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<div class="moz-cite-prefix">On 25/05/18 15:00, Nick Bolten wrote:<br>
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<div>If I understand this proposal right, the goal of this tag
is to provide more specific information for the general
likelihood of whether a water feature (only rivers?) exists:
when it comes and goes every days.</div>
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The tag provides mapper a way of tagging rivers and streams that is
presently not available. <br>
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<div>This sounds like there are two pieces of information that
are desirable to map:</div>
<div>- What is the frequency of flow/presence?</div>
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That will vary .. year to year and decade to decade ... to much
change? <br>
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<div>- Does this frequency vary over seasons?</div>
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This too will vary. <br>
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<div>These seem like questions that deserve separate tags, for
flexibility, and could benefit from a 'subtag' approach. Let's
say you want to describe a river that always has current in
the spring and summer, is intermittent in the fall, and has no
flow in the winter. This could look like:</div>
<div><br>
</div>
<div>intermittent=yes;ephemeral;no</div>
<div>intermittent:ephemeral=autumn</div>
<div>intermittent:yes=winter</div>
<div>
<div>intermittent:no=spring;summer</div>
</div>
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<br>
Intermittent does not equal ephemeral.<br>
<br>
At present in OSM the tag to indicate an intermittent flow that
only occurs in winter is <br>
intermittent=winter<br>
<br>
The proposal for ephemeral flow in autumn would be <br>
ephemeral=autumn <br>
<br>
Combining these would give <br>
intermittent=winter<br>
ephemeral=autumn <br>
<br>
I would think that is easy enough to understand and matches the
present tagging scheme in use. <br>
<br>
<br>
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<div>The first tag declares the frequency, but doesn't specify
when each tag applies. The other 3 describe how this frequency
varies over seasons. The presence of more than one value for
`intermittent` would be a hint for incremental mapping/QA:
there should be one
`intermittent:<value>=<season>` for every value in
`intermittent`. Tagging a single water feature as always
`ephemeral` would also be simple and get combined with the
seasonal tag: `intermittent=ephemeral`
`seasonal=<season>`.</div>
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The intermittent tag already exists .. do you want to change it? <br>
<br>
And what if the stream has a seasonal flow in say winter and an
ephemeral flow possible in spring? <br>
For this proposal this would be tagged <br>
seasonal=winter<br>
ephemeral=spring <br>
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<div>I also have a follow-up about the use cases for this data.
For example, for the cases I can imagine off the top of my
head (scientific, humanitarian), it's valuable to know how
stale the data is, how the person collecting it determined the
value (memory, general impression as a local?), and ideally
have a yearly report of flow (in some form or another), and so
a wikidata key or external db may serve your use case better.
Unfortunately, this raises a lot of hard questions about
linking OSM and time series data that I don't think are
solved, but it the discussion could be valuable in itself.</div>
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<br>
The same can be said for roads. how stale is that data .. etc.<br>
<br>
The present tagging has no entry for ephemeral. None. <br>
If you want more data .. such as flow rates .. then put it forward.
It would need to include perennial flows, as well as seasonal, etc.
<br>
I don't think anyone wants that data in OSM ... yet. <br>
<br>
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<div>Nick</div>
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<div class="gmail_quote">
<div dir="ltr">On Mon, May 21, 2018 at 3:35 PM Warin <<a
href="mailto:61sundowner@gmail.com"
moz-do-not-send="true">61sundowner@gmail.com</a>>
wrote:<br>
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<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">Hi,<br>
<br>
Following from the discussion on "Seasonal,
intermittent, and ephemeral <br>
water tags" I have created this proposal.<br>
<br>
<br>
Hopefully the definition is tight enough that it
excludes intermittent, <br>
seasonal and any other thing that is not ephemeral.<br>
<br>
I have also included a guide on determination so that
mappers can see <br>
how to determine if something is ephemeral.<br>
<br>
<br>
So here it is ...<br>
<br>
<a
href="https://wiki.openstreetmap.org/wiki/Proposed_features/ephemeral"
rel="noreferrer" target="_blank"
moz-do-not-send="true">https://wiki.openstreetmap.org/wiki/Proposed_features/ephemeral</a><br>
<br>
<br>
Is it clear? Do you understand it?<br>
<br>
<br>
Would you use it? If so where?<br>
<br>
<br>
Any thing else?<br>
<br>
<br>
<br>
<br>
<br>
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