Integrated Hydrological Modelling for Operational Forecasting and Decision-making

80% of Switzerland's drinking water is originating from groundwater. Climate change-induced droughts and increased demand for irrigation put groundwater under considerable pressure and cause widespread concern. In 2021, two popular initiatives were launched to protect groundwater and 2 parliamentary motions concerning groundwater were accepted in 2022/23. Now, for more than 3000 wells capture zones have to be delineated until 2035, and 4000km of rivers have to be restored within the next 70 years. Groundwater modelling plays an important role in tackling these challenges. However, the robustness of the current modelling practice is undermined by the poor characterisation of the subsurface, the computational challenges to jointly simulate surface- and groundwater and by the large resulting uncertainties. Consequently, stakeholders have to deal with complex issues but cannot fully exploit the potential of modelling to help them make relevant decisions.

In this project, we are addressing these shortcomings by (1) Employing cutting-edge mass-spectrometry technology to expand the available tracer methods with non-toxic gas tracers injected into the subsurface. This will greatly expand the spatial and temporal scales of available tracer methods and open new pathways to subsurface characterisation. (2) Building on the latest generation of integrated surface-subsurface hydrological models (ISSHM). This will allow joint consideration of the surface, the subsurface, and the operational infrastructure. Through the direct simulation of tracers, the model calibration is also far more robust and unique. (3) Providing the technological and computational means for real-time data assimilation in ISSHMs. This will guarantee that the model is always close to the real system state and thus can be continuously used to support operational decision-making. We have demonstrated the technical feasibility of all of these developments in our previous work.

This BRIDGE Discover project allows us to move this fundamental research to an operational level by collaborating among the three institutions through 12 coordinated work packages. In close collaboration with the relevant stakeholders, we develop and assess the efficiency of our hydrogeological service for two pilot studies: one to increase the efficiency of irrigation for agriculture, and the second one to predict the influence of a renaturation on well capture zones.