What is the inundation hazard map (Flood, Inland Water, high tides)?

What is the Inundated hazard map?

　In Yokohama City, the flood hazard map is a compilation of three hazard maps, flood, inland water, and high tides.

About three kinds of hazard map

Flood hazard map

In accordance with 　the Flood Control Law (Article 15 of the Flood Control Law and Article 11 of the Enforcement Regulations of the Act), in order to ensure smooth and prompt evacuation during floods, inundation is expected when rivers are flooded due to rainfall of the largest possible scale, etc. Information on the refuge and other areas is shown in the Flood Inundation Area Map, which shows the estimated flood inundation area and assumed water depth.

Internal waters hazard map

　It is a map that summarizes various information such as the area where inundation from sewer pipes and waterways is expected and the depth of inundation due to the largest possible rainfall (153 mm per hour).
　The inland water hazard map of Yokohama City is not based on the Flood Control Law, but it is created to use it for smooth evacuation actions against flooding and raising awareness of disaster prevention during normal times.
[Reference] About designation of inland water inundation assumption area
For details, please refer to the page of Sewerage and Rivers Bureau Management Promotion Division.
About inland water hazard map

high tides hazard map

Based on 　the Flood Control Law (Article 15 of the Flood Control Law and Article 11 of the Enforcement Regulations of the Act), information on the refuge and other areas is shown in the high tides inundation area map, which shows the estimated depth of water in the event of a high tides, including the largest possible scale, in order to ensure smooth andhigh tideshigh tides.
(Basic setting conditions)
　（1） Assuming the largest typhoon in Japan (the central pressure of the Muroto typhoon)
　（2） We will consider the conditions of typhoon routes, speeds, and radius, and select typhoons that have a greater impact.
　（3） Consider flooding in rivers at the same time as high tides
　（4） Assuming the worst situation, we expect a breach of the dike, etc.
※high tides Inundation Area Map (10 Wards): Tsurumi Ward, Kanagawa Ward, Nishi Ward, Naka Ward, Minami Ward, Hodogaya Ward, Isogo Ward, Kanazawa Ward, Kohoku Ward, Konan Ward
[Reference] About designation of high tides inundation area
For more information, please refer to the following link.
・ Kanagawa homepage "About high tides inundation area along Tokyo Bay coast" (outside site) (outside site)
・ Kanagawa homepage "high tides inundation assumption area map" (outside site) (outside site)

Update information

[October 1, 2024] In response to the review of the high tides inundation area in Kanagawa Prefecture, the hazard map was updated. (New Konan Ward has been added to the high tides Inundation Area.) * There is no change in flood and inland water inundation areas.
[March 1, 2024] Sakae Ward Flood Theard Map has been updated. ※There is no change in the inundation area.
[June 1, 2022] Inundated hazard map in 15 wards of the city (other than Kanagawa Ward, Kanazawa Ward and Sakae Ward) was released.
[September 2021] We opened the flooded hazard map in Sakae Ward.
[August 12, 2021] In Kanagawa Ward hazard map, there was an error in the location of the elementary school (Koyasu Elementary School). [June 28, 2021] Kanagawa Ward, we released the flooded hazard map in Kanazawa Ward.
[September 18, 2020] Information on hazard map in Tsurumi Ward, Kohoku Ward, Midori Ward, Aoba Ward and Tsuzuki Ward has been updated. (There is no change in the inundation area on the map.)

Explanation on the Flood Control Law (explanation of important matters, etc.)

Due to a partial revision of the Enforcement Regulations of the Housing Lots and Buildings Transaction Business Law (enforced on August 28, 2020), the location of residential land or buildings subject to transactions in the flood hazard map created under the Flood Control Law has been newly positioned as an item to explain important matters.
For more information, please click here.
Explanation on the Flood Control Law (explanation of important matters, etc.)

Use the Flood hazard map to create a My Timeline (Evacuation Action Plan)!

　My Timeline is a self-evacuation action plan that has been organized in chronological order in advance according to the family structure and local environment of each person in response to disasters that may occur in the future, such as typhoons and heavy rains.
　Let's check hazard map and create a My Timeline for each person.
　 ◎About my timeline (Yokohama-shi homepage)