The impact of climate change on the groundwater system for 8 hydrogeological units were quantitatively evaluated with time-series groundwater level data from 80 monitoring wells for more than 10 years. The evaluation was based on accumulation period (AP) correlated with the standardized precipitation index (SPI) and standardized groundwater level index (SGI). The analysis showed that when the AP of the aquifer is relatively short, the aquifer is considered to be temporarily responsive to short-term droughts but relatively less affected by long-term droughts. On the other hand, if the AP of the aquifer is long, it is estimated that the resilience of the groundwater system decreases in the event of a relatively long drought, and consequently the vulnerability to climate change increases. In conclusion, regardless of the hydrogeological unit, as the AP of the aquifer has increased in recent years, it is estimated that the impact of climate change on the groundwater system is gradually increasing.

Keywords: Climate change, Vulnerability, Groundwater system, Hydrogeological unit, Standardized groundwater level index (SGI)