Ecological assessment of surface water quality in a rainless period under the conditions of urban water collection

Abstract

Problem formulation. The global climate warming influences the balance of water reservoirs by lower precipitation, higher evaporation, erosion of soils and other changes. On the territory of Ukraine, the periods without rains, low snow level, warm winters and dry summers, strong winds and dust storms became frequent during the last decades. This led to a change in many hydrological parameters in comparison with the hydrological regimes usual in temperate climates. Therefore, the determination of the ecological assessment of the state of water reservoirs in the conditions of the urban drainage basin in the rainless period is an insufficiently studied and urgent issue. The aim of the article is estimation of quality of the river water in the system of rivers Lopan-Kharkov-Udy on the urban landscale of Kgarkov region. Materials and methods. Field sampling of water and bottom sediments to provide an environmental assessment of the water reservoir; comparison of the results obtained with similar ones obtained for rainy periods and periods of snow melting in different hydrological regimes, and statistical analysis of the measured data. Results. Analysis of the open source data revealed that Kharkov region is among the top three in terms of drinking and technical water needs for various purposes. The region has a maximum possible drought risk index (0.8-1) and high values of water stress indices (2-3) and coastal flood risk (2-3). Water samples taken from different sections of the Lopan and Udy rivers in different seasons showed that some of the parameters exceed the corresponding control values, especially in rainless periods, but in general water quality indices correspond to 1-2 quality classes (depending on the season) for the river Lopan and the 1st class of quality - for the river Udy. Numerical calculations on a mathematical model using the measurement data showed that global warming at 0.5-1° C by 2030 will lead to a significant deterioration in water quality and its availability as the required amount of drinking and industrial water for the region. Scientific novelty. Novel mathematical model is proposed for simple estimations of the water pollution over time at different groth rate of the average temperature accounting for known number of pollutants. Practical significance. The obtained results are useful for further development of the system of water management on urgan territories, testing different hypothesis and scenarios.