14. Factors Influencing the Site Selection Criteria for Efficient Aquifer Storage and Recovery (ASR) System in Saline Regions

Groundwater is a vital source of potable water in arid and semi-arid regions, yet groundwater cannot be used in many areas due to increasing groundwater salinity. Aquifer Storage and Recovery (ASR), a managed aquifer recharge technique, is used for excessively available freshwater storage within the saline subsurface for its future recovery. The performance of ASR in the saline aquifer is adversely affected by mixing injected freshwater with ambient saline groundwater. The aquifer hydrogeology and salinity level of ambient groundwater control the mixing phenomena during storage. Therefore, site selection for an ASR scheme in any region needs appropriate aquifer properties to ensure the project's success. This study’s main objective is to determine hydrogeological parameters’ role in the performance of ASR in terms of recovery efficiency using the saturated variable-density flow model (SEAWAT). The model was simulated with varying aquifer properties to optimize different influencing factors. According to the findings of this study, the low hydraulic conductivity and hydraulic gradient in thin aquifers with low longitudinal dispersivity favor ASR performance in salt-affected regions. Transverse dispersivity and aquifer porosity have a minimal and indirect effect on recovery efficiency. This study’s findings will significantly impact the ASR scheme’s site selection procedure and overall performance.