Investigation of the Effective Extraction of Fluid in the Fresh Groundwater Lens based on the Three-Dimensional Numerical Simulation

Fresh water lenses are important water resources on oceanic islands. In this research, we examine the effective acquisition method of the fresh water by three-dimensional numerical simulation. Salt water just below the fresh-salt water interface is drawn into the fresh water well by pumping up fresh water. Then fresh water has yet sufficiently remained in the fresh water lens. In considering the effective water intake, the double pumping and water interception board methods were tried. In the model case of circular symmetry topography, the usefulness of the perpendicular double pumping method was confirmed. Seawater pumping amount of 2-4 times of fresh water pumping amount is necessary to obtain low-concentrated fresh water.