2004 年三重県宮川村および徳島県木沢村の斜面崩壊プロセス

Abstract

2004 年は多くの台風が日本に上陸し，各地に甚大な土砂災害を引き起こした。ここでは，その中から台風10 号による徳島県木沢村および台風21 号による三重県宮川村（現大台町）での斜面崩壊等の土砂移動現象に着目して，それらの発生メカニズム，土砂移動現象の特性などについての調査結果と解析結果について述べる。とくに，現地で観測された段階的崩壊プロセス，地下の集水構造と土砂移動の関係，崩壊過程の違いによる天然ダムの規模の違いについて焦点を当てて報告する。

In 2004 a lot of typhoons attacked the Japanese Islands and they caused a lot of sediment related disasters. Among them, we have investigated the sediment disasters in Miyagawa Village by Typhoon 21 and in Kisawa Village by Typhoon 10 and collected the information on the process of some slope failures and the characteristics of bedrock feature. In this paper, we analyzed the water movement in the slopes and its role on the slope failure, the phased failure process observed in Kotaki, the influence of the phased failure on the formation of landslide dam. As a result, a numerical simulation could explain the phased slope failure in Kotaki, and a hybrid-debris flow model could show such a slope failure process produce the difference of height, width and length of landslide dam.