Karlsruher Institute for Technology: Reservoirs: Protecting the resource water more easily

Reservoirs are indispensable for the supply of drinking water worldwide. In order to protect the reservoirs from silting up, over-fertilization and contamination by pollutants, their water quality must be carefully monitored. A German-Brazilian consortium led by the Karlsruhe Institute of Technology (KIT) has developed easy-to-use measurement and monitoring methods that are particularly suitable for regions with limited data availability. The project results show, among other things, how effective targeted reforestation is in the catchment area of reservoirs.

If a deterioration in water quality is detected early on, measures can be implemented in good time and endangered reservoirs can be preserved for longer. Environmental models support the observation and assessment of substance input and water quality. However, previous models require very large amounts of data and a high level of technical measurement effort; this makes them unsuitable for use in data-poor regions. The interdisciplinary project “Multidisciplinary data acquisition as the key for a globally applicable water resource management” (MuDak-WRM) has developed monitoring approaches, models and measurement techniques that are as simple and generally available as possible in three and a half years of research in Brazil and Germany. Satellite data were used both to calculate the water balance – the difference between water uptake and release – and to calculate the substance inputs from the catchment area. “We have seen that meaningful results can be achieved with less data,” says Dr. Stephan Hilgert, geoecologist at the Institute for Water and Water Development (IWG) of the KIT and coordinator of the project.

Automation of data processing

A large number of different information flows into the previous substance input model. Therefore, the project team concentrated on the two most important entry paths: the substance entry through erosion of the land surface and the waste water entry from the urban environment in the inflow area of reservoirs. The large Dhünntalsperre in North Rhine-Westphalia and the Passaúna reservoir in the Brazilian state of Paraná were examined as examples.

“A key point was the automation of the processing of satellite data that is used to calculate the water balance and the input of substances such as phosphorus and solids,” explains Hilgert. The successful automation significantly simplifies the application of the models and increases their accuracy and transferability to other catchment areas. The consortium of science, municipal associations and industrial companies has developed sensors and platforms for the continuous recording of water quality and developed an online platform (Sensor Web) with which the data can be recorded, saved and evaluated in a user-friendly manner.

Effect of afforestation calculated

The project results show, among other things, that afforestation of only three percent of the agricultural area in the catchment area of the Passaúna reservoir can lead to a reduction in sediment input of up to 26 percent. “The silting up of reservoirs, as a result of which their storage volume is reduced, is a fundamental problem for the coming decades, because humanity is currently losing more storage volume than is being added,” says Hilgert.

Further studies have shown that nutrients bound in the sediment can in future deteriorate the water quality due to climate change in the deeper layers of reservoirs. “In the subtropics, there is a lot of phosphorus-binding iron in the soil and thus also in the reservoir sediment. However, iron only binds phosphorus as long as there is sufficient oxygen in the water. If oxygen is missing for a long time when the water temperature rises, the phosphorus can dissolve, which suddenly leads to a massive increase in cyanobacteria, the algal bloom, and the water tilts, ”explains the geoecologist. In order to recognize this danger in good time, reservoir operators would have to monitor the state of the water and the composition of the sediment inside the lake in addition to evaluating satellite images, says Hilgert.

The MuDak-WRM project

The Federal Ministry of Education and Research (BMBF) funded the MuDak-WRM project, which began in 2017 and ended in 2021, with 2.6 million euros as part of the GROW (Global Resource Water) funding measure as part of the “FONA – Research for Sustainability” program. The two departments of the IWG Urban Water Management and Water Quality Management as well as Water Management and Cultural Technology as well as the Institute for Photogrammetry and Remote Sensing (IPF) were involved at KIT. On the German side, the research consortium included the University of Koblenz-Landau, the Wupperverband and the companies 52 ° North – Initiative for Geospatial Open Source Software GmbH, EFTAS Fernerkundungs-Technologietransfer GmbH, Hydron GmbH and TRIOS Mess- und Datentechnik GmbH. On the Brazilian side, the State University of Paraná (UFPR) and the University of Positivo as well as the water utility SANEPAR were actively involved. Associated partners in Brazil were the Instituto Paranaense de Assistência Técnica e Extensão rural (Paranaensic Institute for Rural Development, EMATER) and the Instituto das Aguas do Paraná (Water Institute of the State of Paraná).

Details on the KIT Climate and Environment Center: www.klima-umwelt.kit.edu

As “The Research University in the Helmholtz Association”, KIT creates and imparts knowledge for society and the environment. The aim is to make significant contributions to global challenges in the fields of energy, mobility and information. To this end, around 9,600 employees work together on a broad disciplinary basis in the natural, engineering, economic, humanities and social sciences. The KIT prepares its 23,300 students for responsible tasks in society, economy and science through a research-oriented university course. The innovation activity at KIT bridges the gap between knowledge and application for social benefit, economic prosperity and the preservation of our natural foundations of life.

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