FLOOD01954

• Designation Number: 420
• County: El Paso
• Community: Colorado Springs
• Title: FIS - Colorado Springs, CO, Volume I of III
• Date: 8/16/1995
• Designation Date: 3/1/1996
• Floodplain - Doc Type: Floodplain Report/Masterplan

basin's hydrology. The hydrologiQ analyses contained in the drainage
basin studies accurately estimated the lOa-year peak discharges. The
assumption of fully developed conditions in each basin was acceptable
for use in this study. since ~he drainage reports contained only
lOa-year peak discharges, flow rates for the 10-, SO-, and SOO-year
recurrence intervals were estimated in accordance with References 12
and 13. The discharge-frequenc~ relationship for Spring Creek was
prepared by the study contra~tor, using the SGS methods in
conjunction with the Colorado Springs storm runoff criteria manual
(Reference 13). Peak disCharges per unit area far Spring Creek
showed a good comparison to the' other urban basins studied herein.
Soil information was obtained fr.om 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 lS), and Colorado Springs Municioal Airport. Runwav
17L-3SR. Grading and Drainage Pl~n (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 Drv Creek Master Drairiage Studv (Reference 2). Analyses of
peak flow rates for the 10-' and SO-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
elevations 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-suJ."face elevations for the 10-, SO-,
100-, and SOO-year recurrence intervals.

Hydraulic analyses were not ca~ried out to provide water-surface
elevations for the 10- and SOryear recurrence intervals for Dr)
Creek, North Channel Dry Creek, i North Fork Dry Creek, South Valle)
Dry Creek, and Big Valley.

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

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