Transport of Placed Dredged Material in Surf and Nearshore Zone

Abstract

Driven by waves, water surface elevation, and wind conditions, a coupled wave, hydrodynamic, and sediment transport modeling system was developed to investigate the transport of placed dredged material in the surf and nearshore zones of southern Lake Michigan. With the measured bathymetric data and the implementation of a cross-shore transport routine, the modeling study focused on nearshore sediment migration, bed volume change, and subaqueous profile change due to wave action. The field datasets validated the model's capability in properly reproducing longshore and cross-shore current and wave processes that govern nearshore sediment transport. The analysis on survey data and simulation results indicates that time-averaged longshore current dominates the redistribution of sediment. Although the cross-shore transport is an order of magnitude smaller than the longshore transport, including the surf zone cross-shore process in the model contributes to net bed and subaqueous profile changes, and greatly improves the model performance.