MODERN TRANSFORMATION OF SEASONAL RUNOFF DISTRIBUTION OF THE SIVERSKYI DONETS RIVER BASIN

Abstract

The annual runoff distribution of the Siverskyi Donets River Basin in the period of modern climate change was estimated. The annual runoff distribution of the Siverskyi Donets Basin was researched for two characteristic periods (from the beginning of observations to 1988 and from 1989 to 2018). The assessment was performed for three water year types: wet year, average year and dry year. The research was performed for three groups of rivers depending on their affiliation to a particular part of the Basin. During the research, the average monthly runoff of the hydrological gauges, which we selected for the study were averaged. The annual runoff distribution was leveled in the current period. The Siverskyi Donets Basin is characterized by the peculiar physico-geographical conditions, so the annual runoff distribution is somewhat different for different part of the Basin. Differences in the annual runoff distribution of the right-bank tributaries, the left-bank tributaries and the Siverskyi Donets River were revealed. For the left-bank tributaries, which are less affected by anthropogenic load, climate change has led to a significant increase in runoff of the winter and summer-autumn low period. For the right-bank tributaries of the Siverskyi Donets, flowing within the industrial part of Donbas, the share of low period runoff has not changed, or even decreased. This is due to the reduction of mine drainage, due to the reduction of industrial production in the region. Instead, the share of autumn-winter period in the annual runoff has increased for the right-bank tributaries and the Siverskyi Donets River itself. It is established that the share of spring floods from the annual volume of runoff has significantly decreased and the share of the summer-autumn period for the rivers of the Siverskyi Donets Basin in the modern period has increased. The winter runoff of the left-bank tributaries of the modern period is characterized by an increase. The right-bank tributaries of the Basin are characterized by a decrease in winter runoff. Currently, in dry years, spring flood is practically not allocated on the annual hydrograph; the share of runoff in the limited months has significantly increased. At the present stage of climate change, the annual runoff distribution of the Siverskyi Donets River Basin has undergone significant changes.