Impacts of pumping on the spatiotemporal dynamics of a fresh-saline water mixing zone in a coastal lagoon-aquifer system

Abstract

Study region: The Songjiho coastal lagoon, located in the Gangwon Province, Korea, has a unique geographic setting surrounded by mountains and the ocean. Its distinctive hydrological configuration consists of two smaller sub-lakes interconnected by a narrow channel. Its hydrodynamics is significantly influenced by an inlet and outlet, which are connected to the inflowing stream and tidal current, respectively. Study focus: We examined the effect of pumping on the spatiotemporal dynamics of the fresh-saline water mixing zone (FSM) to gain insights into the underlying response mechanisms by pumping. We conducted a series of systematic pumping tests at three fully screened wells installed in the lagoon-aquifer. We monitored electrical conductivity and water temperature with depth. Additionally, we collected and analyzed comprehensive sets of relevant hydrogeological field data. New hydrological insights for the region: Our investigation has pinpointed the dispersion resulting from the concentration gradient as a primary governing factor of the behavior of the FSM. Furthermore, the results also underscore the crucial relationship between the permeability of the layers and the mixing process, which is affected by the inherent heterogeneities in the geological structure and hydraulic properties of the aquifer. In light of these findings, we propose a conceptual model that comprehensively represents the spatiotemporal variations of the coastal lagoon-aquifer system. The model will serve as a valuable tool for understanding and predicting the complex interplay of factors that influence the behavior of this complex hydrogeological system.

Keywords

• Fresh-saline water interface
• Pumping test
• Mixing process
• Hydrogeologic characterization
• Electrical conductivity
• Coastal aquifer