Rip Current Spacing in Relation to Wave Energetics and Directional Spreading

Rip current spacings are compared with wave energetics and directional spreading in the Southern Monterey Bay. Southern Monterey Bay affords a unique environment to study rip currents owing to their prevalence created by near-normally incident waves on a sandy shoreline, It is hypothesized that rip current spacing is a function of wave directional spreading and energy flux, based on the morphodynamic modeling by Reniers et al. 2003. A gradient of wave energy flux exists due to headlands and refraction over Monterey Canyon. Rip currents are shown to occur between cusps in the shoreline, allowing cusp spacing to be a surrogate for rip spacing. Rip current spacing was inferred from beach morphology surveys, LIDAR imagery, and Argus cameras, and found to be O(150m) at Sand City and O(300m) at Marina, separated by 6km. Measured waves during a two month period using wave-rider buoys, show a gradient of across- shore energy flux between Sand City, F(sub x) =approximately 28000(J/m2), and Marina, F(sub x) =approximately 33000(J/m2). The two sites have the same peak directional spreading of energy value, sigma(peak) equals 14 deg, and slightly different bulk values for Sand City, sigma(bulk) equals 18 deg, and Marina, sigma(bulk) equals 20 deg. Therefore, the variations in rip current spacing could not be attributed to directional spreading, but appear related to variations in energy flux,Naval Postgraduate School Monterey CA is the author of 'Rip Current Spacing in Relation to Wave Energetics and Directional Spreading', published 2003 under ISBN 9781423501404 and ISBN 1423501403.