Caravan-Qual: A global scale integration of water quality observations into a large-sample hydrology dataset

The last decade has seen a proliferation in efforts to compile, standardise and openly disseminate datasets spanning hundreds to thousands of catchments, driven by the emergence of large-sample hydrology as a sub-discipline in hydrological sciences. While these datasets have facilitated novel research into the field of water quantity (e.g. streamflow prediction), comparable advances for water quality research remain limited¹.

Here, we present the first global integration of water quality into large-sample hydrology (named Caravan-Qual). The dataset contains >70 million river water quality observations covering 100 water quality constituents, compiled from a range of national-to-global datasets covering the period of 1980-2025. Water quality data has been standardised to common naming conventions and reporting units, and further processed to remove duplicates, detect outliers and handle observations below detection limits. Leveraging the Caravan² dataset and open-source software, water quality monitoring stations are matched to streamflow gauges – with ~31% of daily water quality observations paired to a daily streamflow measurement within a 10km distance. Furthermore, meteorological variables (e.g. temperature, precipitation, net radiation) and catchment attributes (e.g. land cover, soil characteristics) are derived for water quality monitoring stations.

Caravan-Qual is openly available at: https://doi.org/10.5281/zenodo.17787066³, and is envisaged to facilitate research into topics including:

• Spatio-temporal analysis of river water quality dynamics at local to global scales.
• Investigation of the relationships between (constituent-specific) river water quality responses and hydrological, meteorological and catchment characteristics.
• The development and evaluation of process-based, hybrid and data-driven water quality models across diverse hydrological and climatic conditions.

References

¹Jones, E. R., Graham, D. J., van Griensven, A., Flörke, M. & van Vliet, M. T. H. Blind spots in global water quality monitoring. Environmental Research Letters 19, 091001 (2024). https://doi.org:10.1088/1748-9326/ad6919

²Kratzert, F. et al. Caravan - A global community dataset for large-sample hydrology. Scientific Data 10, 61 (2023). https://doi.org:10.1038/s41597-023-01975-w

³Jones, E. R., Kratzert, F. & van Vliet, M. T. H. Caravan-Qual: A global scale integration of water quality observations into a large sample hydrology dataset. Zenodo [DATASET] (2025). https://doi.org:10.5281/zenodo.17787066