Tradeoffs between beach nourishment and managed retreat: Insights from dynamic programming for climate adaptation decisions

• Published in: Environmental modelling & software : with environment data news Vol. 125; no. C; p. 104603
• Main Authors: Cutler, Emma M., Albert, Mary R., White, Kathleen D.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.03.2020; Elsevier Science Ltd; Elsevier
• Subjects: Adaptation; Beach nourishment; Beaches; Climate adaptation; Climate change; Climate change adaptation; Climate models; Coastal management; Coastal zone management; Coasts; Community planning; Damage; Decision making; Decision theory; Dynamic programming; Economic analysis; Economic models; Flood predictions; Flooding; Hazardous areas; Managed retreat; Offsets; Property values; Real estate; Risk management; Risk reduction; Sea level; Sea level rise; Beach nourishment; Sea level rise; Dynamic programming; Coastal management; Managed retreat; Climate change adaptation
• ISSN: 1364-8152; 1873-6726
• DOI: 10.1016/j.envsoft.2019.104603

Coastlines are vulnerable to sea level rise, erosion, and flooding, all predicted to worsen as climate change continues. Models are needed that incorporate dynamic processes within coupled economic and physical systems for decision-makers, including when to retreat from hazardous areas. This paper presents a coupled geo-economic model of beach width and property value with exogenous sea level rise. Discrete dynamic programming identifies optimal beach nourishment and managed retreat strategies. As a new contribution, we treat expected damages as costs, which demonstrates that increased damage offsets some benefits of development along hazardous coastlines. The model identifies managed retreat as preferable to beach nourishment when damages exceed a threshold. Regret associated with retreat depends on sea level rise damages and the timeframe of analysis. Considering dynamic complexity of coastal systems, as this model does, may produce climate adaptation plans that better address community needs and reduce risk over timescales of interest. [Display omitted] •Treating damages as costs removes perverse incentives to develop hazardous coasts.•Relocation becomes optimal when the proportion of value damaged exceeds a threshold.•Optimal decisions are sensitive to the value of vulnerable assets.•Waiting too long to retreat could be more costly than retreating too soon.