Hydrodynamic and sediment observations across the sand-mud inner shelf near Ocean City Inlet
Abstract
Reliable sediment transport models are vital for environmental management and restoration, natural hazard mitigation, navigation, and industry. Poorly understood influences of cohesive and non-cohesive sediment mixtures limit the accuracy and precision of predictions. Subaqueous environments with combined wave-current hydrodynamic forcing and complex bathymetry-flow interactions give rise to additional modeling difficulties. We present the experimental design and results of a recent field campaign that explores cross-shore variation in bottom currents and turbulence throughout the benthic boundary layer to investigate sediment transport processes on a sand-mud shelf off of Ocean City, MD. Simultaneous observations were made of near bed hydrodynamic forcing from waves, tides, and currents, sediment composition, and the dynamics of small-scale bedforms. Analysis is focused on the methods for interpreting cross-shore variation in velocity profiles, turbulence and bed and suspended sediment mixtures across a shelf with ridges.
Instrumentation was deployed along a cross-shore transect for 45 days during the summer of 2019 that included four mooring locations to measure currents, waves, and turbulence (ADCP and ADVs), density, salinity, and temperature (CTDs and temperature sensors), bottom roughness (MBES), and concentration of suspended sediments (OBS) and sediments at the bed surface (conductivity array). Additional sediment stratigraphy data was obtained from sediment cores collected at three bi-weekly intervals. Bathymetric data of the transect was collected post instrument recovery. Velocity observations are used to estimate variations of turbulent kinetic energy (TKE), turbulent fluxes of momentum, and the bed shear stress throughout the observation period. Relating spatial and temporal variation in bathymetry and sand-mud concentrations to hydrodynamic forcings will improve our understanding of sediment transport in complex environments. Observations will also assist on-going efforts in developing high-fidelity physics-based numerical models for sediment transport of sand-mud mixtures.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMEP11E2100K
- Keywords:
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- 3020 Littoral processes;
- MARINE GEOLOGY AND GEOPHYSICS;
- 4315 Monitoring;
- forecasting;
- prediction;
- NATURAL HAZARDS;
- 4316 Physical modeling;
- NATURAL HAZARDS;
- 4217 Coastal processes;
- OCEANOGRAPHY: GENERAL