Can vegetation root simulation in the laboratory lead to better understanding of flow-vegetation interactions?

Study of flow-vegetation interactions in river channels is necessary to comprehend its importance in sediment transport and morphological changes. Numerous laboratory experiments, numerical modelling, and field data have been collected and analyzed by researchers throughout decades. Previous laboratory experiments simulating vegetation majorly studied the impacts from vegetation shoot width and density. However, studies showed that along with the shape and size of vegetation, root-soil binding capacity also plays an important role in the morphological changes in the channel. To test this theory, we conducted experiments using a flume of 15 m in length and 1.8 m in width at the University of British Columbia. The main channel and floodplain width considered is 60 cm each. Two sets of experiments with and without vegetation roots in the floodplains were conducted. 3D printer was used to model the floodplain vegetation (see Figure). In the case of vegetation with roots, we considered it as a taproot system with a spiral structure attached to the simple root-shoot system as seen in the figure. Preliminary tests showed vegetation with roots was able to sustain the force of flow in different discharges in a better way without getting uprooted compared to vegetation without roots. Furthermore, there is also a difference in the morphology of the channels between the with and without roots experiments. The initial study showed that incorporating vegetation roots in the laboratory provides a more effective means of understanding flow-vegetation interactions and channel evolution. Furthermore, this study will also be helpful for the advancement of nature-based solutions like soil bioengineering techniques.

                           Simple root-shoot system                                                                               Taproot-shoot system