LONGSHORE AND COASTAL CURRENTS AT SCRIPPS INSTITUTION PIER 
F, P. Shepard and D. B. Sayner 
University of California 
Scripps Institution of Oceanography, La Jolla, California 
ABSTRACT 
’ 
The relationship between currents inside and outside the breakers has 
been established by years of measurements at Scripps Institution pier. Veloc- 
ities in the outer surf zone are ordinarily several times those beyond the 
surf zone but there is little difference in the speed of currents just outside 
and those several hundred feet seaward of the breakers. The surf zone currents 
show some bias in favor of agreement in direction with those just outside but 
flow in the opposite direction is not uncommon. In general currents show an 
increased velocity with increase in breaker height. High winds have more 
effect on current velocity outside than inside the breakers. 
Introduction 
For five years the direction of currents have been observed at three 
points along the 1,000 foot pier at Scripps Institution as follows: (1) in- 
side the breakers, (2) just outside the breakers, and (3) at the end of the 
pier. For the past four years the observations have included measurements 
of velocity obtained by observing with a stop watch the time taken by a patch 
of dye in traversing the width of the pier. These measurements have been 
made on approximately 800 days. During these same years breaker height, wind 
velocity and direction, and general weather conditions have been recorded, 
In discussing the results of a large mass of observations of this type 
it should be remembered that they provide only a very incomplete picture of 
the general circulation of the area because they are limited to one line ex- 
tending less than 1,000 feet seaward. However, in conjunction with other 
studies on circulation patterns in the area (Shepard and Inman, 1950) they can 
serve some useful purpose and the comparisons of velocities inside and out- 
side the breakers are particularly informative. 
The study is somewhat strengthened by earlier records. Thus over a 
period of one year 210 observations of current directions inside and outside 
the breakers with 50 velocity measurements were obtained from Crystal pier at 
Mission Beach, six miles south of Scripps pier. Also a Dahl-Sverdrup current 
1 Contributions from the Scripps Institution of Oceanography, New Series No. 
This work represents results of research carried out for the Beach Erosion Board, 
Corps of Engineers, Department of the Army, under contract with the University 
of California. 
