Yes, you are correct. Soon after I typed what I said above, I saw a report on MSNBC that clearly stated the Galveston sea wall is 19 ft high, however they were predicting a 19-20 ft storm surge at a time that Rita still had a pressure considerably higher than 900mb. Also, I believe the newer parts of Galveston--those that were populated in recent years with expensive vacation homes, are on lower ground (although most of the homes themselves are on pilings) and not protected by the sea wall. Therefore, my point I think remains--all of Galveston's protections could be overtopped by the storm surge of a Cat 4 storm leaving a Biloxi-type scene, not just "erosion" as someone said Jim Cantore was suggesting.