Stream to river transition

As part of the disaster preparedness mapping of the Nevado del Ruiz volcano, we are mapping many waterways from the source to the end. Most are streams (quebradas), and some rivers (ríos). However, they all begin very small (streams), and after merging with other streams, some become rivers.

Our doubt (@afgb1977 and me) is for the waterway and naming tagging. Let’s draw the stream with a dash and the river with an equal sign.

A) Should we change the waterway’s name (Gualí) according to its type?

--------------------====================>
    |                       |
    |                       |
  waterway="stream"         |
  name="Quebrada Gualí"     |
                            |
                            |
                          waterway="river"
                          name="Río Gualí"

b) Or should we call the whole course by its name? Even if the name does not match the type of waterway, at the beginning.

--------------------====================>
    |                       |
    |                       |
  waterway="stream"         |
  name="Río Gualí"          |
                            |
                            |
                          waterway="river"
                          name="Río Gualí"

c) I put the last option, but we think this is inappropriate, where the whole waterway has its file type and name, even if it does not match at all initially.

--------------------====================>
    |                       |
    |                       |
  waterway="river"          |
  name="Río Gualí"          |
                            |
                            |
                          waterway="river"
                          name="Río Gualí"

What should be the appropriate tagging for streams and rivers? I’ll appreciate your thoughts.

Usually a river is not originating from a single stream but from many different ones merging to form the river finally. From other places I know that in many cases the primary streams which lateron form a river do either not have any name at all, or have their own common names. In such cases I would tag accordingly, either no name tag for ther primary streams at all or use their own common names.

In case one of the primary streams is the major source of the later river I would use the official/common name of the river (Rio Guali in your example), unless there is another official/common name for the primary stream.

If there are other names in use by local people you could still add loc:name=*.

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NOTE: I am not familiar with Colombia specifically.

I would expect name to be actually used name which may not match feature type.

Note cases like Central City or Spišská Stará Ves (Ves means Village).

Note that Central City is village/hamlet named “City” with population of 93 (failed advertising attempt when this area was colonised), and Spišská Stará Ves (meaning translating to Old Spišská Village) is a town with population over 38 000.

If such name is used for the entire waterway then it is entirely fine.

Name as it is named - and use correct feature type representing what it is.

BTW, in case of city named “Beautiful River” it would be place=city not waterway=river (example fictional).
And name tag would be name=Beautiful River not Beautiful City

And in case of river named Long Forest (fictional example) it would be waterway=river not landuse=forest line.
And name tag would be carrying name=Long Forest.

That is definitely not OK (BTW, your image does not work here, you should have only =).

See say Czarna Wisełka – Wikipedia, wolna encyklopedia which is waterway=stream of Vistula - Wikipedia

Or Node: ‪Витік річки Західний Буг‬ (‪5087016797‬) | OpenStreetMap Źródło Bugu w Werchobużu - wycieczka krajoznawcza na Ukrainę - initially small part of Bug river.

I am pretty sure that there are rivers named “XXXXX Stream” and streams named “YYYYY River” but have no examples right now.

3 Likes

Short answer: b

Long answer

The best way to think of it is this: OpenStreetMap tags are for what they are, even if the name used is different.

In the case of waterways:

  1. it is very common for the source of a river to be waterway=“stream” before being waterway=“river”, even though everyone calls it Rio Nome-Do-Rio throughout its course. (This is your b)
  2. In rivers used for agriculture, the opposite can happen: the amount of water used is so large that it changes from a waterway=river to being a waterway=stream.
  3. Some rivers can also be used to artificially store water. And when is a mere water reservoir as in natural=water + water=reservoir (see Tag:water=reservoir) , the outlet (unless someone have better idea, this is what I’ve been doing) be waterway=stream + intermittent=yes (reason: the water will only pass through when the reservoir gets too full.
  4. Sometimes, some streams with the name of Steam Steam-Name have parts where it is visibly much larger, which could be a waterway=“river” (same as your b, just something names as steam instead of river).

Note: there are several other cases of water bodies, such as natural=wetland, wetland=swamp, (…), but here you might need more local knowledge than aerial images. However, even I would recommend always create some sort of line all the way, even if you have to pass over a dam or wetland.


Edit one: corrected (was objectively wrong, not mere point of view) the point 3 by Mateusz suggestion to explicitly exclude dam, and keep as use mere reservoir, which is more frequent in agriculture.

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I have seen waterway=canal usage=spillway intermittent=yes for things like https://www.youtube.com/watch?v=Uxte0WDbx9c (muting recommended) with capacity of 2000 m³/s (on this video only 450 m³/s of water is flowing).

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Good catch! The ones I’m mentioning (mostly used by agriculture) are like this one Way: 1150171047 | OpenStreetMap natural=water + water=reservoir. These are not used to generate electric energy, but just store water from very small steams.

Reviewing now, real dams use… waterway=dam like Way: ‪Represa de Palmar‬ (‪422157585‬) | OpenStreetMap. This one is not edited by me, but was tagged like tunnel=culvert + waterway=river.

I will edit my reply to change “dam” to water=reservoir

There is at least one prominent example where a well-known river maintains it’s name right from its source even though it starts out as a stream: the Thames. There’s also one local to me with a well-known source: I remember pondering exactly this issue when mapping it 14 years ago.

I therefore don’t think that there is one hard-and-fast rule, and to an extent this will depend on specific topography and, to an extent, on local tradition (apparently the true source of the Danube is disputed for reasons of local prestige)

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Would name=Gualí work?

I depends on what the real name of the river ist. Sometimes “Rio” or “River” is part of the name, sometimes it is not. We should tag the real name and not what could suite our tagging scheme best … :wink:

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