Hydrodynamic modeling and characterizing of Lagrangian flows in the West Scott Creek wetlands system, South Carolina

摘要

With increased recognition of the value of tidal wetlands and their defining hydrology, the need for better understanding of tidal flow and mixing characteristics is vital to any wetland restoration and enhancement projects and studies. A numerical modeling study was carried out to study the mixing and transport processes in the tide dominated West Scott Creek Estuary, South Carolina. The West Scott Creek estuary is a system of meandering tidal creeks and salt marsh between Edisto Island and the Edisto Beach barrier island. A coupled, depth-integrated hydrodynamic and particle transport model was developed. The model was calibrated and verified against a set of field-measured hydrodynamic data and the model-predicted water elevations, velocities and discharges were in good agreement with the field measurements. The hydrodynamically calibrated model was coupled with a particle tracking module to quantify the residence time distribution and associated transport mechanisms in a spatially varying situation. Computed residence time distribution, under tidal forcing, indicates a strong spatial variation and a non-monotonic distribution along the thalweg of the creek. The model computed a residence time of 4.92 days at the head of the creek. Numerical analysis of the Lagrangian flow field indicated varying mixing regions (strong and weak) within the wetland and the result is anticipated to provide useful information to assess the impact of coastal development in and around the West Scott Creek estuary including the restoration of tidal hydrology.