Large-sample datasets are essential in hydrological science to support modelling studies and global assessments. The present dataset compiles all freshwater quality data that is available under open data policy (CC BY 4.0 or equivalent) at the GEMStat database for global water quality (www.gemstat.org). It includes over 20,000,000 measurements on 608 water quality parameters, covering 13,660 stations in 37 countries over the time period from 1906 to 2023.

GEMStat is operated by the GEMS/Water programme of the United Nations Environment Programme (UNEP) and hosted at the International Centre for Water Resources and Global Change (ICWRGC) and the German Federal Institute of Hydrology (BfG). The data in GEMStat is provided by National Hydrological Services of UN member states.

This dataset comprises data from the GEMStat database that are available under an open data license (CC BY 4.0 or equivalent). It is made available on the Zenodo repository. GEMStat provides access to freshwater quality data. The data are voluntarily provided by countries and organizations worldwide within the framework of the GEMS/Water Programme of the United Nations Environment Programme (UNEP). The dataset includes more than 20 million measurement from over 13,000 stations and covering more than 600 different parameters and spans the time period from 1906 to 2023. This represents over 70% of all GEMStat data, further data is only available under more restricted data licenses. GEMStat is operated by the GEMS/Water programme of the United Nations Environment Programme (UNEP) and hosted at the International Centre for Water Resources and Global Change (ICWRGC) and the German Federal Institute of Hydrology (BfG). The data in GEMStat is provided by National Hydrological Services of UN member states.

Water quality data available from GEMStat can be used for status evaluation, research purposes or within the scope of education and training initiatives. For data sets not available online through the Data Portal or Statistics Portal, requests made by non-commercial and non-private persons (i.e. those with no affiliation) will be filled at no cost, but will depend on data availability, UN Environment GEMS/Water Programme workload, and the nature of the data set/product being requested. Requests will be queued with priority given to those related to joint activities with UN Environment Programme areas and other UN agencies. Data sets with a “Restricted” access rating will not be distributed; however, information about such data sets, including the distributor’s name and summary statistics on country level, can be sent to eligible institutions upon request.

The United Nations Environment Programme Global Environment Monitoring System (GEMS) Water Programme is a multi-faceted water science centre oriented towards building knowledge on inland quality issues worldwide. The twin goals of the programme are to improve water quality monitoring and assessment capacity in participating countries, and to determine the state and trends of regional and global water quality.

GEMStat.org is designed to provide access to surface and groundwater quality data and statistics collected from the GEMS/Water Global Network, and warehoused in a global water quality database called GEMStat. The Global Network covers over 80 countries, 1,400 stations, two million records, and over 100 parameters.

A major problem related to large-scale water quality modeling has been the lack of available observation data with a good spatiotemporal coverage. This has affected the reproducibility of previous studies and the potential improvement of existing models. In addition to the observation data itself, insufficient or poor quality metadata has also discouraged researchers to integrate the already available datasets. Therefore, improving both the availability and quality of open water quality data woould increase the potential to implement predictive modeling on a global scale. We aim to address the aforementioned issues by presenting the new Global River Water Quality Archive (GRQA) by integrating data from five existing global and regional sources: Canadian Environmental Sustainability Indicators program (CESI), Global Freshwater Quality Database (GEMStat), GLObal RIver Chemistry database (GLORICH), European Environment Agency (Waterbase) and USGS Water Quality Portal (WQP). The resulting dataset covering the timeframe 1898 - 2020 contains a total of over 17 million observations for 42 different forms of some of the most important water quality parameters, focusing on nutrients, carbon, oxygen and sediments. Supplementary metadata and statistics are provided with the observation time series to improve the usability of the dataset.

Last update: 2022-03-11

GRQA_v1.2 contains three updated files compared to GRQA_v1.1:

• NH4N_GRQA.csv
• NO2N_GRQA.csv
• NO3N_GRQA.csv

The files were updated, because the assumed conversion constants used for the corresponding GLORICH observations were found to be incorrect. The corresponding files in GRQA_figures.zip and GRQA_meta.zip are yet to be updated, but will be in GRQA_v1.3.

The explanation for the updated conversion constants is given in this notebook:
https://nbviewer.org/github/LandscapeGeoinformatics/GRQA_src/blob/main/testing/glorich_conversion_test.ipynb

An overview of all the files in the dataset can be found in README_v1.2.txt.

Statistical overview of all 42 parameters is given in the data catalog file GRQA_data_catalog.pdf.

For more information about the development of this dataset look for Virro, H., Amatulli, G., Kmoch, A., Shen, L., and Uuemaa, E.: GRQA: Global River Water Quality Archive, Earth Syst. Sci. Data, 13, 5483–5507, https://doi.org/10.5194/essd-13-5483-2021, 2021.

These files represent the raw data used to generate a global model of median dissolved and total nitrogen and phosphorus concentrations. This was used in an assessment of the likelihood of periphyton growth.Prospective users are to acknowledge and abide by the policies of the data providers (e.g. GEMStat.org; www.lawa.org.nz etc). Use of this processed database should acknowledge the authors.

The United Nations GEMS/Water Programme provides scientifically-sound data and information on the state and trends of global inland water quality required as a basis for the sustainable management of the world's freshwater to support global environmental assessments and decision-making processes.

GEMS/Water is hosted by Environment Canada at the National Water Research Institute (NWRI) and operates under the auspices of the United Nations Environment Programme. Maintained at NWRI is the GEMS/Water data warehouse, GEMStat. GEMStat is designed to share surface and ground water quality data sets collected from the GEMS/Water Global Network, including over 2,700 stations, two million records, and over 100 parameters.

DISCLAIMERS:The designations employed and the presentation of material on this map do not imply the expression of any opinion whatsoever on the part of the Secretariat of the United Nations concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.Final boundary between the Republic of Sudan and the Republic of South Sudan has not yet been determined.Final status of the Abyei area is not yet determined.* Dotted line represents approximately the Line of Control in Jammu and Kashmir agreed upon by India and Pakistan. The final status of Jammu and Kashmir has not yet been agreed upon by the parties.** Chagos Archipelago appears without prejudice to the question of sovereignty.*** A dispute exists between the Governments of Argentina and the United Kingdom of Great Britain and Northern Ireland concerning sovereignty over the Falkland Islands (Malvinas).

This dataset provides information about the number of properties, residents, and average property values for Gemstar Road cross streets in Reynoldsburg, OH.

DISCLAIMERS:The designations employed and the presentation of material on this map do not imply the expression of any opinion whatsoever on the part of the Secretariat of the United Nations concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.Final boundary between the Republic of Sudan and the Republic of South Sudan has not yet been determined.Final status of the Abyei area is not yet determined.* Dotted line represents approximately the Line of Control in Jammu and Kashmir agreed upon by India and Pakistan. The final status of Jammu and Kashmir has not yet been agreed upon by the parties.** Chagos Archipelago appears without prejudice to the question of sovereignty.*** A dispute exists between the Governments of Argentina and the United Kingdom of Great Britain and Northern Ireland concerning sovereignty over the Falkland Islands (Malvinas).