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Laboratory experiment on the effectiveness of barrier well on possible freshwater pumping from inland production well
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  • Shinichi Ozaki,
  • Christel Abi Akl,
  • Yuya Fujita,
  • Tatsuya Nagino,
  • Yoshinari Hiroshiro
Shinichi Ozaki
Kyushu University Faculty of Engineering Graduate School of Engineering

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Christel Abi Akl
Kyushu University Faculty of Engineering Graduate School of Engineering
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Yuya Fujita
Oita Prefecture
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Tatsuya Nagino
Kyushu University Faculty of Engineering Graduate School of Engineering
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Yoshinari Hiroshiro
Kyushu University Faculty of Engineering Graduate School of Engineering
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Abstract

Global warming in recent years has been linked to the rising seawater level, resulting in a rise in the level of salt-freshwater interface, which increases groundwater intrusion towards inland. One of the countermeasures for groundwater intrusion is saltwater pumping from a barrier well. In this method, brackish or saline water is continuously pumped through barrier wells near the coast. Many studies on saltwater pumping have focused on the behavior of saltwater intrusion using numerical analysis. However, the quantitative relationship between the production well and barrier well has not been revealed. When using a barrier well in the coastal area, it is important to study the effectiveness of a barrier well against the possible amount of fresh groundwater pumped from an inland production well. If the effectiveness of a barrier well is clarified and saltwater intrusion becomes controllable by water ratio manipulation, it can be implemented in any salinized coastal area to solve salinization problems and fresh groundwater demands. In this study, a lab-scale model simulating a sandy coastal unconfined aquifer was created to investigate the effectiveness of a barrier well. The experiment observed the change in the shape of the salt-freshwater interface and recorded the time required for salinization of a production well and retreat process. Furthermore, the experimental observation quantified the possible freshwater intake ratio between the production well and barrier well. Therefore, saltwater could only reach the production well when the amount of pumped water was more than 1.9 times that from the barrier well. Moreover, by comparing the intrusion and retreat time, the salt-freshwater interface returned to its initial state at a faster rate than the intrusion rate. These findings show that pumping from a barrier well is effective in protecting production wells if the pumping ratios are well controlled.