1880 to 2005 Morphologic Evolution of a Transgressive Tidal Inlet, Little Pass Timbalier, Louisiana

Rates of relative sea level rise in excess of 1 cm/yr are forcing rapid landward migration of barrier/tidal inlet systems along coastal Louisiana. Additionally, the conversion of interior wetlands to open water increases tidal prism, resulting in barrier degradation by means of increased inlet cross-sectional area and sediment sequestration in ebb tidal deltas. Historical bathymetric maps (dating to the 1880's) and up-to-date bathymetric data for Little Pass Timbalier provide a time series that shows the morphological evolution of this tidal inlet. The historical evolution includes: landward and lateral migration of its main channel (44 m/yr and 28 m/yr, respectively); changes in inlet throat geometry; and formation of a new stable ebb channel. The inlet throat cross-sectional area increased from 3,117 m² in 1880 to 17,510 m² in 2005. The ebb tidal delta is prograding seaward leaving a quasi-progradational sand body on the inner shelf as the barrier islands migrate landward.