Marine Litter Drift Monitoring (Forecast and Hindcast) in the Channel and the North Atlantic

Abstract

<p>Meteorological events, such as storms and/or gale force winds, act as triggers to influx of macro litter into the hydrological cycle via run off from land into rivers. These rivers discharge into the sea and the marine litter is then transported through the region by currents and wind either becoming entrained in the sea, possibly sinking and/or disintegrating into micro marine litter or ending up being stranded at the coast then washed back ashore or flown on to the land. Thanks to a Copernicus Marine Environment Monitoring Service (CMEMS) grant, ARGANS Ltd has developed a web-based service, called Litter-TEP, that aims to track marine litter from the source. It uses a parametric model of riverine macro litter discharge, to seed drift models of the NE Atlantic Shelf Region (OSPAR II/III), providing to end-users a 5-day running forecast of macro-litter density in the sea, potential beach stranding at the coast and, inversely, where a beach litter event is identified to provide the likelihood of where the litter entered the sea. In order to determine drift trajectories, we use ocean current, wave and wind forecasts from Copernicus Marine Service high quality analysis and forecast products for the European North West Shelf seas. The main issues which have been identified, and for which we perform additional R&D, are the following: a) source’s modelling and estimation of volume of litter introduced to the sea, b) litter’s types for which the drift model should be adapted, and c) the spatial resolution of models in the littoral area (nearshore) vs. offshore. In fact, for the beaching & refloating models, we need of a bathymetry at the scale of 1/3000 and a coastal cartography at 1/1000 to obtain the beach profile, then calculate the runoff on the beach, the rip currents, etc. The next enhancement, driven by users’ requirements, is to improve the land discharge model vide collection of litter seeings with citizen crowdsourcing apps, and records of beach litter surveys, and beach cleaning campaigns. Another improvement, in the mid-term, targets the discharge models, using refined hydrologic schemes for the watersheds, and better estimates of habitats (rural, urban, industrial, …).  ARGANS Ltd service is the next-generation tool for planning beach cleaning and helping local authorities to track back the trash to their sources, leading the fight against litter pollution and for improvement of the river water quality. </p>