Surf Observations and Longshore Current Prediction.
COASTAL ENGINEERING RESEARCH CENTER FORT BELVOIR VA
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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.
- Physical and Dynamic Oceanography
- Civil Engineering