Jordan M. Slott

Synergies between Adjacent Beach-Nourishing Communities in a Morpho-Economic Coupled Coastline Model

Beach “nourishment” consists of placing sand on an eroding beach. The widened beach provides increased storm protection to adjacent structures and improved recreational benefits, but is most often transient, requiring on-going, repeated nourishment episodes. Numerical models of beach nourishment typically address such questions as how long a widened beach will last; economic models compare the benefits and costs of preserving a stretch of beach without regard to its geomorphic evolution. Neither have addressed the physical nor economic interactions between adjacent nourishing communities. Here, we couple a numerical model of coastline evolution and a cost-benefit model of beach nourishment, allowing adjacent communities to make dynamic nourishment decisions. Beach nourishment benefits adjacent communities both “updrift” and “downdrift.” The total amount of money spent on nourishment activities can decrease by as much as 25% when adjacent communities both conduct on-going nourishment projects, as opposed to the case where each community nourishes in isolation.

LARGE-SCALE, COMPLEX-SHAPED COASTLINE RESPONSES TO DIFFERENT FORMS OF LOCAL SHORELINE STABILIZATION AND CLIMATE CHANGE

This exploratory work suggests that even isolated, localized human manipulations of the coastline system, when maintained over decadal or longer timescales, can significantly affect the large-scale evolution of a complex-shaped coastline, especially in the context changing storm climates. Here, we build on an earlier study that examined the large-scale effects of localized beach nourishment, finding that localized stabilization through seawalls can increase shoreline change rates by up to meters per year within tens of kilometers of the site of the stabilization.