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<br />Or:." r>.,,, <br />t1J0~l,,; <br /> <br />(3) Bank storage coefficient - The bank storage coefficient is <br />defined as the ratio of the recoverable volume of ground water <br />in storage in the banks to the volume of water stored in the <br />reservoir as surface storage. Water entering or leaving the <br />banks is assumed to do so instantaneously with a rise or drop <br />of the reservoir surface elevation. Bank storage coefficients <br />are shown in Table 1. Values for Lakes Powell and Head are those <br />currently accepted as rough values, while those for Lakes ~Iohave <br />and Havasu are assumed identical to Lake Head values. <br /> <br />~ <br /> <br />Reservoir Evaporation Hates <br /> <br />Average monthly reservoir evaporation rates were used for all runs. <br />Values for Lake Powell, based on an evaporation study made by the <br />Upper Colorado Region during the mid-1960's, are net (Le., the <br />difference between evaporation and rainfall, rates). Lake Head val- <br />ues are gross fir,urc$, ""1';11 \(',1 by John HendricJ.-. These values, <br />based on Hendrick's dissertation,[6, pp 59-69] are averages for the <br />1953-1969 period. V"llles for Lakes Mohave and Havasu are assumed <br />identical to those for Lake Head. Rates for Lakes Powell and Mead <br />are given in Table II. <br /> <br />l <br />~ <br /> <br />Ungaged Tributary Inflows <br /> <br />Ungaged tributary inflows are defined as those inputs occurring <br />between successive river stations required to assure mass balance <br />in the system. They include true ungaged inflows as well as activ- <br />ities known to occur but not explicitly accounted for (i.e., irri- <br />,gation projects, diversions, etc.). In addition, the values are <br />also functions of the conceptual model of the river system between <br />the successive stations. A lack of measured data is the motivating <br />force behind the ungaged inflow approach. <br /> <br />Practically, the computation of ungaged inflows results in all errors <br />being reflected in the computed inflows. As a consequence, they act <br />as a receptacle or "trash basket," receiving the effects of measure- <br />ment errors, mistakes, assumptions, and approximations. When all of <br />the available data are used, there is no information left to verify <br />the model. Although this is undesirable, it is the price paid for <br />an inadequate data collection program. <br /> <br />The general approach for computing ungaged inflows of water and salt <br />is detailed in Appendix B. Specific information relating to each <br />reach follows. Present modified data are generally used in the com- <br />putations. Tabulated and plotted results are given in Appendix C. <br /> <br />10 <br />