Modelling flow-induced reconfiguration of variable rigidity aquatic vegetation

ABSTRACT

Aquatic vegetation is an important component of coastal and riverine environments and plays a significant role in shaping their evolution. The extent and nature of eco-hydraulic interaction depends upon the geometric and biophysical properties of the vegetation which affect the drag force and vegetation reconfiguration. Such vegetation properties commonly vary along each stem. However, this variability has not received significant attention in previous models. Here, we present a biomechanical model, based upon local parameterization of stem properties which can represent variable rigidity stems. The model is validated for straight and curved beams before being applied to experimental data using surrogates with variable thickness and Young’s modulus. Finally, the model is applied to saltmarsh vegetation data. The results for saltmarsh vegetation show that using stem-averaged properties may result in errors in predicted drag force of up to 26% and highlights the need to consider the reconfiguration of variable rigidity stems.

Keywords:

• Bending stiffness
• biomechanics
• flexural rigidity
• flow-biota interactions
• surrogate vegetation
• vegetated flows

Acknowledgements

We thank Prof. Stephen Rice from the School of Geography and Environment, Loughborough University for providing access to the flume facilities and Prof. Qingping Zou for providing data for model validation. Data and code relating to this paper are available on the Loughborough University Data Repository (DOI:10.17028/rd.lboro.12077814). We would also like to thank the associate editor and three anonymous reviewers whose comments have improved the paper.

Additional information

Funding

MP acknowledges funding by the Deutsche Forschungsgemeinschaft [grant number: PA 2547/1-1], the Lower-Saxon Ministry of Research and Culture and Volkswagen Foundation [FKZ: 76251-17-5/19].