A car is submerged in water on Nguyễn Gia Thiều Street in Hà Nội's Hoàn Kiếm District after the heavy rain on Sunday. — VNS/VNA Photo

HÀ NỘI — The northern region, including capital city of Hà Nội, will continue to witness heavy rain with the possibility of tornadoes and lightning after the highest rain levels in 36 years occurred in the capital city on Sunday (May 29), according to meteorologists.

The two-hour downpour flooded several streets in Hà Nội and many vehicles were submerged.

This was a phenomenon of intense thunderstorms that surpassed the record set in 1986, said Trần Hồng Thái, director of the General Department Hydrometeorology under the Ministry of Natural Resources and Environment.

The cause of the heavy rain was the influence of the compressed low trough which made the temperature in the northern and central regions of Việt Nam increase, Thái said.

Thunderstorms first appeared in provinces of Sơn La and Hòa Bình, and localities southern of the Hồng (Red) River Delta region, then moved to Hà Nội, causing rain with great intensity lasting for about two hours, he said.

According to recorded data, the rainfall measured at Láng station in Hà Nội from 2pm to 4pm was 138mm.

Historically, cumulative rainfall in one hour on July 15, 1999, reached 114.9mm, and in two hours on June 18, 1986 was 132.5mm.

According to the data of Hà Nội Sewerage and Drainage Company, the highest rainfall on Sunday was 182.5mm measured in Cầu Giấy District while the rainfall in Tây Hồ and Hoàng Mai districts was 160.5mm and 139.6mm, respectively.

Sunday's storm was a new record in Hà Nội, Thái said.

According to meteorologists, thunderstorms often appear in the evening after a hot day in summer and are formed by very strong convection in the atmosphere.

The thunderstorms appear for a short time but are often accompanied by extreme weather phenomena such as strong winds, very heavy rain, and even hail, and tornadoes.

These phenomena are very dangerous, especially for people who are on the street during this time.

In Việt Nam, thunderstorms often happen from April to October every year.

With this year’s weather developments, the meteorological agency predicted that in the future, the North will see more rain than the average for many years.

There is a very high risk of flash floods and landslides in mountainous provinces and inundation in low-lying areas.

From now to Tuesday (May 31), due to the influence of the low-pressure trough which is compressed through the northern region, there will be moderate and heavy rain in the northern mountainous and midland areas, and very heavy rain in some places with rainfall level from 80 to 120mm, and over 150mm in some areas.

There will also be showers and thunderstorms in some provinces of the Hồng River Delta region.

The capital is forecast to have showers and thunderstorms at times, with heavy rain locally, with the possibility of tornadoes, lightning, hail, and strong winds.

Inundated Đào Tấn - Liễu Giai - Nguyễn Chí Thanh intersection, Hà Nội. — VNA/VNS Photo

Drainage issues

According to architectural and planning experts, the main cause of flooding in Hà Nội after heavy rains was that the drainage system had not met the requirements while many ponds and lakes were filled and there is no system of reservoirs so the water drainage capacity is very weak.

Hundreds of urban projects have been built and put into operation, but there is a lack of technical infrastructure in new urban areas, leading to situations such as traffic jams and flooding.

Architect Trần Ngọc Chính, chairman of the Việt Nam Urban Planning and Development Association, said: “To solve the above problem, along with reviewing and improving the quality of the water supply and drainage system, the city needs stronger and more synchronous policies and mechanism such as permitting private investors to participate in the construction of infrastructure works in exchange for certain benefits.

"In addition, the Hà Nội authorities also need to arrange appropriate and necessary spaces for the construction of reservoirs as well as strengthen the capacity of the main pumping stations, and use simulation software on the hydrological system of the city to monitor water level data in sluices and reservoirs so as to proactively prevent and control flooding when raining."

In the short-term, to cope with the unusual weather developments this year, the Hà Nội Sewerage and Drainage Company maintained and repaired the pumping stations to proactively ensure the prevention and control of flooding in case of heavy rains.

Information on rainfall, pump station operation mode, and inundation situation will always be updated in real-time on the Drainage Monitoring Centre's software. — VNS