Delineation of Protection Zones for the Main Discharge Area of the Gran Sasso Aquifer (Central Italy) through an Integrated Geomorphological and Chronological Approach

Abstract

The paper proposes a study for the delineation of protection zones in the main discharge area of the Gran Sasso aquifer (Central Italy). At this aim, starting from a detailed geological and hydrogeological reconstruction, the study was divided into the following phases: 1) development of a conceptual model of water flow in the study area; 2) creation of a 3D numerical model in order to simulate the groundwater flow in saturated conditions, both at the basin and at fine-scale; 3) flow path analysis through deterministic and stochastic approaches; 4) assessment of the aquifer vulnerability based on a geomorphological analysis of the catchment area. Conceptual and numerical models were then used to delineate protection zones for wells and springs with chronological criterion and geomorphological-structural criterion (based on the EPIK method). The results show that with a chronological approach protection zones are located along the main flow directions, corresponding to the areas surrounding wells and springs with high hydraulic conductivity values (faults and thrusts) within the satured zone. On the contrary, the geomorphological method has found some important protection zones also quite far from wells and springs, in areas characterized by quick infiltration processes. The protection zones delineated with the stochastic method were finally intersected by the vulnerability map obtained with the EPIK method, to take into account both filtration and infiltration processes. The results show the local vulnerability of the groundwater to the pollution, with protection zones extending 1 to 5 km towards northeast from springs and wells.