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<br />CONTENTS
<br />
<br />Abstract ..
<br />Introduction ........
<br />Acknowledgments
<br />The setting ..
<br />History of the dams ...
<br />LawnLskedam.... .........
<br />Possible causes of failure . . . . . . . . . . . .
<br />Cause of failure ........
<br />Cascade Lake dam ..
<br />Cause of failure ..................
<br />Hydrologic analysis of the flood .' .
<br />Flood data. .. . . . . . . . . .. . . .. . . . . , . ...
<br />Station descriptions and streamflow data ...
<br />Peak stages and discharges . . . . . . . . . . .
<br />Volume ...............,..................,
<br />Velocities, depths, widths, and areas ...........
<br />Flood profiles. and boundaries
<br />Flood frequency .. .. .. .. .. .. .. ..
<br />Traveltime ......... ........
<br />Description of f1ood~wave charactl31'istics .............
<br />Roaring River: Lawn Lake darn to Horseshoe Falls . . .
<br />Fall River: Horseshoe Falls to Cascade Lake dam . . . .
<br />Fall River: Cascade Lske dam to Estes Park powarplant
<br />Fall River and Big Thompson River: Estes Park powerplant
<br />to Lake Estes. . .. . . . . .. . .. .. . .. . . . .. . . .. .. .
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<br />P...
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<br />Geomorphic effects of the flood ..... . . . .
<br />Roaring River: Lawn Lake dam to Horseshoe Falls . . .
<br />Roaring River alluvial fan ...
<br />Fall River: Horseshoe Falls to Cascade Lake dam _ _ . .
<br />Fall River: CasCade Lake dam to Estes Park powerplant
<br />Catastrophic flood features .......
<br />Fall River and Big Thompson River: Estes Park powerplant
<br />to Lake Estes
<br />Sediment in Lake Estes
<br />Dll1ll-breakmodeling ... ................
<br />Dam,break model ... . . , . . . . . . . . . .
<br />Data requirements and assumptions ..' . . . . . . . . . .
<br />Model calibration ...... ..,....,
<br />Model simulations . . . . . . . . , .
<br />Variations of Lawn Lake dam breach width and tim.
<br />ing ..,.... ...........
<br />Effects of Cascade Lake dam failw-e ..,.....,..
<br />Discussion of results ... ".",.. .
<br />The flood aftermath .......
<br />The human element. , .......... , .. . ' .. .. . . . .. .. .
<br />The damage .
<br />Summary and conclusions
<br />Gaging-station and miscellaneous-site data ' . . , , . . . . . . . . ,
<br />References ,..,...,.... ...,.........
<br />Supplemental cross-section data. . . . . . , . . . , . . . , , . . . . . . ,
<br />
<br />29
<br />
<br />ILLUSTRATIONS
<br />
<br />PLATE 1.
<br /> 2.
<br />FIGURE 1.
<br /> 2.
<br /> 3-10.
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<br />p...
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<br />p...
<br />
<br />Map showing topography of Lawn Lske before and after flood of July 15, 1982, Rocky Mountain National Park,
<br />Colorado ................................................................................ In pocket
<br />Map showing topography of Cascade Lake hefore and after flood of July 15, 1982, Rocky Mountain National Park,
<br />Colorado .........,................................................ ................. In pocket
<br />Location map of area between Lawn Lake dam and Lake Estes ... , . . , . . . . . . . , . , , , . . , , . . . . , . . . , . . 3
<br />Graph showing long profile of the flood path of the water from Lawn Lake dam and Cascade Lake dam failures 4
<br />Photographs showing:
<br />3. Lewn Lake dam and reservoir prior to failure (July 11, 1958) (aerial) . . . . . . . . . . . . . . . . . . 6
<br />4. The top of Lawn Lake dam, prior to failure and after failure . . . . . . . . . . . . . . . . . . . 7
<br />5. The cross section of Lawn Lake dam following failure "................ " .. . .. . .. .. . .. 8
<br />6. The remains of the outlet valve from Lawn Lake dam .. .. .. . . . .. .. .. ... . . . . . . . . .. . ... .. . .. . . . 9
<br />7. The downstream face of Lawn Lake dam prior to failure and the front of Lawn Lake dam following failure 10
<br />8, Empty Cascade Lake prior to failure. View ia towsro upstream face of dam (date unknown) ........... 11
<br />9. Cascade LaI<e dam, before, during, and following failure. . . . . . . . . . . . . . . .. . . . . . . . . . . , . . . . . . . . . . 12
<br />10, The middle teach (river mile 2.1) of the Roaring River showing the extensive areas of scour and fill along the
<br />channel .........,.... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
<br />11. Graph showing peak-diacharge profIle based on indirect peak-discharge measurementa and model results . . . . 17
<br />12. Photograph showiIlg Lawn Lake about 1 week after the d8D1 failure, showing the amount of water still remaining in
<br />the natural depression forming the original lake (aerial) ...,.. . . . . . . . . . . . . . . . . . . . 19
<br />13-15, Graphs showing:
<br />13. Flood-frequency curves at station 06733000 Big Thompson River at Estes Park, 1951-77 . , 21
<br />14. Regional flood-frequency curve for Roaring River at Horseshoe Falls, based on regional regression equation of
<br />McCain and Jarrett (1976) ............ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
<br />15. Arrival time, peak time, and traveltime of leading edge of flood wave of July 15, 1982 ....,.... 25
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<br />III
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