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<br />OJiJ198 <br /> <br />SECTION IV <br /> <br />TRAVEL TIME <br /> <br />Travel time for reservoir releases has been determined for the Arkansas <br />River study reach from the Twin lakes Reservoir to the headgate of the Colo- <br />rado Canal, a distance of 162 miles. This waterway length includes approx- <br />imately two miles of lake Creek and 160 miles of the main stem of the Arkansas <br />River. In addition, studies were also performed to determine the addi tional <br />travel time of releases from Turquoise lake and Clear Creek Reservoir to the <br />Pueblo gaging,station, the Bessemer Ditch, and Colorado Canal headgate. <br /> <br />Theoretical methods of estimating travel time on the Arkansas River were <br />investigated, including flood routing, and were found to be inadequate. Em- <br />pirical data based on past records of river flow and physical observations <br />and measurements were used to develop time of travel relationships. A nomo- <br />graph, Figure IV-I, was developed that can be used for administrative purposes. <br />This nomograph correlates the time of travel of the first observable changes <br />in stage of the release and shutoff of the reservoir run from Twin lakes to <br />the Colorado Canal. It also shows travel time from Twin lakes to the Pueblo <br />gaging station and the Bessemer Ditch. The nomograph includes adjustments <br />so that travel time to the Colorado Canal and other points can be estimated <br />from Turquoise and Clear Creek Reservoirs. <br /> <br />DATA <br /> <br />Original data used in preparation of this report includes analysis of <br />the original gaging station records of the Granite, Salida, Canon City, Pueblo <br />and Nepesta gages from 1966 through 1970. Also studied were the original <br />gaging station records at lake Creek above and below Twin lakes Reservoir. <br /> <br />Over 150 gate openings, release adjustments, and shutoffs occurred dur- <br />ing this 5-year period involving the 3 upper Arkansas reservoirs. Uften two <br />or more reservoirs were running water at the same time usually opening and <br />closing the reservoi r gates at different times, thus making the runs overlap. <br />In most caseS distinct "reservoi r run" hydrographs could not be followed down <br />the river using the gaging station charts. About 25 releases were found that <br />did give distinct "reservoir run" hydrographs that were not obliterated by <br />other releases, rain and general fluctuation in the stream flow. The front <br />portion of the releases and the tail end or shutoff of the reservoir were <br />studied separately. In addition, many salient features of the river hydro- <br />graph were studied as they appeared on the gaging station charts. These <br />bumps or depressions on the hydrograph could have been caused by various <br />phenomena, such as a short, intense rainfall in the upper basin, a brief <br />change in the reservoir release rate, etc. <br /> <br />Observations of 20 temporary river-stage stations made during the May <br />2, 1970 run, by this office and the State Engineer's Office, were also used <br />in analyzing the flow time. A summary of the field data collected on the <br />May 2, 1970 reservoir release is presented in the Appendix. These tempor- <br />ary river-stage stations consisted of staff gages installed by our office <br />in the river. Data was then recorded so that the shape and time of arrival, <br /> <br />27 <br />