Integration of groundwater flow simulation using groundwater chemistry and groundwater age

Groundwater flow and solute transport simulation were conducted to reproduce borehole investigations in West coastal area of Miura Peninsular, which are total head, salinity, 14C concentration and 4He concentration. Borehole investigations for 500 m depth and literature surveys were used for constructing simulation model. Steady state simulations at present sea level including extensive sensitivity analysis could not reproduce measured value. Unsteady state simulation considering sea level change and uplift could reproduce replacing modern sea water in the Miura Group and remaining fissile sea water in the Hayama Group. Moreover, 1)existing different origin of sea water, 2)upstream in the Hayama Group, 3)influence of fault to local groundwater flow, 4)validity of permeability in the Miura Group and the Hayama Group were confirmed. These were difficult to understand without simulation. From these results, it is useful to understand local groundwater flow using groundwater flow and solute transport simulation considering water chemistry and groundwater age.