Drainage!
Most of our "flooding" is directly related to how we "develop" land.
Every square inch converted to human use created many times that much more loss of water absorbency.
Simple mandated adaption, caverns under parking lots, etc., already in use in some places, could prevent the growing flood effect much cheaper than the tax burden of clean-up.
Now you're in my area. turn cornfields and woodland into roofs and parkinglots, and you're shoving water downhill faster. Add in the tree huggers and Gubmint Greenies in the NRCS, DNR, Army Corp of Engineers, EPA, and Dept's of Environmental Management, they make it near to impossible to keep existing ditches, creeks, streams, and rivers clear of downed trees and obstructions.
Most developers strive to build so their runoff is directed towards someone else's development.