Assessment of the hydrogeochemical conditions at the Nikolsky water intake (Liski, Voronezh Region)

Abstract

Introduction: Among the key aims listed in the strategic plan for the development of Liski in the Voronezh Region is the need to improve the living standards in the town. In order to do this, two major tasks have to be completed: ensuring regular water supply and ensuring full compliance of the quality of drinking water to the existing standards. At present, the water supply in Liski is provided by two water intakes: the Bogatoe water intake provides 5.14 thousand m3/day and the Peskovatskoe water intake provides 6.4 thousand m3/day. The long-term requirement in Liski is 15.0 thousand m3/day. The construction of the Nikolsky water intake was necessitated by a shortage and a progressive deterioration in the quality of drinking water produced at the existing water intakes in Liski. Methodology: The water intake site is located 5 km east of Nikolsky village and occupies and area of about 5 km along the right bank of the Don River. The following were identified as promising aquifers: the modern alluvial aquifer, which has a hydraulic connection with the Don River, the Aptian-Cenomanian terrigenous aquifer, and the Devonian terrigenous system. There is a certain hydraulic relationship between these aquifers. At the moment, the hydrogeochemical conditions at the water intake are unfavourable, with a significant excess of iron (up to 18 mg/l in the Quaternary aquifer and up to 3.2 mg/l in the waters of the Devonian system). The waters of the Quaternary aquifer register a constant increase in hardness (up to 12 mg-gE/l). The waters of the Devonian system are also characterized by increased hardness (up to 10.9 mg gE/l). Increased concentrations of manganese of up to 1.02 mg/l were also registered in the Quaternary aquifer. The main source of these elements are natural mineral and organic compounds and systems. In the modern aquifer, the waters are currently characterized by a significant excess in terms of colour and turbidity, which can be accounted for by pumping tests and the likely introduction of colloids and various organic compounds in the drained water. Conclusions: The main reason for the deterioration of the hydrogeochemical conditions in the studied area is an increase in the level of certain indicators of groundwater quality due to the violation of the natural regime of the formation of the chemical composition and the existing geochemical equilibrium. During the pumping process, especially if it is chaotic, the hydrogeodynamic conditions change dramatically. Adjacent structures are involved the zone of artificial drainage. These structures have increased concentrations of calcium and magnesium, the main components that affect the hardness of water. In order to develop recommendations for optimizing the operation of water intake from the existing wells as well as for constructing additional wells, it is necessary to monitor the workflow in the field (the flow rate, its level, and chemical composition), i.e. to perform an appraisal survey.