[OSM-talk] Mapping rivers that flow into/through lakes?

Fran├žois Lacombe fl.infosreseaux at gmail.com
Fri Feb 23 10:58:52 UTC 2018

 (Sorry Rory, resent this to Talk ML)

2018-02-23 11:35 GMT+01:00 Rory McCann <rory at technomancy.org>:

> On 23/02/18 06:53, Maarten Deen wrote:
>> I see nothing wrong with those examples, I would do it the same,
>> especially if the rivers can be sailed on by boat. Then you absolutely need
>> the rivers to be connected to a central river (or fairway) in the lake.
> But then how far do you go? Should every stream be connected to the
> central river? e.g. what about here ( http://tools.geofabrik.de/osmi
> /?view=water&lon=28.57869&lat=-16.75136&zoom=11 )?

Yes: http://tools.geofabrik.de/osmi/?view=water&lon=28.57869&

> If some rivers/streams shouldn't be connected, then some data consumers
> will have to do an automatic connection anyway. When measuring water run
> off and pollution, you probably want to know that "stuff going into
> stream X will eventually get to point Y downstream" (right?).

I don't get this, which situation do you think of when you say " If some
rivers/streams shouldn't be connected " ?

> Connecting all means that large lakes will be full of a "skeleton" of
> joining rivers/streams, and a small 1km stream could get a lot longer.

Yes they do http://tools.geofabrik.de/osmi/?view=water&lon=28.57869&

This can be solved by removing waterways sections which intersect with
lakes water body.
It could be done on consumer purpose for a particular usage.
Topology is also a really useful data and waterways should definetly
connect downstream sections.

2018-02-23 11:45 GMT+01:00 Joseph Reeves <iknowjoseph at gmail.com>:

> Slightly off topic, but I was recently wondering if there was a waterway
> routing tool available? As in, I'd like to click a point in a waterway and
> have the downstream route plotted, presumably to the sea. It appears to me
> that a tool like that could be useful in this discussion?

You can achieve this with OSRM with a proper routing profile, or even
pg-routing if you are at ease with it.

All the best

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