Laserfiche WebLink
<br />Peak discharge-drainage area relationships for all streams studi€'r1 <br />in detail are shown in Table 1. <br /> <br />Tributalies 1 and 2 were studied by dppruximdce mei hod;:; U;:;illq <br />the Rational Method. <br /> <br />J.< Hydraulic Analyses <br /> <br />Analyses of the hydraulic characteristics of the. t !c'(hli_nq r:nlllC('S <br />studied in the county were carried out to p.t.ovitk (....-:~ imai ,'~; <br />of the elevations of floods of the selected recurr{~nc{~ :ll\LI~rV---1J ~': <br />along each of these flooding sources. <br /> <br />For detailed studied streams, the water-surface (?l{~val:inn:; l)f: <br />floods of the selected reCUrrence intervals were (;1 lrnpllt','li t- h'-''---~lJq1J <br />use of the U.s. Army Corps of Engineers HEC-2 SLpp--b,wi...\o,I,lh'l Cl)JllFltcr <br />program (Reference 7). The results obtained trnlil j h{~ tiEl' -.: UlllltY.JtJ" <br />program were adjusted on the profiles to within toi l~J. ,1lll't-'~' 1,1 <br />the vicinity of bridges to more accurately repreB~'nl ,1\'1 U.ll 11~),-',ill~(; <br />conditions (Reference 8). <br /> <br />Cross sections used in the backwater analyses for Yalllpa F 1.V(~J' . <br />the lower portion of Fortification Creek, Bl:othertl)l1 GU.'-.dl, and <br />the portion of Cedar Mountain Gulch upstream of \I.~;. llHl!W,'l' ';0 <br />were obtained from the Colorado Water Conservation Hc.rrd In l'er'~L t-:-; <br />prepared by the U. S. Army Corps of Engineers (Refel <';)CE"C :1 and <br />4). Cross sections used ~n the backwater analyses 1"01 t.hE' \IPPCL <br />portion of Fortification Creek, Sand Gulch, Sand Gulch Tributary, <br />Lay Creek, and Big Gulch were obtained by aer ia1 pllot.og ,,,..,"letlY <br />(Reference 9). Cross sections for the lower portion of l~~'ddr <br />Mountain Gulch and all of Pine Ridge Gulch were fj eld Fuivey,',L <br />The below-water sections of all cross sections well' obt .lir'l.t..'0 hy <br />field measurement. All bridges, dams, and cuJvcru' Wt..'lC j iL~}d- <br />sur veyed to obtain elevati.on data and structUl dl 9~'L'n:\'{ l~'. <br /> <br />Locations of selected crOSS sections used in toile hydi JU.L1C drL1'i~'~~',':- <br />are shown on the Flood Profiles (Exhibit 1). FOl ,;tll'im l'E'smCl".,' <br />for which a floodway is computed (Section. 4.2), sl2-1......ct.€d ....lO!:;S <br />section locations are also shown on the Flood Boundaj y ,jl1<.: ~-'~t'<-':(~\'-,:: <br />Map (Exhibit 2). <br /> <br />Roughness factors (Manning's "nil) used in the hydr,.n::il' CCC1~~Ut.-:::.~-l~~:'<-:' <br />for the study streams were chosen by engineering ) ";9r(.c'1": ,,;oj <br />based on field observations of the flooding sOuI....~es ai-,D tIc,',] <br />plain areas. Roughness values for the main channel ot alj S',~:"C2T:~~ <br />studied ranged from 0.030 to 0.050; flood plain roughness values <br />ranged from 0.035 to 0.080. <br /> <br />12 <br />