The aim of the research is to survey, analyze and assess the work of existing fish protecting construction (FPC) of the type “flat net screen with fish diverting” at the Don main canal, and to develop recommendations for design optimizing of the given construction. A number of disadvantages of the given construction were revealed during the analysis and assessment of its work. The key disadvantage is the high level of injures of juvenile fish at the net screen and during the fish diverting. In addition, such a construction is quite complex and requires considerable energy inputs for operation. Insufficient operating efficiency of FPC due to uneven flushing of net screens, which results in the decreasing of throughput capacity of FPC and fish injuries, was established as well. The failure of inspection sensors of flushing equipment and therefore the decreasing of operating efficiency of FPC was marked. Imperfection of constructions, primarily for fish-receiving elements, and poor quality of building were revealed. The survey of FPC results in the conclusion that the given construction has reached the end of its service life and requires reconstruction and extension. Indicated disadvantages are the reasons of low efficiency of the whole fish protecting unit which affects on survivability of juvenile fish. The study results in developing recommendations for design optimizing of the given construction including the proposal on the use of more advanced designs of net chambers and patterns of net, recommendations for net cleaning by water-air jets, proposals for increasing the sizes of fish-receiving ports (0.7×6.0 m), inlets of bottom tunnel (0.7×1.0 m), and bottom tunnels (0.9×1.3 m), which allow maintenance (technical survey, debris and sediment removal) and repair, and will create safety speed regime for fish diverting.
Keywords: fish protecting structure, net screen, reliability, juvenile fish, fish diverting, flushing equipment.
