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<br />. <br /> <br />. <br /> <br />Our goal in studying these sites is to evaluate patterns of sediment <br />transport and deposition in relation to specific discharges. We <br />plan to re-survey the cross sections at each of the 4 study sites <br />beginning in spring 1994 and periodically thereafter through the <br />summer. We will also make measurements of the substrate (particle <br />size) at each site; point-count samples will be taken in coarse <br />substrates and bulk samples will be taken in fine substrates At one <br />of the study sites, we propose to make a series of flow and <br />suspended-sediment measurements in the side channel to examine how <br />transport and deposition are related. Typically, the peak in <br />suspended sediment concentration is not in phase with water <br />discharge, and we are interested in whether patterns of deposition <br />in side channels are related to a lag in suspended sediment <br />concentration. These measurements will be made at the downstream <br />end of one of the side channels. A likely site for these <br />measurements occurs on the left bank of the river about 2 miles <br />upstream of the Fruita bridge. Access to the site is through <br />private property, but we have the permission of the land owner to <br />conduct this work. All of the equipment, including surveying <br />instruments, current meters, and samplers, is available through the <br />CU Geography Department. <br /> <br />2. Historic changes in the Ruby-Horsethief Canyon reaches: changes in <br />channel morphology in the Ruby-Horsethief Canyon reaches will be <br />analyzed using aerial photographs flown in 1937, 1954, 1968, and <br />1986. These particular aerial photographs are of a 1:9600 to <br />1:24000 scale, and except for the 1986 set, all were taken at flows <br />of about 2,500 cfs. On the basis of our recent analysis of aerial <br />photographs in the 15- and l8-mile reaches, we know the boundaries <br />of the channel, including the banks, islands, and emergent channel <br />bars are easily visible on the aerial photographs. On each photo <br />set, the channel and bar boundaries will be digitized and measured <br />with a computer aided design system (CAD) and a geographic <br />information system (GIS). There are several advantages to using <br />CAD-GIS techniques vs. manually tracing and measuring channel <br />features on mylar overlays: first, it takes no longer to digitize <br />features than to trace them, and once the data are in a digital <br />format, the channel maps can easily be adjusted to a common scale; <br />second, the GIS is especially useful for extracting different <br />measures of channel change such as percent of channel area occupied <br />by bars, or the deviation in channel width; and third, it is <br />possible with the GIS to treat explicitly the amount of error <br />involved in the analysis. All of the image processing equipment <br />needed to conduct this work is available in the Geography Department <br />of the University of Colorado. <br /> <br />3. Personnel: the project will be a cooperative effort between <br />biologists from USFWS (Pfiefer, McAda and Osmundson) and <br />geomorphologists from the University of Colorado (Pitlick and Van <br />Steeter). Most of the field measurements will be carried out by the <br />University of Colorado team in consultation with the Grand Junction <br />staff. Pitlick has extensive experience making these types of <br />measurements in rivers similar to the Colorado River, and he will be <br />on hand for most of the field work. Van Steeter, under Pitlick's <br />supervision, will be responsible for analysis of aerial photographs <br />and compilation of data and maps. <br /> <br />3 <br />