FLOOD04641

• County: Denver
• Community: All
• Stream Name: All
• Basin: South Platte
• Title: Proposed Hydrology for use in Hydraulic Analysis of FEMA Flood Studies and Restudies
• Date: 9/1/1989
• Prepared For: State of Colorado
• Prepared By: Resource Consultants
• Floodplain - Doc Type: Educational/Technical/Reference Information

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8.2

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Colorado Springs as shown in Figure 8.1. rt borders three
other basins Included in this study: Sand Creek West Fork on
the west, Sand Creek East Fork Tributary on the East, and Sand
Creek Central Fork on the south. This long slender basin
extends from the Chicago Rock Island and Pacific Railroad 10
ml.les to the north and is approximately 2 miles wide.

Total area of the drainage basin is 15.0 square miles. Slope
averages over a range of 3-4% in the northern area to 6-8% in
the south. the upper portion of the basin is presently
undeveloped. Residential development in the lower basin has
been extensive.

The channel consists primarIly of natural streambed in sandy
material. A small sectIon of the stream in the vicinity of
North Carefree CIrcle has been lIned with soIl cement.

Soils within the basin are a relatively even mix of "A" and "B"
type soils. The only exception is a small area along Powers
Boulevard near North Carefree Circle and extending north: "0"
soils exist there.

Two previous studies of the basin were available for review.
These were the FI.li -=- !;ill of Co lorado Sorin~s (Reference 6) and
Sand Creek Mftster Draina~~ Plannlnp- Study -=- City of Colorado
~g~. s.. E_ll'.asQ. County -=- DevllPoment of Alternate Plans
develop(~d by Simons, Li and Assoc., Ine. (SLA) in cooperation
with Finn & Associates, Ltd. (Reference 17, July 1985).

PrevIous Studies

Hydrology for the frS was based on an SCS flood hazard analysts
report (Reference 18) completed in 1973. According to the FIS,
this study utilized SCS methods to develop peak discharges for
condItions existing at that time. It is doubtful, given the
date of the study, that the effects of a Type IIA rainfall
distribution were included In the analysis.

The hydrologic analysis by SLA was performed in the same manner
as outlined for the West Fork of Sand Creek (see section 7 of
this report). For this watershed, however, the average area
used for subbasins was much smaller.

A summary of peak discharges from the previous studies is
presented in Table 8.1

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