The sand has caused big changes in the delta. It has appeared on large roads, near high-rise buildings in urban areas and houses in rural areas. It is part of huge construction works such as My Thuan Bridge and Tra Noc Airport. It is present in people’s daily life and activities, from leisure, recreation to religion.

Alluvium comprises inorganic and organic materials which have different sizes, from rock, gravel, to coarse sand and fine sand, from rich soil and clay to disintegrated organic materials and water-soluble substances.

There are different sections on a river, including one that creates alluvium, one that creates temporary sediment, and another that creates permanent sedimentation. 

In general, the alluvium creating area is in the upper course, while the temporary sediment area is in the middle and the permanent sediment area is in the delta.

As for the Mekong River, the first section is located in China and Myanmar territory, the second in Thailand, Laos and Cambodia, and the third in Mekong River Delta, of which 20 percent is in Cambodian territory and 80 percent in Vietnam.

Regarding the coarse and fine sand, 80 percent is “produced” in China and Myanmar, while 15 percent in Thailand and Laos, and the remaining in the upper course of the Sesan, Sekong and Serepok rivers.

Because of the geographical structure, there are thousands of deep holes at the bottom of Mekong River’s section which runs across the territories of Thailand, Laos and Cambodia. The deep holes contain baskets, with hundreds of thousands of cubic meters of sand in each.

With the current natural sedimentation, it takes several to tens of years for the river to bring sand to Vietnam’s Mekong River Delta.

As China builds hydropower dams, 50 percent of the volume of sand created every year cannot move to Thailand and Laos, while the remaining is exploited by the three countries for their economic development.

The reports released recently all showed that the solid content in alluvium, including rock, gravel, coarse sand and fine sand, that move to Thailand and Laos have decreased from 100 million tons to 50 million tons. Meanwhile, the content of heavy earth, clay, disintegrated organic substances and soluble substances has also decreased from 70 million tons to 10 million.

Meanwhile, the amount of gravel and sand exploited by Thailand, Laos and Cambodia has far exceeded the 50 million ton threshold. Since 2010, sand is no longer moving to Vietnam’s Mekong River Delta.

TBKTSG