In the past, microplastic (MP) research has mainly focused on marine systems. The land-based discharges of MP into the oceans have been poorly studied so far, although they are assumed to represent an important contribution to the marine MP pollution. The significance of the various MP sources, sinks, pathways, and corresponding transport mechanisms has not been systematically assessed to date. Due to the methodological challenges, MP analysis will continue to provide mainly point information in the foreseeable future. To quantify the various MP sources, pathways and fates within and across ecosystems, data-driven models present crucial tools to connect field work results, scale up transport and movement processes to a landscape level, and simulate effects of mitigation measures. This session will give an insight into several spatial and temporal MP modelling approaches covering three exemplary river catchments in Germany that, as a whole, provide a framework to improve our systems understanding of the sources, pathways and fates of MP in the environment. Scope, boundaries, and mechanisms of the models, state of model development, first results, as well as data deficiencies and missing links will be presented and discussed. The aim is to highlight how field work analysts and modelers can shape their collaboration in the future to streamline mutual information exchange and create synergies between the disciplines.