Turbulent Structure and Sediment Transport Above Vortex Ripples in the Surf Zone

Abstract

Detailed observations of velocity profiles have been made within the surf zone above rippled and flat beds. These long-term observations were made from a fixed frame deployed on a shoal between two rip channels in Monterey Bay during RIPEX in spring 2001, and the more 2D local morphology during our measurements at Black's Beach during NOEX in the fall of 2003. The 1 cm vertical resolution, 3 component velocity profiles with co-incident suspended sediment concentration profiles provided by the Bistatic Coherent Velocity and Sediment Profiler allow sediment fluxes and velocity structure to be measured across the mean current and wave boundary layers. Examples of the net shoreward sediment flux seen in shoreward ripple migration under moderate to low forcing at the RIPEX shoal site will be contrasted with suspended sediment flux profiles during a significant accretion event near on yearday 309 at the NCEX site.