References of "Poesen, J"
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See detailFluvial architecture of Belgian river systems in contrasting environments:implications for reconstructing the sedimentation history
Notebaert, Bastiaan; Houbrechts, Geoffrey ULg; Verstraeten, G. et al

in Netherlands Journal of Geosciences - Geologie en Mijnbouw (2011), 90(1), 31-50

Accurate dating is necessary to get insight in the temporal variations in sediment deposition in floodplains. The interpretation of such dates is however dependent on the fluvial architecture of the ... [more ▼]

Accurate dating is necessary to get insight in the temporal variations in sediment deposition in floodplains. The interpretation of such dates is however dependent on the fluvial architecture of the floodplain. In this study we discuss the fluvial architecture of three contrasting Belgian catchments (Dijle, Geul and Amblève catchment) and how this influences the dating possibilities of net floodplain sediment storage. Although vertical aggradation occurred in all three floodplains during the last part of the Holocene, they differ in the importance of lateral accretion and vertical aggradation during the entire Holocene. Holocene floodplain aggradation is the dominant process in the Dijle catchment. Lateral reworking of the floodplain sediments by river meandering was limited to a part of the floodplain, resulting in stacked point bar deposits. The fluvial architecture allows identifying vertical aggradation without erosional hiatuses. Results show that trends in vertical floodplain aggradation in the Dijle catchment are mainly related to land use changes. In the other two catchments, lateral reworking was the dominant process, and channel lag and point bar deposits occur over the entire floodplain width. Here, tracers were used to date the sediment dynamics: lead from metal mining in the Geul and iron slag from ironworks in the Amblève catchment. These methods allow the identification of two or three discrete periods, but their spatial extent and variations is identified in a continuous way. The fluvial architecture and the limitation in dating with tracers hampered the identification of dominant environmental changes for sediment dynamics in both catchments. Dating methods which provide only discrete point information, like radiocarbon or OSL dating, are best suited for fluvial systems which contain continuous aggradation profiles. Spatially more continuous dating methods, e.g. through the use of tracers, allow to reconstruct past surfaces and allow to reconstruct reworked parts of the floodplain. As such they allow a better reconstruction of past sedimentation rates in systems with important lateral reworking. [less ▲]

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See detailTracking landslide displacements by multi-temporal DTMs: A combined aerial stereophotogrammetric and LIDAR approach in western Belgium
Dewitte, Olivier ULg; Jasselette, J. C.; Cornet, Yves ULg et al

in Engineering Geology (2008), 99(1-2), 11-22

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See detailCharacteristics of the size distribution of recent and historical landslides in a populated hilly region
Van den Eeckhaut, M.; Poesen, J.; Govers, G. et al

in Earth and Planetary Science Letters (2007), 256(3-4), 588-603

Despite the availability of studies on the frequency density of landslide areas in mountainous regions, frequency-area distributions of historical landslide inventories in populated hilly regions are ... [more ▼]

Despite the availability of studies on the frequency density of landslide areas in mountainous regions, frequency-area distributions of historical landslide inventories in populated hilly regions are absent. This study revealed that the frequency-area distribution derived from a detailed landslide inventory of the Flemish Ardennes (Belgium) is significantly different from distributions usually obtained in mountainous areas where landslides are triggered by large-scale natural causal factors such as rainfall, earthquakes or rapid snowmelt. Instead, the landslide inventory consists of the superposition of two populations, i.e. (i) small (<1-2 . 10(-2) km(2)), shallow complex earth slides that are at most 30 yr old, and (ii) large (> 1-2 . 10(-2) km(2)), deep-seated landslides that are older than 100 yr. Both subpopulations are best represented by a negative power-law relation with exponents of -0.58 and -2.31 respectively. This study focused on the negative power-law relation obtained for recent, small landslides, and contributes to the understanding of frequency distributions of landslide areas by presenting a conceptual model explaining this negative power-law relation for small landslides in populated hilly regions. According to the model hilly regions can be relatively stable under the present-day environmental conditions, and landslides are mainly triggered by human activities that have only a local impact on slope stability. Therefore, landslides caused by anthropogenic triggers are limited in size, and the number of landslides decreases with landslide area. The frequency density of landslide areas for old landslides is similar to those obtained for historical inventories compiled in mountainous areas, as apart from the negative power-law relation with exponent -2.31 for large landslides, a positive power-law relation followed by a rollover is observed for smaller landslides. However, when analysing the old landslides together with the more recent ones, the present-day higher temporal frequency of small landslides compared to large landslides, obscures the positive power-law relation and rollover. (C) 2007 Elsevier B.V. All rights reserved. [less ▲]

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