replaced with crushed coal to create a movable bed which represented the 

 Lakeview Park contours. Still-water levels (SWL's) were adjusted so that 

 depths in the model were comparable to those in the area of Lakeview Park. 



8. Model tests were initially conducted for the as-constructed project 

 at Lakeview Park. After examining many combinations of wave height, period, 

 direction, and SWL, test conditions were selected which produced a stabilized 

 shore similar to that observed in the prototype (as evidenced by a series of 

 aerial photographs) . The shoreline configuration obtained in the model for 

 the as-constructed plan is shown in Figure C8. 



9. Test data were secured for rubble-mound extensions of the west groin 

 and west breakwater, and various combinations of these modifications. The 

 recommended plan, with respect to beach protection and economics, consisted of 

 a 30.5-m-long extension of the west groin toward the western head of the west 

 breakwater segment (Figure C9) . This resulted in a smaller opening between 

 the groin and breakwater; therefore, less wave energy penetrated the opening 

 and only minor retreat of the west-end shoreline occurred. The test condition 

 with the west groin totally removed resulted in a wider beach at the project's 

 west end than that observed with the west groin in place. This illustrates 

 the significance of the groin in causing the local erosion. This model test 

 was a qualitative study and quantitative interpretations should not be made. 

 However, relative comparisons for the various test plans using the same test 

 conditions should be valid. 



Oceanside Beach Model Study 



10. Curren and Chatham (1980) conducted a model study on Oceanside 

 Beach which is primarily a recreational beach located on the Pacific Ocean 

 approximately 129 km southeast of Los Angeles and 48 km northwest of San 

 Diego, California. Since construction of Del Mar Boat Basin in 1943, per- 

 sistent erosion of Oceanside Beach has occurred, accompanied by accretion of 

 sand in the harbor and entrance channel. 



11. A l:100-scale hydraulic model was constructed (representing 

 37.8 sq km in the prototype) and used to investigate the arrangement and 

 design of proposed structures for the prevention of shoaling at Oceanside 

 Harbor and the prevention of beach erosion at Oceanside Beach. Various groin 



C9 



