FLOOD10410

• Designation Number: 418
• County: El Paso
• Community: Colorado Springs
• Basin: Arkansas
• Title: FIS - Colorado Springs - Vol 1
• Date: 9/30/1992
• Prepared By: FEMA
• Floodplain - Doc Type: Historic FEMA Regulatory Floodplain Information

in this study. Since the drainage reports contained only 100-year
peak discharges, flow rates for the 10-, 50-, and SOO-year recur-
rence intervals were estimated in accordance with References 12
and 13. The discharge-frequency relationship for Spring Creek was
prepared by the study contractor, using the SCS methods in con-
junction with the Colorado Springs storm runoff criteria manual
(Reference 13). Peak discharges per unit area for Spring Creek
showed a good comparison to the other urban basins studied herein.
Soil information was obtained from an SCS survey of El Paso County
(Reference 14).

Peak flow rates were developed by the study contractor for the
Peterson Field Drainage using Peterson Field Master Drainage Report
(Reference 15), and Colorado Springs Municipal Airport, Runway
17L-3SR, Grading and Drainage Plan (Reference 16). Peak flows
from the master drainage report were reevaluated by routing flows
through the detention basins recommended in Reference 13.

Peak discharges for Dry Creek, North Channel Dry Creek, North Fork
Dry Creek, South Valley Dry Creek, and Big Valley were obtained
from the report Dry Creek Master Drainage Study (Reference 2).
Analyses of peak flow rates for the 10- and 50-year frequencies
were not available.

Peak discharge-drainage area relationships for streams studied in
Colorado Springs are shown in Table 1.

3.2 Hydraulic Analyses

Analyses of the hydraulic characteristics of flooding from the
sources studied were carried out to provide estimates of the eleva-
tions of floods of the selected recurrence intervals.

Water-surface elevations were developed with the COE HEC-2 water-
surface profile computer program (Reference 17). Flood profiles
were drawn showing computed water-surface elevations for the 10-,
50-, 100-, and SOO-year recurrence intervals.

Hydraulic analyses were not carried out to provide water-surface
elevations for the 10- and 50-year recurrence intervals for Dry
Creek, North Channel Dry Creek, North Fork Dry Creek, South Valley
Dry Creek, and Big Valley.

~

.
Cross sections for backwater analyses of the streams studied in
detail were obtained from aerial topographic maps compiled between
1972 and 1983 (References 18, 19, 20, 21, and 22). Cross sections
for Fbuntain and Monument Creeks were compiled by Hogan and Olhausen,
Inc. (Reference 18). Cross sections for Camp Creek, Cheyenne
Creek, Bear Creek, and South Shooks Run were compiled from aerial
topographic photography (References 19 and 20).

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