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ORE Seminar: Waikīkī Beach Improvement Project - Kaimana Coastal Consultants

Xinyi Zhang, Maliheh Gholizadehsarvandi, Kaja Reinhardt, Scott Hellinger (ORE Capstone Class) Abstract Waikīkī Beach is experiencing chronic erosion due to disrupted natural sand transport, shallow reef channels, and accelerating sea-level rise. The shoreline between the Fort DeRussy and Royal Hawaiian groins has become increasingly vulnerable, with frequent overwash posing risks to public safety and adjacent properties. This project aims to implement a beach nourishment and long-term maintenance plan for Waikīkī, supported by the design of a low-crested reef-crest breakwater system intended to reduce wave energy, stabilize the nourished shoreline, and enhance long-term coastal resilience. Offshore wave conditions were established using 32 years of hindcast data and 200 years of synthetic hurricane simulations to define both operational and extreme design scenarios. XBeach modeling was utilized to evaluate wave patterns, nearshore circulation, and structural performance under multiple design alternatives. Comparative simulations showed that a shoreline-parallel alignment reduces hydrodynamic disturbance and achieves up to a 70% decrease in significant wave height within the protected area. The modeling and metocean analysis guided the development of the structure’s geometry, armor sizing, and material specifications. A comprehensive constructability assessment was also performed, including barge selection, crane operations, seasonal metocean windows, and construction-related risks. Environmental considerations—such as turbidity control, eDNA monitoring, and coral reef protection—were incorporated to support future permitting requirements. An engineering economic evaluation ensures that the proposed solution remains cost-effective while achieving its intended performance. Overall, the project presents a technically robust, environmentally responsible, and operationally feasible approach to improving coastal resilience and sustaining the recreational and cultural value of Waikīkī Beach. Zoom Meeting ID: 890 6867 4318 Passcode: ORE

Event Sponsor
Ocean and Resources Engineering, Mānoa Campus

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