Very few homes flood, however. I heard about flooding recently, when a developer changed (removed) a levy system that was protecting homes that were at a lower elevation. The homes "downstream" were getting flooded, due to the change several miles away, years after they were built and never having problems. The problem was corrected, of course, but that doesn't help the poor home owners that were living under water.
It does flash flood in AZ, but homes built in the later years should all have been built to withstand a 100 year flood. Older homes often are more apt to be flooded, simply because they have not been built up. Whether or not it is more likely to flood here then in SF..... I do not know how apt to flood SF is so I couldn't answer that, but my guess would be probably not.
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