The Mekong Dam Monitoring Project (MDM) said that 19 dams across the Mekong River basin released more than 3.3 billion cubic meters of water during the week (from May 15 to 21). The largest amount of water released came from China's dam, such as: Nuozhadu, which released more than one billion cubic meters; Xiaowan and Huangdeng dams each released more than 500 million cubic meters. Some other dams in Laos released 100 - 200 cubic meters of water.
China's hydropower plants release billions of cubic meters of water to prepare for the rainy season
According to observers, in 2022, the La Nina phenomenon caused heavy rain and Chinese hydroelectric dams were always in a state of releasing a lot of water into the Mekong River. This caused the water level of this river to always be higher than the average of many years. On the contrary, in 2023, La Nina gradually ended and was transitioning to El - Nino (drought), so Chinese hydroelectric dams released very little water during the dry season. This caused the water level at many measuring stations on the Mekong River in the entire month of April and the first 2 weeks of May 2023 to be lower than the average of many years. However, when the rainy season began in the downstream area, these dams increased their water discharge. This will cause the water level of the river in downstream Thailand to increase significantly due to these dam releases.
MSc. Nguyen Huu Thien, an expert on biodiversity in the Mekong Delta, analyzed: The rainy season has now begun and recently, there was a snow melt that added water, so dams in China released water to welcome the rainy season. As of the end of May 2023, dams in Laos and the basin had very little water left. Specifically, 25 dams in Laos had only 4 billion cubic meters left, 7 dams in Thailand had only 0.6 billion cubic meters left, but large dams in China, the Mekong, Xiaowan and other mainstream dams still had more than 9 billion cubic meters.
However, if El Nino is extreme in the near future, with low rainfall this rainy season, the dams will continue to store water, preventing the flood season from reaching the Mekong Delta. In the dry season next year, if El Nino is strong, when the Mekong Delta is severely affected by drought and salinity, the dams will store more water, slowing down the flow of water, making the drought and salinity situation in the Mekong Delta even more severe.
"The operation of the Mekong hydropower plants disrupts the hydrology of the Mekong River, making it no longer natural. In extreme drought or flood situations, the dams will make the situation even more extreme," Mr. Thien commented.
According to the forecast of the National Center for Hydro-Meteorological Forecasting on the Mekong River water level, from now until August 2023, the total flow from the upper Mekong to the Mekong Delta tends to increase gradually but is still lower than the average of many years by 10 - 15%. The flood level in the upper Mekong River fluctuates with the tide with a gradual upward trend and is likely to peak in late September and early October 2023, at levels below alert level 1 to alert level 1. However, at downstream stations, the flood peak is likely to appear in late October and early November 2023 at alert level 3 and above alert level 3.
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