FLOOD07429

• Designation Number: 60
• County: Morgan
• Community: Brush
• Stream Name: Beaver Creek
• Basin: South Platte
• Title: Floodplain Information Report - Beaver Creek, Brush, Colorado
• Date: 4/1/1976
• Prepared For: Brush
• Prepared By: Gingery Associates, Inc.
• Floodplain - Doc Type: Floodplain Report/Masterplan

An ~erial view of the City during the 1935 flood is shown in
Figure 1.
Another ~ccount of the 1935 flood is given in The Brush News
Tribune article entitled, "FLOOD!", reprinted in this report as
Figure 2.
In 1965, when flood waters again c~me down Beaver Creek
threatening the City of Brush, the community was more prepared.
The City constructed a five-foot high dike around the southeast
portion of town to protect that area against the onrushing fload
waters. The dike held as the flood waters came within inches of
overtopping the dike and again threatening the downtown area of
Brush. Regardless, the business district had taken action to
minimize flood damages. The merchants had not only sand bagged
their places of business, but also ~ad removed stock merchandise
from their basements to higher and ,lafer elevations.
Fload waters took the Highway 6-34 bridge out of service in
1965. Other bridges in the area were also washed out and closed
for a period of two to three days until repairs could be completed.
The U. S. Geological S~rvcy estimatGd the peak discharge of
the 1965 flood at State Highway 71 crossing south of Brush to be
24,.100 cfs. This flood waS compar<>.blc to approxi!llately a 25-yeilr
floed event. Figure 3 shows an aerial view of the approximat~
flood limits of the 1965 flood In the arca southeast of Brush.

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HYDROLOGIC AND HYOR1I.ULIC DETER"lINATIONS

Pleod Characteristics

Floor. events on Beaver Creek are the result of intense thunder-

~t0r~s occurring i~ the ~~~in. Bc~~g ~ubjcct to heavy rain 0v~nt~

of cloudburst intensity, flooding in the upper part of the basin
will ch~racteristical1y have high peak discharges of short duration
lasting only a few hours. As the flood event passes into the lower
reaches of the creek nei"lr Brush, channel storage reduce" the flood

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magnitude and the flood stages.
The flood peaks used in this study are characteristic of rain-
fall-generated f10ad events with long flood durations. The esti-
mated peak flood flows computed are listed in Table 1.

TABLE 1
Flood Discharqes
Beaver Creek at Brush

Flood Frequency
10-Year
50-Year
100-Year
SOO-Year

Flood Discharqe

12,400 cfs
37,000 cfs
55,000 cfs
119,600 cfs

The 100-year flood is one with a pe<>.k flow magnitude that has
a 1 percent chance of being equalled or exceeded in any given year
and a frequency of occurrence of about once in 100 years on the
long-term average. Similarly, the 10-year, 50-year and SOO-year
floods have a 10 percent, 2 percent and 0.2 percent chance of
heing equalled or exceeded in any given year, and an average fre-
quency of occurrence of about once in the number of years indicated.
These flow~ have been estimated based On recorded flood oc-
t:urrcnces in t,'\e high plains area of e~stern Colorado, western
Kansas and southwestern NebraSka, and are typical of the Beaver
Creek drainage area.
Typically, the flood events will move into the Brush community
at a speed of 2 to 4. miles per hour. Flood peaks may last for a
duration of 2 to 10 hours while high flood stages may remain in
the area for p",riods of 20 to 30 hours.
The flat ~op~graphy ~hara~~~ri~ti~ nf this rPil.ch of Bpaver
Creek tends to widen the flood plain arca and reduce the depths
and velocities of the flood flow as it passes through the area.
In the reach of Beaver Creek between the Burlington Northern rail-
road and Interstate 76, the average flow velocity in the ~ain

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