Accession Number : ADA019512

Title :   Surf Observations and Longshore Current Prediction.

Descriptive Note : Technical memo.,


Personal Author(s) : Balsillie,James H.

Report Date : NOV 1975

Pagination or Media Count : 42

Abstract : Simultaneous field observations of breaker and current behavior have been made using techniques of the Littoral Environment Observation (LEO) program. This program, developed at CERC, is used to collect data on beach and surf conditions. The data base for this report represents a concentrated data collection effort over a period of 1 year at three beach sites at Point Mugu, California. Longshore current behavior is investigated in two ways: (a) Observed; and (b) predicted, using LEO data. Observed longshore currents are represented by the behavior of dye injected into the surf between the shoreline and breakers. Predicted longshore currents, based on the observation that longshore currents are generated primarily by waves, are estimated using a relationship for the average longshore current across the surf. The prediction model relies upon consideration of the radiation stress or wave thrust on water inside the breakers, and is evaluated using LEO breaker heights, angles of wave approach at breaking, and estimated widths of the surf zone. The degree of similarity between observed and predicted longshore currents is significantly high. This similarity not only suggests that the relationship for prediction of longshore currents is reasonable in field situtations, but that there is a surprising degree of internal consistency within typical LEO data sets.

Descriptors :   *Surf, *Ocean currents, *Coastal regions, Predictions, Dyes, Shores, Profiles, Geomorphology, Ocean waves, Height, Sand, Beaches, Circulation, Littoral drift, Mathematical models, Time series analysis, Sediment transport, Wind, Topography, California

Subject Categories : Physical and Dynamic Oceanography
      Civil Engineering

Distribution Statement : APPROVED FOR PUBLIC RELEASE