The analyses of the monthly discharges in Slovakia by the hydrological exploratory methods

The detection of changes involves detailed analyses of hydrological data in order to prove the character of the changes. This paper focuses on an analysis of average monthly discharges of 14 stage-discharge gauging stations in Slovakia. The measured period is from 1931 to 2016. The using approaches are hydrological exploration methods, which were created by hydrologists due to attempt to describe the behaviour of hydrological time series. The methods have been used to identify a change point using the analysis of residuals, Pettit´s test and the analysis of the relationship of the mean annual flow deviations from the long-term annual flows and the deviations of the average monthly flows from the long-term average monthly flows. A considerable number of change points was identified in the 80's and 90's. The results of the analyses show changes in hydrological regime, but to confirm the outcome accuracy, it is necessary to examine also other hydrological and meteorological elements as e.g., precipitation and air temperature.