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<br /> Table 10 <br />User Gage Weighting, 5-6 September 1970 <br />:\Iost Upstream to :\lcPhee Dam <br />Precipitation (inches) <br />Subbasin Drainage Area Depth <br />Name (sqmi) (inches) <br />West Fork Dolores 168 3.0 <br />Dolores Ilcadwaters 105 3.2 <br />Dolores Uppcr Mid 65 2.2 <br />Bear Creck 34 2.3 <br />Dolores ~1 id 74 3.0 <br />Dolores Lowcr 57 2.2 <br />Dolores Out I 2.2 <br />Lost Canyon Creek 71 3.0 <br />Lost Canyon Creek Out 3 2.5 <br />Dolores Lower Out 1 2.3 <br /> <br />6.9 Model Validation for Flood Simulation. The validity of the upper Dolores Rivcr <br /> <br />basin HMS model developed for this Ilood insurance study was tcsted by using it to reproduce the <br /> <br />September 1970 high flow event on the watershed. Thc IIMS modc1 was run for the 1970 stann, <br /> <br />using thc subbasins, unit hydrographs, loss rates, basetlow, Muskingum routing parameters. 2-day <br /> <br />stann isohyetal map amI hourly prccipitation distribution discussed above. A comparison <br /> <br />between the output '.computed hydrograph" and the observed hydrograph for the 1970 flood at <br /> <br />the Dolores gage is presented graphically on Plate 10. Thl.': two hydrographs are tabulated in <br /> <br />Appendix A, Tablc 4. Since an observed hourly hydrograph for the East Fork belO\v Rico gage <br /> <br />was not available for comparison, the peak 1100v and threc-day volume \verc compared. Table II <br /> <br />presents a comparison of computed and observed pcak Ilows and volumes at Ihc Rico and Dolores <br /> <br />gages. The Septembcr 1970 rainllood peak at Dolores was aNHlt a 4% I.':vcnt. The unit <br /> <br />hydrograph and streamflow routing paramcters used for the 1970 flood calibration \Vere not <br /> <br />changed for the t% rainflood simulation because a change in thc rcsults would be ncgligible. The <br /> <br />HMS model is assumed suitable for computing I % chance flood hydrographs for this study. <br /> <br />23 <br />