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<br />Freque~cy-discha~ge relatior.5~i?s :or ~ry Creek Basin a~d <br />Spring G~lc~ we~e computed ~si~g ~~e U.S. A~~y Corps of <br />E~gir.eers 3EC-l Flood Hyd~oqra?~ ?ac~age (Refere~ce 10). <br /> <br />Sy~thetic f~ao~ hycroqra9hs c8=p~tec ~y t~is ~e~~oc re- <br />flect the effects of ?rec~pi~a~icn c~aracteristic of ~he <br />basi~, grc~~a cover, slope, drainage a~ea, and ct~er phy- <br />sical charac~e~istics c= t~e cra~nase basi~. ~nere <br />availa~:e, hycroloqic da~a were co~pared ~it~ other stud- <br />ies co~pleted i~ the a~ea (Refe~e~ces ~l a~d 12~. The <br />effects or dete~tio~ storage ~ear State Eig~way 66 anc <br />at ~ongs ?eak Jac on S?~in~ G~lc~ were st~cied (Reference <br />11) arrc fo~~d to ~e insig~ifica~t for ~he ~ag~i~~ce of <br />~~e floods co~sidered i~ ~~is study. T~at portion of the <br />Sp~ing G~lch Eas~~ located ~or~h and eas~ o~ Te~ry ~a~e <br />is co~s~cered ~o be co~tai~ed co=plete:y ~y ~erry La~e. <br /> <br />~~e cajor portion 0: ~~e Dry Creek Basi~ ~s locatec O~~- <br />sice ~he li~its a~ ~~e s~~dy area. Ru~of= fro~ t~~5 a~ea <br />cc~~r~but~~s to ?ea~ cisc~arges ~ithi~ t~e S~~GY reac~ <br />is li~ited ~y the Cc~orado and Sout~er~ Rail~cad, ~hic~ <br />civerts mcs~ of t~e ~9strea~ r~~of! no~t~ ~o the S~. Vrai~ <br />River. <br /> <br />Rainfall da~a for t~e sy~~~etic hydrclog~c analysis ~as <br />ta~e~ fro~ the Rainfall/R~~of~ I~for~a~ic~ Report ~Re~- <br />erence 13). T~e disc~arges cOL~uted usi~S t~e 3EC-l p~o- <br />g~a~ we~e veri=ied using t~e P~ains Region eq~a~io~s ce- <br />vel oped by the G.S. Geological Survey (~e=ere~ce l4). <br />Peak discharges were also veri~ied by t~e Soi~ Ccnserva- <br />tio~ Service r~~c=f prediction ~e~~od (~e=ere~ce IS} . <br /> <br />Discharses fo~ the SOO-year floacs of all s~rea~s ~e~e <br />checked by s~~aig~t l~~e ex~~apola~ion 0= =~eq~e~cies <br />prevlo~s~y ceter~ined ~sins t~e ?~oced~re c= t~e L.S. <br />Geoloqical S~rvey (Refe~e~ces 5 a~Q 6), a~~ co~pared to <br />the C.S. Arny Cor?s cf ~ng~~ee~s S~anca=G Pro~ec~ Pleoe <br />data w~en ava~lable. <br /> <br />3.2 3vdraulic Analvses <br /> <br />A~a~yses of the ~ydraulic charac~eris~ics or st~ea=s l~ <br />t~e co~~~~i~y were carriec out ~o p~cvice esti~ates c~ <br />elevatio~s 0= =100ds o~ the selected rec~rre~ce i~~e~- <br />vals along eac~ s~reac st~died in detail. <br /> <br />Water-surface elevatio~s 0= floods 0= ~he selected re- <br />c~rre~ce i~te~vals were cocp~tec t~ro~g~ t~e ~se 0= the <br />D.S. Arrr.y Carps cf ~~gineers, HEC-2 water-s~r=ace pro- <br />files cocnuter nrocra~ (Refe~er.ce 16). Star~i~o wa~er- <br />s~rface eievatic~s-for Left Ear.d Cree~, ~ry Cree~, a~G <br />Spring Gulch correspond to the computed watE~-s~rface <br /> <br />16 <br />