Same but Different: Riverbank Macroplastic Monitoring Framework

The riverbank macroplastic monitoring framework developed by Vriend, Roebroek, and van Emmerik
provides a structured way to design and compare riverbank plastic litter monitoring strategies.
It responds to the rapid growth of riverine plastic studies and the wide variation in existing protocols,
which makes it difficult to compare data, understand sources and sinks, and evaluate plastic pollution
mitigation measures across sites and programs.

Published as open access in Frontiers in Water (Environmental Water Quality, 2020),
the paper distills four core elements common to riverbank macroplastic monitoring methods:
space (scale, sampling area, and structure),
time (duration, timing, and frequency),
observers (professional staff, NGOs, citizen scientists), and
plastic categorization (item categories and size classes).
By explicitly structuring protocols around these elements, the framework enables scientists,
practitioners, and agencies to tailor monitoring strategies to their research questions and
resource constraints while maintaining transparency and comparability.

Scope of the riverbank macroplastic monitoring framework

This framework focuses on macroplastic litter deposited on riverbanks, rather than
floating plastics, water-column microplastics, or sediments. It draws on existing protocols such as
Plastic Pirates, Schone Rivieren (“Clean Rivers”), Battulga et al., and CrowdWater, as well as
established marine beach-litter methods (e.g., OSPAR, NOAA), to map similarities and differences in
how riverbank plastic monitoring is currently conducted. The framework is designed to:

• Support the design of new riverbank macroplastic monitoring protocols.
• Allow users to compare and harmonize existing monitoring programs.
• Link monitoring choices (where, when, how, and by whom) to specific research and policy questions.
• Clarify trade-offs between data detail, spatial and temporal coverage, and available resources.

Strengths

• Harmonization and comparability: provides a common language (space, time, observers, plastic categories)
  to describe riverbank protocols, improving cross-study comparability and enabling meta-analyses.
• Flexibility: the framework is not tied to one “correct” method, but can be applied to citizen science,
  NGO campaigns, or professional monitoring with different resource levels.
• Decision support: helps users select monitoring strategies that match four typical goals:
  understanding sources and sinks, quantifying loads, evaluating interventions, and long-term trend analysis.
• Policy relevance: more consistent riverbank macroplastic data can inform local and regional
  plastic pollution mitigation strategies and track effectiveness of implemented measures.

Limitations and considerations

• Not a single step-by-step protocol: the framework defines structure and design choices, but implementers
  must still choose specific methods (e.g., transect dimensions, item lists, survey frequency).
• Riverbank-only focus: it does not directly address floating plastics, microplastics, or plastics in biota
  and sediments, so it should be used alongside complementary monitoring approaches where a full riverine plastic budget
  is needed.
• Comparability depends on documentation: protocols must clearly report how space, time, observers, and
  plastic categorization were defined; otherwise, the benefits of the framework are reduced.
• Resource commitment: robust trend detection and evaluation of interventions still require
  long-term, repeated surveys and stable implementation over time.

Access and citation: the article is fully open access and can be read and downloaded from
Frontiers in Water:

Vriend, P., Roebroek, C. T. J., & van Emmerik, T. (2020).
Same but Different: A Framework to Design and Compare Riverbank Plastic Monitoring Strategies.
Frontiers in Water, 2, 563791. DOI:

https://doi.org/10.3389/frwa.2020.563791
Read the full article on Frontiers in Water