Observations of coastal sediment erosion using in-line holography

This paper demonstrates how in-line particle field holography may be used to study erosion processes in coastal sediments, in particular to visualize the morphologies of eroded sediment particles and to investigate how organic matter affects the floc size and erosion threshold in incipient sediment erosion. In-line holography produces 3D images and provides higher resolution over larger recording volume compared with other imaging techniques.
The study examines the dependence of the observed shearing stress, particle size distributions and morphologies of particles on the duration of desiccation of the sediment bed, and on the concentration of extra-cellular polymeric substance. Both artificial sediment (produced from cleaned sediments by the addition of natural extra-cellular polymeric substance) and intact sediment were used. The required hydrodynamic shear stress to produce erosion on the sediment beds was generated using a cohesive strength meter (CSM). Characterization of the eroded particle properties was carried out using 2D image analysis.