“The proposal to prevent flooding by storing underground water in stadiums and schools is absurd”

According to expert Dao Ngoc Nghiem, measures to prevent flooding in Hanoi must take into account compliance with the approved underground planning. “Recently, there was an opinion that storing underground water in schools and stadiums is absurd. In addition to the concern of encroaching on underground space, it is also related to the factors of use and longevity of the aforementioned works,” he said. Nghiem said.

Regarding the problem of flooding in Hanoi when it rains heavily recently, talking to reporter Tien Phong, architect Dao Ngoc Nghiem – former Director of Hanoi Department of Planning and Economics said that there are many reasons.

First of all, the objective causes are abnormal weather changes, continuous heavy rain, and a lot of water. In particular, the rain at the end of May was determined to be the largest in the past 36 years.

Flooding in Hanoi during heavy rain. Photo: Duy Pham

The subjective reason, according to Mr. Nghiem, is that Hanoi’s drainage planning is currently only calculating to meet the rainfall of about 310mm within 2 days. Before the phenomenon of unusually heavy rain as in the past time, Hanoi needs to calculate and adjust this plan.

Mr. Nghiem said that to adjust this plan, it is necessary to combine many measures. First of all, the system of canals, ditches and underground culverts must be cleared and maintained regularly.

“Hanoi has made two times of planning, but the proportion of water surface (for drainage) on the ground is still low. In the whole of Hanoi, only about 2% of the area has water surface for this work, while That said, to ensure regulation, it needs 5 – 6%. Currently, Hanoi has more than 6,000 ha, it must be doubled, to 12,000 – 15,000 ha”, Mr. Nghiem said.

Another measure, according to Mr. Nghiem, is that Hanoi is divided into 4 areas at the end of the drainage source, and must focus on investing in lakes in this area. For example, in the areas of Lien Mac and Yen So, there must be a lake large enough to store water and clean, with properties like a hydroelectric dam, flowing into a large river…

Along with that, it is necessary to increase the capacity of pumping stations against waterlogging and flooding. Currently, Hanoi has many fixed pumping stations and downstream pumping stations, but all of them have a small capacity that cannot be met. Notably, many pumping stations have not been completed or completed, not counting the large amount of rainwater.

Regarding many opinions that Hanoi has filled a number of natural lakes, putting pressure on drainage, Nghiem said that Hanoi has planned green trees and water surface, but has not yet mobilized resources. performance force. In Yen So, there is a large lake to regulate, but it is not possible to dig deep, while some lakes are filled up.

“In the past few years, Hanoi has filled up more than two dozen lakes. Of course there are lakes in residential areas, dead lakes can’t be connected. But the new lake area is in the park, then some lakes. If the old one is renovated, the standing embankment will also reduce the area, then there is no maintenance, the depth to store water is not guaranteed, like the lake in the Youth Park,” Mr. Nghiem stated.

Former director of the Hanoi Department of Planning and Economics said that to solve the above problems, it takes time and capital. The immediate solution is to invest budget to solve local flooding with new technology. Lessons learned from Ho Chi Minh City, some countries around the world have done, such as investing in pumping stations with new technology, and even some water can treat seawater inundation…

“The management agency has to regularly maintain and regularly maintain the system, basically cleaning the canals and sewers. Mobilizing people to limit littering, because when the waste flows down the clogged drains, it cannot escape. water is available, especially in inner-city areas,” Nghiem said.

Before some comments that Hanoi should build some underground tanks to prevent flooding during heavy rain, Nghiem said, the most important thing is to store surface water. Hanoi also has a master plan for underground space, which is a very valuable resource of the city. This plan must be strictly adhered to.

“Like just now, there was an opinion that storing underground water in stadiums and schools is unreasonable. It may violate the planning of underground space, moreover, it will affect the usage factors and the lifespan of buildings. this program”, Mr. Nghiem stated.

Nghiem also said that in the underground planning of Hanoi, there are also underground water tanks, it is important to have resources to do it, such as near the West Lake area, there is also a plan for groundwater storage area. to replenish water for West Lake when needed, and then do many other things.

In short, according to Mr. Nghiem, the problem of solving flooding in Hanoi today is due to “not yet synchronized”. Even the clearing and dredging of the Lu, Set and Kim Nguu rivers has not been completed yet…