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SUMMARY

A simplified stochastic-process model involving statistical procedures is used to analyze sand tracer displacement data on an ocean beach. The procedures provide meaningful estimates of the direction and magnitude of the movement of beach sand through set intervals of time.

Results of a single tracer experiment are reported for a beach located near Virginia Beach, Virginia. Using a rectangular sampling grid, tracers were recovered at fixed times, then considered as items in a sample of X and Y displacements from the point of release. Comparison of the adjusted means of these samples on a time- stratified basis gave estimates of average particle velocity in two dynamic zones:

(1) swash zone: v̄(X) = 0.44 ft./min (0.22 cm/sec) longshore; (2) surf zone: v̄(Y)= 0.37 ft./min (0.19 cm/sec) offshore.

Using an estimate of the thickness of the mobile layer (the depth interval in which semi-continuous motion of beach sand occurs), a further estimate of the rate of longshore sand transport was computed at 440 yards3/day (336 m3/day).