Oblique aggradation: explanation for the sinuosity of streams in peat-filled valleys

Overview for practitioners

We propose a conceptual model to explain the origin of stream bends in peat-filled valleys to better inform stream restoration.

Innovation to practice
Restoration projects often aim to recover the natural stream shape. The origin of streams that flow through peat-filled deposits is interesting due to their limited erosion and bank migration over time.

We chose the Drentsche Aa, a stream in the Netherlands that has very high sinuosity and flows through a peat filled-valley. The stream naturally developed very tight and relatively fixed bends that changed little over time. Data collected with various methods was used to map the stream profile back when the peat growth started 12.000 years ago (see a visual overview in the storyline for practitioners):

  • Data from Makaske et al (2015) about the date and rate of peat development;
  • Ground-Penetrating Radar to distinguish sandy channel deposits within the peat;
  • Optically stimulated luminescence dating to determine the deposition period of sand layers.

Findings and implications to policy
We found that the bends in the Drentsche Aa depend on the relative position of the channel to the erodible sandy side or less erodible peaty side. The figure below shows the schematic representation what we called in our publication “oblique aggradation”. Similar studies should be carried out in The Netherlands and around the world to verify the range of stream valley slopes and peat growth rate in which this aggradation type can occur.

Schematic representation of the oblique aggradation. (Source: Candel et al. 2017)

Related outputs

  • Journal publication
    Candel, J. H. J., Makaske, B., Storms, J. E. A., & Wallinga, J. (2017). Oblique aggradation: a novel explanation for sinuosity of low-energy streams in peat-filled valley systems. Earth Surface Processes and Landforms, 42(15), 2679–2696. https://doi.org/10.1002/esp.4100.
  • Makaske, A., Maas, G. J., Grootjans, A., Meijles, E., Everts, H., & Vries, N. de. (2015). Veen verschijnt en verdwijnt : Grondwaterstromen en veenvorming. In T. Spek, H. Elerie, J. P. Bakker, & I. Noordhoff (Eds.), Landschapsbiografie van de Drentsche Aa (pp. 54–81). Assen: Koninklijke Van Gorcum.

Related dataset
Dataset contains: (1) GPR data from Drentsche Aa at the locations Amen, Loon, Gasteren2 and Schipborg. (2) Coring data and LLG software (©Utrecht University) to open coring data. (3) Radiocarbon (14C) data. and (4) Optically stimulated luminescence (OSL) dating results. Dateset is temporary stored in DataVerse https://dataverse.nl/dataset.xhtml?persistentId=hdl:10411/J3W4IS

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Related storylines for practitioners

How do bends form in peat-land streams?

Jasper Candel

We propose a conceptual model to explain the origin of bends in peatland streams to better inform stream restoration.

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Last modified: 17/09/2018


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Jasper Candel

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