Assessment of floodwater behavior in Van Coc Lake, Hanoi in event of emergency situation
2019
Anh, S.H. ((Kyushu University, Fukuoka, Fukuoka (Japan). Graduate School of Bioresources and Bioenvironmental Sciences, Department of Agro-environmental Sciences), (Institute of Water Resources Planning, Hanoi (Vietnam). Division for Water Resources Planning for the North Region)) | Tabata, T. | Hiramatsu, K. | Harada, M. | Son, L.V.
Van Coc Lake located in the Dan Phuong and Phuc Tho, Hanoi, Vietnam, has an area of 30.83 square Km. It is usually dry and includes arable land and residential areas. However, to protect Hanoi City from catastrophic floods, in emergency situations, it receives the floodwater from the Red River as a regulating reservoir and drains the floodwater to the downstream Day River through the Day Weir. We performed numerical simulations to assess the movement of floodwater in this lake and evaluated the impact of floodwater on its residential areas. A two-dimensional depth-integrated hydrodynamic model was constructed to simulate inundation in this lake. The model was validated and the effects of Manning's coefficient of roughness were examined. In case of emergency, it has to receive an inflow of 2,500 cubic m/s into the area. Inflow rates of 1,200 and 600 cubic m/s were also examined to compare the results. The simulation results indicate that this lake was entirely inundated in 13, 28, and 56 h by inflow rates of 2,500, 1,200, and 600 cubic m/s, respectively. Between 66% and 99% of residential areas were inundated. The areas with highest velocity were primarily focused behind the gate with a velocity of 1.5-1.8 m/s.
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