Author(s): Thanh Tu Vu; Tawatchai Tingsanchali
Linked Author(s):
Keywords: Flooding depth; Inundation map; Flooding damage assessment; Hazard; Risk
Abstract: Hoang Long is the largest river in Ninh Binh province, Vietnam. This province is frequently affected by flooding due to heavy rainfalls in the river basin. Rainfall frequency analysis was done to obtain a maximum 7-day rainfall for various return periods, and to construct design hyetographs corresponding to 5,10,20,50,100 and 200-year return periods. Design flood hydrographs corresponding to different return periods, recommended by international standards as the European Flood Directive (EC, 2007), were obtained by using MIKE-NAM. These results are input to MIKE 11 hydrodynamic model to simulate flood flow in Hoang Long basin. The NAM and MIKE 11 models were calibrated and verified using past flood data. Using the maximum water levels computed by MIKE 11 model at different locations along the rivers and floodplains and digital elevation map (DEM), flood inundation maps were developed for Ninh Binh province. Flooding depth and inundation area corresponding to various return periods were determined. From the inundation maps and field survey data, including interviews, damage curves for residential, agricultural and roads damages were estimated. Flood hazard and flood risk maps were constructed typically for the 20-year and 50-year return period floods. For flood hazard and risk assessment, the combined effects of flood depth and flood duration were considered for each community in Nho Quan and Gia Vien district. These maps are useful for flood risk zoning and flood mitigation planning in order to increase the flood risk awareness, preparedness and resilience in the Ninh Binh province, as recommended by national and international Agencies as UN-ISDR (2007).
Year: 2012