Plastic Transport in Coastal Seas: Lagrangian Tracking of Microplastics in the Nearshore and Evaluation of Beaching.
In this work, the multi-layer non-hydrostatic free-surface model SWASH is used together with Lagrangian tracking software Parcels in order to predict the transport of weakly inertial particles in the nearshore. The top panel of Fig. 1 shows the modeling framework. We have successfully incorporated the capability to simulate inertial and buoyant particles and have validated this implementation with an analytical solution for the settling of particles under linear waves (3). The results are shown in the middle panels of Fig.1.
Flume-like (2DV) flow simulations allow us to study in detail the cross-shore vertical and horizontal processes that govern the motion of plastic (bottom panels Fig. 1). The full 3D simulations give us insight into the behaviour of plastic in flows where alongshore components are important. Current work focuses on how particles with different properties behave in breaking waves as well as the larger scale behaviour of particles in bar/rip systems.
This work will firstly contribute to the understanding of the behaviour of plastic particles in the coastal region. However, if we zoom out and consider the global problem of ocean plastic pollution, it provides a versatile modeling framework for the boundaries of the ocean. The modeling scale of this work addresses the gap between the global scale transport estimates on one hand, and local beach observations of plastic on the other hand (4,5).