Toward a National Understanding of River Chemistry: Analyzing Water Quality Baselines and Controls across Great Britain from the new CAMELS-GB-Chem dataset

Hydrological research increasingly benefits from large-sample datasets for better understanding and modelling hydrological processes. Recent studies have shown how compiling and integrating large-scale water quality datasets can shed new light on water quality baseline conditions and understanding its controls. However, large-sample water quality datasets remain relatively scarce despite rising global river pollution.

In this study, we compiled around 64 million water quality records for Great Britain’s rivers by harmonising different datasets provided by Natural Resources Wales (NRW) and the Environment Agency of England. We matched these water quality records to existing catchments within CAMELS-GB, a large-sample hydrology dataset containing hydro-meteorological timeseries and catchment attributes for 671 catchments across Great Britain. We applied rigorous quality assurance and control procedures to account for detection limits, outliers, and duplicate entries in the water quality time series. We aim to release this harmonized CAMELS-GB-Chem dataset for national-scale analyses of river water quality.

Using the new CAMELS-GB-Chem dataset, we characterize baseline water quality and trends across Great Britain. We then explore whether these baseline conditions can be linked to catchment attributes such as climatic indicators, hydrological signatures, geology, soil properties, land cover and topography. Our preliminary results reveal that climatic variables (e.g., aridity and mean rainfall) and streamflow metrics (e.g., Q95 and mean discharge) are the dominant controls, while land cover, geology, and soils exert varied influence on different water quality indicators. Future work will incorporate anthropogenic influences into our analysis.

In sum, our work not only fills a critical water quality data gap at the national scale but also lays a scientific foundation for monitoring, modelling, and managing the water quality in Great Britain’s rivers under environmental change.