GLACIAL MELTWATER VERSUS RIVER RUNOFF AS THE DRIVERS OF THE KHVALYNIAN TRANSGRESSION OF THE CASPIAN SEA (Invited Presentation)
Then what were the sources of water that caused the rise in sea level by more than 100 m? On the floodplains and terraces of the rivers of the Volga basin, big paleochannels, dated to the time of 18-13 ka, are ubiquitous. We used the parameters of paleochannels to estimate the river runoff for more than 120 small basins. Then, by interpolation, maps of the annual paleo-runoff layer were obtained for the entire Volga basin, and from these maps the value of the annual runoff was calculated - 420 km³, i.e. 1.7 times higher than the modern value. This volume is sufficient to maintain the Caspian at the levels of the maximum of the Khvalynian transgression (+ 48 m asl), provided that the value of effective evaporation (evaporation minus precipitation) over the sea was a quarter lower than the current one.
Thus, the main reason for the post-LGM phase of the Khvalynian transgression was the climatically conditioned rise of the river runoff. The role of the influx of glacial melt water could only be a slight decrease in the sea level drop during the LGM.
This research contributes to the RSF Project 19-17-00215.