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Flash floods continue to torment Ha Noi

Update: July, 02/2012 - 09:49

Monsoonal rains are again causing widespread temporary flooding throughout Ha Noi. This disrupts traffic flows and even threatens people's safety. A Viet Nam News reporter discussed the issue with experts and citizens.

What do you think about the flooding in Ha Noi?

Pham Sy Liem, deputy chairman of Viet Nam Construction Association

 

Pham Sy Liem
During the rainy season between May and August, people in Ha Noi have to get ready for floods that force them to always be prepared so that their homes and shops are not swamped.

This year, 21 new flood spots were reported as relevant authorities stated that projects to maintain and improve the drainage systems in central Ha Noi were basically finished. They said lakes and drainage canals had been dredged and other steps taken to solve potential flooding.

About 56 inner-city lakes have been cleaned out and 93 drainage works have been repaired and improved this rainy season.

However, it should remembered that just some areas are inundated, not the whole city. Therefore, it is necessary to find out specific causes for the flooding in each area.

Le Sang, Tay Son Street, Dong Da District

 

Le Sang
Heavy rain on Saturday night woke all my family. Storm water flowed into the house and we had to move furniture to the second floor. The storm water also flooded our fresh water tank, leaving us without water for cooking for a day or so.

A week ago, the most serious rain this rainy season covered the ground floor of our home in 70cm of water. My wife spent five hours trying to get home in the heavy rain and flooding. My children had to stay at their friends' house. The water short-circuited the electricity and the lights went out. It was terrible

Such rains cause troubles for us and other households in our neighbourhood. Although we all are ready to deal with floods year after year, they still frighten us.

What are the main causes for local flooding?

Andre Bilokur, associate director, Archetype Group

I know from my own experience that occasionally the infrastructure in Ha Noi is not sufficient to handle the storm water we sometimes get. As there is so much built-up area in the city, all the storm water goes from the roofs to roads.

Flooding in Ha Noi has been happening for many years. It would be unfair to only blame new projects for this flooding. It should be understood that all buildings constructed here contribute to flooding.

Liem: Some areas of the city have developed too fast, but the drainage systems have failed to catch up. Meanwhile, lakes in areas where most of the storm water escapes to are either full - or have shrunken. All this leads to temporary flooding.

For example, Nguyen Chi Thanh and Pham Huy Thong streets in Ba Dinh District around Ngoc Khanh Lake are usually inundated for several hours when the rainfall exceeds 50mm per day.

The reason is that the storm water from these streets flows into Ngoc Khanh Lake, the lowest point around. However, the lake has been allowed to shrink and storm water cannot be absorbed completely.

Another reason for the flooding is that the My Dinh urban area is built on rice fields, which are lower than surrounding areas. When the foundation of the newest area was raised to a much higher level, this caused flooding to neighbouring areas during heavy rains.

The concrete foundations of streets and buildings cannot be blamed for the floods because Ha Noi has much less of this than other cities in the world which never suffer from flooding.

Sang: Ha Noi did not suffer too many floods 10 years ago because the storm water was absorbed directly into the ground, ran off into the lakes and sewerage systems to the rivers.

Now, concrete streets prevent it from being absorbed to the ground and many lakes are filled with rubbish and water. Meanwhile, sewerage systems do not operate as well as they used to in spite of millions of dong being funnelled into their improvement. These are the reasons for serious flooding.

What are solutions to this issue?

Liem: Firstly, It is necessary for the city's leaders to entrust experts and relevant authorities to work out a comprehensive plan that specifies the causes and solutions to every flood spot.

It is beyond the capability of Ha Noi Sewerage and Drainage Company to solve all the problems.

When all the flood areas are fixed, any organisations or companies that contribute to new flooding will be punished and told to fix the problem.

Another solution would be to provide maps and statistics relating to the height and foundation of streets and areas to serve as a scientific basis for other projects. This would also provide the legal basis for authorities when issuing construction licences.

Finally, the system of sewerage and pumping stations should be improved and built according to a synchronous plan.

Bilokur: I am originally from the United States and we have the US Green Building Council, which defines a series of practices on how we design buildings and how these buildings must integrate with their immediate environments. Storm-water management and water retention are included in the practices.

 

Andre Bilokur
All new construction in some areas is now required by law to handle 100 per cent of storm water on site. This means that no storm water is allowed to run-off along the roads or around other infrastructure. One way we manage this is through the use of a storm water retention tank. The amount of rainfall that is expected in the area is measured, and then, as an architect, you determine the size of the facilities that are required to handle the amount of rainfall.

The other way is to make the ground surfaces of the site completely permeable to water so that the water passes through the surface and straight into the ground.

New projects have to abide by these new regulations, and if they don't, they are not given approval to be built. To apply for a building licence, owners have to show what storm-water management practices they have in place - or prove that they will be built. Inspectors will then be sent to the site to make sure this happens.

Meanwhile, here in Viet Nam, we don't have such strict regulations and new buildings are not required to handle storm-water drainage on site. Ultimately it is the client's choice as to whether they want to invest in these storm-water management techniques or not.

I believe it is our responsibility as architects to design for the environment and not against it, and I always encourage our clients to do the same. It will take small steps like these to make big changes in the future and find solutions to problems such as flooding in major cities.

Sang: I have built a rain retention tank on my house's top floor which I think helps reduce flooding. The storm water can also be for daily use.

This is not a new idea. Before the water supply company was able to supply enough water for all households in inner districts, people used to have such rain water tanks. Even now, in the countryside, these tanks are still popular.

My tank alone cannot stop flooding in the city. However, it would make a big difference if all households had their own tanks.

Moreover, people should keep local lakes and sewerage systems clean by not littering or filling them up with construction materials. Don't just blame relevant authorities for floods because it is also our responsibility. — VNS

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