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Sediment disasters have occurred with higher frequencies in recent years because of local heavy rains caused by line-shaped precipitation systems and torrential rains accompanying large typhoons. Since rescue operators are constantly under physical risk at disaster sites, there is a need for technologies to predict the occurrence of secondary disasters. The authors research the measurement of slope displacements by focusing on a depth camera that is readily deployable, can be easily set up, and enables monitoring of an extensive area but does not require expert knowledge to carry out measurements. In this process, we confirmed the difficulty of measuring slope changes preceding failure when the depth camera (DC) is set at a distance because of the large measurement errors caused by the limited depth resolution and poor measurement conditions under rainfall. In this study, we propose a new method for analyzing depth image data obtained by a depth camera and verify its validity for displacement measurements. After comparing the previous and proposed methods, we could confirm that the latter enables one to detect slope changes from minute deformations. When compared with the results of extensometers that directly measured the slope, we found that the results displayed similar tendencies of increase. Therefore, by measuring displacements preceding a slope failure using a depth camera and analyzing the depth image data acquired using the proposed method, we found that it is possible to detect minute changes that precede slope failures. [ABSTRACT FROM AUTHOR]

This paper intends to clarify the relationship among the important attributes of flood prevention measures and the effects of socio-economic factors on the public preferences of selecting the measures based on the choice experiment approach. The experiment was conducted via a mail survey in the Toki–Shonai River basin of central Japan. First, the relationships among the five attributes (external flood reduction, internal flood reduction, early warning systems, environmental protection and willingness to pay for such countermeasures) were quantitatively clarified, and it was shown that an early warning system in terms of fatality rate due to floods was lowly evaluated by the public. Second, certain socio-economic factors, like annual household income, flood experience, sex and distance to a river, had statistically significant impacts on the utility functions in our model. Third and finally, there was a statistically significant difference in regional model results between Toki city and Kita ward of Nagoya city. These results imply the necessity to implement localized watershed management in Japanese urban catchments, and to improve information provision and public understanding of flood risk. [ABSTRACT FROM AUTHOR]

The focuses on the authors' opinion about a study that presents a summary of the main statistical characteristics of fatalities and casualties due to floods in Japan since 1947. According to the authors, early warning and evacuation is the best method for reducing the loss of life from floods and other natural disasters.

In conventional flood damage reduction studies, flood damage is usually estimated with a damage function according to the depth of inundation. However, this method may not reflect the conditions of each family residing in the floodplain because it ignores not only the distribution of flood damage but also the effect of building characteristics and residents' preparedness. This paper uses data from a questionnaire based survey (N = 3,036) conducted 17 months after the Tokai Flood of 2000 that caused disastrous losses to household properties. It provides a conceptual "doughnut structure" model of flood damage to houses and house contents and a mathematical basis for models to explore the determinants of flood damage. Besides the inundation depth, house type significantly affects both the house structural and content damage probabilities, while house ownership and house structure affect house damage probability but not house content damage probability at a given depth. Inundation depth, residing period, and household income significantly affect both house and content damage values. In addition, house ownership has a significant impact on the house damage value, while house structure has an impact on content damage value. [ABSTRACT FROM AUTHOR]

This study examines how fiood risk perception and home ownership atTect residents' preparedness for floods, foeusing speeifically on the ease of the Tokai flood disaster in Nagoya City, one of Japan's biggest metropolises, in 2000. The greatest rainfall ever recorded in Nagoya City (566.5 mm) occurred on 11-12 September 2000; as a result, a local river hurst its banks and flooded the city. A survey was conducted of residents of the affected area in Nagoya City and its adjacent region. The respondents were asked to rate the extent of their experience with, anticipation of, and preparedness for floods hefore and after the lokai disaster in terms of taking special measures against Hoods. The results showed that the degree of preparedness for floods was determined hy the level of fear of floods and the amount of damage sustained during the Tokai flood, especially for homeowners. However, the residents' preparedness did not depend on their anticipation of floods. These findings show that preparedness for tloods depends on ownership of a home, fear of flooding, and the amount of damage from previous floods rather than on previous experience with and antieipation of floods. [ABSTRACT FROM AUTHOR]

This paper aims to evaluate the comprehensive efficiency of flood disaster prevention investment from 1955 to 1999 by developing and applying an integrated evaluation model. Our analysis results have clarified some important issues currently being discussed in Japan. Firstly, the average values of normalized flood losses decreased greatly between the 1955-1961 period and the 1984-1999 period. Secondly, the ratio of human loss to total loss caused by floods in Japan may be less than 10%, based on the concept of the value of statistical life (VOSL) and values estimated from the risk-money tradeoff. The proportion of intangible effect to total loss increased from less than 10% before the 1970s to approximately 20% after that period. Finally, flood prevention investment in Japan effectively reduced losses caused by flooding before the 1960s; however, since the 1980s, investment has changed from an efficient mode to an inefficient mode, not only from the economic standpoint, but also from that of total flood loss saving. [ABSTRACT FROM AUTHOR]