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Table 5.1. Summary of rating curve coefficients (Qs=aQ~ Gage Total Suspended Sand Wash Load wad Load Load a b a b a b a b Mayben NA NA NA NA Lily 5.37e-2 1.62 0.0447 1.64 0.028 1.64 Deerlodge 3.168 1.02 12.58 0.88 3.498 0.91 0.557 1.16 Mathers 0.379 1.26 0.381 1.26 1.57e-4 2.01 3.61 0.951 Jensen (pre-dam) 6.100-3 1.7 3.38e-7 2.62 2.100-4 1.88 (Post-dam) 1.72e-2 1.58 2.04e..5 2.16 5.03e-6 2.26 Note: Deerlodge and Mathers coefficients are bias corrected and were derived using data for discharges greater than 2000 cfs. Deerl0d2e Park G8ie The USGS (Elliot, et al., 1984) defined rating curves for the Deerlodge Park gage based on data colJected in 1982 and 1983. The rating curves were prepared for total sediment load, as well as various components of the total load. Since the published report included the measured data, it was possible to derive the bias correction coefficients. Application of the bias correction caused some inconsistency in the rating relationships. The bias correction tended to over correct for the expected underprediction of the mean value (see Table 5.2). Additionally, the bias corrected suspended load rating curve plotted above the total load rating curve, which did not occur with the uncorrected rating curves. Review of the raw data indicated that there was a noticeable break in the data set between about 1000 and 2000 cfs, with a smalJ cluster of points in the 1000 cfs range and a larger cluster of points above 2000 cfs. With bias correction analysis based only on the upper cluster of points, more consistent rating relationships resulted for the higher flows. Given that the transport rates were typically very low in the lower cluster, and that the flows of significance in sediment transport are typically the higher flows, regression on only the higher flows was justified. Figure 5.2 illustrates the fit of the various rating curves against the raw data, and the preferred coefficients for use in computation of effective discharges are summarized in Table 5.1. Table 5.2 Results of bias correction analysis for Deerlodge Park. Raw Original Corrected aa Data No Obs. Mean of R"2 Correction Mean of Os Mean n a b Pred. Coef. C a b Corr. Val. TOTAL LOAD Plows 0> 2000 36182 26 2.609E+OO 1.0198 3OS03 0.420 1.2141 3.168E+OO 1.0198 37032 All Plows 30653 31 2.916E-01 1.2585 26652 0.787 1.2043 3.511E-01 1.2585 32fN7 SUSPENDED LOAD Plows Q > 2000 3SS5O 27 9.5S6E+OO 0.8750 19768 0.291 1.3168 1.2S8E+01 0.8750 37614 All Plows 293S2 33 1.254E-01 1.3490 24902 0.757 1.4299 1.193E-01 1.3490 36119 SAND LOAD Plows Q > 2000 14154 26 2.937E+OO 0.9092 12310 0.389 1.1913 3.498E + 00 0.9092 14664 All Plows 11939 31 1.678E-02 1.4712 1113S 0.808 1.2500 2.097E-02 1.4712 13918 WASH LOAD Plows Q > 2000 21212 26 3.301E-01 1.1642 12694 0.271 1.6878 S.572E-Ol 1.1642 24015 All Plows 18129 31 4.879E-Ol 1.1220 10787 0.562 1.7022 8.30SE-01 1.1220 20729 5-6 I I I I I I I I I I I I I I I I I I I