Assessment of the hydro-ecological situation of the Verkhno-Ivachivsk Reservoir in Ternopil using the fuzzy logic apparatus

Abstract

The work purpose is to investigate the water parameters of the Verkhno-Ivachivsk water intake, Ternopil and develop a model of water quality assessment and management. Common methods of hydroecological studies of surface water were used to determine hydrochemical indicators. A model based on fuzzy logic and neural networks implemented in Matlab software was used to assess the water quality of the water intake. As a result of a complex hydroecological study of the water intake, which provides the drinking water majority supply in Ternopil, the content of the main pollutants (compounds of nitrogen, phosphorus, petroleum products, phenols, surface active agents) was determined (May, June, November, January 2019-2020). We compared the obtained indicator values with the ecological regulations and drinking water quality standards and we also assessed the ecological danger by the content of individual substances and the ecotoxicological situation in general. It was established that the water is slightly alkaline, which contributes to the presence of carbon dioxide in the form of a hydrogen carbonate ion, ensuring an environ-mentally acceptable gas regime of water. The reason for water alkalinity is the rotting of organic substances from the agricultural sector. The water quality according to the phosphate indicator is good even in the conditions of intensive supply of phosphates with sewage, due to their transition into insoluble forms and accumulation in sediments (silt), which is also facilitated by the low alkalinity of the water. An increased content of nitrogen compounds (ammonium, nitrates) in the water was revealed. Pollution and disruption of the nitrogen-containing compound cycle can be associated with the inflow of nitrogen compounds from surface runoff water and municipal and household washes, the organic substance decomposition in the agricultural sector and a violation of the production and destruction process ratio. The aquifer significant pollution by anthropogenic origin organic substances is reflected in the value of BOD5 indicator, which is higher than the permissible level. The established values indicate high organic pollution and correlates with the formation of significant ammonia amounts which is a product of anaerobic and aerobic organic substance oxidation. After defuzzification of all neural connections in Matlab program we obtained a model for evaluating the quality of water intake at an average level with an indicator of 1.52, which corresponds to the rating scale - an average level in the range (1.36-2.18).