Current activities

Microplastics in groundwater?

Plastic waste is present in the environment and in our waters. In Switzerland, more than 5000 tons are released annually and end up in the environment. Of this, about 600 tons of microplastics end up in the soil and almost 15 tons in the waters. (More than 5000 tons of plastic released into the environment annually, Empa, 2019).

The World Health Organization (WHO) states that based on the limited information available, microplastics in drinking water do not appear to pose a risk to humans today. Other contaminants are much more significant. However, further research is urgently needed. In an investigation by the Office for Waste, Water, Energy and Air (AWEL) in the canton of Zurich, no microplastics were detected in groundwater and drinking water (technical article Microplastics in Wastewater and Waters, Aqua&Gas No 7/8, 2016). Whether nanoplastics can also be efficiently retained in drinking water treatment is currently being investigated within a collaboration Eawag - Wasserversorgung Zürich (WVZ).

CH-GNet is investigating at various sites in Switzerland whether microplastics can enter groundwater. Examples can be found below.

CH-GNet, together with Hardwasser AG and Eawag, Department of Process Engineering with Ralf Kägi, is investigating whether microplastics occur in groundwater and whether they are retained in the respective process stages. In the study area, pretreated Rhine River water is discharged by seepage into the Hardwald forest and later pumped up from the depths of the Hard subsoil as groundwater. Subsequent treatment via an activated carbon filter removes trace impurities.
The different process stages for drinking water production can be divided as follows for an overview:

  • Raw water withdrawal from the Rhine River
  • Pre-treatment
  • Rapid filtration to produce filtrate or service water
  • Infiltration in the Muttenzer Hard
  • Groundwater extraction
  • Activated carbon filtration and disinfection with UV light
  • Storage and discharge

CH-GNet, together with the University of Birmingham, School of Geography, Earth and Environmental Sciences with the Ecohydrology and Biogeochemistry group, is jointly investigating the amount of plastics within the Thur River and the extracted groundwater.

The CH-GNet platform regularly offers webinars on various topics.

The webinars are intended to promote exchange and inform about current studies and developments. A common understanding of the problem is to be developed.  In this way, the critical points and gaps are to be addressed and defined together. It should show possibilities and ways what it needs to guarantee a sustainable groundwater use . Here, the perspectives between water suppliers, agriculture, urban development, science and also the federal government, cantons and practice should flow together.

Current webinars can be found below:

Within the webinars, the conflicts and challenges, but also possible sustainable solutions to divers  topics of, for example, Nitrate and plant protection products (PPP) will be presented and discussed. The aim is to illuminate the different fields of encounter from a scientific point of view. A common understanding of the problem is to be developed, which includes scientific but also perspectives and challenges of practice. The breadth and complexity of the problems and challenges between groundwater use and agriculture generates land conflicts and the need for sustainable and viable development options and solutions will increase.

Date: Monthly webinar (last Thursday of every month).

Time: 13:00 - 14:00

Schedule: Presentation of ~ 20-25 min with 2-3 predefined theses. Theses will be delivered by speakers*. Followed by a question and discussion session after the presentation.

The thematic issue "Groundwater and Agriculture" in the journal Grundwasser is planned for early 2023.

Groundwater is not only a drinking water resource, but also an essential basis of valuable aquatic ecosystems in rivers, lakes and wetlands. However, the pollution of groundwater by agricultural activities has been a major problem for sustainable water management for decades. To date, the main focus has been on large-scale water quality pollution from pollutant inputs, but projected increased water demands for irrigated agriculture also pose challenges to the availability of groundwater resources.

Nitrate and pesticide residues in particular can affect groundwater quality. Here, among other factors, livestock numbers and the resulting amount of manure play a significant role in the level and spatial distribution of nitrogen inputs. In this context, monocultures in agriculture must also be critically evaluated, as they are associated with increased fertilizer requirements and plant protection products (PPP) applications. In addition, heavy metals from fertilizers, critical organic substances, residues of veterinary drugs and microplastics from e.g. sewage sludge can endanger groundwater quality. In recent years, important scientific findings have been made on the interplay between agriculture and groundwater, but it is apparent that translating these into specific measures often proves difficult and lengthy. Because groundwater resources are slow to renew and can have long residence times, proactive measures are needed to protect and conserve groundwater resources, especially in the face of changing boundary conditions. In the wake of climate change and the threat of longer periods of drought, it is foreseeable that agriculture will make greater use of groundwater resources for the irrigation of agricultural land in the future. Energy crops could also increasingly compete with food production. This raises questions about the sustainability of agriculture and water use conflicts. Changing water flows in soil and groundwater due to climate change and irrigation also suggest feedbacks with water quality. In particular, effects of droughts and extreme precipitation events on nutrient and pollutant transport and retention are not fully understood.

This thematic issue is intended to address the breadth and complexity of the problems of agriculture, groundwater quality and quantity, offer approaches to solutions, and provide space for perspectives from the scientific community, policy makers, as well as challenges from practitioners. In this regard, contributions on the current state of research as well as practical implementation are welcome. We also encourage submissions on innovative measurement techniques, numerical and data-driven modeling approaches at various spatio-temporal scales, and advanced method development.

Important dates and information:

  • Expressions of interest with preliminary title and abstract by the end of April 2022.
  • Submission of manuscripts by the end of June 2022.
  • Review and revision of manuscripts by mid-November 2022.
  • Publication of the thematic issue in March 2023
  •  Guidelines for authors

Guest Editors/Contact:

Dr. Andreas Musolff

  • Helmholtz-Zentrum für Umweltforschung (UFZ)
  • Contact:

CH-GNet is actively involved with partners from enforcement, practice, water supply to produce opinion and position papers to systematically look at critical points and controversial issues and their development from different perspectives. With these articles we want to contribute to close gaps between practice, enforcement and science and to initiate necessary developments.

Current position papers can be found below:

  • Groundwater Modeling - Benefits of Quantifying Uncertainty.
  • A real-time online method for assessing artificial groundwater recharge and extraction.


Groundwater modeling is routinely applied to diverse problems in environmental and groundwater management. Reliable quantification of hydrogeological processes using groundwater models often forces us to generate a continuous three-dimensional (3D) conceptualization and associated model parameter distribution, whereas direct subsurface measurement data are generally sparse and spotty. Also, groundwater models have traditionally been calibrated exclusively against groundwater level measurements, although it has been repeatedly demonstrated that these classic observations do not contain sufficient information to provide an appropriate parameterization for most modeling tasks. Because often only point observations of classical groundwater state variables are available, in most cases several model parameter sets are equally capable of reproducing the measured data. Because of this ambivalence of measured data with respect to model parameterization, it is often not possible to identify a single best model. Therefore, while it is common in academic applications to use multiple equally calibrated model parameter sets to reliably quantify the uncertainties of groundwater models, this is rarely done in practice. The reasons for this are manifold. With this article we want to contribute to closing this gap between practice and science. Using three selected case studies from Switzerland, we demonstrate the advantages of systematically quantifying the uncertainty of groundwater models and providing a detailed description of the heterogeneity of the subsurface. We show how the insights gained can help decision makers better understand the overall reliability of model predictions and identify specific strengths and weaknesses of a model. In addition, we show how careful and forward planning of the measurement data to be collected can substantially reduce the uncertainty of groundwater models.


  • Christian Moeck, Mario Schirmer, Eawag
  • Oliver Schilling, Philip Brunner, CHYN - University of Neuchâtel
  • Rouven Künze, TK CONSULT AG


A sustainable water supply in urban areas is a major challenge due to the pressure of use as well as diverse anthropogenic inputs. Artificial groundwater recharge has the potential to meet water demand and dilute any pollutant concentrations that may be present. High infiltration rates can also create a hydraulic barrier to pollutants from adjacent land uses. The basic prerequisite for using this barrier as effectively as possible is the precise description of the spatial and temporal distribution and the recording of the areas in which the protective function is reduced by the barrier.
In the case study described for a drinking water extraction area in northern Switzerland, we present a simple online tool. It can be used to complement the large amount of collected data to digitize and interpret contour maps by simplifying the analysis of collected data and visualizing groundwater flow directions and magnitudes. The results can be used to describe more complex flow systems, leading to more efficient groundwater monitoring.


  • Christian Moeck, Mario Schirmer, Eawag
  • Markus Merk, Karlsruhe Institute of Technology (KIT)
  • Dirk Radny, Federal Institute of Hydrology (BfG)
  • Adrian Auckenthaler, Office for Environmental Protection and Energy Basel-Landschaft
  • Thomas Gabriel, Hardwasser AG

A total of 30 groundwater monitoring sites were selected from the National Groundwater Monitoring NAQUA dataset to investigate groundwater dynamics including effects of snowmelt, groundwater recharge, and climate sensitivities of the respective monitoring sites.

Sites cover a wide range of elevations, with alpine aquifers (max. 1700 m) in the southeast and large alluvial aquifers in the north (min. 277 m). A summary of hydrogeologic and meteorologic conditions at each site is provided in the following figures.

The use of time series modeling methods is becoming increasingly popular to obtain an initial assessment of the groundwater system. The methods can be used to solve groundwater problems without the need to create an elaborate numerical groundwater model. CH-GNet uses time series models to simulate historical groundwater levels to make water level predictions. For this purpose, we use the nonlinear recharge model developed by  Collenteur et al. 2019.

We apply time series models to

  • Predict groundwater levels within seconds for an area of artificial groundwater recharge that is highly dependent on large amounts of infiltration and withdrawal.
  • Filling data gaps.
  • Quantify the influence of groundwater withdrawal volumes, variations in river/channel water levels, and climatic conditions.
Letzte Änderung: 13.10.2022