Studying the dynamics of the regional groundwater flow system from recharge areas to the discharge zones is probably the most efficient way to answer some fundamental hydrogeological questions, namely: What is the geometry of the groundwater circulation system; where are the main flow paths; what is the natural temperature distribution in the different geologic formations; and what is the magnitude of the heat flow? If properly addressed, these questions can make an important contribution to the study of groundwater dynamics and ultimately to the planning of the sustainable use of thermal water. In this dissertation we study the hydraulic, geochemical, and geothermal processes in the low-temperature geothermal system with warm springs in the Bled area, in a system with karst-fissured aquifers. Here, thermal water with a temperature of 19 to 23 °C is exploited by thermal springs and two pumping wells. The Bled geothermal system is defined by a number of precise boundary conditions, such as a vertical component of groundwater flow, large relative elevation differences between the recharge area, and the discharge of thermal water and concentrated and rapid discharge of warm water to the surface. Based on field observations in period 2018–2020, laboratory and statistical methods, and mathematical modelling of coupled groundwater flow and heat transfer we determined the configuration of the water table and basin-scale flow patterns, and spatially determined the hydrodynamic and geothermal characteristics of the thermal water outflow. We found that the discharge of thermal water in Bled is a consequence of the emergence of complex flow patterns induced by large elevation differences between the recharge area and the discharge zone, and is also influenced by the heterogeneity and anisotropy of the geological formations and their hydrogeological properties.
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