DETECTING BEACH NOURISHMENT SIGNALS IN MODERN SPIT MORPHOLOGY USING A COUPLED MAPPING AND MODELING APPROACH AT SANDY HOOK, NEW JERSEY

Considering that morphological features (i.e. height and spacing) of relict and active foredune ridge complexes are sensitive to both sediment supply volume and temporal delivery, we infer that a simple cross-shore geomorphic model of ridge and swale development can quantify individual sediment budget contributions to short-term shoreline processes. Previous work has used such a model to correctly emulate ridge structures observed in time series analysis along one section of a prograding barrier-spit. Sandy Hook, located at the mouth of Lower New York Bay, in New Jersey is a terminal depocenter for sand transported north along the Central Jersey coast. The spit has grown extensively over the past three hundred years with shoreline advancement to the North and the West. This development is periodic, the most recent stage encompassing approximately from 1920 through the modern day. Such timing suggests that while historical growth of Sandy Hook is responsive to natural alterations to the sediment budget, human changes (i.e. beach nourishment) to the sediment budget account for much of the magnitude producing recent shoreline features. Quantifying this impact requires expanding the previous model application in order to trace nourishment episodes through the entire spit system. Having delineated the starting shoreline from historical aerial photographs LiDAR-derived topography is used to calculate subaerial sediment volumes added post-1920 along multiple transects. We construct time series analyses from this information that represent the morphological development of Sandy Hook as a whole and compare them to outputs from our model. Ultimately, with input fluxes clearly defined, performing sensitivity analysis allows us to possibly detect signals from beach nourishment events and explore the impact of beach nourishment programs. All with-an-eye-towards understanding future changes that may result from increasing rate of sea level rise and other anthropogenic forcing.