Königshafen Submarine Groundwater Discharge Network (KiSNet)

• Applicant: Dr. Ulf Mallast
• Subject Area: Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management
• Term: from 2019 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 437385420

Submarine groundwater discharge (SGD) as a pathway for water and chemical constituents between land and ocean is a rather young topic, but its influence on nutrient cycles on a global scale, is likely to be as significant as the input from rivers. Yet, despite the importance, so far reported SGD flux data contain large uncertainties, either because they were up-scaled from local point measurements to regional scales or because they were derived from modelling/ budgeting of regional or even global matter fluxes. These uncertainties stem from three aspects: 1) methods to retrieve fluxes differ without knowing how each method and flux results relate to each. In turn, an SGD flux comparison across methods is rarely possible. 2) SGD flux measurements are point measurements conducted over short periods of time. In turn, existing spatiotemporal SGD variability is neglected resulting in not generally representative flux measurement, 3) SGD investigations are mostly disciplinary (either marine or terrestrial) although further methods from other disciplines exist. If investigations are interdisciplinary, inherited method-related uncertainties would be reduced which is utterly needed against the background of global change, which particularly affects coastal regions. The proposed network aims to provide the needed platform for an interdisciplinary group of SGD experts to initiate and intensify collaborative ties across disciplines. It also seeks for an improvement of individual methodologies using an interdisciplinary groundtruthing and thus intercomparison between methods of terrestrial and marine disciplines. Finally, the network will create an interdisciplinary method catalogue which outlines optimal combinations for qualitative an quantitative SGD investigations that will be the basis for future SGD research.To reach these aims, the network will be established around regular meetings of which four are face-to-face meetings. The first and last meetings are a kick-off and result meeting respectively. The second and third meeting serve for an intercomparison experiment at the intertidal bay of Königshafen, Sylt. During the experiment the interdisciplinary network of SGD experts will apply several quantitative and qualitative methods from the terrestrial and marine disciplines at the same site and at the same time for the first time. As a result, this course of action will bring together young and experienced scientists from all SGD-relevant marine and terrestrial disciplines, but it will also help to broaden SGD knowledge for all network members, and it will confront the next generation of SGD researchers with an interdisciplinary view of SGD. Second, the method intercomparison experiment will create data sets that are unique in their interdisciplinary nature. The datasets will be published in international peer-reviewed and open-access journals and we plan to produce a detailed, open-access SGD method catalogue analogous to the GEOTRACES CookBook.

• DFG Programme: Scientific Networks
• Co-Investigators: Professor Dr. Nils Moosdorf; Dr. Hannelore Waska