Journal of the Japan Society of Erosion Control Engineering, Vol.58,No.4,2005
Outbursts and disasters of Takaisoyama and Hose Landslide dams (1892) in
East Shikoku
Kimio INOUE Toshio MORI Tatsuhei ITOU Yoshihisa KABEYAMA
Abstract
Takaisoyama and Hose landslides occurred by heavy rainfall of typhoon in 25 July,
1892, in east Shikoku. These landslides blocked rivers and formed landslide dams.
Many old documents illustrated outbursts and disasters of Takaisoyama and Hose
Landslide dams. Takaisoyama landslide blocked Naka River and formed landslide
dam of 71 m in height and 7.25~107 m3 in volume (Terado, 1970). The landslide
dam broke down when the dam lake was filled with water after 1.87~105 seconds
( 52 hours), and the big flood rushed down the valley of Naka River, with the
damage of more than 300 houses and the victims of 60 persons. Calculating by Manning
formula, the peak flood discharge started by velocity of 10`12 m /second(average
velocity of 5 m /second)and a volume of 3.0~104 m3/second, and rushed down by
3 hours at the distance of 49.3 km from the landslide dam. This flood reached
by 7.5 hours at the distance of 72 km in the estuary of Naka River. Hose Landslide
blocked Kaifu River and formed landslide dam of 80 m in height and 3.3~107 m3
in volume. The landslide dam broke down after 1.08 ~ 105 seconds (30 hours) or
1.94 ~105 seconds (54 hours ), and the big flood rushed down the valley of Kaifu
River with the damage of more than 20 houses and the victims of 47 persons. This
flood rushed down in 3]4 hours at the distance of 23 km in the estuary of Kaifu
River.
Key words:landslide dam, outburst, flooding, Takaisoyama, Naka River, Hose, Kaifu
River
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