Mekong Dam Monitor (Update for December 4 - 10, 2023)

 

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Update for December 4 - 10 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 Dam Restrictions Exacerbated Already Low 2023 Wet Season Flow We estimate that total 2023 wet season flow (June to November) to Stung Treng, Cambodia would naturally have been about 315 billion cubic meters, about 14% lower than the long-term average. Yet dams restricted 23.46 billion cubic meters of water across the wet season, reducing the actual flow to 20% below normal at Stung Treng. China’s portion of the Mekong experienced drought during the wet season, and its wet season dam restrictions were about half of what all the downstream dams between Chiang Saen, Thailand and Stung Treng, Cambodia restricted. This is the second wet season in a row where China’s dams had lower restrictions than downstream dams across the six-month wet season. However, China’s dams are more impactful in parts of the river closer to China. At Chiang Saen, Thailand, China’s dam restrictions reduced natural flow by 20% across the wet season.

IMAGE OF THE WEEK Dam releases in November 2023 brought the Mekong River to normal levels Dam releases for hydropower production in the final month of the wet season are uncommon, but a cumulative release of 2.24 billion cubic meters of water in November 2023 brought flow to normal levels at Stung Treng, Cambodia. In recent years river flow in October and November have been close to normal, while river flow from June through August has been much lower than normal due to a lack of rainfall and upstream dam restrictions. This image shows that half of November river flow entered the Mekong between Nakhon Phanom, Thailand and Stung Treng, Cambodia.

Where is the water? We tracked a net release of 633 million cubic meters last week. 12 dams released water for hydropower production with the largest releases coming from Nam Ngum 1 (202 million cubic meters, LAO) and Nam Theun 2 (349 million cubic meters, LAO).

Reservoir Series Over Time

River Levels Eyes on Earth estimates there is 11% extra water from upstream dam releases at Chiang Saen, Thailand. As dam releases continue into the dry season, the percentage of extra water will increase and artificially raise the level of the river. Higher than normal river levels negatively impact fishers and community livelihoods, particularly in areas closest to dams which release water. River levels along the Thai-Lao border are slightly lower than normal for this time of year, while levels from Stung Treng downstream are normal.

Chiang Saen Gauge Stung Treng Gauge

Weather & Wetness The Mekong is experiencing normal to high levels of wetness in the most upstream and most downstream portions of the basin. Extreme dryness is observed in northern Laos and parts of Thailand. Much of the extreme dryness is due to much higher-than-normal temperatures in the central part of the basin.