Large samples of catchments can provide insights into hydrological processes that cannot be obtained from small samples. This session aims 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. Landscape characterisation - hydrological processes are shaped by the interplay of landscape attributes such as topography, climate, vegetation, soil, geology: how to better understand this interplay using available data sets?
2. Generalisation from the catchment to continental scale: 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, including across borders
4. Quantification and synthesis of data quality and uncertainty, including across borders
5. Identification and characterisation of dominant hydrological processes with limited data: how far can we get using hydrological signatures?
6. Human intervention and land cover changes: how to characterise and account for these processes in large-sample studies?
7. 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. Our invited speaker for 2019 is Vazken Andreassian.

In addition to this session, we will organise a splinter meeting to discuss and coordinate the production of large-sample data sets. Following a similar meeting at EGU 2018, it will be entitled “Large sample hydrology: facilitating the production and exchange of data sets worldwide”, its location and date will be indicated in the final programme.

The session and the splinter meeting will be organised in the framework of the Panta Rhei Working Group on large-sample hydrology.