A Holistic Framework for Evaluating Adaptation Approaches to Coastal Hazards and Sea Level Rise: A Case Study from Imperial Beach, California

Abstract

Sea level rise increases community risks from erosion, wave flooding, and tides. Current management typically protects existing development and infrastructure with coastal armoring. These practices ignore long-term impacts to public trust coastal recreation and natural ecosystems. This adaptation framework models physical responses to the public beach and private upland for each adaptation strategy over time, linking physical changes in widths to damages, economic costs, and benefits from beach recreation and nature using low-lying Imperial Beach, California, as a case study. Available coastal hazard models identified community vulnerabilities, and local risk communication engagement prioritized five adaptation approaches—armoring, nourishment, living shorelines, groins, and managed retreat. This framework innovates using replacement cost as a proxy for ecosystem services normally not valued and examines a managed retreat policy approach using a public buyout and rent-back option. Specific methods and economic values used in the analysis need more research and innovation, but the framework provides a scalable methodology to guide coastal adaptation planning everywhere. Case study results suggest that coastal armoring provides the least public benefits over time. Living shoreline approaches show greater public benefits, while managed retreat, implemented sooner, provides the best long-term adaptation strategy to protect community identity and public trust resources.

Managed retreat and planned retreat: a systematic literature review

“…A study of managed retreat policy frameworks in California reveals a framework for voluntary buyout and rent-back as an option to manage competing interests in coastlines, including public access, amenity and coastal ecosystems [134]. Siders & Keenan [135] provide an innovative quantitative analysis, again United States based, aimed at measuring the relationship between types of coastal adaptation measures relative to metrics of risk.…”

Editorial: Adaptation to Coastal Climate Change and Sea-Level Rise

“…Revell et al [23] presented a holistic framework for evaluating adaptation approaches to coastal hazards and SLR in a case study for Imperial Beach, California (USA). The article considers coastal flooding, erosion, and king tide flooding to develop a vulnerability assessment and compares five adaptation approaches-armoring, nourishment, living shorelines, groins, and managed retreat.…”

Managing retreat for sandy beach areas under sea level rise

“…There are three generic categories of SLR adaptation response: protect, accommodate, and retreat 10 , 11 . Protection is the defense and reinforcement of the shoreline to maintain existing land area 12 , 13 . Accommodation is a response where coastal risks are mitigated and coastal zones adapt by, for example, raising buildings 14 .…”