borrow is finer and more poorly sorted, and the fill factors and renour- 

 ishment factor for these data are shown in Figure 12. All four beach-fill 

 models are plotted against the standard reference axes for comparison pur- 

 poses; therefore, the pattern of the Dean ratios (Rp) is different than 

 in Figure 8. (Figure 8 is better for accuracy.) The points plot in the 

 first quadrant, and as expected for the overfill ratios, the adjusted SPM 

 value (R A = 2.80) lies between a high SPM (R s = 3.09) and a lower Dean 

 value (R^) = 2.12). The renourishment factor is 1.71 and is consistent with 

 the overfill values, showing the borrow to be less desirable for nourish- 

 ment than native sediments. 



The question to be asked now is which technique is best? Although any 

 of the fill factors might be best suited to some particular problem, the 

 adjusted SPM method is a compromise approach that clearly attempts to over- 

 come inadequacies of the SPM and Dean methods and thus it is generally 

 recommended. If the question is how much overage may be required, use the 

 adjusted SPM method (R^) whereas the renourishment factor (Rt) should be 

 applied to attempt to answer how often renourishment may be required. 

 Appendix B contains an example of using both methods for evaluating a prob- 

 lem where beach fill is required. 



Most engineers have been familiar with only the fill factor-type ap- 

 proach to solving beach-fill problems. However, the renourishment approach 

 is probably better suited to those common situations where beach erosion 

 is a continuing process that must be considered in any plans for long-term 

 shore protection. Undoubtedly, the use and popularity of the renourishment 

 approach will increase as data accumulate from field experiments and from 

 monitoring the performance of nourished projects. 



V. CONCLUSION 



This study considers the current "state-of-the-art" with regard to two 

 topics. The first is to show the importance of composite gsd for charac- 

 terizing native beach and borrow site sediments, and the uses of composites 

 for beach-fill evaluation. The second topic is to set up general sampling 

 and computational guidelines to ensure that composites accurately repre- 

 sent the characteristics of the sedimentary bodies sampled. Other topics, 

 such as describing beach-fill models and sediment properties, have also 

 been included to provide a framework for considering the major subjects. 

 Several important topics have not been considered here because they can be 

 found elsewhere; e.g., James' (1975) discussion of the uses and interpre- 

 tations of the renourishment and fill factors. Topics involving unsolved 

 problems or for which adequate data are unavailable were also omitted. A 

 great number of these subjects deserve attention, and the fact that they 

 are so numerou c attests to the dynamic and changing nature of the broad 

 subject of beach fill. Topics that are in particular need of further 

 thought and investigation are the practical, economic, and responsibility 

 aspects of beach fill. These topics were chosen arbitrarily for organiza- 

 tional purposes but each contains a number of elements (often common ele- 

 ments) that are mentioned, in part, in the concluding paragraphs. 



38 



