Tonle Sap Lake Runs into Flow Problems

Anoulak Kittikhoun, CEO of the MRC Secretariat, spelled out the issues in his second State of the Mekong Address in the Laos capital Vientiane on April 4. Photo provided

PHNOM PENH – Changing water flow to and from the Tonle Sap lake is among five alarming trends identified by the Mekong River Commission.

Anoulak Kittikhoun, CEO of the MRC Secretariat, spelled out the issues in his second State of the Mekong Address in the Laos capital Vientiane on April 4. His address was part of the Commission Summit, attended by Prime Minister Hun Sen.

Kittikhoun said that despite meaningful progress to better protect Southeast Asia’s largest river, it faces alarming trends in water flow, nourishing sediment, salinity, plastics pollution and climate change-driven flood and drought.

“According to MRC monitoring, the past decade has seen higher dry season flows, but lower flood season flows,” he said.

“This is most pronounced at Tonle Sap – the region’s largest, most productive lake, described as the beating heart of the Mekong. Yet last December, its outflow into the Mekong was one-half its 1995 level.”

A year ago, Kittikhoun sounded the alarm about how four straight years of low flow had created an unprecedented challenge for the Mekong and the vulnerable fishing and farming families who rely on it.

Heavier rainfalls and water-storage releases from upstream brought a brief respite but many hurdles remained.

“Do I have good news this year? The answer is yes and no,” Kittikhoun told hundreds of experts, diplomats, and Mekong university students at the 4th MRC Summit and International Conference.

“In the year 2022, drought may have subsided, and we may have more rain, but the environment still faces several pressing challenges.”

Yet, while the intergovernmental MRC is the leading forum for water diplomacy – on behalf of Cambodia, Lao PDR, Thailand and Vietnam – he urged the audience, “We cannot do everything. Our hope is to inspire all actors, in your respective roles and interests, to complement our efforts, fill our gaps, and/or do what we cannot.”

Kittikhoun described another four troubling trends.

Upstream sediment trapping and sand mining had dramatically reduced sediment loads in some parts by anywhere from 60% and 90%.

“This can impact both floodplain productivity and riverbank stability,” he said. “The Mekong cannot continue to lose sediment, otherwise it will cease to be the Mekong.”

Rising salinity was another concern, with parts of the Mekong delta just two meters above sea level. Salinity concentrations above one gram/litre already have consequences for irrigation.

Yet now the MRC measures concentrations of quadruple that, at 4 gram/litre, on 138 more square kilometers each year. This can spoil rice paddies, Kittikhoun said, with implications for food security and export.”

Fourth was plastics pollution. The Mekong is already estimated to pour into the world’s oceans the 10th-largest amount of plastic debris, anywhere from 17.4 to 101 tonnes per day.

“That’s like the size of a giant whale of waste thrown into the ocean each day,” Kittikoun said. Just as bad were microplastics. Fish can ingest them, which can contaminate the human food chain.

Fifth, how climate change has exacerbated floods and drought. While the number of “heavy rainy days” has dwindled in the Lower Mekong River Basin, when they hit, they hit hard, he said.

In the wet years of 2018 and 2000, “the number of people suffering from floods increased to as many as 12 million.” Meanwhile, drought frequency increased in the 10 years, from 2010 to 2020, compared with the previous decade.

On the brighter side, water quality along the Mekong mainstream remains “Good” or “Excellent” in most places. Socio-economic growth and living standards have increased across the region, especially before the COVID pandemic.

He called for the riparian countries, partners and stakeholders to act.

“The way we choose to act, and the way our friends within the region and without, act, will determine the fate of the Mekong – and all of us,” he said.

At the summit, Hun Sen highlighted the strategic importance of the river as a key supporting source for the sustainable development and growth in Mekong countries as well as for the well-being of the basin peoples.

He said enhanced cooperation and collective efforts among the Mekong countries and with other relevant partners and mechanisms was essential for resilient, sustainable and inclusive development of the Mekong River Basin.

​Cambodia was committed to cooperating fully to bring about greater successes under the MRC framework, the PM said.

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