FLOOD02273

• County: Statewide
• Community: State of Colorado
• Stream Name: All
• Basin: Statewide
• Title: Hydraulic Design of Energy Dissipators for Culverts and Channels
• Date: 12/1/1975
• Prepared For: USDOT
• Prepared By: Federal Highway Administration
• Floodplain - Doc Type: Educational/Technical/Reference Information

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flow, the total loss of energy py resistance will be somewhat
greater,with the steeper ,and then flatter slope because
a lesser depth is produced ov~r a greater portion of the
barrel length. This increased loss due to resistance will
be small, however, as will the reduction in outlet velocity.
Formation of a hydraulic jump in the lower barrel is rare,
as the downstream depth required to force a jump will seldom
be encountered. If this type of design is attempted, water
surface profile calculations must be made to insure that
the hydraulic jump relationship is fulfilled.

For culverts on slopes greater than critical, rougher material
will cause greater depth of flow and less velocity in equal
size pipes. Velocity varies inversely with resistance;
therefore, using a corrugated metal pipe instead of a con-
crete pipe will reduce velocity approximately 40 percent,
and substitution of a structural plate c.m. pipe for concrete
will result in about 50 percent reduction in velocity.
Barrel'resistance is obviously an important factor in
reducing velocity at the outlets of culverts on steep
slopes. Chapter VII contains detailed discussion and specific
design information for increasing barrel resistance.

III-I.

Federal Highway Administration, DESIGN CHARTS FOR
OPEN~CHANNEL FLOW, U.S. Government Printing Office,
Washington, D.C., 1961, 105,pp. (Hydraulic Design
Series No.3).

III-2.

Simons, D. B., Stevens, M. A., Watts, F. J., FLOOD
PROTECTION AT CULVERT OUTLETS, Colorado State
University, Fort Collins, Colorado, CER 69-70
DBS-MAS-FJW4, 1970.

III-3.

U.S. Department of the Interior, Bureau of Reclamation,
DESIGN OF SMALL CANAL STRUCTURES, 1974, pp. 127-130.

III-5