Laserfiche WebLink
<br />Poudre River basin ~hlch meet this criteria are Fosail Creek near Fort <br />Collins and Sheep Dra~ near Greeley. Local interests also asaigned <br />these sUeams pdo-.:-ity for study. Volu!l\t) III of the Special Study <br />covers Sheep Ora~ and Volume IV cov~rs Fossil Creek. The locatlnns of <br />these Msins are sho~n on plate L <br /> <br />The p-.:-esent study was based on n..~ topographIc ",".pping and cros" <br />"ectlons taken at closer Intervals than In the Flood Insurance Study <br />(FIS). Also, the study reach on Sheep Draw ~as e~tended farther <br />upstream than In the fIS which ended at U.S. Rlgh~ay 34. In thIs <br />study, the EnvIronmental Proteetlon Agency's (ErA) Stor~ater Manage- <br />ment Modei (SWMM) ~a9 used to determIne flood dlscharges. Peak <br />dischargea for floods of vadoua fre'luency were cOlllputed uslng the U.S. <br />Soil Conservation Service (SCS) Technical Release No. 20 computer <br />program In the FIS. The 100-year flood discharge for the prescnt study <br />averages about 90 percent of the discharge used in the FIS. Downst-.:-eam <br />from County Road 29 (7lst Avenue), the 10o-year floodwater surface <br />profile for the pr~geRt study generally ranges frOlll I to S feet higher <br />than in the FIS with the depth variations increasing in the. downatresllI <br />direction. Upstream from County Road 29, the IOO-year flood profile in <br />the present study generally varies less than a foot nbove or below the <br />IOo-year profile in the FIS. <br /> <br />HydrologIc modeling studies ~ere conducted to determine the peak <br /><ii"charges for floods of various p-.:-obabUiUes of occurrence. This <br />information was developed first for existing watershed land use. To <br />determine the effect of increasing urbanl~atlon on flood runoff, <br />possible future urban land uSe was superimposed on the Sheep Draw <br />OOa[n. Volu",-e tI of this study presents del ~lls of the hydrologic stud- <br />ies. Hydraulic modeling studies were conducted to develop the flood <br />water surface profIles and flood piain boundaries. Flood profiles are <br />sho\fU for existing and future conditions_ flooded arcn ~~p8 are shown <br />fo-.:- existing conditIons. <br /> <br />ACKNOWLEOGEMENTS <br /> <br />LOCATION OF OATA <br /> <br />t'rlneipal tooperatlon and <:oordlnation for Volu.." IU was with <br />representatives of t~e Federal P.rnergency MAnagement Agency (FEMA), the <br />~oio-.:-ado ~ate-':- Conservat10n Board (C~C6), weld County, and tne city of <br />Gre"ley. <br /> <br />Coples of this report are available for public dlstributl0n at the <br />officea listed bclo~. Topographic, hydrologic, aad hydraulic data ased <br />in this scudy are alao on f[le in the Flood Plain.Management Services <br />Branch, Omaha D[strict Corps of Engineers, 215 North 17th Street, <br />Omaha, NE 68102. <br /> <br />Sheet' Draw was intlud~d In the report Flood Insurance Study, Weld <br />County, Colorado, Unincorporated Areas and Town of Eaton, Colorado, <br />Weld County, published by FEMA in December 1979. This study inc.luded <br />Plood Boundary and Ploodway ~~pa (pgYM) and Flood Inaurance Rate Mapa <br />(fiRM), ~ith an eff~ctl~c date of 18 ~~rch i980. <br /> <br />Department of Plannlng Services <br />Weld County Centennial Center. <br />9l510thStreet <br />Greeley, CO 80631 <br /> <br />RELATED STUOIES <br /> <br />County Englneer <br />Weld County <br />P.O. Bo,,758 <br />Greeley, CO 80631 <br /> <br />, <br /> <br />; <br />