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Map of 'imminent flooding' under development to urge prompt evacuation

With the levees of the Kinugawa River (top right) having burst, a residential area in the Ibaraki Prefecture city of Joso is seen flooded in this photo taken from a Mainichi Shimbun helicopter on Sept. 10, 2015. (Mainichi)

A land ministry research institute is developing a system of monitoring rivers in real time and sharing information on potential flooding with local governments and residents to help people evacuate before levees break or rivers overflow.

    The "Kozui kikendo mieruka project (Project for Sharing Flood Disaster Risk with Local Governments and Local Communities)," launched by the Ministry of Land, Infrastructure, Transport and Tourism (MLIT)'s National Institute for Land and Infrastructure Management (NILIM) in Tsukuba, Ibaraki Prefecture, is set to be completed in fiscal 2018.

    According to MLIT, approximately 2,000 rivers across the country are currently being monitored at some 6,600 water-level checkpoints managed by the ministry and other entities. When water levels rise, information is disseminated on whether checkpoints -- in increments of several to about a dozen kilometers -- are flooded, are in imminent danger of flooding, should be watched with great vigilance, or should be watched with caution.

    NILIM, however, determined that it was too difficult for local municipalities with limited staff to comprehensively assess the dangers of rising water levels and issue appropriate evacuation orders or advisories to residents in their jurisdictions. The institute is therefore in the process of developing technology that would make it visibly clear on a map what areas are in danger of being immersed in water. The plan is to use easily understood expressions such as "1 meter until water reaches top of levee" and "water levels rose 2 meters in 1 hour."

    MLIT hopes that the new system will not only help local governments issue evacuation orders and advisories, but also assist residents in making their own decisions to evacuate voluntarily. The major challenge is how to provide the information to individual residents.

    There are two cases fresh in people's minds that could have benefitted from the technology being developed: the 2015 disaster in which dikes along the Kinugawa River burst, leaving around 4,300 residents to be helicoptered out or rescued through other methods because of a delay in the issuance of evacuation orders, and the heavy rains that hit Hokkaido in 2016, in which evacuation orders and recommendations were issued for some 147,000 people, but only around 11,000 people actually evacuated.

    It was the damage wrought by the flooding of the Kinugawa River that prompted MLIT to begin issuing emergency alerts via email regarding rivers under the central government's jurisdiction. The "Kozui kikendo mieruka project" now under development will also seek new ways of relaying pertinent information to local governments and residents.

    "If people can see how rivers are rising near their residences with a single glance at a map, they can easily understand whether they will be affected by flooding," says Masaki Kawasaki, head of NILIM's Water Cycle Division. "We hope to make the new system one that can be used for evacuation drills as well, which will help in encouraging people to evacuate when the situation calls for it."

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