realistic incident wave heights and periods, water levels, initial beach 

 slopes, and sand grain sizes. The LWT facilities generated monochromatic 

 waves, so that phenomena associated with random waves as occur in nature, such 

 as wave grouping and long period wave motion, were absent. This simplifica- 

 tion is viewed as an asset in the present study, allowing focus on transport 

 produced solely by short-period incident waves without ambiguities. 



169. One data set was obtained in experiments performed by the US Army 

 Corps of Engineers (CE) in the years 1956-1957 and 1962 (Saville 1957, 

 Caldwell 1959, Kraus and Larson 1988a) at Dalecarlia Reservation, Washington, 

 DC. The second data set pertains to experiments performed at the Central 

 Research Institute of Electric Power Industry (CRIEPI) in Chiba , Japan (Kajima 

 et al. 1983a, b) . 



CE experiments 



170. The CE experiments were performed using American customary units. 

 Conversion is made here to metric units to achieve generality, but customary 

 units are retained for equipment specifications. The concrete tank used was 

 193.5 m long, 4.6 m wide, and 6.1 m deep (635 x 15 x 20 ft). The standard 

 operating depth of the tank was 4.6 m (15 ft), which required a water volume 

 of approximately 3,800 m'^ . A mobile instrument carriage mounted on rails on 

 top of the tank carried equipment and personnel for making measurements . A 

 picture of the CE tank is displayed in Figure 2, in which the wave generator 

 and instrument carriage are seen at the far end of the tank. 



171. The wave generator consisted of a vertical bulkhead 4.6 m (15 ft) 

 wide and 7.0 m (23 ft) high mounted on a carriage which moved back and forth 

 on rails to create the wave motion. The carriage was given oscillatory 

 movement by arms 13 m in length (42 ft 9 in.), connected to two driving discs. 

 Each disc was 5.8 m (19 ft) in diameter, weighed 12.7 tons, and was driven 

 through a train of gears by a 510-hp variable speed electric motor. Wave 

 periods between 2.6 and 24.8 sec could be generated by a gearing mechanism, 

 and the maximum usable wave height at the standard operating depth was ap- 

 proximately 1.8 m (6 ft). Figure 3 gives a view of the wave generator, where 

 the bulkhead is seen in the front of the picture and the two rotating discs 

 are distinguished in the back. The experimental facility is further described 

 by Raynor and Simmons (1964) and Kraus and Larson (1988a). 



47 



