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Consideration of Subsurface Water and Slope Failure in Mountain Forest Basin Using a Distributed Runoff Model

Author(s): Hasegawa Ryo; Tamura Takao; Muto Yasunori

Linked Author(s): Yasunori Muto

Keywords: Slope failure; Distributed runoff model; Amount of subsurface water storage

Abstract: Typhoon lands on Japan every year, and causes heavy rain. The rain infiltrates and becomes subsurface water. Increasing amount of subsurface water triggers an occurrence of slope failure in mountain forest basin. In Kii Peninsula, Typhoon No. 12 in 2011 caused the heavy rain that exceeded2,000mm, and generated deep-seated slope failure. Therefore, it is necessary to focus on amount of subsurface water storage in mountain forest basin in heavy rain event, and discuss the relation between amount of subsurface water and slope failure. In this study, the Tondagawa’s amount of subsurface water storage was estimated by using distributed model which include tank model. And it was considered slope failure in heavy rain of Typhoon No. 12,2011. Concretely, the amount of subsurface water storage which triggered deep-seated slope failure was discussed about time variation, horizontal, and vertical distribution. The Tondagawa upstream basin was divided into sub-basins. And the runoff analysis on Typhoon No. 12 was done. As a result, it was shown that slope failure was affected by amount of groundwater storage which is part of subsurface water. To be concrete, the risk of occurrence of deep-seated slope failure increases when the percentage of underground water was more than 40 percent of amount of subsurface water storage.


Year: 2016

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