Dynamic Desalination of Intruding Seawater After Construction of Cut-Off Walls in a Coastal Unconfined Aquifer

• DOI: 10.3389/fmars.2022.857807
• Publication Date: 2022-03-30T05:51:49Z
• Authors: Tianyuan Zheng; Mingpeng Gao; Qinpeng Chang; Xilai Zheng; Marc Walther
• Keywords: Saltwater intrusion

Fresh groundwater resources in coastal regions are valuable but deteriorated by seawater intrusion. To prevent deterioration of the fresh resources, a common approach is to build cut-off walls. However, construction walls may trap large amount residual saltwater landward aquifer. This study explored dynamic behavior and desalination process intruding after wall, using numerical model validated against laboratory experiment. Field-scale simulations reveal that fast repulsion proceeds within short period (100-150 days), while retreat wedge rather slow at beginning. because always starts first vertical direction. Meanwhile, area significantly increases downstream wall. The mainly depends on depth hydraulic conductivity time affected location Although deeper wall can enhance removal saltwater, effectiveness notably decrease when exceeds certain value (25 m simulated scenarios). performance degrades dramatically greater than threshold (8×10 -7 m/s cases). A near-complete be achieved three years with optimal designs depth, location,