In Mekong Delta, scientists have urged local authorities to adjust development plans so as to choose the right treatment and avoid serious consequences.

They pointed out that serious landslides in the delta were caused by sand overexploitation, too many houses on riverbanks, and deep holes in rivers.

Meanwhile, Duong Van Ni from the Can Tho University, a well known expert on Mekong Delta, said the problem lies in the lost volume of sand which cannot be offset by the new sediment.

A big amount of sand has been lost mostly because of hydropower dams in the upper course, which prevent sand from going downstream.

The over-exploitation of sand is also a reason. However, the biggest cause, according to Ni, is the treatment of the rivers and the sea.

The alluvium reaching the delta can be divided into two groups: coarse sediment (sand, gravel, grit), and fine silt (meat, clay). There are natural deep holes In the riverbed, some of which have existed for 1,000 years.

In June and July, the water from the upper course flows strongly towards the delta. The energy of the current brings materials in the deep holes in the upper course to holes in the lower course.

There are about 500 such deep holes in the river sections from the northern part of Laos to Vietnam. This means that sand needs hundreds of years to reach the delta.

While the volume of coarse sediment is on a sharp decrease because of the hydropower dams and sand overexploitation, fine sediment cannot enter fields because of embankment. So it has been drifting into the deep sea. The coastline then suffers from serious landslides.

“The coast is just like armor that protects the delta body. As the armor is torn, the delta's body will become vulnerable,” he explained.

“We have misunderstandings about the ecosystem, and we engage in wrong behaviors,” he commented. “We then blame everything on severe nature. ”

Provincial authorities have to spend a lot of money to build dykes and saltwater prevention works. However, this only ‘gives a false sense of security’ as Ni commented. When people make crude interference into nature, suffering will ensue.

 Chi Mai

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