[Tagging] [Tagging ] How to tag a paleochannel of a river

stevea steveaOSM at softworkers.com
Sat Mar 13 08:50:51 UTC 2021

A fascinating discussion, as I know oxbows in rivers and the oxbow lakes they might create, though I am unclear on why or whether OSM might, do or should tag these.  Usually in cases like these (this is me, but I think it wide practice), I tend towards the side of "be generous, allowing the wider, more expansively-described tagging."  So, "yes" to oxbow, whether on a river or as a lake created by what I understand to be "the oxbow process."  A hydrologist could fully explain this process (which is part geological, part hydrological, IIRC).  As Bert suggests, a wiki about this might also describe a hydrologist-informed lifecycle including that these can and do turn into swamps over a decades-to-centuries time scale.

Similarly, polder.  There is such a thing and I'm a bit surprised we haven't developed a tag for it (even if it IS simply landuse=polder), although let's be careful with landUSE as a key for this, it might imply all polders "act like a polder," which may or may not be true.

What I have never heard before is "paleochannel," and US English is my native tongue.  (The word does not appear in my US English dictionaries, either).  I'm sure it is really "something," (perhaps only in a highly specialized or technical realm, it has that sort of feel about it) though how it differs from "oxbow," I don't know.  But "oxbow" is a real word.  (It is also a U-shaped collar of an ox yoke, hence being applied to rivers and the lakes resulting from the oxbow geological / hydrological process).

There is also something about a river called the "thalweg" (German, valley/dale + way) meaning "a line connecting the lowest points of successive cross-sections along the course of a valley or river."  Some places use this as a more-exact legal boundary in larger rivers that define boundaries.

Fascinating, the places OSM goes.

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