Effect of a Negative Hydraulic Barrier near the Coast on Confined Aquifer Dynamics

High Resolution Image Download MS PowerPoint Slide This study evaluated the long-term impact of negative hydraulic barriers, created by saline groundwater (SGW) pumping in confined coastal aquifers, on groundwater dynamics by combining multiyear field monitoring of pumping and nearby observation wells, hydrogeochemical analyses, and 3D numerical modeling. Monitoring data revealed that the fresh saline groundwater interface (FSI) dynamics was primarily governed by SGW pumping regimes. SGW pumping (180–260 m 3 /h) reduced subaquifer salinity (5–10%) over two years in observation wells 100 m inland. Six years of pumping achieved 12% salinity reduction in the pumped water, at a gradually decreasing rate. Geochemical analyses of the pumped water revealed an evolution of individual elements that deviate from trends associated with salinity decrease, specifically, a nonconservative 20% increase in the Ca 2+ /Cl – ratio alongside a 15% decrease in the B/Cl – ratio. Numerical model simulations fitted short-term hydrological observations and provided long-term prediction of the negative hydraulic barrier efficiency, demonstrating that the FSI becomes restrained at the pumping site. These findings validate the negative hydraulic barrier as a viable management strategy for confined coastal aquifers, offering a scalable framework for optimizing negative hydraulic barrier design to facilitate seawater intrusion mitigation and sustainable SGW production with potential downstream industrial applications.