FLOOD01644

• Designation Number: 46
• County: Denver
• Community: Denver
• Title: Flood Hazard Boundary Map - Supplementary Report, Sanderson Gulch & Weir Gulch, Denver, Colorado
• Date: 3/1/1975
• Designation Date: 7/1/1975
• Floodplain - Doc Type: Floodplain Report/Masterplan

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these figures with those reconunended in the r.1anual, it was
determined that the following coefficients could be used
throughout the total study area.

Infiltration
Pervious Storage
Impervious Storage
Loss

0.75 in/hr
0.50 in
0.30 in
5%

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The degree of development, of course, varied for each subdivision.

DESIGN POINTS

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There were a total of 44 design points or sub-basins designated
for this project. The breakdown in each gulch was: Main
Sanderson Gulch, 14; South Sanderson (south of Jewell and west
of Garrison), two; North Sanderson Gulch, six; Main Weir Gulch,
18; North Weir Gulch, two; and South Weir Gulch, two. The design
points were set at road crossings, reservoirs, and points of
channel confluence. Also, design sub-basins were sized to about
200 acres with some exceptions, particularly off-channel basins.
The relative location of the design points are shown in the
overall basin maps, Sheet No. 2 and 3 in Volume No.2.

For each point, the peak storm runoff rate was computed for
conditions of existing and total development, as required in
the contract. A summary of the flows is provided on the
Discharge Probability Profiles for ea~h gulch as discussed
in the following section.

SUMMARY OF HYDROLOGICAL DATA

A summary of all the input and output hydrological information
which was used in the study of the Sanderson and Weir Gulches
has been submitted to the Drainage District for their records.
In summary, the information includes the description of the
physical features of each sub-basin including the area, length,
length to centroid and slope; the assumed degree and type of
development including the degree of perviousness and imper-
viousness; the coefficients used for each type of development
assumed within the sub-basin and all other hydrological para-
meters used in the analysis.

A summary of the hydrological study is provided in this report
in the form of Discharge Probability Profiles and selected
actual storm hydrographs at particular design points. The
discharge profiles for the existing and developed conditions
of Phase A and the final hydrology of Phase B are presented in
Figure 111-4 through Figure 111-13 as follows:

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