use of a computer-controlled data acquisition system it may be possible 

 to identify the chain of events which cause high runups. This approach 

 would be somewhat novel since it would be considering the characteristics 

 of two or three waves which interact to produce one runup. 



In addition to the above approaches for predicting runup, the methods 

 of Battjes (1971) and van Oorschot and d'Angremond (1968) should be 

 investigated. Battjes' method of runup prediction was based on the joint 

 distribution of wave heights and periods, and was similar to Saville's 

 (1962) approach except Battjes produced a formula of the type developed 

 by Hunt (1959). van Oorschot and d'Angremond (1968) also used Hunt's 

 formula; however, their approach was based on the spectral characteristics 

 of the waves. 



VI. SUMMARY AND CONCLUSIONS 



The wave runup board-gage developed for this study generally worked 

 satisfactorily. Without the runup gage it would have been impossible to 

 accurately record the runup extremes caused by irregular waves. In 

 addition to providing the runup maximums and minimums, the runup gage gave 

 a complete time history of the air-runup interface on the slope. Improved 

 instrumentation techniques should permit the development of an improved 

 runup gage similar to the one used in this study. 



The maximum runups of irregular waves are greater than those of mono- 

 chromatic waves even when the runups are normalized by dividing by the 

 root mean square water surface displacement, i.e., standard deviation of 

 the wave record. Observations of irregular wave runup suggest the 

 following two general reasons why it is greater than the runup of mono- 

 chromatic waves: (a) the growth of the largest waves (or probably more 

 significant, the growth of the highest crests) as measured by root mean 

 square water surface displacement, as conditions progress from monochro- 

 matic to complex; and (b) the irregular arrival of waves of different 

 amplitudes near the Stillwater line, and their interaction with the return 

 flow of previous runups, occasionally create the opportunity for unusually 

 high runups. 



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