> there is natural=bare_rock for some cases, generally I would go with 
> landcover tags. Knowing the composition of the material would be interesting 
> to understand what to expect when it is wet.

natural=bare_rock<https://wiki.openstreetmap.org/wiki/Tag:natural%3Dbare_rock> 
is about bedrock, not related at all with ground. 
landcover=*<https://wiki.openstreetmap.org/wiki/Proposed_features/landcover> 
would fit for this purpose, but it is a proposal as well and the wikipage has 
been updated since long time. Furthermore I believe landcover=* would be a 
duplication of already existing tags (eg. natural=wood and landcover=trees).

> We have established and usually quite consistently used tags for a number of 
> fairly specific natural or semi-natural non-vegetated surfaces - 
> natural=bare_rock, natural=scree, natural=shingle, natural=sand and 
> natural=mud and more specifically in coastal environments natural=beach, 
> natural=shoal, natural=reef and natural=wetland + wetland=tidalflat.  It 
> would therefore be rather counterproductive to introduce a new umbrella tag 
> engrossing those like natural=bare_ground.

It seems to me that up to now there is a duality of tagging in OSM for 
landcover: basically there are some tags that refer to 'what's on the imagery' 
(eg. natural=sand, natural=rock ...) and others which focus on the geological 
meaning of the feature (natural=shingle, natural=scree ...). By the way it 
seems to me very strange that there is nothing there for a straightforward 
feature as ground: compacted soil with very few or no vegetation, which can be 
of mineral or organic nature. This, as I told you, would be super useful for 
off-road navigation (to know if your car/motorbike/tank will get stuck into the 
mud).

I agree by the way that dried lakes are mostly mapped with natural=wetland + 
intermittent=yes, which makes sense and again refers to the role that natural 
feature is playing in the environment. But a tag on ground will possibly cover 
all the other cases, as I find it's a huge gap in landcover tagging.

>The local, regional, or global Copernicus time series datasets are 
>specifically meant to overcome this. 
>https://land.copernicus.eu/global/products/
"The Water Bodies product detects the areas covered by inland water along the 
year providing the maximum and the minimum extent of the water surface as well 
as the seasonal dynamics. The area of water bodies is identified as an 
Essential Climate Variable (ECV) by the Global Climate Observing System (GCOS)."
The global ones are built of higher resolution datasets with variable 
accessibility. Like the JRC’s Global Surface Water (MWE-GSW) Dataset at  
https://global-surface-water.appspot.com/map ... "...location and temporal 
distribution of water surfaces at the global scale over the past 3.6 decades, 
and provides statistics on their extent and change ..."

Open global coverage dataset can definetely help to map landcover and many ones 
are out there. The discussion is not about seasonality of lakes but generally 
on ground.

To me, a tag proposal natural=ground, ground:type=organic/mineral with the 
further possibility to specify soil type seems reasonable.

Thanks,

--
Michael Montani
GIS Consultant, Client Solutions Delivery Section
Service for Geospatial Information and Telecommunications Technologies
United Nations Global Service Centre
United Nations Department of Operational Support

Brindisi | Phone: +39 0831 056985 | Mobile: +39 3297193455 | Intermission: 158 
6985
E-mail: michael.mont...@un.org<mailto:m...@un.org> | 
www.ungsc.org<http://www.ungsc.org>

[cid:aecd50ec-b315-4265-bf62-424fec50adeb]
________________________________
Da: Michael Patrick <geodes...@gmail.com>
Inviato: domenica 5 luglio 2020 22:01
A: tagging@openstreetmap.org <tagging@openstreetmap.org>
Oggetto: Re: [Tagging] Are we mapping ground on OSM?


> Generally mapping bare ground beyond the specific established tags mentioned 
> earlier is often hard without local knowledge.  Imagery taken during dry 
> season will often read like bare ground while there is often fairly extensive 
> plant growth (like natural=grassland) that dries up and looks 
> indistinguishable from bare ground even on high resolution imagery.

The local, regional, or global Copernicus time series datasets are specifically 
meant to overcome this. https://land.copernicus.eu/global/products/

"The Water Bodies product detects the areas covered by inland water along the 
year providing the maximum and the minimum extent of the water surface as well 
as the seasonal dynamics. The area of water bodies is identified as an 
Essential Climate Variable (ECV) by the Global Climate Observing System (GCOS)."

The global ones are built of higher resolution datasets with variable 
accessibility. Like the JRC’s Global Surface Water (MWE-GSW) Dataset at  
https://global-surface-water.appspot.com/map ... "...location and temporal 
distribution of water surfaces at the global scale over the past 3.6 decades, 
and provides statistics on their extent and change ..."

I did a cursory look-see at several places in the Western U.S. Basin and Range 
region using only the ROI preview capability in the portal , especially Sevier 
Lake in Utah ( most of these 'lakes' tend to be of a single type, though ) . In 
combination with other Copernicus and NASA datasets one can get a fair idea 
what's going on.

Your mileage may vary.

Michael Patrick


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