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<br />. <br /> <br />BENEFITS OF RESERVOIR-RELEASE MANAGEMENT <br /> <br />. <br /> <br /> <br />The data presented in tables 4 and 5 provide information on how <br />reservoir releases may be managed to reduce transit losses. Generally, the <br />smaller the antecedent streamflow, the greater the transit loss. For a given <br />release volume, scheduling the release for the longest duration and during <br />the greatest antecedent streamflow will result in the smallest transit loss. <br />Transit losses of a base release from Pueblo Reservoir to selected sites <br />along the study reach are shown in table 7, which was derived from tables 1 <br />and 4. For the entire reach, transit losses for a base release range from <br />about 7 percent or 0.05 percent per mile during a period of very high <br />antecedent streamflow, to more than 50 percent or 0.35 percent per mile <br />during a period of very low antecedent streamflow. <br /> <br /> <br />Traveltime information is valuable in the management of reservoir <br />releases. Stage changes indicating the arrival of'a release are generally <br />difficult to recognize in the area downstream from the stream-gaging station <br />at Catlin Dam (site 12, fig. 1), particularly when streamflow is unstable <br />because of tributary inflows, diversion changes, canal sluicing, or other <br />causes. Should diversion begin either too early or too late, streamflow <br />downstream from the point of diversion may be temporarily disrupted both at <br />the beginning and the end of the diversion period. <br /> <br />The use of several incremental diversion rates also will minimize <br />unstable downstream streamflow conditions during the diversion period. <br />Reservoir releases, although they are usually made at a single rate, <br />attenuate rapidly as they travel downstream. If the canal diversion also is <br />made at a single rate, the 'result can be a sudden decrease in downstream <br />streamflow when the diversion begins and a sudden Increase when the diversion <br />ceases. <br /> <br /> <br />Average times of rise or fall for release hydrographs are given in <br />table 8 for each sub reach during various antecedent streamflow conditions. <br />These data were obtained through analysis of hydrographs developed by the <br />computer model. An example of how to use these times to determine a <br />diversion schedule' is given in table 8 and is Illustrated on figure 8. The <br />number of diversion increments used at both the beginning and ending of the <br />diversion period needs to be at least equal to the subreach number in which <br />the diversion is located to avoid significant adverse effects on water users <br />downstream from the point of diversion. A diversion in subreach 4 would, <br />therefore, use at least four incremental diversion rates before reaching Its <br />maximum diversion rate. <br /> <br />I <br />, <br /> <br />! <br />I <br />i <br />I <br />1 <br />! <br />! <br /> <br />24 <br />