[Tagging] Overlapping lakes

Christoph Hormann osm at imagico.de
Sat Feb 13 11:03:05 UTC 2021


On Friday 12 February 2021, Richard Fairhurst wrote:
>
> Duplicating the geometries like this seems wrong to me.

It is definitely not widely used mapping practice to do so.

That geographic features have names assigned on different levels is 
pretty normal.  However when we map water areas with natural=water that 
is primarily mapping of the physical geography and not of the local 
conventions of naming.  A good example is Lake Balkhash, which has a 
freshwater part and a saline part which are mapped as two separate 
natural=water areas:

https://www.openstreetmap.org/relation/35904
https://www.openstreetmap.org/relation/3367363

each with the appropriate tagging to characterize it physically.  It 
would be incorrect to add another natural=water polygon covering both 
because that would either incorrectly characterize the saline part or 
the freshwater part.

We have lots of other cases where mappers have chosen to split standing 
water areas based on either cultural, physical or geometric divisions 
or just for convenience of mapping:

https://www.openstreetmap.org/relation/930549
https://www.openstreetmap.org/relation/930549
https://www.openstreetmap.org/relation/2322979
https://www.openstreetmap.org/relation/2101875
https://www.openstreetmap.org/relation/7708045
https://www.openstreetmap.org/relation/8420431

The only case similar to the one you mentioned i know is

https://www.openstreetmap.org/relation/1410914
https://www.openstreetmap.org/relation/7336746

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



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