[Tagging] Tagging mangroves over water?

Warin 61sundowner at gmail.com
Sat Dec 29 20:51:42 UTC 2018

On 29/12/18 22:52, Christoph Hormann wrote:
> On Saturday 29 December 2018, Joseph Eisenberg wrote:
>> Have you seen any areas of mangroves tagged over water? That is,
>> outside of the coastline or over natural=water or waterway=riverbank
>> areas?
>> [...]
> I think this discussion has already been made in the past.  The majority
> of mangroves that are mapped are mapped inside the coastline (on
> land) - primarily because the outer edge of the mangroves is well
> verifiable while the high water mark on ground level inside the
> mangroves is not.  Formally it would depend on if you consider the high
> water mark to refer to ground level or canopy level.

I think that is a mistake.

OSM tries to map the high water level, to me that is where the water is at high tide, without consideration of vegetation.
In a mangrove system the high water mark is closest to the land side of the mangroves - not the water side of the mangroves.

I'd think at least 80% of the mangroves are within the high water mark.

>> I would like to be able to render mangroves with a fill color, as
>> with wetland-swamp, a similar environment. But this will case a large
>> change in the appearance of the coastline if many areas have been
>> tagged outside of the coastline, over the water.
> Rendering mangroves with a fill color has already been discussed in:
> https://github.com/gravitystorm/openstreetmap-carto/pull/1497
> https://github.com/gravitystorm/openstreetmap-carto/issues/2025

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