Strategic subsurface water banking in deep Arabian aquifers

Applications are invited for a self-funded, 3 year full-time or 6 year part-time PhD project.

This PhD will be based in the School of Environment and Life Sciences and will be supervised by Dr Mo Hoque (SELS), and Dr Shamsuddin Shahid (National Center for Meteorology, Saudi Arabia).

Background and Strategic Context

Hyper-arid countries across the Arabian Peninsula have historically relied heavily on non-renewable groundwater stored within extensive sedimentary aquifer systems. Decades of abstraction, particularly for agriculture, have lowered groundwater heads in several major aquifers and increased concern about long-term water security. Surface storage is also constrained by high evaporation and, in some recharge dams and reservoirs, by sedimentation and declining infiltration capacity. These conditions have increased interest in Managed Aquifer Recharge (MAR) and Aquifer Storage and Recovery (ASR) as ways of storing water underground with much lower evaporative loss.

Regional experience shows that strategic subsurface storage is technically possible, but the hydrogeological setting strongly controls performance. The United Arab Emirates (UAE) has developed large-scale storage of desalinated water in the Liwa dune aquifer for emergency supply, while MAR using treated wastewater, stormwater and other sources has been examined or implemented elsewhere in the Gulf. ASR has more commonly been developed for seasonal balancing, shorter storage-and-recovery cycles, or emergency reserves than for deliberate multi-year to decadal water banking. Yet longer-term subsurface storage could become increasingly valuable where water availability is variable, drought risk is increasing, or surplus desalinated or treated water can be stored during periods of lower demand. Most established Gulf schemes also concern shallow or relatively permeable aquifers. The feasibility of retaining recoverable water for much longer periods within deeper, brackish regional aquifers therefore remains much less certain.

A central difficulty is the density contrast between relatively fresh injectate and native brackish groundwater. Lower-density injected water can rise within the aquifer, producing buoyancy-driven segregation, plume tilting and enhanced mixing. Over multi-year storage, ambient hydraulic gradients, aquifer heterogeneity and dispersion can further displace and salinise the stored water, reducing the fraction that can be recovered at the required quality. Water-rock interaction may also cause mineral scaling, ion exchange or mobilisation of fines, affecting well performance and formation permeability.

This project will test whether two controls can improve long-duration storage performance. First, partial salinity matching or other feedwater conditioning may reduce density-driven segregation. Second, stratigraphically or structurally compartmentalised parts of an aquifer may restrict plume migration if they combine sufficient storage and transmissivity with low hydraulic connectivity across their boundaries. Rather than assuming that such 'pockets' provide secure storage, the PhD will examine the geological and hydraulic conditions under which compartmentalisation is beneficial, ineffective or operationally impractical.

Project Aims

The overarching aim is to develop an integrated predictive framework for assessing long-duration subsurface water banking in deep fossil aquifer systems of the Arabian Peninsula. Candidate formations may include the Wasia-Biyadh and Saq sandstone systems or hydrogeologically comparable regional units, depending on data availability and the selected national case study.
The research will first establish plausible geological architecture, hydraulic-property ranges, groundwater salinity and regional boundary conditions from published information and available national or site-specific datasets. MODFLOW 6 will then be used to test the combined effects of density contrast, aquifer heterogeneity, ambient flow, storage duration and well configuration on plume behaviour and recovery efficiency. PHREEQC modelling will evaluate geochemical compatibility between candidate feedwaters and formation waters and minerals, including conditions that favour scaling, dissolution or ion exchange.
The modelling will be used to identify combinations of geological setting, salinity management and wellfield design that retain acceptable recoverability over multi-year to decadal storage. Where moderately brackish storage water is considered, the project will also examine its potential role as a protected feedwater reserve for subsequent treatment or desalination rather than assuming direct potable recovery.
The final output will be a transferable decision framework linking hydrogeological setting, controlling density contrast, geochemical compatibility and operational design. It will define where deep strategic water banking is technically promising, where uncertainty remains too large, and what site investigations would be required before field-scale implementation in Saudi Arabia, the UAE, Kuwait, Oman, Qatar, or comparable arid-region settings.

Recommended Further Reading

• Ferguson, G., et al. (2026). Renewability of fossil groundwaters affected by present-day climate conditions. Nature Geoscience, 19, 410–414.
• Rausch, R., & Dirks, H. (2024). A hydrogeological overview of the Upper Mega Aquifer System on the Arabian Platform. Hydrogeology Journal, 32, 621–634.
• Schulz, S., et al. (2017). Improving large-scale groundwater models by considering fossil gradients. Advances in Water Resources, 103, 32–43.
• Ajjur, S. B., & Baalousha, H. M. (2021). A review on implementing managed aquifer recharge in the Middle East and North Africa region: methods, progress and challenges. Water International, 46, 578–604.

Fees and funding

Visit the research subject area page for fees and funding information for this project.

Funding availability: Self-funded PhD students only. 

PhD full-time and part-time courses are eligible for the UK Government Doctoral Loan (UK and EU students only).

Bench fees

Some PhD projects may include additional fees – known as bench fees – for equipment and other consumables, and these will be added to your standard tuition fee. Speak to the supervisory team during your interview about any additional fees you may have to pay. Please note, bench fees are not eligible for discounts and are non-refundable.

How to apply

We’d encourage you to contact Dr Mo Hoque ([email protected]) to discuss your interest before you apply, quoting the project code.

Please note, to be considered for this self-funded PhD opportunity you must quote project code ELS10091027 when applying.