335. A similar division was developed in this study to more closely 

 relate transport rate properties to local wave characteristics. Figure 43 is 

 a definition sketch illustrating division of the profile into four zones. 

 Wave breaking in the surf zone (excluding the swash zone) can be separated 

 into two hydrodynamic regions according to the scale and intensity of the 

 induced vortices, as described by Miller (1976), Svendsen, Madsen, and Buhr 

 Hansen (1979), Basco (1985), Jansen (1986), and others. Svendsen, Madsen, and 

 Buhr Hansen called the region extending shoreward of the wave breaking point 

 for a distance of several breaker depths the "outer or transition region." 

 The more seaward region of the surf zone was called the "inner or quasi-steady 

 state region." The outer region is characterized by large vortices and 

 splash- jet motions, whereas the inner region is characterized by bore-like 

 movement and more gradual change in internal fluid motion. The aforementioned 

 studies showed this classification to be valid for both spilling and plunging 

 breakers, with the intensity of the process being less for spilling breakers. 

 Thus, when waves break, either by spilling or plunging, there is a certain 

 distance between the incipient break point and the location where the waves 

 are fully broken (where the energy dissipation achieves a maximum or near- 

 maximum) . Sunamura (in press) similarly hypothesized a plunge point for 

 spilling breakers in analogy to that for plunging breakers. Skjelbreia (1987) 

 conducted a detailed laboratory study of reproducible breaking solitary waves. 

 He reviewed the literature of the wave breaking process and defined four zones 

 of shoaling wave transformation as gradual shoaling, rapid shoaling, rapid 

 decay, and gradual decay. These zones are similar to those developed in the 

 present work based on considerations of cross -shore sand transport, discussed 

 next. 



Transport Regions 



336. Various regions having distinct sand transport relationships were 

 defined based on generally accepted concepts of nearshore wave dynamics , 



in accordance with Figure 43. One region, known as prebreaking, extends from 

 the seaward limit of significant profile change to the break point, denoted as 

 Zone I. In the prebreaking region the transport rate is influenced by trans - 



137 



