Biased data updated after apparent errors revealed in US-funded project's monitoring against Chinese dams on Mekong River
Published: Mar 03, 2022 08:50 PM
Lancang River in Southwest China's Yunnan Photo: VCG

Lancang River in Southwest China's Yunnan Photo: VCG

The US-funded platform "Mekong Dam Monitor (MDM)" corrected its released data errors on water level readings of Chinese reservoirs on upstream Mekong River, which is called the Lancang River in China, soon after the Global Times' report on Wednesday, citing the Chinese scientists pointed out its serious flaws.

Chinese hydrological experts from Tsinghua University discovered that the reservoir level readings released by MDM contained serious errors and differed significantly from the actual gauge, which can easily be misused in the hyping of Chinese dams "controlling water" and "hurting downstream countries." 

MDM monitored the hydrological and climactic information of all China's 11 dams on the Lancang  mainstream from December of 2020. Observers said errors were partly caused by backward tools and backdoor political considerations.

In its latest Facebook post on Wednesday, the MDM recognized some errors, including a serious "typo" in their data, and made corrections after their double check using a high-resolution satellite imagery from a professional platform Planet Labs.

A comparison diagram of water level reading of Xiaowan Reservoir given by Tsinghua scientists. Photo: Research team of Tsinghua University

A comparison diagram of water level reading of Xiaowan Reservoir given by Tsinghua scientists. Photo: Research team of Tsinghua University

"Many thanks to a research team from Tsinghua University in China for pointing out a few possible directional errors on the 2020 operation curve for Xiaowan as determined by our virtual gauge process," said the post.

Chinese hydrological research team found that the data obtained by MDM's satellite remote measurements reverses the actual water level rise and fall trends of Xiaowan Reservoir at least in three monitoring periods in 2020, with errors up to 14.84 meters, which is equivalent to some 2.4 billion cubic meters of water.

Even after the revision, MDM's reading still has an error of up to eight meters from the actual water level measurement, for example at the time point of April 8, 2020, experts from Tsinghua University told the Global Times on Thursday.

Chinese experts cautioned that the errors could be misinterpreted as "Chinese dams intercepting water" and be negatively hyped as evidence that "upstream dams are causing drought downstream."

"An error of eight meters is roughly 1.2 billion cubic meters of water. The impacts for some downstream countries are obvious and worrisome," said the research team.

Despite of significant partial deviation, the revised MDM's data can reflect the rough overall trend of Xiaowan Reservoir's water level changes, as the MDM said.

MDM calls for Chinese scientists to share more information about Lancang reservoir levels in its Facebook post, but actually China has published its reservoirs' daily overall water release to downstream since November 2020, and has insisted on reporting annual water discharge and relevant hydrological information to riparian countries.

China and countries of the lower Mekong River have teamed up for their largest joint study on hydrological and climate changes, to find out best solutions to cope with the increasing natural threats. 

In September 2021, the Mekong River Commission -an intergovernmental body comprising Cambodia, Laos, Thailand and Vietnam -announced a three-year study spanning the entire river basin, in tandem with Myanmar and the China-led Lancang-Mekong Cooperation Water Center, VOA reported.