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<br />data set. The "Post '81" curve does more closely mimic the "Pre-Dam" curve in the 10% to <br />50% range. <br /> <br />Historic Sediment Information <br /> <br />During the first stage of the study, suspended sediment data from John Martin Reservoir <br />sedimentation reports were analyzed. Relatively long-term records of discharge-suspended <br />sediment exist for the Arkansas River at Las Animas, and below John Martin Dam, as well as <br />the Purgatoire River at Las Animas gage stations. The records for both of the Arkansas River <br />locations covered the period of October 1942 to March 1972. The Purgatoire River period of <br />record was July 1948 to March 1972. <br /> <br />Mathematical analyses were performed for each of these locations and the results <br />plotted. The analyses consisted of entering the values into a spreadsheet program, performing <br />unit conversions to arrive at water discharge in cubic feet per second (cfs) and suspended <br />sediment discharge in tons per day (ton/d), elimination of zero discharges, sorting, and finally, <br />correlation analyses of the logs (base lO) of the water versus the suspended sediment <br />discharges. These analyses were performed for the entire data sets, as well as by months. Table <br />3-1 provides information on the success of the mathematical representations. The figures in <br />Appendix A show the scatter data and linear relations. <br /> <br />Table 3-1. Correlation (R2 values) of discharge versus suspended sediment. <br /> <br />Time Period <br />January <br />February <br />March <br />April <br />May <br />June <br />July <br />August <br />September <br />October <br />November <br />December <br />Aggregate <br /> <br />Arkansas River at Las <br />Animas, CO <br />0.85 <br />0.86 <br />0.92 <br />0.75 <br />0.88 <br />0.90 <br />0.77 <br />0.81 <br />0.65 <br />0.90 <br />0.94 <br />0.95 <br />0.85 <br /> <br />Purgatoire River at <br />Las Animas, CO <br />0.77 <br />0.79 <br />0.80 <br />0.82 <br />0.82 <br />0.88 <br />0.78 <br />0.84 <br />0.90 <br />0.89 <br />0.77 <br />0.77 <br />0.86 <br /> <br />Arkansas River below <br />John Martin Dam, CO <br />0.72 <br />0.52 <br />0.78 <br />0.34 <br />0.05 <br />0.02 <br />0.05 <br />0.01 <br />0.00 <br />0.l8 <br />0.55 <br />0.6l <br />0.69 <br /> <br />l4 <br />