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<br />001825 <br /> <br />estimated by using average yearly concentrations based on the <br />annual historic flows and salt loads of the ~MD export which <br />were multiplied by the 1970 volumes.* <br /> <br />The initial reservoir salinity used in computing the ungaged <br />inputs was assumed equal to the mean annual I~~D concentration <br />for 1941. The effect of the initial salinity on the results of <br />the computations is regarded as relatively minor. <br /> <br />Ungaged inputs were computed using bank storage coefficients of <br />0.0 and 0.06. This permitted evaluation of the effect the coef- <br />ficient has on the results. Tables C-22 through C-24 contain <br />results for the 0.0 bank coefficient. The 0.06 results are given <br />in Tables C-25 through C-27 and Figures C-24 through C-26. A com- <br />parison of the sample descriptive statistics follows: <br /> <br />Item 0.0 bank 0.06 bank <br />Flow - mean 5,000 acre-feet 5,000 acre-feet <br /> - standard <br /> deviation 105,000 acre-feet 110,000 acre-feet <br />Salinity - mean -27,000 tons -27,000 tons <br />mass - standard <br /> deviation 91,000 tons 93,000 tons <br />Salinity - mean -202 ppm 45 ppm <br />Concentration - standard <br /> deviation 11,877 ppm 9,776 ppm <br /> <br />The fact that the mean mass values are identical for the two coef- <br />ficients is not surprlslng. Upstream inflows, downstream outflows, <br />and ~mD exports are identical in terms of water and salt for both. <br />Surface storage volumes, evaporation amounts, and initial reservoir <br />concentrations are also identical. Only the initial salt mass in <br />storage and gross changes in water content are greater at the higher <br />coefficient. However, because storage is relatively small in com- <br />parison to inflows and outflows, it is these flows that largely <br />determine the computed results. The slight increase in the variance <br />at the larger coefficient is due to the fact that a given surface <br />volume change represents a slightly larger total change at the 0.06 <br />value. The major effect is a shift in phase (or a lag) introduced <br />by the additional bank storage. This is reflected by the concentra- <br />tion statistics. <br /> <br />Both sets of data were used in duplicating base conditions. Results <br />at Imperial Dam were identical, indicating no effect. Results for <br /> <br />* In applying the model, In~D was treated as an export whose concen- <br />tration equaled that computed for Lake Havasu. <br /> <br />l5 <br />