DELINEATION OF AGRICULTURAL DROUGHT-PRONE ZONES CONSIDERING CLIMATE CHANGE SCENARIOS AND IRRIGATION FACILITIES

Agricultural drought is caused by the soil moisture deficiency in accordance with shortage of irrigation water. Deficient moisture hinders germination and growing progress on plants, which eventually leads low plant populations and a reduction of agricultural yields. If drought-enduring agricultural facilities like huge reservoirs constantly supply irrigation water to farm fields which meet the required soil moisture contents during dried period, agricultural drought would not occur. This study was conducted to delineate agricultural drought-prone zones of one representative watershed in South Korea considering the representative concentration pathways (RCPs) as the latest generation of climate change scenario and irrigation capacity of agricultural facilities. The watershed consisted of 51 administrative towns, involving 17 agricultural irrigation facilities (7 reservoirs, 1 pumping station, 8 diversion weirs, and 1 collecting drain). Two sub-scenarios of RCPs, intermediate-level greenhouse gases emission scenario (RCP 4.5) and high-level one (RCP 8.5), were applied to two selective drought indices (standardized precipitation index (SPI) and Palmer drought severe index (PDSI)) in order to identify anticipating drought events in the watershed. Simulated temporal (2014-2055) data of rainfall and temperature for two RCPs with a horizontal resolution 1 km were used as input data for analyzing two drought indices. Results from two indices demonstrated that dried periods more than three consecutive months in rice planting season would be expected on three separate years (2018, 2051, and 2054) for RCP 4.5 and four ones (2029, 2034, 2036, and 2042) for RCP 8.5. A total of 21 administrative towns (53%) in the watershed would be under concerns from drought during these periods of time. With consideration of water capacity of agricultural facilities, 16 towns would be possibly irrigated by the agricultural facilities. Meanwhile, remaining 11 towns were vulnerable to the drought due to lack of water irrigation from facilities. In these towns, additional development of agricultural groundwater wells is required by way of precaution against drought events. In addition, regular dredging of reservoir bottom would be needed for securing more agricultural water and distributing it over more towns.