[HOT] Waterway Tags

Blake Girardot bgirardot at gmail.com
Thu Jan 22 00:18:52 UTC 2015

I think water and waterways are some of the most difficult to map and 
tag features there are, even when things are simple and clear in imagery.

To Ralph's points:

As to the tagging suggestion, Ralph, I _think_ the current best practice 
is to tag an intermittent stream or river like this:

waterway=river (or stream)

If we get the map rendering (rendering basically means "drawing" the 
map, turning the data tags into a graphic map we are used to looking at) 
correct based on those tags, would that fit with what you had in mind 
for the new tags you suggested?

As to how those features are "drawn" so they make sense when you look at 
the printed or rendered map, that is up to whatever source generates the 
rendering of the OSM data tags we put on the water features.

For example, the main OSM rendering "look" is handled by a style sheet 
(CartoCSS) called "openstreetmap-carto" which is kept in github and you 
can open issues there to ask them to alter it (in addition to talking 
about it here of course, but to really get them to change it will have 
to be brought up there as a github issue eventually)

And you can see how they render the water stuff in the water.mss file


But there is also the "Humanitarian Layer" which renders things 
differently, both what tags it renders and how it "draws" them.

And that rendering in controlled by HOT's very own CartoCSS style sheet:

And you can see how they "draw" water features in the main.mss file.

(now that I look at it, I see they only render differences if the 
waterway has seasonal=yes on it, which I never use but I guess I need to 
rethink that :)

ybon and skorasaurus here or in IRC are the two people most involved 
with the the HOT HDM (Humanitarian Data Model) CartoCSS style sheet and 
will be good people to hear from about changes to how the map data is 

Does any of that help?


On 1/22/2015 12:18 AM, john whelan wrote:
> I have difficulties with water I must confess.  I'm mapping from a
> satellite image taken an a particular day.  All I see is water, not wadi
> etc.  If its a River I'm supposed to note which direction it flows.  My
> eyesight isn't that good.  A wide river isn't a problem but when is a
> Stream a River or the other way round, or sometimes I see a series of
> elongated patches of water and I'm unclear what those are.
> Unfortunately I think we need people on the ground to better tag what we
> are doing from the satellite image.
> Cheerio John
> On 21 January 2015 at 18:04, AYTOUN RALPH <ralph.aytoun at ntlworld.com
> <mailto:ralph.aytoun at ntlworld.com>> wrote:
>     I would like to raise the issue of tags for /waterway=river/,
>     /waterway=stream/ and/waterway=wadi./
>     The problem that exists with the existing tags is that there is no
>     visual difference on the map for a stream (perennial) and a stream
>     (intermittent) and the only other option is wadi which gives a blue
>     pecked line.
>     Accepted mapping standards for this would be to show:-
>       all perennial rivers and streams as a continuous solid blue line
>     (indicating that there is flowing water all year round)
>       all non-perennial rivers and streams as a continuous blue pecked
>     line (indicating that there is flowing water during the wet season
>     but not the whole year).
>     A wadi would be depicted with a continuous pecked brown line
>     (indicating that it is dry watercourse and could be dry for years at
>     a time...only flowing if there is a flash flood or unusually heavy
>     rain).
>     This would then convey the correct meanings with symbols on the map
>     and make reading the map a lot easier. The categories would still be
>     searchable and distinguish between the three categories of water flow.
>     The proposed tags would then be
>     /waterway=river/ ...... /waterway= stream/ ...... continuous solid
>     blue line
>     /waterway=river_intermittent ...... waterway=stream_intermittent
>     ..... /continuous pecked blue line
>     /waterway=wadi/ .....continuous pecked brown line (a wadi can be so
>     wide that another tag would be needed similar to the tag for river
>     banks) /waterway=wadi_bank/ which would still be a brown pecked line.
>     This would then ease the path for introducing the tags for perennial
>     lakes with a solid blue outline and lighter blue fill, intermittent
>     lakes with a blue pecked outline and a light blue fill and dry pans
>     with a brown pecked outline with a brown stipple fill.
>     I can figure out a single tag proposal on wiki but do not know how
>     to do this more complex proposal as it entails changing all the tags
>     at the same time along with their map symbols.
>     If it is deemed appropriate is there someone who could do this?
>     Reference......
>     http://pubs.usgs.gov/gip/TopographicMapSymbols/topomapsymbols.pdf
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