Study of trends in the time series of maximum water discharges in the Tisza basin rivers within Ukraine

Nowadays, due to global and local climate changes, according to leading experts, the likelihood of extreme natural phenomena increases. One of the dangerous natural phenomena with impacts on humans and the economy are floods. The Tisza River, which originates in Ukraine and flows further through Romania, Hungary, Slovakia, and Serbia, has repeatedly become a source of disasters for the population due to the devastating consequences of floods, which have been increasing in recent years. The purpose of this study is to analyze the long-term series of observations of the maximum water discharge on the rivers of the Tisza basin, within Ukraine. Using the methods of statistical analysis, tendencies in the time series of annual maximum water discharges were investigated, its temporal homogeneity was estimated also, as well as the significance of the trends. Using the method of residual mass curves, high-water and low-water periods were distinguished. We also obtained preliminary dependences of the maximum runoff modules on the catchment areas and their heights, which in the future can serve as a basis for the development of a regional calculation method for determining the maximum runoff of ungauged rivers in the region.