Large and diverse samples of catchments can provide generalisable insights that improve the understanding of hydrological processes beyond findings from single catchments. This session provides the opportunity to showcase recent data- and model-based efforts on large-sample hydrology, which advance the characterisation, understanding and modelling of hydrological diversity. We welcome abstracts from a wide range of fields, including catchment hydrology, land-surface modelling, eco-hydrology, groundwater hydrology and hydrometeorology, which seek to explore:

1. Identification and characterisation of dominant hydrological processes: what is the importance and interplay of landscape attributes for hydrological processes and signatures? How can this interplay be characterised with limited data?
2. Generalisation across spatial scales: how can we use large samples of catchments to refine process understanding and modelling at the regional to global scale?
3. Hydrological similarity and catchment classification: how can information be transferred between catchments?
4. Development of new large-sample data sets, as well as quantification and synthesis of data quality and uncertainty in existing data
5. Human intervention, climate change, and land cover changes: how can these processes be accounted for in large-sample studies?
6. Revisiting hypotheses testing: testing the generality of existing hypotheses (particularly those originally formulated on small samples of catchments) using large samples

We encourage abstracts addressing any of these challenges, in particular those aiming at reducing geographical gaps (i.e., contributing to a more balanced spatial distribution of large-sample data sets) and making use of global data sources (e.g., remote-sensed data or re-analyses) to facilitate comparison between catchments from different parts of the globe.

In addition to this session, there will be a splinter meeting to discuss and coordinate the production of large-sample data sets. Following a similar meeting at EGU 2018 and 2019, it will be entitled “Large sample hydrology: facilitating the production and exchange of data sets worldwide” - see the final programme for location and timing.

The session and the splinter meeting are organised as part of the Panta Rhei Working Group on large-sample hydrology.