Plastics in the river environment are of major concern due to their potential pathways into the ocean, their persistence in the environment, and their impacts on human and marine health. It has been documented that plastic concentrations in riparian environments are higher following major rain events, where plastic can be moved through surface runoff. Considering the hazard that plastic waste poses to the environment, monitoring techniques are needed to aid in locating, monitoring, and remediating plastic waste within these systems. Dams are known to trap sediments and pollutants, such as metals and Polychlorinated Biphenyls (PCBs). While there is an established background on the monitoring of dams using the synoptic coverage provided by satellite imaging to observe water quality and volume, the detection of marine debris in riparian systems remains challenging, especially in cloudy conditions. Herein, we exploit the use of Synthetic Aperture Radar (SAR) to understand its capabilities for monitoring marine debris. This research focuses on detecting plastic islands within the Drina River system in Bosnia and Herzegovina and Serbia. Here, the results show that the monitoring of these plastic accumulations is feasible using Sentinel-1 SAR data. A quantitative analysis of detection performance is presented using traditional and state-of-the-art change detectors. The analysis of these detectors indicates that detectors that can utilise the coherent data from Single Look Complex (SLC) acquisitions are perform better when compared with those that only utilise incoherent data from Ground Range-Detected (GRD) acquisitions, with true positive detection ratings of ~95% with 0.1% false alarm rates seen in the best-performing detector. We also found that that the cross-pol VH channel provides better detection than those based on single-pol VV polarisation.

No abstract

No abstract

In recent years, marine plastic pollution has seen increased coverage in the public interest and research due to a greater understanding of the scale and impact of plastic pollution within the marine environment. Considering the hazard that plastic waste poses on the environment, marine life, and on humans, remote-sensing techniques could provide timely information on their detection and dynamics. The remote sensing of marine plastic is a relatively new field and research into the capabilities of radar for detecting and monitoring marine plastic pollution is generally limited, with several interactions and mechanisms being largely unknown. Here, we exploit the use of a C- and X-band radar to understand the capabilities of monitoring marine plastics. Our results show that backscattering differences in the C- and X-band between the reference water (called here as “clean”) and the test water filled with plastic can be detected in some conditions (based on statistical analysis). Overall, the results indicate that the X-band frequency performs significantly better than the C-band frequency, with X-band detecting significant differences in backscattering in 48/68 test cases compared with C-band detecting differences in 20/67 test cases. We also find that the difference in backscattering is dependent on the size and shape of the plastic object, as well as the wave conditions which the plastic is moving on. This study provides new insights on the radar capabilities for detecting marine plastic litter and new information which can be used in the planning of future missions and studies on the remote sensing of marine plastic pollution.

No abstract