What are you saying could be a reason for Ukraine to do this? The flooding is probably not fast enough to trap/kill soldiers at those positions. And while those

What are you saying could be a reason for Ukraine to do this? The flooding is probably not fast enough to trap/kill soldiers at those positions. And while those defensive positions will be "destroyed", they are replaced kilometers of marshlands, which is a superior defense, at least in the coming months. It can be held with much fewer people, shortening the effective length of the front, and freeing up soldiers to be used elsewhere. Massive gain for Russia, unfortunately. Likely nothing positive for Ukraine, unless they have something _incredibly_ creative going on.