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Urban flooding unavoidable

(16:31:38 PM 03/11/2014)
(Tinmoitruong.vn) - Urban flooding in HCMC is approaching the irrecoverable threshold and is seen unavoidable in the next several years, according to facts and figures at a meeting convened by the HCMC government this week.

Urban flooding unavoidable
A woman wades through a heavily flooded street in HCMC after a recent heavy rain. Urban flooding in HCMC is seen unavoidable in the next several years

Efforts now can only lessen the impacts, instead of warding off the man-made calamity.

Officials at the meeting presided over by HCMC vice chairman Nguyen Huu Tin pointed the accusing finger at acts of God, saying torrential rains have overwhelmed the city’s drainage capacity.

Heavy rains the culprit

Nguyen Hoang Anh Dung, deputy director of the city’s Flood Control Center, said downpours overwhelmed the city’s drainage system.

As many as 14 areas in the city are prone to flooding again after being upgraded to fight flooding, Dung said. Nine out of these 14 are in Binh Thanh District, which are submerged upon downpours with rainfall of over 85mm, which is the level used for designing the city’s drainage system.

“Even certain streets installed with new sewers such as Bui Huu Nghia and Phan Dinh Phung are still flooded when heavy rains occur; anti-flooding measures taken previously are not effective,” Dung told the meeting.

Le Hoang Minh, deputy director of the Department of Transport, noted that between the early 2012 and end-2013, the city had deployed projects to fight flooding at 47 sites in inner-city areas covering a total of 100 square kilometers, but 14 sites have been submerged again this year.

At this point, Vice Chairman Tin turned frustrated, criticizing local agencies for failing to tackle flooding.

“The whole world has learned of flooding in the city. Now is not the time for pointing the finger at heavy rains, or at flood tides. The key is the incompetence on the part of agencies, which cause flooding to aggravate. There is no point of blaming heaven and earth,” Tin stressed.

Poor vision

According to the Flood Control Center, the city’s water drainage facilities were designed in accordance with a master plan approved by the central Government in 2001, which has become outdated due to fast-changing weather patterns.

Under Decision 752/2001/QD-TTg issued by the Prime Minister, all sewers were designed to cope with rainfalls of between 75mm and 85mm only. However, since 2006, there have been as many as 36 downpours with rainfalls higher than 85mm, according to the Flood Control Center.

According to the anti-flooding master plan 752 incorporated in Decision 752 just mentioned, third- and fourth-tier sewers could spill over once every two years, while the third-tier sewers every three years. But the frequency now is every two weeks in certain areas during the flood tide season.

Even worse, most of such sewers were constructed at a height of 1.31 meters above sea level, by referring to the maximum flood tide at the time. Now, the record flood tide has hit 1.70 meters this month, meaning the sewers do not work at high tides.

Vice Chairman Tin looked quite annoyed at the information, saying, “It is very dangerous if the sewerage does not work now, because it is impossible to replace hundreds of kilometers of such sewers citywide.”

The vice chairman ordered the city’s Department of Transport to quickly map out anti-flooding measures and make a report to the municipal government in the next ten days.

The city government will consider projects to construct four water-regulation reservoirs, one in Thu Thiem in District 2, one in District 4, one in Binh Chanh and the final one in Thu Duc.

However, such reservoirs will be constructed first in Thu Thiem and District 4 to mitigate flooding in inner-city areas, Tin said.   

Source: SGT/VNN