Talk:Key:tidal

Clarify common tagging mistakes

Based on my understanding of the current documentation, this tag should only be applied to the sections between high and low tide marks, ie the tidal range. However it appears myself and other mappers have interpreted it as mapping features affected by tides. For example 71707142 71707142 has the whole section of the waterway from the tidal limit through to where it reaches the ocean as tidal=yes since this is the section affected by times and within the tidal limit which according to the documentation is wrong? I see value in a way to tag a waterway or body of water as being affected by ocean tides, separate to a way of marking the area between low and high tides. Aharvey (talk) 00:02, 23 January 2025 (UTC)

Would assume it's an approximation at first. Don't know, or don't want to split at the low tide.
The naming of tidal=* isn't fully self-contained. Agree another tidal=* could be invented for the section below the low tide.
—— Kovposch (talk) 08:27, 23 January 2025 (UTC)

The tidal range of a river (or the tidally influenced range of a river) is the part of a river where water flow or water levels systematically depend on the tidal cycle. In case of the example of the Moruya River the tidal influence probably ends somewhere around the upper end of the Batemans Marine Park.

This is also the common understanding of the meaning of the tag when applied to waterways - though it is not always accurately represented in mapping practice. But this - from what i can see - is not caused by mappers following a different idea of the meaning of tidal=* but based on a lack of local knowledge. Someone might have looked at the river further upstream during dry season, seen dry sandbars and therefore incorrectly inferred that there is a tidal influence.

It would probably be useful if the concept of the tidal range is explained more clearly, especially the fact that this is a dynamic phenomenon and that you cannot just go to a location on the open coast, measure the elevation of the high water mark and then extrapolate the contour line of that elevation as the universal limit of the tidal range of rivers in the region.

--Imagico (talk) 11:10, 23 January 2025 (UTC)