Alert: 02/22/2025
A sudden release of water at dams in China will cause the Mekong River to rise 0.50 meters at Chiang Saen, Thailand on February 24.
Spotlight
August flow would have been much higher than normal without dam impacts.
A major weather pattern over the Mekong in mid-August brought increased river levels to higher than normal through the river system for multiple days. Flooding observed was observed in some areas of the lower basin. If not for the impacts of dams, flow would have been much higher for a sustained period. At Chiang Saen, dam restrictions in China reduced flow from above normal levels to below normal. At Nakhon Phanom, rainfall in northern Laos caused the river to flow at high volumes even with the impacts of dams. Further downstream in the 3S Basin, low rainfall and cumulative dam restrictions upstream brought the river back down to normal levels at Stung Treng. Normal and high river levels are important drivers of the Mekong Floodpulse.
What Happened Last Week?
- Where’s the Water: Last week saw an insignificant net restriction of water (313 million cubic meters). Major dam restrictions were offset by releases at some dams. Major restrictions were observed at Xiaowan (PRC, 327 million cubic meters) and Nam Ou 7 (LAO, 285 million cubic meters). These were offset by a major release at Huangdeng (PRC, 423 million cubic meters). Where is the water?
- River Levels: Levels along the Mekong are near normal for this time of year as a pulse of water moves through the system over the next two weeks. See how this looks.
- Where’s the Water: Last week saw an insignificant net restriction of water (313 million cubic meters). Major dam restrictions were offset by releases at some dams. Major restrictions were observed at Xiaowan (PRC, 327 million cubic meters) and Nam Ou 7 (LAO, 285 million cubic meters). These were offset by a major release at Huangdeng (PRC, 423 million cubic meters). Where is the water?
Image of the Week
Despite improvements in the Mekong Floodpulse, more water is needed to drive Tonle Sap expansion.
From late July to late August, the Mekong Floodpulse increased by nearly 2,000 square kilometers, yet the Tonle Sap expansion remains relatively weak due to low lake levels. Lake levels stayed very low into the first two months of the wet season requiring more water than usual to drive a robust expansion of the lake. Currently, natural and normal Mekong flooding upstream of Phnom Penh is spilling over into the Tonle Sap watershed bringing with it one of the best reverse flow trends we’ve seen since 2019. This year is on track for a normal volume of reverse flow into the Tonle Sap Lake. With residual low lake levels, this means that the level of fish eggs and organic material flowing into the lake during the wet season will be somewhat normal, but there will be less habitat for the fish to thrive. There is still time for the Tonle Sap Lake to expand another large pulse of water works its way through the Mekong. We predict a decently robust fish catch for the Tonle Sap this year, and more rains will bring more fish.
Where is the Water?
How Wet is the Mekong Basin?
- Click or hover over icons on map for more details.
How Much Water is in Reservoirs by Country?
Current volume (billion cubic meters) of usable water across the 45 largest reservoirs in the Mekong Basin.
How Much Water is in the Largest Reservoirs?
- Hover over chart to track reservoir volume for any particular week during the year.
How Strong is the Floodpulse?
Where did River Flow Come From?
How Wet is the Mekong Floodplain?
What Should River Levels Be?
Chiang Saen Gauge (Thailand) [UNDER MAINTENANCE]
Stung Treng Gauge (Cambodia)
Chau Doc Gauge (Vietnam)
For more info, click Natural River Flow Models in the top menu.
How do Dams Impact Different Points along the Mainstream?
How was the Weather Last Week?
- Click on maps to expand and for more details.
For more information, click Compare Maps and Data in the top menu.
Which Dams Impacted the Most?
- Click or hover over icons on map for more details.
Reservoirs with an estimated change of more than 50 million cubic meters (m³) of water over last 7 days.
For more info, click Virtual Gauges in the top menu.
Current Reservoir Volume for 58 Dams
- Hover over reservoir bars to see current or potential volume
For more info, click Virtual Gauges in the top menu.