Abstract

Gravity currents frequently occur when excess suspended sediments are flushed along a river and discharged into greater natural water environments such as lakes, reservoirs, and estuaries. Gravity and turbidity currents have been broadly investigated, but the effect of aquatic vegetation on their propagation in natural waters still presents several open questions. We conducted a series of laboratory experiments to investigate how flexible vegetation affects the propagation and flow structure of gravity currents on a constant slope. We used both rigid cylinders and flexible synthetic plants to mimic natural submerged vegetation canopies. By varying density configurations of the vegetation array and comparing the outcomes of rigid cylinders and flexible plants, the data showed distinct patterns based on array density and plant morphology. A two-layer current was created when the array density is large enough to redirect the flow, as opposed to sparser conditions where the denser fluid passes swiftly through the array. Flexible vegetation further suppresses the propagation speed of gravity currents compared to arrays of rigid cylinder with the same density, highlighting the importance of the multi-scale processes driven by complex plant morphologies that are not represented by rigid cylinder arrays.