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|Investigation of proposed dike systems on the Mississippi River. Report 2, New Madrid Bar Reach : hydraulic model investigation
|United States. Mississippi River Commission.
United States. Army. Corps of Engineers. Lower Mississippi Valley Division.
Pokrefke, Thomas J.
Franco, John J.
New Madrid Bar Reach
|Hydraulics Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
|Miscellaneous paper (U.S. Army Engineer Waterways Experiment Station) ; H-70-1 rept.2.
Abstract: This investigation is one phase of a general model study to determine the effectiveness of dike systems proposed for improvement of troublesome reaches on the Mississippi River. This report describes and gives results of tests concerned with the development of plans for the improvement of the New Madrid reach of the river, which is located about 890 river miles above Head of Passes. A movable-bed model reproducing approximately 11 miles of the Mississippi River to a horizontal scale of 1:480 and a vertical scale of 1:60 was used to develop plans that would improve and stabilize the navigation channel through the reach and eliminate or reduce the need for maintenance dredging. The channel in the vicinity of New Madrid, Missouri, has been especially troublesome because of the divided flow and poor channel alignment. Flow near New Madrid is divided by a large island and further divided by a large sandbar between the channel along the left side of the island and the channel along the left bank. The navigation channel at the time of initiation of this study was along the left side of the island and then turned sharply toward the left bank before crossing back toward the right bank downstream of the island. Maintenance of the channel along the right side of the island was required as an access to the port facilities at the city of New Madrid. The plans tested included the construction of four dikes along the left riverbank and the dredging of a pilot cut along the lower portion of New Madrid bar and modifications to the alignment or number of dikes. Results of this investigation indicated the following: (A.) Developments in the reach were affected to some extent by division of flow around New Madrid bar, flow across the bar during high stages, erosion-resistant material in the riverbed, and tendency for the channel to meander within its banks. (B.) Under most conditions, an adequate channel could be developed in the reach with the originally proposed plan. Some maintenance dredging might be required near the head of New Madrid bar, depending on the flow condition and movement of sand waves through the reach. (C.) Conditions near the head of New Madrid bar could be improved with a chevron-type dike at the head of the bar, but would require an additional spur dike along the left bank upstream of the four original plan dikes. (D.) None of the plans tested had any appreciable effect on conditions within the channel to the right of New Madrid bar. (E.) Stabilization of the left side of New Madrid bar would be required to maintain a satisfactory alignment of the navigation channel along that side of the bar.
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