FLOOD07884

• County: El Paso
• Community: Colorado Springs
• Stream Name: Sand Creek - Center Fork
• Basin: South Platte
• Title: Flood Hazard Analyses
• Date: 6/3/1974
• Prepared For: Colorado Springs, El Paso County
• Prepared By: USDA Soil Conservation Service
• Floodplain - Doc Type: Floodplain Report/Masterplan

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COMPUTATIONS
The Colorado Urban Hydrograph Procedure (CUHP) was used to determine
peak runoff from the 50 and 100 year storms. Coefficients in this
procedure were developed specifically for eastern Colorado environ-
mental conditions. Coefficients are presented in the Urban Storm
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.Drainage Criteria Manual prepared for the Denver Regional Council

of Governments.

The basin was assumed to be 40% impervious. An infiltration rate of

one-half inch per hour was used. The 50 year design storm produced

2.14 inches of rainfall in one hour, The 100 year design storm

produced 2.35 inches in one hour. The peak for the 100 year storm

was taken from storm hydrographs presented in the PPACG study entitled
Comprehensive Drainage Plan for the Pikes Peak Region. The peak dis-

charges for the 50 year storm were calculated by the firm of George

L. Williams, Consulting Engineer. Empirical a~ Statistical c~-

parisons were made to extrapolate the Standard Project Flood. This

was necessary due to the complete lack of stream gage data and dis-

charge records for this basin. Two excellent sources of data are

available for this purpose. One is a record of peak discharges known

to date for basins in the Front Range region. The second is the
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Standard Project Flood calculations made for Monument Creek by the

US Army Corps of Engineers.

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The US Army Corps of Engineers estimates the peak discharge from the

Standard Project Flood in Monument Creek to be 63,400 c.f.s. or a

discharge of 270 c.f.s. per square mile.

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