Assessing the Potential of Groundwater Recharge and Aquifer Storage and Recovery in a Semi-Arid Basin Using Geochemical Tracers and Isotopic Profiling

Project Abstract

In this study, we evaluate the feasibility and performance of groundwater recharge (GWR) and aquifer storage and recovery (ASR) in a semi-arid basin through an integrative approach that combines hydrogeology, geochemical tracers, and isotopic profiling. The semi-arid basin exhibits seasonal rainfall variability, high evapotranspiration, and limited sustained groundwater yields, making strategic recharge and storage critical for water security. Field campaigns were conducted to characterize hydrogeological frameworks, including aquifer transmissivity, storage coefficients, and hydraulic gradients, supplemented by long-term monitoring of groundwater levels, temperature, and electrical conductivity. Geochemical tracers (stable isotopes 18O, 2H, 13C, and noble gases) and ionic signatures (Ca2+, Mg2+, Na+, K+, HCO3?, SO4^2?, Cl?) were integrated with irrigation return flow and rainfall infiltration data to delineate recharge sources, infiltration pathways, and residence times. Isotopic profiling across depth profiles and time series enabled discrimination between natural recharge, incidental recharge from high-intensity rainfall events, and managed recharge through infiltration basins. A geochemical forward model, calibrated with measured tracer concentrations, was used to quantify recharge rates, travel times, and dilution effects within the aquifer system. The study evaluates various ASR scenarios, including seasonal injection of surface water during wet periods and the subsequent withdrawal during dry periods, to optimize storage efficiency and water quality. Results indicate heterogeneous aquifer response influenced by lithology, fracture networks, and stratigraphic layering, with recharge efficiencies ranging from X to Y% depending on aquifer test conditions and basin hydraulics. Isotopic compositions reveal distinct signatures for recharged water compared to native groundwater, enabling robust identification of stored water masses and their mixing with native groundwater over time. Geochemical tracers reveal mineralization processes, redox zonation, and potential water-rock interactions that may affect post-recharge water quality, including shifts in dissolved inorganic carbon, trace metal mobility, and salinity. Sensitivity analyses show that infiltration rate, basin geometry, and aquifer porosity are primary controls on ASR performance, while climate scenario projections indicate increased variability in recharge opportunities under future conditions. The integrated framework demonstrates a decision-support tool for water managers to assess GWR feasibility, optimize recharge timing, and monitor aquifer health during ASR operations. Recommendations include adaptive recharge design to minimize contaminant intrusion, incorporation of continuous isotopic monitoring for real-time tracking of stored water, and regular water quality assessments to mitigate geochemical risks. This work contributes to advancing quantitative estimates of recharge and storage capacities in semi-arid settings, offering transferable methodologies for evaluating ASR viability in similar basins worldwide, and highlighting the critical role of geochemical and isotopic tracers in validating groundwater management strategies.

Project Overview

What This Project Is About

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A straightforward study of how groundwater can be recharged in a dry area and how the stored water can be recovered later. It looks at the ways to bring water into underground layers, check if that water stays clean, and track where it comes from using simple tools that scientists use to read water’s history.

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The Problem It Addresses

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In semi-arid regions, water shortages limit farming, drinking supply, and ecosystems. Traditional methods may not keep up with demand or protect water quality. The project investigates safer, more reliable ways to add water to aquifers (underground reservoirs) and retrieve it when needed, while keeping an eye on possible contamination and efficiency.

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Objectives of the Project

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1. Understand the basics of groundwater recharge and aquifer storage and recovery (ASR).
2. Learn how geochemical tracers and simple isotopic clues can tell water’s source and travel.
3. Evaluate how well recharge methods work for a specific semi-arid area.
4. Identify potential risks to water quality and how to mitigate them.
5. Propose practical guidelines for sustainable ASR in the study area.

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What You Will Do Step by Step

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Review background literature; select a study site; collect water samples from surface and groundwater; test basic chemical makeup and isotopic signatures; compare results to determine recharge effectiveness; assess storage and recovery performance; discuss implications for water management.

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Expected Outcome

A clear assessment of how feasible and safe groundwater recharge and recovery are in the chosen basin, with simple recommendations for operators and policymakers to improve water security and protect water quality.