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Title: Beach cycles in southern California
Authors: United States. Army. Office of the Chief of Engineers
Scripps Institution of Oceanography
Shepard, Francis P. (Francis Parker), 1897-1985
Keywords: Beaches
Southern California
Beach erosion
Beach morphology
Publisher: United States, Beach Erosion Board
Engineer Research and Development Center (U.S.)
Series/Report no.: Technical memorandum (United States. Beach Erosion Board) ; no. 20.
Description: Technical Memorandum
From the Introduction: The large waves accompanying winter storms cause a widespread denudation of southern California beaches. During the summer period of small waves the sand is brought back, completing an annual cycle. The beach berms vary in width with the seasonal changes so that in general they are widest at the end of the summer and narrowest at the end of the winter. Variation in berm width is also related to the spring and neap tides, the berms being the widest during the neap tides and the narrowest during the spring tides. This cutting back of the berms often results in scarp formation at the top of the foreshore, the scarps being mostly commonly developed in the fall during first period of large waves following the small waves of summer. In addition to the offshore-onshore movement of sand there are also important lateral shifts. The sand is shifted along the beach in the direction in which the waves are approaching. As a result of this lateral shift the northwest storms of the winter cause the southern end of some beaches to grow during the winter, and the southerly approach during the southern months moves the sand north and therefore produces a cut. Some partially protected beaches lack seasonal changes. Certain beaches have undergone long period changes which are non-cyclical; some of these changes are associated with engineering structures. All beaches must have a permanent loss of sand during the period of maximum cut. This loss from pocket beaches enclosed between headlands is believed to be very small since many of them have very meager sources of new sand. The more extensive open beaches, however, have a large loss of sand because of a net seasonal migration along the shore in the direction of the dominant wave approach or because sand is settling in submarine canyons. In general this loss is replenished by new sources of sand introduced by floods and cliff erosion.
This report first appeared in limited issue as Submarine Geology Report No. 11 of the Scripps Institution of Oceanography, Scripps Contribution No. 474, University of California
Rights: Approved for Public Release, Distribution is Unlimited
Appears in Collections:Technical Memorandum

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