Modelling flow-induced reconfiguration of variable rigidity aquatic vegetation

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 parameterisation 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.