Title: Decadal-scale analysis of ground movements in old landslides in western Belgium
Authors: Dewitte, Olivier ×
Van Den Eeckhaut, Miet
Poesen, Jean
Demoulin, Alain #
Issue Date: Mar-2009
Publisher: Gebrüder Borntraeger
Series Title: Zeitschrift für Geomorphologie vol:53 issue:1 pages:23-45
Abstract: More than 150 large deep-seated landslides have been mapped in the Flemish
Ardennes. Slope instabilities that have occurred in this hilly area of western Belgium during
the last decades correspond to ground movements within these pre-existing landslides. In
order to identify the mechanisms and controlling factors of these ground movements, a good
knowledge of their spatial and temporal distribution is critical. 13 landslides affecting two hills
were investigated based on several DTMs extracted by aerial stereophotogrammetry and spanning
the 1952–1996 period. Vertical ground displacements were measured at each pixel by
DTM subtraction with a confidence value of +- 0.70 m. Horizontal displacements were also
estimated within the landslides and along the head scarps through topographical profiles. Most
observed movements displayed patterns typical of rotational landslides. Vertical and horizontal
displacements vary in magnitude both spatially and temporally, with respective ranges
– 7.4m–+3.8m and 0–14m. Many displacements are materialized in the field. We distinguished
two kinds of slope processes, corresponding to either reactivation at a deeper level or
shallower motion. The former re-uses pre-exiting surfaces of rupture located at depths of ~ 15–
20 m and is associated with the largest subsidence and uplift. They are also smaller reactivations
confined at the landslide head. The other displacements consist in (1) earth flows occurring
in the zone of accumulation sometimes as a consequence of large upslope reactivations,
and (2) small failures occurring randomly. While most movements were triggered by intense
rainfall, their spatial and temporal distribution is strongly related with the nature of the vegetation
cover and the human activity.
ISSN: 0372-8854
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Division of Geography & Tourism
× corresponding author
# (joint) last author

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