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<br /> <br />0'0'2 \) 4 S . <br /> <br />. <br /> <br />where Vr is the total change in storage (L3) <br /> <br />In practice, V is either the inflow to or release from a <br />reservoir. Fot input-output purposes, the surface storage <br />volume is used and can be obtained by rearrangement of <br />Equation (2). <br /> <br />The bank storage coefficient is assumed to be a single valued, <br />nonnegative constant. It is independent of whether the <br />reservoir is filling or lowering. This assumption may be very <br />poor for the initial filling cycle since a significant portion <br />of the water entering dry formations is lost to water retention <br />by the soil particles. It is also assumed that water enters <br />or leaves the bank formation within the basic month time frame. <br />Consequently, volume changes at the end of the time frame are <br />essentially instantaneous. <br /> <br />. <br /> <br />As a consequence of these assumptions, if there is no change in <br />surface storage during a month, there will be no flow into or <br />out of the banks. In reality, this may not be true because of <br />the dynamics of ground water flow in the aquifers. The <br />hydraulic nature and geographical location of the aquifer <br />boundaries, transient effects of previous operations, and the <br />slow drainage of soil materials may all be significant. <br /> <br />Consequently, the program approach must be considered a crude <br />abstraction of reality. The bank storage coefficient should <br />be evaluated in terms of an effective or active bank storage <br />component. Thus water lost to specific retention and to <br />aquifer storage great distances from the immediate reservoir <br />are excluded. If a detailed accounting of these losses is <br />desired, they can be included in an approximate fashion. For <br />example, for the initial filling of a reservoir, water lost to <br />remote portions of the aquifer can be included as an export <br />if either field data, past studies, or a detailed aquifer <br />simulation provides estimates of the quantities involved. An <br />initial run would be required to determine the filling cycle, <br />with a subsequent run including the losses of water and salt <br />by adding an export of appropriate magnitude. <br /> <br />(2) Area-capacity relationship (Card 7-2). - Area-capacity' <br />curves are required to define the reservoir surface area for <br />evaporation computations. The program uses the fourth-order <br />polynomial: <br /> <br />A = CI + C2 Vs + C3 VS2 + C4 Vs3 + Cs Vs4 (3) <br /> <br />. <br /> <br />2-4 <br /> <br />