Reference : Comparison of methods for quantifying active layer dynamics and bedload discharge in ...
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Earth sciences & physical geography
http://hdl.handle.net/2268/132904
Comparison of methods for quantifying active layer dynamics and bedload discharge in armoured gravel-bed rivers
English
Houbrechts, Geoffrey mailto [Université de Liège - ULg > Département de géographie > Département de géographie >]
Van Campenhout, Jean mailto [Université de Liège - ULg > Département de géographie > Hydrographie et géomorphologie fluviatile >]
Levecq, Yannick mailto [Université de Liège - ULg > Département de géographie > Hydrographie et géomorphologie fluviatile >]
Hallot, Eric mailto [Université de Liège - ULg > Département de géographie > Hydrographie et géomorphologie fluviatile >]
Peeters, Alexandre mailto [Université de Liège - ULg > Département de géographie > Hydrographie et géomorphologie fluviatile >]
Petit, François mailto [Université de Liège - ULg > Département de géographie > Hydrographie et géomorphologie fluviatile >]
2012
Earth Surface Processes & Landforms
John Wiley & Sons, Inc
37
1501-1517
Yes (verified by ORBi)
International
0197-9337
Chichester
United Kingdom
[en] active layer ; armour ; scour chains ; PIT-tag ; iron slag
[en] Several methods were employed in the Ardennian rivers (Belgium) to determine the depth of the active layer mobilized during floods and to evaluate the bedload discharge associated with these events. The use of scour chains has shown that the depth of the active layer is systematically less than the b-axis of the average particle size (D50) of the elements which compose the surface layer of the riffles. This indicates that only a partial transport exists during low magnitude floods. The bedload discharge has been evaluated by combining data obtained using the scour chains technique and the distance covered by tracers. Quantities of sediment transported during frequent floods are relatively low (0 02 t km–2) due to the armour layer which protects the subsurface material. These low values are also related to the fact that the distance calculated for mobilized bedload only applies to tracers fitted with PIT (passive integrated transponder)-tags (diameter>20 mm), whereas part of the bedload discharge is composed of sand and fine gravel transported over greater distances than the pebbles. The break-up of the armour layer was observed only once, for a decennial discharge. During this event, the bedload discharge increased considerably (2 t km–2). The use of sediment traps, data from dredging and a Helley–Smith sampler confirm the low bedload transport in Ardennian rivers in comparison to the bedload transport in other geomorphological contexts. This difference is explained by the presence of an armoured layer but also by the imbricated structures of flat bed elements which increase the resistance to the flow. Finally, the use of the old iron industry wastes allowed to quantify the thickness of the bed reworked over the past centuries. In the Lembrée River, the river-bed contains slag elements up to a depth of about 50 cm, indicating that exceptional floods may rework the bed to a considerable depth.
Researchers ; Professionals ; Students ; General public
http://hdl.handle.net/2268/132904
10.1002/esp.3258
Copyright © 2012 John Wiley & Sons, Ltd.

File(s) associated to this reference

Fulltext file(s):

FileCommentaryVersionSizeAccess
Restricted access
ESPL_2012_3258_Houbrechts_et_al.pdfPublisher postprint392.22 kBRequest copy

Bookmark and Share SFX Query

All documents in ORBi are protected by a user license.