Mekong Dam Monitor (Update for January 20 - February 2, 2025)

 

Update for January 20 - February 2 Notable changes on the Mekong in the last two weeks. Visit the Monitor home for more, including Burmese, 中文, Khmer, ພາສາລາວ, ไทย, and Tiếng Việt translation.

SPOTLIGHT Mekong Floodpulse above normal for late January The Mekong’s flood retreat into the dry season is back on track with about 8,400 square kilometers of flooding remaining in the Mekong basin. If temperatures are not too hot in the coming months, then dry season agricultural production could be somewhat normal in Cambodia and Vietnam.

Where is the water? Last week dams throughout the basin released a large cumulative total of 1.306 billion cubic meters of water. This is a relatively large number for this time of year, although in certain weeks later in the dry season individual dams, particularly those in China, could release more than this. More than half of the dam releases last week came from Xiaowan (PRC, 765 million cubic meters). Other significant releases came from Nam Ngum 1 (LAO, 155 million cubic meters), Theun Hinboun Expansion (LAO, 109 million cubic meters), and Ubol Ratana (THA, 104 million cubic meters).

Reservoir Storage Over Time

River Levels River levels throughout the basin are slightly higher than normal.

Chiang Saen Gauge Stung Treng Gauge

Weather & Wetness The Mekong’s headwaters were exceptionally wet from snow melt or precipitation last week, and this excess water is causing some dams in China to have net increases to their reservoir storage which is unusual for this time of year. Above average wetness extended through most of the upper basin, while northern Laos was drier than normal for this time of year. The rest of the lower basin was wetter than expected, with the exception of parts of Cambodia.

Mekong Dam Monitor (Update for Jan. 5 - 19, 2025)

 

Update for January 5-19

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 holds steady in early January Seasonal flooding in the Mekong increased slightly from late December to early January at a time when it typically decreases. This could have been caused by unseasonable rainfall. However, an alternative explanation is that the observed water is a result of dry season irrigation, since most of the new water appears in Vietnam’s Mekong Delta. Dry season irrigation season typically begins in early March. Regardless, the Mekong Floodplain is wetter than usual for this time of the year and this bodes well for dry season agriculture in coming months.

Where is the water? Last week dams throughout the basin released a cumulative total of 870 million cubic meters of water. This is a relatively large number for this time of year although in certain weeks later in the dry season individual dams, particularly those in China, will release more than this. Dam releases during the dry season artificially raise the level of the Mekong and cause significant disturbances to natural ecological processes. Major dam releases were observed at Huangdeng (PRC, 252 million cubic meters), Nam Ngum 1 (LAO, 233 million cubic meters), Nam Theun 2 (LAO, 159 million cubic meters), and Ubol Ratana (THA, 170 million cubic meters). A significant restriction of water of 164 million cubic meters occurred at Nuozhadu in China.

Most Impactful Dams

River Levels River levels throughout the basin are slightly higher than normal.

Chiang Saen Gauge Stung Treng Gauge

Weather & Wetness The Mekong’s headwaters are receiving water from snow cover that melts during the day. Above average wetness extended through most of the upper basin, while the Golden Triangle and northern Laos were both drier than normal for this time of the year. The rest of the lower basin was wetter than expected with the exception of parts of Cambodia.

CHÚC MỪNG GIÁNG SINH 2024

VINH DANH THIÊN CHÚA TRÊN TRỜI

BÌNH AN DƯỚI THẾ CHO NGƯỜI THIỆN TÂM

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KÍNH CHÚC QUÝ ĐỘC GIẢ & GIA QUYẾN

MÙA GIÁNG SINH AN LÀNH

 TRÀN ĐẦY HỒNG ÂN THIÊN CHÚA

 

Mekong Dam Monitor (Update for Dec. 2 - 15, 2024)

 

Update for December 2-15

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 2024 Wet Season Dam Restrictions in China: Highest Ever Observed China’s 12 dams restricted more water than ever before during the wet season months of June-November 2024. We tracked a total of 23.1 billion cubic meters of restrictions, slightly higher than 2018’s cumulative restriction of 22.9 billion cubic meters. For the first time in seven years, the Nuozhadu Dam (the largest on the Mekong) filled to full capacity. The dams could fill due to relatively wet conditions in China throughout the wet season. These restrictions reduced roughly 18% of natural wet season flow to Chiang Saen, Thailand, which was relatively low in comparison to previous years given comparatively higher amounts of precipitation this year. In 2019, 2020, and 2021, China’s dams restricted 30% of natural flow to Chiang Saen, Thailand, delivering much more severe negative impacts to the Mekong’s natural floodpulse process and communities downstream. From here onward into 2025, China’s dams will release much of these high reservoir volumes into the downstream, artificially raising the level of the river. In previous years when China’s reservoirs were similarly high, releases for hydropower production have TRIPLED monthly flow to Chiang Saen, Thailand and DOUBLED monthly flow to Stung Treng, Cambodia. Artificially high river levels are extremely damaging to fish migration behaviors and the flooded forest areas along the Mekong River on which local communities rely for food and water security.

IMAGE OF THE WEEK 2024 Wet Season Flow Wetter in the Upstream and Drier in the Downstream The Mekong’s downstream reaches usually contribute more wet season flow than parts of China and northern Laos, but this was not the case in 2024. Combined flow from China, the Golden Triangle, and Northern Laos accounted for 40% of flow at Stung Treng in 2024  (compared to a historical average of around 30% prior to 2007 when dams did not impact natural flow) and flow from northeast Thailand and the 3S Basin accounted for 30% of flow (their combined historical pre-dam average is 40%). Flow contributions in northeast Thailand were particularly low at 10% due to severe drought there. Over the last 15 years, northeast Thailand flow contributions have averaged 20% of flow to Stung Treng. Much of the flow originating in the upstream came from the severe weather events that hit the upper basin in August and September.

Where is the water? Dry season releases for hydropower production have begun and small peaks of water from dam releases are pushing through the Mekong. Last week we observed a cumulative release of 601 million cubic meters of water from 13 dams throughout the Mekong, with the most significant release coming from Nuozhadu (PRC, 496 million cubic meters). These releases artificially raise the level of the river and cause harm to local communities and wetlands.

Most Impactful Dams

River Levels River levels throughout the basin are slightly lower than normal.

Chiang Saen Gauge Stung Treng Gauge

Weather & Wetness Much higher than normal temperatures in the upper basin in China brought rain and extreme wetness instead of snow last week. Most of Laos and Vietnam were also much wetter than normal for this time of year. Conditions were also wetter than usual in most of Thailand and Cambodia, although there was a drier than normal area north of the Tonle Sap Lake near Siem Reap that has persisted for many weeks.

Mekong Dam Monitor (Update for Nov. 25, 2024 - Dec. 1, 2025)

 

Update for November 25 - December 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 Mekong Floodpulse continues its retreat The Mekong floodpulse continues its retreat as the basin transitions from the wet season into the dry season. The current amount of seasonal flooding (14,900 square kilometers) is above average for this time of year. However, the floodpulse peaked one month later than the historical norm this year, and therefore its retreat is about one month late. The Mekong Delta in Vietnam tends to benefit from a late retreat because freshwater is available for agricultural purposes longer into the dry season.

Where is the water? At the end of the wet season, we typically observe a mix of releases and restrictions from dams throughout the Mekong. Restrictions were observed at seven dams with the largest at Nuozhadu (PRC, 168 million cubic meters) and Lower Sesan 2 (CAM, 136 million cubic meters). Releases were observed at fourteen dams with no large releases observed. This resulted in a small net restriction of 193 million cubic meters.

Most Impactful Dams

River Levels River levels throughout the basin are generally near normal. Eyes on Earth estimates that 28% of flow is missing at Chiang Saen, Thailand, as a result of upstream dam restrictions.

Chiang Saen Gauge Stung Treng Gauge

Weather & Wetness The upper basin continued to be extremely wet, creating higher than normal river flow from the Mekong headwaters in China. The lower basin was unusually warm with near normal wetness across most of the region. Most of Cambodia and Vietnam’s delta had above average wetness.