We developed a victim data base (“1999-2017”) for heavy rainfall disaster events in Japan from 1999 to 2017, and 1011 victims were classified. The purpose of this study is to analyze the characteristics of victims caused by heavy rainfall disaster in western Japan in July, 2018 (“HRD2018”) in comparison with “1999-2017”. Through this heavy rainfall event, 231 people were killed or missing in western Japan. Characteristics of victims by “HDR2018” were as follows: 1) The number of victims is the largest since heavy rainfall disaster in July 1982. 2) 54% of the victims were death by sediment disaster, 35% of the victims were death by flood disaster. 3) 61% of victims died indoors. 4) 12% of the victims died after taking evacuation action. 5) 92% of the victims due to sediment disaster died near the sediment disaster hazard area. The ratios of 3) is higher than “1999-2017”. Especially in Okayama prefecture, many victims died indoors of inundated houses. It was suggested that deep inundation of 3 m or more could cause many victims. The ratio of 4) is consistent with “1999-2017”. It was suggested again that the method and timing of evacuation are important. The ratio of 5) is consistent with “1999-2017”. Understanding for hazard map information is important for the disaster prevention.

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In Hiroshima city, debris flow occurred at 166 places due to the heavy rainfall on 20 August 2014 and the death toll reached 74. We carried out questionnaires to the fire fighters belonging to Hiroshima City who worked against the sediment disaster, in order to study the needs about disaster mitigation technologies. The answers to the questionnaires were analyzed by KHcoder, a text mining methods. As a result, it was found that five kinds of disaster mitigation technologies were required by fire fighters, namely, Intelligence sharing of damage situations, Understanding situations with a birds eye view at rainy and night, Airing of evacuation instruction and information service to local residents, Understanding dangerous situations using alarm to active fire fighter, Demanding weather information and acquisition tools. Regarding the way of information sharing, it was pointed out the importance to establish a system for information acquisition and sharing in each corp.

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Many damages to water air valves have been reported in the past earthquakes, but the cause of the damage has not been clarified. Therefore, in order to investigate the actual condition and its cause of water air valves damaged by the 2016 Kumamoto Earthquake, we conducted a questionnaire survey on the damage to water air valves of waterworks bureaus in Kyushu region, and analyzed the damage factors of water air valves in Kumamoto City. As the results, it was confirmed that abrupt water pressure change occurring immediately after the earthquake had a great influence on these damage. As the mechanism of abrupt water pressure change, the water hammer occurs by aeration in the air valve which is caused by dynamic pressure at deformed pipe etc. As a result, the air valve can be damaged.

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The present study focuses on examination about field performance of autonomous boat-type robot. This epoch-making robot system allows to measure automatically velocity and discharge in small / middle scale natural rivers. A combination of the camera-tracking system and the Proportional/Integral/Derivative (PID) control could enable the boat-type robot to remain in position against the mainstream. This results in reasonable evaluation of the mean velocity by a duty ratio which corresponds to rotation speed of the screw propeller. We conducted also velocity measurements using electromagnetic velocimetry, and examined quantitatively measurement accuracy by the present robot technique.

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