On Tue, 11 Aug 2020 at 19:19, Tod Fitch <t...@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 coastal 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 the sand (but QA tools won't have a problem with those if they connect to the high water mark). And yes, there are coastal waterways that carve a channel through a beach right down to low water and others that just peter out on the beach close to high water. --- Paul
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