Isotope hydrogeological investigations in the Southern Salzburg Basin, Austria

摘要

Despite its importance as a drinking water supply, the origin of groundwater at the Gamp Wellfield (GBF) in the Southern Salzburg Basin (SSB) is still unclear. A study performed between 2014 and 2016 using stable isotopes and numerical 2D groundwater flow modelling led on one hand, to important insights into groundwater recharge, but on the other hand led to contradictions: The model simulations showing groundwater flow to the GBF from the nearby Salzach river is not possible considering the stable isotopes. Therefore, between 2017 and 2019 another study was performed, including 17 additional monitoring points for stable isotopes. Instead of numerical modelling, the focus was put on a comprehensive understanding of aquifer genesis on the basis of recent literature and applying a modern approach to understand geomorphological development of alpine valleys. Hydraulic, hydro-chemical and physical properties of the groundwater were also considered. A conceptual model is developed from the results which permits a coherent explanation of all properties of the regional aquifers. One of the most interesting results of this conceptual model is a fractionation of stable isotopes governed by dynamic seepage of the Taugl creek.