Spatio-Temporal Hydrodynamic Variability in a Tidal Channel

Abstract

The United States wetlands are rapidly deteriorating, resulting in heightened amounts of water contaminants, a threat to wildlife habitats, and erosion. A detailed understanding of hydrodynamics in tidal wetlands will enable the production of models for wetland change based on forecasted rises in sea level. This study uses data from a field experiment in a tidal wetland to quantify the spatio-temporal variability in near-bed velocities, TKE, and bed stresses as a function of tidal phase in a salt-marsh channel. ADCP, EMCM, OBS, and AWLS sensors were deployed at three locations in connected secondary and tertiary tidal channels of the St Jones River at the Delaware National Estuarine Research Reserve’s St. Jones located near Kitts Hummock, Delaware and Delaware Bay. Results show an asymmetric tidal cycle, resulting in asymmetric peaks in along stream, transverse, and vertical velocities as well as TKE, bed stress, and suspended sediment. Analytical methods to compute the forcing parameters within the tidal channels were also implemented, such as the Logarithmic Profile (LP), Covariance (COV), and the Turbulent Kinetic Energy (TKE) methods. The three-dimensional velocity profile is measured within each channel, showing the influence of each velocity component on channel hydrodynamics. Analysis of the aforementioned methods near the bed shows differences in the computed turbulent kinetic energy and bed stress.