Comparison of mean daily discharge data for under-mountain and highland-lowland types of rivers

Most Slovak rivers have increasing spring flow followed by a period or two of low flow in the summer, autumn, and, in some cases, winter. The flow rate fluctuations in two different streams in Slovakia are being investigated in this study. The study focused on an under-mountain and a lowland-highland river to investigate the low and peak flow periods and to identify the trends in monthly and annual mean flows for both rivers. Analysing daily mean discharge data from two different types of streams requires the use of a robust normalization approach to verify the comparability between the chosen streams. On both streams, a broad statistical low-flow analysis was performed over different study periods, as well as a hydrological drought analysis utilizing the water-bearing coefficient approach over the period 2010–2020. The evaluation for the foothill river in Slovakia demonstrates that snow melting has a significant impact on annual runoff in the spring months, and both rivers have a low flow period in August, September, and October. Despite the considerable variations in the catchment area, geographical, and hydrological characteristics, drought analysis for the years 2010 to 2020 found a lack of normality and a dry hydrological situation in both streams.