AN ADVANCED TOOL TO DETERMINE AGRICULTURAL GROUNDWATER USAGE USING CROP COEFFICIENT FOR IRRIGATION TO GREENHOUSE FACILITIES

With the development of agricultural technology, it is possible to cultivate crops in winter at the greenhouse facility cultivation complex, and as the crop cultivation period has increased, the use of groundwater has increased. When calculating the amount of groundwater used, the utilization period should be increased according to the cultivation period. As a result, the groundwater use calculated by the conventional method is applied to the annual use period of 270 days for the whole action and 180 days for the answer action, so the value less than the actual groundwater use for the year is inevitably calculated. Therefore, it is necessary to estimate the irrigation water demand for each crop in consideration of the cultivation period when the groundwater use is calculated in the facility cultivation complex that grows the four season crops. The purpose of this study was to calculate monthly cultivation crops and cultivation periods through Gwang-ju Meteorological Agency's climate data in Korea, land cover map, field survey, and residents' survey to estimate the irrigation water demand by crops in the area around Yeoungsan River where facility cultivation complex is concentrated. Based on the results of the calculation of crop evaporation (irrigation water demand) using the crop coefficients presented by the Rural Development Administration and FAO, it was analyzed that irrigation water is 2,114×1000 ㎥/year for rice, 3,353×1,000 ㎥/year for field crops, and 6,649×1,000 ㎥/year for water dropwort. As a result, water dropwort uses irrigation water twice more than field crops. In addition, except for rice, which mainly uses surface water, the difference in usage amount occurred more than twice as compared to the groundwater use calculated by the existing groundwater use method. Therefore, if the facility cultivation complex that grows four seasons of crops is applied to the irrigation water demand calculation method required by the crops rather than the conventional ground water usage calculation method, it will not only calculate the exact amount of water but also establish proper water supply measures and facility maintenance.

This study was supported by Korea Environment Industry & Technology Institute (KEITE) through Water Supply Service Program corresponding to Groundwater Requirement, funded by Korea Ministry of Environment (MOE).

Key words: groundwater usage, irrigation, greenhouse facilities