We have attempted to identify parameters of a tank model for the Saba River basin, where the great sediment disaster occurred in July 2009, with observation data in order to present a highly accurate method providing a critical line for sediment-related disasters (CL). The identification of the model parameters can be done with high accuracy using the shuffled complex evolution method which is one of the global optimization methods and the proposed model is more reproducible than the Japan Meteorological Agency (JMA) model. We set up a CL by using soil water index calculated by this model and found that the accuracy of CL evaluated by our model is higher than that evaluated by JMA's model. It is found that the construction of an appropriate tank model based on the observation data is very important for improving the accuracy of sediment-related disaster predictions.

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 We propose a seismic risk evaluation method of linear facility for risk finance. This method treats linear facility as discretized interval, a number of structure's vulnerability as aggregate damage function. It may have applicability to production of previous study. In addition, we estimate seismic risk of railroad which is 20km straight line made by typical four structures in the metropolitan area, and describe risk in various forms.

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 Labour accidents in disaster-relief and disaster restoration work following the Niigata Chuetsu Earthquake (2004) and the Niigata Chuetsu-oki Earthquake (2007) were analysed and characterised in order to raise awareness of the risks and hazards in such work. The Niigata Chuetsu-oki Earthquake affected houses and buildings rather than roads and railways, which are generally disrupted due to landslides or slope failures caused by earthquakes. In this scenario, the predominant type of accident is a "fall to lower level," which increases mainly due to the fact that labourers are working to repair houses and buildings. On the other hand, landslides and slope failures were much more prevalent in the Niigata Chuetsu Earthquake, resulting in more accidents occurring in geotechnical works rather than in construction works. Therefore, care should be taken in preventing "fall to lower level" accidents associated with repair work on the roofs of low-rise houses, "cut or abrasion" accidents due to the demolition of damaged houses and "caught in or compressed by equipment" accidents in road works and water and sewage works.

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 It is difficult to deregulate sediment-related disaster warning information, for the reason that it is difficult to quantify the risk of disaster after the heavy rain. If we can quantify the risk according to the rain situation, it will be an indication of deregulation. In this study, using logistic regression analysis, we quantified the risk according to the rain situation as the probability of disaster occurrence. And we analyzed the setup of resolutive criterion for sediment-related disaster warning information. As a result, we can improve convenience of the evaluation method of probability of disaster occurrence, which is useful to provide information of imminently situation.

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