On the afternoon of 29th May, 2022, few hours of heavy rain caused serious flooding in Hanoi, affecting the lives of thousands of people in the city. The National Center for Hydro-Meteorological Forecasting said that with a rainfall of 140 mm, Lang station recorded a record of cumulative daily rainfall over the past 36 years. The last time the area recorded 132 mm of rain within 2 hours was on June 18, 1986.
According to Trinh Ngoc Son, Deputy Director of Hanoi Sewerage Company Limited, the rain exceeds the design capacity of the urban drainage system.
By design, the system can meet the drainage capacity with 310 mm of rain in 2 days. Meanwhile, many rain spots in Hanoi recently reached 180 mm in just 2 hours. The heavy rains that fell in a short time exceeded the design capacity of the city's drainage system.
Mr. Son said the unit recorded 35 points of flooding in the city after the rain yesterday afternoon, in which many concentrated in the To Lich river basin in the districts of Hai Ba Trung, Hoan Kiem, Thanh Xuan and Cau Giay. and some areas in Nhue river basin (Nam Tu Liem district), Long Bien basin.
According to statistics, the inner city's drainage system includes 5,700 km of culverts, 254 km of ditches, rivers and canals, 125 regulating lakes, 10 main rainwater pumping stations and 5 factories and wastewater treatment stations.
This system is divided into 5 areas including: To Lich, Ta Nhue, Huu Nhue, Ha Dong and Long Bien. Of these, only the To Lich river area has been fully invested.
Some main drainage pumping stations such as Lien Mac and Yen Nghia have been completed but have not been effective due to the unsynchronized system of channels and discharge channels. The Gia Thuong and Cu Khoi pumping stations have not been renovated and dredged, affecting water drainage in the system.
Source: the Internet