[Tagging] Additional detail of Levee mapping via embankments
johnw at mac.com
Thu Nov 14 03:06:54 UTC 2019
Sorry, I am continuing to have trouble properly replying to the tagging group, it keeps defaulting to the individual.
> On Nov 13, 2019, at 4:48 PM, Joseph Eisenberg <joseph.eisenberg at gmail.com> wrote:
> For a levee it can just go around the whole levee
If I understand your suggestion correctly, this is impossible. The only place one can “go around” is the finger of a levee that has ended where two rivers merge - but that is a lie too - the inside goes up the small river, and the outer folds and goes back upriver with it as well. There are very few places where inner becomes outer - because the point of the levee is to protect the outer from the inner. There are very few levees that end on the upstream side without going into terrain - still no option for the embankment to loop around. The levee starts in my town (sprouts out of a hill) and continues for 50KM. The river it meets goes for another 100km with full levee protection. They are giant structures. At no point does inner get a chance to become outer.
Every stream, tributary, and minor river has levees here. Some merge with “no” flow control. Others merge via culverts with underground sluicegates, others merge via gigantic sluice gates the size of an office building. But the gates still give no chance for inner to become outer. the flood basins I use have extensive weirs and 1Km emergency spillways in the levees - still no place for them to u-turn.
Having it “go around” is not really an option.
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