VARIABILITY OF THE HYDROLOGICAL REGIME OF SMALL AND MEDIUM-SIZED RIVERS IN THE VOLGA BASIN OF THE OKA-DON LOWLAND

Abstract

This article examines the transformation of the water regime in the rivers of the Volga basin in theterritory of the Oka-Don lowland. The aim of the study is to analyze changes in the hydrological regime of the Volgabasin rivers in the Tambov region for the period from 1953 to 2021.Mathematical, statistical, analytical, and geographical methods were used in the research. Primary observationsdata from hydrological journals for 69 years were digitized for 5 hydrological posts in the Tambov region (Kuzmino-Gat, Knyazhevo, Znamenka, Pudovkin, Rozhdestvenskoe) located on 4 rivers (Tsna, Bolshoy Lomovis, Karian, Chelnovaya).The data were provided by the Tambov Center for Hydrometeorology and Environmental Monitoring.Data analysis was carried out for three equal time periods: 1953–1975, 1976–1998, 1999–2021. The results obtained indicate a gradual decrease in the share of spring flooding in the total annual runoff over the period from 1953 to2021.The authors note a slight increase in the duration of the high water period on the studied rivers.As a result of the study, a single schematic map was compiled showing the percentage of runoff during the springflood in relation to the annual runoff on the rivers of the Tambov region over the three time periods. The map reflects aclear decrease in the proportion of flooding in the modern period in comparison with earlier periods.