Predicting the Evolution of Tidal Channels in Muddy Coastlines

Abstract

Abstract : The long-term goals of this research are as follows: (1) to quantify the relationships between resuspension of fine material in the shelf by wind waves, tidal channel hydrodynamics, and sediment supply to coastal marshes; (2) to develop predictive, high-resolution models for the hydrodynamics and sediment dynamics of tidal channels in muddy coastal environments; and (3) to develop methods to predict the long-term evolution of tidal channels in muddy coastlines as a function of sediment availability, hydrodynamics, and climate change. The specific objectives of this research are as follows: (1) measure the supply of sediments to a Louisiana salt marsh as a function of wind waves; (2) apply, test, and validate a high-resolution, hydrodynamic sediment transport model in a Louisiana marsh and determine the short-term evolution of the tidal channels and the supply of sediments from the shelf; (3) integrate the short-term results of the high-resolution numerical model in already developed long-term models of tidal channel evolution; (4) link the transport of sediments to salt marshes via tidal channels to the resuspension of fine sediments in the adjacent shelf; (5) compare the results of the MURI project Mechanisms of Fluid Mud Interactions under Waves to measurements of sediment concentration in a nearby marsh channel; and (6) share and merge the model and results with those of the MURI Research Group. The study focuses on the Little Constance Bayou, a creek in the Rockefeller State Wildlife Refuge, to characterize the fluxes of sediments from the shelf to the marshes. The authors deployed a Nortek ADCP with an acoustic backscattering system at the mouth of the creek to measure tidal elevation, water velocity, and concentration of suspended sediment in time. A Sontek ADV was deployed in the bay in front of the channel mouth to record wave characteristics during the period studied.