UAV monitoring for assessing beach litter pollution and coastal morphodynamics: case studies from the Molise region (central Adriatic coast, Italy)

Beach litter (BL) poses a significant threat to coastal ecosystems and marine biodiversity. Monitoring its density, composition, and distribution is crucial to develop effective management strategies and support the sustainable use of the beach environments. Traditional in situ visual surveys allow detailed identification and classification of BL items but are often limited in spatial coverage and require significant time investment. Recent advancements, including the use of Unmanned Aerial Vehicles (UAV), have enabled more efficient assessments of coastal litter and related geomorphological features.

This study investigates the characteristics and distribution of BL and its relationship with coastal morphodynamics along two unmanaged beaches located along the Molise coast (southern Italy): Petacciato and Ramitelli beaches. These sites were selected based on their distinct morphodynamic characteristics, and their free beach status.

The monitoring methodology considered international guidelines [1, 2]. UAV surveys were conducted before and after a significant storm event to assess its impact not only on beach morphology but also on BL distribution. Flights were carried out with a Yuneec Typhoon H520 hexacopter using a flight height of 15 meters [2]. High-resolution orthophotos were analysed to manually identify BL larger than 2.5 cm and classify them according to the Joint List for Marine Macrolitter Monitoring [2]. Items were categorized by material type, size, and weight, and unusual objects were documented in detail. Shoreline and dune foot variations along with morphological changes of the beach were also quantified to evaluate the role of coastal processes in BL dispersion and accumulation patterns.

First results reveal significant differences in BL density and composition between the two study sites, but with plastic materials dominating both the collected items, consistent with broader Mediterranean trends [3]. The post-storm survey highlighted the role of weather events in redistributing litter, particularly at the southern limit of the Ramitelli beach which is in contact with the jetty of the Saccione River mouth that drives the accumulation of beach litter on the adjacent shoreline. This study underscores the importance of integrating UAV-based monitoring with geomorphological analyses to better understand the interplay between coastal dynamics and BL distribution. The monitoring of these relationships can provide essential data to support and improve coastal management and design targeted beach clean-up strategies.

 

 

Key Words

Remote Sensing, Coastal monitoring, Coastal geomorphology, UAV images, Visual assessment, Litter beach analysis.

 

[1] Vlachogianni T. (2017) - Methodology for Monitoring Marine Litter on Beaches. Macro-Debris (> 2.5 cm). DeFishGear, 1-16.

[2] Fleet D., Vlachogianni T. & Hanke G. [Eds] (2021) - A joint list of litter categories for marine macrolitter monitoring. JRC Technical Reports, Publications Office of the European Union, Luxembourg, 30348, 52.

[3] Rizzo A., Sozio A., Anfuso G., La Salandra M., Sasso C. (2022) – The use of UAV images to assess preliminary relationships between spatial litter distribution and beach morphodynamic trends: the case study of Torre Guaceto beach (Apulia Region, Southern Italy). Geogr. Fis. Dinam. Quat. 45 (2022). 237-250.