It is important for prediction of time of landslide occurrence for mitigation of landslide disasters. Several physicallybased 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. （2006）. 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.

Target strength of sabo soil-cement is set in accordance with the necessary strength for facilities and parts. However, this does not guarantee the appearance of hydration reaction desirable for the target strength for INSEM material. INSEM method is one of the sabo soil-cement methods. In order for INSEM material to have a hydration reaction, addition of water is being practiced based on the optimum moisture content. Adding water is necessary when adding cement, because there is not enough amount of water in the amount provided with the optimum moisture content. With the fact in mind, we have conducted a study on the strength range to acquire stable strength of INSEM material. As a result, it is concluded that the minimum amount of cement and the minimum compression strength are required in order to strengthen the whole material by hydration reaction. The minimum unit of cement amount depends on each material ; however, the minimum management strength was about the same value as 2.0/mm². Aiming to produce INSEM material using stable strength quality, we need to set the target strength higher than the minimum management strength value which enables us to recognize the hardening at the point of its appearance through the hydration reaction. Our management of material with the assessed values makes it possible for us to produce the rational and reliable INSEM material.

There are two kinds of sabo dam such as open-type and close-type, and especially several kinds of dams for open-type dam have been proposed taking into account continuity of water flow and sediment runoff. Sedimentation by sabo dam such as sediment control function is usually examined using hydraulic model tests, because hydrostatic pressure distribution is always not satisfied near open parts in a storage area of the dam in case of open-type sabo dam. However, the sediment control function and the effect of sediment runoff on bed variation is not fully discussed for open-type sabo dam. In present study, hydraulic model tests are conducted for several kinds of open-type dam, and, for some examples, we will introduce the sediment control function and the temporal change of bed variation along the river channel. Additionally, hydraulic characteristics near open parts of sabo dam are shown such as vertical distributions of pressure and velocity, longitudinal of free surface and flow patterns.

On October 29, 2014 during a heavy rain event, a large landslide occurred in Kosland, Badulla District, Central Sri Lanka. The landslide and associated debris flow destroyed several local houses and killed more than 30 people. Following the landslide, an aerial reconnaissance by helicopter on November 5, 2014 and field observation between 19 th and 20 th November, 2014 were undertaken by JICA Project Team to understand the occurrence mechanism of the landslide and identify further hazard of the landslide. This report summarizes the observation results conducted by JICA Project Team, presents the geological explanation of the mechanism and causes of the landslide, and gives suggestion on emergency mitigation measures for further movement of the landslide.