Proposed features/ephemeral

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"ephemeral"
Status: Abandoned (inactive)
Proposed by: Warin61
Tagging: ephemeral=no/yes/spring/summer/autumn/winter/dry_season/wet_season
Applies to: node, way, area, relation
Definition: Water presence is of short duration and seldom occurs.
Rendered as: vertical dashed blue
Drafted on: 2018-12-12

Proposal

Add the property key [W] ‘ephemeral’ to indicate the very short duration of water that occurs infrequently, with a threshold defined as having flow (even for part of a day) for less than 35 days per year and pools/lakes/wetlands holding water for less than 60 days per year. The majority of the time water is not present. These water features include streams, rivers, wetlands and lakes. Typically they are in or near desert areas.

The key intermittent=* is less specific in that it does not indicate this short duration, infrequency and lack of water for most of the time.

The key seasonal=* indicates a yearly characteristic that may not be present with ephemeral features, and a permanency during that season which is not the case with ephemeral.

If seasonal limits are present and known then values from the key seasonal=* may be used.

Definition

A property key for water features where the feature lacks surface water for the majority of the year, with a threshold defined as having flow (even for part of a day) for less than 35 days per year and pools holding water for less than 60 days per year. The majority of the time water is not present.

See the Determination Guide section below for how to determine if something is ephemeral.

Determination Guide

Determination of a water feature as ephemeral requires local knowledge. If it cannot be determined then do not add this tag.

Determination by Local Objective Data

Where the historical flow/presence of a water feature is ephemeral. This could be indicated by decades of local knowledge.

Where a water feature feeds resides in a climatic area of sporadic rainfall (example; no rain for years and then a few years rainfall all in one or two days) that would indicate that this water feature is ephemeral.

Determination by Proximity

Where a water feature feeds into another ephemeral water feature that would indicate that this water feature too is ephemeral.

Where a water feature is near an ephemeral water feature that is in the same climate that would indicate that this water feature too is ephemeral.

Rationale

Streams, rivers, wetlands and lakes in deserts maybe [W] ‘ephemeral’. There may be no flow for years, then a lot of rain all at once. There should be a way of tagging this characteristic.

Why not use intermittent or seasonal?

A 'desert map' should distinguish between intermittent, where water is more likely to be found even if you have to dig for it, and ephemeral, where water is very much less likely to be found. A typical ephemeral river with have deeper sections where water will pool, these could be mapped as water intermittent to distinguish them from rest of the ephemeral river.

Using the tag intermittent=ephemeral is similar to embassy=consulate, they are two similar but different things.

There is some confusion over what these keys mean, as an example to illustrate the differences;

Value Description
seasonal=winter Expect water to be here during all, or most of , winter.
intermittent=winter Water may be here in winter but not all the time. There may be more than one water presence during the season.
ephemeral=winter Water seldom here and only for a short duration and only in winter. It would be rare to have more than one water presence during the season.

Examples

See taginfo


Rivers

Way: Todd River (208044858) [W] Todd_River Todd River1.jpg |Todd River 31March88.jpg

Note the bridge viewable in the first photo gives some relativity to the water shown in the second photo.


Way: Tsauchab (380562360) [W] Tsauchab River

Wetlands

Relation: Goyder's Lagoon (9092118) [W] Goyders Lagoon

Lakes

Way: Lake Uloowaranie (223372106)

Relation: Lake Carnegie (1509128) [W] Lake Carnegie

Tagging

ephemeral=no/yes/spring/summer/autumn/winter/dry_season/wet_season

Value Description
ephemeral=no Indicates that a feature is not ephemeral. This is the default value and should not be required.
ephemeral=yes Water seldom be here and then only for a short duration.
ephemeral=spring/summer/autumn/winter/wet_season/dry_season/... describes exact season (if possible) when a feature is ephemeral.
Implies ephemeral=yes for that season. Note if uncertain as to the season use ephemeral=yes.

OSM uses British English, thus autumn not fall.
You could consider using a semi-colon value separator (;) to specify several seasons, but please note that very few applications actually support this.

(The above is paraphrased from the {[tag|seasonal}} page.)

Note that seasonal=dry_season is in use (even if by error or maybe it is in use on non-water features e.g. roads, some 2,900 uses of it), so it has not been excluded here as there might, just possibly, be one of them out in the real world.

Applies to

Water features.

May be used with;

Rendering

Proposed rendering for ephemeral water features: a vertical line of alternating blue dashes.


Features/Pages affected

Add as a possible property key to water features pages such as waterway=*, natural=wetland and natural=water. Add as a possible key to intermittent=*.

Tagging errors

If tagged seasonal=winter and ephemeral=winter then is the water present during winter most of the time (seasonal=winter suggest this) or is the water present only for short duration during winter (ephemeral=winter suggest this). This is a conflict of tags.

If tagged with both intermittent=yes and ephemeral=yes is a conflict as ephemeral is more restrictive than intermittent.

Default or addition of intermittent=yes

There is some suggestion that the key intermittent=yes should be manually added to all ephemeral entries. OSM says any tags you like, so this could be extended to any tag combinations you like.

In principle I see adding intermittent=yes as tagging for the render. Much the same as adding intermittent=yes to seasonal=* entries. So I paraphrase here what is on the seasonal page:

It is open question whatever it is preferable to tag (for example) river :

or

The view could be taken that data consumers are free to;

  • ignore any tags including intermittent, seasonal and/or ephemeral.
  • lump all of these tags together.
  • render some or all of these tags.

Present usage rates are;

Intermittent 3,710,000 Seasonal 322,000 Ephemeral 40,000

Voting on the key ephemeral

To come.

Previous Voting on the key ephemeral STOPPED DUE TO REMOVAL OF MATERIAL! Will restart after corrections

Start date was 17-7-2018, end date after 31-7-2018 (probably a fair way after).

Instructions for voting
  • Log in to the wiki if you are not already logged in.
  • Scroll down to voting and click 'Edit source'. Copy and paste the appropriate code from this table on its own line at the bottom of the text area:
To get this output you type Description
  • I approve this proposal I approve this proposal.
{{vote|yes}} --~~~~ Feel free to also explain why you support proposal.
  • I oppose this proposal I oppose this proposal. reason
{{vote|no}} reason --~~~~ Replace reason with your reason(s) for voting no.
  • I abstain from voting but have comments I have comments but abstain from voting on this proposal. comments
{{vote|abstain}} comments --~~~~ If you don't want to vote but have comments. Replace comments with your comments.
Note: The ~~~~ automatically inserts your name and the current date.
For full template documentation see Template:Vote. See also how vote outcome is processed.


  • I approve this proposal I approve this proposal. Warin61 (talk) 22:24, 16 July 2018 (UTC)
  • I oppose this proposal I oppose this proposal. We should be using a generalisation of stream=* instead of this --Adavidson (talk) 09:34, 17 July 2018 (UTC)
  • I oppose this proposal I oppose this proposal. "at least 90% of the time" is impossible to be determined by mapped and is a completely arbritrary value. ephemeral=dry_season has no obvious meaning (is it tagging that waterways is ephemeral during dry season? Or is it tagging that waterway is ephemeral and may flow only during dry season? It requires careful reading of documentation to answer this question). --Mateusz Konieczny (talk) 14:30, 17 July 2018 (UTC)
  • I oppose this proposal I oppose this proposal. I am against this proposal because the seasonal=* tag already exists with the same idea. What needs to happen is that intermittent and seasonal tags need to be combined into one tag of intermittent. Just like building=yes, intermittent=yes would be the default choice if you do not have information about seasonal or ephemeral conditions of the intermittent body of water or cannot make a guess. Both the harmonized ideas of season and the ephemeral values could replace the yes value, if known. --Dr Kludge 08:30, 28 July 2018 (UTC)
  • I abstain from voting but have comments I have comments but abstain from voting on this proposal. Elaborating on intermittent water bodies is a good idea, but the proposed values do not seem right (ephemeral=dry_season is certainly impossible), and I do not see why we shouldn't use intermittent=* for new values directly (e.g. intermittent=episodic/wet_season/snowmelt/etc.). I don't vote "no" because I am not a desert expert. However, I'd like to point out that ephemeric waterways also exist in alpine regions where some brooks carry superficial water once every couple of years during heavy rainfalls. Maybe "wet_season" is not strong enough to express these rare conditions. --Fkv (talk) 19:39, 17 July 2018 (UTC)
  • I abstain from voting but have comments I have comments but abstain from voting on this proposal. The hydrography distinct in: perennial,seasonal,ephemeral and intermittent (waterway) streams. The use "ephemeral=yes" for waterflow only after heavy rainfall or snowmelt makes sense. But with some other proposed values like "wet_season" I have a problem. --Schröcker (talk) 15:06, 30 July 2018 (UTC)

Optional voting on a default of intermittent=yes for the key ephemeral STOPPED DUE TO REMOVAL OF MATERIAL! Will restart after corrections

Vote here as to if a default value of intermittent=yes should be stipulated with the key ephemeral.

Instructions for voting
  • Log in to the wiki if you are not already logged in.
  • Scroll down to voting and click 'Edit source'. Copy and paste the appropriate code from this table on its own line at the bottom of the text area:
To get this output you type Description
  • I approve this proposal I approve this proposal.
{{vote|yes}} --~~~~ Feel free to also explain why you support proposal.
  • I oppose this proposal I oppose this proposal. reason
{{vote|no}} reason --~~~~ Replace reason with your reason(s) for voting no.
  • I abstain from voting but have comments I have comments but abstain from voting on this proposal. comments
{{vote|abstain}} comments --~~~~ If you don't want to vote but have comments. Replace comments with your comments.
Note: The ~~~~ automatically inserts your name and the current date.
For full template documentation see Template:Vote. See also how vote outcome is processed.


  • I approve this proposal I approve this proposal. Warin61 (talk) 22:24, 16 July 2018 (UTC)
  • I abstain from voting but have comments I have comments but abstain from voting on this proposal. Let's be realistic; the chance that OSM Carto is going to start rendering anything other than intermittent=yes in the near future is small. Better to just think of it as another example of highway=bus_stop.
  • I oppose this proposal I oppose this proposal. intermittent=yes should be still added. Adding just ephemeral=wet_season is in my opinion like tagging isced:level=* without tagging amenity=school --Mateusz Konieczny (talk) 14:27, 17 July 2018 (UTC)
  • I oppose this proposal I oppose this proposal. intermittent=yes provides the needed information. The values for intermittent should be expanded as noted in the voting above. --Dr Kludge (talk) 19:43, 29 July 2018 (UTC)
  • I approve this proposal I approve this proposal. Redundant tags should be avoided wherever feasible. --Fkv (talk) 18:20, 17 July 2018 (UTC)
  • I abstain from voting but have comments I have comments but abstain from voting on this proposal. We are using "intermittent" for streams in a wrong way (meaning). See the discussion page on Key:intermittent. --Schröcker (talk) 15:06, 30 July 2018 (UTC)
  • I approve this proposal I approve this proposal. This is an important tag for dry/desert climates. --ClipArtJoel (talk) 01:42, 22 December 2018 (UTC)
  • I approve this proposal I approve this proposal. This is an important tag for abandoned ponds --AlexRiabtsev 18:45, 22 April 2021 (UTC)