Mapping Erosion Hazard Areas on the Island of Kauaʻi
The beaches of the Hawaiian Islands attract nearly 9 million visitors each year, who inject around $15.6 billion into the state’s economy and support almost 200,000 jobs. Beyond their economic importance, Hawaiian beaches are also culturally and ecologically valuable. However, sea-level rise is causing many beaches to disappear, endangering property, infrastructure, and critical habitats.
WHAT: Although healthy beaches often temporarily gain and lose sand, sea-level rise is resulting in chronic erosion on many Hawaiian beaches. On the island of Kauaʻi, approximately 73% of sandy shorelines are currently retreating inland. Beach loss negatively impacts rare and endangered species and exposes coastal development to higher risk of damage or loss due to inundation, further erosion, or storms. Researchers modeled beach response to rising sea level over the next century to generate data and maps of erosion hazard areas on Kauaʻi.
FINDINGS: Coastal erosion is expected to significantly increase on Kauaʻi, doubling its historic rate by 2050 and leading to partial or total loss of 90% of beaches by 2100. The interactive maps produced through this research provide local-scale information about which areas of coastline are especially vulnerable to future erosion as a result of sea-level rise.
SIGNIFICANCE: The Hawaiʻi Department of Land and Natural Resources, local planning departments, and other coastal management agencies are using this project’s data and maps for hazard preparedness and adaptation planning on state and local scales. Results were incorporated into a statewide study of shoreline sea-level rise vulnerability led by the Hawaiʻi State Interagency Climate Adaptation Committee.
While this study focused on Kauaʻi, it established a methodology for predicting future beach erosion that is now being applied to other areas of the state to improve coastal management decision making.