Investigating the influence of geological heterogeneity in the advancement of the saltwater wedge: A novel perspective study employing Experimental, DC Sounding and Numerical modeling approach

The global issue of saltwater intrusion (SWI) is impacting coastal aquifers more prominently due to climate changes and the escalating demand of freshwater for various anthropogenic activities. Consequently, there has been a heightened focus on research in this area to improve predictions regarding the effect of geological media on the advancement of salt water into fresh aquifers. The current study simulated saltwater flow into a freshwater zone for a coastal environment, considering density-dependent effects. Two specific scenarios were considered: one involving homogeneous media and the other involving heterogeneous media. In prior studies, researchers commonly employed homogeneous media exclusively for simulating SWI experiments. However, for the present work, we also incorporated heterogeneous media with a geophysical Direct Current (DC) sounding approach to determine the interface between fresh and saltwater. The experimental responses were numerically modelled to know the behaviour of geological constraints during the flow of saline water. For validation, a field example of the DC resistivity survey was incorporated for a better correlation. The experimental findings suggest that the interface between freshwater and saltwater was influenced when the advancing saltwater wedge encountered the clay layer. For a coastal environment, a clay layer (which is porous but not permeable) is crucial in influencing saltwater intrusion dynamics. The agreement between experimental data, numerical simulations, and DC-sounding outcomes indicates that the proposed integrated approach can be a valuable benchmark for future studies on seawater intrusion, even in environments with more complex geological conditions.

 

Keywords: Aquifers, Saltwater Intrusion (SWI), DC Sounding, Numerical modeling.