Reconstructing Lake Onego evolution during and after the Late Weichselian glaciation with special reference to water volume and area estimations

GIS-based reconstructions of Lake Onego development in the Late Pleistocene and the Holocene are presented. Reconstructions originated from the ideas of the Lake Onego depression deglaciation model proposed by I. N. Demidov and the isobase data of E. I. Devyatova. Twelve digital paleogeographic maps were developed and now are available on-line. The reconstructions for different time periods were unified, had a spatial resolution 90m and a strict geographic conjunction. Paleogeographic maps were verified in relation to hand-drawing images of I. N. Demidov and E. I. Devyatova and by matching lake shoreline with a position of archaeological sites both in qualitative and quantitative manner. Area, volume, maximum, mean depth and dynamics of water fluctuation of Lake Onego was determined at twelve stages of its development. The discrepancies in ice-marginal positions and time scales were found to be major factors affecting the area and volume uncertainties between present and previous studies. Awareness of the lake's shoreline position allows us to determine areas where human settlement was possible, which increases our chances of discovering new archaeological sites.