The role of biophysical cohesion on subaqueous bed form size
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Biologically active, fine-grained sediment forms abundant sedimentary deposits on Earth's surface, and mixed mud-sand dominates many coasts, deltas, and estuaries. Our predictions of sediment transport and bed roughness in these environments presently rely on empirically based bed form predictors that are based exclusively on biologically inactive cohesionless silt, sand, and gravel. This approach underpins many paleoenvironmental reconstructions of sedimentary successions, which rely on analysis of cross-stratification and bounding surfaces produced by migrating bed forms. Here we present controlled laboratory experiments that identify and quantify the influence of physical and biological cohesion on equilibrium bed form morphology. The results show the profound influence of biological cohesion on bed form size and identify how cohesive bonding mechanisms in different sediment mixtures govern the relationships. The findings highlight that existing bed form predictors require reformulation for combined biophysical cohesive effects in order to improve morphodynamic model predictions and to enhance the interpretations of these environments in the geological record.
Parsons , D R , Schindler , R J , Hope , J A , Malarkey , J , Baas , J H , Peakall , J , Manning , A J , Ye , L , Simmons , S , Paterson , D M , Aspden , R J , Bass , S J , Davies , A G , Lichtman , I D & Thorne , P D 2016 , ' The role of biophysical cohesion on subaqueous bed form size ' Geophysical Research Letters , vol Early View , pp. 1-8 . DOI: 10.1002/2016GL067667
Geophysical Research Letters
©2016. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
This work was supported by the UK Natural Environment Research Council under grant NE/I027223/1 (COHBED). D.M.P. acknowledges the support of the Marine Alliance for Science and Technology for Scotland (MASTS) pooling initiative in the completion of this study. MASTS is funded by the Scottish Funding Council (grant reference HR09011) and contributing institutions.
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