Mekong Dam Monitor (Update for August 26-September 1, 2024)

 

Update for August 26-September 1

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 Lower Mekong Floodpulse Remains Extremely Weak and Far Behind Schedule The Lower Mekong Floodpulse only expanded by 600 square kilometers when it typically expands by several thousand kilometers between early and late August. Much of the poor performance is a result of upstream damming. A normal floodpulse expansion drives robust fisheries and agricultural production in Cambodia and Vietnam. Despite the floodpulse’s poor performance so far, it is still possible to reach a normal expansion of nearly 20,000 square kilometers. A huge pulse of water which originated from flash floods in the upper Mekong is working its way into Cambodia and will cause more expansion over the coming weeks. For the past three years, the floodpulse has peaked in October.

IMAGE OF THE WEEK Watch the Songkhram River’s floodpulse During the wet season, many parts of the Mekong Basin experience seasonal inundation similar to the Tonle Sap Lake. The annual floodpulse in Songkhram River, an undammed Mekong tributary in northeast Thailand, drives local fisheries and provides food and livelihoods for the people living along its 420-kilometer course. Like the Tonle Sap Lake, the Songkhram’s floodpulse has suffered. Recent flooding drove what appears to be a robust floodpulse process during the month of August, although further study is required to confirm this conclusion. This image shows a small portion of the Songkhram River near its mouth. For reference, the image is 50 kilometers wide.

Where is the water? Last week we tracked a large net cumulative restriction of flow of over 1.3 billion cubic meters of water across 21 dams throughout the basin. Major restrictions came from Nuozhadu (CHN 304 million cubic meters), Nam Ngum 1 (LAO, 300 million cubic meters), Nam Ngiep 1 (LAO, 137 million cubic meters), and Nam Theun 2 (LAO, 143 million cubic meters), Theun Hinboun Expansion (171 million cubic meters), Ubol Ratana (THA, 248 million cubic meters), Yali Falls (VNM, 139 million cubic meters). These restrictions have a devastating effect on the Mekong’s fisheries and agricultural outputs, which rely on high river levels throughout the wet season.

Most Impactful Dams

River Levels River levels along the Thai-Lao border are receding to below normal levels after high from extreme precipitation in August. River levels in Cambodia are increasing from upstream flooding. River levels in northern Laos and Thailand could increase at the end of the week as a result of an incoming tropical storm.

Chiang Saen Gauge Stung Treng Gauge

Weather & Wetness Most of the Mekong Basin is falling into extreme wet season drought conditions (red and orange). A few areas of isolated extreme wetness (blue) are likely the result of recent storms.