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<br />I <br /> <br />DRAFT <br /> <br />20 llirkansas River from John Martin Dam to COIKS State Line <br />Channel Capacity and Riverine Habitat Planning Study <br />Planning Assistance to States <br /> <br />Under the Planning Assistance to States program, the Albuquerque District Corps of Engineers office <br />undertook a study to detennine possible improvements to the channel capacity and riverine habitat <br />of the Arkansas River between Jolm Martin Dam and the ColoradolKansas border. Channel capacity <br />improvements are intended to allow more efficient water deliveries and/or reduced maintenance. <br /> <br />The study was addressed in two stages: 1) Assembly of Historic Information, 2) Hydraulic and <br />Sedimentation Analysis. <br /> <br />Hydrologic Issues <br />During the first stage of the study the historic flow data for the Arkansas River below was evaluated <br />to some extent. This historic information was .obtained from the United States Geological Survey <br />(USGS) web site and imported into a spreadsheet program. The data set covers the period from <br />April I, 1938 through October 3l, 1995, though the data has been gathered from three separate sites <br />over that time. The three sites are all within two miles of each other with no significant tributary <br />inflow within that distance and are comparable. <br /> <br />The data set was divided into two parts; April 1, 1938 to September 30, 1942, and April 1, 1943 to <br />October 31, 1995. <br /> <br />Sediment Issues <br />During the first stage of the study, suspended sediment data from Jolm Martin Reservoir <br />sedimentation reports was analyzed. Relatively long term records of discharge-suspended sediment <br />exist for the Arkansas River at Las Animas, CO and below John Martin Dam, CO, as well as the <br />Purgatoire River at Las Animas. The records for both of the Arkansas River locations covered the <br />period of October 1942 to March 1972. The Purgatoire River period of record was July 1948 to <br />March 1972. <br /> <br />Mathematical analyses were performed for each of these locations and the results plotted. The <br />analyses consisted of entering the values into a spreadsheet program, perfonning unit conversions to <br />arrive at water diScharge in cubic feet per second (cfs) and suspended sediment discharge in tons per <br />day (ton/d), elimination of zero discharges, sorting, and finally, linear regression analyses of the logs <br />(base 10) of the water vs. the suspended sediment discharges. These linear regressions were <br />performed for the entire data sets, as well as by months. Table I. provides information on the success <br />of the mathematical representations. Figures I through 39 show the scatter data and linear relations. <br /> <br />The linear correlations and graphical representations indicate an apparent change in the suspended <br />sediment transport characteristics of the Arkansas River as a result of Jolm Martin Dam. This is <br />expected, since part of the benefits of a reservoir are often retention of sediment. The Sedimentation <br />in Jolm Martin Reservoir, Arkansas River Basin, Colorado, Resurvey of March 1972 report states <br />a calculated trap efficiency of 87.5%. The change, however, is more complex than a simple reduction <br />of suspended sediment. While the aggregate data and linear representations are relatively well- <br /> <br />~~. ..~. -.'- <br />~,..-,c'" ~ <br />U;;<Li-~~~" jj <br />