Observation of the nearshore water circulation off a sand beach

Abstract

The nearshore circulation off a long sand beach at the southern end of Monterey Bay, California, was studied during February and March 1964. In preparation for the study, various types of floats were tested, and a resume of the advantages and disadvantages of each type in included as an appendix. Gathering the field data entailed the use of aircraft for aerial photography and an amphibious vehicle for launching and recovering the floats. The wind, wave, and tide conditions prevailing during all of the surveys were nearly the same. The circulation patterns found are presented in the form of schematic charts for each of the five surveys made. The dominant drift was observed to be directly onshore in the area seaward of the surf zone, but inside the surf zone the flow was to the north. Weak circulation cells were found to exist in the surf zone at varying locations along the beach. Current speeds are presented for the onshore drift, the dominant longshore current, the opposing feeder currents to rips, and the rip currents. The speed of the onshore drift was found to be greater that that of the opposing rip currents.