Spatial-temporal estimation of water quality according to ecological criteria in the Dnipro-Donbass canal system

The water of the Dnipro-Donbas canal is one of the sources of water supply for the needs of the Kharkiv City and the region, also for irrigation and for ecological releases to the Siversky Donets River. In addition, the canal should provide sufficient water of the appropriate quality for the needs of drinking water supply. The main objective is to find out the trends of water quality changes in the Dnipro-Donbas canal system before and after the water exchange. So, the environmental assessment, which provides information on the water as a part of the aquatic ecosystem, must be performed according to the relevant criteria. An ecosystem approach, which bases on the use of a neural network, is proposed for environmental assessment of the efficiency of water exchange. Based on the common environmental criteria, the assessment of changes in the quality of water resources has been made. Also, a comparative analysis of water quality at selected sections of the Dnipro-Donbas canal during the water exchange in 2016 has been performed. The researches were conducted in three blocks of specialized classifications: the block of salt warehouse, the block of tropho-saprobiological criteria and the block of specific substances of toxic and radiation action, by average and maximum (worst) values. The comparative analysis was done for two periods: August-September (before water exchange) and December-January (after water exchange). According to the results of the comparative analysis of the quality of water resources before and after the water exchange in Dnipro-Donbas canal, improvement of water quality during the period after water exchange was established on the section of the canal from Shulgivka to Orilsky reservoir from “good”, “fairly clean” and “satisfactory”, “poorly contaminated” to “very good”, “clean” with a tendency to approach the category of “good”, “fairly clean”. In Krasnopavliv reservoir the water quality has changed from the “satisfactory”, “slightly polluted” to the category “good”, “fairly clean”. The systematic high level of water pollution in the canal system is determined by the content of sulfates and the indicator of transparency. The water of the Dnipro-Donbas canal is characterized as “bad”, “very bad”, and also “dirty”, “very dirty”.