Thread by @kddsky

4 days before the #KakhovkaDam catastrophe, the s-bridge support frames started breaking up probably at the edge of dam's concrete foundation. It might indicate erosion. That's missing in the @nytimes article.

Ruined support frames:

(@Maxar May 28 & Jun 5, via @ChristopherJM)

By these @planet images shared by @gbrumfiel it seems like the #3 support frame collapsed between 1-2 Jun, and #2 collapsed between 2-3 Jun

https://twitter.com/gbrumfiel/status/1665974703935180801

Roughly, there's 23 meters of dam downstream the sluice gates, after which sits a concrete stilling basin apron. And judging by this scheme — the weir and apron might be separate constructions.

And it seems like #2 and #3 support frames broke off around that weir-apron border.

If we assume that this is part of the erosion of the protective riverfloor layer, first indication of which we saw on Apr 28th — then we can suppose that the stilling basin apron is already damaged on Jun 1-3

https://twitter.com/kddsky/status/1669480941184483329

For reference:

Archive image of the river floor before the flooding. On the right is the wall-separator that will break by Apr 28th, white little blocks in the far are probably baffles at the end of the apron (also seen on the blueprints).

+ bridge support frames close-up

Also, what @jamesglanz @MarcSantoraNYT @LaurenLeatherby & co amazingly show in the article is the damage to the concrete weir.

What concerns me is why there's a v-shaped break of the weir? How can an explosion bend it downwards if riverfloor is intact?

pardon my clumsy drawings

cc @davidhelms570 @Gergyl @OSINTMISCIF @tom_bike @DraftnDepth

Bridge support fall was pointed out many times, I hope to add some ref to weir-apron connection. There's open question of why 2 & 3 didnt fell together, and why 1 didnt. Also, WDYT of the weir v-shaped break (or not)?

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