ИСТИНА

According to the geological data, the Caspian Sea raised at the beginning of the Late Glacial up to +50 m. This level was controlled by the altitude of the sill in the Manych Strait composed of erodible deposits. When the water from the Caspian Sea began to flow through the Manych Strait to the Black Sea, this sill was eroded to the altitude +22 m. The level of the Caspian Sea dropped and the sea volume decreased from 132 to 109 thou. km3. The duration of the level drop was controlled by full-capacity discharge in the strait about 50-60 thou. m3 s–1. It lasted for only 20-30 years. After this event the connection between the seas was possible only when the volume of the Caspian Sea exceeded 109 thou. km3. Water budget calculations for the Late Glacial (Sidorchuk et al., 2009) showed that after about 18 kyr B.P. there could be two main phases of such connection. The first phase was during about 2000 years following the sill destruction at the period of high water flow from the Volga River basin with the maximum annual flow volume from Caspian to the Black Sea about 80 km3. The second one was at the transition from the Oldest Dryas to Bølling with the maximum annual flow volume up to 120 km3. At the both periods the connection was intermittent due to unstable water budget of the Caspian Sea.