120 - 



160 



500 1000 1500 



Distance Alongshore, m 



2000 2500 3000 



Figure 19. Shoreline positions northeast of the mouth of the Colorado River 

 between 1984 and 1992. Longshore distances are from NJO. {from Liang 

 1995) 



monitoring program. The results indicate a net sediment transport rate of 

 310,000 cubic meters to the southwest and a gross transport rate of 

 580,000 cubic meters. These results are discussed further in Chapter 5. 



Impoundment Basin Surveys 



In addition to the beach profiles, other bathymetry surveys were made 

 across the impoundment basin and navigation channel by CERC and SWG 

 persormel. Because of more complete coverage, the SWG surveys were used 

 for analysis. Locations of the SWG impoundment basin survey range lines are 

 shown m Figure 2, a plan view of the project site, and Table 7 provides survey 

 data availability. 



Initial SWG impoundment basin surveys were taken in March 1990, just 

 after the basin had been dredged. Subsequent surveys analyzed in this report 

 continued until September 1992, when new dredging operations in the 

 impoundment basin began. Dredging volimies are shown in Table 8. 



The survey data were input into the Interactive Survey Reduction Program 

 (ISRP) for processing (Birkemeier 1984). To calculate volume changes along 



36 



Chapter 4 Data Observations and Analyses 



