were small and considered not worth the construction effort. Therefore, the 
curve for the 30° tests was deleted and a straight training wall was used. 
3. Sand-Moving System. 
As the waves approached the beach at an angle, the sand moved in the 
downdrift directione Most of it deposited in the sand trape The sand which 
escaped the trap deposited either on the downdrift concrete apron or beyond 
the apron and rubble (covered to keep sand from being lost within it) onto the 
basin floor. This area is shown in Figure 2 as the supplementary deposition 
area. Although separate measurements of the sand deposited in each area were 
not taken, it is estimated that 80 to 95 percent of the longshore transport 
fell into the trap. The greater the transport rate and the suspended sedi- 
ment, the greater was the amount of sand escaping the sand trap. 
The trap was cleaned continually during a test using an eductor attached 
to a small centrifugal pump. Water was pumped through the eductor at high 
speed, creating a suction to pick up the sand (Fig. 8). The sand was pumped 
to the weighing station (Fig. 9), deposited in one of two bins, and weighed 
submerged. When divided by the appropriate time period, the value became the 
immersed weight longshore transport rate. 
After the weighing, the sand was pumped, using another eductor, into a 
sand feeder. The sand feeder is a vertical cylinder open at both ends in 
which sand is introduced through the top and removed by waves through the 
bottom. A diagram and a photo of the feeder are given in Figures 10 and ll. 
The primary advantage of the feeder is that it permits waves to control the 
amount of sand introduced onto the beach. Savage (1961) discusses the feeder 
and its development. 
In summary, the complete sand-moving system (Fig- 12) included the 
following: 
(a) A sand trap, a downdrift concrete apron, and a downdrift 
deposition area which trapped the sand; 
(b) a downdrift eductor-pump combination which moved the trapped 
sand to the weighing station; 
(c) a weighing station which weighed the amount of sand moved; 
(d) an updrift eductor-pump combination which moved the sand from 
the weighing station to the sand feeder; and 
(e) a sand feeder which redeposited the sand onto the beach. 
4. Instruments. 
Wave heights were measured using parallel-wire wave gages (see Fig. 7). 
Gages 1 and 2, located seaward of the toe of the beach, were used for all 15 
tests. Gage 3, located over the beach, was used for tests 5 to 15. Gage 4A, 
located close to the breaker line, was used for tests 5 to 1l. Beginning with 
test 12 for the remainder of the tests, gage 4A was adjusted to measure the 
breaker height and then renamed gage 4B. 
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