|地物 : 滝|
滝は水路（waterway）上のノードに waterfall として示し、滝の崖を表すウェイを作成します。
- （ノード） waterway=waterfall + name=* + height=* + width=*
- （ウェイ） natural=cliff （または、人工の滝には waterway=weir / waterway=dam）
- 水路のノードを waterway=waterfall とタグ付けし、分かれば name=* + height=* をタグ付けします。 JA:tag:waterway=waterfall も参照してください。タグ付けされたノードは滝の縁と共有するべきであり、すなわち両方の地物が滝の一部となります。滝の地図記号がその場所に表示されることを意図しており、レンダラーによってはその通りに動作します。
- additionally, a section of the waterway can be tagged with whitewater_section:grade=*, or the new alternative whitewater:grade=* if it is relevant to whitewater sports. See also open issues
- deprecated, historic usage: tag a section of the waterway as waterway=waterfall. This has been part of Proposed features/Waterfall which has been changed and abandoned since then.
The cliffs forming the waterfall edge are drawn as a way and tagged as natural=cliff, drawing direction should be so that upstream is on the left side. The cliff should share a node with the crossing waterway and this node should be tagged with waterway=waterfall as described above.
This is currently rendered as cliffs across the river, though the renderer may detect that it is actually a waterfall edge and render it in a special way.
Waterfalls can be also artificial or include man made elements such as weirs or dams, these can be tagged as waterway=weir and waterway=dam instead of cliffs, with the same rule about shared node as above.
Sometimes a waterway=waterfall has been also applied to an area of water delineating the actual area where water is falling, this area also often closely resembles the cliff area so the two flags have been used together. However this scheme does not seem to be defined anywhere.
The width currently is defined by the river width or riverbanks.
- Victoria falls - http://www.openstreetmap.org/way/40894259
- Rhine falls:
- Niagara falls: one part of the cliff forming the waterfalls - http://www.openstreetmap.org/way/217355188
- Lago Molveno: here the water arrives through an underground waterway=canal to flow under the bridge before it falls over the weir (http://www.openstreetmap.org/way/249350122) into the mostly natural lake.
- natural=bare_rock - for an area with solid bare rock cover
- natural=scree - for an area of loose rocks
- natural=stone - for single freestanding stones (single node)
- natural=cliff - for a rock face
- waterway=fish_pass - allows fish to circumvent dams, weirs and maybe waterfalls
Please discuss on talk page
- tagging the waterfall-edge as natural=cliff is logical and rendered nicely, but it may be a good idea to mark the waterfall edge additionally. The shared node marked as waterfall may or may not be enough. As it is a special type of cliff it could have an additional waterfall_edge=yes. It could be rendered as a cliff with superimposed bubbles or blue curly lines across it.
- the status of whitewater:grade=* is unclear - it is used even though the proposal seems to have been abandoned, wiki needs cleanup regarding this
- whitewater_section:grade=6 has been used to tag waterfall section of the river at the Rhine Falls (see examples). The Rhine Falls have been navigated by kayaks so this seems logical. The question remains if that is appropriate for other waterfalls which for various reasons (too little water, too high) will never be navigable by any craft. Possible options:
- use whitewater_section:grade=waterfall: pro - known tag and it is a kind of whitewater. contra - tag only defined for ways
- use a new tag to mark a node/way/area that would define the point/way/area where the water is falling
- White water classification follows its own subjectives rules not only described by these pictures, see International Scale. If you don't know about river practise on a particular river, don't map it at all.
- The old proposal had a complicated history partly explained in here and was withdrawn because a de-facto usage emerged which addressed most needs.
- Whitewater sports and WikiProject Whitewater Maps for details regarding whitewater_section:grade=waterfall
- https://github.com/gravitystorm/openstreetmap-carto/issues/336 - opencarto rendering
- https://trac.openstreetmap.org/ticket/2954 - mapnik rendering issues with long history and many examples.
- https://wiki.openstreetmap.org/wiki/WikiProject_Whitewater_Maps/Proposals - somewhat forgotten proposal
- withdrawn - Proposed_features/Waterfall