Evolution and deposition patterns of turbidity currents under complex vegetation canopies

[Display omitted] •General spatiotemporal evolution law of turbidity currents under different vegetation canopy morphologies was verified.•Leaf morphology is a key attribute influencing vegetation resistance for turbidity currents.•Correlation between turbidity momentum and suspended sediment transport decreases under complex conditions. Understanding the flow-vegetation-sediment feedback mechanism is critical for ecological restoration of gently sloped landscapes. Numerous simulation or laboratory experiments on turbidity currents over vegetation have revealed the important roles of vegetation canopy morphology and structure in this feedback mechanism. However, there is still a lack of analysis on the related physical processes. This study investigated the evolutionary characteristics and sediment transport and deposition patterns of turbidity currents with different sediment size distribution in vegetation patches of different canopy morphologies through lock-exchange experiments. The roles of vegetation leaf morphology and canopy structure were explored by varying the leaf morphology and vegetation density with turbidity currents prepared using sediment samples configured with different particle sizes, which are more compatible with natural conditions. The kinetic characteristics and sediment distribution of the turbidity currents over vegetation were simultaneously analyzed, providing a new perspective for updating the methodology in laboratory experiments. The major findings of this study can be summarized as follows: 1) the general spatiotemporal evolution law of turbidity currents is applicable to complex vegetation canopy morphology; 2) canopy structure dominated by leaf morphology is an important influencing factor that needs to be taken into account in the research on vegetation resistance; and 3) the correlation between turbidity current momentum and suspended sediment transport decreases under complex conditions, and coarse-grained suspended sediment tend to limit the movement of turbidity currents and major deposition distance of the sediment. These findings can provide theoretical support for conservation of floodplain soil and water and restoration of watershed ecology.