A study on long-term behavior of groundwater flow in coastal aquifer

In order to investigate geological disposal installation of high-level radioactive waste, groundwater flow in wide area has to be estimated in long terms. In Japan, geological disposal installation in coastal aquifer is considered as a feasible plan. In coastal aquifer, groundwater is faced seawater in the end of its flow system. The transient interface of fresh groundwater and salt water is moved by the fluctuation of sea and groundwater level. In this study, a mathematical model, based on the Eulerian-Lagrangian method to solve mass transport problem for density dependent saturated-unsaturated flow, was presented to evaluate the effect of the fluctuation of sea and groundwater level on the long-term behavior of groundwater flow. Also, the relationship between the geological structures and the groundwater flow was investigated based on the model.