To properly manage the groundwater resources, it is necessary to analyze the impact of groundwater withdrawal on the groundwater level. In this study, a Long Short-Term Memory (LSTM) network was used to evaluate the groundwater level prediction performance and analyze the impact of the change in the amount of groundwater withdrawal from the pumping wells on the change in the groundwater level in the nearby monitoring wells located in Jeju Island, Korea. The Nash–Sutcliffe efficiency between the observed and simulated groundwater level was over 0.97. Therefore, the groundwater prediction performance of LSTM was remarkably high. If the groundwater level is simulated on the assumption that the future withdrawal amount is reduced by 1/3 of the current groundwater withdrawal, the range of the maximum rise of the groundwater level would be 0.06–0.13 m compared to the current condition. In addition, assuming that no groundwater is taken, the range of the maximum increase in the groundwater level would be 0.11–0.38 m more than the current condition. Therefore, the effect of groundwater withdrawal on the groundwater level in this area was exceedingly small. The method and results can be used to develop new groundwater withdrawal sources for the redistribution of groundwater withdrawals.

This study investigated the temporal-spatial distribution and variations in water quality parameters (temperature, salinity, pH, DO, COD,

The aim of this study was to investigate the accumulation of metallic elements and the control effect of marine pollution caused by ocean dumping in the sediments at a waste disposal area in the Yellow Sea. In July 2009, concentrations of organic matter and metallic elements (Al, Fe, As, Cd, Cr, Co, Hg, Ni, Mn, Pb, and Zn) were measured in surface sediments at the site. The ignition loss (IL) in the surface sediments showed a mean value of 15.4%, about 1.5 times higher than the mean value of the sediments in the coastal areas of Korea. The chemical oxygen demand (COD) at some disposal sites exceeded 20 ㎎ O2/g•dry, which signifies the initial concentration of marine sediment pollutants in Japan. The disposal sites contain higher concentrations of Cr, Cu and Zn than the sediments of bays and estuaries that might be contaminated. The magnitude of both metal enrichment factors (EF) and adverse biological effects suggest that pollution with Cr and Ni occurred due to the dumping of waste in the study area. In addition, the geoaccumulation index (Igeo) showed that the surface sediments were moderately contaminated. By the mid-2000s, when the amount of waste dumped at this site was the highest, the concentration of metallic elements was higher than ever recorded. On the other hand, in 2008-09, the need for environmental management was relatively low compare with the peak. As a result, the quality of marine sediment has been enhanced, considering the effect of waste reduction and natural dilution in the disposal area.