Mechanics of Plastic Transport

Contact: James Lofty, Daniel Rebai

Research statement:

Our research investigates the mechanics of macro- and micro-plastics at the particle scale. This includes characterising bed, suspended, and surface load transport of litter, as well as parameterising key variables such as settling and rising velocities. We achieve this using large-scale hydrodynamic flumes and settling tanks, equipped with multiple high-speed cameras capable measuring the three-dimensional motion of plastic litter. The ultimate goal of this experimental research is to provide closure models for plastic transport to be implemented in hydrodynamics solver (depth- and section-averaged flow equations). These models will be able to simulate plastic movement, enabling the identification of accumulation zones, quantification of riverine plastic fluxes, and the design of effective monitoring and mitigation strategies.

Publications:

Lofty, J., Rebai, D., Valero, D., & Franca, M. J. (2026). The shapes and sizes of macroplastics and other litter in rivers. Environmental Science & Technology, 60(9), 7370–7379. https://doi.org/10.1021/acs.est.5c13126

Lofty, J., Hapich, H., Gray, A., Seidel, F., Maurer, B., Yang, Z., and Franca, M.J. (2026). Three-Dimensional Settling Dynamics of Environmental Microplastics. Environmental Science & Technology, 60(2), 2112–2121. https://doi.org/10.1021/acs.est.5c12960

Lofty, J., Valero, D., Moreno-Rodenas, A., Belay, B. S., Wilson, C., Ouro, P., & Franca, M. J. (2024). On the vertical structure of non-buoyant plastics in turbulent transport. Water Research, 254, 121306. https://doi.org/10.1016/j.watres.2024.121306

Lofty, J, Valero, D, Wilson, C, Franca, M. J, and Ouro, P. "Microplastic and natural sediment in bed load saltation: material does not dictate the fate." Water Research 243(2023): 120329: https://doi.org/10.1016/j.watres.2023.120329

Valero, Daniel, Biruk S. Belay, Antonio Moreno-Rodenas, Matthias Kramer, and Mário J. Franca. "The key role of surface tension in the transport and quantification of plastic pollution in rivers." Water Research 226 (2022): 119078: https://doi.org/10.1016/j.watres.2022.119078

Dataset:

The Shapes and Sizes of Macroplastics and Other Litter in Rivers https://doi.org/10.5281/zenodo.18670769

Settling velocities of environmental microplastics https://doi.org/10.5281/zenodo.17119737

Saltation dynamic of microplastics https://doi.org/10.5281/zenodo.7763722

Suspension dynamics of macroplastics: https://doi.org/10.5281/zenodo.8321370

Outreach and events:

RIRO University of Excellence Project Transfers:
https://www.kit.edu/kit/english/education-and-research-going-hand-in-hand.php

Webinar on Plastic pollution transport in rivers organised by IAHR Spain YPN:
https://www.youtube.com/watch?v=iF87JjN4wd4&list=PLSlAoS8gdfvplh4VIBVIXHM0sZbeIp-O5&index=17

Podcast interview:
https://www.deutschlandfunk.de/fluesse-plastikmuellbelastung-wurde-bislang-massiv-unterschaetzt-dlf-ea6c4820-100.html

River Flow 2026 Master Class: Plastic Transport in Rivers

Mário J. Franca, Andrew Gray, Dr. James Lofty

River Flow 2026 Special Session: Plastic pollution in rivers: Experiments, numerical simulation and field monitoring

James Lofty, Łukasz Przyborowski, Daniel Rebai, Arianna Varrani

Collaborations:

• Imperial College London (UK)
• University of California, Riverside (US)
• Cardiff University (UK)
• University of Manchester (UK)