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<br />d. Total-area weighted effective slope factor (precipitation <br />increase due to effective upslope~ SF = 1.057. <br /> <br />For the June 1921 storm transposition shown on plate 12, the relocation <br />adjustment factor (TF) was determined by substituting the above data <br />in the following formula: <br /> <br />= Wpa ~ SF <br />TF X "...- X _ <br />Wpa ~'c SF <br /> <br />TF = 1.473 X <br />1.399 <br /> <br />\I( 13 ._~l X <br />>/(14. U) <br /> <br />1. 037 <br />1. 057 <br /> <br />TF = 1.053 X 0.98 X 0.98 = 1.01 <br /> <br />The adjustment factor (TF) for the 1921 storm under similar meteorologi- <br />cal conditions as occurred, without maximization, would be 1.03 for <br />geographic relocation (Wg and T). With the added effect of orographic <br />upslope (SF = 0.98) the ombine~ adjustment would be just under one per- <br />cent. This is well within the degree of accuracy inherent to storm <br />transpositions. Therefore, the June 1921 storm as it occurred, without <br />adjustment, was transposed to the critical location to determine the <br />standard project flood for the Arkansas River at Las Animas. <br /> <br />5-06. Standard projeet fl.ood.- The transposed June 1921 storm <br />resulted in an average rainfall of 4.11 inches over the contributing <br />drainage area between Pueblo damsite and Las Animas. The average rain- <br />fall over each of the 9 subareas was computed and the rainfall excess <br />for each area was determined by use of the rainfall-runoff curves shown <br />on plate 10. The rainfall excess was applied to the appropriate unit <br />hydro graph and the resulting flood hydrographs were routed by the <br />Successive-Average-Lag Method, and combined to determine the standard <br />project flood hydrograph at Las Animas. The routing times for sub- <br />areas are listed below. <br /> <br />Subarea Subarea <br />No. Desij!TIation Travel Times (Hours) <br />1 Fountain Creek 24.0 <br />2 St. Charles River 22.1 <br />3 Huerfano River 20.1 <br />4 Chico Creek 21.2 <br />5 Apishapa River 14.9 <br />6 Timpas Creek 0 <br />7 Kramer Creek 7.2 <br />8 Horse Creek 2.2 <br />9 Adobe Creek 0 <br /> 19 <br /> <br />