FLOOD09874

• County: Statewide
• Community: State of Colorado
• Basin: Statewide
• Title: Use of Riprap for Bank Protection
• Date: 6/1/1967
• Prepared By: USDOT
• Floodplain - Doc Type: Project

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ADAPTED FROM HYDRAULIC CHART 712- III
HYDRAULIC DESIGN CRITERIA, CORPS OF .'
ENGINEERS /
k .. 50~ stone size I
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0.8

0.2

00

0.2

0.4

0.6

0.8

1.0

Velocity Against Stone - F.P.S... Vs
Average Vel-oeity In Cb.aonel ~ l.PoB. V

'v # .:.'1
/.

c.

FIG. 1 . VELOCITY AGAIlfST STOllE Olf CHANNEL BOTTOM

The siloe of stone required to resist displacement from direct impinge-
ment of the current as might occur with a sharp change in streu alinement
is sreater than the value obtained from figure 2, although research data is
lacking on Just how much larger the stone should be. The California Divi
sion of Highways (6) recamlllends doublill8 the velocity against the stone as
determined tor strii:1ght alinement before entering figure 2 for stone size.
Lane (2) recOIIIIIIends reducing the allowable vel.ocity by 22 percent for very
sinuous channels; for determining stone size by figure 2, the velocity (Vs)
would be increased by 22 percent. Until data are available for determining
the stOne size at the point of impingement, a factor which would vary from
1 to 2 depending upon the severity at the attack by the current, should be
applied to the velocity Vs betore entering figure 2.

11-5

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