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<br />comparing peak runoff to land areas above 10,000 feet in elevation. Areas above <br />10,000 feet in elevation were chosen as being representative of snowpack areas that <br />contribute significantly and almost entirely to peak runoff events. Visual observation of <br />runoff patterns, as well as Sno-Tel data collected by the NRCS indicates that most <br />snowpack below 10,000 feet is nearly if not fully melted by the time peak runoff occurs. <br /> <br />. Areal analysis was attempted by utilizing the Watershed Modeling System developed by <br />Brigham Young University. This software is intended to use Digital Elevation Models <br />produced by the USGS. The purpose in using the model was to rapidly produce <br />regression analyses of peak flows vs. tributary areas vs. various elevations. However, a <br />unexplained error in the subroutine that calculates areas between two contours rendered <br />the software unusable for this purpose. Thus, areas above 10,000 feet elevation were <br />determined by planimetering 1 :50000 scale USGS Eagle County series maps. <br /> <br />Figure 5 graphically shows areas above 10,000 feet elevation. Additionally, a statistical <br />analysis of areas above 10,000 feet vs. peak runoff further validates this observation <br />(Figures 6-9), with extremely high ~ values of 0.97 to 0.98. <br /> <br />CONCLUSIONS <br /> <br />Based on the excellent correlation between peak runoff and the area / elevation <br />regression analysis (r2 values of 0.97 to 0.98), the equations shown on Figures 6 through <br />9 were used to determine peak flows at various points along the Eagle River. Table 10 <br />summarizes the flows based on the areally based equations; previously reported FEMA <br />flows, and flows calculated from Log Pearson Type III analysis of gage records. <br /> <br />Table 1 in the Executive' Summary provides flow values for the Eagle River and <br />Colorado River. Where flows did not vary by more than 10 percent from flows previously <br />reported by FEMA, previously reported values are shown in Table 1, along with the <br />reference for the source of the data. <br /> <br />13 <br /> <br />~ <br /> <br />Water Resource Consultants, LLC <br />.....l <br />