Experimental investigation to check the feasibility of an under-surface barrier for stratified layers to remediate seawater intrusion considering an inclined boundary

Abstract

Passive seawater intrusion is recorded due to geological heterogeneity, such as stratification of aquifers. The purpose of this study is to check the performance of a new kind of barrier system for stratified layers with different permeabilities under the influence of an inclined ocean-aquifer interface. The value of permeability ranges from 0.165–0.457 cm/sec. A base case of homogenous aquifer was used to check the feasibility of the glass box model. Coarser material was employed to validate the results with literature by showing similar wedge formation with faster intrusion that reaches the boundary. Toe length to height ratio was in the range of 2.0 to 3.14. Longitudinal dispersion of 1 cm, transverse dispersion of 0.1 cm, and Péclet number of 1.5 were calculated, which falls under the range defined in literature. Results show that the under-surface barrier is much more successful in stopping intrusion when materials with monotonically increasing permeability are considered, as the toe length increases with increasing permeability. For perpendicular stratification, the use of conventional barrier is much less efficient as compared to an under-surface barrier as the toe length to height ratio decreases. Height of intrusion after using an under-surface barrier in different layers decreases subsequently as compared to without the barrier. Application of these results to real-life problems considering factors such as scaling, heterogeneity, applicability of boundary conditions, and temporal dynamics is suggested. Under-surface barriers have merits like ease of installation, fewer complications, etc. Results exhibit that the use of an under-surface barrier starting from the point where the equilibrium of water has reached and extending towards the impermeable strata is the most efficient approach to follow. Sensitivity analysis to check the behavior of saltwater intrusion under various height openings shows that the toe length is affected by the presence of material with higher permeability.