To estimate water balance of Pyosun watershed in Jeju Island, a three-dimensional finite difference model MODFLOW was applied. Moreover, the accuracy of groundwater flow modeling was evaluated through the comparison of the recharge rate by flow modeling and the existing one from water balance model. The modeling result under the steady-state condition indicates that groundwater flow direction was from Mt. Halla to the South Sea and groundwater gradient was gradually lowered depending on the elevation. Annual recharge rate by the groundwater flow modeling in Pyosun watershed was calculated to 236 million m3/year and it was found to be very low as compared to the recharge rate 238 million m3/year by the existing water balance model. Therefore, groundwater flow modeling turned out to be useful to estimate the recharge rate in Pyosun watershed and it would be available to make groundwater management policy for watershed in the future.

Abstract
 1. 서 론
 2. 연구방법
  2.1. 연구지역
  2.2. 모의영역 설정 및 입력자료
 3. 지하수 유동 모의
  3.1 정류상태의 모의 결과
  3.2 부정류 상태의 모의 결과
 4. 결론
 REFERENCE

• 송성호(한국농어촌공사 농어촌연구원) | Sung-Ho Song (Rural Research Institute, Korea Rural Research Institute) Corresponding author
• 이규상(한국농어촌공사 농어촌연구원) | Gyu-Sang Lee (Rural Research Institute, Korea Rural Research Institute)
• 안중기(한국농어촌공사 농어촌연구원) | Jung-Gi An (Rural Research Institute, Korea Rural Research Institute)
• 전선금((주) 지오그린21) | Sun-Geum Jeon (Geogreen 21 Ltd.)
• 이명재((주) 지오그린21) | Myung-Jae Yi (Geogreen 21 Ltd.)