Journal of the Japan Society of Erosion Control Engineering, Vol.58,No.3,2005
Sediment disasters caused by the Mid Niigata Prefecture Earthquake
and changes of sediment movement after snow melt
Hiroshi KAWABE Yutaka GONDA Hideaki MARUI Naoki WATANABE Satoshi TSUCHIYA
Nobutomo OSANAI@Taro UCHIDA Jun'ichi KURIHARA Yoshimitsu NAKAMURA
Kimio INOUE Kiichiro OGAWA Satoshi ONODA
Abstract
Many slope failures and landslides occurred in the focal region by the mid Niigata
prefecture earthquake, 2004. Along the River Imo several landslide dams were formed
and the channel were occluded. The mid Niigata prefecture area is a very eminent
area of heavy snowfall and especially the maximum depth of snow of the basin of
the River Imo which suffered an enormous quake damage exceeds 3m. Therefore, the
enough attention against sediment movement which will occur during snow thawing
season is necessary. From the field investigation, though remarkable new slope
failures and expanded old slope failures were not found, unstable sediment which
was carried by snowmelt water from the upper part of slope is accumulating at
the foot of slope failures by the earthquake. There is a great possibility that
the unstable sediment will be moved rapidly again at the time of rainy season
or typhoon and develop into debris flows. Therefore, it is necessary to intensify
a monitoring system against sudden sediment movement and aggradation at the lower
reaches in the flood season.
Key words: the mid Niigata prefecture earthquake, sediment]related disaster, sediment
movement, snow melt
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