Comparing traditional and parametric groundwater budget methods to assess recharge in fractured karst aquifers: Insights from the Scirca spring (central Italy)

Abstract This study investigates the strategically significant Scirca spring, located at the foot of the Cucco Mountain karst massif in central Italy. The research aims to compare spring recharge estimates derived from traditional groundwater budget approaches with those obtained through the APLIS parametric method. Both methodologies were applied within a well-defined recharge area, delineated through comprehensive geo-structural and hydrogeological surveys, thereby ensuring a robust framework for analysis. Recharge estimates were calculated using the Thornthwaite–Mather water balance method, which is based on long-term precipitation and temperature data, and a modified APLIS method, which quantifies recharge as a proportion of precipitation based on topography, soil type, lithology, karst features, and the presence of structural lineaments. Results from the modified APLIS method aligned closely with those from the traditional groundwater budget approach, particularly under the assumption of minimal surface runoff within the recharge area. The cross-validation of both methods highlighted their reliability and complementarity in the context of karst environments. Notably, the modified APLIS method proved especially effective in capturing the influence of tectonic structures on recharge, underscoring its potential as a valuable tool for assessing groundwater recharge in fractured and tectonically active aquifers.