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<div class="moz-cite-prefix">On 8/6/21 1:40 pm, Yves via Tagging
wrote:<br>
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cite="mid:7119A981-4901-4F93-9F06-3E9212D4492A@mailbox.org">
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What I see when I look for pictures of check dams are structures
that limit the flow. Contrary to what I expect from a weir, the
water goes trough or under.<br>
That would deserve a tag or subtag to make them distinct from
weirs.<br>
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<p>Detention pond? </p>
<p><a class="moz-txt-link-freetext" href="https://wiki.openstreetmap.org/wiki/Tag:basin%3Ddetention">https://wiki.openstreetmap.org/wiki/Tag:basin%3Ddetention</a></p>
<p><br>
</p>
<blockquote type="cite"
cite="mid:7119A981-4901-4F93-9F06-3E9212D4492A@mailbox.org">Regards,<br>
Yves <br>
<br>
<div class="gmail_quote">Le 7 juin 2021 23:28:02 GMT+02:00, Enno
Hermann <a class="moz-txt-link-rfc2396E" href="mailto:enno.hermann@gmail.com"><enno.hermann@gmail.com></a> a écrit :
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<div dir="ltr" class="gmail_attr">On Mon, Jun 7, 2021 at
6:03 PM Mateusz Konieczny via Tagging <<a
href="mailto:tagging@openstreetmap.org"
target="_blank" moz-do-not-send="true">tagging@openstreetmap.org</a>>
wrote:<br>
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<div>
<div><a
href="https://wiki.openstreetmap.org/wiki/File:Check_dam_on_Miya_River_(Jinzu_River).jpg"
target="_blank" moz-do-not-send="true">https://wiki.openstreetmap.org/wiki/File:Check_dam_on_Miya_River_(Jinzu_River).jpg</a><br>
</div>
<div dir="auto">for me it looks like waterway=weir<br>
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<div><br>
</div>
<div>"Solid check dams usually have water flowing over
only a small part of their width and<br>
</div>
<div dir="auto">are designed to handle sudden
increases in water flow."<br>
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<div dir="auto"><br>
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<div dir="auto">Are you sure that thing depicted on
image is not also a weir?<br>
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<div><br>
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<div>I agree that it's not the best example and from this
picture alone it could be hard to tell, although the
construction is typical for check dams. I managed to
find the location and on Google Streetview (<a
href="https://goo.gl/maps/PrtuW627ndkc3NbX7"
target="_blank" moz-do-not-send="true">https://goo.gl/maps/PrtuW627ndkc3NbX7</a>)
or the Japan GSI seamlessphoto imagery (<a
href="https://osm.org/go/7QeF1CmI6" target="_blank"
moz-do-not-send="true">https://osm.org/go/7QeF1CmI6</a>)
the water level is clearly different and water seems to
be flowing only through the bottom of the structure.
Given that, the mountainous terrain and similar
structures nearby I would say it is clearly a check dam.<br>
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<div> </div>
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<div dir="auto">And "designed to handle sudden
increases in water flow." is applicable to<br>
</div>
<div dir="auto">any sanely constructed waterway
engineering.<br>
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<div><br>
</div>
<div>"sudden and significant" might fit better. Often
those streams are normally only a trickle or even
completely dry but then can see sudden debris flows like
this: <a
href="https://www.youtube.com/watch?v=2Rfuoylv34k"
target="_blank" moz-do-not-send="true">https://www.youtube.com/watch?v=2Rfuoylv34k</a>
This is different from floods on already larger rivers.<br>
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<div> </div>
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<div>
<div dir="auto">See <a
href="https://en.wikipedia.org/wiki/File:Culverts_under_yass_river_walkway_weir.JPG"
target="_blank" moz-do-not-send="true">https://en.wikipedia.org/wiki/File:Culverts_under_yass_river_walkway_weir.JPG</a><br>
</div>
<div dir="auto">on Wikipedia weir page.<br>
</div>
<div dir="auto"><br>
</div>
<div dir="auto">Or <a
href="https://en.wikipedia.org/wiki/File:Grial%C3%ABces_cuecenes.jpg"
target="_blank" moz-do-not-send="true">https://en.wikipedia.org/wiki/File:Grial%C3%ABces_cuecenes.jpg</a>
with description<br>
</div>
<div dir="auto">"During periods of high river flow,
this nineteenth century weir of porphyry stone on <br>
</div>
<div dir="auto">a creek in the Alps would have
significantly more water flowing over it."<br>
</div>
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<div><br>
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<div>An early example of a check dam? ;) I'd say very
small structures or simple constructions that can't be
clearly identified as a check dam may just be tagged as
weirs.</div>
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