The Contribution of Glacial Melt Water to Annual Runoff of River Volga in the Last Glacial Epoch

The runoff of glacial melt water into the river system of the Volga and farther into the Caspian Sea is evaluated for the epoch of the last glaciation. Melt water entered the Volga only from the part of the basin that was covered by the Scandinavian ice sheet. During the maximal phase (19–20 thousand years ago) the glacier occupied the farthest upstream parts of the basin, i.e., the Mologa–Sheksna depression (60 thous. km2) and the area near the Volga source and Lake Seliger (5 thous. km2). The volume of melt water runoff was calculated for deglaciation time by three models of the ice sheet. The upper estimate yielded a value of 60–70 km3 per year, and the lower estimate was 15 km3 per year, or 5–25% of the present-day Volga runoff into the Caspian Sea, where the lower value appears more plausible. In that case, even the maximal estimate is not enough to initiate the Khvalynian level rise in the Caspian Sea. In addition, the major part of the time of meltwater inflow into the Volga (~21...~16.5 thous. years ago) corresponds to a regressive state of the Caspian basin. This also does not allow us to consider the glacial factor as the cause of the Khvalynian transgression, the rise of which ~17 thousand years ago fell into the period of a decline of the glacial runoff.