Application of cost-benefit analysis for establishing coastal erosion setback buffer zones in South Korea

Setting up buffer zones to avoid coastal erosion is a method used worldwide, but not been widely adopted in South Korea. The economic feasibility of buffer zones raises questions. Using spatial cost-benefit analysis (CBA), this study compared setback acquisition costs with previously invested costs in hard protection and nourishment at two contrasting beaches: Gungchon-Munam Beach (in a rural area) and Haeundae Beach (in a highly developed urban area). Erosion zones by 2100 were predicted using MeePaSoL and HaeSaBeeN under the SSP2-4.5 and SSP5-8.5 sea-level rise scenarios. For Gungchon-Munam Beach, the results showed that the entire erosion-prone area can be acquired at a lower cost than past investments in hard infrastructure. By contrast, owing to high land and building values, Haeundae Beach allows only partial acquisition under equivalent costs. However, priority areas for setback buffer zones can still be identified. These findings suggest that setback strategies may be more economically viable in rural areas and selectively applicable in urban zones. This study proposes a replicable spatial CBA framework for determining effective setback areas, providing a decision-making tool for integrated coastal management. While the analysis focused on economic factors, the results highlight the need for future studies to incorporate ecological and social factors into the research. The proposed method supports precautionary coastal planning under climate change and can aid in long-term resilience by minimizing sunk costs and improving adaptive policy decisions. • Erosion zones by 2100 were predicted using the MeePaSoL and HaeSaBeeN models • Setback strategies can be more economically viable in rural areas • By contrast, setback strategies need to be selectively applicable in urban zones • A replicable spatial CBA framework to determine effective setback areas is proposed • This framework will be a decision-making tool for integrated coastal management