An agent-based model for community flood adaptation under uncertain sea-level rise

Adaptation has become the major approach to reduce the adverse effects of storm surge and sea-level rise. However, maladaptation can happen when adaptation actions unintentionally increase community vulnerability. To evaluate the adequacy and efficacy of adaptation policies under uncertain sea-level rise, this study presents an agent-based model by integrating the random nature of storm surges, private adaptation decisions, and real estate market valuation. We evaluated the evolving flood damage of different adaptation strategies under two bounding cases of real estate market change. Our model results quantitatively illustrate the accelerating damages of storm surges under climate-induced sea-level rise. A reform in flood insurance to risk-based rates with a means-tested voucher program and a government-subsidized “twice and out” buyout program could both substantially improve coastal resilience. However, community adaptation with a public seawall may deliver false risk perception to high-risk property owners and result in maladaptation when sea-level rise rate is high. The modeling approach developed in this study can be used as a policy analysis tool to measure the impacts of sea-level rise and the effectiveness of adaptation strategies in coastal communities.