Present-Day Hydrological and Hydrogeological Regularities in the Formation of River Floodplains in the Middle Don Basin

Abstract—The results of studies of floodplain landscapes of the Don tributaries in its middle reaches are presented. The rivers under consideration are the Khoper, Medveditsa, Ilovlya, and Chir, as well as the tributaries of the Khoper―the Kosarka and Buzuluk. At the preliminary office stage, hydrological data on water levels and spring flood discharges over 1988–2018 were analyzed, and the inundation areas were determined by satellite images. In July–October 2019, field landscape-ecological studies were carried out, including instrumental profiling, soil and geobotanic studies, and evaluation of the depth to groundwater table. The floodplains of the Middle Don tributaries were found to have formed under the conditions of much higher water abundance in the rivers. The probability of the spring inundation of the floodplain does not exceed 10%. Under such conditions, cereal grass communities form on the high and, partly, middle floodplain, their composition being close to the zonal steppe vegetation of nearby areas. Some species in the vegetation indicate to a minor salinity of soils.