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<br />. <br /> <br />,.... ...~ ,.- ,~ <br />~U.j(.t <br /> <br />It is recommended that an annual rate of 0.130 acre-feet per square mile of contributing <br />drainage area be used for projecting sediment accumulation in Pueblo Reservoir. This value <br />was determined using the 29.9-year annual rate for John Martin Reservoir and the 19.3-year <br />annual rate for Pueblo Reservoir. This value will be better defined in the future after each <br />survey of Pueblo Reservoir. <br /> <br />The results of the sediment data and volume computations forthe 1993 survey are shown in <br />tables 1 and 2. The data include a tabulation of incremental sediment inflow volume and <br />sediment accumulation computed for the period between initial conditions and the 1993 <br />resurvey. Table 1 includes information on the drainage basin, records of estimated inflow, <br />reservoir operations, and reservoir storage. <br /> <br />RESERVOIR SEDIMENT DISTRIBUTION <br /> <br />Longitudinal Distribution <br /> <br />The distribution of sediment throughout the length of the reservoir is illustrated by plots of <br />the thalweg profile representing the original and 1993 resurveyed proflles for the Arkansas <br />River as shown on figure 7. Thalweg elevations representing original and resurveyed <br />reservoir conditions were taken from the original and 1993 survey notes. Except for the <br />possibility of somt; missed low points, the plotted proflle should closely resemble actual <br />channel bottom conditions during the original range survey completed prior to inundation of <br />the reservoir. Except for some minor inaccuracies in sounding and being slightly offline, the <br />bottom of the 1974 and 1993 profiles should closely represent channel bottom conditions at <br />the time of those resurveys. The channel distance used for range line location is the original <br />river channel distance from the dam to each range line in an upstream direction on the <br />Arkansas River. <br /> <br />Lateral Distribution <br /> <br />Ground profiles for the 31 original sediment ranges are shown on figures 8 through 38. The <br />survey data were obtained from copies of the original survey data books. Several of the lines <br />had portions resurveyed prior to reservoir inundation to account for borrow pit areas. The <br />original data used for the sedimentation analysis accounted for the borrow pit areas. The <br />1993 range profile data are superimposed on these plots to indicate the changes which have <br />occurred and to represent in general the lateral distribution of sediment within the reservoir. <br />A 1993 survey was not accomplished for range lines 17, 18, and 70 because they were located <br />upstream from elevation 4900.0, and no reservoir deposition was judged to have occurred <br />above that elevation. For sediment computation purposes, a complete section was needed for <br />all ranges; for this reason, the original data were inserted into the 1993 data file to complete <br />the areas not surveyed in 1993. <br /> <br />6 <br /> <br />_L <br />