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<br />12 <br /> <br />uninterrupted record of channel geometry to the present. Each discharge <br />measurement includes water depth at a minimum of 20 points across the <br />channel. Distance across the channel is determined from markings on the <br />cable that have remained constant over time. Each cross-sectional <br />measurement also includes river stage, discharge, width, depth, mean velocity, <br />and thalweg depth. Data from these discharge measurements were entered <br />into a spreadsheet for analysis. Measurements made during periods with <br />extensive shore ice were inconsistent with other stage-discharge relations and <br />were excluded from the analysis. <br />Reconstruction of a channel cross section from discharge measurements <br />is computed by subtracting water depth from water stage. In the case of the <br />. Green River gage, however, the gage itself is located approximately 1 km <br />upstream from the present cableway. Water surface elevation data were <br />collected near the cableway and coupled with discharge information from the <br />gage. We used these data to establish a stage-discharge relation at the <br />cableway for comparison with the relation at the gage (Fig 5). The relation at <br />the cableway was the same as the present relation at the gage for flows greater <br />than 600 m3/s. Adjustments were made to the discharge measurement data to <br />ensure proper vertical positioning of the cross sections during analysis. <br />Since one focus of this research was to determine changes in active <br />channel width, it was necessary to develop a method for extracting this <br />information from the large data set of discharge measurements. Measurements <br />