An apparently very wise Native American said long ago that all natural disasters were due to the ignorance of white men.  This is exactly what he meant.  Heavy rains and flooding rivers, aside from those caused by human-induced global warming, are totally natural.  What makes them harmful is the selfish and idiotic insistence on living in flood plains and trying to contain rivers with levees instead of letting them flood and recede naturally.  And of course, anything caused by human induced global warming is obviously part of the ignorance.

The plowed-up prairies, drained fields, altered streams, no-longer-wetlands, and developed flood plains also offset the net charge of the area.  This shift in charge attracts storms electrically.  After the flooding subsides it should be noted that life will regain the area and stabilize it.  This took place the last time there was flooding there, but then human stupidity and greed took over and here we are again.

Turn those former wetlands back into wetlands, they will absorb and cleanse the storm overflow, as it gradually works it's way into the aqufier.

Put flood gates in the sides of the rivers, instead of damns, then let overflow go into resevior/wetlands.  Keep the levies that protect cities and drain the water away from them with this wetland restoration.