Weir does not seem appropriate for this type of thing. There is a tag, waterway=spillway, that seems like a good fit - 81 uses so far.
You could also add emergency=yes to the above or create a new tag, emergency=spillway Cheers Dave On Wed, Mar 22, 2017 at 12:25 PM, Mark Wagner <mark+...@carnildo.com> wrote: > On Wed, 22 Mar 2017 10:44:17 +0900 > John Willis <jo...@mac.com> wrote: > > > How do you tag an emergency spillway? > > > > I am tagging a giant flood control reservoir in my region. The “lake” > > is surrounded by giant man-made embankments on all sides, surrounded > > by an additional set of embankments, with gates to let the water > > out. There is no dam per se, because there is ~200 km of this > > man-made 10-20m tall earthen embankment (levee) around the entire > > river system - it is part of that. > > > > When this levee system fails uncontrollably (like it did downstream > > from me in 2015), it is really bad. > > https://www.youtube.com/watch?v=Hfs3OeqiqRk > > <https://www.youtube.com/watch?v=Hfs3OeqiqRk> > > > > This reservoir system catches water during a typhoon from a smaller > > river, then releases it slowly after the peak flooding into the > > larger river. this reduces the chance of flooding further > > downstream. > > > > However, it has 2 sets of emergency spillways (each about 1Km long) > > to let water out of both sets of embankments, so where it “fails" can > > be controlled. it is 5 m lower than rest of the embankments > > surrounding the reservoirs. These were recently added. > > > > I made a polygon on one such spillway. > > https://www.openstreetmap.org/way/481898093#map=14/36.2115/139.6880 > > <https://www.openstreetmap.org/way/481898093#map=14/36.2115/139.6880> . > > the heart-shaped lake is the reservoir, and most of the surrounding > > green areas are part of the flood control basin made by the second > > set of levees. > > > > These *emergency* spillways are considered safety features of most > > large water control projects - if the human-controlled gates o the > > normal spillway jam shut, the emergency spillways will keep the > > dam/embankments from being over-topped in unexpected places. I know > > these are a major mappable feature of large dams, but they are not > > mentioned on the Dam wiki page. Maybe I am looking at it wrong. > > > > As these are not a weir, nor a normal path for water to go, I > > wouldn’t tag them as a weir nor as a object normally associated with > > a waterway line running through it. > > > > is there an existing tag or another name for these features that I > > don’t know of? How do I tag these emergency spillways (and heck - > > these huge levee embankments!) correctly? > > For what it's worth, Oroville Dam > (https://www.openstreetmap.org/#map=17/39.54412/-121.49263) currently > has its emergency spillway tagged as a weir. > > -- > Mark > > _______________________________________________ > Tagging mailing list > Tagging@openstreetmap.org > https://lists.openstreetmap.org/listinfo/tagging > -- Dave Swarthout Homer, Alaska Chiang Mai, Thailand Travel Blog at http://dswarthout.blogspot.com
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