<div dir="ltr">I would also add that "water=reservoir" is a sub-tag of "natural=water"; while "landuse=reservoir" is a tag that can go alone by itself. The main thing is that the second scheme is older than the first, and thus still more used. <div>Looking at the proposal to "simplify water tagging" that was approved a few years ago ( <a href="https://wiki.openstreetmap.org/wiki/Proposed_features/Water_details">https://wiki.openstreetmap.org/wiki/Proposed_features/Water_details</a> ), the new scheme is to use <b>natural=water + water=*</b> on most of the water related features. <br><div><div><br></div><div>For the reservoir/basin that don't always contain water (<b>especially for storm water retention !</b>), we already have another tag : "landuse=basin" that is for <i>" An area of land artificially graded to hold water." </i> so it already cover this part and the sub-tag here are clearly made to describe storm water retention/infiltration and some other artificial uses like that.</div><div><span style="background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline"><font face="sans-serif"><span style="font-size:14px"><a href="https://wiki.openstreetmap.org/wiki/Tag:landuse%3Dbasin">https://wiki.openstreetmap.org/wiki/Tag:landuse%3Dbasin</a></span></font><br></span></div></div><div><span style="background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline"><font face="sans-serif"><span style="font-size:14px"><br></span></font></span></div><div><span style="background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline"><font face="sans-serif"><span style="font-size:14px">Thus, the landuse=reservoir tag is mostly an older scheme that still exist and evolve as there are a lot of use in the database. Maybe should it be discouraged to simplify the water tagging ? At the end, it doesn't really matter that much for data users as it is only two schemes that say exactly the same things (with the same sub-tag "reservoir_type=*"), it is more a complexity in the database that could probably be avoided.</span></font></span></div></div></div><div class="gmail_extra"><br><div class="gmail_quote">2018-07-19 10:08 GMT+02:00 Warin <span dir="ltr"><<a href="mailto:61sundowner@gmail.com" target="_blank">61sundowner@gmail.com</a>></span>:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF"><div><div class="h5">
<div class="m_3607227645718257884moz-cite-prefix">On 19/07/18 16:53, Mateusz Konieczny
wrote:<br>
</div>
<blockquote type="cite">
18. Lipiec 2018 16:02 od <a href="mailto:eric@eric-poehlsen.de" rel="noopener noreferrer" target="_blank">eric@eric-poehlsen.de</a>:<br>
<br>
<blockquote class="m_3607227645718257884tutanota_quote" style="border-left:1px solid #93a3b8;padding-left:10px;margin-left:5px">
<div class="m_3607227645718257884WordSection1"><font face="Courier New" size="2"><span></span></font>
<p class="MsoNormal"><font face="Courier New" size="2"><span><font face="Courier New">The present OSM
meaning of landuse=basin is "An area of land
artificially graded to hold water."</font><br>
<font face="Courier New"><a href="https://wiki.openstreetmap.org/wiki/Tag:landuse%3Dbasin" rel="noopener noreferrer" target="_blank">https://wiki.openstreetmap.<wbr>org/wiki/Tag:landuse%3Dbasin</a></font><br>
<font face="Courier New">This does not distinguish it
from water=reservoir</font><br>
<font face="Courier New">OSM defined as "A reservoir or
artificial lake used to store water."</font><br>
<font face="Courier New"><a href="https://wiki.openstreetmap.org/wiki/Tag:water%3Dreservoir" rel="noopener noreferrer" target="_blank">https://wiki.openstreetmap.<wbr>org/wiki/Tag:water%3Dreservoir</a></font><br>
<br>
<br>
<span class="m_3607227645718257884mw-content-ltr"><span style="background:#eeeeff">I think it should have the word
"temporarily" add to read </span></span><br>
<br>
<br>
<span class="m_3607227645718257884mw-content-ltr"><span style="background:#eeeeff">"An area of land artificially graded to
temporarily hold water."</span></span><br>
<br>
<br>
<span class="m_3607227645718257884mw-content-ltr"><span style="background:#eeeeff">I see it as similar to the bathroom basin -
it holds water, but not all the time. </span></span></span></font><br>
<br>
<font face="Courier New" size="2"><span style="font-size:10.0pt">Thoughts? </span></font></p>
</div>
</blockquote>
<p><br>
</p>
<p>Have you checked what is mapped? If mappers use both tags in
the same way then <br>
</p>
<p>redefining them on wiki without resurveying most of them is
pointless.</p>
</blockquote>
<br></div></div>
I have not 'refined' them. I have simply stated the usual
configuration. <br>
It is done to help mappers differentiate between them. <br>
<br>
As both are rendered the same the effect is negotiable. <br>
<br>
Dams are usually seen in imagery. And the larger of them are mapped.
So that can confirm that no reservoirs are mapped as basins. <br>
<br>
I would expect reservoirs have been mapped for some time in OSM and
basins only recently so there will be a fair few basins mapped as
reservoir. <br>
This is a practice of 'best fit' and at worst 'tagging for the
render'. I possibly have a few of them... <br>
<br>
If future renders distinguish between them then mappers will have
motivation to correct any errors. <br>
At the moment that motivation is very small. <br>
<br>
Where someone has used both tags on the same object there is a
problem... which is it? <br>
In that case I would first consult the history - what was it
originally tagged, and then look at imagery for possible
confirmation. <br>
If the imagery is poor then I'd go with the original mapper.
Contacting the relevant mappers is also a possibility. <br>
<br>
</div>
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<br></blockquote></div><br></div>