Characterizing local mountain groundwater systems through spring discharge variability: a case study from the Sudetes

Abstract

This study evaluates whether long-term spring-discharge records can be used to distinguish modes of functioning of local mountain aquifer systems in the Sudetes (SW Poland). Four springs representing three hydrogeological settings were analysed: porous-fractured Cretaceous sedimentary rocks, weathering mantles and fractured crystalline rocks, and weathering mantles developed on volcanogenic rocks. The methodology combined statistical measures of discharge variability, flow duration curves, the Pardé coefficient, autocorrelation and cross-correlation analyses, master recession curves and baseflow index interpretation. The Szczytna spring, draining a sedimentary aquifer system, represents the most stable flow regime, with the highest retention capacity and the greatest resistance to short-term variability in recharge. The Kowary and Różanka springs display intermediate characteristics, typical of shallow groundwater circulation systems developed within weathering mantles and fractures in crystalline rocks. The Kowalowa spring is characterized by the most dynamic response to recharge, high discharge variability, and the fastest depletion of groundwater resources. The obtained results should be regarded as indicative, as the analysis is based on weekly data and does not include independently delineated spring recharge areas. Nevertheless, the study demonstrates that long-term spring discharge records can support a process-based interpretation of retention and drainage in poorly investigated mountainous aquifer systems.