Mekong Dam Monitor (Update for Nov. 20-26, 2023)

 

Mekong Dam Monitor Sharing Data. Empowering People

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Update for November 20-26 Notable changes on the Mekong in the last week. Visit the Monitor home for more, including Burmese, 中文, Khmer, ພາສາລາວ, ไทย, and Tiếng Việt translation.

SPOTLIGHT China’s Nuozhadu Dam reservoir fills to only 50% in 2023 Analysis of satellite imagery suggests 2023 reservoir levels peaked at the Nuozhadu Dam around October 25 at just under 50% of the reservoir’s storage capacity. Below average wet season rainfall is likely the cause of the low reservoir level. Since Nuozhadu is China’s largest dam, this equates to less water availability across all of China’s 11 dams. Because of this, the Mekong River will flow much closer to natural flow levels over the course of the 2024 dry season and endure fewer ecological and socio-economic impacts than previous dry seasons. 2022 also had a similar pattern of lower-than-normal reservoir levels, which led to lower-than-normal levels of hydropower production from China. While the reduced negative impacts will be welcomed, the poor performance at Nuozhadu shows hydropower generation can be unreliable in areas of persistent wet season droughts. The Nuozhadu reservoir has not reached full reservoir capacity since 2020.

Where is the water? We tracked a small net release of 227 million cubic meters last week. 11 dams released water for hydropower production with the largest release coming from the Nam Ngum 1 dam (169 million cubic meters, LAO). The Nuozhadu Dam (PRC) had a slight restriction of flow which resulted in an 0.80 meter drop in river level along the Thai/Lao border on November 27-28.

Reservoir Series Over Time

River Levels Eyes on Earth estimates that about 34% of flow at Chiang Saen is currently restricted by China’s dams. River levels along the course of the Mekong mainstream are below normal for this time of year.

Chiang Saen Gauge Stung Treng Gauge

Weather & Wetness Extreme wetness in the upper basin is providing excess water in the last weeks of the wet season. Temperatures there are above normal, keeping the surface of the upper basin above freezing and allowing more water to flow into the Mekong. Northern Laos is drier than normal, while most of the rest of the lower basin in Laos, Thailand, Cambodia, and Vietnam is wetter than normal for this time of year.