Resilient Coastal Sites for Conservation in Hawai’i

Abstract

Hawaiian estuarine wetlands are characterized by swamps, salt- and mudflats, unique anchialine pools and historic fishponds. As sea levels rise, the Hawaiian Islands are particularly vulnerable and are already experiencing increased rates of inundation and record coastal flooding. The characteristics of some coastal wetlands make them more likely to adapt to sea-level rise and remain diverse and productive even as they adjust to climate-induced changes. In this project, TNC scientists mapped these characteristics and estimated the relative resilience of coastal sites on six Hawaiian Islands. Coastal sites were comprised, respectively, of tidal marsh, tidal flats and anchialine pools on the islands of Hawai’i, Kaua’i, Lana’i, Maui, Moloka’i and O’ahu.

For each site, the amount of migration space available under 20 sea-level-rise scenarios was estimated. The physical properties of the tidal marsh and tidal flat complexes were quantified, as was the amount of development potentially blocking migration of these habitats upslope as sea levels increase. While results are available for all 20 SLR scenarios, the final project maps are based on the 6.5-foot scenario because this scenario reveals the sites with the greatest long-term potential for adaptive response, and this scenario is a worst-case but plausible outcome by the end of the century.

The products of this study include:

• A report describing the methods used to evaluate sites and the results for each coastal shoreline region in the South Atlantic
• Downloadable datasets including results for additional sea-level-rise scenarios 
• To see how the migration space of resilient coastal sites was incorporated into the terrestrial Resilient & Connected Network (RCN), please visit the Resilient Land Mapping Tool.

Additional Resources

Downloadable datasets

Resilient Land Mapping Tool.

Citation

Barnett, A. and Anderson, M.G. (2022). Resilient Coastal Sites for Conservation in Hawai’i. The Nature Conservancy, Center for Resilient Conservation Science.