IEG 환경지질연구정보센터

10월 25일(목)․지하수학

2007 추계지질과학연합학술대회 초록집 209

Statistical interpretation of groundwater level change in Seoul, Korea: implication to urban groundwater recharge

Kyoung-Ho Kim

․Seong-Taek Yun

․Gi-Tak Chae

․Chae-Man Joo

1

Department of Earth and Environmental Sciences, Korea University, [email protected]

2

Korea Institute of Geoscience and Mineral Resources

A time-series analysis was performed on the daily groundwater level data from 34 monitor- ing wells in bedrock aquifer of Seoul (a capital of South Korea) for three years, to understand the characteristics of groundwater recharge in urban setting which can provide a background of the policy-making for sustainable groundwater management. The cross-correlation func- tion (CCF) between rainfall and groundwater level was used to estimate the lag time of ground- water level change after a rainfall event. Based on the lag time, monitored wells are classified into two groups. The delay time, a lag time of the maximum correlation between rainfall and groundwater level, was very fast (1 to 7 days) in Group I wells (n = 12), while Group II wells (n = 22) showed the long delay time (17 to 58 days). Such variable response of groundwater level change to rainfall was considered to reflect variable capacities of the transmission of hydraulic pressure induced by recharging rainwater rather than the direct response to rainfall recharge. The estimated delay time showed significant correlation with the elevation, depth to groundwater level, and thickness of soil (or alluvium). Compared to Group II wells, Group I wells with the shorter delay times generally had the shallower groundwater level and were preferentially located toward mountainous area. The localities of Group I wells also tended to have thinner soil (or alluvium) cover. On the other hand, ground cover characteristics (i.e., pavement) around wells had no correlation with the delay time. Therefore, the characteristics of groundwater recharge in urban setting are likely controlled by natural conditions such as topography and soil thickness, rather than land use. The present study suggests that natural conditions should be more carefully considered for designating "Groundwater Preservation Area."

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