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<br />. <br /> <br />. <br /> <br />Determine changes in bedload at Diamond Creek. <br /> <br />Justification: <br />Stream stage discharges have not been measured during <br />GCES under low and fluctuating flows because high water <br />releases occurred during the early years of GCES. <br />Accurate discharge read1ngs are necessary to better <br />develop the flow routing model for the system. During <br />the constant flow, stream discharge data will be used <br />to determine how long it takes for the system to reach <br />an apparent equilibrium at a constant 5000 cfs. This <br />can be used to estimate other rates for reaching <br />equilibrium at other flows and will allow for more <br />accurate requests for prescribed flows in the future. <br />With the system switching from fluctuating flows to <br />constant flows, the bedload data at Diamond Creek <br />should indicate how stable the bedload is at a constant <br />flow and how the change effects the bedload. The data <br />on the discharges from the dam have not always agreed <br />with stream gage discharge data during fluctuating <br />flows. Comparisons of these data during constant flows <br />should allow establishment of a quantitative <br />relationship between these measurements. <br /> <br />Methods: <br />Stream discharge gages (cables and cable cars) will be <br />established at six locations between Glen Canyon Dam <br />and Diamond Creek but for this study only four will be <br />used. These are: Glen Canyon Dam, Lee's Ferry, Grand <br />Canyon and Diamond Creek. <br /> <br />, <br /> <br />Data collection platforms may be established at each <br />location to allow continuous monitoring of stage <br />discharge with recorders as well as monitoring of <br />additional stream parameters such as water chemistry. <br /> <br />Preliminary discharge measurements will be made during <br />the gage setup and beach monitoring trips in early <br />September. <br /> <br />Pre-constant flow (fluctuating flows) gage <br />be made during the gage installation trip. <br />will also be made during the constant flow <br />constant flow periods. <br /> <br />ratings will <br />Ratings <br />and post- <br /> <br />Bedload sampling will only be made at Diamond Creek. <br /> <br />Measurement and/or sampling periods for gage ratings, <br />stage discharge calibration and other samples (e.g., <br />water chemistry) will be staggered to take advantage of <br />short personnel time and mass movement of water units. <br />These sampling times will be: <br /> <br />3 <br />