The aim of the research was to substantiate floodplain spawning at small and medium rivers of the steppe zone of Russia. The hydrological regime of floodplain spawning was studied for small rivers Krepkaya and Bolshoy Nesvetay and medium river Tuzlov in the basin of the Don River. The research resulted in determination of calculated fishery discharge of the rivers which can provide hydrological regime of floodplain spawning satisfying the requirements for reproduction of phytophilous fish by the depth of flooding, duration, and temperature regime. Calculated fishery discharge was determined on the base of field study for particular sites of the rivers including stream canal and flooding floodplain. It is established that, depending on watershed area, favorable hydrological and temperature regime at natural floodplain spawning in the year with runoff probability of 25 % can be formed by organizing special fishery discharge by the volume of 31.6 to 42.9 % from yearly runoff. In the conditions of comprehensive use of watershed and observed recently water scarcity, this is almost impossible. To solve the problem the authors of the article have developed the construction of artificial spawning for phytophilous and lithophilic fish species with controlled flooding regime of the floodplain. Forming backwater of the water level in the river by longitudinal restricted dams, the construction creates spawning, artificially flooding for required period, which can operate in the year of runoff probability 25 % without special discharges.
Keywords: floodplain spawning, hydrological regime, reproduction of phytophilous fish, small and medium rivers, fishery discharge.
