[Tagging] Adding 'flood' as value to the key 'hazard' (to be used in combination with the tag boundary=hazard)

[Andy Townsend]

On 15/06/2023 20:47, Jez Nicholson wrote:
> Whilst it is a great idea to capture local knowledge about flooding, 
> especially where it is currently not available, I am concerned that 
> this doesn't have on-the-ground verification.

I don't think that anyone has suggested that - at least not in this thread?

The original email said "The location and extent of these hazard areas 
is often well known by local communities with knowledge of past events."

When I talked about "what is currently flooded based on current measured 
level and previous observations"I meant exactly that - recording that 
when a river level at a known point reads X, land at Y (in the vicinity 
of X) will also be flooded.

>
> Flood risk areas are predictions generated via modelling software and 
> it depends on which software you use, and the quality of the input data.

Indeed - the Environment Agency in the UK (and other agencies elsewhere) 
make extensive use of this sort of model, but I suspect that mapping 
this sort of thing goes  bit beyond what can usefully done within OSM, 
though of course it can be combined with OSM data by a data consumer to 
create "risk maps".

>
> The current hazardous areas get away with it by mapping areas marked 
> out by signage. Sure, the signs may have been placed following 
> predictions, but they are physically there to be seen.
>
I suspect that this isn't true for all "boundary=hazard" in OSM at the 
moment (picking one at random, the signage for 
https://www.openstreetmap.org/way/500428513 and the wider 
https://www.openstreetmap.org/relation/15680620 doesn't look especially 
extensive - see 
https://www.abc.net.au/radio/programs/australia-wide/australia-wide/13490888#:~:text=Wittenoom%20is%20the%20largest%20contaminated,site%20in%20Western%20Australia%27s%20Pilbara. 
)

Best Regards,

Andy
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