Proposal talk:Ephemeral

Meaning of 'short duration'

The source of ephemeral has a meaning of less than one day. Warin61 (talk) 02:24, 21 May 2018 (UTC)

Majority of the time dry

Most of the time ephemeral water features are dry, at least 45 weeks per year. Warin61 (talk) 06:09, 21 May 2018 (UTC)

The problem is where season is specified. Is the 'dry time' for that season only? Or is it for the year? I would take it as the year - except any part where the flow is continuous and tagged as continuous. For that reason I have changed the wording away from 45 weeks to 90%. The mapper needs to consider the year unless there is continuous flow for part of the year, then that part of the year can be excluded from the 90% requirement? Warin61 (talk) 22:44, 23 May 2018 (UTC)

I don't understand the definition yet. Above you say 45 weeks dry, apparently per year, which is 87% of 52 weeks, ok roughly 90%; thus about 7 weeks wet. So what period do you mean with "1 day for each water presence. The maximum duration... 7 days" on the proposal page? --Polarbear w (talk) 08:31, 17 July 2018 (UTC)

I have made the 'guide' more of a 'guide' rather than hard and fast 'rules'. The problem is that this is weather driven so on an average over 30 years it meats the requirement .. but in one year there might be 30 wet events and one of them is say 12 days.. but then dry for the next 15 years... So it has to be some sort of average? Warin61 (talk) 06:07, 12 December 2018 (UTC)

Ephemeral is now being used in the EU. I don't think any stream in the EU could be ephemeral! One definition is lacking surface flow for the majority of the year, with a minimum threshold defined as having flow for fewer than 35 days per year and pools holding water for less than 60 days per year. Warin61 (talk) 11:15, 10 April 2021 (UTC)

There are some streams near Kraków flowing only after major rainfall (I tagged them intermittent=yes without ephemeral=yes) Mateusz Konieczny (talk) 23:16, 10 April 2021 (UTC)

Determination guide

I have tried to produce a guide as to how to determine if something is ephemeral. If a feature cannot be determined then the tag should be left off. Warin61 (talk) 22:14, 21 May 2018 (UTC)

Seasonal values

The use of seasonal values gives a method of applying a restriction as to when ephemeral flows take place. Warin61 (talk) 02:24, 21 May 2018 (UTC)

It also allows for combinations with other types of flows. For instance a river that always flows in the wet season and ephemerally in the dry season could have the tags seasonal=wet_season with ephemeral=dry_season. Warin61 (talk) 02:24, 21 May 2018 (UTC)

Clarify relation with intermittent tag

There is "This should not be confused with intermittent, the key difference is the short duration of ephemeral" and there is nothing about "intermittent=yes". I propose to explicitly note that also intermittent=yes should be added, as ephemeral is a special case of non-permanent object Mateusz Konieczny (talk) 08:40, 27 May 2018 (UTC)

Rather than place a continuing and never ending burden on mappers, why not have it as an implication? In this way a render can chose to simply take it as the same as intermittent or render it a different way from intermittent. If both tags are present then the render has a more complex task of deciding which tag is to use and to check each and every intermittent tag for the tag ephemeral. Warin61 (talk) 03:36, 7 June 2018 (UTC)

"why not have it as an implication?" - because it is harder to support - from presets, to people editing and data consumers. Implications rarely work well Mateusz Konieczny (talk) 16:36, 7 June 2018 (UTC)

Default values are used for other things.. placing the work on an automated bit of code takes very little work .. but saves a whole heap of work for things like default speed limits. Warin61 (talk) 22:17, 7 June 2018 (UTC)

And default speed limits are one of cases where implications fail horribly (for start there is no way to distinguish "there is an implied speed limit here" from "nobody surveyed speed limit here") Mateusz Konieczny (talk) 08:32, 8 June 2018 (UTC)

So every road .. no every section of road (remembering tunnels and bridges) would have to have a speed limit on it. No way that is happening. Warin61 (talk) 08:43, 8 June 2018 (UTC)

It is happening. Otherwise, how you propose to distinguish "there is an implied speed limit here" from "nobody surveyed speed limit here"? Mateusz Konieczny (talk) 09:08, 8 June 2018 (UTC)

And oneway=no will have to be surveyed and add to every road too. Warin61 (talk) 02:48, 1 July 2018 (UTC)

oneway=no may be useful in places where oneway=yes is typical Mateusz Konieczny (talk) 18:49, 1 July 2018 (UTC)

Other water-related objects

This tag is useful for other water-related object in desert areas. Specifically to various water=* objects, man_made=water_well, and man_made=cistern. Zstadler (talk) 14:06, 23 December 2018 (UTC)