Please use this identifier to cite or link to this item:
Title: Old River Existing Low-Sill Control Structure, Louisiana : hydraulic model investigation
Authors: United States. Army. Corps of Engineers. New Orleans District.
Rothwell, Edward D.
Grace, John L.
Keywords: Control structures
Hydraulic models
Old River Control Structure
Mississippi River
Open channel flow
Flow conditions
Stilling basin performance
Hydraulic gates
Flood control
Hydraulic structures
Publisher: Hydraulics Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: Technical report (U.S. Army Engineer Waterways Experiment Station) ; H-77-2.
Description: Technical Report
Abstract: The Old River Existing Low-Sill Control Structure consists of eleven 44-ft-wide gate bays, Nos. 1-11 from right to left looking downstream, separated by piers. The three center bays (low gate bays) have a crest elevation of - 5.0 ft; and the eight outer bays (high gate bays), four bays on each side of the center section, have a crest elevation of +10.0 ft. The stilling basin consists of a horizontal apron, divided into three sections, that is surmounted with two rows of staggered 10-ft-high baffles spaced 12 ft apart and terminated with a 3-ft-high vertical end sill. The center section, located downstream of the low gate bays, is 150 ft wide and has an apron elevation of -12.0 ft. The two outer sections, downstream of the high gate bays, are 221 ft wide and have an apron elevation of -5.0 ft. Model investigations were conducted using two 1:36-scale section models and a 1:150-scale section model to evaluate and develop a satisfactory means of regulating the existing structure to achieve the desired flow objectives without creating adverse hydraulic flow conditions. The model was also used to study the stilling basin performance and flow characteristics for uncontrolled- and controlled-flow operations, measure the dynamic loads induced in the cables and supporting devices during placement of the vertical-lift gates, pressures along the structure (weir crest to stilling basin apron) and velocities in the approach, stilling basin, and exit channel and to determine by observation the relative degree of turbulence in the stilling basin and exit channel. Model tests indicated that partial closure of the gate bays from the top of the structure (orifice flow under the gates) would be the most effective method of regulating the structure and maintaining satisfactory stilling basin performance and is therefore the recommended plan of regulating the existing structure. The Froude number of flow in the exit channel should not exceed 0.5 for any gate opening downstream of the low bays and 0.4 for gate openings below 11.25 ft and 0.5 for gate openings greater than 11.25 ft downstream of the high bays. Pressures obtained for a range of flow conditions indicated no serious negative pressures should be encountered on boundaries of the prototype structure subject to flow. The model also indicated that with one gate bay fully closed and adjacent bays open severe turbulence was induced upstream of the fully closed gate. Therefore, the method of regulating the structure by means of fully closing various gate bays should be discontinued for headwaters in excess of 37.0 ft msl.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Technical Report

Files in This Item:
File Description SizeFormat 
TR-HL-77-2.pdf11.33 MBAdobe PDFThumbnail