This study used the standardized precipitation index (SPI) and the standardized runoff index (SRI) to analyze dry and humid conditions in the hill-country catchment area of the Laborec River (Slovakia) over a period of 50 years (1970–2019). Analysis of the SPI and SRI over various time scales showed the occurrence of wet periods (index > 1.0) that were associated with precipitation exceeding the long-term norm, and dry periods (index below −1.0), which were the result of small amounts of precipitation. Analysis of the correlation between the SPI and SRI on different time scales revealed that the catchment showed a weaker response to precipitation over short time scales (1 and 3 months) and a stronger response over longer accumulation periods (6, 9, and 12 months). The highest annual correlation coefficient (r = 0.72) was recorded between SRI-6 at the Humenne hydrometric station and SPI-9 at the Medzilaborce meteorological station in the upper part of the catchment area. The strongest annual correlation (r = 0.69) was obtained between the Izkovce and Kamenica stations in the lower part of the catchment area. As shown by the cross-relationships examined over different periods of accumulation of flows and precipitation, hydrological droughts appeared as a result of the occurrence of meteorological droughts with a three-month delay. The conducted analysis showed that in the case of the Laborec river catchment area, there was a strong correlation between the occurrence of meteorological drought and hydrological drought.

This study examines the trends in air temperature, precipitation and flow rates over a 50-year observation period (1961–2010) and compares two periods, 1961–1985 and 1986–2010. The research was carried out in terms of annual and monthly values. The research area is the Hornad River in Slovakia. The main aim of the study was to examine the evolution of precipitation, air temperature and flows in the Hornad River catchment area, as well as to identify the regions (sub-catchments) most vulnerable to climate change. Increasing trends in air temperature in the years 1961–2010 were found to be statistically significant (the Sen’s slope was between 0.0197 and 0.0239). On the other hand, a statistically significant downward trend in flows was recorded only at the Stratená station (a small mountain catchment, where the Sen’s slope was −0.0063). The remaining upward and downward trends were not statistically significant. Greater differences in the course of the trends were recorded on a monthly basis in individual multi-years. Increasing trends in air temperature were statistically significant from May to August in the period 1961–2010. No trends in precipitation were recorded in the period 1961–2010, and only an upward trend in precipitation was recorded in June from 1986–2010.

Drought monitoring has become a crucial issue around the world due to the increasing climate change. Numerous drought indices can be used for the analysis and predicting the interarrival time of different droughts. In the current study, spatial and temporal variability of droughts in East Slovakia are analyzed using RDI and SPI calculated in 3, 6, and 12 timescales reflecting various physical types of droughts. Drought analysis is done for data from seven meteorological stations for 50 years covering the period from 1972 to 2022. The 3 months SPI and RDI are used to detect the short-term/meteorological drought, 6 months SPI and RDI are used to detect the mid-term/agriculture drought but 12 months SPI or RDI are used to detect long-term/hydrological drought. ArcGIS Pro is used to represent the spacial distribution of all the results.The drought trends were analyzed using Mann- Kendall non-parametric statistical test. The occurrence of historical drought was also clasified according to their severity (moderate, severe and extreme drought). The results show a good relationship between short-term and mid-term SPI and RDI. However, the results of RDI-12 has a smaller time interface, ie drought identification is faster than with SPI-12 which indicate that RDI-12 is further sensitive than SPI-12. Generally, RDI gave better results than SPI highlighting the importance of considering evapotranspiration in drought assessments which is important when identifying long-term drought. Mann–Kendall test identified the significant negative trend in series of RDI 6, 12 time scales in Kamenica and Cirochou station. Implementing measures to minimize the negative effects of mid and long-term droughts on surface and groundwater levels, as well as on aquatic fauna and flora, is important for the area around the Kamenica and Cirochou station.

Climate change has a significant impact on the local and regional hydrological regime. In this study, the hydrological regime and variability of flows in the Torysa river basin were investigated for the period 1973-2020. The flows were evaluated by the RBI index. The results showed that the Torysa river has a large flow variability.

The paper evaluated the mean daily discharges at Hnilec River sub basin, which is located in the Hornád basin in eastern Slovakia. The daily flows were characterized based the graphical method FDC (flow duration curves). This method has a long history of use in water engineering, hydropower, planning and water use. The flows at three river meter stations in the Hnilec River and the anthropogenic impact of a reservoir on the flows in the river basin in the observed period were investigated.