Flood prevention solution for Nai bridge area (Vinh city)
(Baonghean.vn) - The Nai bridge area, ditch No. 2 (Vinh City) is often flooded. The depth of flooding during storm No. 5 on September 18 was about 60cm. The water receded 1.5 hours after the rain stopped. This is one of the most worrying areas when there is heavy rain and needs to be promptly solved to prevent flooding.
The upstream area of Nai bridge, Nguyen Tai street, block 2, Truong Thi ward; Nguyen Van Cu street (from Ho Tung Mau street to Le Hong Phong street) is often deeply flooded when there is prolonged heavy rain. This is also the walking street area of Vinh city, if flooded, it will greatly affect the urban beauty and the quality of life of the people.
It is known that the drainage direction here is to flow into ditch number 2, through Nai bridge, into the Central Park regulating lake, to the Vinh Tan ecological urban area regulating lake and then toBlack Bridge Pumping Station, forced pumping into Vinh River.
 |
| The upstream area of Nai bridge is often deeply flooded when heavy rain lasts for a long time. Graphics: Lam Tung |
The drainage basin is Hung Binh ward, part of Truong Thi ward flows into it. The cross-section of ditch No. 2 has the following sections: Upstream of Nai bridge BxH (concrete canal opening) = 6 x 2.15m = 12.9 m2, the section after Nai bridge has a mud wall built by the CompanyTrung Longbuilt to reduce the clear area to 8 x 1.2 = 9.6 m2, the mud wall is 1m higher than the wastewater separation wall, reducing the ability to drain downstream. After Thong bridge, BxH = 4.8 x 1.8m.
Along ditch No. 2, anti-flooding pits have been arranged on the ditch cover (30m/pit). Along Nguyen Tai and Nguyen Van Cu streets, surface water pits have been arranged (30m/pit). The ditch system has been dredged.
| Overview of 3 floods on Nguyen Tai Street, Block 1, Truong Thi Ward (Vinh City) in 3 years (2017 - 2019). Documentary clip |
The cause of the flooding was stated by Mr. Nguyen Viet Duc - Head of Urban Management Department, Vinh City People's Committee: The downstream of Nai bridge has a mud wall (built by Trung Long Company 1m higher than the wastewater separation wall) which reduces the drainage capacity. The second ditch is basically covered with concrete panels, which reduces the drainage function. The second cause is that garbage and leaves (fallen due to storms) block the mouths of the collection pits so the water cannot drain, the city's functional forces have gone out to collect and collect a large amount of garbage here.
 |
| Image of people in Block 2, Truong Thi Ward (Vinh City) cleaning up trash on the night of October 16, 2019. Photo: Contributor |
The downstream ditch section of Thong bridge, along Nguyen Son street, has a smaller cross-section than the upstream section of Nai bridge (about 4.0 m).2The box culverts in the water supply system from the Vinh Tan Ecological Urban Area's regulating lake to the Cau Den pumping station's water tank do not have enough drainage capacity, leading to insufficient water supply to the pumping station and causing flooding in the areas of Nguyen Tai Street, Nguyen Van Cu Street... and the wards of Truong Thi, Hung Binh, Vinh Tan, and Le Mao.
Surface water collection pits along ditch No. 2 have not met water collection requirements in the current situation of climate change and urbanization.
 |
| Nai Bridge area flooded during the rain in October 2019. Photo: Archive |
The proposed solution, according to Mr. Tran Ngoc Tu - Chairman of Vinh City People's Committee, is to invest in building a new section of ditch B = 1.0m along the existing residential road connecting the ditch on Nguyen Van Cu Street and ditch No. 2.
Request Trung Long Company to demolish the mud wall downstream of the bridge because the mud wall (built by Trung Long Company 1m higher than the wastewater separation wall) reduces drainage capacity.
 Nguyen Tai Street (Vinh City) is often flooded during prolonged heavy rains. Photo: PV |
The deep and long-lasting flooding in the Nai bridge area has been happening continuously for 3 years now (the flood on October 10, 2017, December 8, 2018 and the peak flood on October 16, 2019) leading to the misery of the people, including subjective causes. Therefore, it needs to be thoroughly handled, which is an urgent request of the people living in this area./.