SYNOPTIC OBSERVATIONS OF SAND MOVEMENT

David B. Duane

Abstract


The U S Army Corps of Engineers' Coastal Engineering Research Center, in cooperation with the Atomic Energy Commission, initiated a multi-agency program to create a viable radioisotopic sand tracing (RIST) program Other agency participants in this program have been the Los Angeles District, Corps of Engineers, U S Air Force (First Strategic Aerospace Division), U S Navy (Pacific Missile Range), U S Army Mobility Equipment Command, National Aeronautics and Space Administration, and the State of California (Dept of Navigation and Ocean Development) CERC, together with the AEC's Oak Ridge National Laboratory has developed tagging procedures, hardware development, field surveys and data handling techniques that permit collection and analysis of over 12,000 bits of information per hour over a survey track of approximately 18,000 feet Data obtained with the RIST system can be considered as nearly synoptic observations of sediment transport m a single environmental zone or in adjacent beach, surf and offshore zones Using sand tagged with isotopes of gold, experiments have been carried out at several sites on the California coast Surf, Point Conception area, Point Mugu, and Oceanside Data from the studies carried out in beach areas unmodified by littoral barriers indicate that under a given set of wave conditions the alongshore velocity of sediment transport differs from zone to zone such that transport seaward of peakmg-breaking waves < transport on the beach face < transport in the plunge and surf zone Because of these differences, tracing surveys confined solely to the foreshore or offshore zones produce data only partially indicative of transport in the zone of immediate concern to coastal engineers.

Keywords


sediment transport; synoptic observations

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