Brackish groundwater resources in Bahrain: Current exploitation, numerical evaluation and prospect for utilization

The IPCC-AR6 report suggests that the sea-level in the Persian Gulf is expected to rise by 2.1-4.9mm/year by 2100, which is lower than the global projections of 4-14mm/year. However, a central nationwide ground subsidence in Bahrain's low-lying island can aggravate these figures. The island is only 14-kilometers-wide, yet we observe a 7×12-kilometer ground subsidence with vertical rates up to 20mm/year for 2016-2021. To characterize the subsidence, we use the following methods: (i) SBAS-InSAR with 94 and 131 C-band Sentinel-1A orbital radar acquisitions in ascending and descending directions for 2016-2021, respectively, and (ii) Stacking-InSAR with eight L-band ALOS-1-PALSAR acquisitions for 2007-2010 and six ALOS-2-PALSAR-ScanSAR acquisitions for 2016-2021. Although the observed subsidence velocities are non-linear, we estimate a subsidence of up to 1.5-meters by 2100 by extrapolating the average rates. We suggest three causes associated with this subsidence: (i) Exploitation of the Awali oil field, (ii) Local aquifer depletion, and (iii) Subsurface dissolution of anhydrites and chalky-limestones. To assess the potential impact of subsidence on the shoreline, we measure the coastline evolution at three undisturbed beaches on the West-coast from 1985-to-2021, excluding areas that underwent land-reclamation. Using sub-pixel shoreline detection analysis from 308 Sentinel-2 and Landsat (L5, L7, and L8) acquisitions, we observe that the selected shores remain stable. However, observations reveal a shoreline retreat of up to 5m/year on the southwestern coast for 2003-2014. This rate exceeds the modeled rate of 0.85m/year derived solely from local tide gauge sea-level measure. This nationwide subsidence should be considered when forecasting coastal infrastructure-planning in Bahrain. We recommend performing a similar analysis in other lowlying Gulf islands where oil exploitation occurs.

show abstract

“…Fig. 3 shows the structural geology and sequence stratigraphy [48][49][50] for the two cross-sections plotted in Fig. 2.…”

Section: A Geology and Oil Productionmentioning

confidence: 99%

“…In the center of the island, where the Rus Formation outcrops from erosion, the Rus-UER aquifer is under unconfined condition. The Dammam aquifer is also unconfined where the Khobar member outcrops due to erosion [50].…”

Section: B Climate and Hydrogeologymentioning

confidence: 99%