Assessing the morphodynamic response of a New England beach-barrier system to an artificial reef
Date of Original Version
As a result of climate change and the ensuing accelerating sea level rise, the Ninigret Trustom Pond beach barrier system, located along the southern shore of Rhode Island, USA, has become increasingly vulnerable to tropical storms, hurricanes, and Nor'easters affecting the region. In this work, we explore the ability of a segmented artificial reef (AR) to protect the Ninigret Trustom Pond beach barrier system, by reducing the incident wave energy and ultimately the beach erosion. A set of nine AR concepts are selected, which are predicted to be accretive based on Ranasinghe et al.’s (2010) design criterion (RVB), extended by van der Baan (2013) to apply to segmented submerged breakwaters. The effectiveness of each concept is then assessed through numerical simulations, for both average wave climate conditions and storm events, with and without sea level rise, using the 2D morphodynamic model XBeach. The AR concepts are evaluated based on their ability to reduce coastal erosion during the storm events, including with a near future sea level rise of 0.31 m (scenario based on local prediction by 2050 relative to 2020 following the intermediate NOAA scenario), while ensuring a slightly accretive behavior in average wave conditions. The reduction of the coastal erosion during the storm events is quantified by comparing the subaerial eroded volume at the site, with or without sea level rise, when implementing each of the nine pre-selected AR concepts. While all concepts are found to protect the shoreline during storm events, including with the 0.31 m sea level rise scenario, four of the nine AR concepts, pre-selected to be accretive based on the RVB criterion, are found to be erosive in average conditions. Assuming a given submergence level, the distance to the shoreline and the AR lateral confinement ratio, LC, (gap width to length ratio of the segments) are the main controlling parameter.
Publication Title, e.g., Journal
Schuh, Elin, Annette R. Grilli, Felix Groetsch, Stephan T. Grilli, Deborah Crowley, Isaac Ginis, and Peter Stempel. "Assessing the morphodynamic response of a New England beach-barrier system to an artificial reef." Coastal Engineering 184, (2023). doi: 10.1016/j.coastaleng.2023.104355.