Riverine litter input is estimated to be a major contributor to marine litter, but there is no comprehensive information about the amount of litter being transported through rivers to the sea. Furthermore, there are no harmonised methodologies for providing quantitative data for comparable assessments of riverine litter.
This technical report compiles the options for monitoring riverine litter and quantifying litter fluxes, focusing on anthropogenic litter. It includes the current scientific and technical background regarding litter in river systems, their flow regime and basic properties. The document aims to provide recommendations for monitoring approaches and methodologies. It also provides indications on the issues which need to be further developed in a collaborative approach.
An extensive literature review has been performed in order to identify the existing options for the monitoring of litter items in rivers. Different monitoring methods are used in two environmental compartments: river water bodies and riverbanks. For a river water body, the river water surface can be monitored by visual observation and image acquisition, while collection methodologies for the water column include the use of retaining structures and sampling using grids, nets and filtration systems (with different mesh sizes and openings) at different water depths. Riverbank monitoring comprises the observation and eventual collection of litter items and sediment samples from the riverbanks. Methodologies are described and technical details are reported whenever available.