Estimating the Storm Protection Value of Coastal Dunes: A Geospatial Approach

Abstract

As of 2013, 133.2 million people lived in coastal shoreline counties, with population and development rapidly growing. This is not coincident with the increase in costly natural disasters, specifically from storm surge. There has been a point of emphasis in mitigating these destructive forces in recent years. Luckily, the natural habitat of healthy, sandy, vegetated dunes can mitigate storm damage. While dunes play a significant part in the way our shorelines function, their survivability is precarious, particularly on developed barrier islands where rising sea levels naturally force dunes landward. Developed shorelines restrict this process, confining dunes to a narrow strip of land and exposing them to increased wave activity and scarping. As communities determine the amount of investment necessary to protect or rebuild their dunes, understanding the value they provide to their community will be paramount when considering their coastal resilience strategies. This study focuses on Isle of Palms, South Carolina; a well-documented island on the South Carolina shoreline with a typical, but varied, beach/dune system. The Wave Height Analysis for Flood Insurance Studies (WHAFIS) model is used to estimate wave crest elevations along representative transects under several scenarios, particularly a current representative scenario and a without-dune scenario. The value of the dune incorporated differences in the scenarios with depth-damage functions that examined the relationships between water levels and building first-floor elevations. This model is the basis for creating a better understanding of the protective value of dunes in the region and highlights methodology techniques for replicability in other locations. The results of this study increase our understanding of dunes and their storm protection value as climate change and coastal development make scenario planning even more important in today's decision-making process.