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<br />O 0.' ''"1 <br />..:i. d 't', <br /> <br />In the demand data base, an annual withdrawal in acre-feet is specified <br />for each user at each demand point. A depletion is specified for each <br />withdrawal. Lag time in 'nonths (up to 10 months) for the return flow <br />can also be specified. Values of withdrawal and depletion are specified <br />for an initial year and for each year there is a change in withdrawal or <br />depletion. Withdrawals and depletions can be "fixed" amounts, held <br />constant for a number of years, or they can be "trended" amounts, <br />varying linearly over a number of years (see section 11.1). In both <br />cases, a monthly distribution of the withdrawals and depletions is spec- <br />ified for each demand point. <br /> <br />The "salt pickup" of a return flow is specified in mg/L (milligrams/ <br />liter). This value can be either positive or negative and is used to <br />simulate either salt leached from irrigated land and picked up by return <br />flows (+), a reduction in salt load from a water quality improvement <br />project (-), or any similar increase or decrease (+ or -) in salt load <br />not associated with a concentration change due simply to a change in the <br />volume of water in the river from a depletion or evaporation. <br /> <br />The reach and sequence point associated with each demand is also spec- <br />ified in the demand data base, as is the reach and sequence point of the <br />return flow which is associated with a given demand. In addition, flags <br />are set that can indicate one of three special cases. The first case is <br />an export. An export is a demand with no return flow that diverts water <br />at a specific salt concentration. The salt concentration is specified <br />in the demand data base. Thi s allows a demand wi th no return fl ow to <br />divert water at a concentration different from the concentration in the <br />river at the point of diversion. An export is used when the actual <br />river diversion is upstream of the first hydrology inflow point modeled <br />by the CRSM. (The point of diversion must, of course, be modeled <br />downstream of the first hydrology inflow point.) <br /> <br />The second special case is a water quality improvement or salinity <br />project. Thi s type of project reduces rather tha t increases the amount <br />of salt in the system and the flag is set so that any associated "salt <br />pickup" is treated as a negative value. The third special case is a <br />diversion made directly from a reservoir. An example of such a demand <br />is the Navajo Indian Irrigation Project, which is diverted from Navajo <br />Reservoir. Reservoir diversions require special handling because the <br />ability to meet such a demand is dependent upon a reservoir elevation <br />and not on the inflow or release downstream of the reservoir. <br /> <br />Additional data contained in the demand data base include the state in <br />which the demand occurs, and use of the demand. The nine uses <br />recognized are (1) thermal power, (2) agriculture, (3) fish, wildlife, <br />and recreation, (4) minerals, (5) water quality improvement, (6) munici- <br />pal and industrial, (7) exports, (8) coal gasification, and (9) oil <br />shale. <br /> <br />Information used to control the output is also included in the demand <br />data base file. These include such things as type of output reports <br />desired (see section 4.4) and years of output data desired. <br /> <br />14 <br />