Reference application: Liwa Strategic Storage, Abu Dhabi (UAE)

SWS solution

Description

The Liwa Strategic Storage ASR site is located in the sand dune area in central Abu Dhabi approximately 25 km north of the Liwa crescent. To create a strategic freshwater reserve for emergency situations, desalinated seawater is infiltrated into the shallow, unconfined quaternary aquifer through three subsurface infiltration basins which are each surrounded by abstraction and monitoring wells arranged in a circular pattern.

The aquifer consists of dune sand underlain by partly consolidated sand (sandstone). Before recharge, the unsaturated zone had a thickness of approximately 45 m (Sathish and Mohamed 2018). The site is situated on or close to the watershed of a natural freshwater lens which was replenished during wetter periods in the Holocene wetter between 9000 and 6000 BP (Wood et al. 2003) and is one of Abu Dhabi’s most important freshwater sources. The freshwater lens is underlain by brackish water; salinity increases with depth to up to 12500 mg/L (Stuyfzand et al. 2017).

The project started with a feasibility study in 2001 that was followed by a pilot study in 2003-2004. During this study the shallow aquifer was recharged with desalinated seawater using injection wells and a subsurface infiltration basin, which performed better than the injection wells and was subsequently chosen for full-scale implementation. Construction of the full-scale application started in 2009 and was completed end of 2016. Large-scale freshwater injection started in May 2015. The project aim is to infiltrate 26,500 m3/d of desalinated water (TDS < 250 mg/L) for 824 d (21.8 Mm3) and to achieve a recovery rate of 170,280 m3/d for 90 d (67 % recovery efficiency) with a TDS level of approximately 400 mg/L (Stuyfzand et al. 2017).

Keywords

ASR, aquifer storage and recovery, desalination, Freshwater storage, Strategic reserves, Abu Dhabi Emirate

URL

https://www.dornier-consulting.com/ref-test-__-pilot-project-combined-artificial-recharge-and-utilization-of-the-groundwater-resource-in-the-liwa-area-abu-dhabi/?lang=de

Key lessons

Modeling results by Stuyfzand et al. (2017) demonstrate that after a storage time of 6 years, the recovered water will very likely comply with UAE drinking water standards – up to a recovery efficiency of 85%. However, after a storage period of 10 years, the “safe” recovery efficiency would drop to 60% - providing only for an emergency supply for 80 d. Upon further recovery, the maximum permissible concentrations will likely be exceeded for Na, As, Cr and F due to mixing with native groundwater.

Water use - End user

Freshwater production

Freshwater storage volume

Duration of storage/recovery cycle

Source of water for infiltration

Post-treatment after recovery/abstraction