Appendix C
Literature Review of Cross-
Shore Sediment Transport by
1
Rip Currents
Sediment transport by rip currents was represented in the shoreline change
modeling described in Chapter 6 of Volume I of this report. Sediment transport
by rip currents is a relatively unstudied coastal process. This appendix reviews
background material on rip currents.
Introduction
Rip currents are strong narrow currents that flow seaward through the surf
zone. These currents normally increase the longshore current velocity in the
dominant direction on the updrift side of the rip zone and decrease or reverse the
longshore current direction on the downdrift side (Shepard and Inman 1950). The
current strength and the distance that rip currents extend seaward are related to
the height of the incoming waves (Shepard, Emery, and LaFond 1941). Each
incident wave system forms a characteristic pattern of longshore and rip currents
(McKenzie 1958; Harris 1961, 1964). The result is a circulation cell in the
nearshore.
Rips are a major component of the surf zone circulation, and they are often
the dominant mechanism for offshore transport of water and sediment. Several
mechanisms have been proposed for the generation and spacing of rip current
cells. Quantification of the sediment transport enters the formulation of sediment
budgets and predictions of shoreline evolution. In the context of sediment
budgets and shoreline change modeling, several quantities are required to
estimate, in time and space, the volume of sand transported by rips. Rip currents
are not permanent features; they flow intermittently with fluctuations in velocity.
Most rip currents shift position along the beach, unless they are located adjacent
to jetties or headlands. A comprehensive description of a rip current system and
1
Written by Ty V. Wamsley, U.S. Army Engineer Research and Development Center, Coastal and
Hydraulics Laboratory, Vicksburg, MS.
C1
Appendix C
Literature Review of Cross-Shore Sediment Transport by Rip Currents
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