17 Mar 2021
17 Mar 2021
Status: a revised version of this preprint is currently under review for the journal ESSD.

The Surface Water Chemistry (SWatCh) database: A standardized global database of water chemistry to facilitate large-sample hydrological research

Lobke Rotteveel and Shannon M. Sterling Lobke Rotteveel and Shannon M. Sterling
  • Sterling Hydrology Research Group, Dalhousie University, Halifax, B3H 4R2, Canada

Abstract. Openly accessible global scale surface water chemistry datasets are urgently needed to detect widespread trends and problems, to help identify their possible solutions, and identify critical spatial data gaps where more monitoring is required. Existing datasets are limited in availability, sample size/sampling frequency, and geographic scope. These limitations inhibit the answering of emerging transboundary water chemistry questions, for example, the detection and understanding of delayed recovery from freshwater acidification. Here, we begin to address these limitations by compiling the global surface water chemistry (SWatCh) database, available on Zenodo (DOI: We collect, clean, standardize, and aggregate open access data provided by six national and international agencies to compile a database consisting of three relational datasets: sites, methods, and samples, and one GIS shapefile of site locations. We remove poor quality data (for example, values flagged as suspect), standardize variable naming conventions and units, and perform other data cleaning steps required for statistical analysis. The database contains water chemistry data across seven continents, 17 variables, 38,598 sites, and over 9 million samples collected between 1960 and 2019. We identify critical spatial data gaps in the equatorial and arid climate regions, highlighting the need for more data collection and sharing initiatives in these areas, especially considering freshwater ecosystems in these environs are predicted to be among the most heavily impacted by climate change. We identify the main challenges associated with compiling global databases – limited data availability, dissimilar sample collection and analysis methodology, and reporting ambiguity – and provide recommendations to address them. By addressing these challenges and consolidating data from various sources into one standardized, openly available, high quality, and trans-boundary database, SWatCh allows users to conduct powerful and robust statistical analyses of global surface water chemistry.

Lobke Rotteveel and Shannon M. Sterling

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Comment on essd-2021-43', Mary Kruk, 13 Sep 2021
  • RC1: 'Comment on essd-2021-43', Anonymous Referee #1, 11 Dec 2021
  • RC2: 'Comment on essd-2021-43', Anonymous Referee #2, 03 Feb 2022
  • AC1: 'Responses to Community and Reviewer Comments', Lobke Rotteveel, 04 Mar 2022

Lobke Rotteveel and Shannon M. Sterling

Data sets

The Surface Water Chemistry (SWatCh) database Lobke Rotteveel

Model code and software

The Surface Water Chemistry Database (SWatCh) Lobke Rotteveel

Lobke Rotteveel and Shannon M. Sterling


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Short summary
Data is needed to detect environmental problems, find their solutions, and identify knowledge gaps. Existing datasets have limited availability, sample size and/or frequency, or geographic scope. Here, we begin to address these limitations by collecting, cleaning, standardizing, and compiling the Surface Water Chemistry (SWatCh) database. SWatCh contains global surface water chemistry data for seven continents, 17 variables, 38,598 sites, and over 9 million samples collected from 1960 to 2019.