FLOOD08334

• County: Mesa
• Community: Grand Junction
• Stream Name: Colorado River
• Basin: Colorado Mainstem
• Title: Colorado River Flood Analysis
• Date: 1/1/1984
• Prepared For: Mesa County
• Prepared By: Greenhorne & O'Mara, Inc.
• Floodplain - Doc Type: Floodplain Report/Masterplan

TABLE 3

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Estimated number

DAMAGE REVIEW.

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of units flooded
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for various storm frequencies *

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Flooded Area 2-Year 5-Year 10-Year 50-Year 100- Y-ear 500-Year
---
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A )>1 JJ' -0- -0- -0- 120 151 163
r.
B Q (,.,,I_V -0- -0- -0- 98 110 125
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C {o"( ",V" -0- -0- -0- 12 14 62
D ( -0- -0- -0- 50 70 72
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* The number of un its were est i mated from aerial photographs and orthophoto mapp i ng
of the study reach.

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As the table indicates, a large number of proper.ties would be in the floodplain
for the larger, less frequent flood events. The infrequency of flooding would,
however, implythat~U'age annual d~~j).!LP_9_t~Dtij!J is relatively small.
However, fh"e--damages that could be incurred durin<) large floods is very
substantial and danger ~o human life would be high where levee syste~s are
overtopped and fail and W1en overbank depths exceed 2 feet. \\

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IMPROVEMENT PLAN \
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Existing Conditions

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A field reconnaissance ~as completed throughout the study reach in order to
identify and evaluate pe^manent and temporary 'levees. The areas where major
levee systems were identified are described as follows:

1) There is both a permanent and temporary levee system along th~_ nor:..!!!..2.ank of
the Colorado River just uQ1i.t.r.ea.JJLQf the Grand Avenue Bridge adjacent to the
"Riverside" area. The permanent levee consists of rock filled gabion
" -"- -~-->-_.~.._---------._---.---'--
baskets which provice a vertical sloped bank along the river. The levee
"extenas-from the Granj Avenue Bridge abutment east approximately ~()OO feet.
fIt the present time, there are remains of a temporc,ry levee'which was
constructed on top 0" the existing gabion \,all. This levee was built to

6