Saline water intrusion into fresh groundwater aquifer at eastern area, Cheju Island, Korea

摘要

Based upon the groundwater level monitoring results for several years, the Cheju Island can be divided into four regions showing similar variation patterns of the groundwater table. The reason seawater is intruded more deeply into the inland direction in the East region can be summarized as follows; first, the groundwater level is declined by itself during the dry season and also by the excessive pumping due to the increasing water demand in the region; second, it has a favorable secondary geologic structure for the groundwater movement which is formed by the eruption of the Lath-Feldspar-Olivine-Basalt (FOB) of the low viscosity; third, the low permeable unconsolidated sediments (USF) underlying below 100m in elevation can not effectively cut off the saltwater intrusion. These factors cause saltwater intrusion into the fresh groundwater aquifer and have influences on the saltwater intrusion into the deeper part of the inland.