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<br /> <br />002068 <br /> <br />. <br /> <br />Computations commence with an upstream reservoir and proceed <br />downstream through successive reservoirs. Any water above the <br />dam crest must spill. In addition, it is assumed that if water <br />is in the spillway-dam crest zone at the end of the month, the <br />required minimum daily spill must occur during each day of the <br />month. * The total volume for the month is then compared to the <br />total releases made during normal operations (exclusive of water <br />above the dam crest). If it exceeds the releases, the difference <br />is the additional release necessary to satisfy the minimum flow <br />constraint. This additional release is then compared to the <br />volume of water which would lower the reservoir to the spillway <br />crest level. If this volume is less than the additional release, <br />the release is set equal to the volume. Under no circumstances <br />will uncontrolled spills lower the reservoir below the spillway <br />crest. <br /> <br />. <br /> <br />The total uncontrolled spills are the sum of the additional release <br />to satisfy minimum spills and the water above the dam crest. The <br />same procedure is used when there is no water above the dam crest. <br />If the spill option is used, the spills are allocated to variable <br />exports, released from the reservoirs, and routed to the element <br />containing the export. Since only a portion of the total spill <br />may be allocated, the remainder is computed and saved as the <br />spills remaining to be released. If the spill option is not used, <br />the remaining spills equal the originally computed total. <br /> <br />The program now determines if the excess water option is being <br />used. If it is, the amount of excess water exclusive of any spills <br />is computed and added to any remaining spills. The total is then <br />allocated to the variable exports, released, and routed. Finally, <br />the excess water allocated and released is compared to the <br />remaining spills to determine if all the required spills were <br />satisfied. If they were not, sufficient water is released to <br />satisfy the minimum flow constraint. When the excess water option <br />is not used the additional release equals the remaining spills. <br />Spills that are not allocated are routed to and stored in the <br />first downstream reservoir. <br /> <br />It should be noted that certain details are lost and replaced by <br />approximations established by program assumptions whenever levels <br />fluctuate between zones during a given month. Thus, transitions <br />between the normal operating zone and the zone above the spillway <br />crest or below the top of the dead storage pool produce approximate <br />results. Refinement would require shorter time increments and <br />capacity constraints continuous with reservoir levels. <br /> <br />. <br /> <br />* This is obviously an approximation to reality. <br />of days during which uncontrolled spills occur is <br />because the monthly time frame is too large. <br /> <br />The actual number <br />a detail lost <br /> <br />3-6 <br /> <br />