Turbulence as the Main Driver of Resuspension in Oscillatory Flow Through Vegetation

A series of laboratory experiments was conducted using arrays of rigid cylinders in a sandy bed as a proxy for mangrove roots and benthos. Synchronous colocated measurements of velocity and suspended sediment concentration were recorded within the array to investigate the effect of array density on sediment resuspension under different wave conditions. The measured increase in turbulent kinetic energy resulting from flow-vegetation interactions is directly linked to the observed increase in sediment resuspension. The observations emphasize the role of turbulent kinetic energy generated by the flow-vegetation interactions, rather than bed shear stress by the mean velocity, as the main driver of resuspension within the array. We test a modified Shields parameter analysis, as well as analytical predictions previously developed for unidirectional currents, which accurately predict resuspension thresholds under oscillatory flow conditions.