Do you love big bluegill?
So I normally fish some pretty heavily pressured waters here, but recently we had some MAJOR flooding, and I was wondering would this flooding push all of the fish out that have been subjected to all of this pressure, and therefore new fish that have not been subject to any fishing pressure take their place, and in turn make it almost like an unpressured body of water?
Hgh water events can absolutely move fish around. But, the flip side to that coin says that any new arrivals MIGHT take a little time getting used to their new digs before they put the feedbag on, and you take the good with the bad....including little fish which may be more susceptible to water movement, a possible influx of less desireable fish, and an alteration of the predator/prey relationship.
Having said that however, when I was a boy I fished a creek that ran through our cow pasture...nearly everyday. I loved flood events, for just the reason you mentioned. It was almost like fishing a new body of water again.
Current flow stirs up the bottom, which activates the food chain from the smallest scavengers and bait up to the largest predator in the system. If the water rises enough, and floods vegetation, fish will move into the vegetation to feed. Springs floods that raise a stream up onto the grassy floodplain are a prime time to sight-fish large predators. When you see a fish roll, toss a rig with several nightcrawlers on the hook to the fish. It should hit almost immediately. Storms drains the dump into a body of water are often hot-spots when they are flowing. They wash worms, bugs, and other things into the water. A hot method to fish this is to attach enough split shot to the line to get your bait to bottom, but no pin the bait there. Put a nightcrawler or two on the hook, cast out, and left it drift. If fish are actively feeding, you should get a hit immediately. If you have eddies, toss a float rig in there and let it drift. Be careful if there's a lot of debris in the water.
It may take a few years of fishing in rising- and falling-water conditions to establish patterns of your body of water. Keep records.
It is VERY true the fish move in floods. The high water allows the fish to move up and over obstacles blocking upstream passage. It will also wash fish from upstream pools into downstream pools, should they get caught in the current. I've seen both happen. I've seen fish go over dams, caught in the current. One of my favorite creeks (lots of hungry sunnies) had a couple Koi in a lower pool Sometime this summer, there was a small flood. I noticed that the high-water line had moved. Then, I spotted both Koi in the upper pool.