I'm pretty sure the storm that just passed would have overflowed the Galveston seawall. It wouldn't breach it (Granite is good stuff) but it would have gone over the top and flooded the city.
Floods are a pain but nothing compared to a wall of wind driven water and debris stacked like a giant moving dike. That's what did it Galveston the first time.
Wow, Imagine a giant wall of debris stacked up like Rosie O'donnel bearing down on you.