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Anal~isis of the data in Tables 3 and 4 and Figure 2 results in the following <br />recommendations: <br />Rocky Mountain K~, <br />For s,evere thunderstorms, K~ ranges from 0.058 to 0.076. That is consistent with the range <br />of K~ from Figure 4-7 (Cudworth, 1989) where the thunderstorm K~ ranges from 0.050 to <br />0.07,3 for all Rocky Niountain watersheds. FOR THUNDERSTORMS IN ROCKY MOUNTAIN <br />WATERSHEDS OF COLORADO A K~ OF 0.05 t0 0.08 IS A REASONABLE RANGE FOR THE <br />PMF. Selection of K~ depends on flow retarding factors of the watershed and main <br />watercourses. Sparse vegetation, steep slopes, hydraulically "smooth" watercourses and <br />well defined banks with minimal overbank flow all tend to minimize K,,. <br />For qeneral storms, Kn ranges from 0.195 to 0.339. That is consistent with the range of K~ <br />from Figure 4-7 (Cudworth, 1989) where the general storm K~ ranges from 0.130 to 0.260 <br />for all Rocky Mountain watersheds. FOR GENERAL STORMS IN ROCKY MOUNTAII~ <br />WATERSHEDS OF COLORADO, A K~ OF 0.15 t0 0.30 IS A REASONABLE RANGE FO~t THE <br />PMF. Selection of K~ depends on flow retarding factors of the watershed and main <br />watercourses. Sparse vegetation, steep slopes, hydraulically °smooth" watercourses and <br />well ~~efined banks with minimal overbank flow all tend to minimize K,,. <br />More frequent design storms (100-year) are typically assumed to occur as thunderstorm <br />cells within a general storm and those are often modeled as the 24-hour rainfall <br />hypothetical distribution. Under those modeling assumptions 1T IS REASONABLE TO USE <br />THE ROCKY MOUNTAIN THUNDERSTORM DIMENSIONLESS UNIT HYDROGRAPH OR <br />S-GRAPH WITH A KN OF 0.20 TO 0.30 as discussed above for the less intense general storm <br />runoif conditions. <br />Great Plains K~ <br />For C~reat Plains watersheds in Colorado, K~ ranges from 0.030 to 0.041. That is consistent <br />with the range of K~ from Figure 4-6 (Cudworth, 1989) where K~ ranges from 0.030 to 0.069 <br />for a,l Great Plains watersheds. FOR PLAINS AND MOUNTAIN VALLEY WATERSHEDS OF <br />COLURADO, A K~ OF 0.04 to 0.07 IS A REASONABLE RANGE FOR THE 100-YEAR FLOOD, <br />0.03 to 0.06 FOR THE THUNDERSTORM PMF AND 0.04 to 0.07 FOR THE GENERAL STORM <br />PMF. <br />19 March 2007 19 <br />