Mekong Dam Monitor (Update for September 23 - 29, 2024)

 

Update for September 23-29

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 Mekong Floodpulse ignites in late September. Over the most recent two weeks, the Mekong Floodpulse has significantly expanded as Typhoon Yagi’s floodwaters combined with precipitation over Cambodia and Vietnam’s Mekong Delta. The Tonle Sap is now on track for a normal expansion in October assuming normal weather patterns. Typically the expansion peaks in September and stays at peak for one month or more. A robust floodpulse drives the productivity of fisheries throughout the Mekong Basin (especially in Cambodia) and provides freshwater for agricultural production in Vietnam long into the dry season.

IMAGE OF THE WEEK Theun Hinboun Expansion Reservoir Fills Significantly in September The Theun Hinboun Expansion reservoir rose by over 10 meters in September, increasing its volume by 1 billion cubic meters. Dams throughout Laos are now estimated to be at 85% reservoir volume capacity, restoring their reservoirs with runoff from major precipitation events like Typhoon Yagi.

Where is the water? A huge net restriction of 3.2 billion cubic meters was observed last week across 18 dams we monitor. The largest restrictions came from Xiaowan (CHN, 529 million cubic meters and now 100% full), Nuozhadu (CHN, 154 million cubic meters), Nam Ngum 2 (LAO, 501 million cubic meters), Nam Ngum 1 (LAO, 117 million cubic meters), Nam Theun 2 (LAO, 462 million cubic meters), Theun Hinboun Expansion (LAO, 524 million cubic meters), Ubol Ratana (THA, 501 million cubic meters), Nam Kong 1 (LAO, 117 million cubic meters), Plei Krong (VNM, 134 million cubic meters), Lower Sesan 2 (CAM), 136 million cubic meters). Currently reservoir levels throughout the Mekong are the highest in three years.

Most Impactful Dams

River Levels River levels throughout the basin are trending downward. From Chiang Saen to Vientiane, river levels are now below normal while from Nakhon Phanom to Stung Treng river levels are still significantly above normal. The Tonle Sap River level remains about one meter below normal and is starting to trend downward.

Chiang Saen Gauge Stung Treng Gauge

Weather & Wetness Most of the upper basin was drier and warmer than normal, and these warm temperatures are reducing the snowpack which typically feeds the river in the dry season. The warm dry weather extended into northern Laos and northeast Thailand, as well as northern Cambodia. Southern Cambodia and Vietnam’s Mekong Delta were wetter than normal for this time of year.

Mekong Dam Monitor in the News The Mekong Dam Monitor team hosted a capacity building workshop at Chiang Mai University to build remote sensing skills and address calls for more data driven approaches to transboundary issues. Learn more here.