Question:

Regarding all those communities and homes around Aurora and Denver and such that are having issues with flooding:

How many of those areas have flooded before? Say in the past 20 years? Past 50?  Before or after they were developed??

Or is this flooding "never ever happened before" flooding?

See, around here, it is the same areas (and the same houses) that flood every few years.
Bet it is the same there too.  This might be an unusual flood, but I'd bet significant money that is is not an unprecedented one.

There might be an unusual amount of water, and maybe even higher currents because mankind has channeled some of that water in a tighter area than nature intended....But those same areas have likely seen floods several times this century.

The fact is that this will happen again. People shouldn't live in these areas. If you live near a river, you can bet that AT SOME POINT the river will become unruly and will leave its banks.

If you live in area that floods, even occasionally, you can bet that your stuff will get wet. You may not be aware that such things have happened on the past, but the precedent is there.

Look: I understand flash floods. I've experienced them myself. But I don't LIVE in areas that experience them. If you choose to do so, then you have to deal with the consequences.  

And for Gods sake, don't drive into water that is deeper than the center of your tires, folks.