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<br />r~~ J~ ~. <br /> <br />~.6 <br /> <br />Justification: The total sediment budget of the canyon is <br />dependent, not only on how much is stored in various forMs <br />(e.g., pre-dam terraces. beaches, channel, eddies), but on <br />how Much is moving into the system trom tributaries, in <br />relationship to tributary flood frequency and stability of <br />pre- and post-dam deposits, and within and through the <br />system. Factors that might cause an increase in sediment <br />transport will probably delay or prevent future development <br />of an equilibrium in the canyon sediment dynamics. If an <br />operation scheme could be identified that reduced to a <br />minimum the transport of sediment through and out of the <br />system, then net storage of sand may be increased. <br /> <br />Intoraation Needs: A discharge (flood) routing model needs <br />to be developed. This will require river channel topography <br />(bathymetry) and a series of periodic measurements of <br />discharges stages (in actuality mini-flood stages) at the <br />gages through the canyon. The bathymetry can be developed <br />from aerial photographs taken during a low constant <br />discharge (see ~-1.1). Sediment deposit stability, <br />tributary and mainstream tlood frequency can be determined <br />from analyses of pre-dam alluvial terrace staqejdischarge <br />relationships. Suspended sediment will be sampled during <br />constant, controlled fluctuating and normal opGrations <br />discharges at the six gaging stations 1n the Canyon (Glen <br />Canyon DAm, Lee'. Ferry, Little Colorado, Grand Canyon, <br />National Canyon and DiamOnd Creek). Bed load transport will <br />be sampled at the same time as suspended sediment sampling <br />but at few gAges (e.g., Lee's Ferry, Grand Canyon and <br />National canyon). <br /> <br />The following secondary hypotheses can be tested under the <br />research program established to test H.-3.l, especiallY using a <br />series ot ditterent re.earch discharge groupings. <br /> <br />&.-3.1a. There is no significant relationship between the <br />maqnitude of daily discharqe fluctuations and the amount of <br />sediment stored in or transported through the canyon system. <br /> <br />H.-3.1b. There is no significant relationship between the <br />magnitUde of the daily minimum discharge and the amount of <br />sediment stored in or transported throuqh the Canyon system. <br /> <br />&'-3.1C. There is no significant relationship between the <br />rat. ot change of fluctuating discharges and the amount of <br />sediment stored in or transported through the Canyon system. <br /> <br />H.-3.1d. There is no significant relationShip between the <br />variations in discharge due to dam operations. flooding frequency <br />and equilibration of sediment storage in the Canyon system. <br /> <br />6 <br />