Am Mo., 14. Okt. 2019 um 09:43 Uhr schrieb Joseph Eisenberg < [email protected]>:
> > If it is a valley, wouldn’t there be water at some time, even if very > rarely? > > Off the top of my head, there are at least 3 types of valleys that > never contain running water: > > 1) Valleys in karst formations, where all surface water disappears > into cracks or holes in the limestone and flows underground. There are > several moderately large valleys like this near me, where there is no > visible surface watercourse, even though my area receives over 200cm > of rain a year. > > 2) Valleys in cold climates where the temperature never is above 0 > degrees. There are a number of dry valleys in Antartica like this, as > well as in some high-elevation Alpine areas. > > 3) Valleys in very dry climates, where there is never sufficient rain > for surface flow of water. The deserts in southern Peru and northern > Chile are like this. Many small valleys there are formed by wind or > motion of fault lines or plate tectonics, not by flowing water. > right, there are some exceptional cases. Maybe the waterway=wadi tag still applies to some of them, for example wikip.en explains that water in wadis may be ephemeral or sub-surface: https://en.wikipedia.org/wiki/Wadi > > (In most dialects of Arabic, the word "wadi" وَادِي means "valley", > not necessarily a dry watercourse as in English.) > yes, but the tag is waterway=wadi, so there is a reference to watercourse. It doesn't mean that there must be water at every time of course. Cheers Martin
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