The Impacts of Hurricane Ivan at Pensacola Beach, FL

摘要

In the morning hours of Sept. 16, 2004, Hurricane Ivan made landfall in the Gulf of Mexico west of Gulf Shores, AL. The strong Category 3 storm produced sustained hurricane-force winds that extended eastward alongshore more than 105 miles and produced storm surge levels of 10-15 feet, overtopping the barrier beaches of Baldwin County, AL, and Escambia County, FL, in most locations. This paper summarizes the effects of Ivan upon the coastline at Pensacola Beach, FL, approximately 40-45 miles east of landfall, with a particular focus on the impacts to the sandy beaches. The storm caused significant damage to a recently constructed 8.1-mile, 4.25-million cubic yard beach restoration project, destroyed many homes and other structures, disrupted utility services for several months, and produced more than 1.3 million cubic yards of recoverable overwash sand and debris islandwide. Along the Gulf of Mexico shoreline, comparisons of pre- to post-storm beach profile survey data indicate that 3 million cubic yards of sand were transported from beaches located within the project limits (roughly 70 cy/ft (cubic yards per foot), average). Almost 50 percent of that volume is estimated to have been transported landward into upland areas. Shoreline recession averaged 53 feet at Mean High Water (MHW). Higher elevations of the beach retreated by over 200 feet as the beach was reshaped into a near-planar configuration with typical seaward-dipping slopes of 1:35 (vertical: horizontal). Post-storm recovery efforts, aided by post-disaster financial assistance from the Federal Emergency Management Agency (FEMA), have resulted in the retrieval, sieving, and beach replacement of more than 1.2 million cubic yards of sand. Similarly, over 150,000 cubic yards of construction and demolition debris have been removed from the 1,474-acre limits of Pensacola Beach. In addition to the replacement of a portion of the displaced sand, repairs to the beach include a comprehensive renourishment of the 2003 beach restoration project, scheduled to begin in summer 2005.