[OSM-talk] Mapping rivers that flow into/through lakes?
Maarten Deen
mdeen at xs4all.nl
Fri Feb 23 11:04:01 UTC 2018
On 2018-02-23 11:35, Rory McCann wrote:
> 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
> )?
Mappers discretion. I'm not advocating a "must" in this case. I'm saying
it's not a bad thing if it is done and in some circumstances it is
preferrable.
See it as roads connecting to a square. As long as routing over areas is
not commonplace it is acceptable and even preferrable to lay roads over
the square.
> 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?).
Yes. OSM gets used (maybe misused) for all kinds of purposes, but a
hydrological analysis would be impossible if streams that are physically
connected are not so in OSM.
> 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.
Good point, but can be solved by using relations for the streams and not
including the part of the stream that runs through the lake. In any
case, I would think it strange to still use the the name of the stream
on the part that runs through the lake.
Maarten
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