• The Journal of Engineering Geology
• /
• v.30 no.3
• /
• pp.379-397
• /
• 2020

In this study, Long-term change of water quality in Donrae Hot Spring was characterized using water quality data from 1922 to 2019. According to Mann-Kendall analysis and Sen's slope using long-term water quality data of Dongnae Hot Spring from 1922 to 2019, temperature, Ca, SiO₂, and HCO₃ show an increasing trend whereas EC, Na, K, Mg, Cl, and SO₄ show a decreasing trend or negligible trend. In addition, the water type of Dongnae Hot Spring stably belongs to Na-Cl type over time. The spatial distributions of water temperature and chemical constituents in 2004, 2009, 2014, and 2019 show variable patterns with showing some difference depending on sampling locations in different years. These results indicate that despite the long-term pumping of the hot spring water, the water quality is quite stable during the entire study period.

• The Journal of Engineering Geology
• /
• v.14 no.3 s.40
• /
• pp.259-272
• /
• 2004

The purpose of this study is to investigate the effect of hydrochemical variation of groundwater on the gas tigtness in an unlined oil storage cavern. The groundwater chemistry is greatly influenced by the seawater mixing, the water curtain and the dissolution of grounting cements. The chemical composition of groundwater greatly varies ac-cording to both the location of monitoring wells and the sampling period. Most of groundwater shows alkaline pH and high electrical conductivity. The chemical types of groundwater show the dominant order as follows : Na-Cl type > Ca-Cl type > $Ca-HCO_3(CO_3)$ type. Thermodynamic equilibrium state between chemical composition of groundwater and major minerals indicates that carbonate minerals except clay minerals can be precipitated as a secondary mineral. It means that the secondary precipitates can not greatly exerts the clogging effect into fracture aperture in rock mass around oil storage cavern. The content of total organic carbon (TOC) shows a slightly increasing trend from initial stage to late stage. The $EpCO_2$ was computed so as to assess the gas contribution on the $CO_2$ in groundwater. The $EpCO_2$ of 0$\~$41.3 indicates that the contribution of oil gas on $CO_2$ pressure in groundwater system can be neglected.