Flood and evacuation simulations considering the risk of evacuation route

Toshihiro Morita

Tuesday 30 june 2015

12:51 - 12:54h at South America (level 0)

Themes: (T) Flood risk management and adaptation, (ST) Flood risk assessment, Poster pitches

Parallel session: Poster pitches: 5J. FloodRisk - Assessment

In recent years, flooding that exceeds the design capacity often occurs. In suoh situation, voluntary evacuations by the residents are recommended. However, the shortest route to the shelter is not always safe. Evacuating residents should know safe routes and shelters. In this study, water-related risks with respect to the evacuation route disasters are evaluated. Walking evacuation safety in the case of flood and inundation in Kashima City, Saga Prefecture, Japan is considered using flood and evacuation simulations. This area is surrounded by the sea and two rivers, so that it is vulnerable against water disasters. In the flood analysis, the data of the detail ground and structure's heights' are obtained by the laser profiler system to give precise water depth information on the road during flood. Precipitation data in 1976 when the water disaster occurred in Kashima City are used for the simulation. The computed results show that water depth in the northern part of the city increased, whereas flow velocities in the eastern part of city were high. This result insists that the shelter of the city was not always safe. In the evacuation simulation, the residents go through the roads that were modeled by a network model to reach to the shelter of the city. This simulation gives a required time for the residents to evacuate to the shelters and ranges of the residents' movement for the evacuation. By considering the tunnels and waterways those were not seen in the hazard map of the city, more actual selection of evacuation route becomes possible. With this analysis, many residents could not reach to the present shelters of the city. Because of many roads inundated, there are residents who can’t evacuate to the nearest shelter. Finally, locations of safe shelters are examined. They are existing sometimes on the way the residents must pass through the dangerous routes. These results show that the shelter should be put considering the topographical characteristics and the risk of the evacuation route.