Heavy rainfall is expected in HCM City until September 30, with the rainy season extending into early November, according to the Southern Regional Hydro Meteorological Centre in the city. — Photo echip.vn

HCM CITY — Heavy rainfall is expected in HCM City until September 30, with the rainy season extending into early November, according to the Southern Regional Hydro Meteorological Centre in the city.

Lê Văn Khoa, deputy head of the city’s People’s Committee, said the city would send SMS phone messages to the public about possible flooding caused by heavy rains.

The Centre for Urban Flood Control Programme said that a map of flood-prone areas would also be completed. The map is part of a project on flood risk management being implemented with a loan from the World Bank.

If approved, the map will be completed before the rainy season next year.

An extraordinary amount of rainfall, a clogged drainage system, and on-going construction projects all contributed to causing the historic flooding in HCM City on Monday (September 26), the heaviest in 40 years.

According to the city’s Centre for Urban Flood Control Programme, the city’s drainage system could not accommodate the amount of rainfall within a short time, causing flooding throughout all  the city’s districts.  

Prime Ministerial Decision 752, which gave approval to HCM City’s Drainage System Master Plan to 2020, had called for a designed capacity of 95 mm of rainfall within three hours for the city.

However, the decision is now out of date because rainfall of over 100mm occurs more frequently and flood tides have increased from 1.5 metres in 2006 to 1.68 metres.

The torrential rain on Monday was measured at 179 mm in District 1 and over 100 mm in other districts.

Uncontrolled waste and canals encroached on by illegal housing are two other factors that have worsened flooding.

In addition, residents continue to drop all kinds of waste in canals and at gates of drainage systems. When heavy rains begin to fall, the water pressure causes waste to clog drains.

“Before the rain, we collected waste and arranged staff at places prone to flooding,” a representative of the Centre for Urban Flood Control Programme said.

The city has issued many decisions to impose stiff fines on those who drop waste without permission, but few residents have actually been fined.

Though encroachment on canals and water drainage systems is common, local authorities have not been able to solve the problem, with many projects progressing slowly.

During a recent check of the drainage system and canals near Tân Sơn Nhất Airport, the city’s People’s Committee chairman Nguyễn Thành Phong noticed that houses had been built illegally on the canal. On the bed of canal, waste and construction materials clogged the water flow.

The slow progress of flood prevention projects is another reason behind continued flooding incidents.

Many flood-prevention projects during the 2016 – 2020 period have been behind schedule due to administrative procedures.

For example, the VNĐ5.1 trillion (US$230 million) project to improve the Xuyên Tâm canal to reduce floods on an area of 700 hectares in Bình Thạnh and Gò Vấp districts was handed over to a private company in 2015, but the bidder had yet to do anything

“Projects supporting water drainage under the impact of climate change have not been implemented,” a representative of the Centre for Urban Flood Control Programme said.

Though many of the projects were approved by the Prime Minister as far back as eight years ago, they have yet to be completed.

Only one (Nhiêu Lộc - Thị Nghè) of 10 drains to control flood tides and 40 per cent of dykes (60 km in total of 149km) have been built. The delay has been caused by a lack of money.

Total capital for such a project would cost several hundred trillion (several billion US dollars) but the city has only $1.1 billion for it.

Several water drainage projects now under construction are believed to be affecting the entire drainage system.

The two-hour torrential rain caused serious flooding on 59 streets in HCM City, causing traffic chaos, flooding houses and delaying 12 flights at Tân Sơn Nhất airport that had to be diverted to other airports.

According to initial statistics of insurance companies, more than VNĐ4 billion-10 billion ( $180,000 - 450,000) was spent for compensation on automobiles that broke down due to heavy rains in the last two days. — VNS