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Available languages — Key:flood_prone
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Public-images-osm logo.svg flood_prone
Whether or not the feature is likely to flood after very heavy rain. Edit or translate this description.
Group: Properties
Used on these elements
may be used on nodesmay be used on waysmay be used on areasmay be used on relations
Useful combination
See also
Status: in use

This tag is used on an area or way, that is prone to flooding. This is mostly applicable to roads that go under water after heavy rains. Flooded roadways are often very dangerous to cross and many people die each year as a result.

A [W] Floodplain is an area around waterway where it could break it's banks and flood the surrounding area, A [W] Floodway is a crossing along a waterway or a floodplain.

Mapping Waterway Crossings

To map a simple floodway crossing that does not have a bridge-like structure. Apply a tunnel=culvert tag to the waterway, and put flood_prone=yes on the intersecting highway.

Waterway Floodway Crossing.png

Mapping Flood Prone Bridges

For a flood prone bridge, you should ensure a bridge=* tag is on the relevant highway and add flood_prone=yes. Nothing really needs to be done to the waterway since the bridge is a structure above the waterway.

Flood Prone Bridge.png

Mapping Flood Prone Highways

If the area is surrounded by flood plains or is otherwise at risk of flooding. You should apply a flood_prone=yes to the entire way that is likely to go underwater.

Flood Prone Area.png

General Situation


Photos were taken south of Barellan, in the Mirrool Creek floodplain.


The above photos are of the Gwydir highway east of Moree


While it is preferable to tag the entire way that is likely to go under water, if this information isn't known you can tag a node as flood_prone=yes as this may help routing software to avoid potentially hazardous crossings if there has been heavy rain.


Flood prone areas don't have water across them 99.9% of the time, so there isn't any perceived benefit in rendering these areas most of the time.

Emergency services may find it useful to have their own flood mapping that highlights these and similar tags, but this is a special use case.



Similar Tag Ideas

  • It might be useful to tag the markers that indicate depth of water when flooded, although similar markers can be found along river banks and tidal water areas
  • It might be useful to tag how often flooding gets or covers a certain area, eg once in 100 years.

See Also