Tag:waterway=rapids
 waterway = rapids
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| Description |
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A fast-flowing and turbulent section of a waterway which is not a waterfall. 
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| Group: waterways |
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| Status: de facto |
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The tag waterway=rapids is for individual rapids drawn as nodes or lines. A rapid is a fast-flowing, often turbulent section of a watercourse such as a river, often containing exposed rocks or boulders. For rapids drawn as areas, see water=rapids. For rapids as an attribute of waterways, see rapids=*.
Background
For boat safety, all rapids should be mapped as attributes of waterways using the rapids=* tag. However, additionally mapping rapids as separate features can help with use cases like rendering and geocoding.
How to map
An individual rapid or series of rapids can be mapped as a node, line, or area. Please do not map the same rapid with more than one type of geometry, as this results in duplicate features.
As a node
Add a node tagged waterway=rapids at the center of the rapid. If the rapid spans the whole river, the node should be shared with the waterway feature. If the rapid is off to one side and paddlers can bypass it in-water, the node can be a standalone point.
As a line
Draw a linear way along the crest of the rapid across the river (similar to waterway=weir). Connect the rapid line to the river centerline where they cross.
Note that this pattern is suitable only for very short rapids. For longer rapids, use the geometry of the waterway=river and add rapids info using the rapids=* tag and its namespace. Optionally, add the individual rapid as a node or area instead.
As an area
For the sake of consistency, rapids as areas are generally tagged with natural=water + water=rapids instead of a waterway=* tag. See Tag:water=rapids for guidance.
Useful combinations
You can use any OpenStreetMap attribute tags to describe the rapid. Some useful combinations include:
- name=* – the commonly-used name for the rapid
- description=* – an overview of the rapid useful to paddlers and other river users
- rapids=* – the difficulty grade of the rapid
- height=* – the overall drop of the rapid under normal conditions
- width=* – the total span of the rapid across the river
- length=* – the total distance of the rapid along flow of the river
- intermittent=* – if the rapid appears inconsistently
- seasonal=* – if the rapid only appears at certain times of year
- tidal=* – if the rapid is affected by tidal waters
Similar features
- waterway=waterfall – a vertical drop in a stream or river, generally not navigable by boats
- waterway=weir – an artificial obstruction with water usually flowing over the top
Alternative tagging
Historically, several alternate patterns have been used to tag a rapid or series of rapids. The most common of these has been whitewater=rapid (and its typo whitewater=rapids). These tags have the disadvantage of implying all rapids are whitewater, and of expecting data consumers to treat whitewater=* as a primary type tag. This pattern also doesn't discriminate between rapids as attributes of rivers versus rapid as individual points of interest.
Another pattern has been to use one or more of the whitewater: namespaced tag on a feature to indicate a rapid, but without any primary type tag. Such tags have included whitewater:rapid_grade=*, whitewater:section_grade=*, whitewater:grade=*, whitewater:rapid_name=*, whitewater:rapid_name=*, and whitewater:name=*. This tagging pattern is not used for any other type of OSM feature and makes rapids extremely difficult to query.
For attributes, mappers have used a mix of regular tags and whitewater: namespaced tags. Regular tags are preferable, since very few apps know about whitewater: tags.