<p>Utilizing physical barriers is the most common approach to follow in remediating SWI in coastal aquifers. Implementing a physical barrier in a highly heterogeneous layered aquifer with an oblique boundary is a challenge altogether. The purpose of this study is to determine the effectiveness of mixed barriers and under-surface barriers in a stratified aquifer where the permeable nature of layers increases monotonically. To accomplish this objective, key parameters such as contamination area, toe length, and <i>R</i>^<i>2</i>-value were analyzed in parallel and perpendicular stratification. In parallel layering under-surface barrier outperformed the mixed barrier by reducing the overall contamination by 63.36% as compared to base case by redirecting the intrusion towards low permeable layers. In perpendicular layers, mixed barrier performed slightly better than under-surface barrier and saved 17.14% of groundwater from potential contamination. Parameters such as intrusion profiles, saltwater intrusion rates, and toe length/height fraction were utilized in impact assessment and it was concluded that layers corresponding to average permeability of porous media are much more sensitive towards intrusion fronts through oblique boundary. Also, layer-wise analysis shows that higher intrusion rates correspond to faster and more intense intrusion, while diluted flow is accorded with low intrusion rates. It is concluded that the under-surface barrier has potential to control SWI and works even more effectively than mixed barrier. The study is limited to the use of vertically aligned barriers, monotonic permeable layers, and long-term sustainable performance of barriers. Lastly, to maximize efficiency, physical barriers should be optimized to consider real-world stratification, boundary interactions, and localized intrusion.</p>