Migrating subaqueous dunes capture clay flocs

Communications Earth & Environment, vol. 5

Abstract

Abstract Recent research highlights the abundance of floccule (flocs) in rivers, formed by aggregation of clay particles with organic matter. These flocs affect the transport and the eventual fate of clay. Flocs exhibit distinct behaviour from the unflocculated sedimentary counterparts: they can deform and break, and have higher settling velocities, which may in turn cause flocs to deposit and possibly interact with the riverbed. Here, we conducted systematic experiments in a laboratory flume to identify the mechanisms by which flocs and bedforms interact. Flocs showed a saltating (bouncing) behaviour, and were incorporated in the sediment bed as single flocs, clusters, or strings, via deposition and burial in the lee of a dune. Dune geometry was negligibly impacted by the presence of flocs. In natural systems, the burial of flocculated clay particles can affect contaminant spreading, aquatic ecology, the interpretation of deposition patterns, and clay transport.

Authors 8

1. Sjoukje Irene de Lange corresponding

   Wageningen University & Research

   Affiliation as printed

   Hydrology and Environmental Hydraulics Group, Department of Environmental Sciences, Wageningen University & Research, Wageningen, The Netherlands

2. Anne van der Wilk

   Wageningen University & Research

   Affiliation as printed

   Hydrology and Environmental Hydraulics Group, Department of Environmental Sciences, Wageningen University & Research, Wageningen, The Netherlands

3. Claire Chassagne

   Delft University of Technology

   Affiliation as printed

   Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft, The Netherlands

4. Waqas Ali

   Delft University of Technology

   Affiliation as printed

   Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft, The Netherlands

5. Maximilian P. Born Aachen Institute of Hydraulic Engineering and Water Resources Management

   RWTH Aachen University

   Affiliation as printed

   Institute of Hydraulic Engineering and Water Resources Management, RWTH-Aachen University, Aachen, Germany

6. Kristian Brodersen Aachen Institute of Hydraulic Engineering and Water Resources Management

   RWTH Aachen University

   Affiliation as printed

   Institute of Hydraulic Engineering and Water Resources Management, RWTH-Aachen University, Aachen, Germany

7. Antonius J. F. Hoitink

   Wageningen University & Research

   Affiliation as printed

   Hydrology and Environmental Hydraulics Group, Department of Environmental Sciences, Wageningen University & Research, Wageningen, The Netherlands

8. Kryss Waldschläger

   Wageningen University & Research

   Affiliation as printed

   Hydrology and Environmental Hydraulics Group, Department of Environmental Sciences, Wageningen University & Research, Wageningen, The Netherlands