The Mekong is once again at historical lows. The Mekong River Commission (MRC) gauge at Phnom Penh Port shows river level to be four metres below average for this time of year – and lower than last year’s record.
This gauge is measuring river level on the Tonle Sap River just a few hundred metres upstream from the Tonle Sap’s confluence with the Mekong mainstream. This river level indicates the annual reversal of the Tonle Sap River and flooding around the Tonle Sap lake will happen much later than expected, tweeted Brian Eyler, a senior fellow and director of Stimson’s Southeast Asia programme.
He went on to say: “The causal factors are a lack of rainfall, the Mekong’s wet season has yet to kick in and the impacts of hundreds of upstream dams in Laos (100+), Cambodia (two), Thailand (nine+), Vietnam (16+), and China (100+). China’s major upstream dams at Nuozhadu and Xiaowan have already turned off their taps and are in the process of restricting around 20 billion cubic metres of water – at a time when the downstream needs that water.
Thousands of families in Cambodia rely on the Mekong for a variety of work.
“Confirming earlier reports of the #Mekong again at record lows, today’s @MRCMekong data show river level at Phnom Penh Port (along the Tonle Sap River) to be at a historical low. 4m below average! At this level, the 2020 reversal of the Tonle Sap will be super-late,” said Eyler.
The MRC is the only inter-governmental organisation that works directly with the governments of Cambodia, Lao PDR, Thailand and Vietnam to jointly manage the shared water resources and the sustainable development of the Mekong River.
As a regional facilitating and advisory body governed by water and environment ministers of the four countries, the MRC ensures the efficient and mutually beneficial development of the Mekong River while minimising the potentially harmful effects on the people and the environment in the Lower Mekong Basin.
The Thomson Trust Foundation said water typically flows into the Tonle Sap lake for 120 days, swelling it six-fold before running back into the Mekong as the monsoon season ends, usually in late September. Based on rain forecasts and rainfall data, the river’s unique reverse flow should happen in August, said Long Saravuth, a deputy secretary-general of Cambodia’s National Mekong Committee.
The Mekong contributes to Cambodia’s unique river system. In the dry season, the Tonle Sap flows into the Mekong where the two rivers meet in Phnom Penh. This reversal in flow of the Tonle Sap and the related flooding helps support Cambodia’s wildlife, rice farming and even the stability of the Angkor Temple foundations.