Chapter 8: Wave Climate and Energy Dissipation near Santa Cruz Island, California

Nathan Burley & Robyn Suddeth

Offshore wave characteristics and nearshore transformation processes determine wave energy dissipation along coastlines. Wave impacts are a primary driver of coastal geomorphology, factoring into rates of cliff retreat and shoreline response. In this study the wave regime near Santa Cruz Island, California is presented and wave energy dissipation is calculated for different locations around the island. A model is used to estimate increased nearshore wave height and to verify breaking or reflecting wave conditions. Generalized refraction coefficients (KR) on W- NW swell and 10 m bathymetry is calculated. Energy dissipated on coastlines is modeled through reflected waves (in deep water) and breaking waves (in shallow water). The highest energy dissipation rates are on the northwestern corner of the island, confirming the significance of refraction effects. Southern shorelines experience lower energy dissipation due to high KR values, offshore sheltering by Santa Rosa Island, and a weaker southern swell. The results of this analysis are used in Chapter 9 to characterize patterns and rates and of coastal erosion of Santa Cruz Island.