Analysis of seasonal changes of thermal stratification in reservoir for drinking water supply (Slovakia, Turček reservoir)

Water reservoirs are important source in supplying inhabitants with drinking water of high-quality. In total, there are 8 reservoirs in Slovakia for drinking water supply purpose. The youngest of them is the Turek reservoir located in the middle of Slovakia, which is also the object of this study. In the article, we deal with the thermal stratification in it during 3 seasons (spring, summer, autumn). Based on the analysis of data provided by the operator of the reservoir from its operation start, it came out that the thermal stratification in the reservoir occurs significantly during the summer. In the given hydro-climatic conditions, it starts at the end of April and ends in October. We also analyzed the existence of the thermocline layer, which occurs mainly in the summer, but also in spring and in autumn, but not so significantly and regularly. Thermal stratification can be classified also by Thermocline Strength Index (TSI) that indicates the steepness of the thermocline or the average gradient of the thermocline layer, so the part of the study was focused also to this indicator.