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<br />6.2 Concurrence wilt/1 Windsor FIS Profiles <br />Upstream of cross secticn 50 (station 101911), the hydraulic model used I(lr the current <br />effective FEMA studies near Windsor begins just downstream of Weld County Road 23. The <br />water surface profiles for the C2.che la Poudre River in thi:; area are published in the Weld <br />County FlS. The first several cross sections of the Windsor bydraulic model were added to tbe <br />hydraulic model and the river flows and roughness values in tbat part oftbe hydraulic model <br />were set 10 those used in the Witldsor hydraulic model. <br />Water surfae:e profiles computed for this study were compared with those published in <br />th~ Weld County FIS for the Cache la Poudre River near Windsor. At cross section "A" <br />(103250) of the FrS, the I OO'.year computed water surhe:e elevation was about one [<JOt lower <br />than the published elevation. At cross section "BOO (10:;670), the I DO-year computed water <br />surface el.evation was less than half a foot below the: publdlcd elevation. At cross section "C' <br />(105810), the I DO-year flood w,ter surface elevation computed for this study and the published <br />value were about the same. <br />T1e starting water surface elevations for the FEMI\ studies at Windsor were computed <br />using the slope-area method ofHEC..2 at a cross section about (lOO feet downstream ofFIS cross <br />seGtion "A". It appears that this resulted in computed waler surface elevations that were too high <br />at cross s'~ction "A". The hydraulic model for this study provides much better starting conditions <br />for the Windsor reach than that used in the original study ,md should replace the current FrS <br />starting elevations. <br />7.0 FLOOD BOUNDARIES <br />Flood boundaries for the IOO..year and SOD-year [leods were developed at each cross <br />se,:tions based on the computed water surface elevation s al each cross section and the ground <br />elevation> at the crm:s sections. Between the cross sections. the flood boundaries were <br />established using flood elevations interpolated from the waler surface profile plots and the <br />topographic mapping. The final flood boundary maps were delineated by the City of Greeley on <br />the Geographic Information System. The flood boundaries are shown on Plates I through 6, <br /> <br />7 <br />