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The ~jefinition and measurement of L, L~ and S are the same as previously discussed for the <br />Clark: unit hydrograph. The value of K~, is selected by considering the hydrologic conditions of <br />the vvatershed (or subbasin) of interest to watersheds of similar hydrologic conditions for which <br />Kn v~~lues are available. Calculated values of K~, for various watersheds are presented in the <br />literature by agencies such as the USBR and the U.S. Army Corps of Engineers. <br />The Intent herein is to provide guidance in the selection of K~ values for use in estimating Lag <br />when performing inflow design flood studies for dams in Colorado. <br />Guid,ance is provided for estimating K~ for use in Colorado for the following physiographic types <br />of w~~tersheds: <br />• Rocky Mountain <br />• Colorado Plateau <br />• Great Plains <br />• Agricultural <br />• Urban <br />K~ fcir Rockv Mountain, Great Plains and Colorado Plateau Watersheds: All available <br />Lag, watershed characteristics and K~ data for Colorado watersheds are listed in Tables 3 and 4. <br />Two of the data are for locations in New Mexico but the watersheds lie mostly in Colorado and <br />are therefore included in the data set. Those data are obtained from Sabol (1987). Table 3 <br />lists ~~he data according to increasing watershed size and Table 4 lists the same data according <br />to in~~reasing K~. The 20 watersheds are classified as to type; 13 in the Rocky Mountains (RM), <br />six ir~ the Great Plains (GP) and one in the Colorado Plateau (CP). The storm type is identified <br />for tf~e Rocky Mountain watersheds using information in Table 4-2 and Figure 4-7 of Cudworth <br />(198~9) as to thunderstorm (T) or general storm (G). Five of the Rocky Mountain data are for <br />thun~~erstorms, five are for general storms, and three are of unknown storm type. Measured <br />valuE:s of LL~a/S•o.s versus Lag are plotted in Figure 2 for all 20 data points. <br />19 March 2007 15 <br />