FLOOD01015

• County: Fremont
• Community: Florence
• Stream Name: Coal Creek, Arkansas River
• Title: Flood Preparedness Plan for the City of Florence Remont County, Colorado
• Date: 6/1/1993
• Prepared For: Florence, Fremont County, CWCB
• Prepared By: US Army Corps of Engineers
• Floodplain - Doc Type: Flood Mitigation/Flood Warning/Watershed Restoration

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2.

2.1 General Descr1Dt::l.on

The Arkansas River basin above Canon City is a high
mountain valley surrounded by mountains reaching altitudes of
more than 14,000 feet. The basin is surrounded on three sides
and part of the fourth by mountain ranges that act as
orographic barriers to major storm systems. The drainage area
at Canon City is 3,117 square miles, and the 100-year flow is
20,500 cubic feet per second (reference 5).

FrOlll Canon City to Florence, the basin opens up into a
wide river valley with fewer orographic barriers. Several
tributaries flow into the Arkansas River, including Four Hile
Creek which has a contributing drainage of 428 square miles.
The 100-year flow at Hinnequa Dam just upstream of Florence on
the Arkansas River is 28,000 cubic feet per second (reference
5). For the Canon City to Florence reach, it is estimated that
the travel time for a flood wave is approximately 2 hours
(reference 7).

At Florence, there are three right bank tributaries that
flow into the Arkansas. These streams are Chandler, Oak, and
Coal Creeks. Table 1 shows these streams with their
corresponding drainage areas and flows (reference 5, 16).

TABLE 1 - ARKAHSAS RIVER TRIBUTARIES AT FLOltEllCE

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These, streams flow northeasterly out of the West Mountain
Range and have a history of flooding in the City of Florence.
Plate 2 shows the entire Arkanaes River watershed above
Florence.

2.2 H1.st:orv of Flood:l.D~

The Arkansas River in Fremont County has a long history
of flooding. Large floods occurred in 1909, 1921, 1933, 1941,
1948, 1949, 1957, and 1965 (Reference 2). Peak flood

2

~ The 100-year flood
has a one percent
chance of occurring
in any given year.

l!i 100-year flow at
Canon City
- 20,500 cfs
- 5353.7 feet NGVD'
- 14.32 feet NWS'

- 10.32 feet

l!i 100-year flow at
Florence
- 28,000 cfs
- 5147.2 feet NGVD
- 9.9 feet

, See Figure 3 for
use of NGVD and 1IWS