Design Facilities for Air-Lift Fishery and their Effectiveness

Abstract

The withdrawal of a huge amount of water for needs of municipal and agriculture, for industry and energy production significantly affects the reduction of fish stocks and reduce the economic potential of fishery water bodies. To protect aquatic fauna, water diverting structures should be equipped with effective fish protection devices and fish protection structures. At present, a sufficiently large number of various designs of fish protection devices have been developed. However, functioning of many of them cannot be considered as satisfactory. This largely applies to water diverting facilities with a capacity of more than fifteen cubic meters per second, located on the water bodies in South of Russia, where there are rich and unique stocks of valuable commercial fish species. For fish protection structures of large water diverting facilities one of the most difficult is the task to divert the protected fish larva/young fish outside the zone of influence, which is complicated with the speed of a flow in the water intake area. Airlift pumps conform to the requirements about removing young fish to protect them, because airlift pumps do not have moving mechanical parts that might be traumatic for the fish. However, the use of airlift elevators in practice is hampered by the lack of constructive developments and methods for calculating airlifts with a small lifting height, as well as the data about survival of young when these devices are in operation. Constructions used for forced removal of protected fish should ensure the viability of fish at all stages of their movement, with high technical reliability. Options to design an airlift fish diverter have been proposed to be used in fish-protecting devices such as a floating fish-removal line. The rationale to use the airlift elevator as a power plant aimed at removal protected young fish from fish protection structures is provided. We reported about some observed damage caused to fish during their contact with fish protection and fish removal constructions. The necessary conditions, which should be met in order to avoid injuring the protected young fish are described; the results of the study on young fish in the airlift fish elevator are introduced.