Ecological Systems and Devices Annotation << Back HYDRAULIC CALCULATIONS OF A FISH SCREEN COMBINED WITH A FISHWAY O.G. Natishvili, G.V. Gavardashvili, I.G. Kruashvili By using the general differential equations of one-dimensional motion of water current with variable discharge along the route for non-prismatic canals, the work gives the theoretical method to calculate the structure made up of a fine self-purifying fish grid and fishway and manufactured as an open channel used for waste and sludge disposal. The gained equations give the possibility to calculate the needed inclination in the trapezoid plan of the grid for the motion of a transitional current above the grid with permanent speed and depth ensuring the passage of the main fi sh species both, from the tail race upwards and vice versa, preventing the death of young fish. Keywords: fishway; self-purifying fish grid; one-dimensional differential equations; permanent speeds and depths along the route; specifi c discharge. Contacts: E-mail: agr.otar@science.org.ge, E-mail: givi_gava@yahoo.com, E-mail: iraklikruashvili@yahoo.com Pp. 25-31.