[Tagging] Feature Proposal - RFC - (Ground)

Michael Montani michael.montani at un.org
Mon Jul 13 07:29:24 UTC 2020

Doing some wrap up:

> Barren sounds to me to imply nothing can grow there.Bare sounds more
neutral and factual to me, it just says there is nothing but bare soil to
mark the area with.Please correct if I am wrong!

For the 'barren vs bare' discussion, I would go for natural=bare_soil, not only for the meaning but also for a matter of consistency with the already existing natural=bare_rock.

>Even those photos show that there is some vegetation there, even though
it's sparse.
At what level of plant growth, does it stop being "bare ground"? One
"plant" (tree / shrub / patch of grass etc) per sq km / 100 / 10 / 1 sq m?
Maybe, instead of saying it's bare ground, we need some way of describing
the level of ground cover eg vegetation=sparse or similar?

To me, I'm ok in considering bare_soil with some vegetation. But obviously not too much, otherwise I would switch to natural=scrub. Also, a natural=bare_soil + vegetation=sparse to me would be natural=scrub or natural=grassland. A (little) tree/shrub/patch every (approximately) 10 sq m or more seems good to me to state it's bare_soil. The photos I posted, have some scrub polygon surrounding the groundy area for sure.

Also, I would go for bare_soil targeting silt or clay soil, loam and mixture humus and mineral soil. To me, all these areas don't have a current OSM tag correctly defining all of them, apart when inserted in an environmental or geological context as wetlands.
Indeed, I wouldn't use bare_soil when a wetland can reasonably describe in a correct way the area, as well as a thin layer of grass (e.g. lichens in tundra) is covering the ground (in that case natural=grassland).
Furthermore to me is not meaningful to specify whether a soil is mostly humus as, if the organic matter percentage is high, most probably vegetation will grow there in a while. As you may have imagined, this tag proposal was born mostly to map arid areas rather than general soil, but soil seems to be a huge gap in OSM landcover tagging.

Unfortunately is very hard to retrieve on-the-ground photos in Africa, but I think these areas are very common in places outside the European context. Feel free to add photos (if you have any) at https://wiki.openstreetmap.org/wiki/Talk:Proposed_features/Ground#Examples


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

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Da: Joseph Eisenberg <joseph.eisenberg at gmail.com>
Inviato: domenica 12 luglio 2020 21:15
A: Tag discussion, strategy and related tools <tagging at openstreetmap.org>
Oggetto: Re: [Tagging] Feature Proposal - RFC - (Ground)

The link [2] to https://www.hq.nasa.gov/iwgsdi/Barren_Land.html has these categories: Bare Exposed Rock: Those ecosystems characterized by areas of bedrock exposure, desert pavement, scarps, talus, slides, volcanic material, rock glaciers, and other accumulations of rock without vegetative cover.

This is mostly covered by natural=bare_rock or natural=scree (or natural=shingle) currently. Beaches: Those ecosystems along shorelines characterized by smooth sloping accumulations of sand and gravel. The surface is stable inland, but the shoreward part is subject to erosion by wind and water and to deposition in protected areas.

This is natural=beach, or natural=wetland + wetland=tidalflat, or natural=shingle, possibly overlapping with water (if below the high tide line or high water line). Dry Salt Flats: Those ecosystems occurring on the flat-floored bottoms of interior desert basins that do not qualify as wetlands.

We don't have a good tag for this, as Christoph mentioned previously, probably because these features are rare in Europe. Mixed Barren Land: Those regions in which a mixture of barren land features occurs and the dominant land use occupies less than two-thirds of the area. This includes, for example, a desert region where combinations of salt flats, sandy areas, bare rock, surface extraction, and transitional activities could occur in close proximity.

We should map these areas based on the most specific area: natural=sand, natural=bare_rock, landuse=quarry, etc. Sandy Areas Other Than Beaches: Those ecosystems composed primarily of dunes -- accumulations of sand transported by wind. ...

This is usually mapped as natural=sand Strip Mines, Quaries, and Gravel Pits: Those regions where vegetative cover and overburden are removed to expose such deposits as coal, iron ore, limestone, and copper. This includes inactive, unreclaimed, and active strip mines, quarries, borrow pits, and gravel pits until other cover or use has been established.

Mapped as landuse=quarry Transitional Areas: Those regions that are in transition from one land use activity to another. This transitional phase occurs when, for example, forest lands are cleared for agriculture, wetlands are drained for development, or when any type of land use ceases as areas become temporarily bare as con- struction is planned for such future uses as residences, shopping centers, industrial sites, or subur- ban and rural residential subdivisions. This also includes land being altered by filling, such as occurs in spoil dumps or sanitary landfills. (Definition Source: A Land Use and Land Cover Classification System for Use with Remote Sensing Data)

This might be landuse=landfill, landuse=construction, or landuse=brownfield in many cases. Areas where trees have been recently cleared are somewhat debatable, if it's not certain what the area is transitioning into, but there is landuse=meadow + meadow=transitional for areas of grass that are transitioning into scrub or early woodland again.

So we certainly need a new tag for salt flats, and I agree that there are some places like badlands and deserts with clay soils where we don't have well established tags for unvegetated areas, but many types of "barren" land can already be mapped with existing tags. That's why it's important that new tags are precisely defined.

– Joseph Eisenberg

On Sun, Jul 12, 2020 at 10:37 AM mbranco2 <mbranco2 at gmail.com<mailto:mbranco2 at gmail.com>> wrote:
I hope that this discussion and the related proposal wiki page will lead to a solution, because I found several times, mapping in Africa with HOT projects, "desertic lands" and I didn't find a tag for this.

If we search the Internet for "barren soil", we can find a lot of ground-level related images.

And I think that we could map such characteristic even with only imagery (without direct survey), because it's a "macro" feature, as is a wood or a scrub.

Maybe images was shot in a particular season, and the soil condition is not always the same?
Well, if I check several imageries and in all of them I see a "desertic land", I'm confident I can map that area with the tag we're talking about. And I think it doesn't matter if for few days a year (or few days in several years...) it will rain and there will be - for few days - a bit of vegetation: it's not an OSM mapping rule, to map the "main" characteristic of an item?

Surely it could be useful if botanists and/or geologists could better specify (with more specific tags) the cause: no rain? pollution? specific ground-conditions such as presence of salt or sulfur?

For the main tag, I think that "natural" is the right key (being already natural=sand/bare_rock/shingle/scree...).
About the value, I'd prefer a botanic or geologist suggest us the best word.

Some references:
- "Barren vegetation" [1]  (..."Regions on the earth’s surface where soils are dominating the ecosystems with little to no plant cover are often referred to as “Barren”. )
- "Barren land" [2] (an old web page from NASA: "...ecosystems in which less than one third of the area has vegetation or other cover. In general, Barren Land has thin soil, sand, or rocks."). This web page cites "A Land Use and Land Cover Classification System for Use with Remote Sensor Data", a free paper you can find in Google Books too.
- "Barren soil is starving Africans" [3]

Other examples of "desertic" lands:
- Bonneville (USA) [4] (maybe some of you saw World's Fastest Indian, the lovely movie with Anthony Hopkins :-) )
- La Leona (Patagonia) [5]

Marco (mbranco2 / UNGSC-mbranco2)

[1] https://en.wikipedia.org/wiki/Barren_vegetation
[2] https://www.hq.nasa.gov/iwgsdi/Barren_Land.html
[3] https://www.nature.com/news/2006/060327/full/060327-15.html
[4] https://en.wikipedia.org/wiki/Bonneville_Salt_Flats
[5] https://visitpatagonia.com.ar/en/activities/petrified-forest-la-leona/

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