A temporarily changing Holocene sediment budget for a loess-covered catchment (central Belgium)

Abstract

This study presents a Holocene sediment budget for the Nethen catchment, a typical river catchment (55 km 2 ) in the Belgian loess belt. Soil erosion and hillslope sediment storage are quantified by extrapolating detailed data obtained from soil profile truncation studies in three representative zero-order sub catchments. Floodplain sediment storage is estimated by augerings along several transects across the main river and some of its tributaries. The sediment budget shows that ca. 38% of the soil eroded during the Holocene is redeposited as colluvium on hillslopes and in dry valley bottoms. Another 23% of the eroded sediment is now stored as alluvium in the floodplain. The remaining 39% or 21 × 10 6 Mg is exported from the catchment. Dating of both colluvial and alluvial sediment deposits reveals that sediment dynamics between the hillslopes, the dry valley bottoms and the floodplain behave highly non-linearly. Before~500 BC, sediment delivery from the hillslopes to the river channels was near maximum. However, since the onset of significant agriculture in the Late Bronze Age-Early Iron Age, increased rates of soil erosion are only reflected in the colluvium, but not in the floodplain, resulting in very low hillslope sediment delivery ratios. From the Medieval period onwards, soil erosion increased even further, mainly as a result of a further increase in agricultural land use, but now also accelerated floodplain sedimentation took place due to an improved slope-channel coupling and the management of floodplains.

Characterization and quantification of Holocene colluvial and alluvial sediments in the Valdaine Region (southern France)

“…1D), compared to values from other sediment budget studies in Europe. These studies are grouped per country with data from Belgium and a Belgian-Dutch catchment (de Moor and Verstraeten, 2008;Verstraeten et al, 2009b;Notebaert et al, 2011a;Notebaert et al, 2013), France (Macaire et al, 2002), Germany (Seidel and Mackel, 2007;Förster and Wunderlich, 2009;Fuchs et al, 2011;Houben, 2012;Hoffmann et al, 2007) Italy (Borrelli et al, 2012) and Turkey (Dusar et al, 2011). Masses of sediment (10 6 g) are divided by the total catchment area to arrive at the area specific mass (y axis, 10 6 g m -2…”

“…Here, time periods are defined based on important catchment wide geomorphologic changes that are present in the sedimentary record (e.g., Trimble, 1999;Verstraeten et al, 2009b). We determined three depositional periods separated by two periods of hillslope stability and local fluvial incision, which represent the major time periods for the sediment budget.…”

“…The processes are important for shaping the Earth surface and transport sediments and related biochemical constituents from the upland towards the oceans, with intermediate sinks which act as buffers. An increasing number of studies have shown the importance of quantifying the different processes involved over different spatial and temporal scales, in order to understand the sediment cascade (e.g., Trimble, 1999;Hoffmann et al, 2007;Trimble, 2009;Verstraeten et al, 2009b;Notebaert et al, 2011a). Under 'sediment cascade' we understand the transport of sediment through a catchment's landscape, including sources, redistribution pathways and sinks.…”

“…In Europe, the majority of sediment budgets refers to timescales of a years to decades, while sediment budgets referring to timescales of millennia deal with catchment in Germany, Belgium and the Netherlands (e.g., Hoffmann et al, 2007;Seidel and Mackel, 2007;de Moor and Verstraeten, 2008;Verstraeten et al, 2009b;Förster and Wunderlich, 2009;Notebaert et al, 2009;Fuchs et al, 2011;Stolz, 2011). Among these studies chosen budget elements vary and may range from sole quantifications of total floodplain storage (e.g., Stolz, 2011), to more detailed studies including different sink types (e.g., Macaire et al, 2002;Houben, 2008) and complex time-differentiated sediment budgets(e.g., Trimble, 2009;Verstraeten et al, 2009b;Notebaert et al, 2011a;Notebaert et al, 2013). For most catchments, sediment budgets show the large influence of anthropogenic land use changes on the sediment cascade (e.g., Trimble, 1999;Verstraeten et al, 2009a).…”

L’apport des recherches géomorphologiques et micromorphologiques récentes à l’archéologie des paysages de la Plaine de Caen (Calvados, Basse-Normandie)

“…Parallèlement, les recherches sur les dynamiques géomorphologiques holocènes des bassins versants de plaines et de plateaux de l'Europe occidentale se sont multipliées au cours des dix dernières années. Elles s'appuient le sur la définition de bilans sédimentaires holocènes établis à partir de l'étude des produits de l'érosion stockés sur les versants et dans les plaines alluviales (Macaire et al, 2002 ;Houben et al, 2006 ;Hoffmann et al, 2007 ;De Moor et Verstraeten, 2008 ;Morin et al, 2011) et plus rarement sur la prise en compte des pertes en sols par l'étude des profils pédologiques (Houben, 2008 ;Verstraeten et al, 2009 ;Notebaert et al, 2011). Ce type d'étude propose le plus souvent un bilan général de l'érosion et la chronologie de l'érosion des sols est essentiellement appuyée sur la chronologie des remplissages de fond de vallée (Allée, 2003 ;Hoffmann et al, 2007 ;Morin et al, 2011).…”