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?
Javbw
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