[Tagging] Tidal inlets / creeks

Ulf Mehlig ulf.mehlig at gmx.net
Wed Jan 19 15:11:17 GMT 2011

As has been said before, it does not make too much sense to map the
coastline along the mean high water level in mangrove areas and
(probably) salt marshes, which +-always are below the HMWL. Here in
north Brazil, I just map the non-vegetated, flooded areas as sea, having
mangroves, beaches and marshland on the landward side of the coastline
(using multipolygons tagged as "natural=wetland, wetland=mangrove",
which integrate coastline segments as outer borders). PGS data shows, by
the way, mangroves as "sea" in many areas around here (not everywhere,
depending probably on the remote sensing technique applied).

A benefit of having a specific tidal channel type (linear way) would be
the possibility to name the channels (and maybe also to attach
information as viability for certain types of vessels).

Regards, Ulf

On Tue, 2011-01-18 at 15:53 +0000, Malcolm Herring wrote:
> On 18/01/2011 12:44, charlie at cferrero.net wrote:
> >
> > It would be nice to be able to map the tidal waterways that run in
> > between the mangroves and saltmarshes - particularly the manmade ones
> > that have been explicitly cleared to allow marine vessels. Unfortunately
> > I can't see any way of tagging a waterway that does not imply
> > freshwater. Ideally we'd have a waterway=tidal_creek or something like
> > that but this doesn't seem to be in use at all.
> >
> A way tagged natural=coastline should follow the local mean *high* water 
> level so that all tidal areas will be on the wet side of the way. Any 
> tidal areas (wetlands of all types, beaches, mud, etc) can be mapped as 
> closed polygon ways that enclose areas above the local mean *low* water 
> level. These areas will be rendered at the higher zoom levels. Navigable 
> channels that exist between these areas will then have been left as 
> non-tidal (i.e. always wet)
> >
> > Finally, is there a way of tagging saltwater lakes (i.e. lagoons)?
> > natural=water, water=saltwater?
> >
> If the lagoon has a channel to the sea, then simply extend the coastline 
> into them. If they are completely cut off, then your suggestion would be 
> OK.
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 Ulf Mehlig <ulf.mehlig at gmx.net>

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