FLOOD02337

• County: Statewide
• Community: State
• Stream Name: South Platte River
• Basin: South Platte
• Title: Geomorphic Assessment at Surveyed Cross-sections South Platte River
• Date: 6/1/1996
• Prepared For: UDFCD
• Prepared By: Michael Stevens
• Floodplain - Doc Type: Floodplain Report/Masterplan

Cross Section 2

Station 102+60 South of Highway 7

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Cross Section 1

Station 58+80 South of Highway 7

East Bank: Recently constructed bike path and park on cleaned up, restored, and flattened
banlc Bank is stable with riprap at the base, grass and other vegetation above.
Some of the new plantings and construction were damaged by the sustained
flows during thespring of 1995. Remedial work has been completed.

West Bank: Stable from 1986 to 1994, erosion of 12 ft since. Bank is gravel with 1.5 ft of
sand on top. There are sparse weeds on the slope. Downstream on CDOT right-
of -way, the bank is covered with concrete rubble which serves as the approach
embankment to the bridge.

River Bed: Stable sand and gravel bed, some Urban Veneer. Upstream, high gravel point
bar on the west side, bank erosion upstream from the bar and bend. Immediately
downstream are a side bar on the east bank and State Highway 7 bridge with five
piers. On the upstream side of the center pier, there is a large, high deposit of
woody debris and bed material, vegetated with willows since 1994 (Spot Photo
1). The reach is straight.

A long-time resident and canoeist offered that the river is much improved since
the 1960's when raw sewage used to float by Brighton.

There is a grade-control structure about 0.6 miles downstream from this section,
keeping it from degrading.

East Bank: Stable bank is grassed sand and gravel in the lee of a hardpoint and east
abutment oflarge boulder grade-control structure with boat chute. Downstream
from this section, bare gravel bank had been eroding before the construction of
the structure. Floodplain is covered in part by an old cottonwood grove.

West Bank: Stable to present. May change due to realigned flow through the boat chute.
Bank is gravel, with grass. Floodplain is prairie. Downstream, the outside of the
bend has been cleaned of large concrete pipe sections, revegetated, and the
bottom portion of the bank riprapped and is now stable.

River Bed: Undergoing change, the flow is deep due to local scour from flow through the
boat chute. The bed is not visible due to turbidity. The products of the local
scour have been deposit in a middle gravel bar just downstream. Upstream, there
is a large and high sand and gravel point bar with a few clumps of juvenile
willows. Deep part of channel was not surveyed in 1996. The cross section is
between bends.

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