- pp.1-47, 2017
[Objective] Since 2011, large-scale disasters beyond assumptions of governments have occurred frequently throughout Japan, and hazard maps are in the process of change with law amendment etc. Evacuation regime is being improved on the premise of evacuation in a wider area, and the hazard maps are being renewed to assume the maximum class natural disaster. On the other hand, safe areas on the hazard maps will be decreased, consequently residents will need to determine safe places at emergency in their own judgment and evacuate. In this study, conducted the current situation survey of creation and disclosure of flood hazard maps and whether the contents are compatible with wide area evacuation, then extracted issues and proposed to solve using GIS. [Method] First of all researched the current situation of the flood hazard map. The survey target was all municipalities in Hokkaido, and we researched the creation situation, the disclosure situation, and the contents of the flood hazard maps. Also conducted a hearing survey on the current situation and issues of the hazard maps to the Hokkaido Government Office. Based on the results of the current situation survey, extracted "issues related to maintenance" such as creating and disclosing hazard maps, and "design issues" such as contents and displays described on the hazard maps. The design issues were discussed mainly based on easiness of comparison of maps for wide-area evacuation, namely, unity. Furthermore, we evaluated the current situation of the flood hazard maps of all the municipalities in Hokkaido against the extracted 'design issues.' Finally, we proposed a flood hard map that solved the issues using GIS, and summarized the creation workflow. [Result] Based on the results of the current situation survey, it was found that the actual number of municipalities creating and publishing flood hazard maps exceeded the number of grasped by the Hokkaido Government Office and the Ministry of Land, Infrastructure and Transport. Meanwhile, revealed that there are municipalities that have not created even though flood hazard maps are necessary. In addition there were some municipalities that have issues concerning disclosure situation. Also, it turned out that the design of flood hazard maps have wide variation. When evaluated the current situation on three factors, "cardinal direction", "scale of background map", and "color coding of supposed flooding depth", the dispersion of cardinal direction was particularly large. On the other hand, related to color coding of supposed flooding depth, there were also places where the risk of misreading was predicted. Furthermore, indications such as evacuation places and supposed inundation areas had been divided in administrative districts. Created a sample map around the Oasa area in Ebetsu city as an example aimed to solve these problems. This sample map was created using free GIS software, and geoprocessing data released by the government. Then organized and wrote down the work flow as a manual. With this, strived for promote the creation of flood hazard map by municipalities and others. In addition, Added location information to this map file. Thereby made it possible to check the current position when referring the map on the mobile terminal. [Discussion] Can't assert that the proposed sample map to solve the problems is a perfect form of a flood hazard map, however if the way to create hazard map at low cost that isn't limited by administrative districts will spreads, It is considered to leading to mediate between of hazard maps of municipalities. Still, although the solution proposed in this study showed part of the solution concerning the creation and disclosure of a hazard map, it has not yet solved the issue related to public dissemination of the hazard maps that were released. It is considered as a future task to encourage residents' crisis consciousness not only to prepare hazard maps.