Temporal and Territorial Variability of Annual and Maximum Flood Runoff of Rivers in the Lipetsk Region

Abstract

The Lipetsk Region has well-developed industrial and agricultural sectors of the economy, for which the water factor is extremely important. The purpose of the research is to study temporal and spatial variability of annual runoff and maximum water discharge of rivers in the Lipetsk Region. Materials and methods. The work is based on the materials of network hydrological measurements of water discharge at gauging stations of the Lipetsk Region and its adjacent territories for the period of operation from the opening and up to 2022 inclusive, taken from the water cadastre, using the electronic resources of AIS GMVO for 2008-2022. Processing of initial information was carried out by methods of mathematical statistics, hydrological analogy and geographical interpolation, geo-information mapping in QGIS and ArcGIS environment. Watersheds were modeled on the basis of the MERIT DEM digital elevation model. The mapped characteristic is the runoff layer for the annual runoff and the runoff modulus for the maximum runoff . Results and discussion. In the long-term variation of annual water discharge of the Don River – town of Zadonsk, the years 1970 and 1979 are distinguished by high water availability with average annual discharges of 203 and 200 m3 /s, respectively, with the mean annual value of 127 m3 /s. Low water availability falls on 1972 with an average annual fl ow rate of 70.0 m3 /s. The period of low water availability since 2007 continues up to the present time. Current renewable water resources of the Lipetsk Region in an average water year are estimated at 2.77 km3 /year, and the average runoff layer over the territory of the region is 115 mm of annual river runoff . The spatial distribution shows a geographical pattern of decreasing runoff layer from north-west to south-east. In the long-term dynamics of maximum spring fl ood discharges, after the exceptionally high-water year of 1970 with a water discharge of 5240 m3 /s, a steady decrease in fl ood maxima continues on the Sosna River – town of Yelets. Similar dynamics is typical for all rivers of the Lipetsk region. The lowest fl ood on the rivers of the Lipetsk region was recorded in 2020 with a peak value of 49.3 m3 /s. The spatial distribution of the maximum runoff module shows meridional extent of isolines on the right-bank tributaries of the Don within the Central Russian Upland and latitudinal extent on the left-bank tributaries within the Oka-Don lowland plain in the range of 390-180 l/s*km2 . Conclusion. Current renewable water resources of the Lipetsk Region represented by the annual river fl ow are equal to 2.77 km3 of local fl ow. In the long-term dynamics of annual water discharge, the high-water years of 1970 and 1979 and the low-water year of 1972 are distinguished. The dynamics of maximum water discharges show a steady decline from the extreme high fl ow of the 1970 fl ood to the exceptionally low fl ow of the 2020 fl ood. The spatial distribution of the runoff modulus shows a meridional direction of isolines on the right bank of the Don and a latitudinal direction on the left bank.