and Rusnak study was made on a shelf area between two branches of 



La Jolla Submarine Canyon so that sand movements were influenced by the 



refraction of waves over the complex nearshore bathymetry. This study 



of beach profile changes and onshore-offshore sand transport is similar to 



that of Inman and Rusnak (1956) but applied to a straight beach with 



uncomplicated offshore bathymetry. 



II. TORREY PINES BEACH STUDY AREA 



The site selected for this study was a segment of Torrey Pines Beach 

 in San Diego County, California. The study area consisted of a straight, 

 fine-grained sand beach located approximately 2 miles north of Scripps 

 Institution of Oceanography. A 1.6-mile (3.0 km) segment of this beach 

 that has gently sloping offshore bathymetry and is terminated shoreward 

 by a 300-foot (91 meters) high sea cliff was used for the beach profile 

 measurements (Figure 1) . This beach satisfied the basic requirements 

 for a straight beach with uncomplicated offshore bathymetry that is 

 exposed to waves from all offshore quadrants. In addition, the site has 

 the advantage of being readily accessible on land by a private road and 

 from sea by use of boat launching facilities at Scripps Institution. 



Torrey Pines Beach is at the southern end of a littoral cell that 

 extends northward 51 miles (82 km) to Dana Point. Sand is supplied to 

 this cell by streams entering the ocean along this stretch of coastline 

 and from minor sea cliff erosion (State of California, 1969) . Waves 

 cause a net longshore transport of sand to the south through the littoral 

 cell to Scripps Submarine Canyon which is located 1.5 miles (2.8 km) 

 south of the study site. Chamberlain (1960) and State of California 

 (1969) have estimated the net littoral transport in the vicinity of Torrey 

 Pines Beach at about 2.6 x 10 5 yd 3 /yr (2 x 10^ m^/yr) . Once in Scripps 

 Canyon, the sand is periodically transported by strong currents from the 

 nearshore zone through the canyon into deep water. 



The study site beach segment undergoes typical seasonal changes in 

 configuration due to changes in wave climate. During summer wave condi- 

 tions, the beach has a 100- to 200-foot-wide (30 to 60 m) backshore, a 

 relatively steep upper foreshore, and a pronounced berm. Winter storm 

 waves overtop the summer berm and erode the backshore, thus reducing 

 the width of the exposed beach. Winter beach profile configuration is 

 typified by a gently sloping beach foreshore that in places extends 

 shoreward to the toe of the sea cliff. Accurate measurement of these 

 seasonal changes in beach profile configuration was the principal 

 objective of this study. 



III. FIELD PROCEDURE 



1 . Bench Marks . 



The beach at the study site is oriented true north-south so that 

 three range lines were established normal to the beach in a true east- 



