Abstract
To interpret the groundwater regime in impermeable rocks, stable isotopic analyses have been done on pore waters collected from the abstraction of the drilled cores. The stable Oxygen and Hydrogen isotopes and EC data show that the origin of porewaters in the study area would be divided into three groups; present precipitation, paleo precipitation and fossil seawater.
The effecting depth of paleo precipitation is about 400m below the sea level, while present precipitation is infiltrated only down to 160m. It is considered that the difference of the sea level between glacial and inter glacial period caused the diversity of groundwater activities.
