All good input. As to the recurring frequency of 100-500 year events, I too see this. I live on a semi-rural property (20 acres) with lots of hills, and hence drive/drainage issues. Fortunately my house is elevated on a plateu, but I have begun to "harden" alot of my drainage ditches, culverts and the like as I too feel we have more extremes occuring. We had 5" of rainfall in 2 hours a few years back from a "stalled" evening thunderstorm. ALOT of damage, raging torrent of water here. Good planning to keep all this in mind.

Ironwood