<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">ajt1047@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;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" target="_blank" rel="noreferrer">https://www.openstreetmap.org/way/500428513</a> and the wider
      <a href="https://www.openstreetmap.org/relation/15680620" target="_blank" rel="noreferrer">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" target="_blank" rel="noreferrer">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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