was vertical for the plunging breaker. The slide of the runup was taken 

 as close to the time of maximum uprush as possible. The position of the 

 breaker was determined (from slides for 1970 and for 1971 through mid- 

 August) by knowing the location of fixed objects visible on the slide in 

 the immediate area of the breaker. Breaker type was also determined from 

 the slides. 



b. Visual Observations . Beginning in mid-August 1971, visual obser- 

 vations of the position and type of breaker and position of the wave uprush 

 were made and recorded at the time the wave envelope was recorded. The 

 position of the breaker could be estimated within 0.5 foot. These data 

 were recorded in the logbooks and on the visual observation forms (see App. 

 A for example forms) . 



c. Wave Gages. Attempts were made in 1972 to measure wave height in 

 the shoaling zone (including the breaker height) at 25-hour intervals using 

 wave gages. A specially adapted point gage for determining water surface 

 elevations (Sec. VI) was used to measure the vertical limits of runup, also 

 at 25-hour intervals. 



2. Analysis of Breaker Data . 



To analyze breaker characteristics, the type, height, and depth of 

 breakers are required. Breaker type can be determined from the slides 

 and from the visual observation forms. Galvin (1968) was used as a guide 

 for determining breaker type. Breaker depth can be determined from the 

 profile surveys knowing the breaker position. Breaker height data are 

 available only for 1972 and then only at 25-hour intervals. 



VIII. RIPPLE FORMATION DATA 



At the times of the special surveys (when the wave tanks were drained) , 

 35-millimeter slides of the ripple formations along the full length of the 

 profile were taken. Cloth, tapes and wood rules were placed on the beach 

 forming a grid with 2- by 3-foot sections. Vertical photos of the ripple 

 formations were taken from the top of the instrument carriage, with the 

 cloth tapes and rules just inside the frame of each exposure. The grid 

 assured a uniform area in each slide and the tape also provided a scale 

 for reducing the data. In the 6-foot tank, the size of each frame was 2 

 feet in the x-direction and 3 feet in the y-direction; in the 10-foot tank, 

 the size was 3 feet in the x-direction and 2 feet in the y-direction. 



IX. SAND SAMPLES 



1. Collection . 



Sand samples were collected by scraping 10 to 50 grams from the surface 

 of the bed when the tanks were drained after the special detailed surveys 

 of the beach profile. 



2. Size Analysis . 



The 1970 and 1971 samples were analyzed by the CERC Petrology Labora- 

 tory, using the Rapid Sediment Analyzer (RSA) . The U.S. Army Engineer 



42 



