Better Definition of natural=beach

tekim · 2024-05-20T23:05:11.025Z

With the recent Pokemon-related addition of natural=beach features to OSM I feel the project could benefit from a more specific definition of this feature. Some mappers are pushing the limit of what I would consider a “beach”, which sometimes seems to include almost any bit of ground next to almost any waterbody. I offer the following as a starting point for the discussion. This is only intended to be a starting point.

Must be immediately adjacent to water (natural=water/coastline), there can be no intervening non-beach area or structure that would impede water ingress or egress.
Beaches are generally formed naturally by wave, tide, and current action.
Generally only found next to large bodies of water, such as natural=coastline and natural=water + water=lake
Generally not found next to ponds and small lakes
Surface must be loose (e.g. sand, pebbles, shells). If one kicks the surface of a beach many small particles should become airborne (provided the surface is not water-saturated). The surface is easily moved with a hand shovel.
Surface must not be mud, silt, bare rock, grass
Any vegetation must be sparse and discontinuous as vegetation will tend to anchor an otherwise loose surface as well as impede the wave and current action that is essential for the generation of beaches.
If the surface area is composed of a significant number of rocks larger than ~8 cm (~3 inches) it is not a beach.
Beaches generally slope gradually, and uniformly, down towards the water.
The exposure of ground by low tide, low water levels in a large river, or low water in a reservoir by itself does not qualify as a beach.
Generally some portion of a beach should be exposed at mean high tide or maximum water level in a reservoir.
Sandbars in rivers are generally not beaches (not sure about this one, but I am seeing such things mapped as beaches)
Beaches are not found next to swimming pools or fountains (unless they are also immediately adjacent to a natural waterbody)
Beaches can be manmade if they mimic the above characteristics.
It is best to map beaches as areas, but nodes are acceptable.

Minh_Nguyen · 2024-05-21T00:18:46.207Z

There’s enough specificity here that one might have to play Pokémon Go! in order to determine whether a nearby spit of sand is really a beach. But I get the gist; it’s close to my mental model of a beach too. No wonder: as speakers of the language that has the word “beach”, you and I can simply rely on intuition, whereas speakers of some other languages may not be so lucky, because English derived this word from an ancient word for waterways.^[1]

We’d have to decide which of these rules are canonical and which are merely rules of thumb when in doubt. Is a beach defined by its character and composition or by geomorphology, by measurements or by, uh, kicking?

In Vietnamese, a very unrelated language, the common translation for “beach”, bãi biển, means “flat open space by the sea” but is understood to be made of fine white sand. In the mind of a Vietnamese speaker, a lawn by the sea would be a bãi cỏ, emphasizing the grass instead of the sea. ↩︎

Kai_Johnson · 2024-05-21T02:59:19.336Z

I think most of what you’re saying makes sense.

Where did you get the cutoff of ~8 cm for the size of stones on a beach?

There are definitely beaches along rivers, typically not sandbars in the middle, but certainly along the shores.

Friendly_Ghost · 2024-05-21T03:08:10.150Z

tekim:

Beaches are generally formed naturally by wave, tide, and current action.

As a Dutch person I object to this. See Relation: 6768273 | OpenStreetMap

tekim:

Surface must not be mud, silt, bare rock, grass

My local beach along the Rhine is partially overgrown with grass. It’s somewhat impressive that the grass survives on sand.

tekim:

Sandbars in rivers are generally not beaches (not sure about this one, but I am seeing such things mapped as beaches)

I’d tag those as natural=sand.

It’s a very good write-up. I’m sure that we can use it to tag beaches and places that do not classify as beaches more consistently.

osmuser63783 · 2024-05-21T07:09:47.295Z

I found the following articles helpful when reading about beach mapping:

Reefs and beaches in the OpenStreetMap standard style
Coastal geography for mappers in OpenStreetMap

About your list…

Chesil beach would fail the kick test, and so would many shingle beaches, does that mean they are not beaches?
“Generally some portion of a beach should be exposed at mean high tide”, again this excludes some beaches, why this rule? Counterexample

Mammi71 · 2024-05-21T07:59:53.947Z

osmuser63783:

“Generally some portion of a beach should be exposed at mean high tide”, again this excludes some beaches, why this rule? Counterexample

What in this counterexample would contradict this rule?

Mammi71 · 2024-05-21T08:03:02.345Z

Friendly_Ghost:

As a Dutch person I object to this. See Relation: 6768273 | OpenStreetMap

That’s not a contradiction, @tekim already wrote:

tekim:

Beaches can be manmade if they mimic the above characteristics.

osmuser63783 · 2024-05-21T08:08:57.045Z

One feature, Six mappers and still More ways to map it:

What in this counterexample would contradict this rule?

The beach in the photo at the top is completely under water at high tide.

Duja · 2024-05-21T08:49:09.653Z

From Skunked tags:

A skunked term is one whose meaning has evolved over time, making it difficult for a reader to know what was originally meant and making it difficult for a writer to use without causing confusion or offense. Likewise, a skunked tag is one that has been redefined over time, making it difficult for a data consumer to know whether a given occurrence of the tag was meant to follow the old or new definition.

“beach” is a textbook example of one: while most dictionaries provide definition along the way of “sandy or pebbly strip adjoining the water” (1), the related, commonly understood meaning (2) is “place on the shore where people go bathing and sunbathing”.

Now, (1) and (2) frequently coincide, so there is no problem. But then, places like Namibia or Mauritania have thousands of kilometers of natural sandy beaches (1) devoid of humans; and all over the world people go sunbathing and bathing on concrete, grassy, stone, or artificial surfaces, commonly called “beach” in sense (2). Granted, we have sense (2) encoded in leisure=bathing_place, leisure=swimming_area, and/or leisure=beach_resort but none of those encompasses the whole range of simple term “beach”.

If you ask me, I would get rid of the skunked tag natural=beach and replace it with natural=sand/shingle/bare_rock/... as appropriate, and rename leisure=bathing_place (which covers most scope of meaning (2) ) as leisure=beach. But that is admittedly too ambitious…

Mammi71 · 2024-05-21T08:51:34.617Z

“generally” does not mean absolutely “always”.

If steep rocks limit the spread of the beach towards the land, then that’s just the way it is.

alan_gr · 2024-05-21T09:11:45.407Z

Duja:

“beach” is a textbook example of one: while most dictionaries provide definition along the way of “sandy or pebbly strip adjoining the water” (1), the related, commonly understood meaning (2) is “place on the shore where people go bathing and sunbathing”.

Are you saying this is a problem in English, or in the way the English words are interpreted in other languages?

I can’t speak for the whole English-speaking world, but In Ireland I don’t see a particular issue here. As far as I can see natural=beach is consistently used for sandy/pebbly strips, and the leisure tags for known bathing places that are not sandy/pebbly strips. For example, these two neighbouring spots, both popular for bathing:
Sandycove Beach, a small stretch of sand tagged as natural=beach: Way: ‪Sandycove Beach‬ (‪35356861‬) | OpenStreetMap
Forty Foot Bathing Place, a combination of rocks and artificial stone, tagged as leisure=bathing_place: Node: ‪Forty Foot‬ (‪332211029‬) | OpenStreetMap

Here the OSM tagging seems to match the way people normally refer to these places. Whereas under your alternative suggestion we would have the counterintuitive situation of removing the beach tag from the spot everyone calls Sandycove Beach, and adding a beach tag to the 40 Foot Bathing Place, which nobody calls a beach.

Mateusz_Konieczny · 2024-05-21T12:53:34.834Z

Duja:

“beach” is a textbook example of one: while most dictionaries provide definition along the way of “sandy or pebbly strip adjoining the water” (1), the related, commonly understood meaning (2) is “place on the shore where people go bathing and sunbathing”.

Now, (1) and (2) frequently coincide, so there is no problem. But then, places like Namibia or Mauritania have thousands of kilometers of natural sandy beaches (1) devoid of humans; and all over the world people go sunbathing and bathing on concrete, grassy, stone, or artificial surfaces, commonly called “beach” in sense (2). Granted, we have sense (2) encoded in leisure=bathing_place, leisure=swimming_area, and/or leisure=beach_resort but none of those encompasses the whole range of simple term “beach”.

If you ask me, I would get rid of the skunked tag natural=beach and replace it with natural=sand/shingle/bare_rock/... as appropriate, and rename leisure=bathing_place (which covers most scope of meaning (2) ) as leisure=beach. But that is admittedly too ambitious…

In which direction you think things went wrong? Using natural=beach for (1) where (2) does not apply?

In such case I see no skunking taking place. Yes, Namibia has a lot of beaches not used for leisure. These are still beaches.

Duja · 2024-05-21T15:59:00.380Z

alan_gr:

Are you saying this is a problem in English, or in the way the English words are interpreted in other languages?

Mateusz_Konieczny:

In such case I see no skunking taking place. Yes, Namibia has a lot of beaches not used for leisure. These are still beaches.

Alright, I withdraw that. Having done some homework, “beach” has been mainly used in meaning (1) both in real world and, as natural=beach, in OSM. While man-made shores like this may be called “beach” in real life… :

commons.wikimedia.org

File:Clovelly dusk.jpeg

(Clovelly Beach, Sydney)

commons.wikimedia.org

File:Old Digha Beach Concrete shoreline at Sunrise (solarised).jpg

commons.wikimedia.org

File:Narrow-Gauge-Railway Dalmatinerbahn Herceg-Novi (3).jpg

(Topla beach, Herceg Novi)

…we have an appropriate leisure=bathing_place for things like that.

ezekielf · 2024-06-10T03:29:34.074Z

I just noticed that OSM Wiki - Key:tidal was modified a couple of years ago, adding this statement:

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

This doesn’t strike me as a consensus view. If more beach is exposed at low tide it seems perfectly reasonable to tag it as natural=beach. Sometimes what is exposed at low tide is no longer a beach (mudflat, etc) and in that case it should be tagged as something else, but saying that natural=beach is only ever for the above high tide part of the beach seems silly. Should this text on the wiki be changed?

Minh_Nguyen · 2024-06-10T05:09:12.260Z

This same edit reaffirmed that the coastline would be mapped at the high water mark. It says no beach can intrude on a body of water, but the tidal area can be either a natural=wetland wetland=mudflat or natural=sand.

This is somewhat counterintuitive to me. All up and down the California coast, you can find beaches that are popular attractions at low tide and completely submerged at high tide. At high tide, there is no space between the water line and the coastal cliff. Yet no one here would deny the existence of beaches along the coast and describe them as mere deposits of sand.

commons.wikimedia.org

File:The Ritz-Carlton, Half Moon Bay, CA USA (San Matteo Coast) - panoramio (5).jpg

osmuser63783 · 2024-06-10T05:10:22.223Z

This also came up here, where @Taya_S proposed a similar change:

Intertidal tagging inconsistencies: beach, sand or tidalflat Tagging general discussion

Howdy. 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 natural=wetland [mix of natural=sand, natural=wetland and natural=wetl…

ezekielf · 2024-06-12T19:09:48.719Z

I’ve updated the tidal wiki page with what I believe is a more nuance and accurate description of natural=beach usage in relation to natural=coastline: Key:tidal: Difference between revisions - OpenStreetMap Wiki

02JanDal · 2024-06-14T05:49:13.772Z

Duja:

If you ask me, I would get rid of the skunked tag natural=beach and replace it with natural=sand/shingle/bare_rock/... as appropriate, and rename leisure=bathing_place (which covers most scope of meaning (2) ) as leisure=beach. But that is admittedly too ambitious…

Some (potentially relevant) previous discussion: Clarification on the mapping of bathing places

(personally I think it makes sense to separate the natural feature (natural=beach, though I’d be, on principle, alright with natural=sand/etc. as well) and what humans make of it (leisure=*), it’s after all easy to double tag and as was discussed in the above topic the second meaning helps differentiate between “could you use it as a beach” (might be awesome looking sand and water, but unknown to you there are dangerous currents) and “should you use it as a beach”)

Minh_Nguyen · 2024-06-14T06:35:17.621Z

I would not assume that a beach is inherently a swimming or bathing facility. Here along the Northern California coast, I know many who enjoy taking long walks on the beach. They can’t or wouldn’t swim in the frigid Pacific waters, but they “use” the beach more than the surfers do.

trigpoint · 2024-06-14T07:24:44.152Z

I would agree with this statement.

People go to beaches to walk, have a barbecue or just sit and watch the sunset.

Occasionally they may go for a drive!

DSC_02511920×1440 148 KB

DSC_02731920×2560 326 KB

DSC_02741920×2560 280 KB