[Tagging] Waterway equivalent of noexit=yes?

Paul Allen pla16021 at gmail.com
Wed Aug 12 11:49:50 UTC 2020

On Tue, 11 Aug 2020 at 19:19, Tod Fitch <tod at fitchfamily.org> wrote:

> It occurred to me that the area where water flow disappears is
> indeterminate [1], thus the problem mapping it.

Ordnance Survey represents this as a sort of star of very short waterways
at the approximate point of disappearance and labels them "spreads."

The map is representative.  We can tolerate precisely specified amounts of
doubt and uncertainty.  The name "spreads" indicates the indeterminacy even
if we map it as a node.  Just as we render a spring as a circle on the
map, an asterisk would do for spreads.

Perhaps a “indeterminate=yes” tag on the last node of a water way that
> “peters out” [2] could be used to signal the QA tools that the end of a
> water way is not a mistake.

If we tag it as waterway=spreads the indeterminacy is implied and QA tools
can be happy there is no mistake.

> Might be useful in cases other than an ephemeral water way in the desert
> though I haven’t thought of one yet.

Useful in coastal waterways that peter out in sand above high water.  Or
waterways that peter out in sand just below high water when the tide is out
- they
haven't carved a channel down to the low water mark, they just vanish into
sand (but QA tools won't have a problem with those if they connect to the
water mark).  And yes, there are coastal waterways that carve a channel
a beach right down to low water and others that just peter out on the beach
close to high water.

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