EXTREME WATER CONTENT IN THE DON RIVER SYSTEM: MODERN ASPECTS

Abstract

In the current climatic conditions, the genesis of river runoff extremes in the Upper Don basin is changing. In the formation of maxima, the dependence on direct runoff-forming factors is decreasing, with the increasing role
of underlying surface factors. The trigger for the changes is active heating of the atmosphere. The aim of this study is to
analyze the modern features of the formation of maximum water discharges in the Upper Don basin.

The initial information on maximum water discharges was systematized for 24 hydrological posts for the period
from the beginning of their operation until 2022. The data were taken from official sources of hydrological information
and electronic resources of the AIS GMVO for 2008–2022. The study employed methods of statistical processing as well
as graphical and analytical interpretation of spatiotemporal variability of hydrological characteristics.
The dynamics of maximum water discharges confirms the tendency of decreasing flood maxima and flood volumes
with an increase in duration by 7–10 days. Flood maxima on the main river Don, right-bank tributaries of the Don, and
the Khopra coincide in time, whereas on the left-bank tributaries of the Don and the tributaries of the Khopra, there is no
consistency in years. It has been established that in the formation of water content extremes on medium-sized and large
rivers the leading role can belong to rain floods, and not only to snow floods, as was the case previously. In 2016 and
2022, water content extremes on the Bityug River – Bobrov town and the Don River – Liski town were of rain origin.
The modern genesis is a consequence of climate warming and the reaction of river runoff.
The revealed features of the water regime and the formation of water content extremes make it possible to state
that, with further climate dynamics, the peculiarity of rain floods’ participation in the formation of extreme water content
on large and medium rivers can potentially become a regularity. Obviously, this fact should be reflected in the regulatory
documents concerning the calculation of the main hydrological characteristics.