Laserfiche WebLink
2.04.7(2) <br />I relationships estimated from a regional frequency analysis of <br />i gaging stations in the Gunnison River Basin. Records used in this <br />' analysis covered at least 10 years of unregulated flow. <br />' A regulated peak flow frequency curve for present conditions <br />at the Somerset index point was developed from analysis of flows <br />' recorded after construction of Paonia Dam, and from reservoir <br />routing studies previously made by the Corps of Engineers and the <br />L4ater and Power Resources Service. Regulated peak flow curves <br />for the downstream index points were developed hy: <br />1. computing the difference from the curves developed <br />' for natural (unregulated) and present (regulated.) <br />conditions at Somerset, and <br />' 2. subtracting that difference from the curves developed <br />for natural conditions at the four downstream index <br />points. <br />Peak flows (for the 10-,50-,100-, and 500-year floods, existing <br />stream regimen) resulting from the foregoing hydrologic analysis <br />are shown on Table 2.04.7(2)(b)(i)-3. <br />1 <br />Peak flow values for 10-,50-, 100, and 500- year floods (together <br />' with corresponding water surface elevations) at each cross section <br />used in the hydraulic analysis made for this report are shown on <br />' Table 2.04.7(2)(b)(i)-4. <br />' Profiles of the 10-, 50-, 100-, and 500-year floods near Somerset <br />are shown on Drawing 2.04.7(2)(b)(i)-2. Flood elevations were <br />computed through use of the Corps of Engineers step-backwater <br />program HEC-2. Basic cross section input was from field survey <br />data furnished by the Colorado ;dater Conservation Board and <br />' Delta and Gunnison Counties. nepth of water in the channel <br />and adjacent flooded areas can be determined from the profiles. <br />' Velocity of flow during a 100-year flood on the P]orth Fork <br />Gunnison River would average about 7-10 feet per second in the <br />REVISED Ptay 15, 1981 47-2d <br />