Laboratory and Numerical Modeling of Sea Water Intrusion and Retreat in Coastal Systems

Interaction between sea and coastal systems has been widely analyzed during the past. Approaches to handle the interaction related problems differ depending on the available capacity, starting with sharp interface analytical solutions of the seawater interface within the coastal aquifer. Numerical models are shown to be very robust and time effective tools to mimic the sea water intrusion in coastal systems. Further development of monitoring technology and laboratory infrastructure enabled the conductance of laboratory modeling branch which has shown to be reliable to mimic natural processes at different scales. In this work we present extensive study on the sea water intrusion (SWI) and retreat (SWR) when modeled in laboratory. For this purpose a special infrastructure has been developed and implemented to enable the control of boundary and initial conditions, and to mimic conditions found at coastal aquifer systems. Prior the laboratory experiments, extensive analyses have been conducted to select appropriate color dye and porous media and to determine parameters controlling the SWI and SWR. Results of laboratory experiments emphasize: i) the insight to loadings influencing SWI and SWR, ii) different time scales characterizing SWI and SWR, iii) the influence of head diffrence between the seaward and fresh water boundary conditions and iv) influence of seawater density to SWI and SWR transient features. Numerical model was initially calibrated with experimental results. Furthermore, set of experiments have been modeled to determine its effectiveness and capacity in dual density coupled flow and transport modeling which lead to several key issues: i) features of transition zone as obtained from numerical model differ from experimentally obtained one, ii) numerically obtained results of toe length, cline shape and size as well as its dynamics when reflecting both SWI and SWR show capacity to mimic experimentally obtained results.