Characteristics of the Flood Damage caused by the Kanogawa Typhoon in the western Suburbs of Tokyo

Abstract

Owing to the Kanogawa Typhoon, more than 460, 000 houses were damaged by the flood in Tokyo. This is a record-breaking damage by the flood in Tokyo. The flooded district by the Kanogawa Typhoon in Tokyo may be divided into two main classes from the topographical point of view, namely A) the delta region in the eastern and the south-eastern parts of Tokyo, and B) the western suburbs of Tokyo on the Musashino upland (in the south of the Kanto plain). The vast flood in the delta region had been caused by the broken banks of the Arakawa, the Tama, the Edo, etc. In case of the Kanogawa Typhoon, however, the water gathered into the great part of the delta region and remained for a long time without no broken banks. Few parts of the districts along the small streams and the hollow places in the western suburbs of Tokyo on the Musashino upland had been flooded. However, the great part of the western suburbs on the plateau was flooded by the Kanogawa Typhoon. This fact is one of characteristics of the flood damage in the western suburbs of Tokyo in case of the Kanogawa Typhoon. Because the heavy rain was centred around the Musashino upland by the Kanogawa Typhoon, and many hollow places and the small river basins on the plateau were flooded. The flooded districts caused by the Kanogawa Typhoon in the western suburbs of Tokyo on the Musashino plateau were the districts along the small streams, which have headsprings on the plateau and many hollow places. The great part of the damaged houses in the western suburbs of Tokyo were mostly newly built ones, by the streams or on the hollow places after World War II. As there has been a sudden rise in prices of the land in the western suburbs of Tokyo, many houses have been built in low-price lands. This fact is the other characteristic of the flood damege in the western suburbs of Tokyo. In conclusion, it may be said as follow: 1) The flood damage caused by the Kanogawa Typhoon is “the flood damage on the upland” in the western suburbs of Tokyo, 2) the natural causes of the flood damage increased because of the rapid expansion of residential districts in the western suburbs of Tokyo. Note: The shaded portions of Fig. 1 and 3 show damaged districts.