人口と産業が集積する大都市部の水災害対策の可能性と限界

抄録

In Japan, 50％ of the population lives and 75％ of the asset is concentrated in the floodplain which occupies ca. 10％ of the land area. Flood hazard maps have been created in this “Flood Risk Area”, and it is obligatory to explain the risk to the customers when conducting real estate transactions. However, the population and economy are so concentrated that migration policies are not realistic and this lowland must be reborn as a safe city.　The first measure is the revision of the law, which requires that the building foundation height be elevated to the calculated inundation depth when rebuilding in this area. As a long-term vision, it is important to have a policy of “town development on a hill” that fills the entire town high.