it's a damn shame, but people fail to prepare for avoidable natural disasters, like floods. Loveland, Colo., Sept 2013

After the many floods in the past couple years that have been in the news, it's been shown that not getting a garage below the historic flood level prevents the majority of flooded cars. Making a simple ramp and elevated car parking with rail road ties also works, that puts cars at least 5 or 6 feet off the ground. Putting cars in BIG plastic waterproof bags works, etc etc. 

http://archive.boston.com/bigpicture/2013/10/dirt.html