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United States Department of Agriculture

Agricultural Research Service

Title: Rock Riprap for Grade Control

Authors
item Rice, Charles
item Robinson, Kerry
item Kadavy, Kem

Submitted to: Proceedings ASCE North American Water and Environment Congress
Publication Type: Proceedings
Publication Acceptance Date: June 22, 1996
Publication Date: N/A

Interpretive Summary: Modifications to natural channels generally increase the channel gradient, flow capacity, and flow velocity. The sediment-carrying capacity is increased, and the channels tend to degrade. When degradation occurs, gradient control is required. Gradient control structures are used to locally drop the channel bed level and decrease the channel grade between structures to a stable gradient. One type of grade control structure is a chute formed by stabilizing a steepened portion of the channel by lining the channel with loose riprap. Common procedures used for design of rock riprap channels were evaluated. Based on these evaluations, procedures are recommended for design that should ensure the structural stability and safety of the rock chutes.

Technical Abstract: Gradient control structures are used to locally drop the channel bed level and decrease the channel grade between structures to a stable gradient. One type of grade control structure is a chute formed by stabilizing a steepened portion of the channel by lining the channel with loose riprap. Loose riprap-lined channels or rock chutes can be used in many situations to safely conduct water to a lower elevation and provide effective grade control. The riprap serves to stabilize the chute and dissipate some flow energy. Depending on site conditions and stone availability, rock chutes may offer economic advantages over more traditional type structures. Six procedures for the design of riprap-lined channels were evaluated. Based on these evaluations, procedures are recommended for design that should ensure the structural stability and safety of the rock chutes. Results from two three-dimensional field-scale rock chute tests provide verification of the procedures recommended for design.

Last Modified: 10/23/2014
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