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United States Department of Agriculture

Agricultural Research Service

Title: Low-Drop Grade-Control Structure

Authors
item Rice, Charles
item Kadavy, Kem

Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 15, 1998
Publication Date: N/A

Interpretive Summary: Grade-control structures prevent channel degradation and stabilize degrading channels. Experiments were conducted to develop design criteria for a low-drop, grade-control structure that has good performance characteristics and general acceptance by the engineering community involved with stabilization of degrading channels. Criteria are presented to design the structure given the channel width, critical depth, drop height, and tailwater elevation, and to determine the size and placement of riprap downstream of the structure to ensure the integrity of the structure.

Technical Abstract: Grade-control structures are necessary to prevent channel degradation and to stabilize a degrading channel. An acceptable structure for low-drop conditions (drop height/critical depth, h/dc </= 1.0) is not currently available for some locations, especially in urban areas. Two- and three- dimensional physical model studies were conducted to develop design criteria for a low-drop grade-control structure that has good performance characteristics and general acceptance by the engineering community involved with stabilization of degrading channels. The developed structure has rounded entrance abutments, a 2:1 sloping floor at the entrance, 0.5dc high floor blocks with 2:1 upstream sloping face, and a 0.25dc high end sill with a 3:1 upstream sloping face. Criteria are presented to design the structure and stable downstream riprap given the channel width, critical depth, drop height, and tailwater elevation. A minimum tailwater elevation is required for acceptable performance of the structure.

Last Modified: 4/21/2014
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