flood houses and fields.
Maureen Harris, the Southeast Asia program director for the NGO International Rivers, agreed that the dams in China were causing irregular spikes in water levels as they discharged water from their reservoirs.
“Some people have had property destroyed from these fluctuations. Some have lost shopfronts, lost farms,” Ms. Harris said.
Ms. Harris, whose NGO has worked extensively with communities affected by hydropower projects on the Mekong, said the Chinese dams often released water without warning, with no information reaching those whose rice fields, fish traps and water buffaloes might be affected.
“China’s been quite resistant to engaging in multilateral platforms. There’s been some recent data-sharing…but the information is inadequate,” Ms. Harris said.
Current dam developments on the Mekong stand to make the situation worse, she said, citing plans “for another cascade in China, upstream of the current cascade.”
As for Pak Beng, the planned third dam in Laos, she noted that all of the dams under construction on the lower Mekong were being operated by different developers, and there was no system to coordinate them effectively.
Mao Hak, a spokesman for the Ministry of Water Resources and Meteorology, said he found the reports’ conclusions difficult to believe because the MRC had never alerted the ministry of any such fluctuations.
Reached on Monday, MRC CEO Pham Tuan Phan said the intergovernmental commission “is constantly trying to improve its relationship with China both in sharing information and water flow.”
Cambodia’s Environment Ministry was unable to provide immediate comment.