EM 1110-2-1100 (Part V)
31 Jul 2003
Figure V-3-22. Dimensionless plot of nearshore breakwater projects For Y/ds versus Ls/Lg (from
Pope and Dean 1986)
Zyserman et al. (1998) used the Y/Yb ratio in their numerical model, process-oriented studies of
nearshore breakwaters. The distance Yb was taken as Y80, meaning the distance from shore where
80 percent of the undisturbed littoral transport takes place and, hence, a measure of the width of the
surf zone. Their research using a numerical model confirmed the empirical formulas of Dally and
Pope (1986) for tombolo and salient formation previously summarized.
(b) Planform configuration. Some research has provided insight into other variables that quantify the
planform shape of the shoreline as shown in Figure V-3-21. The length of the salient, Ys increased as the
Ls/Y ratio increased, as expected. Suh and Dalrymple (1987) developed an exponential expression involving
Lg YL2 , where Lg is the gap length for prediction of Ys, by combining movable-bed laboratory results and
s
prototype data. Rosati (1990) evaluated the relation and found it over-predicted Ys for the majority of
Shore Protection Projects
V-3-55
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