Title: Human impact on floodplain geoecology. A Holocene perspective for the Dijle catchment, Central Belgium
Authors: Broothaerts, Nils
Verstraeten, Gert
Notebaert, Bastiaan
Kasse, Cornelis
Bohncke, Sjoerd
Vandenberghe, Jef
Issue Date: Aug-2013
Conference: IAG International Conference on Geomorphology edition:8 location:Paris date:27-31 August 2013
Abstract: Floodplain deposition rates have increased markedly under influence of human impact throughout the Late
Holocene in many Western and Central European catchments. These variations in sedimentation rates have
changed the geomorphology and ecology of many floodplains. In this study we discuss the human impact and its
influence on floodplain geoecology for the Dijle catchment (760 km²), located in the Belgian loess belt. The
geoecology of the floodplain and the regional vegetation was reconstructed based on sedimentological and
palynological analysis. Age depth models for each of the studied sequences were obtained through 60
radiocarbon dates. Based on statistical analysis of the pollen data (e.g. cluster analysis and canonical
correspondence analysis) human impact in the catchment was quantified. Our data shows that until ca. 2500 cal
BP, human impact was either absent or limited to local disturbances yielding no clear influence on the floodplain
geoecology. The river environment was in a stable phase and consisted of a marshy environment were organic
material could accumulate, which is interpreted as the natural state of the floodplain. From ca. 2500 cal BP
onwards, human impact gradually increased. However, only when human impact in the catchment crossed a
threshold, the floodplain geoecology changed with clearing of the Alder carr forest, the creation of a single
channel river and the dominance of minerogenic overbank sedimentation.Spatial variability in the coupling
between increasing human impact and changes in floodplain geoecology can be attributed to differences in
hillslope-fluvial system connectivity and local differences in human impact. Overall, this study provides new
insights of how river systems respond to environmental change. It also shows that the contemporary morphology
of the floodplains, with a typical meandering river bordered by levees and mineral floodplain deposits, has an
indirect anthropogenic origin.
Publication status: published
KU Leuven publication type: IMa
Appears in Collections:Division of Geography & Tourism

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