Geotechnical Use of Deep Groundwater Systems

In recent years, the deep geological underground gained more and more attention as it offers various reservoirs potentially applicable for different geotechnical use options, e.g. deep geothermal energy or geological storage of CO2 and H2/energy. In this context, knowledge about the occurrence as well as the understanding of controlling processes of deep groundwater systems is important in order to guarantee their sustainable long-term use. Deep groundwaters have unique chemical and physical properties. Besides higher temperatures, they are often characterised by higher salinities. Higher temperatures as well as higher salinities may potentially cause problems during geotechnical applications. At least handling of deep groundwaters necessitates specific efforts and expenses, e.g. to prevent scaling and corrosion of technical components. While chemical compositions may vary even within one hydro-stratigraphical unit, profound knowledge of groundwater dynamics, regionally dominating forces and processes as well as hydraulic properties is often limited. Hence, predictions of geotechnical use potentials of deep groundwater systems at individual sites are complex and often unreliable. We specifically, but not only, call for contributions that deal with collecting and analyzing data of deep groundwaters and/or use numerical models to consolidate the understanding of the chemistry as well as the dynamics, driving forces and dominating processes in the deep subsurface. We also encourage submissions that specifically address the unknowns and discuss innovative options for the future.