The aim of the paper is to estimate the pollutants input from irrigated fields into collector-drainage water on the basis of mathematical models. The acutenance of the problem is the lack of updated data on the composition of the collector-drainage water, taken from any irrigated field, and the lack of modern developments, allowing to identify the source of contamination reliably. Violations in the drainage systems operation in Central (irrigated) area of the Rostov region contribute to the uncontrolled flow of contaminated groundwater into surface waters. The assessment of the pollutants presence in the run-off was conducted in eco-analytical laboratory of Russian Research Institute of Land Improvement Problems. Based on the analysis of the results revealed it was stated that sulfates (an average of 10 MPC = maximum permissible concentration), sodium ions (3 MPC) and manganese (2.5 MPC) determine the total mineralization of waste; predominant type of salinity is sodium sulphate. Chemical analysis of collector-drainage water for 2014–2015 made it possible to prove that the mathematical models show a close correlation between salinity waters and their ionic composition. The determined dependence is often close to the functional one. The dependencies between the salt content of separate ions and mineralized collector-drainage water for each irrigation system are individual at the uniformity of landscapes and hydrogeological conditions. Thus, the joint mathematical processing of data on drainage water pollution from irrigation systems located in different natural and agricultural conditions, but treated as a single object, causes a false inaccurate information due to lowering correlation ratio between the content of individual ions and their amount. It complicates the geographical location identification of a particular source of pollutants.
Keywords: collector-drainage water, contaminants, natural drainage, water salinity, ionic composition, the correlation coefficient.
