Examination on the Numerical Analysis Method of Large Scale Inundation due to River Flood in Urban Area

The flood disaster occurred at the Shounai River basin due to the heavy rain of typhoon 15, 2011. At Shidami area in Nagoya city, the inundation due to overflow from the river dike occurred and evacuation information was issued to 1,000,000 residents of Nagoya city. Though large scale inundation did not occur at that time, serious hazard may occur in the case of dike break. A lot of underground space exists in the Nagoya city. The underground space has the brittleness of water disaster. In this study, we treated the inundation water behavior due to dike break conditions by using of numerical analysis. Especially, the analysis model for water behavior of underground shopping center and subway line was developed for Nagoya city, the analysis model was applied to examination on inundation of Osaka city. From analysis results, the feature of inundation water behavior of Nagoya city and Osaka city are shown clearly. Moreover, it is shown that Osaka city area has the risk that the inundation spreads at far place by water flowing through subway lines in the case of dike break