A numerical study of saline contamination of a coastal aquifer

A three-dimensional mathematical model of variable density groundwater flow and miscible solute transport is developed to investigate the saltwater contamination of a coastal aquifer in west Japan. The selected area is an agricultural region located on a coastal aquifer where the groundwater is being consumed continuously as the main water source for drinking, greenhouses and industries. The salinity of the pumped water has been analysed periodically and it has been found that the threat of saltwater intrusion is emerging due to the continuous exploitation of groundwater. Owing to the distributed nature of pumping-well locations and nonuniform geological conditions, a three-dimensional model is needed to understand the saline contamination of the coastal aquifer. A numerical model was built by using the finite difference framework, taking into account the development of a transition zone and the variation of fluid density within it. The model simulates the saturated and unsaturated zone groundwater flow under the influence of a variable density situation in the coastal aquifer. Moreover, it can be used as a numerical tool to simulate the salinity contamination of the freshwater in this coastal aquifer.