| Summary: | 碩士 === 國立交通大學 === 土木工程系所 === 102 === In this study, a quasi 3-D groundwater density-dependent mass transport model was developed to investigate the process and the impact of physical properties on depth of seawater intrusion. The mass balance of fluid with the interaction of Darcy’s law in the model and solute mass transport equations are numerically coupled. In addition, the variation of density is assumed as a linear relation of concentration. Furthermore, the horizontal length scale of the computational domain, referring to the natural geometry, is assumed much larger than the vertical length scale. Thus, this study employs the layer concept to divide the three-dimensional solute transport equations into depth averaged (two-dimensional) and vertical variation (one-dimensional) equations.
The three different cases i.e. vertical solute transport, horizontal solute transport , were used to verify the model, and then hydraulic conductivity, amount of fresh water recharge and surface recharge or discharge are respectively investigated by a series of hypothetical scenarios. The simulation results show positive correlations between hydraulic conductivity and intrusion of the distance, and negative correlations between amount of fresh water recharge and intrusion of distance. Surface recharge and discharge will affect free convection. Amount of surface recharge increases with decreasing of distance of intrusion. Surface discharge will lead to salinization of groundwater and aggravate situation of seawater intrusion.
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