Evaluation of runup data allows presentation in a manner similar 

 to the conceptual sketch in Figure 7, using one form of relative depth, 

 dg/gT 2 . The presentation in Figure 7 is particularly useful for results 

 of tests in which a wide range of wave heights are used for each wave 

 period because the curves can be drawn with some degree of confidence. 



Data plotted as in Figure 7 can be further analyzed to derive lines 

 of constant dg/H^. For each dg/gT 2 line, values of H^/gT 2 corres- 

 ponding to specific dg/H^ values can be determined by 



%__ d s /CgT 2 ) 

 gT 2 " dg/H' 



Values of R/H^ at the appropriate H^/gT 2 value can then be deter- 

 mined. This analysis is shown in Figure 8 where lines of dg/H^ have 

 been superimposed on lines of d g /gT 2 (as shown in Fig. 7) . Analyses 

 show that even for high values of dg/H^ (i.e., 8.0, 15.0, 30.0, etc.) 

 the relative depth is important under certain conditions and accounts 

 for much of the scatter in some plots of earlier investigators. 



Figure 8 also leads to the reinterpretation of some previous runup 

 plots; e.g., Figure 9 shows the rubble-mound runup curves for various 

 slopes drawn as upper envelopes to the runup data. The right-hand parts 

 of the rubble-mound curves are essentially correct, lying in the region 

 where waves breaking on the structure slopes have little dependence on 

 dg/H^. The left-hand part of the curves (lower values of H^/gT 2 ), 

 however, tend to follow the runup values of the longest wave period 

 tested; a wave period longer than those tested would give higher R/H^ 

 values in the lower H^/gT 2 region. Lines of constant dg/H^ can be 

 defined for Figure 9, and do have negative or zero slopes similar to 

 the dg/H^ lines in Figure 8 or the smooth-slope lines in Figure 9. 



Furthermore, the dg/H^ curves are not necessarily straight lines 

 (on log-log graph paper). On steep structure slopes, with or without a 

 sloping beach, low values of dg/H^ tend to produce a straight line but 

 higher dg/FLj, values give a "plateaulike" effect in the approximate 

 range 0.001 < H^/gT 2 < 0.006. The lower limit tends to decrease with 

 high dg/FLJ, values. Figure 10 shows the trends for a steep structure 

 slope fronted by a sloping beach. 



The plateau area is attributable, apparently, to the combined 

 results of a change from breaking to nonbreaking waves, for decreasing 

 H^/gT 2 , and of a changing shoaling coefficient as the relative depth, 

 dg/gT 2 , progressively decreases. Flatter slopes, on which waves are 

 breaking for a wider range of H^/gT 2 , display less dependence of R/HJ, 

 on dg/H^ for H^/gT 2 > 0.001. 



30 



