I’ve been mapping a lot of tidal areas over the past year. Mainly estuaries with large tidalflats and saltmarshes.
One of the things I have noticed while doing so is that the tagging schemes for the intertidal areas are a bit of a mess.
There are 3 main ways intertidal areas are being tagged currently
natural=beach + tidal=yes
natural=sand + tidal=yes
natural=wetland + wetland=tidalflat
and sometimes also just
The wiki pages don’t seem to agree on how to tag the intertidal parts of beaches:
The beach wiki page says to use
natural=beach for ‘inclined, wave formed areas at the coast’. And for larger flat areas use either
The tidal key wiki says “Don’t use natural=beach for an area under water at high tide, the value beach is only for the part above the coast line”
Both agree that
wetland=tidalflat is only for flat muddy areas.
But this is not how these areas are being mapped currently. At the moment
wetland=tidalflat are the two most popular tagging scheme’s I come across.
With Germany, Denmark, the Netherlands and Belgium basically exclusively using
while France uses
wetland=tidalflat in the north, but then switches to a mix of
natural=sand further south.
and in the UK its all over the place. OpenStreetMap Over here you can find all three options next to each other.
How I think it should be tagged:
I believe that having
natural=beach for smaller ‘inclined, wave formed areas at the coast’ makes sense. I’m unsure whether
tidal=yes is strictly necessary, considering that the coastline already makes it clear where the Mean high water line is.
For larger flat intertidal areas I believe
natural=wetland + wetland=tidalflat + surface=* would be a better solution than having both sand and tidalflat.
The only differentiating factor between
wetland=tidalflat is whether the surface is muddy or sandy. This is pretty vague and open to interpretation in my opinion. Plus we already have a handy
surface=* key for that. Then there is also the fact that multiple countries already exclusively use
wetland=tidalflat. And finally, the name “tidalflat” already implies a function, a tag for flat intertidal areas.
I would like to hear other peoples opinions on this.
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Ce sujet de discussion accompagne la publication sur https://community.openstreetmap.org/t/intertidal-tagging-inconsistencies-beach-sand-or-tidalflat/104919