Urgently complete anti-erosion embankment in Nam Cuong (Nam Dan)

(Baonghean) -Lam River, section through Nam Cuong commune, districtMaleThe flood caused erosion of dozens of hectares of land. Local people said that the current riverbed was a prosperous and crowded village decades ago. The landslide forced the village to move inside the dike. A few years ago, the railway industry also built a system of embankments to prevent landslides using concrete piles, but it still could not prevent landslides.

According to Mr. Dinh Xuan Que, Vice Chairman of Nam Dan District People's Committee, the landslide rate is increasing, along a 2 km long riverbank, after each flood season the river soil moves a few dozen meters inland. Faced with the threat to the North-South railway (the river is only a few dozen meters away from the nearest section) and thousands of people in Nam Cuong commune without land for production, in 2008 the district launched the project "anti-erosion embankment of Lam river bank through Nam Cuong commune", with a total investment of nearly 24 billion VND (now with the increase in price, it has increased to nearly 30 billion).



Construction of embankment to prevent landslides in Nam Cuong (Nam Dan).

In 2011, 5 billion was allocated, in 2012, 2 billion was allocated from the Government's anti-landslide fund, plus 1 billion from the province's excess revenue. With less than 1/3 of the capital, the districtMaleThe group is still determined to construct the project, because every day of delay means losing more land.

In Mr. Que's humorous way of saying it, this isMaleThe flock “breaks the fence”. According to Resolution 11, the construction works under construction are carried out according to the capital available. This cannot be applied to river embankments, they must be completed before the flood season, otherwise they must be redone from the beginning next year.

Currently, after 4 months of construction, the project has been basically completed, the construction units are striving to hand over the project before the flood season. During the rainy season, we visited the project, Mr. Thai Doan Bon - Team leader in charge of construction of Viet Lao Company, said: The total length of the entire route is 1.83 km, divided into 5 packages, Viet Lao Company is in charge of 1 package. Construction started on March 16, so far 2/3 of the work has been completed. To prevent the flow of erosion of the bank, the contractor must create a "wall" to prevent water from contacting the bank soil. The wall here is designed: From the bottom of the river to the riverbed canvas is covered with a layer of stone gabions. Next is a 2m concrete footpath, stabilizing the stone gabions, and at the same time serving as a support for the foot of the revetment. The revetment roof is designed with a concrete frame, divided into independent cells, the bottom of the cells is covered with a layer of soft geotextile to keep sand and soil from flowing through. The top is made of rubble, the 2m wide embankment surface is poured with concrete. With this design, from the river bottom to the embankment surface is a continuous block that prevents water from eroding into the earthen bank. According to Mr. Bon, this method has proven effective, the construction sections 2 months ago saw sedimentation of mud. According to calculations, after about 2 years, this sedimentation layer will become a hard bank.

However, when talking with Mr. Bon and Mr. Que, both of them had a common concern: the indiscriminate sand mining on the Lam River is one of the reasons leading to the river changing its course and deforming the riverbed. One day, when the project is completed, the current indiscriminate and unplanned sand mining will not be able to guarantee the nearly 2 km of stone mats spread on the riverbed. The authorities need to investigate, plan and license the sand mining area on the Lam River, only then can the project be protected in a sustainable way.

Cong Sang