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at or near critical depth is an acceptable assumption (NRCS, 2013) and appeared appropriate in <br />this study. Table 8 summarizes the estimated peak flows at each indirect measurement location <br />from Dam Safety Branch surveys and also taken from the referenced studies. If should be noted <br />that the methods used in the referenced studies vary as do the locations of the measurements. <br />Figure 16 shows the locations of indirect flow measurement sections. Location maps showing Way <br />Point (WP) designations, reduced survey data, and details of the peak flow estimate computations <br />are presented in Appendix B. <br />Table 8 — Indirect Flow Estimates at Calibration Cross Sections <br />Location of Indirect Measurement (Source) <br />Estimated Peak <br />Flow (cfs) <br />West Fork Little Thompson River, Upstream of <br />3,657 <br />Sunset Lake (WP60) <br />West Fork Little Thompson River, Upstream of <br />4,056 <br />Sunset Lake (WP27) <br />Deer Creek, Upstream of Meadow Lake (WP 29) <br />1,764 <br />West Fork Little Thompson River, Downstream <br />4,201 <br />from Meadow Lake (WP20) <br />West Fork Little Thompson River, Downstream <br />6,215 <br />from Meadow Lake (WP21) <br />Little Thompson River, Upstream of confluence <br />2,420 <br />with West Fork (WP62) <br />Little Thompson River, Near Pinewood Springs <br />(NRCS, 2013) <br />14,600 <br />Little Thompson River, Near X Bar 7 Subdivision <br />15,731 <br />11 FINAL MODEL RESULTS <br />Table 9 shows comparison of the estimates of flow at those selected cross sections as compared to <br />those from the final HEC -HMS model. Exact calibration at all cross - sections is not a realistic <br />expectation given the complexity of the physical processes of this rainfall, runoff and flooding. <br />Some tradeoff between upper basin correlation and lower basin correlation was considered <br />acceptable in order to maintain all correlations within an acceptable range. <br />Two models were run for this study: (1) the model run assuming no dams breached during the <br />rainfall which provides the basis of the flows, timing of the peak discharges from each contributing <br />basin and provides a sense of potential impacts to existing structures and facilities downstream of <br />the Big Elk Meadows assuming no dams breached during the storm, and (2) The HEC -HMS model <br />was configured with the overtopping breach parameters previously described, and the model set <br />to breach the dams at the trigger (dam failure) times established. Results of the model including <br />Report of the September 2013 Little Thompson River Flooding COLORADO <br />and Big Elk Meadows Dam Failures, June 2014 (Revised, Dec 2014) A&V Division of Water Resources <br />Page 27 of 48 - - <br />■ 9go VM:1ovilH41:1 <br />