Historical Morphologic Evolution and Sedimentation at Barataria Pass, Louisiana

by Adam J. Shamban, B.P. America Exploration, Houston, United States,
Thomas F. Moslow, B.P. America Exploration, Houston, United States,

Document Type: Proceeding Paper

Part of: Coastal Sediments


Barataria Pass, Louisiana, one of the most commercially important tidal inlets in the Gulf of Mexico, has undergone several stages of development since 1840. The shore-parallel growth of the updrift barrier island (Grand Isle) has diverted the flow of two back-barrier tidal channels (Bayou Fifi and Bayou Rigaud) to form a junction with the main tidal channel draining Barataria Bay. Major hydraulic turbulence and scour occurred in this area during the exchange of tidal flow. As a result, the bay side of the inlet channel migrated, reorienting tidal currents and the downdrift barrier island (Grand Terre) shoreline. From 1888 to 1934, scour and an increasing the throat area enlarged the inlet channel, increasing the throat area 73% and creating a scour hole 50.3 m deep at the tidal channel junction. During the same time period, the ebb-tidal delta at Barataria Pass grew by 12.3%. An equilibrium shoreline profile of the inlet-barrier system associated with Barataria Pass was established by 1934 and maintained until 1958, when a jetty constructed on Grand Isle disrupted inlet sedimentation processes. This caused the erosion of the spit immediately downdrift of the jetty, thus widening the pass. By 1964, the inlet channel had widened by 48% and shoaled 6.1 m. Jetty extension in 1964 caused Grand Isle to prograde seaward 425 m along the jetty's length, giving Barataria Pass an updrift offset configuration by 1971. Since 1971, continued longshore sedimentation has overtopped the jetty and built a recurved spit into the inlet, reducing the throat width by 38%.

Subject Headings: Scour | Sediment | Barrier islands | Bays | Shoreline | Tides | Sea water | Channel flow | Louisiana | United States | Gulf of Mexico

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