beach length and the quantity accreted offshore amounted to 640 cubic 

 feet per foot (60 cubic meters per meter) beach length at depths of 

 -10 feet to -20 feet (-3 to -6 meters) below MSL. This comparison indi- 

 cates that there was a net gain of sand in the offshore area at North 

 Range which is offset by slight net loss of sand in the vicinity of 

 South Range and Indian Canyon Range. The net losses of sand at the two 

 southern range lines and gain at North Range may reflect a net northward 

 littoral transport caused by the high waves approaching from the south 

 on 8-11 January 1974. 



The volume of sand involved in the summer to winter profile trans- 

 ition was considerably less during the 1973-74 winter season than for 

 the previous year. This was especially noticeable at North Range where 

 the volume of sand eroded from the beach face in the 1973-74 winter 

 season was approximately one-third that removed during the winter of 

 1972-73. This difference in sand volume involved in the summer to winter 

 transition in beach profile configuration can be attributed to the rela- 

 tively mild winter of 1973-74. The difference between the volumes of 

 sand transported offshore during the two winter periods studied is also 

 apparent in Figures 6a, b, and c. The reference rod data show that sand 

 accretion occurred beyond a depth of -24 feet (-7.5 m) in the winter of 

 1972-75, but that accretion did not extend to depths of -24 feet (-7.3 m) 

 during the winter of 1973-74. The 1973-74 winter had relatively few 

 storms pass through the study area so that only occasional periods of 

 high waves affected the beach. 



This study employed the technique of Inman and Rusnak (1956) for 

 determining sand level changes on the shelf in order to accurately deter- 

 mine changes in beach profile configuration. Since these two studies 

 were done in the same general area, it is useful to compare their 

 results. Inman and Rusnak noted that the range of the sand level change 

 exceeded 2 feet (61 cm) at a depth of -18 feet, 0.29 feet (9 cm) at a 

 depth of -30 feet, and 0.16 feet (5 cm) at a depth of -50 feet, indicat- 

 ing a general decrease in the magnitude of sand level change with in- 

 crease in water depth. The range of sand level change of the three 

 range lines studied at Torrey Pines Beach was 4.1 feet (125 cm) at a 

 depth of -16 feet, 1.5 feet (45.7 cm) at a depth of -24 feet, 0.60 feet 

 (18 cm) at a depth of -33 feet, 0.20 feet (6 cm) at a depth of -45 feet, 

 and no change at a depth of -65 feet. These ranges of sand level change 

 and their decrease in magnitude with increasing depth follow similar 

 trends to those measured by Inman and Rusnak (1956) . However, the range 

 of the change was greater at Torrey Pines Beach for similar depths. This 

 may be related to the fact that the waves are somewhat higher at Torrey 

 Pines Beach than off Scripps Beach. It was noted in the earlier study 

 that the sand level was high in summer and low in winter at depths of 

 -18 to -30 feet. This trend was also observed at depths of -16 to -24 

 feet at Torrey Pines Beach. At Torrey Pines Beach high sand levels at 

 these depths occur in winter and spring (December to July) and low sand 

 levels occur in summer and fall (August to November) . The seasonal 

 fluctuation documented in the two separate studies are similar with any 

 differences probably being accounted for by variation in the wave char- 

 acteristics at the time of each study. 



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