ИСТИНА

The remnants of the ancient rivers smaller than the modern ones are widespread in the floodplains of lowland rivers in Northern Eurasia. The largest number of floodplain segments with small oxbows is found in the coniferous forests in the north-eastern European Russia. The available radiocarbon dates show that such river channels were active during the Atlantic period of the Holocene. The hydro-morphometric methods were applied to calculate the mean annual discharges of these rivers. The lowest discharges were in the basins of the Vyatka and middle Irtysh rivers, about 40–50% of the modern values. In the other basins discharges were higher, but still less than the recent ones. During the Holocene optimum, water runoff from the northern mega-slope of the East European Plain was about 180 km3 yr–1, which is 30% less than the present runoff from the same drainage area. The annual runoff in the Volga River basin was ~134 km3 yr–1, which is about 50% of the present value. The runoff in the Don and Dnieper basins during the Holocene optimum was 40% less than the present one and that in the Ob and Irtysh basin – 30% less than the present one. If we accept the hypothesis that the Holocene optimum represents a climatic analogue of the global anthropogenic warming of the 21st century, the obtained estimates can be used as the scenario of future water resources in Northern Eurasia.