Early renovation of lakes and dams to serve natural disaster prevention and control

Faced with some shortcomings that are not suitable to current reality and the damage and degradation of many lake and dam projects, Da Nang city is allocating local budget and coordinating with the Ministry of Agriculture and Environment to propose the Government to support the early renovation, upgrading, and new investment in a number of irrigation projects to serve natural disaster prevention and control and ensure water supply for daily life and production.

An Trach dam is causing a difference in flood water levels between upstream and downstream after more than 25 years of construction. It needs to be replaced with a new, modern, multi-purpose project soon. Photo: HOANG HIEP

Dam damaged, inadequate

In fact, during the floods of many years, the An Trach dam (Hoa Tien commune) caused a difference in water level of Yen river (downstream of Vu Gia river) between the upstream and downstream of the dam. The reason is that the project was designed in an old style and was built 25 years ago with large pillars, so it is outdated and no longer suitable for extreme natural disasters and climate change. On the other hand, the valve compartments also cause blockage and garbage congestion in the upstream, which not only hinders flood drainage but also easily endangers the safety of the project.

General Director of Dak Mi Hydropower Joint Stock Company Vu ​​Duc Khanh said that there is a huge difference in flood water levels between upstream and downstream. The technical specifications of An Trach dam have 12 gates with a designed flood discharge capacity of only 1,447m3/s, so the flood discharge capacity downstream is much lower than the flood flow on Vu Gia river. In addition, according to observations during floods, a huge amount of garbage flows into An Trach dam, blocking the valve compartments, limiting the flood discharge capacity and threatening the safety of the project.

A large aquaculture cage drifted and got stuck in the spillway of An Trach dam during the flood in mid-June 2025, blocking flood drainage. Photo: HOANG HIEP

Recently, on October 27, the military force was mobilized to clear the amount of garbage stuck in the An Trach dam, but on October 29 and 30, the amount of garbage stuck in this dam was very large... To minimize damage and flooding for the downstream area, in addition to flood regulation from hydroelectric reservoirs, the company requested the authorities to evaluate and have urgent and long-term solutions to increase the ability to discharge floods through the An Trach dam in particular and the entire downstream area of ​​the Vu Gia - Thu Bon river system in general.

According to the Department of Agriculture and Environment, the automatic hydraulic gate system of An Trach dam often has problems during operation; the embankment downstream of the dam has collapsed. At Ha Thanh dam, the concrete dam, traffic bridge, energy dissipation tank... has degraded and cracked; the gate system, pulleys, winches, and gate lifting cables are rusted... The main dam of Duy Thanh saltwater prevention dam has a slight erosion, with a 2cm crack that does not develop; the dam foundation is slightly seeping. The buoy tunnels of Bau Nit and Thanh Quyt dams are damaged and silted, causing the automatic gate opening and closing to be lost.

Proposal to repair and upgrade 11 irrigation lakes

Also according to the Department of Agriculture and Environment, in addition to the above 5 dams, the city also has 92 irrigation lakes (including 24 large reservoirs, 25 medium reservoirs and 33 small reservoirs) and is implementing the construction of 7 new irrigation lakes including: Mo O, Ho Khe, Cha Mai, Suoi Tho, Loc Dai, Phuoc Hoa, Ho Do.

Duy Thanh saltwater intrusion prevention dam project. Photo: HOANG HIEP

Through inspection and assessment of dam safety status during the rainy and stormy season by the Department of Agriculture and Environment, 26 dams of the reservoir were leaking; 13 dams had landslides and slope slides; 7 spillways were cracked; 6 spillways, spillways, and energy dissipation were slightly eroded; 7 spillways had cracks...

Many dams of irrigation reservoirs are damaged and degraded, requiring continued investment in upgrading and repairing to ensure safe operation during the rainy and flood seasons. In addition, it is necessary to be equipped with facilities, management, monitoring, communication equipment and upgrade and repair the management road system...

The Department of Agriculture and Environment has proposed the City People's Committee to allocate funds in the medium-term public investment plan for the period 2026 - 2030 to repair and upgrade 11 reservoirs in order of priority. Including: Vung Tom, Ba Xa, Ho Quoc, Tra Can, Cay Son, Cuu Kien, O O, Khe Bo, Cay Xoay, Hoc Lach, Chan Son with a total estimated cost of about 160 billion VND.

Khe Tan reservoir only has free spillway, so it needs to be repaired, upgraded and have additional flood control gates installed soon to serve flood cutting and reduction operations downstream. Photo: HOANG HIEP

In addition, the Department of Agriculture and Environment has requested the Ministry of Agriculture and Environment and the Department of Irrigation Works Management and Construction to support capital for investment in repairing and upgrading to ensure the safety of the main works of 5 damaged and degraded reservoirs including: Ho Quoc, Vung Tom, Ba Xa, Tra Can, Cay Son in the list of works that need to be upgraded and repaired to ensure the safety of water reservoirs in the shortest time. At the same time, support the installation of operational monitoring systems for water reservoirs in the city.

At a working session with the People's Committee of Da Nang City on the management of dikes, dams and hydropower operations to regulate floods in the city on November 4, a representative of the Department of Irrigation Works Management and Construction requested the city to review upstream areas to study the possibility of proposing the construction of reservoirs to cut and reduce floods and supply water to downstream areas.

For some existing irrigation reservoirs with large capacity and free spillway design and construction, especially Khe Tan reservoir (capacity 56 million cubic meters), it is necessary to propose renovation, upgrading and adding more regulating gates to participate in cutting and reducing floods for downstream areas.

Deputy Minister of Agriculture and Environment Nguyen Hoang Hiep informed that the Ministry will propose the Government to select a number of large irrigation lakes (capacity of 20 million cubic meters or more), first of all, select one lake to add a flood control gate to cut and reduce floods downstream because the large capacity of the lake is very valuable.

The Ministry of Agriculture and Environment will direct, urge and coordinate the completion of procedures to soon start construction of a number of projects in the downstream of Vu Gia - Thu Bon River, especially the construction of water regulation and anti-erosion projects on Quang Hue River; construction of a new An Trach dam and dismantling the old dam, ensuring flood drainage and water supply for daily life and production in the center of Da Nang city.

Source: https://baodanang.vn/som-cai-tao-ho-dap-phuc-vu-phong-chong-thien-tai-3309406.html