Hydromorphological and hydroclimatic methods were used to reconstruct the former surface runoff from the East European part of the Black Sea drainage basin. Data on the shape and dynamics of the last Fennoscandian ice sheet were used to calculate meltwater supply to the headwaters of the Dnieper River. The channel width and meander wavelength of well-preserved fragments of large paleochannels were measured at 51 locations in the Dnieper and Don River basins (East European Plain), which allowed reconstruction of the former surface runoff of the ancient rivers, as well as the total volume of flow into the Black Sea, using transform functions. Studies of the composition of fossil floras derived from radiocarbon-dated sediments of various origins and ages make it possible to locate their modern region analogues. These analogues provide climatic and hydrological indexes for the Late Pleniglacial and Late Glacial landscapes. Morphological, geological, geochronological, and palynological studies show that the landscape, climatic, and hydrologic history of the region included: (1) a cold and dry interval close to the Last Glacial Maximum characterized by high meteoritic surface runoff supplemented by meltwater flow from ice-dam lakes; (2) a warmer humid interval at the end of the Late Pleniglacial with very high surface runoff and formation of extremely large meandering channels, combined with a short event of substantial inflow from the Caspian Sea; and (3) a period from the Oldest Dryas to the Preboreal of nonsteady surface runoff decrease, and transformation of large meandering channels into smaller ones against the background of climate warming.