GEOPHYSICAL VERIFICATION OF A NOVEL STRATIGRAPHIC MODEL, BOGUE INLET, NC, USA: COUPLED WITH HYDRODYNAMIC, SEDIMENTOLOGICAL, AND MICROFOSSIL DATA

Bogue Inlet is a micro-tidal inlet separating Bogue Banks and Bear Island, NC, USA. The coastline here is extremely dynamic as it is regularly exposed to hurricanes and extra-tropical cyclones and has a seasonally changing longshore drift. It is essential for coastal planning and adaptation to better understand and quantify the physical processes that drive change in this coastal system. This study tests the findings of Pearson et al. (2023), where a stratigraphic model of Bogue Inlet and its ebb-tidal delta was derived using DEMs from semiannual bathymetric surveys between 2005 and 2022. We verified their model using high-resolution geophysical data (CHIRP sub-bottom data) to compare with the modeled stratigraphy. Additionally, hydrodynamic modeling (Delft3d FM) is being used to understand sediment transport and the stratigraphy in the context of changing hydrodynamic conditions. Finally, sedimentological and micropaleontological (foraminiferal) data are being used to determine sediment transport directions and sediment sources. The CHIRP sub-bottom data show the presence of northeast-dipping sedimentary units and erosional surfaces that match the corresponding stratigraphic model outputs. These findings also align with our volumetric analysis (using ArcGIS) on the DEMs, where the ebb-tidal delta shows migration to the northeast. The presence of fossil foraminifera, with phosphorite-enriched tests present on the ebb-tidal delta shoal, suggests onshore transport from the Miocene Pungo River Formation, which crops out on the adjacent continental shelf of Onslow Bay. Associated sediment samples are undergoing grain-size statistical analyses to shed further light on sediment transport, and findings will be compared to the hydrodynamic models to capture the fluid dynamic and morphologic relationships.