Impact of economic activity on geoecological transformation of the basin of the Zhovtenka River (Ukraine)

Abstract

The article presents the results of the study on the current geoecological condi- tion of the basin of the Zhovtenka River. The study object corresponded to the criteria of a small river, having the length of 42 km and the area of the drainage basin of 293 km2. According to the geographic peculiarities and the level of anthropogenic impact it is a typical small river of the Ukrainian Steppe zone. At the current stage of water management, the river and its tributaries are significantly regulated by artificial aquatic objects – ponds and a water reservoir. The total number of hydrotechnical facilities that form the water bodies is 34 levees. On the river itself, average density of water bodies equals 1 pond per every 2 km of the river length. Such regula- tion contradicts the norms of the current water protection legislation of Ukraine. As a result of fragmentation, the river has turned into a cascade of evaporation ponds. Special ecological threat to water use is the quality of water in the ponds. We determined that due to absence of current and low water exchange, the saline content in water undergoes significant changes. During the field surveys, we collected samples and determined the parameters of mineralization, content of chlorides and sulfates in 10 water bodies. Sampling was carried out during the year in different seasons. We determined that the averaged parameters of mineralization level change within the range of 9.000 mg/dm 3 in spring to 13.000 mg/dm 3 in summer and autumn. The content of chlorides varies within 2.600-3.600 mg/dm 3, sulfates – 4.000-4.800 mg/dm 3 according to the similar seasonal dependence. Due to changes in the climatic conditions and current tendencies of warming and dry climate, decrease in the water resources heightens the risks of irreversible geoecological degradation of the river. Significant regulation and evaporation-caused loss of water leads to rapid shoaling of the water bodies and growth of aquatic-marsh vegetation. The authors suggest an approach to assessment of the level of geoecological transformation of the river basin based on determining quantitative parameters of the constituents of the elements of natural ecosystems and elements of negative anthropogenic impact. We proposed calculation of various coefficients (indicators) which alter the natural condition of water ecosystems, particularly: coefficients of fragmentation, coefficients of urbanization, coefficients of alienation, etc. We present a pos- sibility of using them in relation to the length of the river and hydrographic network, as well as the area of drainage. We determined that percentage parameter of geoecological impact was seen in 94.3% of the area of the drainage basin or 87.4% of the river length. We suggest approaches that would minimize the deleterious impact of economic activity and gradually restore the condition of aquatic ecosystem of the river. The article provides recommendations of using coefficients of geoecological transformation of river ecosystems.