Modern problems of water quality forming of the Ingulets irrigation system while applying the Ingulets river washing during April-August) and ways to solve them

Abstract

Purpose. To investigate the actual state of the process of water quality forming in the Ingulets irrigation system by washing the Ingulets River for the last 10 years (2011–2020), to identify existing problems and ways to solve them. Methods. System approach and system data analysis, generalization, comparison, feedback, field and laboratory researches. Results. From 2011 to the present times, the Ingulets irrigation system is using the option of forming water quality “Flushing from above for the entire irrigation period”: satisfactory irrigation water quality is forming in the irrigation source – the river Ingulets by making constant releases of water from the Karachunovsky reservoir from April to August expenses 20–9,0 m3/s with a total volume of not less than 120 million m3. A study of the actual implementation of the Regulations of riverbed washing and ecological rehabilitation of the Ingulets River and a study of water quality by chloride content at the Andriyivka hydropost was done. As a result of researches, the percentage of days in which the chloride content in the water of the Ingulets River exceeded the volume of 350 mg/dm3 was determined; 400, 450, 500 mg/dm3 (taking into account the terms of the beginning and the end of washings and taking into account the terms of reaching the water). The percentage of the average annual ratio of days in which the water quality in terms of chloride content exceeds 350 mg/dm3 in 2018–2020 is 68,71%, in 2011–2017 – 17,37%; above 400 mg/dm3, accordingly 33,28 and 2,86%; above 450 mg/dm3, accordingly 20,47 and 0,88%; above 500 mg/dm3, accordingly 14,38 and 0,55%. Conclusions. Researches have shown that in 2018–2020 there was a significant deterioration of the quality of water of the Ingulets River, and consequently irrigation water in the Ingulets main canal compared to 2011–2017, which can lead to negative impact on agricultural products and activate processes of soil degradation. The main reason is the incomplete implementation of the Regulations for riverbed washing and ecological rehabilitation of the Ingulets River, namely the reduction of the costs of flushing water discharges from the Karachunivsky Reservoir and the commissioning of GNS until the moment of achivement of normative water quality in the Ingulets River was reached (2020). It is recommended in future to fix compulsory in the Regulations the maximum concentration of chlorides in the water of the Ingulets River (350 mg/dm3) during the whole irrigation period, to define clearly the real effective mechanism of fulfillment and to control over the fulfillment of the mentioned requirement. Ways of further researches are more complete study of the relationship between the filling of the Svistunov beam with mine waters and water quality in the Ingulets River. Also it is necessary to create an expert system and to organize targeted monitoring of the forming of appropriate water quality in the Ingulets River and in the main canal of the Ingulets Irrigation System.