In a literature review of the recent advancements in mathematical hydrologic models applied in fractured karstic formations, we highlight the necessary improvements in the fluid dynamic equations that are commonly applied to the flow in a discrete fracture network (DFN) via channel network models. Fluid flow and pollutant transport modeling in karst aquifers should consider the simultaneous occurrence of laminar, nonlaminar, and turbulent fluxes in the fractures rather than the laminar flow by the cubic law that has been widely applied in the scientific literature. Some simulations show overestimations up to 75% of the groundwater velocity when non‐laminar flows are neglected. Moreover, further model development is needed to address the issues of tortuosity of preferential saturated fluid flow in fractures suggesting adjustments of the size of the mean aperture in DFN models. During the past decade, DFN mathematical models have been significantly developed aimed at relating the three‐dimensional structure of interconnected fractures within rocky systems to the specific fracture properties measurable on the rock outcrops with the use of reliefs, tracer/pumping tests, and geotechnical field surveys. The capabilities and limitations of previous reported hydrological models together with specific research advancements and findings in modeling equations are described herein. New software is needed for creating three‐dimensional contour maps in fractured aquifers corresponding to the outputs of particle tracking simulations. Existing software based on the equivalent continuum or multiple‐interacting continua cannot delineate the spread of pollutant migrations affected by the tortuous preferential flow pathways that occur in DFNs.

Aquifer over-exploitation may increase coastal seawater intrusion by reducing freshwater availability. Fractured subsurface formations commonly host important freshwater reservoirs along sea coasts. These water resources are particularly vulnerable to the contamination due to seawater infiltration occurring through rapid pathways via fractures. Modeling of density driven fluid flow in fractured aquifers is complex, as their hydrodynamics are controlled by interactions between preferential flow pathways, 3D interconnected fractures and rock-matrix porosity distribution. Moreover, physical heterogeneities produce highly localized water infiltrations that make the modeling of saltwater transport in such aquifers very challenging. The new approach described in this work provides a reliable hydrogeological model suitable to reproduce local advancements of the freshwater/saltwater wedge in coastal aquifers. The proposed model use flow simulation results to estimate water salinities in groundwater at a specific depth (1 m) below water table by means of positions of the Ghyben-Herzberg saltwater/freshwater sharp interface along the coast. Measurements of salinity in 25 boreholes (i.e., salinity profiles) have been used for the model calibration. The results provide the groundwater salinity map in freshwater/saltwater transition coastal zones of the Bari (Southern Italy) fractured aquifer. Non-invasive geophysical measurements in groundwater, particularly into vertical 2D vertical cross-sections, were carried out by using the electrical resistivity tomography (ERT) in order to validate the model results. The presented integrated approach is very easy to apply and gives very realistic salinity maps in heterogeneous aquifers, without simulating density driven water flow in fractures.