Aerial and underwater drones for marine litter monitoring in shallow coastal waters: factors influencing item detection and cost-efficiency

Abstract

Although marine litter monitoring has increased over the years, the pollution of coastal waters is still understudied and there is a need for spatial and temporal data. Aerial (UAV) and underwater (ROV) drones have demonstrated their potential as monitoring tools at coastal sites; however, suitable conditions for use and cost-efficiency of the methods still need attention. This study tested UAVs and ROVs for the monitoring of floating, submerged, and seafloor items using artificial plastic plates and assessed the influence of water conditions (water transparency, color, depth, bottom substrate), item characteristics (color and size), and method settings (flight/dive height) on detection accuracy. A cost-efficiency analysis suggests that both UAV and ROV methods lie within the same cost and efficiency category as current on-boat observation and scuba diving methods and shall be considered for further testing in real scenarios for official marine litter monitoring methods.

Designing Unmanned Aerial Survey Monitoring Program to Assess Floating Litter Contamination

“…Overcast conditions, high sun, waves, and floating items partially submerged in the water column can easily decrease image quality for object detection and potentially lead to the need of discarding a large portion of each image. The use of the multispectral sensors can reduce some of the negative impacts of poor conditions, as some channels generally produce outputs that are less sensitive to light backscatter over the sea surface (i.e., infrared, near-infrared) [36,77]. Thermal sensors can also be adequate to detect large objects that have a large proportion that is air-exposed [93]; however, they are typically unable to detect objects that are frequently submerged and cooled by waves and sea spray.…”

“…Operation flexibility and simplicity make UASs promising platforms for developing remote sensing protocols and monitoring litter using systematic approaches. There have been a growing number of studies focusing on the use of UAS-based remote sensing and AI to monitor litter pollution; however, most of them have focused on beached litter [51,54,65,67,70,[72][73][74][75], and only a few have explored their use for floating litter [38,46,73,76,77]. A recent critical review on beached litter survey studies using UAS remote sensing [65] summarizes the findings of recent studies and outlines basic guidelines for developing and implementing monitoring programs.…”

Mapping of marine litter on the seafloor using WASSP S3 multibeam echo sounder and Chasing M2 ROV

“…If it is necessary to detect smaller forms of marine debris on the seafloor, the MBES acquisition frequency must be higher, the number of acoustic signals (ping rate) must be higher, and the bandwidth must be smaller. 4) Visual inspection and morphometric analysis of marine litter using ROV -in the detection of marine litter on the seafloor in shallow waters, the most used method is the diving method, which, although widely applicable and validated, can be timeconsuming, requires high costs, expertise, and the deployment of a larger team (Escobar-Sánchez et al, 2022). For this reason, ROV can be very useful, although it is important to be aware of the lack of application of ROV in visual inspection, which leads to a possible underestimation of the amount of litter on the seafloor since buried elements of marine waste cannot be detected.…”

Drone for a Cleaner Coast: Monitoring and Analysis of Marine Debris at Sindulang Beach

“…Penggunaan survei udara dengan UAV (Adade et al, 2021)merupakan alternatif yang sangat baik dalam kegiatan pemantauan, karena mampu menghasilkan data citra dengan resolusi tinggi (Bao et al, 2018;Escobar-Sánchez et al, 2022). Penggunaan UAV dapat memberikan data aktual dengan resolusi tinggi untuk menyajikan hasil pemantauan sampah di Pantai Sindulang dengan tingkat akurasi yang tinggi.…”