An Analysis of the Groundwater Flow s Characteristics Following CLIMATE CHANGES

Abstract

Purpose: The purpose of this study is to estimate the groundwater volume available in the Gyeongju region and predict changes in the groundwater flow s characteristics based on the IPCC RCP climate scenario. Method: As for the method to carry out this study, the results of forecasting the weather conditions in the Gyeongju region based on the IPCC RCP climate change scenario were used. By using the predicted precipitation data, the groundwater volume available was analyzed by using the SWAT MODEL. To analyze the groundwater flow s characteristics, the future groundwater flow s characteristics were analyzed by using MODFLOW by using the observed water level related data. Results: When examining the content by scenario, and across all scenarios, it was analyzed that the M3 basin was the largest, followed by the M2 basin and the M1 basin, respectively. It was also analyzed to be inversely proportional to the size of the outflow hydrologic curve in the case of the M1 basin as the city area was greater than that of the M2 and M3 basins. It was analyzed that the scenario of RCP 2.6 had the lowest variation for the content by basin, and that RCP 4.5 had the largest variation by basin. In terms of the flow direction of the groundwater, the M3 basin flows from the mountainous terrain to the Deokdongcheon Stream along the Deokdong Lake, and the M2 basin flows from the south towards the direction of the Bomun Lake. The M1 basin was analyzed to be the Bukcheon basin and finally flows towards the west side of the Hyeongsan River, and the overall groundwater flow in the target basin was analyzed to flow along the river towards the west side of the Hyeongsan River. Conclusion: As a result of analyzing the groundwater volume available and flow’s characteristics in the Gyeongju region according to climate changes in this study, the amount of groundwater volume available in the future RCP scenario both increased in 2100 compared to the current precipitation. Yet, in the case of RCP 4.5, the duration of no precipitation decreased by 57.75% compared to 2020, and RCP 8.5 increased by 56.79%, and hence, it was analyzed that, as for the available volume in 2100, the RCP 4.5 scenario was calculated to be 6.93% higher than the present, and the RCP 8.5 scenario increased by 0.10% compared to the present. In 2100, when there was no precipitation for 40 or more days, it was analyzed that the groundwater level decreased for RCP 4.5 by 0.7 m on average, and as for RCP 8.5, it was analyzed to decrease by GL by 1.0 m, and hence, the water level’s decrease turned out to be very large for the RCP 8.5 scenario. As a result of the groundwater flow analysis, it was analyzed that it was advantageous for securing the groundwater because of the high groundwater volume available and the groundwater level in the RCP 4.5 scenario where the greenhouse gas reduction policy was significantly realized.