Key:tidal
 tidal
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| Description |
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An area in the tidal range. 
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| Group: marine |
| Used on these elements |
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| Useful combination |
| See also |
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| Status: de facto |
| Tools for this tag |
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The tag tidal=yes indicates that an element is in the tidal range. It could be a river, a shore, a part of a harbour or a water area.
When the part of the harbour has a gate which does not let the tide in you may tag it with tidal=no. But this is the default value so it is not really necessary.
How to map?
River
River flow
waterway=river + name=* + tidal=yes
River's water body
natural=water + water=river + tidal=yes
If you know where are the limits of the tide and of the river (because you have imagery at low tide and another at high tide), you can add 3 areas (closed ways or multipolygons), one for the river's water body and 2 (one on each side of the river) with tags natural=wetland + wetland=tidalflat (if these are muddy areas: you don't need in this case of tidal=yes) or natural=sand + tidal=yes (if areas are sandy) or natural=shingle + tidal=yes or any other tags (according to the type of soil) + tidal=yes.
Tidal area at sea
Areas in the tidal range between 
mean high water springs (natural=coastline) and mean low water springs can be tagged with tidal=yes to explicitly indicate this.
- Foreshore rocks body
natural=bare_rock + tidal=yes
- Foreshore sandy body (for example sandy tidal flats under water at high tide)
natural=sand + tidal=yes
Beaches can be partially or fully under water at high tide, thus natural=beach areas may extend beyond the natural=coastline. However, natural=beach is specifically for inclined, wave formed areas of loose sand or stones. Other types of terrain exposed at low tide should not use this tag.
If the foreshore is a mudflat, you may use the tags natural=wetland + wetland=tidalflat. These tags already imply that the area is in the tidal range so you don't need of tidal=yes.
Values
| Value | Description |
|---|---|
| yes | Indicates that an area is in the tidal range. The top of the tidal range is generally taken to be at natural=coastline; i.e. the mean high-water springs (MHWS). |
| no | Default. Disambiguates whether item is not in the tidal range or has not been considered for tagging. Not explicitly required. |
You can also add the type of this area: