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<br />- .'- .'..,," .- .".-'~""~'-'-- <br /> <br />,_J..""t:i, <br /> <br />Yampa River basin to account for the high,~r density of vegetation in these <br />areas. This is consistent with the approach used fo;, the Stea.niboat Springs <br />FPI study. Lower initial losses were used fo:r computation of the June SPF <br />as compared to the August SPF since it is believed that wetter ground <br />condit:lons would exist in June. <br /> <br />d. Flood routings - Flood routings between various points. .,n the <br />Yampa River were accomplished using the Tatum routing procedure. Tatum <br />steps "ere established so that travel tim,~s for the SPF were e.quivalent <br />to those observed during the April 1974 flood. Flows were not routed <br />between the various index points on Forti:Eication Cr,~ek and the other <br />small streams around Craig. These routings ..:ill be accomplished by the <br />Flood Plain Management Section. <br /> <br />e. SPF-Yampa River - Computations of th.~ general rain SPY f"r the <br />Yampa River were made for both the June and August sltorms using the <br />storm amounts, unit hydrographs, loss ratl~s, .'tnd routing crite.rta <br />discussed previously. The effects of the small reservoirs in the <br />basin (see paragraph 2) were neglected since they control rela.tively <br />small areas and do not have any dedicated flood control space. <br />Computation of the June SPF was made assuming that all areas bel"w the <br />June snowline (8500' elev) were contributing. Snowmelt was acco'unted <br />for by using a baseflow equal to the June snOl-'Illelt experienced during <br />high runoff years. Computation of the August SPF was made assuming <br />that the entire basin was contributing and that baselElow was equal to <br />normal August flows. Resulting standard project floods at sev'e'c.al <br />points on the Yampa River are tabulated belm'. Also shown, fo'r <br />comparison, are flows developed for the same points :In other stl.dies. <br /> <br /> Peak FlO1~(cfs) <br /> DA ..June Aug <br />Location (sq.. mi:~_i'.l' F SPF <br />Yampa River at Steamboat . Springs 604 8200 13800 <br />Yampa River at Hayden 1430 25000 28000 <br />Yampa River. at Craig 2131 29000 28000 <br /> <br />Pk. Flows <br />fr"m other <br />s tl~dies <br />(cf~ <br /> <br />14500(1) <br /> <br />24900(2) <br /> <br />(1) Spy from Steamboat Springs FPI study <br />(2) 500 yr. flood from USBR Flood Insurance Study at Hayden. <br /> <br />The June SPF at Craig was adopted for this study. <br /> <br />f. Cloudburst rainfloods - Cloudburst floods on Fortificati"n <br />Creek and the other small streams around Cra.:lg were computed u.sing the <br />storm amounts, unit hydro graphs and loss irates discussed previously. <br /> <br />9 <br /> <br />'!'I~lf"'~~!f:~ <br />. .., <br />