The fall speed of surf zone sediment samples was measured in a settling 

 tube. Figure 2-7 gives a representative result, in which the particle fall-speed 

 distribution is plotted for five samples. The predominant peak occurs at 

 3.3 cm/sec. 



Summary 



A survey system consisting of an auto-tracking Geodimeter, manually 

 moved carriage, and previously developed software was implemented at 

 SUPERTANK to provide rapid surveys while preserving accuracy and 

 resolution of major features of the beach profile. The system and associated 

 operation procedure were shown to be accurate with error less than 0.3 cm in 

 most areas of the profile exposed to wave action. Additionally, the survey 

 system provided an integrated means of measuring instrument location inside 

 and outside the channel. The large number of beach profile surveys made in 

 conjunction with hydrodynamic and other measurements provides a reliable 

 database for a wide range of profile change configurations with which to study 

 cross-shore hydrodynamic and sediment transport processes. 



The beach sediment, consisting primarily of very uniform fine-grained 

 quartz and feldspar sand, was analyzed to have a median diameter of 0.22 mm 

 and a fall speed of 3.3 cm/sec. 



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0.647 0.876 1.173 1.552 2.025 2.607 3.316 4.163 5.168 6.343 7.710 



Fall Speed (cm/sec) 



■ Sample 1 H Sample 2 H Sample 3 13 Sample 4 □ Sample 5 



Figure 2- 

 52 



7. Fall-speed distribution of SUPERTANK surf zone sediment 



Chapter 2 Beach Profile Surveys and Sediment Sampling 



