FLOOD07240

• Designation Number: 316
• County: San Miguel
• Community: Unincorporated San Miguel County
• Basin: Gunnison
• Title: FIS - San Miguel County, Colorado, and Incorporated Areas: Sawpit and Telluride
• Date: 9/1/1988
• Designation Date: 3/1/1991
• Floodplain - Doc Type: Floodplain Report/Masterplan

TABLE 2. SUMMARY OF DISCHARGES (cont'd)

Flooding Source
and Location

San Miguel River
(cont'd)
At confluence of
Mill Creek
At Telluride western
corporate limit
At confluence of
Cornet Creek
At Telluride eastern
corporate limit

Leopard Creek

Fall Creek

Cornet Creek
At confluence with
San Miguel River

*Mudf10w Discharge

Drainage Area
(square miles)

Peak Discharges (cubic feet per second)
10-Year 50-Year 100-Year 500-Year

27.68 580 1,040 1,360 2,460
26.48 560 1,010 1,320 2,420
25.25 540 980 1,280 2,330
15.63 380 710 940 1,770
62.4 1,0$0 1,810 2,300 3,930
42.0 7'80 1,390 1,780 3,130

2.38

210

415

590
1,500*

1,300

3.2 Hydraulic Analyses

Analyses of the hydraulic characteristics of flooding from the
sources studied were carried out to provide estimates of the
elevations of floods of the se1~cted recurrence intervals.

Cross section data for streams in the area were obtained from
aerial photographs (Reference 12); the below-water sections were
obtained by field measurement; All bridges and culverts were
measured to obtain elevation data and structural geometry.

Locations of selected cross sections used in the hydraulic analyses
are shown on the Flood Profiles (Exhibit 1). For stream segments
for which a floodway was comp~ted (Section 4.2), selected cross
section locations are also sho-fn on the Flood Insurance Rate Map
(Exhibit 2). .

Roughness coefficients (Manning's "n") were estimated by field
inspection at each cross section and checked for reasonableness
against a recognized standard text (Reference 13). Roughness
values for the main channel range from 0.025 to 0.060; the overbank
values range from 0.025 to 0.10~

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