Every year, 55 million tons of sediment is lost from the rivers in Mekong Delta, 90 percent of which is sand. Nguyen Huu Thien, an independent expert, said the Mekong Delta has been taking shape for the last 6,000 years thanks to alluvial accretion. But the volume of sediment in the river and canal system has decreased gradually, leading to an increased risk of landslides.
The coastal provinces in the western part of the southern region are also directly affected by the change. The alluvium from river mouths to the sea has the function of protecting the coast, easing the impact from waves hitting the coast. When there is not enough silt, the sea water will cause erosion.
Therefore, according to Thien, it is necessary to re-establish control over land exploitation to prevent the loss of natural resources. Research also points out the high risks that the Mekong River Delta is facing.
A survey by the Mekong River Commission (MRC) found that in 1992-2014, the amount of suspended sediment in Mekong River valley decreased from 160 million tons to 75 million tons per annum.
According to Marc Goichot, an energy and hydropower expert from WWF, the sediment depletion has relations with sand mining and construction of dams upstream of the Mekong river.