APPROXIMATE UPPER LIMIT OF IRREGULAR WAVE RUNUP ON RIPRAP 

 PART I: INTRODUCTION 



1 . In many locations riprap is the preferred type of shore protection 

 against wave attack. The two reasons for this are the low cost and high dura- 

 bility of stone, and the effectiveness of randomly placed stone, because of 

 its roughness and porosity, in dissipating wave energy and attenuating runup. 

 Because of these reasons, riprap has been the most studied type of revetment, 

 and its performance is well documented. 



2. Runup is one of the most important factors affecting the design of 

 revetments exposed to wave action. Generally, riprap revetments are designed 

 so that little or no runup exceeds the top of the protection. Because of the 

 inherent complexity of natural wave trains and the interaction of incident 

 waves and the return flow of previous runup on a rough, porous slope, it is 

 difficult to predict the upper limit of wave uprush on riprap. This report 

 summarizes the most important results from two unpublished studies, and pre- 

 sents formulas to calculate the approximate limit of wave runup. Both studies 

 included laboratory tests of riprap exposed to irregular wave action. The 

 formulas can be used to compute the elevation to which protection needs to be 

 extended to prevent exceedance by runup or to estimate the potential severity 

 of wave overtopping. 



