MRC Sees ‘Critical Situation’ as Reverse Mekong Flow into Tonle Sap Delayed
AKP Phnom Penh, July 28, 2020 --

The Mekong River Commission (MRC) warned Tuesday that the delayed reversal of the Tonle Sap River could adversely affect fish spawning and agricultural production.

In a weekly situation report, the MRC’s Regional Flood and Drought Management Centre in Phnom Penh said water levels were below long-term averages in Stung Treng, Kratie, Kampong Cham and Neak Luong on the Mekong River.

Water levels at Chaktomuk and Koh Khel on the Bassac River and at Phnom Penh Port and Prekdam on the Tonle Sap River were also below their long-term averages.

As of Monday, the annual reversal of the Tonle Sap River — caused by the volume of water flowing downstream along the Mekong — had “not happened yet,” the report said.

Low inflows from the Mekong and less rainfall in sub-catchments around the Tonle Sap could be the reason for the “critical situation” of the lake, it said.

“More than half of the annual inflow to the lake originates from the Mekong mainstream,” the report said.

“Thus, flow alterations in the mainstream would have direct impacts on the Tonle Sap water levels and hydrology,” it added.

"The low volume flow of the Tonle Sap Lake could affect the surrounding floodplain for fish spawning in the flooded forest,” the report said.

It could also lead to a "water shortage for agricultural production" in the area.

The center said lower water levels along the Mekong mainstream in June and July reflected “less rainfall” from catchments and a prolonged El Nino phenomenon.

At the same time, low inflows from upstream since June reflected “reservoir operation and water retention from upstream on the mainstream and tributaries.”

The report noted that tributaries in central Laos along with those in southern Laos and northern Cambodia accounted for more than 40 percent of Mekong flows. China contributes about 16 percent of the flows, it said.

By Sao Da
AKP

As the Mekong delta washes away, homes and highways are being lost
Upstream dams are blocking the sediment that nourishes the Mekong delta, while erosion and sand miners take what remains
Michael Tatarski
March 10, 2021

One night two years ago, Lam Thi Le and Nguyen Van Thuong heard loud cracks coming from their neighbours’ riverfront home. The neighbours left, and a day later half of their house collapsed into the broad Tien River as the land beneath it slid away.

The shell of the remaining half sits precariously on the jagged river bank. Le and Thuong live a few metres inland. Nearby, workers use a machine to pack rocks onto the riverbank, laying the foundation for a concrete embankment designed to prevent further erosion.

This community in Vietnam’s Dong Thap province is not unique. The Tien is one of the Mekong River’s main branches flowing down from Cambodia’s capital Phnom Penh. In recent years, dams built upstream in China, Laos and Cambodia and local sand mining have starved delta provinces such as Dong Thap of sediment, causing once-stable land to erode.
With upstream dams cutting off the flow of sediment, and rampant sand mining in both Vietnam and Cambodia, once stable land on the Mekong delta is now being washed away.

The Mekong’s average sediment load used to be 160 million tonnes, according to Marc Goichot, WWF’s Lead for Freshwater in the Asia Pacific, but the construction of dams on the river has reduced this by almost 80%.

“Dams and sand mining are working in a cumulative manner,” Goichot said. “Sand mining is making the impact of dams not only worse but much faster. We know that the impacts of the Aswan dam in Egypt took 50 years to reach the Nile River delta, and in the Mekong it’s much faster.”

Vietnam’s agriculture ministry estimates that the delta, which produces much of the country’s rice, aquacultural goods and fruit, worth billions of US dollars, loses 500 hectares of land per year to erosion.
https://chinadialogue.net/en/energy/as- ... eing-lost/