Water use conflicts and related monitoring strategies in an extensively developed groundwater system

In many parts of the world, groundwater resources are under increasing pressure, with both, quantitative and qualitative causes. This can lead to various water use conflicts, especially in densely populated areas. One example of such a region is the Hessian Ried, which is part of the Upper Rhine Valley and located south of Frankfurt in Germany. The Hessian Ried covers an area of approximately 1,100 km² and was naturally mostly marshland. To allow agricultural use, it was largely drained at the beginning of the last century. Today, mainly fruit and vegetables are grown with the extensive use of fertilizers, pesticides and groundwater irrigation. In addition, the relatively dense population in adjacent areas results in the discharge of large amounts of treated municipal wastewater into the streams of the Hessian Ried. Due to widespread influent conditions, there is substantial infiltration of these surface waters into the aquifer. However, the Hessian Ried is of enormous importance for the interregional public water supply in the Rhine-Main metropolitan area, for example, as the primary drinking water supply for the city of Frankfurt.   

It is therefore important to gain an understanding of the processes by which substances are transferred from diffuse (agricultural land) and local (sewage-affected streams) sources into the groundwater and to develop reasonable countermeasures. Subsequently, monitoring tools are required that enable to examine the actual effectiveness of these measures in a timely manner. For this purpose, we have developed and implemented two types of monitoring stations at which (i) the diffuse input of nutrients and pesticides into the groundwater through the soil zone (Richard-Cerda et al., 2022, 2024) and (ii) the infiltration of pharmaceutically active compounds from a stream into the groundwater are studied. Results from the operation of these stations over a period of more than one year and additional laboratory experiments on hyporheic zone processes show initial findings on the sorption, transformation and degradation of nutrients and various organic trace substances.

 

References

Richard-Cerda, J.C., Bockstiegel, M., Muñoz-Vega, E., Knöller, K., Schüth, C., & Schulz, S., (2024). High-Resolution Monitoring and Redox-Potential-Based Solute Transport Modeling to Partition Denitrification Pathways at an Agricultural Site. Environmental Science & Technology Water. https://doi.org/10.1021/acsestwater.4c00540

Richard-Cerda, J.C., Giber, A., Muñoz-Vega, E., Kübeck, C., Berthold, G., Schüth, C., & Schulz, S. (2022). A high-resolution monitoring station for the in situ assessment of nitrate-related redox processes at an agricultural site. Journal of Environmental Quality 52. 188-198. https://doi.org/10.1002/jeq2.20423