Regional groundwater flow dynamics in alpine carbonate aquifers: mechanisms, boundary conditions and impact of climate change

Gravity-driven regional groundwater flow is common in a variety of topographic and hydrogeologic settings. Carbonate aquifers are unarguably one of the most important hydrogeologic systems, as they are very important groundwater resources for drinking water supplies and their deep regions are probably among the most important thermal water resources. They are less well understood, especially with respect to the concept of gravity-driven regional groundwater flow, as the applicability to such systems was previously debated due to their hydrogeologic characteristics associated with a high degree of heterogeneity and anisotropy. Alpine aquifer systems represent a specific hydrogeologic environment that is generally poorly understood because actual observations of hydraulic head in deep wells drilled in alpine zones are rare. In alpine regions such as the Slovenian Julian Alps, the significant elevation difference between the recharge and discharge areas creates a sufficiently large pressure differential to allow warm upwelling water. The main objective of the proposed project is to dive into the very fundamental mechanism of basin-scale gravity-driven groundwater flow in order to develop a suitable approach for its application in the alpine carbonate region. The project will be based on using field methods (hydrogeological mapping, measurements of in situ parameters, groundwater sampling), laboratory methods (measurements of thermal conductivity of rock samples, chemical and isotopic analysis of water, chemical analysis) and physical based modelling based on mathematical models of the physical properties of groundwater flow and heat transport. The project will be accomplished through the implementation of the following activities: state-of-the-art methods for regional groundwater flow with critical evaluation of existing approaches and methods for analysing physical and chemical processes in regional gravity-driven groundwater flow; collection, review and processing of all existing data from previous and ongoing investigations; implementation of a conceptual model for hydrogeological boundary conditions using quantitative methods; numerical simulation of evolved flow regimes at various scales (local, regional) and time-frames (e.g. influence of climate change) to quantify the main components in regional groundwater and the specific effects on the natural recharge and discharge regime; transferability and applicability of the developed approach to other similar areas worldwide. The project activities will be carried out in the alpine region of western Slovenia, which is an ideal pilot area for studying gravity-driven regional groundwater flow in alpine carbonate environments. In the Bled aquifer system, the regional groundwater discharge component is mainly determined by contact with hydraulically confined conditions represented by thick and low-permeability Oligocene basin sediments, while the effect of faults is considered less significant. The other site is the Zatolmin thermal spring, which flows into the river Tolminka in the western Julian Alps. On the contrary to the Bled aquifer system, the regional groundwater discharge component here is due to fault effects. My activities in this project will focus on implementing an innovative methodology required to address the diversity of hydrogeologic settings and the range of scales from local to regional combined with the possible effects of climate change on regional groundwater flow patterns and dynamics. The results will contribute to the long-term protection, sustainable management and improvement of the quantity and quality of groundwater resources in the alpine environment. The project will significantly improve our understanding of groundwater systems and their interaction with other subsurface activities, surface waters, and ecosystems.