Semi-dykes (bottom rapids) as devices  controlling sediment transfer and regional ecology

by

A.E. Shchodro1, S.A. Sholar1,2

 1Institute of Natural and Technical Systems, RF, Sevastopol, Lenin St., 28

 E-mail: ashodro@ya.ru

2Sevastopol State University, RF, Sevastopol, Universitetskaya St., 33

 E-mail: sa.sholar@mail.ru

DOI: 10.33075/2220-5861-2023-3-123-132 

UDC 626: 532.5:556.537                                                                                                                                  

Abstract:

The paper considers some types of semi-dykes (boons, bottom rapids) – river hydraulic structures designed to organize the flow of water torrents entering sea estuaries or floodplains, improve the ecological state of water areas and combat local erosion as negative manifestations of the water element: reducing erosion, controlling sediment deposits, maximizing washing of the entire water area, and especially the coastal zone, saturating the flow with oxygen, facilitating the collection of floating debris, etc.

The fundamental design issues are the determination of the main parameters of the structure: its relative height and length, the angle of location relative to the oncoming flow vector, and the size of the stones that protect the bottom from local erosion near the head of the structures. To address these issues, laboratory hydraulic studies of low flooded semi-dyke (LFD) were undertaken over a fairly wide range of changes in the initial parameters of these structures. The methodology for determining the first three parameters is described in a number of publications. With regard to the size of the stone that protects the bottom of the structure from erosion, empirical dependencies are obtained that make it possible to determine both the value of the maximum specific flow rates at the head of the structure and the maximum actual, bottom velocities of the turbulent flow of 1% security, on the basis of which it is possible to reasonably assign the indicated diameter.

Keywords: semi-dams, hydraulic structures, sediment transfer.

To quote: 

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