Modulation of outer bank erosion by slump blocks: Disentangling the protective and destructive role of failed material on the three-dimensional flow structure

Christopher Hackney, Jim Best, Julian Leyland, Stephen E. Darby, Daniel Parsons, Rolf Aalto, Andrew Nicholas

Research output: Contribution to journalArticlepeer-review

Abstract

The three-dimensional flow field near the banks of alluvial channels is the primary factor controlling rates of bank erosion. Although submerged slump blocks and associated large-scale bank roughness elements have both previously been proposed to divert flow away from the bank, direct observations of the interaction between eroded bank material and the 3-D flow field are lacking. Here we use observations from multibeam echo sounding, terrestrial laser scanning, and acoustic Doppler current profiling to quantify, for the first time, the influence of submerged slump blocks on the near-bank flow field. In contrast to previous research emphasizing their influence on flow diversion away from the bank, we show that slump blocks may also deflect flow onto the bank, thereby increasing local shear stresses and rates of erosion. We use our measurements to propose a conceptual model for how submerged slump blocks interact with the flow field to modulate bank erosion.

Original languageEnglish (US)
Pages (from-to)10663-10670
Number of pages8
JournalGeophysical Research Letters
Volume42
Issue number24
DOIs
StatePublished - Dec 28 2015

Keywords

  • bank erosion
  • bank roughness
  • near-bank flow field
  • slump blocks

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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