McPherran, Kaitlyn Ann2024-01-242024-01-242023https://udspace.udel.edu/handle/19716/33894Sandy barriers and tidal inlets are dynamic coastal systems whose behavior is the result of complex interactions between existing and antecedent geology and morphology, hydrodynamics, and anthropogenic intervention on a variety of spatial and temporal scales. Humans have always and will continue to live, work, and recreate on the coast, and therefore, understanding the forcing mechanisms of coastal change on a variety of scales is critical to protecting natural resources as well as human life and infrastructure. This dissertation aimed to fill knowledge gaps in the understanding of sandy barrier and tidal inlet hydrodynamics and geomorphology on event to decadal time scales within the Chincoteague-Assateague-Wallops (CAW) inlet and barrier coastal system on the Eastern Shore of Virginia, USA. ☐ During the course of the study, the small-scale hydrodynamic and geomorphologic effects of six Atlantic tropical storm events were captured by moored hydrodynamic instruments. During storm events, waves and currents flow into Chincoteague Inlet, likely increasing coastal flooding and storm damage to the residents and infrastructure of southern Chincoteague Island. The flow of waves and currents into the inlet during storm events also causes net sediment transport into the inlet in the form of bedload and suspended sediment. Frequently after tropical storm events, a pulse of less saline water flushes out of Chincoteague Bay via Chincoteague Inlet, dampening wave and tidal current transport within the inlet for up to seven days post-storm. This dampening effect slows the post-storm recovery of the inlet ripple field. Finally, these freshwater pulse events are likely an important forcing mechanism to return sediment stored in Chincoteague Inlet and Chincoteague Bay back to the alongshore transport system. ☐ Analyses of hydrodynamics and geomorphology on seasonal to annual time scales focused on trends in wave climate, shoreline change, nearshore and onshore feature formation and migration. Seasonal peak wave direction results suggest that, at Chincoteague Inlet, which is sheltered from northerly waves by Assateague Island, waves primarily come from a southerly direction for much of the year, and due to the north-south orientation of Chincoteague Inlet, this increases the risk of flooding on Chincoteague Island, which is already a problem for Chincoteague residents. ☐ Finally, the interannual to decadal trends in shoreline change, inlet channel migration, beach ridge development, and wave climate were investigated in the CAW system in order to more fully understand the recent interannual to decadal history and development of this dynamic spit and inlet system. During the 1980’s and 1990’s, the western spit of Fishing Point (the spit hook at the southern end of Assateague Island) grew rapidly across Chincoteague Inlet, forcing the inlet channel to migrate WNW towards Wallops Island and eventually fragment into the southwestern and northeastern channel sections present today. The rapid growth of the western spit of Fishing Point led to a movement of the depocenter from the western spit to the southern tip of Fishing Point circa 2000. The southern tip began to sequester much of the sediment that had previously been feeding the western spit, leading to the near-complete erosion of the western spit and the rapid accretion of the southern tip. Results of the analysis of shoreline change as related to wave climate suggest that shoreline changes on interannual to decadal timescales are driven largely by fair-weather wave climate, with additional inputs from storm-related transport.Coastal geologyHydrodynamicsCoastal systemsChincoteague-Assateague-WallopsThesis1445845907https://doi.org/10.58088/ecwq-ad512024-01-22en