Large‐scale responses of complex‐shaped coastlines to local shoreline stabilization and climate change

When modeling the large‐scale (> km) evolution of coastline morphology, the influence of natural forces is not the only consideration; ongoing direct human manipulations can substantially drive geomorphic change. In this paper, we couple a human component to a numerical model of large‐scale coastline evolution, incorporating beach “nourishment” (periodically placing sand on the beach, also called “beach replenishment” or “beach fill”). Beach nourishment is the most prevalent means humans employ to alter the natural shoreline system in our case study, the Carolina coastline. Beach nourishment can cause shorelines adjacent to those that are nourished to shift both seaward and landward. When we further consider how changes to storm behaviors could change wave climates, the magnitude of morphological change induced by beach nourishment can rival that expected from sea level rise and affect the coast as far as tens of kilometers away from the nourishment site. In some instances, nonlocal processes governing large‐scale cuspate‐cape coastline evolution may transmit the human morphological “signal” over surprisingly large (hundreds of kilometer) distances.