The study was conducted at the reclamation water intake facility of Tikhovsky hydroelectric complex. We used data from long-term observations and results of laboratory studies on a 1:20 scale physical model of the Zapan fish protection device. The effectiveness of the model was evaluated using simulators of juvenile fish. Increasing the efficiency of the Zapan fish protection facility is achieved by additional placement in the bottom threshold, which directs the bottom flow along with the young fish to the springboard, where there is an airlift in the form of a bubble curtain that lifts the young along the springboard into the fish-receiving holes of permeable shields. Fish protection design and location in the middle of the water stream do not create a backwater due to low resistance and provide protection for young fish. This increases not only the survival rate of young fish, but also the efficiency of reclamation water intakes. A new design of a fish protection structure for reclamation water intakes of the Zapan type was developed, which provides a fish protection effect of 3 groups of young fish formed by their swimming ability, which allowed determining the size of the elements of the fish protection structure.

The article solves the problem of increasing the level of protection of juvenile fish to a standard indicator by the modernization of individual elements of fish protection of ameliorative water intake of irrigation systems. The design of an integrated fish-protecting structure with a logging boom adapted to hydrology and the rhythm of migration of juvenile fish from irrigation sources has been proposed. The results of studies on a physical model, taking into account the costs of the reclamation system, show an increase in the efficiency of the combined fish protection structure with a harbor for reclamation water intakes in the range of 78,5–84,0 %, depending on the relative flow rate on the shelf of the sanctuary.

We used the data of observations presented in the reports of the FSBI «Head office «Kubanmeliovodhoz» and the results of laboratory tests on the physical model in the scale 1:20 of the new IFPF with the boom structure. The effectiveness of the model was evaluated using simulators for 3 groups of fish fry. The research data were processed using well-known methods of the mathematical analysis. The research methodology is justified which allows taking into account the concentration of young fish in 1 m3 when performing laboratory experiments.The investigations showed that the improvement of the efficiency with the boom structure is achieved due to the additional bottom threshold. The threshold directs the bottom stream with the fish fry to the trampoline where there is an airlift in the form of a bubble curtain, making the young fish to jump in the fish-reception holes of water-permeable shields. A new design IFPF is developed with a boom which provides a protection effect for fish fry formed according to the swimming ability which allowed establishing sizes of elements of fish protection structure.

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