Model Scenerios of Shoreline Change at Kaanapali Beach, Maui, Hawaii: Seasonal and Extreme Events

Kaanapali beach is a well-defined littoral cell of carbonate sand extending 2 km south from Black Rock (a basalt headland) to Hanakao’o Point. The beach experiences dynamic seasonal shoreline change forced by longshore transport from two dominant swell regimes. In summer, south swells (Hs = 1-2 m Tp = 14-25 s) drive sand to the north, while in winter, north swells (Hs = 5-8 m Tp = 14-20 s) drive sand to the south where it accumulates on a submerged fossil reef. The Delft3D modeling system accurately predicts directly observed tidal currents and wave heights around West Maui, and is applied to simulate shoreline change. Morphologic simulations qualitatively resolve the observed seasonal behavior.