Younger Dryas flood events: A case study from the middle Warta River valley (Central Poland)

Abstract

The Weichselian Late Glacial sequence composed of Younger Dryas overbank deposits and the Alleröd/Younger Dryas organic-rich series from the Warta River valley, Central Poland, were studied within a project, including sedimentological criteria, analysis of aquatic invertebrates (cladocerans and chironomids) remains and diatoms. The well-dated sequence of events on the floodplain, mainly due to the determination of the age of in situ riparian forest, provided a basis for a reconstruction of local conditions of palaeofloods in a wide context of global climatic changes at the Weichselian decline. The flash floods were largely affected by catchment topography, forest destruction in response to the Younger Dryas cooling, and permafrost reappearance. The floods have been detected as the causative factors in a river style change.