Fluorescent sand tracer was injected as a point source at the center of a circle having the diameter of 20 meters. After that, a number of core samples were taken at the sixteen points on the circle. At the same time, wave and current data were recorded by electro-magnetic current meter near the injection point. From the field observations based on this procedure, the following results are concluded.
1) The mean drift velocity of a snad particle on the direction of wave propagation is correlated with the skewness of velocity fluctuaion of wave motion.
2) The mean drift velocity of a sand particle on the direction of mean current is 1 to 2% of the mean current velocity.
3) The mixing depth of sand is nearly 8% of local wave height. It becomes, however, larger at the location where sand ripples exist.
4) Considerable vertical mixing takes place in the sea bed with the characteristic time scale of less than several minutes.
5) Two methods are presented to calculate the local sand transport rate using data obtained from proposed invesigation procedure.