STRUCTURE SLOPE, COT a 



Figure 12. Rough estimate of the percentage of 

 breaking waves 



percentage of waves in a spectrum that will break. Figure 12 was generated by 

 combining several equations discussed by Battjes (Battjes 1974; Equa- 

 tions 2.3.5 — Iribarren and Nogales' breaking criterion, and 7.6.16 — steepness 

 distribution function). Note that for steeper structure slopes, fewer waves 

 will break on the structure; therefore, Battjes' method will be less 

 applicable. 



36. Battjes' assumption of Rayleigh-distributed wave heights and 

 wavelengths is commonly accepted as a reasonable approximation in deep water, 

 but not in shallow water. For example, recent work by Ochi, Malakar, and Wang 

 (1982) shows that shallow-water waves can be far from Rayleigh distributed. 



By making this assumption, Battjes' method may systematically overestimate or 

 underestimate overtopping rate. 



Owen's Method 



37. Owen (1980) measured overtopping caused by irregular laboratory 

 waves. Based on the results, an equation is presented for estimating irreg- 

 ular wave overtopping rates: 



21 



