At the workshop to collect opinions to complete the Project on handling flooding in inner Hanoi areas in the period 2026-2030, on March 25, many experts emphasized the necessity of synchronous, comprehensive and long-term solutions.
Director of Hanoi City Technical Infrastructure Management Center Nguyen Duc Hung said that the project aims to improve the capacity of the entire urban drainage system, ensure traffic safety, stabilize people's lives and improve the living environment. Based on current data, the consulting unit analyzed the causes, calculated the hydraulic model, and then proposed engineering and non-engineering solutions, along with the list of investment projects for the 2026-2030 period.
The project also expands the scope of research to other basins to ensure synchronicity and conformity with the 100-year vision of the Capital Development Plan.
Currently, among the 4 main drainage basins of Hanoi, only the To Lich River basin has been relatively completely invested. The regulating lake system has only reached less than 20% according to the plan; the main pumping stations also only reach about 20% capacity. The entire system still heavily depends on the Yen So pumping station with a capacity of about 90m3/second.
According to Director of Hanoi Department of Construction Nguyen Phi Thuong, the investment in drainage infrastructure has not kept up with the pace of urbanization, along with limitations in managing construction site elevation, causing flooding to occur in many areas when there are heavy rains.
In the context that Hanoi City is completing the Overall Plan of the Capital with a long-term vision, drainage planning is also oriented to both solve urgent immediate problems and build long-term response scenarios. Notably, there is an orientation for adaptive urban development, including the "sponge city" model to increase the ability to absorb, store and drain natural water.
According to the consulting unit, the solution system needs to combine construction (gray solution) and non-construction (green solution), approaching according to the basin and operating uniformly.
Regarding works, it is necessary to renovate and upgrade the sewer network; supplement and improve the efficiency of regulating lakes; increase the capacity of pumping stations; and complete the system of canals and ditches according to the plan.
Regarding non-construction works, it is necessary to strengthen maintenance and improve the inter-sectoral coordination mechanism, especially between urban drainage and irrigation; build a database and gradually form an operation center in real time.
Contributing opinions to the project, Dr. Tran Anh Tuan - Vice Chairman of the Vietnam Water Supply and Drainage Association - said that it is necessary to clearly distinguish between "submersion" and "flooding". In which, flooding is caused by heavy rain that cannot drain in time, and flooding is caused by rising river water. Therefore, Hanoi needs to simultaneously implement two groups of corresponding solutions.
Mr. Tuan proposed to supplement a detailed map of flood prevention planning, accompanied by specific data for comprehensive assessment. At the same time, it is necessary to build buffer zones allowing temporary flooding when heavy rain occurs such as stadiums and green areas. Solutions also need to be divided by area: where there is land fund, build regulating lakes; urban areas need to control the rate of concretization; new projects must increase the area of water seepage.
In addition, it is necessary to supplement a map of the entire city's ground elevation to determine the direction of rainwater flow, as a basis for proposing detailed solutions.
Dr. Hoang Thai Dai - representative of the Vietnam Irrigation Association - said that the project needs to consider extreme rain scenarios, and at the same time link urban drainage systems with agricultural drainage systems. Building comprehensive scenarios and urbanization speed will help more accurately assess the impact on water drainage capacity.
According to Prof. Dr. Nguyen Viet Anh, it is necessary to update recent rainfall data to have accurate assessments, especially at localized flooding points. At the same time, it is necessary to develop response scenarios for rains exceeding control capacity, phase investment in accordance with resources and improve inter-sectoral operation efficiency.
Professor Le Van Nghi said that the rain intensity in calculations is still low, and it is necessary to choose a more suitable model. The sewer system needs to be designed with large dimensions, combining water leading and storage functions. Lowering the water level of inner-city rivers also contributes to creating more water storage space when heavy rain occurs.
