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2 <br />2 <br />1 <br />w <br />d 1 <br />Q <br />E 1 <br />to <br />N 1 <br />O 1 <br />y? <br />9 <br />E <br />z <br />CAMEO PRE-PEAK <br />2 <br />2 <br />1 <br />m 1 <br />CL <br />E 1 <br />a <br />N 1 <br />O 1 <br />a <br />E <br />0 <br />z <br />CAMEO POST-PEAK <br />Suspended Sediment Concentration (mg/1) <br />CISCO PRE-PEAK <br />m <br />a 1 <br />E <br />co <br />N 1 <br />w <br />O <br />E <br />z <br />Suspended Sediment Concentration (mg/1) <br />d <br />CL <br />E <br />a <br />N <br />w <br />O <br />a <br />E <br />z <br />CISCO POST-PEAK <br />Figure 13. Comparison between suspended sediment concentrations of pre- and post-peak samples <br />from the Colorado River near Cameo, CO, and the Colorado River near Cisco, UT. <br />The second part of this analysis focused on the long-term effects of flow regulation on sediment <br />loads. The results indicate that reservoirs and flow diversions have had system-wide impacts on the <br />streamflow and sediment-transport regimes of the Colorado River. Figure 14 shows long-term <br />trends in the average annual discharge and suspended sediment load of the Colorado River at these <br />four gauges (see Appendix Table A-1 for a listing of the annual values). The trends at each site are <br />similar, with the annual variations in suspended sediment load generally mimicking the annual <br />variations in discharge. However, at all sites the variability in annual sediment load is greater than <br />the variability in annual discharge. This is a consequence of the nonlinear relation between water <br />discharge and sediment load (eqn. 2), which can result in large differences in load for small <br />differences in flow. In statistical terms, the differences in streamflow and sediment-load are <br />reflected by the respective values of the coefficient of variation, C, (Table 5). Note that the C, of the <br />annual sediment loads ranges from 0.66 to 0.82, whereas the C, of the annual discharges ranges <br />from 0.29 to 0.40. Stating this another way we can say that the deviation in average annual <br />suspended sediment loads is roughly twice the deviation in average annual discharge. <br />23 <br />1 0 100 1000 10000 <br />Suspended Sediment Concentration (mg/1) <br />10 100 1000 <br />1 0 100 1000 10000 <br />10 100 1000 <br />Suspended Sediment Concentration (mg/1)