A Numerical Tool for Non-Buoyant Plastic Debris Short-Term Fate Prediction in the Nearshore Zone

The amount of plastic in the oceans is growing annually at dramatic rates. Knowing both how this pollutant spreads in water and its fate represents an important aspect of environmental protection. The currently available numerical models allow for the evaluation of plastic transport in the open sea. As part of the present study, a numerical model able to predict the transport not only of sediments but also of plastic debris in the nearshore zone has been implemented. In particular, the research activity described here focuses on implementing a module dedicated to simulating non-buoyant micro-plastic debris (TRANMPD) transport within a hydro-morphodynamic (HM) numerical model. The developed module integrates the results of numerous experimental studies conducted on plastics. The capability of the model TRANMPD-HM was evaluated through a comparative analysis with two-dimensional experimental tests. In general, it is observed that the model reproduces the processes offshore of the breaking zone quite well. In the area near the shoreline, the results are conditioned by the limits of the mor-phodynamic module which overestimates the effective transport.