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Van Tuyl Lecture: Travis Swanson, Rice University
September 20, 2018 @ 4:00 pm - 5:00 pm
Travis Swanson, Rice University
241 Berthoud Hall, 4PM
Topic: Exploring the Morphodynamic Response of Coastal Barriers to Sea-Level Rise along the Texas Gulf Coast
Abstract: The Texas portion of the Gulf Coast spans nearly 600 kilometers and is chiefly composed of barrier islands and peninsulas that shelter bay environments and numerous coastal communities from damaging storm surge and waves. Presently, this coastal barrier system is evolving at an unprecedented rate, as sediment that comprises these protective barriers is being depleted while sea-level rise is accelerating, reducing the resilience of coastal communities. To forecast the morphodynamic response of Texas’ coastal barrier system to anticipated rates of relative sea-level rise, a reduced complexity morphodynamic model is constructed from a combination of extant models of barrier morphodynamics, alongshore sediment transport, and time-variable ravinement depth. The model is initialized using a simplified geometric depiction of Texas’ coastal barrier system morphology obtained from regional bathymetric and topographic surveys, and sediment composition from best-available subsurface geodatabases. Simulation timesteps capture the morphodynamic response of coastal barriers to accelerated sea-level rise by tracking the motion of key geomorphic boundaries within the barrier system: ravinement depth, shoreline, and bay line. The motion of these boundaries is calculated via parameterized expressions of alongshore, cross-shore, and barrier over-wash sediment transport that represent the time-integrated effect of short-term coastal processes, such as day-to-day waves and storms, and longer-term processes such as sea-level rise, dynamic barrier morphology, and barrier sediment composition. Model results are within reasonable agreement with historical records and geological interpretations of regional coastal change sampled over a broad range of time and spatial scales.