OpenStreetMap

intermittent streams in arid environment

Posted by TorCguy on 12 August 2014 in English (English)

I have been shown the error of my ways. So I went back and changed those streams that had been marked as 'intermittent=dry' back to '=yes' as per standard usage. If I missed any, let me know.

It was also pointed out that I could use 'waterway=wadi' but this does not symbolize, and only shows up as a black line. Thus I hesitate to use this combination. But, in much of eastern Sierra County, this would be appropriate. Any thoughts?

It would be nice if OSM would use a dashed line when streams are marked as 'intermittent=yes' because it looks a little strange to have all these solid blue lines out here in the desert.

When I made maps for Dept of Defense, we categorized drainage with three levels of flow regime: perennial, intermittent and ephemeral. This is because the dry streams (wadi, wash, arroyo) have distinctly different physical characteristics than intermittent streams.

BTW: I finally got smart and used the map function to nail down my location. :)

Location: Kopra Street, Truth or Consequences, Sierra County, New Mexico, 87901, United States of America

Comment from 4rch on 12 August 2014 at 05:54

http://wiki.openstreetmap.org/wiki/Tag:waterway%3Dwadi http://wiki.openstreetmap.org/wiki/Tagging_for_the_renderer "The basic good practice principle is that you avoid using incorrect tags, or otherwise skewing the data you enter, to make things show up in a specific way on the map rendering."

https://github.com/gravitystorm/openstreetmap-carto/issues/805

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Comment from imagico on 12 August 2014 at 10:15

A more fine grained characterization of intermittent waterways makes only limited sense since it can rarely be expected from the mapper to know how frequently a stream carries water. You could add ephemeral=yes in addition to intermittent=yes if you have this information. Also you could have intermittent=yes and seasonal=no to indicate there is no seasonal pattern.

Generally the characterization 'ephemeral' is often extremely vague - it can mean anything from 'frequent but short presence of water for example after rain' to 'no water for decades and possibly permanently dry due to climate change'.

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Comment from Sanderd17 on 12 August 2014 at 12:37

As you're supposed to map regions you know (and don't do armchair mapping, except in some cases), a mapper can be expected to know how often there's water streaming there.

But as there are not a lot of populated places where streams are often dry, these tags aren't used very often.

If you know good worldwide definitions for all sorts of intermittent streams, with re-use of, or coherence with existing tags , I can only suggest you make a proposal. ( http://wiki.openstreetmap.org/wiki/Proposed_features )

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