|
17,000
<br />46,000
<br />15.000
<br />13,000
<br />42,000
<br />11,000
<br />10,000
<br />9,000
<br />8,000
<br />LL 7,000
<br />6,000
<br />5,000
<br />4,000
<br />3,000
<br />2,000
<br />1,000
<br />If
<br />NO BREACH OUTFLOW HYDROGRAPHS
<br />FROM EACH CONTRIBUTING BASIN
<br />AND COMBINED FLOWS
<br />12
<br />— West Fork of Litt Thompson River, Meadow Dam Basin
<br />— Little Thompson River Basin Upstream oFUS 36
<br />— West Fork of Little Thompson River9asin, Meadow Lake to US 36
<br />— Little Thompson River, US 36 to North Fork
<br />— North Fork Basin
<br />Rowell Gulch Basin
<br />— Little Thompson River. Total outflow Near X Bar? Subdivision
<br />L9 , , . , , , , 1�
<br />Sep2013
<br />Figure 21—No Breach model outflow hydrographs for each contributing basin and combined total outflow
<br />(corresponds to model data shown in Table 10).
<br />11.2 Dam Breach Model Results
<br />Once parameters for the no- breach model were calibrated to produce reasonable results relative
<br />to estimated flows at the calibration cross - sections, the model was run with the same rainfall and
<br />runoff scenarios, but with dams set to breach at their established failure times. Table 11 shows
<br />results of that model run.
<br />Table 11— Dam Failure Model Results
<br />Comparison of Table 11 information depicting the timing of the failures, with the information in
<br />Table 10 showing the timing of the peak discharges from each basin and cross - section of interest
<br />reveals that only Sunset dam failed approximately 3.5 hours after the peak discharge from the
<br />basin. This relationship of dam failure to peak inflow is also shown below in Figure 22. The Sunset
<br />dam failure occurred on the falling limb of the inflow hydrograph between periods of intense rain.
<br />Due to the size of the contributing basin (14.92 sq mi) and overwhelming volume of the inflow, the
<br />Report of the September 2013 Little Thompson River Flooding COLORADO
<br />and Big Elk Meadows Dam Failures, June 2014 (Revised, Dec 2014) * Division of Water Resources
<br />Page 31 of 48 b pirr ent or r.alurar $esroixre:
<br />DAM SAFETY BRANCH
<br />Time of Dam
<br />Inflow at Time
<br />Time of Dam Failure
<br />Peak outflow due
<br />Increase in flow
<br />Dam
<br />Failure
<br />of Failure (cfs)
<br />Peak outflow
<br />to Failure (cfs)
<br />due to failure (cfs)
<br />(MDT)
<br />Sunset
<br />9/12/13, 7:40 AM
<br />2,132
<br />9/12/13, 8:00 AM
<br />2,535
<br />403
<br />Rainbow
<br />9/12/13, 12:25 PM
<br />2,282
<br />9/12/13, 12:45 PM
<br />3,790
<br />1,508
<br />Willow
<br />9/12/13, 12:05 PM
<br />2,374
<br />9/12/13, 12:25 PM
<br />3,151
<br />777
<br />Mirror
<br />9/13/13, 2:00 AM
<br />1,224
<br />9/13/13, 2:20 AM
<br />1,706
<br />482
<br />Meadow
<br />9/12/13, 1:40 PM
<br />2,444
<br />9/12/13, 2:00 PM
<br />4,419
<br />1,975
<br />Comparison of Table 11 information depicting the timing of the failures, with the information in
<br />Table 10 showing the timing of the peak discharges from each basin and cross - section of interest
<br />reveals that only Sunset dam failed approximately 3.5 hours after the peak discharge from the
<br />basin. This relationship of dam failure to peak inflow is also shown below in Figure 22. The Sunset
<br />dam failure occurred on the falling limb of the inflow hydrograph between periods of intense rain.
<br />Due to the size of the contributing basin (14.92 sq mi) and overwhelming volume of the inflow, the
<br />Report of the September 2013 Little Thompson River Flooding COLORADO
<br />and Big Elk Meadows Dam Failures, June 2014 (Revised, Dec 2014) * Division of Water Resources
<br />Page 31 of 48 b pirr ent or r.alurar $esroixre:
<br />DAM SAFETY BRANCH
<br />
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