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<br />HYDROLOGIC ANALYSES <br /> <br />The hydrologic analyses used in this study were based on the <br />hydrologic analyses developed by the U.S. Corps of Engineers <br />Sacramento District (COE) for the 1977 Craig, Colorado Flood Hazard <br />Information Report (Reference 1). A copy of the COE Flood Hazard <br />Information Hydrology Report (FHI) is included in the Appendix of <br />this report. The following paragraphs give a detailed explanation <br />of the hydrologic analyses. The results are listed in the Results <br />Section of this report. <br /> <br />Brotherton, <br /> <br />P~,~e__J~ i dg e_iln d_~~cl--"~I' <br /> <br />,~ <br />, .~u <br />.0.\ <br />,S",) <br />}!ounta~.I1:~:~VI1 <br />J... /1 <br /> <br />\\" <br /> <br />Yampa Ri ver <br />Gulches <br /> <br />and <br /> <br />Peak discharges for these streams were computed by the COE and <br />were obtained directly from the 1977 Craig FHI report. <br /> <br />Sand Gulch and Sand Gulch Tr:J blJt~.r:1 <br /> <br />Peak discharges for tbese streams were ccmputed by <br />constructing a Drainage Area - Peak Discharge relationship for <br />flooding sources in the Craig area with relatively the same <br />size drainage areas. The streams used to construct the curve <br />were Pine Ridge, Cedar Mountain and Brotherton Gulches. The <br />computations are included in the Appendix of this report. <br /> <br />Fortification Creek <br /> <br />A. <br /> <br />Mouth to Western Boundary of Section 30 <br /> <br />Peak discharges for <br />and were obtained <br />report. <br /> <br />this reach were computed by the <br />directly from the 1977 Craig <br /> <br />'1 <br />~\\V <br /> <br />COE <br />FHI <br /> <br />B. Section 30 to Half Section 16 <br /> <br />Peak discharges were calculated by computing cubic feet <br />per second per square mile (CSM) values for Fortification <br />Creek downstream of Section 30 and applying the CSM <br />values to this reach. The calculations are listed in tbe <br />Appendix of this report, <br /> <br />Lay Creek and Big Gulch <br /> <br />Peak discharges for both streams were computed using the <br />procedures outlined in the Craig, Colorado Flood Hazard <br />Information Report. The COE study consists of a detai led <br />probability analysis of stream gage (snow-melt) data in <br />conjunction with the HEC-l rainfall-runoff model (Reference <br />2). For the HEC-l rainfall-runoff model for Lay Creek and Big <br /> <br />- 2- <br />