today's M-W word-of-the-day reveals an interesting sense drift for the word debacle, which originally meant a sudden breakup of ice on a river. http://www.m-w.com/cgi-bin/mwwod.pl

And the related older meaning of "the flood" for "debacle" I'm sure I've seen somewhere....

Apres moi, le déluge.....
I had never heard the "ice break-up" derivation before.
debacle - "disaster," 1848, from Fr. débâcle "breaking up of
ice on a river," figuratively extended to the violent flood that
follows when the river ice melts in spring, from débâcler "to
free," from M.Fr. desbacler "to unbar," from des- "off" +
bacler "to bar," from V.L. *bacculare, from L. baculum
"stick." Sense of "disaster" was present in Fr. before Eng.
borrowed the word.

I never knew the ice-break-up meaning either--thank you. Now: why isn't it pronounced DEB-ah-cull?

Since verb is "bacler", no reason to attach the dé to the "b" of "bacler".