press release, 06. October 2023

New analysis on current and future global water quality available

Remote sensing and modeling can bridge the blind spots in water quality monitoring.

Globally, approximately 40 percent of domestic wastewater is still discharged untreated. At the same time, reliable information on water quality in rivers and lakes is lacking, especially in developing and emerging countries. Therefore, the World Water Quality Alliance, a consortium initiated by the UN Environment Programme, advocates for the necessary attention to be given to water quality. The research project GlobeWQ, coordinated by the Helmholtz Centre for Environmental Research (UFZ) and funded by the German Federal Ministry of Education and Research (BMBF), contributes to the efforts of the World Water Quality Alliance. The research team has been able to demonstrate, on a global scale and through various application examples, how innovative combinations in-situ data, remote sensing data, and water quality modeling can better determine the water quality of water bodies and the associated risks to humans and the environment compared to previous methods. The results of this work have now been published in the project's final report.

Satellite image of Kisumu Bay on Lake Victoria which is frequently subject to algal blooms. Photo: EOMAP GmbH & Co. KG
Satellite image of Kisumu Bay on Lake Victoria which is frequently subject to algal blooms.
Photo: EOMAP GmbH & Co. KG

Water is the foundation of all life. Ensuring an adequate supply of high-quality water for both humans and nature is therefore essential. "Clean water and sanitation for all" is goal number 6 out of a total of 17 Sustainable Development Goals (SDGs) of the United Nations, which are to be implemented within the framework of the 2030 Agenda. "The sixth Sustainable Development Goal also includes the protection of water-dependent ecosystems and the safeguarding of water quality for both humans and the environment," says Prof. Dietrich Borchardt, Head of the UFZ Research Unit Water Resources and Environment. "However, in many places, especially in developing and emerging countries, there is a lack of information for assessing water quality. In addition, regular water monitoring with sampling and laboratory analyses is time-consuming and expensive - and therefore not feasible in all places in the world."

The GlobeWQ project addresses these global data and information gaps in water quality. "By combining field measurement data, remote sensing, and water quality modeling, we aimed to obtain a more comprehensive and coherent picture of the state of water bodies and gain insights into their key influencing factors," says project leader Dietrich Borchardt. Together with local users, the researchers developed and tested various regional application examples for the GlobeWQ analysis and service platform: Lake Victoria in Africa, Lake Sevan in Armenia, and the Elbe River in Germany. For each case, the researchers combined on-site measurement data from the global database (GEMStat) with Sentinel-2 satellite imagery and modeling. "Remote sensing enables optical measurements, such as assessing turbidity, visibility, and chlorophyll-a content as an indicator of algae presence in the water," says UFZ hydrogeologist Dr. Christian Schmidt, GlobeWQ coordinator. For Lake Victoria, where harmful algal blooms affecting fishing are a recurring issue, GlobeWQ provides timely and widespread information on chlorophyll-a concentrations, allowing for the early detection of algal bloom risks. The risk of harmful algal blooms also exists in the Elbe River. "In collaboration with the Elbe River Basin Community, we created a prototype within the project, providing reliable information on the temporal and spatial patterns of algal blooms within the river system," says the UFZ researcher.

Until now, data from on-site measurements have been considered the gold standard for assessing water quality. However, the GlobeWQ project's application examples demonstrate that remote sensing data and water quality modeling can complement these measurements effectively, closing data gaps and allowing for the assessment of water quality of water bodies. "In principle, it's similar to weather forecasting," says hydrobiologist Dietrich Borchardt. "The additional high-resolution information provides significant added value that we should use to better assess and predict water quality spatially and temporally, and to improve it through more targeted measures in the future." This method has also been picked up and further developed by German companies involved in the project. It was successfully applied, for example, in investigating the causes of fish deaths in the Odra River in the summer of 2022.

In addition to the regional application examples, the GlobeWQ project expanded the water quality model WorldQual developed by Ruhr University Bochum. "With the WorldQual model, it's possible to simulate, on a monthly basis, the development of certain parameters that are important for assessing water quality," explains Christian Schmidt. These parameters include biological oxygen demand, the presence of indicator organisms for fecal contamination, and phosphorus content. "Until now, WorldQual simulations were only possible for rivers in South America, Africa, or parts of Asia. Within the GlobeWQ project, we expanded the model to work globally." Dietrich Borchardt adds, "This means that, for the first time, model data are available for previously blank spots on the water quality world map, allowing for a comprehensive assessment of river water quality globally. It becomes easier to identify where it is particularly important to reduce inputs from agriculture or to build wastewater treatment plants." Water quality modeling also allows for predictions about the future development of global water quality under the conditions of population growth and climate change. The analysis gives cautious cause for hope that the burden of coliform bacteria (resulting from fecal contamination) will decrease worldwide by 2040 due to improved wastewater treatment, with the exception of Africa. There, contamination is expected to increase until 2060 but then steadily decrease.

The GlobeWQ research project was funded by the German Federal Ministry of Education and Research (BMBF) as part of the BMBF funding program "Global Resource Water (GRoW)." The project consortium includes UFZ, the United Nations Environment Programme (UNEP), Ruhr University Bochum, the International Centre for Water Resources and Global Change (ICWRGC), as well as the companies Earth Observation & Environmental Services (EOMAP) and terrestris GmbH & Co. The German Environment Agency (UBA) and the European Environment Agency (EEA) support the project in connecting to practical management as strategic partners.

Final report:

More information:

Further information

Dr. Christian Schmidt
UFZ Department Hydrogeology

Prof. Dr. Dietrich Borchardt
Head of UFZ Research Unit Water Resources and Environment

UFZ press office

Susanne Hufe
Phone: +49 341 235-1630

In the Helmholtz Centre for Environmental Research (UFZ), scientists conduct research into the causes and consequences of far-reaching environmental changes. Their areas of study cover water resources, ecosystems of the future, environmental technologies and biotechnologies, the effects of chemicals in the environment, modelling and social-scientific issues. The UFZ employs more than 1,100 staff at its sites in Leipzig, Halle and Magdeburg. It is funded by the Federal Government, Saxony and Saxony-Anhalt.

The Helmholtz Association contributes to solving major challenges facing society, science and the economy with top scientific achievements in six research fields: Energy; Earth and Environment; Health; Key Technologies; Matter; and Aeronautics, Space and Transport. With some 39,000 employees in 19 research centres, the Helmholtz Association is Germany’s largest scientific organisation.
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