Assessing the role of the North Carolina outer banks as a nature-based feature in reducing coastal flood damages

Abstract

Barrier islands are increasingly recognized as vital natural infrastructure for mitigating coastal flood risks, yet their economic protective value remains challenging to quantify. This study investigates the hydrodynamic and economic impacts of North Carolina’s Outer Banks by simulating six synthetic tropical cyclones representing 0.2%, 1%, and 4% annual exceedance probability (AEP) flood events across four barrier island configurations using the coupled ADCIRC+SWAN model. Changes in maximum water surface elevation (WSE) were assessed at key coastal and estuarine locations, and resulting flood extents were translated into economic losses using FEMA’s HAZUS 6.1 platform. The results show that the Outer Banks barrier islands provide storm-surge protection by limiting increases in mainland WSE within estuarine and riverine systems. Compared with the base case, island-removal scenarios produced approximately 39–47% higher mean total property losses and 30–40% higher displaced population. To support hazard mitigation and resource allocation, a screening-level regression analysis was used to summarize the influence of storm characteristics and barrier-island configurations on economic losses and to compare the relative protective benefits of northern and southern island groups. This integrated framework provides a repeatable approach for linking physical and economic assessments to inform coastal planning, prioritization, and investment in nature-based solutions for flood risk reduction.

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