[Tagging] Watershed or Drainage Basin relation draft proposal

Martin Koppenhoefer dieterdreist at gmail.com
Thu Sep 13 14:01:41 UTC 2018



sent from a phone

> On 13. Sep 2018, at 10:02, Joseph Eisenberg <joseph.eisenberg at gmail.com> wrote:
> 
> "do we really have to map this explicitly with relations? Can’t you already see them from the waterway and ridge data?"
> 
> 1) Ridges are missing in many parts of the world, partially because they are not rendered, but also because it might not be clear how they can be useful. The presence of watershed relations, mapped along ridges, would encourage other mappers to add the missing ridges. 


you’ll have to put the ridges to map the watersheds anyway, the catchment basin is implicit with the waterways, coastlines and ridges. 

If there are names or other properties for the watersheds and catchment basins in play, it could make sense to have dedicated objects nonetheless, I agree.



> 
> 2), while a ridge has to have a certain amount of slope to be called a ridge (perhaps at least 5 or 10% grade?), watershed boundaries are sometimes very shallow


how can we observe those sheds in shallow areas? Can it be done on the ground or does it require additional elevation data? Maybe in the context of shallow land the sheds aren’t stable?


WRT imports, if license is suitable and resolution satisfactory I would not generally oppose the idea of an import.


Cheers,
Martin 




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