Prediction of time and location of landslide occurrence by using simple hillslope hydrology model

Reiko AKIYAMA, Atsuhiko KINOSHITA, Taro UCHIDA, Teruyoshi TAKAHARA and Tadanori ISHIZUKA

It is important for prediction of time of landslide occurrence for mitigation of landslide disasters. Several physically�]based models have been proposed for assessing spatial pattern of landslide susceptibility. However, still it is difficult to predict both time and location of landslide occurrence using physically�]based model. In this paper, we proposed a method for prediction of time and location landslide occurrence. We estimated critical condition which consisted rainfall intensity and duration time. We modified simple steady�]state slope stability model “H�]SLIDER" by using hillslope hydrology model proposed by Rosso et al.�i2006�j. Hillslope hydrology is modeled by coupling the conservation of mass of soil water with the Darcy's law used to describe seepage flow. We applied this model for the case of rainfall event in Hofu city in 21 July 2009. Here we found that once we can set suitable value for cohesion of soil, our model can reproduce both time and location on shallow landslide in Hofu city. In result of sensitive analysis of soil thickness and soil mechanical and hydraulic parameters, it is clarified that condition of soil thickness is thicker or soil cohesion is weaker generated missing ratio increasing.