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Execerpt of the ICHARM publication Local Disaster Management and Hazard Mapping (Oct. 2008)

1. Outline of Flood Hazard Mapping

1.1 What is Flood Hazard Map?
In Japan, in the sense of legislation, Flood Hazard Map(FHM) is defined as a map
1) with anticipated inundation area
2) with information for safe evacuation
3) made by municipality.

However, a map of past inundation with/without information for safe evacuation can also be called “FHM”. It can be considered that the essence of FHM is “hazard” of floods. Then, so-called “flood risk map” can also be included in FHM.
The web page of “Terminology of disaster risk reduction” in ISDR(UN/International Strategy for Disaster Reduction) does not have “(Flood) Hazard Map” or “(Flood) Risk Map”. See the following site.
In EU, Directive 2007/60/EC on the assessment and management of flood risks entered into force on 26 November 2007. The Directive includes “flood hazard maps” or “flood risk maps”. See the following site.

It is written in Chapter III, that Flood hazard maps shall cover the geographical areas which could be flooded according to the following scenarios:
(a) floods with a low probability, or extreme event scenarios;
(b) floods with a medium probability (likely return period ≥ 100 years);
(c) floods with a high probability, where appropriate.

For each scenario the following elements shall be shown:
(a) the flood extent;
(b) water depths or water level, as appropriate;
(c) where appropriate, the flow velocity or the relevant water flow.