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Colorado Plateau K~ <br />The ~~nly Colorado Plateau data that is available for a watershed in Colorado has a K~ of <br />0.06~~. The range of K~ for all Colorado Plateau, Great Basin and Southwest Desert <br />watersheds from Figure 4-8 (Cudworth, 1989) is from 0.042 to 0.070. FOR WESTERN <br />RANi~ELAND WATERSHEDS OF COLORADO, A K~ OF 0.05 t0 0.07 IS A REASONABLE RANGE <br />FOR THE 100-YEAR FLOOD, 0.04 to 0.06 FOR THE THUNDERSTORM PMF AND 0.05 to 0.07 <br />FOR THE GENERAL STORM PMF. <br />It is noted that the value of K~ should be selected based on site specific data, or regional <br />data, or an evaluation of K~, data for a similar watershed, but lacking such data, the <br />recoirmended K~ values should provide reasonable results. <br />K~~r Aaricultural Watersheds: No lag data exists for watersheds that are entirely <br />agric,ultural. Data exists for three watersheds near Lamar, Colorado, that have extensive <br />agric,ultural area associated with them. Those watersheds have drainage areas from 40 to <br />more; than 200 square miles and the K~ values for those three watersheds are all about <br />0.04, Previous research by the author (Sabol, 1993) indicates that the K~ value for small, <br />hom~~geneous agricultural fields are in the range 0.06 to 0.09. A smaller value of K„ is <br />expected for larger drainage areas where a significant portion of the flow path, L, is a <br />defir.ed watercourse. Recommended values of K~ for agricultural watersheds or subbasins <br />are s~hown in Table 5. <br />Table 5 <br />Rec~mmended Values of K„ for Agricul~ural Drainage Basins <br />A Large, nonhomogeneous area consisting <br /> of discrete agricultural fields connected by Kn = 0.04 <br /> a defined watercourse network <br />B Relatively large, homogeneous <br /> agricultural field(s) with a poorly defined K~ = 0.06 <br /> drainage network <br />C Small, homogeneous agricultural field K~ - 0.09 <br />19 March 2007 20 <br />