Analysts say Chinese officials are diverting so much water from dams along the upper Mekong River system that Southeast Asian countries are going dry during prime agricultural seasons and turning to other powers for help.
Eleven southwest China dams have left much of the Lower Mekong region, with its population of 60 million, dry since 2019, according to data from the Stimson Center in Washington. The affected countries -- Cambodia, Laos, Thailand and Vietnam -- seldom complain because they are smaller than China and because of the relationships between some of their leaders and Beijing, analysts say.
Chinese dam authorities normally divert water but increase flows ahead of events with Southeast Asian officials to project a good image, Thitinan Pongsudhirak, a political science professor at Bangkok’s Chulalongkorn University, said. They divert it for domestic irrigation and power use.
“It’s very clear that the Chinese are using the dams for political leverage,” he said, meaning they increase the amount of water released when they want to improve relations with downstream countries.
“In the low season, the dry season, of course this is the most challenging for the lower, downstream countries,” he said.
Beijing began sharing upper Mekong River data in November through an online platform that it set up to provide “reliable forecasting and early warning services” on floods and droughts, Chinese state-controlled news website Global Times said in December. Laos, Myanmar, Thailand, Vietnam and Cambodia can obtain data from two Chinese hydrological stations in the upper Mekong basin, the report says.
Experts, though, believe that effort diverts attention from problems China has caused by what the Stimson Center calls “impounding” -- withholding -- water upstream before it can flow through Southeast Asia into the sea.
The lower river basin supports surrounding rice fields and the world’s largest freshwater fishery. Overall, the lower Mekong system supplies those living in the basin with about 80% of their animal protein needs, California-based advocacy group International Rivers says on its website.
“Chinese dam construction on the Upper Mekong is having devastating impacts on downstream communities, and dozens of dams are either planned, under construction or built within the Lower Mekong basin,” International Rivers says. “This rapid expansion of hydropower threatens all countries who share the Lower Mekong Basin, with downstream Cambodia and Vietnam at greatest risk.”
During a 2019 Mekong basin drought, the upper reaches in China received record rainfall but dams kept nearly all of it from flowing downstream, the Stimson Center website says. Without that diversion, it says, the Mekong along the Thai-Lao border would have seen above average flows from April 2019 onward.
“This is part of a long pattern that has driven numerous droughts,” the research organization says. “The increasing frequency of drought in the lower basin tracks closely to the way China restricts water upstream during the dry season.”
Since the completion of the Nuozhadu dam in 2012 on part of the Mekong in China’s Yunnan province, known there as the Lancang River, China’s dams overall have withheld more water than the previous 20 years, the Stimson Center says.
China's dams have also been suspected in causing floods, such as those 13 years ago along the Mekong in Laos. The Nuozhadu and another Chinese dam, the Dachaoshan dam, finished in 2003 and also on the Lancang, have generated “unexpected” releases that flooded places downstream and caused millions of dollars in damage, the research organization adds.
China’s Global Times attributes downstream floods and droughts of 2019 and 2020 to climate change.
'It's going to be huge'
In Cambodia, upstream diversions have weakened seasonal water flows that raise water levels in the Tonle Sap lake, said Phil Robertson, deputy Asia director of Human Rights Watch. Normally high waters flood surrounding land and create fish spawning grounds. The lake and adjacent floodplain yield up to 165 kilograms of fish per hectare.
The flooding once lasted three months but now stops after six weeks, he said. About 60% of Cambodians get protein from the lake’s fish, he added.
“There’s less flow coming down the river to push the water back up into the lake,” Robertson said. “It’s something that’s a core part of like Cambodian seasons, and if it stops happening, it’s going to be huge.”
Cambodia, like other lower Mekong countries, does not protest openly to China over river flows. These countries lack bargaining power with China, home of the region’s biggest economy and military. Poorer Cambodia and Laos depend heavily on China for aid and infrastructure investment. Laos benefits from its own dams, which Thailand finances and taps for electricity, Thitinan said.
Vietnam is considered the most affected downstream country as Mekong flows into the South China Sea near Ho Chi Minh City. Saltwater intrusion from the sea compounds the problem and exacerbated droughts of 2019 and 2020, according to United Nations data.
Officials in the country, which has a centuries-old rivalry with China, have no way to get more water released, said Alexander Vuving, professor at the Daniel K. Inouye Asia-Pacific Center for Security Studies in Hawaii.
“Vietnam of course has a lot of interest in opposing China in the subregion, but right now the tendency I see is that Vietnam is on the losing side,” Vuving said “It doesn’t have the wherewithal to cope with China.”
China continues to build dams along the upper Mekong and its tributaries. Laos is following suit, Thitinan said.
Although the four lower Mekong countries have an oversight organization, the Mekong River Commission, they are now turning to the United States and other countries for help in resisting China.
The Mekong-U.S. Partnership formed in September to offer anti-drought measures and earmark $6 million for work including access to water data for government planning purposes.
Remote monitoring and satellite data compiled by the United States this month tracked a 1-meter drop in river levels in the northern Thai district of Chiang Saen along the Mekong River due to a Chinese dam, media reports in Asia say. Japan is helping continental Southeast Asia accelerate industrial development and infrastructure to make these countries less dependent on farming.