reaching an equilibrium volume. However, the main breakpoint bar had to 

 develop to a certain size before the trough shoreward of the bar was suffi- 

 ciently deep to allow the waves to reform. Formation of a second bar was 

 manifested in the transport rate distribution as a local minimum, indicating 

 that material was deposited shoreward of this point, implying a negative 

 derivative of the transport rate. A local minimum in the transport rate was 

 typically found only in the first few transport rate distributions of a run, 

 since the second breakpoint bar soon attained equilibrium. 



352. The present data sets do not provide sufficient information to 

 determine reliable quantitative empirical relationships for the net transport 

 rate in areas of wave reformation. Some qualitative observations may be made 

 from the data with regard to the shape of the transport rate. The transport 

 rate decayed in the seaward direction from a point located somewhat shoreward 

 of the second break point, and the spatial decay in the net transport rate 

 appeared to be more gradual than for the region seaward of the main breakpoint 

 bar. It is speculated that even though breaking ceases, more turbulence is 

 generated or convected in areas of reformation than in the area seaward of the 

 main breakpoint, thus making the decay of the transport rate in wave reforma- 

 tion zones more gradual . 



Zone II: Net transport rate between break point and plunge point 



353. Waves must propagate shoreward a certain distance from the break 

 point before breaking fully develops and energy dissipation reaches a maximum 

 (Miller 1976; Svendsen, Madsen, and Buhr Hansen 1979; Basco 1985; Jansen 1986; 

 Basco and Yamashita 1987; Svendsen 1987). This distance appears to be 

 approximately equal to the plunge distance for plunging breakers and provides 

 the basis for a definition of an equivalent plunge distance for a spilling 

 breaker. The shape of the main breakpoint bar was in many cases well approxi- 

 mated by two linear slopes on the seaward side of the bar (see Part IV). The 

 break in slope was located in the vicinity of the break point, indicating that 

 the properties of the net transport rate were different in regions seaward and 

 shoreward of the break point . 



354. It proved too difficult to determine quantitative characteristics 

 of the net transport rate in the region between the break point and the plunge 

 point. This region is of small spatial extent. Furthermore, the breaker 



145 



