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<br />Table 8
<br />Estimated peak Flows of Frenchman Creek at Holoyoke
<br />
<br />Method Model Parameters Estimated Peak Flows (cfs)
<br /> 25-year 100-year
<br />HEC-1/HMS Model (i)USBR Lag time 6,808 13,314
<br /> (ii)CN = 60 and 64
<br /> (iii)24-hr storm
<br />HEC-1/HMS Model (i) Lag time by Stream 6,260 12,145
<br /> Hydraulics Method with V
<br /> = 2 ft/sec,
<br /> (ii)CN = 60 and 64
<br /> (iii)24-hr storm
<br />HEC-1/HMS Model (i) Lag time by Stream 6,288 12,250
<br /> Hydraulics Method with V
<br /> = 2 ft/sec,
<br /> (ii)CN = 60 and 64
<br /> (iii)48-hr storm
<br />HEC-1/HMS Model (i) Lag time by Stream 6,312 11,587
<br /> Hydraulics Method with V
<br /> \, = 1 ft/sec,
<br /> (ii)CN = 64 and 68
<br /> (iii)48-hr storm
<br />Previous Study Lognormal extrapolation 4,913 8,940
<br />(USACE, 1980) and drainage area ratio
<br />Indirect Peak. Flow High water marks and 3,600-4000 N.A.
<br />Estimates Manning's equation
<br />Regression Equation D,A. N,A. 11,417
<br />for Republican River (7,307-15,527)
<br />basin
<br />Regression Equations D,A., h, s, and Sp 5,930 12,471
<br />for watersheds in (7,981-16,961)
<br />Kansas (4,210-7,650)
<br />Regression Equations D,A., s, and h4,50 3,379 6,491
<br />for Region 2, (540-6,217) (1,039-11,943)
<br />Nebraska
<br />Regression Equation D,A. and s N.A, 28,257
<br />for Plains region of (21,475-37,299)
<br />Eastern Colorado
<br />
<br />*
<br />
<br />N,A. indicates 'not applicable'.
<br />
<br />Draft Letter Report
<br />Independent Review of Hydrologic Analysis for Frenchman Creek
<br />Contract No, DACW41-00-D-0026-000 I
<br />
<br />Flood Plain Management Services Special Study
<br />Holyoke, Colorado
<br />June 18,2001
<br />
<br />Page 13
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