FLOOD10395 (2) - Laserfiche WebLink

Home Browse Search

e e relationship for the individual precipitation stations in southwest Colorado. The annual I-day and 2-day precipitation amounts for the period of record were used to develop station statistics for seven precipitation stations in the region. The 1 % amounts were computed as well as relationship of 2-day: I-day ratio of 1 % precipitation amounts for each station. The precipitation stations, 1 % amounts for 1- and 2-day durations, and station ratios for 2-day: I-day are listed on Table 12. An adopted regional ratio of 1.32 for 2-day to I-day relationship was used to obtain the 1 % 2-day point rainfall over the upper Dolores watershed. The adopted regional ratio is the average of the ratios computed for the seven stations shown below in Table 12. Table 12 Regional Analysis for I-day vs. 2-day 1 % Storm Precipitation Depths for Stations in or near Upper Dolores River Basin Station Elevation 2-Day I-day Ratio Name (feet) (inch) (inch) % Telluride 8672 4.41 3.09 142.7 Silverton 9278 4.04 3.19 126.6 Durango 6600 4.15 3.12 133.0 Cortez 6153 2.80 1.85 151.4 Dolores 6940 2.86 2.13 134.3 Rico 8800 3.71 2.94 126.2 Mancos 6990 2.49 2.27 109.7 Adopted Regional Ratio = 1.32 7.3 Storm Centerings. Two 1 % general rainstorm centerings were developed for the upper Dolores River basin, one centered over the West Dolores River ("West Fork"), the other over the upper mainstem Dolores River ("East Fork"). The West Fork centering used a specific 1 % storm centered over the West Dolores River near Stoner (West Fork Dolores), with concurrent centerings (in descending order) on the upper mainstem Dolores River below Rico (Dolores Headwaters), Dolores Upper Mid, Bear Creek, Dolores Mid, Dolores Lower, and Lost Canyon Creek. The East Fork centering used a specific 1 % storm centered over the upper mainstem e.. Dolores River below Rico (Dolores Headwaters), with concurrent centerings (in descending 25