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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TABLE ~~ =. liUMMARY OF SPR BASIN PARAMETERS
DRAINAGE AREA CURVE NUMBER TIME OF
SUBBASIN .umuare miles}. CN CONCENTRATION . Ie
A 0.50 65 0.322
B 0.69 65 0.424
C 0.16 67 0.348
D 0.25 70 0.500
E 0.20 62 0.332
F 0.28 66 0.582
G 0.24 69 0.457
11-1 0.08 70 0.160
11- 2 0.13 70 0.231
J-l 0.09 79 0.271
J-2 0.14 85 0.332
K 0.15 82 0.470
L-l 0.30 85 0.478
0 0.42 74 0.686

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Rating curves for each of the three culverts were calculated;
these included weir flow for overtopping of roadways. It
should be noted that there is some uncertainty as to the exact
sizing of the Sears Shopping Center culvert. Discharge
estimates were based on informatIon from the ESSW and will be
field-verified before the hydraulic analysis is performed.
Approximate stage/capacity curves were obtaIned at each
location hy planimeter with 1:400 scale mapping at 2-foot
contours.

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A stage-discharge curve for the Big Stratton Reservoir was
available In the ESSW report. Communication wIth the owners of
the reservoIr at the Myron Stratton Home indicated that normal
operating level of the reservoIr Is kept at an elevation well
below the spillway crest. However, as a conservative approach,
it was assumed that the reservoir was full at the beginning of
each storm event.

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The peak discharge results for the 211-hour AMC II storm at the
locations indicated on figure 4.1 are presented in Table 4.3.
The 1,660 cfs value for the 100-year flood at interstate 25 is
approximately 9% hIgher than that established by the ESSW.

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The difference between the two studies is primarily a
consequence of the difference In the two desIgn storms.

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R€~OURC€ CON~ULTI\NT~ INC

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