Mapping the coastal risk for the next century, including sea level rise and changes in the coastline: application to Charlestown RI, USA

A source–pathway-receptor method is used to assess the risk of the coastal community of Charlestown, RI, USA, to the 100-year storm, including effects of sea level rise (SLR) and shoreline/dune erosion. The 100-year storm is simulated using a chain of stochastic and physics-based models combined with a scenario-based approach. Storm surge and wave spectral parameters, obtained from the U.S. Army Corps of Engineers’ North Atlantic Coast Comprehensive Study (NACCS), are used as boundary conditions for high-resolution wave simulations, performed in the coastal and inundation zones using the steady-state spectral wave model STWAVE. Selected scenarios are defined to assess the magnitude of the variability in predicted damage resulting from the uncertainty in SLR, erosion rate, and time at which the 100-year storm would occur. Erosion rates are based on empirical analyses of historic rates of shoreline change, SLR measurements, and coastal erosion theory. The risk is measured in terms of damage to individual houses, based on damage curves developed in the U.S. Army Corps of Engineers, NACCS study. In addition, remediation scenarios are explored, demonstrating that a combination of dune replenishment and an increase in the residential resilience by elevating structures can significantly diminish the risk to the coastal community.