FLOOD10043

• County: Larimer
• Community: Fort Collins
• Stream Name: Fossil Creek
• Basin: South Platte
• Title: Documentation for Selection of Manning's Roughness Coefficient for Fossil Creek Master Drainageway Planning Study
• Date: 12/1/1981
• Prepared For: Larimer County
• Prepared By: Simons Li & Associates Inc.
• Floodplain - Doc Type: Floodplain Report/Masterplan

I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I

A field reconnaissance of Fossil Creek, Stanton Creek, Lang Gulch, Smith

Creek and Burns Tributary was conducted during November, 1981, to obtain

hydrologic and hydraulic data in accordance with the Fossil Creek Master

Drainageway planning Study by Simons, Li & Associates, Inc. (SLA) for the City

of Fort Collins in cooperation with the Colorado Water Conservation Board and

Larimer County. The collection of photographs presented in this book document

the selection of Manning's roughness coefficient, n I along the channels and

overhanks of Fossil Creek and tributary drainages.

Figure 1 shows the drainage basins with the location of channel crossings

for Fossil Creek and the 4 tributaries. Table 1 shows the criteria often used

for the selection of Manningls roughness coefficient, and the source of the

information. Most roughness coefficients were based on previous estimates by

the U.S. Army Corps of Engineers. Figures 2 through 41 show the hydraulic

characteristics of the drainages. Channel sections upstream and downstream of

each crossing are shown with the selected n value for the left overbank

(LOB), right overbank (ROB) and channel. (Left and right are corresponding to

the viewer's and photographer's left and right.) Table 2 is a summary of the

selected roughness coefficients.