Simulation of storm surge, wave, currents, and inundation in the Outer Banks and Chesapeake Bay during Hurricane Isabel in 2003: The importance of waves

Abstract

This paper investigates the effects of waves on storm surge, currents, and inundation in the Outer Banks and Chesapeake Bay during Hurricane Isabel in 2003 through detailed comparison between observed wind, wave, surge, and inundation data and results from an integrated storm surge modeling system, CH3D‐SSMS. CH3D‐SSMS, which includes coupled coastal and basin‐scale storm surge and wave models, successfully simulated measured winds, waves, storm surge, currents, and inundation during Isabel. Comprehensive modeling and data analysis revealed noticeable effects of waves on storm surge, currents, and inundation. Among the processes that represent wave effects, radiation stress (outside the estuaries) and wave‐induced stress (outside and inside the estuaries) are more important than wave‐induced bottom stress in affecting the water level. Maximum surge was 3 m, while maximum wave height was 20 m offshore and 2.5 m inside the Chesapeake Bay, where the maximum wave‐induced water level reached 1 m. Significant waves reached 3.5 m and 16 s at Duck Pier, North Carolina, and 1.6 m and 5 s at Gloucester, Virginia. At Duck, wave effects accounted for ∼36 cm or 20% of the peak surge elevation of 1.71 m. Inside the Chesapeake Bay, wave effects account for 5–10% of observed peak surge level. A two‐layer flow is found at Kitty Hawk, North Carolina, during the peak of storm surge owing to the combined effects of wind and wave breaking. Higher surge elevations result when the 3‐D surge model, instead of the 2‐D surge model, is coupled with the 2‐D wave model owing to its relatively lower bottom friction. Wave heights obtained with 3‐ and 2‐D surge models show little difference.