Journal of the Japan Society of Erosion Control Engineering, Vol.57,No.6,2005

Sediment‐related disaster caused by typhoon Tokage(T0423) in Tamano city, Okayama pref. and around Sanuki city, Kagawa pref.(prompt report)

Kazuki MATSUMURA, Masahiro KAIBORI, Kunio MIZUHARA, Akira SUEMINE, Nobuhiro EBISU, Tomoyuki NORO, Takao YAMAKOSHI

Abstract

Many sediment disasters have been caused around the west parts of Japan by Typhoon No.23 (Tokage). This paper mentioned about two districts where caused severe sediment disasters. One of the sediment disasters caused five casualties in Tamano City, Okayama Pref. and the other disaster caused three casualties in Sanuki City, Kagawa Pref. on 20th October 2004. The cause of rise such casualties was regarded that these torrents were not anticipated as debris flow torrents. The volume of sediment discharge was rather small, comparing the heavy rain fall, and that is to say, the scouring river bed was intensified, when sediment supply to river channel was little, and it became a cause of collapses of bank protection works. And another thing, it was recognized that the slope failures in the Monnyu river catchments occurred mainly in about 15 years old artificial forest.

Key words:debris flow, collapse, sediment disaster

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