<div dir="ltr"><div>Hi all,</div><div><br></div><div>Many thanks for the responses and feedback! :) Here a few comments:</div><div><br></div><div>- The aim would be to collect information on historic floods and community knowledge of hazard exposure. I work for the Red Cross Climate Centre on hazard assessments in typically data scarce areas (e.g. East Sudan). While in many western countries most flood areas have high-quality flood maps derived from scientific flood models, in those areas we lack this information. There are of course global flood models, but they lack verification and validation on a local level in many areas I am looking into. Especially there, being able to capture information of historic, true flood extents and community knowledge is crucial to fill those data gaps and improve disaster risk reduction efforts.</div><div>- I reviewed existing tags and tag info, but I thought it lacked some uniformity. While with boundary=hazard and the added value there already exist approved natural hazard tags which I find make more sense to add in here.</div><div>- The OpenHazrdMap was set up as Wiki Page but wasn`t followed through and no voting or approval for suggested tags was carried out.</div><div><br></div><div>Please let me know what you think, and whether you would approve to adding the flood value 'flood' as value to the key 'hazard' (to be used in combination with the tag boundary=hazard).</div><div><br></div><div>All the best and many thanks,</div><div>Cornelia<br></div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, Jun 16, 2023 at 9:13 AM Jez Nicholson <<a href="mailto:jez.nicholson@gmail.com">jez.nicholson@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto">Noted.<div dir="auto"><br></div><div dir="auto"><br></div><div dir="auto">I was [over]reacting to the section from OP about return periods.</div><div dir="auto"><br></div><div dir="auto">If this proposal is specifically about areas of historical flooding rather than areas deemed at risk of flooding then they *can* be observed on-the-ground.</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, 16 Jun 2023, 01:08 Andy Townsend, <<a href="mailto:ajt1047@gmail.com" target="_blank">ajt1047@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div>
<div>On 15/06/2023 20:47, Jez Nicholson
wrote:<br>
</div>
<blockquote type="cite">
<div dir="auto">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.</div>
</blockquote>
<p>I don't think that anyone has suggested that - at least not in
this thread? <br>
</p>
<p>The original email said "The location and extent of these hazard
areas is often well known by local communities with knowledge of
past events."<font size="2"><span style="font-family:Arial;color:rgb(0,0,0);background-color:transparent;font-weight:400;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"></span></font></p>
<p><font size="2"><span style="font-family:Arial;color:rgb(0,0,0);background-color:transparent;font-weight:400;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">When I talked about </span></font>"what
is currently flooded based on current measured level and previous
observations"<font size="2"><span style="font-family:Arial;color:rgb(0,0,0);background-color:transparent;font-weight:400;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"></span></font>
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.<br>
</p>
<blockquote type="cite">
<div dir="auto">
<div dir="auto"><br>
</div>
<div dir="auto">Flood risk areas are predictions generated via
modelling software and it depends on which software you use,
and the quality of the input data.</div>
</div>
</blockquote>
<p>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".<br>
</p>
<blockquote type="cite">
<div dir="auto">
<div dir="auto"><br>
</div>
<div dir="auto">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.</div>
<div dir="auto"><br>
</div>
</div>
</blockquote>
<p>I suspect that this isn't true for all "boundary=hazard" in OSM
at the moment (picking one at random, the signage for
<a href="https://www.openstreetmap.org/way/500428513" rel="noreferrer" target="_blank">https://www.openstreetmap.org/way/500428513</a> and the wider
<a href="https://www.openstreetmap.org/relation/15680620" rel="noreferrer" target="_blank">https://www.openstreetmap.org/relation/15680620</a> doesn't look
especially extensive - see
<a href="https://www.abc.net.au/radio/programs/australia-wide/australia-wide/13490888#:~:text=Wittenoom%20is%20the%20largest%20contaminated,site%20in%20Western%20Australia%27s%20Pilbara" rel="noreferrer" target="_blank">https://www.abc.net.au/radio/programs/australia-wide/australia-wide/13490888#:~:text=Wittenoom%20is%20the%20largest%20contaminated,site%20in%20Western%20Australia%27s%20Pilbara</a>.
)<br>
</p>
<p>Best Regards,</p>
<p>Andy<br>
</p>
</div>
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