Byoung-Woo Yum, KIGAM (Republic of Korea)
Ki-Hwa Park, KIGAM (Republic of Korea)
Dong-Chan Koh, KIGAM (Republic of Korea)
Yongje Kim, KIGAM (Republic of Korea)
Many works on geologic and hydrogeologic settings have been done continuously for solving water supply problems in Jeju Island. Water supply is absolutely dependent on precipitation and ground water, and it is needed to provide enough drinking, domestic and industrial water. KIGAM started the recent geologic and hydrogeologic researches with Jeju Special Provincial Government since 2004. Local Government and KIGAM spent over a million US$ every year respectively.
Ground-water resources in Jeju Island are divided generally into three types: basal ground water, para-basal ground water and upper one (perched one). Autobreccia and/or aa lava are major aquifer-type rocks in it. Large amounts of ground water are found in clinker formations when fine rocks and impermeable and/or low permeable rocks are located beneath it. It is very important therefore to figure the distribution of impermeable and/or low permeable rocks out, which indicates big reservoirs of ground water. Hard and fine rocks, tuff rings and tuff cones, and U-formation are the major target to evaluate the reservoir boundary in Jeju Island, because they are the major rocks with low permeability. KIGAM is building the whole 3-D geologic profiles and distribution maps from 1,500 drilling well data, and these geological setting controls ground-water flow. It is very unique and basic method to prove ground-water flow and reservoir. Recent works of geology and groundwater management in the Island are focused on this article. Jeju Volcanic Island and Lava Tubes was also dedicated as "UNESCO World Heritage", and the main areas are Mt. Halla's Natural Reserve, Geomunoreum lava tube system, and Seongsan Ilchulbong Tuff cone.