|
<br />.' .~...
<br />
<br />;,:,,'.'"
<br />
<br />'.-
<br />
<br />
<br />,,-,:.
<br />
<br />
<br />':('.:,~:: ,
<br />.".',
<br />
<br />.~' ". ~
<br />
<br />\>. ,::'
<br />'., '
<br />.' ,~:: .
<br />';",\.~"::
<br />
<br />~:~.)\::
<br />:.:",-:'- ~~
<br />"
<br />':.:'('"
<br />\.,:' .
<br />
<br />',;"
<br />
<br />",
<br />'\.'
<br />
<br />, .
<br />
<br />::'1'
<br />
<br />.' ..,.."
<br />",' \'...
<br />:, ":)<,~W':'~?'
<br />'.".:
<br />
<br />'-.~~-~:~'~~l~~
<br />
<br />000089
<br />
<br />',.
<br />
<br />of 329,000 acre-feet, and a maximum l4-day volume of 438,000
<br />"ere-feet. Plste 8-2 shows the operational and flood hydrographs
<br />Rnd reservoir sta~e for the maximum probable peak inflow flood.
<br />
<br />.,";
<br />,
<br />
<br />a-o). Standard Project Flood. The runoff from the June 1921
<br />storm was found to be of standsrd project flood ma~nitude. Fur
<br />the original studies of the flood control requirements at Pueblo
<br />Dam and Reservoir, it was determined thst an increase of 50 per-
<br />cent in the 1921 flood hydrograph, ss it occurred, would be
<br />'equivalent to the standard project flood. Ouring subsequent
<br />studies for the "Report on Review Survey for Flood Control and
<br />Allied Purposes, Arkansas River and Tributaries above John Martin
<br />Dam, Colorado," it was further determined, from a transposition
<br />of the June 1921 storm, that the standard project flood volume
<br />would be about 50 percent more than the June 1921 flood as it
<br />occurred. Also, the peak discharge from this transposition would
<br />be about twice that of the actual flood or l70,OOO c.f.s. In
<br />obtaining the standard project flood operational hydrograph,
<br />it was assumed that an sntecedent flood equal to one-third of
<br />the standard project flood occurred 5 days priur to the standard
<br />project flood. The standard project flood hydrograph has a peak
<br />flow of 170,000 c.f.9. snd a volUl1lll of 140,000 acre-feet. When
<br />the standard project flood with antecendent flood was routou
<br />through the reservoir, the IDlIximum flood volume stored was Ilfl,900
<br />acre-feet (ll4,100 acre-feet from the standard project flood),
<br />USing 25,900 acre-feet of surcharge storage, and the peak outflow
<br />was 17,200 c.f.s. at the maximum pool elevation 4903.2 feet mal.
<br />Plate 8-3 shows the routing criteria used, operational hydro-
<br />graph, flood hydrograph, and reservoir stage.
<br />
<br />8-04. Deaign Flood. The June 1921 flood produced a peak flow
<br />of 87,000 c.f.s. and a volume of 93,000 acre-feet at the Pueblo
<br />Dam. The volume is equal to .38 inches of runoff from the
<br />4,670 square milea of drainage area. This flood was selected
<br />as the hasis of deSign for the flood control storage. at the
<br />Pueblo Reservoir. The volums of the flood hss a recurrence
<br />interval of about 100 years. Flood control storage in the Pueblo
<br />Reservoir, in conjunction with the existing Pueblo Floodway,
<br />provides the city of Pueblo protection against Arksnsas River
<br />floods exceeding the standard project magnitude. The total fluod
<br />runoff of the desir,n flood wss stored without releases during the
<br />period of inflow. PlAte 8-4 shows the operational hydro graph and
<br />drawdown curve of the design floo.l.
<br />
<br />, I
<br />
<br />~\-05. Frequencies. The I'i>llximum annual discharge-frequency curves,
<br />initial condition, shown On Plate 8-5, represent the probable flows
<br />above and below the Pueblo Dam. Plate 8-6 presents the pool ele-
<br />vation frequency and duration curves, initial condition. The end-
<br />of-month water surface elevations, 50-year sediment conditions,
<br />
<br />8-2
<br />
<br />'.,-"
<br />
<br />
<br />','.,
<br />
<br />.;. . t ':'.:-:,<~'~'{~~.;,{(/ ': .'..
<br />
<br />.".-.-
<br />
<br />. c.'....
<br />''',..;".',
<br />,.,..
<br />
<br />':. .
<br />
<br />':':'~' ': \
<br />",~ ' ,'.,
<br />
|