Cordilleran Section - 113th Annual Meeting - 2017

Paper No. 39-3
Presentation Time: 2:15 PM


SUMMERS, Alisha Kay1, FLETCHER, Charles H.1, MCDONALD, Kristian1 and BARBEE, Matthew2, (1)Geology & Geophysics, SOEST, University of Hawaii at Manoa, 1680 East-West Rd, Honolulu, HI 96822, (2)Geology and Geophysics, University of Hawaii, 1680 East West Road, POST 721, Honolulu, HI 96822,

Protecting and preserving Hawaii’s beaches is important to the economy, ecosystem, and local island lifestyle. However, within the last century, beaches on Oʻahu have narrowed and in many cases vanished altogether. In response to federal incentives and locally significant erosion problems, the state of Hawai’i enacted a statewide Coastal Zone Management (CZM) program in 1977. As part of the policy framework reacted under the CZM Act, counties were given authority to regulate shorelines independently. Since then, the four counties have adopted different types of construction setback laws. Maui and Kauai have adopted rate-based setbacks, and Hawaii and C&C of Honolulu use a fixed distance of 20-60 ft depending on specific parcel conditions. Despite the establishment of these setbacks, shorelines continue to recede and beach to disappear. We present data from the east-facing shores of Oʻahu, that document changing shoreline positions and beach widths concurrent with coastal development. We reveal that historical seawall and revetment construction to protect eroding lands has caused a narrowing and loss of beach from 1928 to 2015 even while the CZM Act has been in force with laws at State and County levels specifically designed to protect the coastline.