All over Japan, damage has occurred from flood from inland waters. Because the measures against urban inundation should be promoted swiftly and economically, the Ministry of Land, Infrastructure, Transport and Tourism has implemented policies to push forward efficient and effective mitigation measures. Such comprehensive policies combine tangible and intangible measures and select prioritized areas for implementation. In June 2020, forecasting methods for probable maximum rainfall were announced, taking heavy rain and climate change into consideration. Furthermore, because a sewer system itself can be damaged from heavy rain, measures have been adopted to make a water-resistant sewerage system. In this manner, various policies in Japan address measures against urban inundation.

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