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<br />principal method used. Gaging stations within Hydrologic Area No. 10 of <br />Flood-Frequency Region B (listed below) were used to establish the regional <br />rela tionship. <br /> <br />.... <br /> <br />GAGING STATIONS IN FLOOD <br />FREQUENCY REGION B HYDROLOGIC AREA NO. 10 <br /> <br />~ <br /> <br />USGS Drainage Length <br />Station Area of Record <br />No. Station Location (sq. mi.) (years) Period of Record <br />091450 Uncompahgre River at Ouray 44.0 14 1911-1924 <br />091460 Uncompahgre River below Ouray 76.0 16 1914-1929 <br />091464 West Fork Dallas Creek near <br /> Ridgeway 13.2 15 1956-1970 <br />091465 East Fork Dallas Creek near <br /> Ridgeway 16.8 16 1948-1970 <br />091650 Dolores River below Rico 105.0 25 1952-1976 <br />091681 Disappointment Creek near Dove <br /> Creek 145.0 19 1958-1976 <br />091720 Fall Creek near Fall Creek 33.5 18 1942-1959 <br />091725 San Miguel River near Placerville 308.0 40 1930-1976 <br />091745 Cottonwood Creek near Nucla 43.0 10 1942-1951 <br />091750 Naturita Creek near Norwood 27.7 12 1942-1952 <br />091755 San Miguel River at Naturita 1080.0 48 1918-1976 <br />091775 Taylor Creek near Gateway 12.0 23 1945-1967 <br /> <br />..,...... <br /> <br />, . <br />~ <br /> <br />The method developed by the U.S. Water Resources Council (Reference 4) <br />was used to determine the flood flow frequency relationship based on log- <br />Pearson Type III distribution analysis for each selected gaging station. <br />Gaging stations used for developing the regional relationship were selected <br />according to the criteria of (1) stations which have 10 or more years of <br />record and (2) stations where peak flows are not affected by regulation and <br />diversion. <br /> <br />... <br /> <br />Since the annual peak discharge published in the USGS Water Supply Papers <br />(References 5, 6, and 7) and the USGS Surface Water Records (Reference 8) <br />were a mixture of flood flows caused by snowmelt and rainfall events, the <br />regional relationship establi~hed by using these annual peak discharges does <br />not reflect intense rainfall produced floods. A more detailed method was <br />used for each gaging station to develop regional relationships for'this area. <br />The procedures are described as follows: (1) separating the rain and <br />snowmelt data at each gaging station, develOping statistics for each type of <br />event, and statistically combining the two frequency curves (stream flow <br />records were obtained from the USGS Denver Federal Center); (2) adjusting <br />short pedod statistics to reflect long period. values if they are closely <br /> <br />.. <br /> <br />--; <br /> <br />s <br /> <br />7 <br />