Morphological Evolution of a Nearshore Nourishment Constructed of Dredged Sediment in Southern Lake Michigan

Abstract In 2024, 49,683 m 3 of sediment was dredged from Burns Small Boat Harbor, Indiana, and placed in the adjacent nearshore in two mounds. The beneficial use of dredged sediment from navigation channels through nearshore nourishment is a common technique to cost-effectively add or retain sediment within the littoral system, particularly for sediment that is predominately sand but contains nontrivial quantities of silts or clays. This supports coastal resiliency, but sufficiently large quantities of fine-grained sediment can also generate turbidity plumes. Elevation, aerial and terrestrial imagery, hydrodynamic, sediment grain size, and turbidity data were collected before, during, and after nearshore nourishment construction to quantify erosion reduction benefits and monitor and quantify potential turbidity increases. Both mounds deflated significantly in the first 5 months after construction, with the western mound volume decreasing by 73% and the eastern mound volume decreasing by 63%. Mound positions were quite stable during the same time frame with the centroid for each mound moving