Oblique aggradation

Oblique aggradation: A novel explanation for sinuosity of low-energy streams in peat-filled valley systems

Candel, Jasper H J (Wageningen University & Research)
Makaske, Bart (Wageningen University & Research)
Storms, J.E.A. (TU Delft Applied Geology)
Wallinga, J. (Wageningen University & Research)

2017

Low-energy streams in peatlands often have a high sinuosity. However, it is unknown how this sinuous planform formed, since lateral migration of the channel is hindered by relatively erosion-resistant banks. We present a conceptual model of Holocene morphodynamic evolution of a stream in a peat-filled valley, based on a palaeohydrological reconstruction. Coring, ground-penetrating radar (GPR) data, and ¹⁴C and OSL dating were used for the reconstruction. We found that the stream planform is partly inherited from the Late-Glacial topography, reflecting stream morphology prior to peat growth in the valley. Most importantly, we show that aggrading streams in a peat-filled valley combine vertical aggradation with lateral displacement caused by attraction to the sandy valley sides, which are more erodible than the co-evally aggrading valley-fill. Owing to this oblique aggradation in combination with floodplain widening, the stream becomes stretched out as channel reaches may alternately aggrade along opposed valley sides, resulting in increased sinuosity over time. Hence, highly sinuous planforms can form in peat-filled valleys without the traditional morphodynamics of alluvial bed lateral migration. Improved understanding of the evolution of streams provides inspiration for stream restoration.

http://resolver.tudelft.nl/uuid:092c1e45-41df-4b11-8561-6b3e285d90f8

https://doi.org/10.1002/esp.4100

0197-9337

Earth Surface Processes and Landforms, 42 (15), 2679-2696

Institutional Repository

journal article

© 2017 Jasper H J Candel, Bart Makaske, J.E.A. Storms, J. Wallinga