Large-Scale Channel Response to Erosion-Control Measures

C. Ylla Arbós*, A. Blom, S. R. White, R. Patzwahl, R. M.J. Schielen

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

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Abstract

Erosion-control measures in rivers aim to provide sufficient navigation width, reduce local erosion, or to protect neighboring communities from flooding. These measures are typically devised to solve a local problem. However, local channel modifications trigger a large-scale channel response in the form of migrating bed level and sediment sorting waves. Our objective is to investigate the large-scale channel response to such measures. We consider the lower Rhine River from Bonn (Germany) to Gorinchem (the Netherlands), where numerous erosion-control measures have been implemented since the 1980s. We analyze measured bed level data (1999–2020) around four erosion-control measures, comprising scour filling, bendway weirs, and two fixed beds. To get further insight on the physics behind the observed behavior, we set up an idealized one-dimensional numerical model. Finally, we study how the geometry and spacing of the measures affect channel response. We show that erosion-control measures reduce the sediment flux due to (a) lack of erosion over the measure and (b) sediment trapping upstream of the measure, resulting in downstream-migrating incision waves that travel tens of kilometers at decadal timescales. When the measures are in close proximity, their downstream effects may be amplified. We conclude that, despite fulfilling erosion-control goals at the local scale, erosion-control measures may worsen large-scale channel-bed incision.

Original languageEnglish
Article numbere2023WR036603
Number of pages16
JournalWater Resources Research
Volume60
Issue number3
DOIs
Publication statusPublished - 2024

Keywords

  • channel bed incision
  • channel response
  • engineered rivers
  • erosion-control measures
  • fixed beds

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