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Seismic waves caused by earthquakes can lead to the movement of fresh groundwater and saltwater in coastal aquifers. The groundwater level, temperature, and electrical conductivity in coastal monitoring wells on the volcanic island of Jeju all responded to the 2011 M 9.0 Tohoku-Oki earthquake. As a result of the earthquake, groundwater temperature and electrical conductivity patterns demonstrated freshwater outflow and saltwater inflow through the monitoring wells in multi-layered coastal aquifers. The seismicity also affected the behavior of ocean tides occurring at depth along the multi-layered coastal aquifers. These observations prove that the use of multi-depth systems for monitoring groundwater level, temperature, and electrical conductivity are more effective than single monitoring systems for understanding the exact behavior of multi-layered aquifers as well as efficiently detecting earthquake-induced or anthropogenic impacts on aquifers in coastal, karstic, or volcanic areas.
Byeongho Won; Se-Yeong Hamm; Kue-Young Kim; Kyoochul Ha; Jehyun Shin; Seho Hwang; Soo-Hyoung Lee. Response Analysis of Multi-Layered Volcanic Aquifers in Jeju Island to the 2011 M9.0 Tohoku-Oki Earthquake. Water 2019, 11, 942 .
AMA StyleByeongho Won, Se-Yeong Hamm, Kue-Young Kim, Kyoochul Ha, Jehyun Shin, Seho Hwang, Soo-Hyoung Lee. Response Analysis of Multi-Layered Volcanic Aquifers in Jeju Island to the 2011 M9.0 Tohoku-Oki Earthquake. Water. 2019; 11 (5):942.
Chicago/Turabian StyleByeongho Won; Se-Yeong Hamm; Kue-Young Kim; Kyoochul Ha; Jehyun Shin; Seho Hwang; Soo-Hyoung Lee. 2019. "Response Analysis of Multi-Layered Volcanic Aquifers in Jeju Island to the 2011 M9.0 Tohoku-Oki Earthquake." Water 11, no. 5: 942.
This study showed the hydrogeological characteristics of an alluvial aquifer that is composed of sand, silt, and clay layers in a small domain. It can be classified into a lower high-salinity layer and an upper freshwater layer and contains shells and remnant paleo-seawater (average 5000 μS/cm) due to sea level fluctuation. Geological and electrical conductivity logging, a long-term pumping test, and multi-depth water quality measurements were conducted at pumping, injection, and observational wells to evaluate the hydrogeologic properties, identify the optimal recharge rate, and assess artificial recharge. Using a hydraulic test, a large difference in drawdown and salinity appeared at the radially located observational wells because of the difference in hydraulic connectivity between the wells in the small study area. It was concluded that the hydraulic anisotropy and heterogeneity of the alluvial aquifer should be carefully examined when locating an injection well and considering the efficient design of artificial recharge.
Soo-Hyoung Lee; Se-Yeong Hamm; Kyoochul Ha; Yongcheol Kim; Dong-Chan Koh; Heesung Yoon; Sung-Wook Kim. Hydrogeologic and Paleo-Geographic Characteristics of Riverside Alluvium at an Artificial Recharge Site in Korea. Water 2018, 10, 835 .
AMA StyleSoo-Hyoung Lee, Se-Yeong Hamm, Kyoochul Ha, Yongcheol Kim, Dong-Chan Koh, Heesung Yoon, Sung-Wook Kim. Hydrogeologic and Paleo-Geographic Characteristics of Riverside Alluvium at an Artificial Recharge Site in Korea. Water. 2018; 10 (7):835.
Chicago/Turabian StyleSoo-Hyoung Lee; Se-Yeong Hamm; Kyoochul Ha; Yongcheol Kim; Dong-Chan Koh; Heesung Yoon; Sung-Wook Kim. 2018. "Hydrogeologic and Paleo-Geographic Characteristics of Riverside Alluvium at an Artificial Recharge Site in Korea." Water 10, no. 7: 835.
Time series models based on an artificial neural network (ANN) and support vector machine (SVM) were designed to predict the temporal variation of the upper and lower freshwater-saltwater interface level (FSL) at a groundwater observatory on Jeju Island, South Korea. Input variables included past measurement data of tide level (T), rainfall (R), groundwater level (G) and interface level (F). The T-R-G-F type ANN and SVM models were selected as the best performance model for the direct prediction of the upper and lower FSL, respectively. The recursive prediction ability of the T-R-G type SVM model was best for both upper and lower FSL. The average values of the performance criteria and the analysis of error ratio of recursive prediction to direct prediction (RP-DP ratio) show that the SVM-based time series model of the FSL prediction is more accurate and stable than the ANN at the study site.
Heesung Yoon; Yongcheol Kim; Kyoochul Ha; Soo-Hyoung Lee; Gee-Pyo Kim. Comparative Evaluation of ANN- and SVM-Time Series Models for Predicting Freshwater-Saltwater Interface Fluctuations. Water 2017, 9, 323 .
AMA StyleHeesung Yoon, Yongcheol Kim, Kyoochul Ha, Soo-Hyoung Lee, Gee-Pyo Kim. Comparative Evaluation of ANN- and SVM-Time Series Models for Predicting Freshwater-Saltwater Interface Fluctuations. Water. 2017; 9 (5):323.
Chicago/Turabian StyleHeesung Yoon; Yongcheol Kim; Kyoochul Ha; Soo-Hyoung Lee; Gee-Pyo Kim. 2017. "Comparative Evaluation of ANN- and SVM-Time Series Models for Predicting Freshwater-Saltwater Interface Fluctuations." Water 9, no. 5: 323.