Identifying the recharge processes of karst aquifer in Umbria (Central Italy) using long-term monitoring data and Modkarst Model

Aquifers and karst springs are among the most studied and challenging topics of hydrogeology in recent years. They are difficult to model due to the aquifer's heterogeneity and anisotropy, as well as the difficulties of conventional monitoring. However, they are among the most important groundwater resources, accounting for a significant portion of freshwater intended for human consumption, especially in the EU.

The study area is located in the Umbria Region in central Italy and is characterised by an elongated carbonate ridge formed by a multilayered karstified carbonate succession, locally separated by marly interbeds. Groundwater circulation is controlled by Apennine tectonics, with faults either enhancing or limiting hydraulic connectivity between hydrogeological units. Recharge occurs predominantly through diffuse but also local infiltration over carbonate outcrops and high plains.

This study contributes to the understanding of hydrogeological functioning by integrating long-term monitoring data (more than 20 years) of discharge and rainfall with numerical modelling.

The data reveal that the karst system exhibits highly complex hydrological behaviour, and the distinctive hydrograph shapes observed for certain springs are attributed to direct surface water inputs entering the system through local sinkholes. Modkarst Model that was applied to six major karst springs, allowed the quantification of surface water contribution.

This work highlights that effective management of karst aquifers under increasing climate change effects that usually requires integrated approaches combining geological understanding, continuous monitoring, and modelling.