The aim of study is the justification of the dilution zones extent by waste water re-filling of irrigation channels. The urgency of wastewater reuse on irrigation systems in Rostov region lies in the fact that silting basin of Tsimlyansk reservoir and the high traffic load on the river Don doesn’t allow reliable irrigation water intake in the irrigation canals network during the irrigation season as needed. At the same time a large amount of process vents and collector-drainage water is discharged into the intakes inefficiently. During the analysis of the solutions obtained it’s been found out that the field non-uniformity of the contaminants’ concentration vertically should be considered only on a small area below the point of effluent intake. Determination of the section length of the concentration pattern vertically does not play a key role in problem solving. Therefore, in the further concentration pattern should be considered as two-dimensional. The existing flows in irrigation canals have a layered kinematic structure, the characteristic feature of which is the interaction between a flow and a bed. Under the influence of moving masses, canal bed eventually becomes deformed and various morphological formations which affect the flow turbulence and the velocity field structure appear. With different stagnant areas in storage pond the flow’s multilevels affect the mixing and dilution of possible contaminants. The substantiation for the determination of the dispersion coefficient and assessment of its dependence on the velocity field is done. It is recommended to determine the distance to the complete mixing cross section by taking into account the turbulent dispersion empirical coefficients. The calculation data can show a satisfactory agreement with the field data, if the included empirical coefficients are clarified through preliminary experimental research on every object under consideration.
Keywords: waste water, irrigation system, dilution zone, contaminants, turbulent dispersion.
