Abstract
AbstractLow‐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. Copyright © 2016 John Wiley & Sons, Ltd.
Highlights
Predicting stream morphodynamics is a key aspect in stream restoration projects, in order to prevent flooding or unwanted bank erosion, and to plan and minimize management (Eekhout et al, 2015)
The conceptual model of oblique aggradation presented here is based on data from the Drentsche Aa, we expect it to be applicable to the morphological development of other streams in similar settings
We identify oblique aggradation as a key process leading to highly sinuous planforms in peat-filled valley systems
Summary
Predicting stream morphodynamics is a key aspect in stream restoration projects, in order to prevent flooding or unwanted bank erosion, and to plan and minimize management (Eekhout et al, 2015). A knowledge gap exists between stream restoration demands and current understanding on the morphodynamic functioning of low-energy streams (Wohl et al, 2005; Walter and Merritts, 2008; Lespez et al, 2015). In many stream restoration projects in lowlands, single-thread, sinuous streams are often seen as ‘natural’ and used as a reference Sometimes this reference is derived from historical maps (Kondolf, 2006). Some studies found evidence that the sinuous planform of low-energy streams may be the consequence of historical land-use changes that started around the Bronze Age (Broothaerts et al, 2014; Lespez et al, 2015) or later (Kondolf et al, 2002), or may be the result of historical water engineering (e.g. for watermills) (Walter and Merritts, 2008). The discipline has made considerable progress in developing relevant knowledge and tools for water managers (Brierley and Fryirs, 2000; Kondolf et al, 2003b)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
