Mapping / maintaining 'natural' coastlines in OSM

[SekeRob]

The wiki is sparse, the www is too. When viewing local coastline mapping, some seem imported, some hand drawn, it is noted the ‘natural’ coastline is also drawn around groynes, piers, breakwaters… man made elements extending into the sea attached directly to land, rendering in Carto S without the need of there actually needing to be coastline included. Question is: Do we or do we not keep the coastline where the coastline ‘naturally’ is/was? for these fingers sticking out into the sea?

The below had 3 mapped with the coastline going around. The longest, a bit further south east did/does not exist upon surveying called for after seeing the SE coastline adapted but not showing in any aerials and thusly removed it from the coastline profile. Found there was a smaller one more NW, all 3 signed as prohibited for entry by the public, chain fenced to boot. All having a nice sleek appearance indicated fairly recent construction. That newest one I did for now not move the sea boundary around pending this question.

Looking around found e.g. a Dutch coastline section excluding them, in fact the coastline is kept back from where the man made’s are, way up the beach.

[Taya_S (Taya Snijder)]

@SekeRob

Question is: Do we or do we not keep the coastline where the coastline ‘naturally’ is/was? for these fingers sticking out into the sea?

I’d argue that both are alright and that it is just a matter of how much detail you want to add. I’d also like to point out that groynes and breakwaters can be added as linear ways, making it impossible to draw the coastline around them.

@SekeRob

‘naturally’ is/was?

I know you already put ‘natural’ in quotes, but I really don’t like this term. There is no requirement for the coastline to be where it naturally should be. Otherwise we’d need to overhaul a whole lot of sea harbours.

@SekeRob

Looking around found e.g. a Dutch coastline section excluding them, in fact the coastline is kept back from where the man made’s are, way up the beach.

This groyne is outside the MHWL and looks tidal to me. (Admittedly, it is rather hard to be sure based on just this picture.) Based on that I don’t think it should be inside the coastline regardless of this discussion.

[SekeRob]

OK, so for local consistency, I’ll map that new one with the coastline going around, not tidal, stays dry unless a storm breaks loose. Had checked other places and facility grounds/docks are worldwide ‘inside’ i.e. left of the drawn demarcation line.