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<br />Table 1
<br />Sub-watersheds of Frenchmen Creek
<br />
<br />Sub- Drainage Area Length (L) Lea (mi) Average Slope
<br />watershed (sq mi) Miles Feet ft/mi ft/ft
<br />A 24.4 21.5 113,520 11.0 14,784 0.0028
<br />B 15.6 12.4 65,472 6.6 20.592 0.0039
<br />C 3,3 4.5 23,760 2.4 27.984 0.0053
<br />D 4.0 3.8 20,064 2.8 12.144 0,0023
<br />E 6.9 5.4 28,512 3.8 12,144 0,0023
<br />F 7,8 9.6 50,668 5.2 20.592 0,0039
<br />G 17.5 15.5 81,840 8.0 19.008 0.0036
<br />H 15.3 16.5 87,120 8.2 14.784 0.0028
<br />I 37.8 16,2 85,536 9.8 14.784 0,0028
<br />J 0.4 1.4 7,392 0,85 12.672 0,0024
<br />K 22.4 13,2 69,696 8.3 14.256 0.0027
<br />L 5.4 7.2 38,016 3,9 12.672 0,0024
<br />M 18.4 14,3 75,504 7,5 18.480 0.0035
<br />N 3.9 3,2 16,896 2,3 23.760 0.0045
<br />0 13.5 14.2 74,976 7.3 19.008 0.0036
<br />P 30.7 , 16.1 85,008 9,7 14.784 0,0028
<br />Q 6.4 4,3 22,704 2.6 7.920 0.0015
<br />R 12,5 9,0 47,520 5.6 15.312 0.0029
<br />S 1.3 1.9 10,032 0.8 7,920 0.0015
<br />
<br />Source: USACE (calculation and data sheets)
<br />Lea = distance from the centroid of the sub-watershed to its outlet (miles).
<br />
<br />A perusal of the USGS topographic maps (7,5-minute Quadrangles) suggests that the sub-
<br />watershed distribution is reasonably realistic. Generally, division of a watershed into large
<br />number of sub-watersheds with several relatively small sub-basins tends to result in higher peak
<br />flows for the entire watershed unless adequate lags are included in combining hydro graphs from
<br />different sub-watersheds (Prakash, 1986).
<br />
<br />The Frenchman Creek watershed is located in Logan, Phillips, and Sedgwick counties in
<br />Colorado. In this region, the climate is semi-arid with mean annual precipitation of 19 inches in
<br />the eastern part of Logan County and 17,63 inches at Holoyoke (USDA, 1976; Gale Research
<br />Company, 1985), This region of northeastern Colorado has a crop growing season of about 140
<br />days, which is suitable for the major crops of wheat, spring grains, com, alfalfa, and sugar beets.
<br />Land use within the watershed is primarily agriculture including irrigated and dry cropland,
<br />range land, and pastures, The land use and climate in the watershed are similar to those in
<br />southwestern Nebraska and northwestern Kansas.
<br />
<br />Draft Letter Report
<br />Independent Review of Hydrologic Analysis for Frenchman Creek
<br />Contract No. DACW 4 I -00-D-0026-000 1
<br />
<br />Flood Plain Management Services Special Study
<br />Holyoke. Colorado
<br />June 18,2001
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