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

I

I

I

2.3

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

the analysis.
from the upper
resultnnt peak
flow pr€,sented.

If this was indeed the case, the extra runoff
basin would have significantly increased the
discharge and may explain the lligher value of

Hydrologic Analysis

Due to the large differences between the peak discharges and
concern expressed by the City of Colorado Springs over the
validity of the FIS findings, a complete new hydrologic
analysis was performed for this watershed. The Shooks Run
Basin was divided into two primary subbasins referred to as the
IIUpper" and "Lower" basi.ns in Figure 2.1. These subbasins were
further divided Into smaller numbered basins for input into the
TR-20 model. With the exception of subbasin 3, the ten lower
subbasins are all south of Constitution Avenue.

Detailecl analysis of the diversion structure and flow capacity
of Van Buren Ditch provided stage-discharge curves that were
incorporated into the hydrologic modeling. The storage
capacity table and stage-discharge curve for the Patty Jewett
Pond were also included in order to simulate the routing
characteristics of this structure. The rainfall depth
presented in Tahle 1.1 for the "general" case was used for the
24-hour storm in this watershed. The values generated for
area, CN and Tc are presented in Table 2.2.
TABl.E U .::. !'UMMARY OF SHR BASIN PARAMETERS

DRAINAGE AREA CURVE NUMBER TIME OF
SUBBASIN m!lare mi les1 CN CONCENTRATION . Ie
lu 0.23 78 0.41
2u 1. 75 69 1. 64
1 0.37 73 0.96
2 0.68 68 0.73
3 1. 83 72 0.84
4 1. 36 80 0.90
5 0.54 78 0.45
6 0.47 85 0.52
7 1. 59 81 0.72
8 0.37 75 0.76
9 0.16 88 0.31
10 0.45 83 0.34

Peak discharges for the 24-hour AMC II storm are presented in
Tab le 2.3. The location of each hydro graph discharge point is
shown in Figure 2.1. It was found that the diversion structure
at Constitution Avenue does serve to effectively divert the
upper basin flow to Monument Creek. A negligible amount of
discharge to the Shooks Run Channel may occur during the 500-
year event but it would not influence the peak discharge
downstream in the main channel. With this in mind, the
cumulative area listed in Table 2.3 only includes the subbasins
of the Lower Shooks Run Basin.

12

R€~OURC€ CON~UlTI\NT~ INC