Distribution and Characteristics of Frequent Inland Inundation Areas in Osaka City

Abstract

　For this study, we extracted the frequent inland inundation area in Osaka city using maps of flood damage during 1993–2012. The maps were drawn manually for each city as paper-based flood records. Because of the unfixed patterns and methods of drawing the maps, these maps have not been used for flood damage vulnerability analyses. We have translated these paper-based maps into digitized maps on GIS database, and have extracted the frequent inland inundation area. The result of analysis of the extracted area is the following: Frequent inland inundation area tends to be distributed in "plain" than "depression" areas, and sewer construction is conducted predominantly in “depression” areas. The “plain” and “depression” areas are extracted using the flood inundation model. Furthermore, results clarified that the frequent inland inundation area tends to be distributed to the area 1) with a small slope or low elevation; 2) around the structure which divides the land surface flow and sewer by such as road and rail; and 3) around the school spacing in a single line.