Chinese dams along the Mekong River hold a massive amount of water in their reservoirs, but the government in Beijing might need to be paid to release water for downstream communities afflicted by droughts, a panel of experts said Tuesday.
More than 70 million people from five Southeast Asian countries depend on the mighty Mekong for their livelihoods, primarily through fishing and agriculture. But China operates 129 dams upstream, including 11 mega-dams and has at least seven more in the pipeline.
Such projects siphon off a significant amount of water before it reaches countries downstream, including Cambodia’s Tonlé Sap Lake where 2 million people depend on its fisheries, according to experts.
“Those fishers are at risk [due to the] upstream dam restrictions during these times of low flow,” Brian Eyler, co-leader of the Mekong Dam Monitor, a project by the Stimson Center, a Washington think-tank, said during an online panel discussion. “I think there’s one thing that has to be addressed is how you compensate China for releasing water during the wet season.
“For better or worse, these large dams were built in China. They’re there for a reason. There’s a profit motive behind them … and when you ask somebody to stop doing that, you’ve got to give something in return,” Eyler said during an online panel discussion on Tuesday.
Only two Chinese dams on the Mekong hold about 10 billion cubic km of water during the wet season to produce hydroelectricity during the dry season: the Xiaowan, the second largest dam in the Mekong River system, and the Nuozhadu, one of the world’s largest dams.
Together, they hold about 20 percent of the water held back during the wet season, according to Eyler.
The easiest solution, he said, would be to engage China since both dams belong to “one owner,” and “one government that oversees the operations.”
Insurance industry role
Offering a potential solution, Alan Basist, a climatologist and co-leader of the Mekong Dam Monitor, said the insurance industry could collect money from lower basin countries and use those funds to offset China’s financial loss.
“For example, the insurance industry goes to China and says we will pay you to release the water. We know that you will lose money because you cannot sell the energy during the dry season,” Basist said during Tuesday’s panel discussion.
“Those types of arrangements have been done in different parts of the world, very successfully,” he said. “One of the advantages is that they can do an assessment of the economic and the environmental cost, and then adjust the payments so that it’s in line with the impacts that would happen.”
Eyler agreed, saying “The insurance option … is actually one of the cheapest and the most equitable options because it’s not necessarily the fishers of the Mekong who are paying, putting up the cash for that.”
A prolonged drought
Experts have said that the Mekong is experiencing record low flows with longer dry and shorter wet seasons. The system is entering the fourth year of a prolonged drought caused by a lack of rainfall during the wet season, as well as a significant reduction of flow as dams upstream hold back a substantial amount of water.
“We’ve been using satellite observations to identify how the water is flowing or not flowing through the Upper Mekong and we’ve learned very clearly that the dams have the ability to hold back a tremendous amount of water,” Basist said.
“So, we’re seeing a significant reduction of flow,” he said.
Meanwhile, Eyler said sudden releases of water by upstream dams could shock the river.
In 2021, upstream dam releases on 22 occasions caused the river to rise by more than half a meter and then decrease by an equal amount when the releases stopped, he said.
The water level increased or decreased by more than one meter on several occasions, Eyler said, adding “This is really concerning.”
Fish will get confused
The Mekong is also one of the world’s largest and most biodiversity-rich river basins, but the fluctuating water levels can harm species of birds and plants, experts say.
Birds nest and lay eggs along the sandy river banks during the dry season, but the rising water levels can destroy the habitat and threaten critically endangered species, he said. Similarly, some trees along the Ramsar wetland protected sites in Cambodia are dying because of river changes.
The river basin has more than 1,100 species of fish, which also are affected by the river’s changes. The dams worsen the impact of periodic droughts in the Mekong basin and rob the river of the “pulse effect” that spreads nutrients that support fisheries and farming, experts said.
Nguyen Huu Thien, an independent climate and environmental consultant based in Vietnam, said those changing river signals are having a negative effect.
“The entire ecosystem of the Mekong, especially migratory fish, depends on the fluctuation, the pulse of the floods, for starting the lifecycle activities, such as migration, and the seasonality of the flows,” he said.
“The fish will be confused. They don’t know when to start migrating upstream to breed and I think we can expect that the fishery of the Mekong … is going to be wiped out.”
“If the fish are confused, if the natural rhythm … is not happening, and the flows are not occurring as would naturally happen with all these dams altering the natural rhythm of the river, then the Tonlé Sap Lake is no longer getting the pulse of the larvae, and that severely impacts the fishing industry,” he said.
The Tonlé Sap Lake fishing industry has fallen about 40 percent compared to its long-term historical record, Basist said.
Eyler said all blame should not be aimed at China.
While the 11 largest dams are in China, Thailand has 152 completed dams, Eyler said, adding most are small and used for agricultural purposes. Laos has 68 dams and 37 more are under construction, Vietnam has 78 dams and Cambodia has nine.
“So, it’s not just a China issue and how China is operating its dams that’s changing the nature of the river,” Eyler said.
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