14 Sep 2021

14 Sep 2021

Review status: this preprint is currently under review for the journal OS.

Using machine learning and beach cleanup data to explain litter quantities along the Dutch North Sea coast

Mikael L. A. Kaandorp1, Stefanie L. Ypma1, Marijke Boonstra2, Henk A. Dijkstra1, and Erik van Sebille1 Mikael L. A. Kaandorp et al.
  • 1Institute for Marine and Atmospheric Research Utrecht, Department of Physics, Utrecht University, Utrecht 3584 CS, Netherlands
  • 2Stichting De Noordzee, Arthur van Schendelstraat 600, 3511 MJ Utrecht, the Netherlands

Abstract. Coastlines potentially harbor a large part of litter entering the oceans such as plastic waste. The relative importance of the physical processes that influence the beaching of litter is still relatively unknown. Here, we investigate the beaching of litter by analyzing a data set of litter gathered along the Dutch North Sea coast during extensive beach cleanup efforts between the years 2014–2019. This data set is unique in the sense that data is gathered consistently over various years by many volunteers (a total of 14,000), on beaches which are quite similar in substrate (sandy). This makes the data set valuable to identify what environmental variables might play an important role in the beaching process, and to explore the variability of beach litter. We investigate this by fitting a random forest machine learning regression model to the observed litter concentrations. We find that especially tides play an important role, where an increasing tidal variability and tidal height lead to less litter found on beaches. Relatively straight and exposed coastlines appear to accumulate more litter. The regression model indicates that transport of litter through the marine environment is also important in explaining beach litter variability. By understanding what processes cause the accumulation of litter on the coast, recommendations can be given for more effective removal of litter from the marine environment. We estimate that 16,000–31,400 kilograms (95 % confidence interval) of litter are located on the 365 kilometers of Dutch North Sea coastline.

Mikael L. A. Kaandorp et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on os-2021-83', Anonymous Referee #1, 14 Oct 2021
  • RC2: 'Comment on os-2021-83', Anonymous Referee #2, 18 Oct 2021
  • RC3: 'Comment on os-2021-83', Anonymous Referee #3, 18 Nov 2021

Mikael L. A. Kaandorp et al.

Model code and software

Code to run the data analysis Mikael L. A. Kaandorp, E. van Sebille

Mikael L. A. Kaandorp et al.


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Short summary
A lot of the marine litter, such as plastics, is located on or around beaches. The total amount and the transport of this litter is not well understood. We investigate this by training a machine learning model with data of cleanup efforts on Dutch beaches between 2014–2019, obtained by about 14,000 volunteers. We find Dutch beaches to contain up to 30,000 kilograms of litter, largerly driven by tides, oceanic transport, and how exposed beaches are.