Prediction of Groundwater Sustainability under different climate change scenarios in Pyoseon Watershed of Jeju Island, South Korea

In this studay, we assessed the change of groundwater recharge rate under different climate change scenario (RCP 4.5, 8.5) and predicted the sustainability of groundwater resource in Pyoseon watershed, Jeju Island. For the prediction, the changes in groundwater recharge rate, runoff and evaotranspiration of the study area were estimated using the Soil Water Balance model. The calculated groundwater recharge rate was used for groundwater flow simulation to predict groundwater level change using a numerical simulation program (FEFLOW 6.1). The results showed that the average groundwater recharge rate from 2020 to 2100 was predicted to decrease by 10 12% compared to the current situation (1990 2015) while the evapotranspiration and the direct runoff rate would increase at both climate scenarios. The decrease in groundwater recharge rate due to the climate change results in the decline of groundwater level. The decrease in groundwater recharge resulted in groundwater level drawdown in some monitoring wells, reaching up to 70 m compared to current situation. The model also predicted that seasonal and annual fluctuation of groundwater recharge, runoff and evapotranspiration would be more intensive with climate change, making the sustainable management of water resource more challenging in the future. Our study results demonstrate that the future availability of water resources is highly dependent on climate change. Accordingly, long-term groundwater resource management plan should be established based on the sufficient data, advanced climate change scenarios, and improved modeling methodology.