|Tag used for further classifying streams|
|Used on these elements|
|Tools for this tag|
The stream tag is used fairly commonly to further classify a stream which has already been tagged with waterway=stream. The most commonly used values as of the time of writing describe continuity of flow throughout the year:
|intermittent||The stream only flows for part of the year, for a few weeks or months. See also intermittent=yes, which has the same meaning, or seasonal=*|
|ephemeral||The stream flows only during and briefly after precipitation, i.e. for a few hours or days. There's no precise demarcation between an epemeral stream and surface run-off.|
|perennial||Water flows all year round .|
|permanent||Presumably the same meaning as "perennial".|
|dry||A dry river bed. Better to tag as ephemeral or intermittent if known (see below too)|
|*||See TagInfo for a list of other values in use. These tend to be used more for the type of stream, although the values tend to be broken up by variety in synonyms.|
The table above documents current usage only. You can help by expanding it to cover newly-emergent typing of streams.
When distinguishing between perennial, intermittent and ephemeral streams, it may be better to use intermittent=* and not stream=intermittent:
- There exist waterways which are too wide to jump and which are therefore tagged as waterway=rivers, but which are still dry for part of the year.
- Without tags to the contrary, natural waterways should be considered perennial.
- Ephemeral streams may suffer from a lack of easy verifiability; decide carefully whether such minor, indistinct rivulets are worth mapping and whether other mappers would arrive at the same decision.