Field Observations of Surf Zone-Inner Shelf Exchange on a Rip-Channeled Beach

Field Observations of Surf Zone-Inner Shelf Exchange on a Rip-Channeled Beach

Brown, J.A.
MacMahan, J.H.
Reniers, A.J.H.M.
Thornton, E.B.

Civil Engineering and Geosciences

Hydraulic Engineering

2015-06-05

Cross-shore exchange between the surf zone and the inner shelf is investigated using Lagrangian and Eulerian field measurements of rip current flows on a rip-channeled beach in Sand City, California. Surface drifters released on the inner shelf during weak wind conditions moved seaward due to rip current pulses and then returned shoreward in an arcing pattern, reentering the surf zone over shoals. The cross-shore velocities of the seaward- and shoreward-moving drifters were approximately equal in magnitude and decreased as a function of distance offshore. The drifters carried seaward by the rip current had maximum cross-shore velocities as they exited the surf zone and then decelerated as they moved offshore. The drifters moving shoreward accelerated as they approached the surfzone boundary with maximum cross-shore velocities as they reentered the surf zone over shoals. It was found that Stokes drift was not solely responsible for the onshore transport across the surfzone boundary. The cross-shore diffusivity on the inner shelf was greatest during observations of locally contained cross-shore exchange. These field observations provide evidence that the cross-shore exchange between the surf zone and inner shelf on a rip-channeled beach is due to wave-driven rip current circulations and results in surface material being contained within the nearshore region.

circulation/dynamics
currents
Lagrangian circulation/transport

http://resolver.tudelft.nl/uuid:1ca82668-4f72-4894-b6dd-7b45e0fac841

American Meteorological Society

2015-12-05

0022-3670

https://doi.org/10.1175/JPO-D-14-0118.1

Journal of Physical Oceanography, 45 (9), 2015

Institutional Repository

journal article

(c) 2015 American Meteorological Society