in the model test set-up in an effort to simulate, at least qualita- 

 tively, the natural (prototype) regime wherein the measurements in 

 question may have occurred. 



Figure 5 stiows experimental curves of wave set-up versus 

 wave height and distance from the shoreline. These curves show, for 

 the two water levels tested (1.75 and 8 feet MSL) , that at a selected 

 depth and distance from the shore there is, in general, an increase of 

 wave set-up with increase of wave height, and that for a constant wave 

 height in deep water (90 feet in the model), there is, in general, an 

 increase of wave set-up toward the shore. These wave set-up results 

 have been found for one value of the near shore beach slope only (1 on 

 32) and also for only one bottom material, smooth concrete. Other 

 tests in the Beach Erosion Board laboratory have shown that for con- 

 siderably steeper beach slopes (1 on 3 and 1 on 6) and waves of some- 

 what lesser height (2 to 4 feet), there is no wave set-up but rather 

 there is wave set-down. It would apoear from the diversity of these 

 two indications, probably extremes, that the effect of slope on wave 

 set-up may be quite large. It is presently contemplated that further 

 generalized study of wave set-up will be made in the near future. One 

 objective of such additional study would be to determine the effect of 

 beach slope. 



The maximum values of wave set-up for the initial five to ten 

 waves generated, not to be confused with the stabilized maximum values, 

 have been tabulated in Table 2 for two stations only. Values have been 

 tabulated at one station for each water level. These stations were 

 200 feet seaward of the MHW line for the ordinary storm water level 

 (1.75 feet MSL) and 375 feet landward of the MHIV line and in the pool 

 area for the hurricane storm water level (8 feet MSL). The maximum 

 value of wave set-up measured for a stabilized condition of wave action 

 (after 5 to 10 minutes running time) was 3 feet. This value was obtained 

 in the pool area landward of the berm crest. The test conditions for 

 this measurement were: wave height 30 feet, wave period 15 seconds, depth 

 20 feet, and a hurricane storm water level of 8 feet MSL. Smaller values 

 of wave set-up were measured for wave and water level conditions below 

 the maxitaum and the wave set-up values for these and the maximum value 

 are all given in Table 2. From this information on the model test results, 

 it appears reasonable to predict stabilized wave set-up values up to 3 feet 

 for the maximum wave and water level conditions tested. 



As seen from Table 2 the initial values of wave set-up exceed con- 

 siderably the stabilized values; it is, therefore, emphasized that these 

 values existed only temporarily, that is for the first five or so waves 

 generated. For all practical purposes, this phenomenon iias no real 

 counterpart in nature, since ordinarily, and also for storm conditions, 

 there is a gradual build-up of wave intensity at the coast and not the 

 sudden onshore rush of water from maximum wave conditions as was observed 

 in the model tests. This information was included mainly as a matter 

 of general interest to show the magnitude of wave set-up for the initial 

 waves as experienced in the model. It is interesting to note, however, the 



18 



