FLOOD05886

• Designation Number: 514
• County: Denver
• Community: Denver
• Basin: South Platte
• Title: Flood Insurance Study - Denver, CO, Volume I
• Date: 4/1/1993
• Designation Date: 3/1/2000
• Floodplain - Doc Type: Historic FEMA Regulatory Floodplain Information

Estimates of channel and overbank roughness coefficients were made
after field investigation of the study areas. Manning's "n" values
ranged from 0.015 to 0.040 in the channel and from 0.035 to 0.120
in the overbank areas.

Starting water-surface elevations 'for Harvard Gulch and West
Harvard Gulch were obtained at control sections. The control on
Harvard Gulch was a broadcrested weirflow section over South Logan
Street, and on West Harvard Gulch, a broadcrested weir section over
West South Platte River Drive. Starting water-surface e1eva'tions
for Harvard Gulch Overflow were taken from the Harvard Gulch
profile. For Dry Gulch (Harvard Gulch Tributary), the starting
water-surface elevations were also taken from the Harvard Gulch
profile because these streams are likely to peak at close to the
same time.

Areas of shallow flooding along West Harvard Gulch and Dry Gulch
(Harvard Gulch Tributary) were determined using normal-depth
calculations. Shallow flooding along Harvard Gulch was determined
using normal-depth calculations and a network analysis of
floodf10ws and depths along roads.

Goldsmith Gulch and Southmoor Park Tributarv

Cross section data, Manning's "n" values, and starti'ng water-
surface elevations were developed for use in the 1976 UDFCD Flood
Hazard Area Delineation report for Goldsmith Gulch and its
tributaries (Reference 15). Cross section information was obtained
from topographic maps (Reference 56). Typical Manning's "n" values
for Goldsmith Gulch and Southmoor Park Tributary ranged from 0.030
to 0.045 in the channel, and from 0.035 to 0.055 in the overbank
areas. Starting water-surface elevations for Southmoor Park
Tributary were take-n from the Goldsmith Gulch profiles. Starting
water-surface elevations for Goldsmith Gulch were determined using
a rating curve.

Additional cross sections, added at a berm along Goldsmith Gulch
near the confluence with Cherry Creek, were taken from Cherry Creek
improvement plans (Reference 51). Additional cross section data
from improvement plans were included along Goldsmith Gulch and
Southmoor Park Tributary for the more recent construction of
Eastman Avenue.

Sanderson Gulch

Cross section data on Sanderson Gulch used in the hydraulic
analyses were taken from construction drawings, as-built
construction drawings, field surveys, and topographic mapping
(Reference 57). The starting water-surface elevations were
computed using the West South Platte River Drive crossing as a
control. Roughness coefficients were estimated after field
investigation and ranged from 0.015 to 0.060 in the channel and
from 0.035 to 0.100 in the overbank areas.

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