ABSTRACT
After World War II in Japan many polders have been reclaimed from the sea and lakes. Most of them are used as farmland, but large tracts of land were reclaimed as cheap industrial and residential areas. During the postwar high economic growth period, the population settled increasingly in these low-lying urban areas, which became the heartland of economic activities. Currently more than half the Japanese population is concentrated in low situated areas that are prone to flooding. These areas face typical lowland problems such as land subsidence, salinity and high flood risks.
