MIXED-SEDIMENT DYNAMICS AT A BACK-BARRIER BEACH NOURISHMENT

Abstract

Sand nourishments are increasingly applied to systems where the morphodynamics are driven by mixed hydrodynamic forcing (i.e., tides and waves) rather than by waves alone. Here, mixed-sand deposits are usually retrofitted to inadequate, hard flood defenses to act as a buffer against erosion and eventually failure of such infrastructure. Introducing different grain sizes into a system leads to more complex, differentiated sediment transport, as coarser fractions are mobilized under different conditions than finer fractions (McCarron et al., 2019). By focusing on a nourishment on the leeward side of a barrier island, we aim to find quantitative answers to the questions where, when and how the mixed-sediment composition changes and how that already is and will be expressed in the morphologic evolution of the area.