re: 7.7 million households in the 7 Cal. counties affected by the flooding, 52K have flood ins

One easy fix is to not allow building flat to the ground.

Elevation is your salvation. Give yourself 1-3 feet of freeboard in the form of a hill or pillings from the natural elevation. If you build a basement, build it with no windows and 1 to 3 feet of clearance over the ground to not allow water in.

Sometimes a foot is the difference between flooding and not.

Just look at New Orleans last week. If places were a foot higher the rain would not have flooded that many homes or businesses. Cars maybe a different story since they are on the street.