On 21/05/18 19:16, cleary wrote:
I am struggling with how to use "ephemeral" rather than the "intermittent" tag,
particularly when it comes to on-the-ground verification.
Good point. However ...
If the Todd River is ephemeral then by extrapolation other waterways in the
surrounding area would be too.
Knowing the weather patterns where rain fall is nothing for years and then a
few years worth within some days would suggest that
these areas have ephemeral water ways too. So, how is you knowledge of rainfall
patterns? :)
I have travelled in some rural and outback areas in western NSW and Queensland
and, to a lesser extent, in South Australia. I also regularly look at
satellite imagery. If I see a waterway or lake without water, I am comfortable
to add the intermittent tag. But I don't see every waterway and lake often
enough to know how often the water flows. And satellite imagery is just a
snapshot at one moment, perhaps several years ago. How can one expect to verify
the frequency or duration of water flow? Another concern is that the total area
of a lake may be covered with water only occasionally but half the area may be
covered in water much more of the time. Do we try to work out which part of the
lake is ephemeral and which is intermittent?
When Lake Eye has some water in it .. where it is will depend on which way the
wind is blowing .. it is that flat due to the salt layer.
However Lake Eyre would be intermittent .. as there is water in it or more than
5 weeks .. when it is full,
so it does not comply with the ephemeral 'majority of the time' .. at least for
me.
I understand why it may be useful to map water areas differently if they are
not always filled with water. But trying to pictorially represent the dimension
of time on a two-dimensional map and somehow show multiple degrees of absence
of water, has me puzzled.
I don't think we would try to map roads differently according to whether they
carry traffic all the time, some of the time, or just occasionally.
I will work with whatever the community agrees, but I need help to understand
how to verify ephemeral as distinct from intermittent when mapping waterways
and lakes.
That help? I'll add it to the ephemeral page.
A side issue ... the meaning of 'intermittent' is poorly defined on the OSM
wiki .. and some have taken it to be so similar to seasonal they are applying
both tags.
I think seasonal is not rendered and intermittent is .. and that could be
motivation for some to apply the intermittent tags to the seasonal waterways...
On Mon, May 21, 2018, at 11:10 AM, Warin wrote:
I have started a draft for ephemeral.
https://wiki.openstreetmap.org/wiki/Proposed_features/ephemeral
On 19/05/18 12:08, Ian Sergeant wrote:
On 19/05/18 11:38, Ian Sergeant wrote:
flow=ephemeral, maybe. water-presence=ephemeral?
On 19 May 2018 at 11:44, Warin <[email protected]> wrote:
'ephemeral=yes' matches the present use of 'intermittent=yes'. I like at
least some consistency in the tagging.
I think you picked the wrong mapping project :-)
Yep. landuse=grass ... stupid.
The issue here of course, is that the next tag will something=yes.
Ugliness. Best to fix it now.
The properties keys are all this way. So I follow the crowd, as
convincing the crowd is probably required.
Changing all of them would be a mammoth task. Changing one tag ..
landuse=grass ... is just a little less of a challenge.
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