FLOOD05377

• County: Arapahoe
• Community: Littleton
• Stream Name: South Platte River
• Basin: South Platte
• Title: Floodplain and Floodway Delineation for the ABM Riverfront Property
• Date: 3/1/1980
• Prepared For: Littleton
• Prepared By: WRC Engineering, Inc.
• Floodplain - Doc Type: Floodplain Report/Masterplan

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A.

Floodplain Delineation - The water surface profiles in the FIS ~.
the study reach are based on a minimum number of cross section~/~;-

for

The FIS hydraulic analysis is based. on one cruss section approximately
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~ne hall-mile downstream from Belleview and one at the downstreaa
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side of the Be11eview bridge. The analysis herein included eleven
cross sections ~t approximately 300 feet intervals. The floodplain
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delineations are in close agreement. bowevp~ th_ flood elevations
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differ somewhat. It appears that the 100-year profile bas been ~?
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incorrectly plotted in the FIS when compared to tne ~r flood i t

frequency profiles (Plate 29P\ ~;;-~tUl)-,~"-~:- Sl::') d~+-Y ?

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The FIS also shows that water will overtop Be11eview Avenue

east V'"
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of the bridge. Our analysis indicates that an existing levy on the ~~

east bank upstream from Be11eview prevents water froa flowing into ~~~~\~
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this area and therefore all of the flood water will flow under tbe ~-

bridge. However, the flood elevations downstream frOm the bridge
indicate that a backwater condition may be created which will force
water back across Be11eview into the low area in the east overbank.

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This condition would be prevented by filling of the subject property~
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B. F100dway Limits - The f100dway boundary shown in the FIS was drawn
based on the two cross sections described in the previous section.
The boundaries were plotted at each cross section and smooth lines
were drawn between the cross sections. Thus the f100dway boundary
through the subject property was drawn based primarily on engineering
judgment to represent streamlined limits characteristic of flOOdways.,&~~
1'1"\"
The floodway boundary determined in this study was computed using
the same computer modeling techniques as the FIS. However, the ex-
tensive number of cross sections used provides for a more accurate
and detailed delineation.

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