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<br />ui <br />~ <br /><( <br />:c <br />() <br />en <br />o <br />o <br />w <br />~ <br />~ en 1.5 <br />00:: <br />zw <br />"lij <br />f2~ <br />w~ <br />C) <br />~ <br />en <br />~ <br />w <br />~ <br />0:: <br />() <br />W <br />o <br /> <br />100 <br /> <br />CIt <br />N <br />'(jii <br />'t:J <br />Je <br />(\J <br />u <br />:s <br />c <br />c 50 <br />(\J <br />.s: <br />- <br />... <br />CIt <br />C <br />u:: <br />~ 25 <br />1:! <br />CIt <br />a.. <br /> <br /> <br />002371 <br /> <br />2.5 <br /> <br />2 <br /> <br /> <br />1 <br /> <br />0.5 <br /> <br />o <br />o 5 10 15 20 25 <br /> <br />DISTANCE DOWNSTREAM FROM GLEN CANYON DAM, <br />IN KILOMETERS <br /> <br />eddy. <br />sand <br />( 1999) <br /> <br />75 <br /> <br />~ <br /> <br />. <br /> <br /># <br /> <br />o <br />0.1 <br /> <br />Figure 20. (Left) Graph showing change in <br />stage at 150 m3/s, plotted as a function of <br />distance downstream from Glen Canyon <br />Dam (Grams et aI., 2004, fig. 11). <br /> <br />6 <br />:~ <br /> <br />Figure 21. (Below) Graph showing bed <br />sediment size distribution for samples in <br />Glen Canyon. Size in 1956 includes the <br />average of bed surface samples, <br />distinguishing the average of sand samples <br />and the average of bore-hole samples of the <br />underlying gravel. Size in 1966 distinguishes <br />the average size of gravel armor, gravel <br />sUbsurface, and sand. Size in 1975 is for <br />gravel armor. Samples in 1999 were <br />collected by pipe dredge from a boat at <br />approximately 1-km intervals, and the <br />indicated size is the composite of all <br />samples. Data for 1956 to 1975 are from <br />Pemberton (1976). Figure is from Grams et <br />al. (2004, fig. 6). <br /> <br />- - - 1956 <br />-1966 <br />---- 1975 <br />1999 <br /> <br />I <br />I <br />!~ <br /> <br />armormaterlal (1966) <br /> <br />I <br /> <br />III~ <br /> <br />/ arm or m"aterl al (1975) <br />I <br />I <br /> <br />1 <br /> <br />10 <br />Particle size, in millimeters <br /> <br />100 <br /> <br />1000 <br /> <br />act as the hydraulic controls of the water <br />surface profile for the 145 Ian between the <br />Lees Ferry and Grand Canyon gages. There is <br />some evidence that many rapids aggraded. <br />There is limited evidence that the bed of some <br />pools degraded. There is no evidence of <br />longitudinally extensive multi-year accumula- <br />tion of fme sediment on the bed. <br /> <br />5.3 Post-dam Changes in the Bed in Marble <br />and Upper Grand Canyons <br /> <br />There is no evidence for longitudinally <br />consistent changes in stage-discharge relations <br />in Marble and Grand Canyon, because <br />bouldery rapids have not eroded. These rapids <br /> <br />32 System-wide Changes in the Distribution of Fine Sediment in the Colorado River Corridor ... <br />