FLOOD10515

• County: Gunnison
• Community: Marble and Vicinity
• Stream Name: Crystal River
• Basin: Gunnison
• Title: Floodplain Information Report Crystal River - Technical Appendix
• Date: 5/1/2004
• Prepared For: Marble and CWCB
• Prepared By: ICON Engineering, Inc.
• Floodplain - Doc Type: Floodplain Report/Masterplan

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1.1

Hydrologic Analyses

Hydrologic analyses were carried out to establish the peak discharge-frequency
relationships for each flooding source studied in detail affecting the geographic
area of the Town of Marble, Colorado.

Discharges along the Crystal River were calculated using the PEAKFQ computer
program (Reference 1) which uses a log-Pearson Type III frequency analysis.
The analysis is based on USGS gage information, totaling over 45 years of
record, along the Crystal River, just downstream of the Town of Marble. Peak
discharges from the USGS gaging stations were adjusted along the study reach
based on the guidelines provided in the Manual for Estimating Characteristics Of
Natural-Flow Streams in Colorado. Technical Manual No.1 (Reference 2).

Peak discharge-drainage area relationships for the streams studied by detailed
methods are shown in Table 1.

Table 1. Summary of Discharges

Flooding Source and Location

Drainage Area Peak Discharge (cfs)
(Square Miles) to-Year 50-Year lOO-Year 500-Year

Crystal River
Confluence with Rapid Creek
Confluence with Milton Creek
Town of Marble
Upstream Limit of Study

93.05
83.65
73.59
53.32

1994
1833
1657
1284

2445
2248
2031
1575

2625
2413
2181
1691

3028
2783
2515
1950

9.0

BffiLIOGRAPHY AND REFERENCES

I. U.S. Geological Survey, Computer Program PEAKFO Version 4.0. Annual Flood
Frequency Analysis Using Bulletin 17B Guidelines. December 2000.

2. Colorado Water Conservation Board, Colorado Department of Natural Resources,
Manual for Estimating Flood Characteristics of Natural-Flow Streams in Colorado.
Technical Manual No.1, 1976