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

Abstract. Openly accessible global-scale surface water chemistry datasets are urgently needed to detect widespread trends and problems, help identify their possible solutions, determine critical spatial data gaps where more monitoring is required. Existing limited with respect availability, sample size and/or sampling frequency, geographic scope. These limitations inhibit researchers from tackling emerging transboundary issues – for example, the detection understanding of delayed recovery freshwater acidification. Here, we begin address these by compiling global Surface Water Chemistry (SWatCh) database, available on Zenodo (https://doi.org/10.5281/zenodo.6484939; Rotteveel Heubach, 2021). We collect, clean, standardize, aggregate open-access provided six national international programs research groups (United Nations Environment Programme; Hartmann et al., 2019; Climate Change Canada; United States America National Quality Monitoring Council; European Agency; Science Foundation McMurdo Dry Valleys Long-Term Ecological Research Network) in order compile a database containing information sites, methods, samples, geospatial system (GIS) shapefile site locations. remove poor-quality (e.g., values flagged as “suspect” or “rejected”), standardize variable naming conventions units, perform other cleaning steps required statistical analysis. The contains streams, rivers, canals, ponds, lakes, reservoirs across seven continents, 24 variables, 33 722 over 5 million samples collected between 1960 2022. Similar prior research, African Asian highlighting need collection sharing initiatives areas, especially considering that ecosystems environs predicted be among most heavily impacted climate change. main challenges associated databases dissimilar analysis methodology, reporting ambiguity provide recommended solutions. By addressing consolidating various sources into one standardized, openly available, high-quality, SWatCh allows users conduct powerful robust analyses chemistry.