The objective of the research was to increase the efficiency of the irrigation systems of the Rostov region. It is established that the water volume discharging at the emptying of the diversion canals of seven large irrigation systems is 51.2 million m³. Assuming the irrigation rate 1500-2500 m³/ha, this water volume enables additionally to irrigate the area 20.5 to 34 thousand ha, which equals to 10-17 % from all irrigated lands at the given irrigation systems. Average annual melt water volume from catchment areas adjacent to diversion canals in the Rostov region is 68.1 million m³. Assuming the irrigation rate mentioned above, such water volume can irrigate an area from 23 to 45 thousand ha or 22-25 % of the currently irrigated lands. While the additional expansion of the irrigated area on the base of complex use of local flow and irrigation return flow, the most prospective technology is the improved estuary irrigation technology which enables to increase the efficiency of irrigation systems by improving the degree of efficiency, coefficient of land use, and coefficient of water use. Decisionmaking algorithm for organization of estuary irrigation comprises the localization of sites where technological irrigation overflow and places of local flow concentration occur; calculation of the volumes of overflow and local flow water; determination of the land use type; calculation of potential irrigated area; and economic efficiency assessment. The criteria and indicators for using the estuary irrigation technology were established: allowable depth of groundwater for fresh water – 1.5 m and for salt – 3.0 m; allowable groundwater mineralization is 3 g/l; optimal slope – up to 0.02; water absorption rate in soil for the first hour – 1-5 m per hour. Technical realization of the estuary irrigation technology is possible on the base of developed engineering solution, a key element of which is the differentiated block of water allocation enables to use waters either from local flow from higher situated catchment area, or from the regular irrigation source including overflow waters from canals and ponds.
