H015-09
Modelling seawater intrusion in coastal aquifers under laboratory conditions

Monday, 7 December 2020: 05:54
Virtual
Veljko Srzic1, Ivan Lovrinovic2, Petra Krnic1, Liangchao Zou3, Kresimir Vranjes1, Vladimir Divic4 and Iva Matic1, (1)Faculty of Civil Engineering, Architecture and Geodesy, University of Split, Hydrotechnical Engineering, Split, Croatia, (2)Faculty of Civil Engineering, Architecture and Geodesy, University of Split, Hydromechanics and Hydraulics, Split, Croatia, (3)KTH Royal Institute of Technology, Department of Sustainable development, Environmental science and Engineering, Stockholm, Sweden, (4)Faculty of Civil Engineering, Architecture and Geodesy, University of Split, Head of Laboratory, Split, Croatia
Abstract:
Seawater intrusion has been identified as a dominantly negative process that significantly influences crop productivity in coastal areas. In the literature, many studies focused on this problem and attempted to propose appropriate mitigation measures and verify their effectiveness.

In this work, we aim to study the mechanisms of seawater intrusion using both experimental and numerical approaches. To conduct laboratory experiments, a special flume (3 m length, 0.70 m height and 0.12 m width) has been constructed with glass sides, which enables direct visualization and monitoring for the experiments. The flume is divided into three chambers: i) sea water chamber, ii) freshwater chamber and iii) mid chamber fulfilled with glass beads to mimic porous media. In the experiments, steady state flow processes are imposed by given constant water heads, while initial condition is expressed as C = 0 within the aquifer domain. In addition to the steady state flow conditions, transient flow cases have also been successfully implemented to mimic tidal effects and to study their influences on sea water cline dynamics.

Numerical analysis is conducted by using COMSOL and SEAWAT to simulate the sea water intrusion process and mimic laboratory established conditions. Simulation results cover wide range of hydraulic conductivity values, density effects, in-flow and fixed head boundary conditions, as well as homogeneous and stratified aquifer compositions.

Conclusions from this study are: i) under laboratory conditions, specific attention on the selection of model parameters to mimic density driven processes is needed, ii) numerical simulations by using COMSOL and SEWAT show their capacities to capture the realistic sea water intrusion processes, iii) combination of both experimental and numerical approaches, is shown to be potentially successful way to conduct appropriate calibration and enable us to understand sea water intrusion mechanisms.

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