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<br />
<br />The frequency discharges at these sane loc~tions for the IOO-year
<br />event without Douglas Reservoir are shown in Table IV. The
<br />percentage increase in flow for this basin c~ndition is also shown,
<br />indicating a 15%-20% increase in the nagnitude of the flood peak if
<br />a bypass channel were constructed to direct all drainage flows around
<br />Douglas Reservoir. This impact in Fort Collins is significant, not
<br />only from increased flood peaks but also that larger magnitude drainage
<br />flows would be mo=e f~cquer.t and flood volumes could be considerably
<br />greater.
<br />
<br />'I'able IV
<br />
<br />Effect of Dougl~s Reservoir
<br />on IOO-Year Peak Discharge
<br />
<br /> With Dougl~s WithO\;.t Douglas Percent of
<br />Location Reservoir (ch) Reservoir (cfs) Increase
<br />Confluence with 27011 J~OO "
<br />"Paudre
<br />Dls of Caton Ditch 2900 3400 "
<br />t:/S of Eaton Ditcll 2')()0 3400 15
<br />C. S. Highway 2S7 2900 3400 15
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<br />The hydrograph in Figure 3 shows an early, secondary flood peak that
<br />is generated from runoff on im?erviolis areas in the lower Dry Creek
<br />basin. ,"lood plain improvement alterniltives such as channel Jiversiolls
<br />or flood detention up"tr",am of t.he T,,3rimer-~:eld C.lnal would not elininatc
<br />the need to provide facilities to convey this localized drainage.
<br />
<br />-15 -
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