FLOOD03173

• County: Statewide
• Community: All
• Basin: Statewide
• Title: State of Colorado 2002 Flood Documentation Report
• Date: 1/1/2003
• Prepared For: CWCB
• Prepared By: ICON Engineering, Inc.
• Floodplain - Doc Type: Flood Documentation Report

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Figure 2.8 - State of Colorado NEXRAD
Radar Image July 19"', 2002 at 8:00PM.

Figure 2.9 - Map of the Town of Rifle In Relation
to the State of Colorado.
Map courtesy of the Mapquest webslte.

Hvdrolol!ic and Hvdraulic Conclusions

Only a small amount of information could be found about the hydrologic characteristics
of Rifle and Government Creeks. According to information obtained from the city's
chamber of commerce website and Mapquest, both Rifle and Government creeks flow
north to south into the town of Rifle. After entering the town, Government creek joins
Rifle creek and Rifle creek continues south through the city where, after receiving more
flows from various sources, it flows directly into the Co lorado River.

Hydrologic analyses were performed using available baseline data from NOAA Atlas 2 in
order to generate Intensity Duration Frequency, or IDF, curves for rainfall events within
the town of Rifle. Using the amount of rainfall reported for the July 18th storm event (1.5
inches of rain in 30 minutes), and the derived total precipitation amounts for the city, one
could estimate the frequency of the specific event. However, since this storm event
occurred northwest of the city, one must take into account the total area impacted by the
storm upstream of the studied city (see Figure 2.10 on the next page).

Figure 2.10 shows the estimated area boundary for the studies events. The storms were
centered over the Roan Plateau area and the resulting precipitation flowed off the plateau
spilling into Rifle Creek, Government Creek, and it's western tributaries.

CON Engineering, Inc

12

January 2003