FLOOD03463

• Designation Number: 72
• County: Adams
• County: Arapahoe
• County: Douglas
• Community: Denver Metro Region
• Stream Name: Van Bibber Creek
• Basin: South Platte
• Title: Major Drainageway Planning - Van Bibber Creek
• Date: 3/1/1977
• Designation Date: 7/1/1977
• Floodplain - Doc Type: Floodplain Report/Masterplan

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-6-

January 6, 1976, on file with the UD&FCD. Included in the
appendix is a summary of the Cp and Ct coefficients, a
summary of basin parameters, land use data and other miscellaneous
hydrologic information. The rainfall information used in the
study was obtained from the Rainfall/Runoff Information Report
(Ref. 5), and is representative of Township 3 South, Ranges
69, 70 and 71 West. A summary of the design rainfall data
and rainfall abstractions used in the analysis is provided
in Table II.

Typical flood hydrographs which were computed and used as a
part of this study are shown in Figures 1, 2, 3, and 4. Discharge-
Probability Profile Charts, showing the 10-year and 100-year
flood peaks for the main stream and south tributary, are
provided in Figures 5 and 6. Table III lists the estimated
peak discharges for the 10-year and 100-vear storm events at
selected reference points.

Table III
Flood Frequency and Discharge**

Table II
Design Rainfall and Abstractions

Impervious area storage
Pervious area storage
Impervious loss
Infiltration

0.10 in.
0.30 in.
0.05 in.
0.50 in./hr.

Location Design Point* 10-Year 100-Year
(cfs) (cfs)
Van Bibber Creek
Confluence 6 1650 3450
Tabor St. (extended) 5 1550 3300
So. Tributary 3 1280 2750
Hogback 1 880 1570
So. Tributary
Confluence 3 780 1400
Ramstetter Reservoir 2
Inflow 290 590
Outflow 260 540
No. Tributary
Confluence 5 425 615
Hyatt Lake 4
Inflow 360 570
Outflow 30 40

Ra~nfall, inches*

Abstractions

2-yr.

10-yr.
1.81

100-yr.
2.57

Arvada, (below Ward Rd.)
Jefferson Co. (above
Ward Rd.)
Jefferson Co. (above
Hogback)

1. 05

1. 03

1.86

2.56

0.80

1. 58

2.19

*storm duration - 2 hrs.

Assumptions made and parameters developed for the hydrologic
computations are based on planned, future basin development.
Future land use planning information for Van Bibber Creek basin
was taken from the Jefferson County Land Us.e Map approved by the
Jefferson County Commissioners on April 2, 1974 and revised on
September 16, 1974. The basis of interpretation of the land
use maps for the purposes of the hydrology study is also provided
in the Hydrology Technical Addendum.

*See Sheet 1, Drainage Basin Boundaries
**Existing Channel Conditions, Future Basin Conditions

Hydraulics, Flood Plain and Floodway Delineation

Hydraulic analyses were completed to determine the water surface
elevations for the 100-year storm event. The elevations Were