Four Mekong river provinces face rising water as super El Niño approaches

Rapidly rising Mekong water levels increase the threat of flooding, as forecasters warn that one of the strongest El Niño events on record could bring greater heat and water shortages later in the year.

Cambodian authorities have warned communities along the Mekong to prepare for further rises over the coming days. Kiripost reported that four river provinces face sharply increasing water levels over a three-to-four-day period, while a separate report citing the Ministry of Water Resources and Meteorology specifically identified Stung Treng, Kratie and Kampong Cham as areas where Mekong flooding is expected to continue rising.

The situation is already becoming serious in Kratie. Provincial figures showed the Mekong at 21.37 metres at 7am on August 21, only 0.63 metres below the province's 22-metre warning level. On August 12, the river had stood at 19.34 metres, meaning it had risen by just over two metres in nine days. Authorities have reported flooding of rice crops in parts of Chet Borei district and Kratie city, while a primary school in Dar commune was also inundated.

Kiripost attributed the latest expected rise to weather associated with Typhoon Saudel, although Cambodian authorities have stressed that the country is not directly in the storm's projected path. The wider Mekong region has nevertheless experienced substantial monsoon rainfall and repeated tropical weather systems this month. Earlier in August, Cambodia's water ministry warned that Tropical Storm Kujira and Typhoon Dolphin would strengthen the south-west monsoon, bringing widespread rain across much of the country.

The more important question for Cambodia, however, could be what comes after the current flood threat. The El Niño is strengthening rapidly in the tropical Pacific. The World Meteorological Organization said at the end of July that a strong event was developing and would intensify during August to October, while NOAA's August assessment put the probability of a very strong El Niño during the northern hemisphere autumn and winter at above 90%. NOAA also estimated a 69% chance that the event could reach a level exceeding all previous El Niños in its records dating back to 1950.

For Cambodia, that creates the prospect of a sharp transition from too much water to too little. The ASEAN Specialised Meteorological Centre expects below-normal rainfall across much of Southeast Asia during August to October as El Niño strengthens, alongside above-normal temperatures. Strong El Niño conditions can increase the likelihood of prolonged dry periods.

Cambodian officials are already preparing for that possibility. Water Resources Minister Thor Chetha instructed officials in July to conserve as much water as possible during the middle and latter parts of the rainy season specifically to guard against water shortages and higher temperatures during the coming dry season as El Niño intensifies.

The consequences could extend beyond irrigation and drinking-water supplies. Previous low-flow periods in the Mekong have reduced the volume of water reversing into the Tonle Sap during the wet season, disrupting the lake's flood pulse and affecting fish habitats and catches. An Mekong River Commission study concluded that unusually low rainfall was the main driver of the severe Mekong low flows of 2019-21 and linked the rainfall pattern partly to El Niño.

Cambodia therefore faces two very different climate risks in succession. In the immediate term, authorities must protect river communities, crops and infrastructure from rising Mekong waters. Over the coming months, the challenge could reverse: capturing enough of this year's wet-season water to withstand a potentially exceptionally hot and dry El Niño-influenced dry season extending into 2027.