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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6.3

Hydrologic Analysis

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The hydrologic parameters developed by the LDTL study were
found to be reasonable and formed the basIs for this analysis.
As needed, subbasins, curve numbers, routing coefficients and
Tc's were modified to reflect existing conditions. Additional
adjustments were made to incorporate the current storm criteria
as outlined by the DCM.

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The rainfall depth presented in Table 1.1 for the "general"
case was used for the 24-hour storm in this watershed. The
values representing Area, CN, Tc are presented in Table 6.2.

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TABLE 6.2 -=- SUMMARY OF TG BASIN PARAMETERS
DRAINAGE AREA CURVE NUMBER TIME OF
SUBBASIN ( square miles) CN CONCENTRATION. Ic
1 0.369 83 0.42
2 0.200 85 0.37
3 0.227 85 0.31
4 0.141, 85 0.17
5 0.059 87 0.12
6 0.078 86 0.11
7 0.153 81 0.30
8 0.117 80 0.29
9 0.117 83 0.16
10 0.184 78 0.30
11 0.250 81 0.25
12 0.113 83 0.24
13 0.169 78 0.28
14 0.239 85 0.43
15 0.070 85 0.26

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Peak discharges for the 24-hour AMC II storms are presented in
Table 6.3 The location of each hydro graph discharge point is
shown in Figure 6.1

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TABLE !!....l SUMMARY OF TG DISCHARGES BY RQl
DRAINAGE AREA PEAK DISCHARGE(l)(cfs)
LOCATION .!~\lare mUill 10 YR 50 YR 100 YR 500 YR
TG 1 1.15 1,440 2,070 2,470 3,200
TC 2 1. 30 1,610 2,320 2,780 3,700
TG 3 1. 53 1,800 2,640 3,160 4,200
TG 4 1.72 1,970 2,910 3,490 4,700
TG 5 1. 89 2,11,0 3,160 3,800 5,150
TG 6 2.14 2,440 3,610 4,340 5,850
TG 7 2.49 2,820 4,180 5,01,0 6,800
(1) These VEl lues result from the 24-hour AMC II storm.

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