Analysis of the Saltwater Wedge in a Coastal Karst Aquifer with a Double Conduit Network, Numerical Simulations and Sensitivity Analysis

Abstract

We investigate the long-distance salinity in a dual permeability coastal karst aquifer with a double conduit network using a three-dimensional variable-density groundwater flow and multispecies transport SEAWAT model. Sensitivity analyses were used to evaluate the impact of the parameters and boundary conditions on the modeling saltwater wedge in a karstic aquifer situated in the Cuban land territory, including hydraulic conductivity, vertical anisotropy and salinity concentration; both in the conduits network and the fractured medium. These analyses indicated that hydraulic conductivity of the fractured medium and salt concentration were the ones that have a stronger effect on saltwater intrusion in a karstic aquifer. We also show results of the three-dimensional numerical simulations on groundwater salinity for different scenarios with the variabilities of the important parameters and compare results with electric conductivity profiles measured in a well.

Laboratory and numerical investigation of saline intrusion in fractured coastal aquifers

“…Dual porosity modelling is more commonly utilized to simulate saline intrusion in aquifers with existing conduit networks, this bigger discontinuity size permits a more precise determination of the network's position inside the aquifers. In the majority of these investigations, flow is considered Darcian both in the porous medium and in the fractures (Xu et al, 2018;Feo et al, 2019;Kreyns et al, 2020). Nevertheless, multiple numerical approaches have been proposed to incorporate turbulent flow inside the conduits (Arfib and Marsily, 2004;Xu and Hu, 2017;Xu et al, 2019;).…”

Reactive Transport Model of Gypsum Karstification in Physically and Chemically Heterogeneous Fractured Media

“…Implicit fracture representation models include singlecontinuum porous equivalent (SCPE) and dual-continuum porous equivalent (DCPE) models. Fractures are represented by adapting the permeability of the porous medium in the SCPE models [38][39][40][41], while two single-continuum models are linked in the DCPE models to simulate fractured porous media [42][43][44][45][46]. Discrete fracture matrix (DFM) and discrete fracture network (DFN) models constitute two approaches of explicit fracture representation.…”

Groundwater Modelling in Karst Areas

“…Experimental data suggested the presence of a double conduit network that connected the saline water to the inland. In order to understand the whole saline intrusion process, Feo et al [2] developed a simplified numerical model of the investigated aquifer in which the conduit network was modeled as a high hydraulic conductivity layer. Sensitivity analyses were applied to evaluate the impact of the parameters (hydraulic conductivity, vertical anisotropy and salinity concentration) and boundary conditions on the modeling saltwater wedge.…”