ESSDD Earth System Science Data Discussions ESSDD Earth Syst. Sci. Data Discuss. 1866-3591 Göttingen, Germany 10.5194/essd-2025-608 CAMELS-GB v2: hydrometeorological time series and landscape attributes for 671 catchments in Great Britain Coxon Gemma https://orcid.org/0000-0002-8837-460X 1 Zheng Yanchen https://orcid.org/0000-0002-2212-9134 1 2 Barbedo Rafael https://orcid.org/0000-0002-3910-9244 3 Cooper Hollie https://orcid.org/0000-0002-1382-3407 3 Fileni Felipe 4 Fowler Hayley J. https://orcid.org/0000-0001-8848-3606 4 Fry Matt https://orcid.org/0000-0003-1142-4039 3 Green Amy 4 Gribbin Tom 5 Harfoot Helen 6 7 Lewis Elizabeth https://orcid.org/0000-0002-7471-9988 8 Neto Germano Gondim Ribeiro https://orcid.org/0000-0002-0823-0885 1 Qiu Xiaobin 4 Salwey Saskia https://orcid.org/0000-0002-2100-3142 2 9 Wendt Doris E. 1 10 School of Geographical Sciences, University of Bristol, Bristol, UK School of Civil, Aerospace and Design Engineering, University of Bristol, Bristol, UK UK Centre for Ecology & Hydrology, Maclean Building, Crowmarsh Gifford, Wallingford, United Kingdom School of Engineering and Tyndall Centre for Climate Change Research, Newcastle University, Newcastle upon Tyne, United Kingdom British Geological Survey, Keyworth, United Kingdom Environment Agency, Romsey, Hampshire, United Kingdom School of Geography and Environmental Science, University of Southampton, Highfield, Southampton, United Kingdom Civil Engineering and Management, University of Manchester, Manchester, United Kingdom Department of Physical Geography, Faculty of Geosciences, Utrecht University, Utrecht, the Netherlands British Geological Survey, Edinburgh, United Kingdom 27 11 2025 2025 1 44 Copyright: © 2025 Gemma Coxon et al. 2025 This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/ This article is available from https://essd.copernicus.org/preprints/essd-2025-608/ The full text article is available as a PDF file from https://essd.copernicus.org/preprints/essd-2025-608/essd-2025-608.pdf

Large-sample hydrological datasets containing data for tens to thousands of catchments are invaluable for hydrological process understanding and modelling. CAMELS (Catchment Attributes and MEteorology for Large-sample Studies) datasets provide hydro-meteorological timeseries, catchment attributes and catchment boundaries. Here, we present the second version of CAMELS-GB. CAMELS-GB v2 collates millions of observations from across Great Britain at hourly to monthly timescales, including quality-controlled daily river flows, catchment boundaries, and catchment characteristics from the UK National River Flow Archive. The new features include (1) extended daily hydro-meteorological timeseries from 1970&ndash;2022 including meteorological timeseries from new observed climate datasets, (2) new hourly precipitation, river flow and level timeseries, (3) new groundwater level timeseries and attributes for 55 groundwater wells, and (4) new catchment attributes characterising changing land cover, peak flows and human influences. These data are provided for 671 catchments across Great Britain spanning a diverse range of geophysical characteristics and human influences. CAMELS-GB v2 represents a step change for environmental and modelling analyses across Great Britain, particularly for the characterisation of sub-daily hydrological processes, and is made available as an open dataset (Coxon et al., 2025; <a href="https://doi.org/10.5285/9a46d428-958f-4ac1-86eb-94eee70c0955" target="_blank" rel="noopener">https://doi.org/10.5285/9a46d428-958f-4ac1-86eb-94eee70c0955</a>).

 Medical Research Council MR/V022857/1 Natural Environment Research Council NE/X018865/1 NE/S007512/1 Science and Technology Facilities Council ST/Y003713/1 European Research Council 101075354