50 



under monochromatic waves may have contributed to increasing the variability 

 as they were gradually obliterated by repetitive motion of the survey wheels. 

 The standard deviation shown in Figure 2-6 is associated with an extreme pro- 

 file shape, and a large part of the variability was probably caused by cumula- 

 tive damage to the profile introduced by the repetitive survey. The error in a 

 single profile survey is expected to be less than that obtained in the repetitive 

 survey. 



Sediment sampling 



The origin of the sand from the Oregon coast and its emplacement in the 

 channel are described in Chapter 12. In addition, Chapter 12 also describes 

 bed density measurements that were made during the course of SUPERTANK 

 to determine if compaction occurred. 



Bed and suspended sediment samples were obtained by individual investi- 

 gators and as part of background data collection associated with the profile 

 change component of SUPERTANK. These samples were subsequently 

 analyzed independently at CERC, OSU, and the Florida Institute of Tech- 

 nology (FIT) for the geometric grain size diameter through mechanical 

 sieving. In addition, the hydraulic grain size diameter can be inferred through 

 particle fall-speed measurements conducted at FIT. 



Data Analysis 



Profile surveys 



After completion of data collection, the profile survey data were plotted 

 and visually examined by three people, including the first two authors, who 

 were involved with the majority of surveying operations at SUPERTANK. 

 Inspection of the individual profile plots and comparison of three-line surveys 

 revealed occasional small discrepancies as noise or obvious wheel floating. 

 These points were eliminated and replaced through nearest-neighbor interpola- 

 tion. Selected portions of the final profile survey data set have subsequently 

 been subjected to intensive analyses in independent studies, such as for bar 

 properties and net cross-shore sand transport rates, and the data have yielded 

 consistent and reasonable results. The profile data listed and plotted in 

 Appendix B of Volume II are the final cleaned values. 



Sediment 



At CERC, the mineralogy of a sediment sample taken from the surf zone 

 during SUPERTANK was determined through visual inspection by micro- 

 scope, as summarized in Table 2-1. The sediment consisted primarily of 

 quartz and feldspar. 



Chapter 2 Beach Profile Surveys and Sediment Sampling 



