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<br />TECHNICAL MANUAL
<br />
<br />Example 5,nNoY'thern PLateau Region
<br />
<br />Flood information is required dt North Sand Wash secondary road crossing
<br />(Jat 40044'34", long 108026'13", NW!;NW" sec. 17, T. 9 N" R. 98 W,).
<br />
<br />Map coverage: Lone Mountain quadrangle, scale = 1 :62,500
<br />Craig quadrangle, scale = 1 :250,000,
<br />
<br />Parameters
<br />
<br />Q =discharge, in cubic feet per second,
<br />A ~drainage area, in square miles,
<br />P =mean annual precipitation, in inches,
<br />o =depth, in feet, and
<br />55=streambed slope, in feet per mile.
<br />
<br />A =70.4 mi2.
<br />P =12 inches (From U.5, Weather Bureau (1967) isohyetal map. Use grid
<br />method to obtain P at 20 points in basin and average.)
<br />
<br />Contour downstream from point=6,080 ft
<br />Contour upstream from point=6,120 ft
<br />Distance between contours=2,O mi
<br />55=(6,120-6,080)~2.0=20 ft/mi
<br />
<br />QlO =11 ,OAo.552pO.706=11.0(70.4)0.552(12)0.706=11.0(10,5)(5.78)= 668 ft3/s
<br />Q50 =70.5AO.509pO.289=70,5(70,4)0.509(12)0.289=70,5(8.72)(2,05)=1,260 ft3/s
<br />Ql 00=135AO.494PO .143=135 00. 4) 0.494 (12) 0.1" 3=135 (8.18) (1,113)=1,580 ft 3/5
<br />Q500=293AO.469=293(70,4)0.469=293(7,35)=1,980 ft3/s
<br />
<br />010 =13.955-0.288=13,9(20)-0.288=13,9(0,42)=5.9 ft
<br />050 =16.655-0.311=16,6(20)-0.311=16,6(0,39)=6.5 ft
<br />0100=17.255-0.310=17.2(20)-0.3]0=17,2(0,40)=6.9 ft
<br />0500=19,055-0.321=19,0(20)-0.321=19,0(0.38)=7.2 ft
<br />
<br />If desired, use a graphical solution for Ql00 and 0100:
<br />Ql00--Refer to figure 7,
<br />
<br />For A=70.4 mi2 and P=12 inches,
<br />
<br />From figure 7, Qloo=I,580 ft3/s,
<br />
<br />OlOO--Refer to figure 8,
<br />For 55=20 ft.
<br />From figure 8, 0100=6,9 ft.
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