The estimation of groundwater usage in Jeju island is important to understand hydrologic cycle system and to plan management of water resource because large amounts of groundwater have been used for agricultural and domestic purpose. The model has been developed to estimate agricultural groundwater usage for garlic at uplands and citrus at orchards raising outdoors using the soil water balance model from FAO 56, respectively. The total amount of water supplied for the crop evapotranspiration and the multipurpose function such as sprout promotion can be simulated by the model. However, due to the discrepancy of water use in initial stage between calculated and observed, the model was calibrated and verified using actual groundwater usage monitoring data for 3.5 years (2011.6 to 2014.12) at three uplands for garlic and three orchards for citrus. Consequently, it would be concluded that the model simulated efficiently actual water usage in that root mean square (RMS) and normalized RMS of the validation stage were less than 8.99 mm and 2.43%, respectively, in two different conditions.

Abstract
 1. 서 론
 2. 이론적 배경
 3. 자료 및 매개변수 적용
  3.1. 지하수 이용량 및 기상자료
  3.2. 매개변수 적용
 4. 결 과
  4.1. 마늘의 이용량
  4.2. 노지감귤 이용량
  4.3. 고 찰
 5. 결 론
 REFERENCE

• 안중기(한국농어촌공사 농어촌연구원) | Jung-Gi An (Rural Research Institute, Korea Rural Community Corporation) Corresponding author
• 송성호(한국농어촌공사 농어촌연구원) | Sung-Ho Song (Rural Research Institute, Korea Rural Community Corporation)
• 이동림(한국농어촌공사 제주지역본부) | Dong-Rim Lee (Jeju Regional Headquarters, Korea Rural Community Corporation)