Re: [Tagging] Modelling the relation between a waterstream and one of its resurgence

[Richard]

On Tue, Sep 15, 2015 at 04:08:12PM +0200, David Marchal wrote:
> 
> 
> > Date: Fri, 11 Sep 2015 14:18:37 +0200
> > From: ricoz@gmail.com
> > To: tagging@openstreetmap.org
> > Subject: Re: [Tagging] Modelling the relation between a waterstream and one 
> > of its resurgence
> > missing data should not prevent the mapping of known good data. If it has 
> > been established as 
> > the "main route" than it is fine to map that. We have rivers with side 
> > channels and branches
> > that aren't completely mapped either.
> 
> Yes, but if I try to map these waterways as a single one, it will no longer 
> represent the official modelling of the stream, which is: two separate 
> streams, one meeting the other on a downstream section. Modelling them as one 
> would destroy the current modelling, so how can I map the connection without 
> altering the current data?

in that case you would need to decide between real world and official modelling.

Although drawing a waterway-line between them does not necesarilly mean they 
are no
longer separate. Maybe connect them with a way and tag it as 
waterway=carstic_flow?

> > Not much different from confluence points of large rivers?
> Well, the stream feeded by the other is 126 km long, and it's spring, 
> resurgence of the other, is around 50 km away from the second so it can't be 
> just modelled as a branch of the other.  
it happens quite often that river change names along their course, how is that 
done
with the river relation? Maybe something similar could be done here?

Richard

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Re: [Tagging] Modelling the relation between a waterstream and one of its resurgence

[David Marchal]

> Date: Fri, 11 Sep 2015 14:18:37 +0200
> From: ricoz@gmail.com
> To: tagging@openstreetmap.org
> Subject: Re: [Tagging] Modelling the relation between a waterstream and one 
> of its resurgence
> missing data should not prevent the mapping of known good data. If it has 
> been established as 
> the "main route" than it is fine to map that. We have rivers with side 
> channels and branches
> that aren't completely mapped either.

Yes, but if I try to map these waterways as a single one, it will no longer 
represent the official modelling of the stream, which is: two separate streams, 
one meeting the other on a downstream section. Modelling them as one would 
destroy the current modelling, so how can I map the connection without altering 
the current data?
> Not much different from confluence points of large rivers?
Well, the stream feeded by the other is 126 km long, and it's spring, 
resurgence of the other, is around 50 km away from the second so it can't be 
just modelled as a branch of the other.___
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Re: [Tagging] Modelling the relation between a waterstream and one of its resurgence

[David Marchal]

Yes, I indeed thought of a karst system, but specifically of the case when one 
spring, even if it feeds a stream of its own, is in fact a resurgence of a 
partial loss of another stream.

From: j...@jfeldredge.com
To: tagging@openstreetmap.org
Date: Thu, 10 Sep 2015 17:30:24 -0500
Subject: Re: [Tagging] Modelling the relation between a waterstream and one 
of its resurgence









Are you referring to a stream
that, at some point, goes underground, then re-emerges to the surface at a
downstream point? These are common on karst terrain.
-- 

John F. Eldredge -- j...@jfeldredge.com

"Darkness cannot drive out darkness; only light can do that. Hate cannot drive 
out hate; only love can do that."
-- Martin Luther King, Jr.




On
September 9, 2015 1:56:27 AM David Marchal  wrote:

Hello, there.
I wondered: when a
waterstream is known to be, instead of a real, separated waterstream,
merely a resurgence of another one, how should the link between them be
modelled? Which tags should I use, and in which relation? Should I tag the
resurgence by itself?
Hoping you can
help,
Regards.  
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Re: [Tagging] Modelling the relation between a waterstream and one of its resurgence

[Richard]

On Wed, Sep 09, 2015 at 05:25:52PM +0200, David Marchal wrote:
> > map the underground stream if possible.
> As I don't know where the intake from the first stream is, I think I can't 
> map it this way. Besides, wouldn't that make the link exclusive, i.e. tell 
> that the water only comes from one point and exits at another? If so, I can't 
> either, as no-one can be sure of that in karstic systems: you can be sure 
> that a ponor feeds a spring, but not that only this single ponor feeds only 
> this particular spring, as there can be other ponors feeding this spring, and 
> other springs fed by this ponor.

missing data should not prevent the mapping of known good data. If it has been 
established as 
the "main route" than it is fine to map that. We have rivers with side channels 
and branches
that aren't completely mapped either.

The missing data on the intake is a problem in this particular case though.

> The problem is that the resurgence is renowned as a separate river, even if 
> the link with the losing stream is well known, and those rivers both has 
> their waterway relation. How can I map the link without messing with the 
> separate waterway relations ? 

Not much different from confluence points of large rivers?

Richard

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Re: [Tagging] Modelling the relation between a waterstream and one of its resurgence

[John Eldredge]

Are you referring to a stream that, at some point, goes underground, then 
re-emerges to the surface at a downstream point? These are common on karst 
terrain.


--
John F. Eldredge -- j...@jfeldredge.com
"Darkness cannot drive out darkness; only light can do that. Hate cannot 
drive out hate; only love can do that." -- Martin Luther King, Jr.




On September 9, 2015 1:56:27 AM David Marchal  wrote:


Hello, there.
I wondered: when a waterstream is known to be, instead of a real, separated 
waterstream, merely a resurgence of another one, how should the link 
between them be modelled? Which tags should I use, and in which relation? 
Should I tag the resurgence by itself?

Hoping you can help,
Regards.


--
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[Tagging] Modelling the relation between a waterstream and one of its resurgence

[David Marchal]

Hello, there.
I wondered: when a waterstream is known to be, instead of a real, separated 
waterstream, merely a resurgence of another one, how should the link between 
them be modelled? Which tags should I use, and in which relation? Should I tag 
the resurgence by itself?
Hoping you can help,
Regards.  ___
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Re: [Tagging] Modelling the relation between a waterstream and one of its resurgence

[Richard]

On Wed, Sep 09, 2015 at 08:55:44AM +0200, David Marchal wrote:
> Hello, there.
> I wondered: when a waterstream is known to be, instead of a real, separated 
> waterstream, merely a resurgence of another one, how should the link between 
> them be modelled? Which tags should I use, and in which relation? Should I 
> tag the resurgence by itself?

map the underground stream if possible. I dont't think there is
a standard way to do it but location=underground might work. Some
people used variations of tunnel=* with additional tags for cave.

  http://wiki.openstreetmap.org/wiki/Cave
has some info and discussion on the talk page

If mapping the underground stream is not an option use the quite normal
relation waterway.

Richard

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Re: [Tagging] Modelling the relation between a waterstream and one of its resurgence

[Jo]

I would say that we need a new type of relation for that.

Jo

2015-09-09 17:25 GMT+02:00 David Marchal :

> > map the underground stream if possible.
>
> As I don't know where the intake from the first stream is, I think I can't
> map it this way. Besides, wouldn't that make the link exclusive, i.e. tell
> that the water only comes from one point and exits at another? If so, I
> can't either, as no-one can be sure of that in karstic systems: you can be
> sure that a ponor feeds a spring, but not that only this single ponor feeds
> only this particular spring, as there can be other ponors feeding this
> spring, and other springs fed by this ponor.
>
> Anyway, I can remember of some locations where a stream is known to be
> undergroud, and that it is the same stream all along, running underground
> below its dry bed during summer and filling it only during winter, so that
> will be useful.
>
> > If mapping the underground stream is not an option use the quite normal
> > relation waterway.
>
> The problem is that the resurgence is renowned as a separate river, even
> if the link with the losing stream is well known, and those rivers both has
> their waterway relation. How can I map the link without messing with the
> separate waterway relations ? By creating a super-relation ? I don't want
> to FUBAR the data.
>
> Regards.
>
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>
>
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Re: [Tagging] Modelling the relation between a waterstream and one of its resurgence

[David Marchal]

> map the underground stream if possible.
As I don't know where the intake from the first stream is, I think I can't map 
it this way. Besides, wouldn't that make the link exclusive, i.e. tell that the 
water only comes from one point and exits at another? If so, I can't either, as 
no-one can be sure of that in karstic systems: you can be sure that a ponor 
feeds a spring, but not that only this single ponor feeds only this particular 
spring, as there can be other ponors feeding this spring, and other springs fed 
by this ponor.
Anyway, I can remember of some locations where a stream is known to be 
undergroud, and that it is the same stream all along, running underground below 
its dry bed during summer and filling it only during winter, so that will be 
useful.
> If mapping the underground stream is not an option use the quite normal
> relation waterway.

The problem is that the resurgence is renowned as a separate river, even if the 
link with the losing stream is well known, and those rivers both has their 
waterway relation. How can I map the link without messing with the separate 
waterway relations ? By creating a super-relation ? I don't want to FUBAR the 
data.
Regards.  ___
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Re: [Tagging] Modelling the relation between a waterstream and one of its resurgence

[David Marchal]

> Which is why mapping this is not really within the scope of OSM - 
> natural underground waterflows are inherently non-verifiable.  

Well, maybe I should let that down, then, or put the data in the description 
field; this way, I won't mess with the OSM data, but they'll be there if 
someone is interested.

> You can and should map the surface phenomena related to the underground 
> water flow of course - ponors, dolines, karst springs and other stuff.

In fact, I'm drafting a proposal on this, which is why I asked this, to know if 
I could put something consistent on this matter in the proposal.

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Re: [Tagging] Modelling the relation between a waterstream and one of its resurgence

[Christoph Hormann]

On Wednesday 09 September 2015, David Marchal wrote:
>
> As I don't know where the intake from the first stream is, I think I
> can't map it this way. Besides, wouldn't that make the link
> exclusive, i.e. tell that the water only comes from one point and
> exits at another? If so, I can't either, as no-one can be sure of
> that in karstic systems: you can be sure that a ponor feeds a spring,
> but not that only this single ponor feeds only this particular
> spring, as there can be other ponors feeding this spring, and other
> springs fed by this ponor.

Which is why mapping this is not really within the scope of OSM - 
natural underground waterflows are inherently non-verifiable.  

You can and should map the surface phenomena related to the underground 
water flow of course - ponors, dolines, karst springs and other stuff.

-- 
Christoph Hormann
http://www.imagico.de/

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