Author(s): Honghai Li

Linked Author(s): Honghai Li

Keywords: Coastal Processes; Nearshore Sediment Transport; Numerical Modeling; Nearshore Waves and Hydrodynamics; Longshore and Cross-shore

Abstract: Understanding and predicting the nearshore dispersion of the material by waves and currents greatly assist the coastal engineering practice. Numerical models have been widely used to simulate coastal sediment transport. But nearshore morphology evolution is still difficult to predict not only because it is complicated to properly represent cross-shore hydrodynamic and wave processes that govern sediment transport in shallow coastal area, but also the mechanism of sediment transport has not been well understood. In this study, a coupled coastal modeling system was developed to investigate the sediment transport in the nearshore zone of southern Lake Michigan. The model was driven by hydrodynamics, waves, and wind conditions and the model’s capability in simulating nearshore hydrodynamics and sediment transport was validated against measured data. With the implementation of a cross-shore transport module in the model, the study focused on the effect of coastal processes. By analyzing current and wave fields, sediment migration, bed volume change, and subaqueous profile change were examined in this lake coastal environment. The simulation results indicate that time-averaged longshore current dominates the redistribution of sediment in the shallow coastal area. Nearshore wave processes enhance sediment transport both in longshore and in cross-shore directions and are responsible for onshore sediment accumulation, nearshore bed volume, and vertical profile changes. Comparing the sediment transport rate in longshore with that in cross-shore direction, the former is approximately an order of magnitude greater than the latter. Although relatively small, the cross-shore transport process can play an important role in moving offshore sediment material towards the nearshore area and may have a positive impact on alleviating shoreline erosion.

DOI: https://doi.org/10.3850/IAHR-39WC252171192022768

Year: 2022