T7 Paleohydrology and Global Change (Posters)
THEMES ARISING FROM PALEOHYDROLOGICAL RESEARCH IN HIGH LATITUDES AND THE TEMPERATE ZONE
Paper number: T7-2
Program: Technical Sessions
Time: 1:30 PM – 4:30 PM
Authors
Abstract
During the Lateglacial and the early Holocene major transformations in water storage and drainage pattern occurred. Rapidly retreating ice sheets and permafrost left new topography over which lake basins with surficial storage were developed, then being subsequently modified with the gradual formation of a new drainage pattern, expansion of bogs and overgrowing of lakes. In continental climate areas permafrost still dominates. With extension of forest communities rivers changed their regime and their channels shifted from a braided to a meandering pattern.
The cooler and wetter phases, clearly evident during the Holocene coinciding with decreases in solar activity and with high frequencies of volcanic eruptions, are characterised by higher frequencies of extreme floods and their clustering. Rivers responded to these conditions by straightening and braiding of their channels, especially in mountain headwater catchments, where lowering of vertical climatic vegetation belts is also observed.
Special attention should be concentrated on human intervention, which initially caused an acceleration of runoff, increase of sediment load and aggradation, but later in the last century various human activities directly provoked opposite tendencies.