Classifying Foliated Ecohydraulics via Three-Dimensional Modelling

In rivers, marshes, and mangroves, dense vegetation is a ubiquitous, but complex, obstruction to flow, demanding special consideration of its effect on hydromorphological processes. The last twenty-five years have seen a range of studies on different aspects of flow-vegetation interaction, but to properly understand the impact of foliated, heterogeneous, and branching plants, it is necessary to adopt three-dimensional structural modelling techniques to quantify their hydrodynamic interactions. We apply the recently developed Elastically Articulated Body Method (EABM), which describes the three-dimensional dynamics of complex plant morphologies to investigate the flow-induced reconfiguration of leafy plants (such as Ceratophyllum, Suaeda, and Spartina). Our results show that the dynamics and hydraulic effects of different plant species, for instance those that can be used as nature-based solutions for coastal protection, can be classified using a new dimensionless parameter “Isoanemeity”. This parameter is a descriptor of the ability of leaves to flexibly streamline, compared to that of the whole plant, and as such predicts the predominant mechanism of plant reconfiguration, and the role of foliage in creating drag. This classification can benefit those modelling drag and turbulence in large hydrological systems with a variety of species of vegetation.