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11 <br /> Andrews Coefficient Pucherelli Coefficient <br /> Qe Width a Width a <br />Jensen pre 20,500 700 4.9 700 4.9 <br />post 11,500 610 5.7 665 6.2 <br />Green River pre 26,500 515 3.2 470 2.9 <br />post 20,500 465 3.2 455 3.2 <br />The assumption of constant coefficient <br />the vicinity of the Green River, Utah, <br />for the reach of the Green River near <br />apparent equilibrium following closure <br />of the prereservoir period. <br />appears valid for the Green River in <br />gauge. The value of the coefficient a <br />the Jensen gauge for <br />of Flaming Gorge is <br />the period of <br />not equal to that <br />Carling [13], in a recent review of channel changes related to river regula- <br />tion, asserts that a much more complex model is required to adequately <br />describe the range of channel adjustments following regulation. These adjust- <br />ments are likely to involve thresholds and feedback mechanisms that are uni- <br />que to the river studied. Also, the sequence of large floods following <br />regulations plays an important role in determining the long-term stability of <br />a channel. <br />The Geological Survey gauge on the Green near Ouray, Utah, (see figure 1) was <br />operated from 1947 to 1966 in an alluvial portion of the channel. Comparisons <br />of channel shape characteristics before and after flow regulation by Flaming <br />Gorge are shown in figures 16 and 17. Both channel width and average channel <br />depth changed following flow regulation. Over a similar range of discharges, <br />the width of flow was significantly narrower during 1963-1988 relative to <br />Average channel depth increased significantly during the latter time period <br />relative to the prereservoir period. The comparisons of least-squares <br />regression lines for these data (see table 6) were significant at the <br />0.05 level using the analysis of covariance test described by Snedecor and <br />The short postregulation period of record for this gauge and its distance <br />downstream from Flaming Gorge limit the attribution of these changes solely to <br />the flow changes wrought by regulation. The trends of decreasing width and <br />increasing depth are consistent with the relationships given by Schumm [8], <br />[9] for the changes in discharge and sediment load experienced in the Green <br />following regulation, see Andrews [3]. <br />Andrews and Nelson [15] investigated the response of the Green River channel <br />to changes in discharge at a site approximately 1 mile in length near river <br />mile 255. Their review of the historical aerial photography for this area <br />indicated that channel conditions in this reach have been essentially <br />unchanged since 1963, when regulation by Flaming Gorge began. Using a sedi- <br />ment and water routing model described by Smith [16] they developped predic- <br />tions of channel response for three flows, 16,775 ft/s, 9,710 ft3/s and <br />1,770 ft3/s. <br />Their modeling indicated that the Green River channel bed topography adjusts <br />rapidly (on the order of a few to several days) to changes in discharge.