Desert Mirage or Man-made Reality?

ASR in the Liwa Desert, Abu Dhabi

Abu Dhabi City can soon boast increasing its drinking water storage capacity from only three to 90 days. How? Tilman Mieseler provides an update on a project that will see desalinated seawater injected back into a groundwater aquifer.

In arid regions where natural surface water and (fresh) groundwater resources are limited, artificial recharge and storage of water in aquifers can play a major role in water resources management. In the Emirate of Abu Dhabi, this issue has become even more important with respect to securing a reliable and sustainable water supply.

In many parts of the world, the principle of artificial groundwater recharge is being applied, where excess surface water from rivers, lakes or collected rainwater is infiltrating into underground. However, the recharge of groundwater with large volumes of desalinated seawater (DSW) is a new approach so far nowhere else conducted at such large scale.

At present, the storage capacity for drinking water in the capital Abu Dhabi City lasts only for two to three days. Nevertheless, an appropriate back-up supply system in case of emergency is still missing.

Hydrogeological settings and relative remoteness of the desert in northern Liwa area offer huge natural storage capacity. Recovery efficiency has been estimated at around 85%.

Therefore, the Government of Abu Dhabi requested the Consortium of Dornier Consulting and the German International Cooperation (GIZ) to carry out a feasibility study to investigate the possibility of artificially recharging existing fresh groundwater resources with DSW in the Liwa area.

The hydrogeological settings and relative remoteness of the desert in northern Liwa area offer huge natural storage capacity and excellent protection of natural and artificially recharged water resources from impacts of the surface. The aquifer already contains a large amount of fresh groundwater, which is still unaffected by domestic and agricultural activities.

Based on the promising results of this feasibility study, the ASR-Pilot Project was operated over one year, successfully demonstrating the efficient artificial recharge of the local aquifer system with DSW and subsequent recovery on a larger scale.

During the pilot plant operation, a total volume of 2.2 million cubic meters of DSW was introduced to the local dune sand aquifer. The ASR-pilot project confirmed the suitability of the aquifer at the chosen location, as well as the functioning of the applied infiltration/abstraction designs.

The consultancy services for the main project "Strategic Artificial Water Storage and Recovery Project (ASR)" were later awarded in 2008 to Dornier Consulting/GIZ. After the detailed design of infrastructure components as well as the preparation and evaluation of tender documents, the construction works started in 2010. The ASR-Project in the Emirate of Abu Dhabi will eventually consist of recharge/recovery schemes each with an infiltration basin surrounded by recovery wells. Data from additional groundwater monitoring wells around the schemes will contribute to the overall monitoring and process control system of the ASR-Plant.

Furthermore, large transmission pipelines, pumping stations and reservoirs are being constructed in the course of this project. Based on the results from the drilling, construction and testing of monitoring and recovery wells, the existing large-scale numerical groundwater model is being updated. The estimated recovery efficiency is around 85%, based on the results from groundwater modeling. The recovered water will be of potable water quality.

After construction and commissioning of the ASR-Plant, during an infiltration period of 27 months, a major strategic freshwater resource will have been created.

This will help ensure the safe water supply for the inhabitants of Abu Dhabi City for a period of at least 90 days. Once implemented, the ASR-Project will represent a benchmark for water resources management in arid regions.

Author's note: Tilman Mieseler is a senior hydrogeologist and project manager at Dornier Consulting based in Abu Dhabi, U.A.E.. For more information, please contact: [email protected]

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