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1 <br /> <br /> <br /> <br />LJ <br /> <br />1 <br />I~ <br />~J <br />1 <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br />The longitudinal profile of most large rivers is generally concave up [Leopold et al., <br />1964], and has larger bed material and steeper gradients in the headwaters and lower gradients <br />and smaller grain size downstream. The Green River below Flaming Gorge Dam passes through <br />formations of differing erosional resistance [Schmidt and Rubin, 1995], such as the harder, <br />resistant Uinta Mountain group in Dinosaur National Monument [Hansen, 1986], the less <br />resistant Duchesne and Uinta Formations of the central Uinta Basin, and the more resistant Mesa <br />Verde sandstone in Gray Canyon. The channel shape and gradient are partly adjusted to these <br />varying resistances [Grams and Schmidt, in press]. Downstream from Flaming Gorge Dam, the <br />Green River has steep-gradient, eddy-dominated canyon reaches with large bed material <br />interspersed with low-gradient, sand-bedded alluvial reaches and forms a complex longitudinal <br />profile (Figure 4) [Schmidt, 1994; Schmidt and Rubin, 1995]. The Green River in the central <br />Uinta Basin is the area of interest for this study. In this area, the Green River has the lowest <br />gradient of any reach of the Green River in Utah, and is sand-bedded. The study reach is located <br />within the Ouray National Wildlife Refuge. <br />1800 <br />w <br />1700 <br />w <br />o' 1600 <br />a <br />a 1500 <br />z 1400 <br />0 1300 <br />a <br />'w 1200 <br />w <br />1100 <br />OURAY NWR <br />FLAMII~TG GORGE <br />DAM <br />0 100 200 300 400 500 600 700 <br />RIVER KILOMETERS FROM THE COLORADO RIVER CONFLUENCE. <br />Figure 4. Longitudinal profile of the Green River between Flaming Gorge Dam and the <br />confluence with the Colorado River. Adapted from Schmidt [1994]. <br />A-13 <br />