Ka‘a‘awa is located on the central east coast of Oʻahu. The beach is composed of calcareous sand and is lined with seawalls and homes located close to the shore. Shallow fringing reef protects the shoreline from the full energy of northeast tradewind waves and refracted north swells.
The beaches at Ka‘a‘awa have experienced low to moderate erosion rates (< -1 ft/yr). Even so, the presence of chronic erosion along a narrow, seawall-lined beach has resulted in loss of the beach at several locations over the past few decades. Areas of beach loss include Puʻu Mahie Point (transects 0-15), north of Swanzy Beach Park (transect 45), fronting Kamehameha Highway (76-85), and Makahonu Point (transects 146-180). Beach is now slowly accreting at Kalaeokaʻōʻio Point (transects 205-206). Waves wash to the base of seawalls in other sections at high tide and overwash Kamehameha Highway when the waves are large.
Previous studies (Hwang, 1981*; Sea Engineering, 1988**) also found long- term erosion of the vegetation line and water line along most of Ka‘a‘awa.
*Hwang, D. (1981) “Beach changes on Oʻahu as revealed by aerial photographs”, State of Hawaii, Department of Planning and Economic Development.
**Sea Engineering, Inc. (1988) “Oʻahu shoreline study”, City and County of Honolulu, Department of Land Utilization.
Last updated: July 2021
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