Katynska I. Average annual runoff and its variability on Zacarpathian rivers

The theoretical study and working out of method of calculating of annual runoff rates, coefficients of variation and skewness for the mountainous conditions of Zacarpathian region were completed in this work. In Ukraine these characteristics are still calculated by specification standard SNIP 2.01.14-83, which generalize of calculating of annual runoff rates, coefficients of variation and skewness of time series more than 40 years. It was grounded distribution of annual runoff rates over Zacarpathian territory (i.e. Tisza River basin) by more reliable methodology. It was found out that the almost half of Tisza River area is not covered with data due to the assignment of runoff date to the geometrical centers of individual catchments when the spatial generalization of modules of annual runoff of Tisza River was implemented. This fact significantly affects the ability to determine the calculating characteristics of rivers that are not been studied in the hydrological sense. To overcome these circumstances materials of observations for precipitation were also involved in the addition to the hydrological parameters. It allowed to grounded that part of catchments for which data of observations were not enough and to clarify the method of determining modules of annual runoff. The reduction coefficients to account for the peculiarities of runoff formation in small catchments with a size of less than 20 km2 also worked out and grounded in the work. Issues related to the definition of coefficients of variation and skewness are decided in this work at a modern level. Studies of the characteristics of annual runoff in the Tisza river basin shows that the grounded parameters (rates of runoff, coefficients of variation and skewness) fully corresponds to the requirements of normative documents in Ukraine. Obtained results of qualifying scientific work "Methodology for determining of calculated characteristics of Zacarpathian rivers" have implemented in practical activities of Zacarpathian Regional Center for Hydrometeorology (certificate of implementation from 22.06.2017). The results of studies in Tisza River basin will clarify regulatory base on the regional level, which operates today in Zacarpathian region.