Impact of Middle Pleistocene (Saalian) glacial lake-outburst floods on the meltwater-drainage pathways in northern central Europe: Insights from 2D numerical flood simulation
Creators: name: Lang, Jörg
name: Alho, Petteri
name: Kasvi, Elina
name: Goseberg, Nils
name: Winsemann, Jutta
Publisher: name: London : Elsevier Ltd.
Year: 2019
Subjects: subject: Glacial lake-outburst flood
subject: Ice-dammed lakes
subject: Meltwater-drainage systems
subject: Middle pleistocene glaciations
subject: Numerical flood simulation
subject: Palaeotopography
subject: Drainage
subject: Floods
subject: Glacial geology
subject: Glaciers
subject: Ice
subject: Numerical models
subject: Shear flow
subject: Shear stress
subject: Flood simulation
subject: Glacial lake outburst flood
subject: Ice-dammed lake
subject: Meltwater drainage system
subject: Middle Pleistocene
subject: Lakes
subject: flash flood
subject: glacial lake
subject: glaciation
subject: ice margin
subject: ice sheet
subject: ice-dammed lake
subject: meltwater
subject: outburst
subject: paleotopography
subject: peak discharge
subject: Pleistocene
subject: proglacial environment
subject: Saalian
subject: simulation
subject: two-dimensional modeling
subject: Atlantic Ocean
subject: Central Europe
subject: Germany
subject: Netherlands
subject: North Sea
subject: Dewey Decimal Classification::500 | Naturwissenschaften::550 | Geowissenschaften

description: The terrestrial margins of the Middle Pleistocene ice sheets in northern central Europe were characterised by the formation of extensive ice-dammed lakes, which were controlled by the blockage of spillways by the ice margin. The largest ice-dammed lake had a volume of ∼224 km³ and formed in a late stage of the first Saalian ice advance (MIS 6) in central Germany. The failure of the ice dam in the bedrock-outlet channel triggered a major glacial lake-outburst flood. Flood-related erosional and depositional features include large-scale scours, trench-like channels, streamlined hills, giant bars and run-up deposits, indicating a wide spreading of the outburst flood in an early stage and the incision of trench-like valleys in a later stage. The incision of large valleys in the proximal flood pathway strongly impacted the regional drainage system by providing an efficient drainage network. The trench-like channels initiated by the lake-outburst flood became a crucial part of the ice-marginal drainage and subsequent fluvial system. The reconstructed outlet hydrographs imply peak discharges of 465,000–673,000 m³s −1 . The numerical simulation indicates flow depths of up to 87 m, flow velocities of up to 7 ms −1 , peaks of the bed-shear stress of 2500 Nm −2 and the inundation of large parts of northwestern Germany and the northern Netherlands. The numerical simulation of the outburst flood was conducted on both the modern digital elevation model and on palaeotopographic models, representing the palaeotopography prior to the outburst flood and during maximum flood-related incision, respectively. Distally, the outburst flood probably followed an east-west trending route through northwestern Germany and the central Netherlands into the ice-dammed lake in the southern North Sea Basin. The added water volume might have led to the overspill and drainage of the proglacial lakes in the central Netherlands and the North Sea Lake in a chain reaction, eventually opening an east-west trending meltwater-drainage pathway along the southwestern margin of the decaying ice sheet. © 2019 The Authors