I would start with the direction as flowing from the spring/rainfall source, then add the oneway=no as suggested. This gives a nominal source-destination flow, even if it is later modified by conditions (manmade or natural)
A clearer example is a tidal basin. The normal flow will be out to sea, but due to tides will also flow in reverse. On Sat, Apr 28, 2012 at 5:19 PM, Alexander Roalter <[email protected]>wrote: > On 04/28/2012 09:23 PM, Paul Norman wrote: > >> From: Nathan Edgars II [mailto:[email protected]] >>> Sent: Saturday, April 28, 2012 2:24 AM >>> To: Tag discussion, strategy and related tools; OpenStreetMap talk-us >>> list >>> Subject: [Talk-us] Waterway directionality in drainage canals >>> >>> It's the standard to draw a waterway in the direction of flow. I've >>> questioned this several times, but it's an ingrained default. >>> >>> My question is more specific: what happens to a drainage canal that >>> reverses direction? I offer the Everglades and surrounding agricultural >>> land as an example. There are huge "water conservation areas" that store >>> water. When it rains, gates are closed and opened to direct water into >>> these. During a drought, gates send water back out into the canals for >>> local use. When there's a big storm, water will instead go directly out >>> to sea. >>> >>> So there are a lot of major canals that have no fixed direction. How >>> should these be mapped? Is there any existing scheme that can show how >>> water flows under different conditions? >>> >> >> The same issue came up with minor drainage ditches and cranberry fields >> here. They're used to drain sometimes and sometimes to flood the field for >> harvest. >> >> I came up with the proposal >> http://wiki.openstreetmap.org/**wiki/Proposed_features/**directional<http://wiki.openstreetmap.org/wiki/Proposed_features/directional>for >> directional=* but it's abandoned. >> >> One weakness with the proposal is that unknown values are a special case >> of >> directional=no, not directional=yes >> >> > How about the oneway property? That is already often used on rivers (not > so often on streams), but an explicit "oneway=no" would specify that water > may flow in both directions... Just an idea. > > > -- > Cheers, > Alex > > > ______________________________**_________________ > Talk-us mailing list > [email protected] > http://lists.openstreetmap.**org/listinfo/talk-us<http://lists.openstreetmap.org/listinfo/talk-us> > -- Dale Puch
_______________________________________________ Talk-us mailing list [email protected] http://lists.openstreetmap.org/listinfo/talk-us
