Waves and Currents During a Winter Cold Front in the Mississippi Bight, Gulf of Mexico: Implications for Barrier Island Erosion

Abstract

This study uses numerical models to predict waves and currents in the Mississippi bight, Gulf of Mexico, for the period 4 to 7 March 1997, during which time a cold front passed over the region. The models are validated using observations from the area. The simulated waves and currents are used to infer littoral transport paths along the soundside of the barrier islands fronting Mississippi Sound and Chandeleur Sound. Predicted waves along the soundside of the barriers reach heights of 0.9 m with wave periods less than 4 s. These steep waves are important for eroding the soundside of the barrier islands. Currents near the barrier islands within Mississippi Sound are dominated by tidal flow. Consequently, shoreface transport within this estuary is sensitive to the tidal stage as well as wind direction and strength. Wave-driven littoral transport cells within Mississippi Sound are inferred to have been eastward during the frontal passage phase and westward as the wind became northeasterly during the post-frontal phase. This result suggests that sediment eroded from the barrier islands was continuously transported into tidal inlets. The model results also suggest that a southward wave-driven longshore drift cell was established along the soundside margin of the Chandeleur Island chain, with spillover onto the Gulf side of the southern islands.