SURFACE WATER QUALITY ASSESSMENT FOR IRRIGATION USING HARRINGTON’S DESIRABILITY FUNCTION

Abstract

The research objective is to analyze the existing approaches and develop a generalized assessment methodology for surface water composition, including its physicochemical and chemical-toxicological parameters. The predicted field of water consumption is irrigation. The actuality of the research topic is the key role of irrigation in food problems against the backdrop of global climate change. Harrington's desirability function, a well-known technique of qualimetry was used as an aggregation approach of individual water quality indicators. SAR indicators and the Stabler's irrigation coefficient were calculated as sub-indices. Scales of partial desirability di for each individual parameter of water composition and properties are compiled on the basis of water quality limitations for irrigation. The guidelines of such regulatory documents as Ukrainian State Standard DSTU 2730:2015 Environmental Protection. Quality of natural water for irrigation. Agronomic criteria, and a departmental regulatory document (DRD) 33-5.5-02-97 Water for irrigation. Environmental criteria are the basis for developing quality scales. The procedure of the irrigation water quality index (IWQI) calculation was carried out using our own Python software product WODA v0.6A. On the example of water quality assessment of the Umanka River (Cherkasy oblast), the results of the proposed methodology application in the form of an IWQI according to 18 indicators (a pH, turbidity, total dissolved solids TDS, the main ions of the mineral matrix, phosphates, nitrate nitrogen, total iron, the content of Zinc, Copper, Lead, and Cadmium, Kubel’s permanganate index). It was established that the variability of a pH, turbidity, temporary hardness, and permanganate index were the main influence factors that responded to the overall quality assessment reduction. The qualitative assessment of water quality for irrigation purposes ranged from 73% (good) to 61% (satisfactory). A priori, the river water quality deterioration below Uman city was predictable. The use of the proposed methodology would be useful for the organization of spatio-temporal monitoring, observation data processing, and modeling of water quality according to any set of water composition parameters and properties for various types of water use and consumption.