Mekong Dam Monitor (Update for April 1 - 7)

 

Update for April 1-7

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 Even with Tuoba Dam Filling, Most Water in the Mekong Came from China in March Last month, China’s portion of the basin contributed the most Mekong flow (28%) compared to other sub-basin divisions (see map). Significant flows from China at this time of year are common as China’s large dams release water for hydropower and as the snow-covered portions of the Mekong Basin in China melt and send water into the river. China’s flow contribution would have been a few percentage points higher if the Tuoba Dam had not stored an estimated 163 million cubic meters of natural flow.

IMAGE OF THE WEEK Hydropower releases keep river levels near normal in March Over the last decade, dam releases for hydropower production have artificially lifted river volumes to 2-3 times the average March flow, creating severe environmental impacts along the river’s course. However, this was not the case in March 2024 as dam releases in China lifted the river to its long-term average (blue line), without which the river would have been much lower than normal. The cumulative effect of all 55 dams monitored throughout the Mekong Basin lifted flow at Stung Treng, Cambodia 46% higher than the long-term average. We estimate that if the Tuoba Dam in China were not filling, then March flow at Chiang Saen would have been about 8% higher and Stung Treng about 2% higher.

Where is the water? Dry season releases for hydropower production were moderate throughout the basin last week with a net release of just over 500 million cubic meters of water. The most significant releases came from Xiaowan (PRC, 164 million cubic meters), Jinghong (PRC, 144 million cubic meters), and Nam Ngum 1 (LAO, 132 million cubic meters).

Reservoir Series Over Time

River Levels River levels are very low from Chiang Saen to Nakhon Phanom. From Pakse downstream, river levels are normal and are lifted by releases from large dams in Laos, Thailand, and Vietnam. The Tonle Sap is slightly lower than normal for this time of year.

Chiang Saen Gauge Stung Treng Gauge

Weather & Wetness While much of the upper basin in China is wetter than normal, most of the lower Mekong Basin is hotter and drier than normal for this time of year with severe dryness observed around the Tonle Sap Lake. There is much evidence to suggest a dry season drought is forming. The Mekong Delta remains excessively wet due to irrigation from canals into agricultural fields as farmers prepare for the spring rice crop.