The underground river under the auxiliary dam of Mong village irrigation is a karst cave.

(Baonghean.vn) - The phenomenon of abnormal water flow in the Chau Binh auxiliary dam drainage channel is not an underground river but a karst cave phenomenon, which was discovered before and is under the control of the authorities.

On September 8, Nghe An Electronic Newspaper published an article“Underground river discovered under the largest irrigation dam in North Central Vietnam”. The Chau Binh auxiliary dam drainage canal project, part of the larger Ban Mong irrigation and hydropower project, is showing many unusual signs. Locals believe that there is an underground river with strong water flow. Nghe An Newspaper discussed with relevant authorities to clarify this issue.

Mr. Dinh Tri Lam, Deputy Manager of Mong Village Reservoir Project.

Mr. Dinh Tri Lam, Deputy Manager of the Mong Reservoir Project, said: Mong Reservoir is a key irrigation project of the province, built in two communes: Chau Binh (Quy Chau) and Yen Hop (Quy Hop), with a total investment of nearly 4,500 billion VND. This project provides irrigation water for 18,871 hectares along the Hieu River, of which 2,713 hectares are self-flowing, supplying water to the Ca River in the dry season at about 22m³/s.

Explaining the problem of water flowing down the ditch, Mr. Dinh Tri Lam said: During the design survey, some locations with karst caves were discovered. According to the design, water from the drainage canal would flow into the Hieu River, but the water flowed down the karst caves and not into the Hieu River.

This is just a geological phenomenon that does not affect the construction project. During the design survey, we have calculated and anticipated these events.

Furthermore, since this is a drainage canal, there is no need to repair the karst cave. If in the future the Chau Binh drainage canal is used for irrigation, the leaks down to the karst cave can be filled in. Saying that there is an underground river below is unfounded. This requires the involvement of scientists.

Mr. Nguyen Nhu Dung, technical officer of Infrastructure Design Consulting Joint Stock Company - Head of the design consulting project of Ban Mong irrigation project added: During the geological survey to design Chau Binh drainage canal, no karst caves were discovered, because the borehole was not deep enough (according to the design, it was only drilled 2-3 meters deeper than the canal bed), so 40 drill holes were organized/8.1 km of Chau Binh drainage canal.

There are 3 locations of stove caves discovered at 3 bridge construction sites on Chau Binh drainage canal.

Next, during the geological survey to design 6 bridges on the Chau Binh drainage canal, the consulting unit discovered 3 locations with sand caves, of which 2 caves were dry and 1 cave had water. To overcome the above situation, the following solutions must be implemented: First, it is known that the entrance of the sand cave is the water flowing down. The problem is to find the entrance of the cave, in fact, it is very difficult to find the entrance of the sand cave, this cave can run zigzag to pour water into a stream or Hieu River, or it can run back into a cave in a mountain and then flow into the river. Therefore, it is necessary to organize deeper exploration drilling to make an overall assessment and find the exit of the sand cave for treatment.

Some locations in Chau Binh drainage canal discovered sand caves.

Mr. Nguyen Quang Hoa, Director of Nghe An Center for Application and Science and Technology of Irrigation, said: Before constructing the Ban Mong irrigation project, the Ministry of Agriculture assigned the University of Irrigation to be responsible for surveying and evaluating the geology of the routes of this project, especially being wary of karst caves, because of the mountainous area. The issue of discovering karst caves during the construction of this project is under the control of the relevant sector.

Mr. Hoang Nghia Hieu, Director of the Department of Agriculture and Rural Development, said: Regarding the construction of Chau Binh drainage canal, we know that the geological layer has local sand caves. Therefore, during the construction of the bridges, including 3 bridges with sand caves, we directed the construction unit to drive concrete piles to ensure the quality of the project. Currently, we are continuing to survey and inspect to have safe handling measures for this project.

Van Truong