Storm surge is a pretty big deal with hurricanes. Heavy rain and wind can wear down natural and mad-made objects in the path of a hurricane, but storm surge is just as big a deal (if not more) in areas that are situated near the coast. If the town that you live is basically at or near sea level--like Galveston or New Orleans--a storm surge of 15 feet it obviously going to be devestating, even without the wave action.
But check out this graphic from the National Hurricane Center showing the maximum storm surge for Hurricane Ike. Looking at the graphic (which may change over time with the forecast... I've saved it in case any wants to see it), model guidance shows an appromiately 13 foot storm surge for Galveston Island. The international airport at Galveston is at an elevation of 6 feet.
This is guidance and may not actually be as bad as this. It is a sobering look at one possible outcome and useful tool as well.