Groundwater & Aquifers

Groundwater is the region’s least visible water resource. According to UNESCO and UN-Water, it is the most relied-upon source in at least 11 of the 22 Arab states, a wider grouping than the twenty countries covered here, and it supplies more than 80% of freshwater withdrawals in Libya, Djibouti, Saudi Arabia and Palestine.¹ Unlike a river, nobody can see it. Unlike a reservoir, nobody can easily measure what is left.

The satellite record puts hard numbers on the decline. NASA’s GRACE mission measured 143.6 km³ of fresh water lost across the Tigris and Euphrates basin and western Iran in the seven years from 2003 to 2009, nearly a Dead Sea’s worth. Roughly two-thirds of it, 91.3 ± 10.9 km³, came out of groundwater, at 17.3 ± 2.1 mm a year of equivalent water height against a total storage loss of 27.2 ± 0.6 mm a year.² It remains the clearest single measurement of a region spending its buffer.

Much of this water is not renewable on any human timeframe. The Nubian sandstone was filled in the Pleistocene, and its recharge today is described as effectively zero, so pumping it is closer to mining than to harvesting.³ Saudi fossil water in the north is about 20,000 years old, and rainfall of 100 to 200 mm a year does not replace it.⁴ For the Gulf states as a group, depletion of non-renewable groundwater has been estimated at 317% of the renewable volume.¹

In many places the renewable aquifers, the coastal and alluvial systems, are drawn down faster than rainfall replaces them, which pulls seawater inland and pushes salinity up.¹ Richey et al. (2015) name the Arabian Aquifer System and the Murzuk-Djado Basin as the most overstressed of the 37 large aquifers on their GRACE-based measure; the Nubian and North Western Sahara systems are also overstressed.⁵

For companies and lenders, this is a market defined by measurement and remediation. It covers drilling and well-field rehabilitation, monitoring and metering, managed recharge, brackish desalination, and the modelling work behind abstraction licences and transboundary negotiations.

Four systems dominate the map. The Nubian Sandstone Aquifer System, among the largest bodies of fresh water on earth, underlies Egypt, Libya, Sudan and Chad and feeds Libya’s Great Man-Made River.^6 7 The North Western Sahara Aquifer System, NWSAS in English and SASS in the French literature, is shared by Algeria, Tunisia and Libya.⁷ The Saq-Ram aquifer system, also known as Disi, runs under Saudi Arabia and Jordan and supplies Amman through a 325 km conveyor.^8 9 The Umm er Radhuma and Dammam limestones stretch beneath most of the Gulf peninsula, and the regional inventory maps them as three separate sections rather than one.^10 11 12

The systems, and what is known about them

The region’s major aquifer systems, largest first. Where the regional inventory and IGRAC delineate the same system differently, both figures are shown.

The four systems, and the state of each

Nubian Sandstone: the largest, and the one being spent

About 540,000 km³ of water is thought to be stored, of which some 15,340 km³ is considered exploitable, across an area the Joint Authority puts at 2 million km² and IGRAC delineates at 2.45 million.^6 13 Recharge today is effectively zero.³

Libya’s network is about 4,500 km long and supplies more than 70% of its urban areas. In December 2024 a report said the project was entering its fifth and final phase, described it as a US$7 billion initiative and put its total cost at US$25 billion.¹⁴

Saq-Ram, also known as Disi

Sandstone running under Saudi Arabia and Jordan, supplying Amman through a 325 km conveyance since 2013 at 100 million cubic metres a year from a field of 55 wells, under a 25-year build-operate-transfer concession.^9 15

The asymmetry is the point. Jordan holds 4 to 10 billion cubic metres of the system against Saudi Arabia’s 740 billion, recharge is 2 to 20 mm a year, and Saudi abstraction near Tabuk rose from about 29 million cubic metres a year in 1983 to between 1,050 and 1,700 million by 2004, against recharge of 3 to 10 million.⁸ It is also a bridge rather than a supply, which is why Jordan spent the years it bought building a carrier from the sea.

Umm er Radhuma and Dammam: the Gulf’s shallow reserve, turning brackish

Three mapped sections, not one. The southern section under Oman, Saudi Arabia, the UAE and Yemen covers about 680,000 km²; the central section under Bahrain, Qatar and Saudi Arabia about 281,000; the northern section under Iraq, Kuwait and Saudi Arabia about 246,000, where water levels have fallen by up to 60 metres in both formations.^10 11 12

Average abstraction of 97 million cubic metres a year from the Dammam in Bahrain (2010) and 54.3 million from its Umm er Radhuma (2006), 91 million in Qatar (1983) and about 608 million in Saudi Arabia (2006) has left the central section open to salinisation.¹¹ Seawater intrusion has been reported up to 8 km inland on Oman’s north-west coast.¹⁶ Abu Dhabi stores desalinated water in the Liwa Strategic Water Reserve, in a dune aquifer, which is storage rather than abstraction.¹⁷

North Western Sahara: shared by Algeria, Tunisia and Libya

Over 1 million km², of which 700,000 in Algeria, 80,000 in Tunisia and 250,000 in Libya, recharged by only about 1 billion cubic metres a year.⁷ IGRAC lists the system with two riparians rather than three.¹³

Abstraction rose from 0.6 billion cubic metres a year in 1970 to 2.5 billion in 2000, about two and a half times annual recharge, drawn from roughly 8,800 water points. Agriculture is the major water consumer.⁷

The renewable aquifers, which are the ones actually failing

Coastal and alluvial systems do recharge, but in many places they are drawn down faster than rainfall replaces them. That pulls seawater inland and pushes salinity up.¹

Morocco’s Souss is the clearest measured case: piezometer 859/62 in the upstream Souss fell 1.9 metres a year between 1998 and 2008 and 3.5 metres a year between 2012 and 2020, while the correlation between the rainfall index and the standardised water-level index across the Souss and Massa is 0.07, which points at pumping rather than drought.¹⁸ In Iraq’s Sinjar and Ba’aj districts, where groundwater is the only source, more than 75,000 people in Wardiya, Solagh, Tal Banat and Tal Qasab face shortages, rainfall has fallen 40% in five years and 15% of residents have already migrated.¹⁹

One case in this sector, examined in full.

The hub's headline metric for all twenty countries. Hover, tap or focus a country; the ranked table sits alongside.

Four independent measurement methods now cover the region: satellite gravity for whole aquifers, piezometric records for national totals, radar interferometry for the ground surface, and well logs for individual basins. They agree on direction and differ on magnitude, which is worth saying plainly rather than averaging away.

North Africa, from satellite gravity

Between 2003 and 2016 the Nubian system lost around 50 km³ and the North Western Sahara more than 30 km³. The Nubian loss is attributable to abstraction alone; the North Western Sahara loss is part climate and part abstraction, and the nearby Tindouf basin, which tracks rainfall closely, lost under 10 km³.²⁰ Depletion rates have been put at 6.08 ± 1.9 km³ a year for the Nubian and 2.69 ± 0.8 for the Sahara, against non-satellite estimates of 2.17 km³ for the Nubian, for 2000, and more than 2.2 km³ for the Sahara.²¹

Iran, from well records and radar

Piezometric records across 478 sub-basins give a loss of about 74 km³ between 2002 and 2015, some 5.25 km³ a year, with extreme overdraft across roughly 77% of the land area.²² These are well records, not gravity measurements, so they cannot be added to GRACE totals. A separate radar study puts annual depletion from confined and semiconfined aquifers at about 1.7 billion cubic metres.²³

The ground is following the water down. Sentinel-1 interferometry for 2014 to 2020 makes Rafsanjan the fastest-sinking place in the country at 37 cm a year, ahead of Arzuiyeh at 34, Savojbolagh at 29 and Nazarabad at 27, with subsidence hazard across 56,000 km², 3.5% of Iran, where more than 14 million people live.²³ Mashhad has the longest record and the clearest pairing of cause and effect: a water table down 65 metres over four decades, and vertical deformation of about 19 cm a year.²⁴

Egypt and Saudi Arabia

For Egypt, GRACE gives depletion of 0.64 ± 0.03 cm a year over Sinai and 0.32 ± 0.03 over the Nile Delta aquifer between 2003 and 2021, with about 7.25 km³ taken from the Nubian in the Western Desert. Losses from the Moghra aquifer rose roughly eightfold across the same period, from 32 to 262 million cubic metres a year.²⁵

Saudi Arabia’s total water storage fell 7.94 ± 0.22 mm a year from 2002 to 2016. The Saq is where the methods genuinely conflict: the same study reports a significant negative storage trend over the aquifer and a positive recharge estimate of 4.65 ± 0.10 km³ a year, so no single clean figure for the Saq can responsibly be quoted.²⁶ Storage under the northern desert is put at 252 to 870 km³, and hydrologists expect only about 50 more years of economic pumping, which is why the wheat programme was phased out from 2008 and ended in 2016.⁴

Jordan, Morocco and Yemen, from the basin records

Six of Jordan’s twelve basins were pumped at 146 to 235% of safe yield; Azraq’s four main springs had dried out by 1992, and its water table had fallen about 25 metres over 28 years, while safe yield was revised from 20 to 24 million cubic metres a year.²⁷ A 2015 ministry account put national abstraction at 625 million cubic metres from 3,138 known licensed and unlicensed wells, more than double the 275 million safe yield. Well monitoring for 2010 showed average declines of about a metre a year across six basins, and 9 metres at the worst single well.²⁸

Morocco’s aquifers run at 100% of recharge in the Moulouya to 248% in Chtouka-Massa, with Tadla, Souss, Haouz and Saïss between 150 and 170%; national withdrawals of about 5 billion cubic metres exceed renewable groundwater by 28%.^29 30 Levels have dropped 20 to 65 metres across all basins in 30 years.²⁹

In Yemen a 2010 estimate put the annual fall in groundwater levels at about six metres in the Sanaa basin, against two and a half to four and a half in many other areas, and by 2019 western Yemen had reached its lowest level in the satellite record, which began in 2002.^31 32 Well counts disagree: about 100,000 mostly illegal wells were estimated for Sanaa and its surroundings alone, while the World Bank estimated that 100,000 tube wells might exist nationwide.^32 31

Quantity and quality fail together. As a water table drops, older and saltier groundwater moves into what was the fresh part of the aquifer.³⁴ Coastal aquifers draw seawater inland to replace what was pumped. Shallow aquifers also take in nitrate from fertiliser and sewage from unsewered districts.³⁵

Gaza is the extreme case. Some 97% of the water extracted from its coastal aquifer is unfit for human consumption against WHO standards, because the only aquifer has been depleted by over-extraction and contaminated by sewage and seawater.^36 37 A survey of 115 municipal wells found chloride averaging 1,419 mg/L and peaking at 9,491, nitrate averaging 112 mg/L against a WHO guideline of 50, and fluoride up to 2.6 mg/L.³⁵ In the 2017 monitoring round only about one well in nine met the nitrate limit and one in five the chloride limit, and salinity has risen by a third in twenty years while nitrate shows no clear trend.³⁸

On the Gulf coast the same process is measured in kilometres. At Al-Qatif in eastern Saudi Arabia the shallow aquifer runs from 4,220 to 34,090 mg/L of dissolved solids, averaging 10,108, with the intrusion front about 3.5 km inland.³⁹ In the multi-layered aquifers of the same Qatif area, dissolved solids range from 1,955 to 15,560 mg/L.⁴⁰ On the Libyan coast intrusion was already estimated to be advancing 100 to 250 metres a year in FAO’s 1997 regional survey.⁴¹

In the northeastern Nile Delta the salt has reached the soil. Electrical conductivity across surveyed fields runs from 0.53 to 49.7 dS/m and averages 22.2, with 42.8% of soil samples strongly saline and 21.4% very strongly saline, over shallow groundwater of 837 to 34,900 mg/L sitting half a metre to three metres below the surface.⁴² Modelling the seawater wedge is harder than it looks: a steady-state model can misplace its top and toe by up to 10 km compared with a palaeohydrogeological reconstruction.⁴³

Nitrate and fluoride show up in local studies rather than in a regional assessment. On the Angads plain near Oujda in Morocco, nitrate runs from 7 to 171 mg/L and nearly half of samples exceed the WHO limit.⁴⁴ Globally about a tenth of fluoride measurements exceed 1.5 mg/L, and across 15% of Africa’s land area the probability of exceeding it is above one in two; in Iran’s Bushehr province every monitored station averaged above the guideline, from 1.52 to 3.64 mg/L.^45 46

The engineering response is managed aquifer recharge: deliberately putting water underground when it is available and taking it out when it is not.⁵⁰

Abu Dhabi’s Liwa reserve, and what is actually proven

The scheme holds more than 26 million cubic metres of desalinated water in a dune aquifer, filled from the Shuweihat plant at 32,000 cubic metres a day over 27 months, with some 315 recovery wells reaching 80 metres, completed at the end of 2017, with the completion reported in January 2018, at about US$435 million.^17 50 Gulf News reported it as enough to give one million people 180 litres a day for up to 90 days.⁵¹ The launch publicity gave a fallback pumping capacity of 100 million gallons a day;¹⁷ TRANSCO’s planning statement gives a design recovery of 40 million gallons a day.⁵² Earlier figures in circulation are 17 million cubic metres injected in 2012 and a 23 million target, which is worth knowing before quoting any single volume.^34 53

A recovery efficiency of 88% is widely quoted.⁴⁷ What is documented is the pilot, where recovery through the wells around the infiltration basin worked without problems and the recovered water most likely met Abu Dhabi’s drinking water standards.⁵⁰ No published account covers a full-scale recovery cycle, so treat 88% as a claim rather than a demonstrated result.

Recharge dams, which are the region’s largest MAR programme by count

At the end of February 2026 Oman’s ministry oversaw 209 dams. Its surface-storage and groundwater-recharge dams had a combined capacity of about 458.7 million cubic metres and had impounded more than 3.17 billion cubic metres of floodwater by the end of 2025; a December 2024 ministry statement put the total at 191 dams and 357.7 million cubic metres.^54 55 56 In 2014 the stock was 89 surface retention dams, 45 purpose-built recharge dams and 14 flood protection dams, all built since 1985, and assessments in Dhofar showed recharge efficiency of up to 75%.⁵⁷

Saudi Arabia has 522 dams with 2.3 billion cubic metres of capacity, of which 1.6 billion is utilised, for runoff collection, storage and recharge.⁵⁸ The UAE’s AQUASTAT register lists 68 dams built between 1982 and 2004, including Al Tawiyeen at 18.5 million cubic metres; at the Wurayah and Tawyeen dams, 20 to 40% of stored water was measured as reaching the aquifer.^59 47

Reuse to recharge, where it exists

Bahrain has recharged the Khobar aquifer with treated effluent since 1986.⁶⁰ Oman injects treated wastewater in a managed way in exactly one place, Salalah, where the recharge has been credited with reducing seawater intrusion from 3.4 to 2.7 km.^57 47 Tunisia recharged 20 of 28 targeted aquifers with 38.4 million cubic metres in 2011, 92% of it from hill dams and only 4% from treated wastewater, under a policy that ran experimentally from the 1970s and structurally from 1992.⁶¹

Gulf aquifer storage and recovery work with published numbers includes Kabd in Kuwait, recovering 100,000 cubic metres a day from eight wells at 77% efficiency, and a pilot test at Nizwa that found the aquifer could hold 400 million imperial gallons.⁴⁷ Qatar is often listed alongside them, but the peer-reviewed work there is a siting study rather than infrastructure, identifying zones that could hold up to 182.8 million cubic metres if a scheme were built.⁶²

Abu Dhabi holds more than 26 million cubic metres of desalinated water in a dune aquifer, enough for one million people at 180 litres a day for up to 90 days.

The tracked projects in this sector and the structured procurements coming next, straight from our databases.

Projects

Most countries in the region have a system of licences or permits for groundwater use, though applying it has proven difficult in practice.⁶³ Almost none measures what comes out of them, and fewer still charge for it. The gap between the statute book and the wellhead is where groundwater policy actually fails.

• Iran: of about 416,000 authorised agricultural wells, roughly 125,000, or about 30%, carry volumetric smart meters
• Jordan: By-law 85 of 2002 licenses drilling, rigs and abstraction, but the first 150,000 cubic metres a year from a licensed agricultural well remain free of charge
• Morocco: aquifer contracts have a legal basis in Article 115 of Law 36-15, but by the state auditor's 2018 review only one had been signed against a target of ten
• Oman: 180,444 wells and 4,198 aflaj are registered, and meters have effectively never been installed beyond pilots
• Abu Dhabi: Law 6 of 2006 licenses drilling and over 80,000 wells are permitted, but farm metering was dropped after landowner resistance
• Tunisia: authorisation is required only below 50 metres, and the 9,300 deep boreholes counted in 2010 had no meters, so declared volumes cannot be checked

Iran shows the measurement gap at its largest. Of about 416,000 authorised agricultural wells, roughly 125,000 carry volumetric smart meters, about 30%. Since the Fair Water Distribution Law, at least 15 annual laws and medium-term programmes have obliged the Ministry of Energy to implement volumetric water delivery to farms.⁶⁴

Jordan has a documented enforcement record. More than 1,293 illegal wells had been backfilled or capped by 2016, 644 of them by June 2015, alongside 1,228 notices, halted rigs and stopped excavators, with meter-installation compliance reaching 95%; up to 159 drilling rigs had been confiscated by April 2015.^28 63 The pricing, though, still exempts the first 150,000 cubic metres a year from a licensed farm well: measuring without charging.²⁸

Morocco shows the other failure mode, which is an instrument that exists on paper. The aquifer contracts rest on Article 115 of the 2016 water law, piloted on Souss and Mnasra from 2007 and codified after an interministerial circular in November 2013; by the Cour des comptes’ review only the Souss contract had been signed against ten targeted by the end of 2018, the implementing decree was unpublished, Chtouka was the only gazetted safeguard zone, and more than 102,264 abstractors were operating outside the authorisation regime altogether.^65 66 Metering, a key Souss measure, was postponed.⁶³

The older statutes already provide for permits and meters. Oman declared its groundwater public wealth by royal decree in 1988 and required registration and permits from 1990, with power to set permissible discharge and require flow meters; the well inventory that followed registered more than 167,000 wells, and the law on meters was never effectively applied.^57 54 Egypt has required a ministry permit to dig any well since Article 46 of Law 12 of 1984, for no more than ten years at a time.⁶⁰ Saudi Arabia regulated drilling permits by executive order in 1989 for farms above 2.5 hectares.⁶⁰ In Algeria’s Wilaya of Blida, on the Mitidja plain, 2,000 illegal wells sit alongside 1,200 legal ones.⁶⁰ Abu Dhabi prosecuted 34 illegal-drilling cases in 2012 and 87 in 2013, and issues about 1,750 new well permits a year.³⁴

Almost every major aquifer here crosses a border, and almost none is governed by a binding sharing agreement. IGRAC’s current global map, the 2025 edition, identifies 426 transboundary aquifers, with 49 new, 41 revised and 91 removed since the previous edition.⁶⁷ For the Arab region specifically, 42 transboundary aquifer systems cover almost 58% of the land area, and every Arab state except the Comoros draws on at least one.¹ Across Africa, cooperation had been formalised for seven transboundary aquifers by 2018.⁶⁸

The regional inventory is blunt about the record. Its 26 chapters, nine on surface water and 17 on groundwater, conclude that there are no specific agreements on shared groundwater resources in Western Asia, though a few bilateral agreements include groundwater provisions.⁶⁹ That was written in 2013, which is what makes the next paragraph the exception.

Disi, 2015: the one operational aquifer agreement

Signed in Riyadh on 30 April 2015 and in force from the date of signature. It creates a protected area of about 400 km² on each side of the border, requires the elimination within five years of all activities there that depend on extracting groundwater, adds a management area of roughly 1,000 km² each side limited to municipal abstraction, and is reviewed every 25 years.^70 15 The agreement works with survey markers rather than a fixed width, so the “10 km each side” figure in press coverage should not be repeated.

Nubian Sandstone: an authority, and data sharing

Egypt and Libya created a joint authority in 1989 and adopted its constitutive agreement in 1992, seated in Tripoli; Sudan joined in 1996 and Chad in 1999.^6 71 Two further instruments on monitoring and the exchange of groundwater information followed in October 2000, and all four water ministers signed a Regional Strategic Action Plan on 18 September 2013.^71 6 None of these instruments sets national allocations.

North Western Sahara: a mechanism without a treaty

There is no treaty. A procès-verbal was endorsed separately by Algeria on 6 January 2003, Tunisia on 15 February and Libya on 23 February.⁷² Options agreed at FAO headquarters in December 2002 led through Algiers and Tunis in 2005 to the creation of a consultation mechanism and its secretariat at the Sahara and Sahel Observatory in November 2007.⁷

The Mountain Aquifer: interim arrangements, thirty years on

Governed by Article 40 of Annex III to the Oslo II agreement of 28 September 1995, under which Israel recognised Palestinian water rights in the West Bank to be negotiated in permanent status talks, a Joint Water Committee was created for the interim period, future Palestinian needs were estimated at 70 to 80 million cubic metres a year, and 28.6 million a year was to be made available.⁷³ The interim period has outlasted the arrangement.

Joint bodies for shared aquifers

Five bodies or arrangements manage or coordinate aquifers shared by the twenty countries covered here. The table lists what the sources opened for this page confirm.

Our Region Atlas maps the transboundary aquifer systems (IGRAC) alongside river basins and infrastructure.

Where the commercial and donor activity concentrates:

The bodies that commission, regulate or deliver in this sector, and the names that recur across its tenders.

• Ministry of Environment, Water & Agriculture (MEWA)Ministry · Saudi Arabia
• Ministry of Water & Irrigation (MWI)Ministry · Jordan
• Environment Agency – Abu Dhabi (EAD)Environment · United Arab Emirates
• Hydraulic Basin Agencies (ABH, ×10)Basin & resources authority · Morocco
• UN-ESCWARegional body · Regional

Mandates, procurement routes and the rest of the region’s institutions are in the decision-maker directory.

The direction of travel is not in doubt. What is genuinely uncertain is the timetable, and the uncertainty sits in storage rather than in depletion: for the North Western Sahara system, the time to 90% depletion ranges from about a decade to 150,000 years depending on which storage estimate is used.²¹ In Saudi Arabia, hydrologists cited by the USGS expect pumping of the fossil water under the irrigated desert to stay economical for only about another 50 years.⁴

The encouraging signal is that the biggest users have started acting. Saudi Arabia ended its wheat programme to save groundwater, Abu Dhabi banks desalinated water underground, and Jordan protects the Disi zone by treaty.^4 17 70 The discouraging signal is that solar pumping has removed the fuel-cost brake on abstraction, exactly where governance is weakest, and has the potential to exceed what diesel ever pumped.³²

Strategic storage has also acquired a security argument. Desalination supplies about 90% of Kuwait’s drinking water, 86% of Oman’s and 70% of Saudi Arabia’s, and in early March 2026 reported strikes damaged desalination plants in both Bahrain and Iran, and Iran’s foreign minister said water supply in 30 villages had been affected.^79 80 Groundwater management here is now less a hydrological problem than an institutional one.

Standing references for this sector.

• IGRAC, Global Groundwater Information System. The transboundary aquifer inventory, and the polygons behind the aquifer maps on this site. un-igrac.org
• Transboundary Waters Atlas, the shared-basin and shared-aquifer reference this site links to for every cross-border system. transboundarywatersatlas.org
• FAO AQUASTAT, the standing database of national water resources, withdrawals and irrigated area. The denominator behind most figures on this site. fao.org