MENA Water Review · Visual story
Underground Rivers
Nearly three thousand years ago, engineers here worked out how to move water across a desert without a pump. Tens of thousands of those tunnels are still running, and a single nearby borehole can dry one out.
It cannot over-pump, because it can only take what gravity delivers.
Imagine having no electricity, no diesel and no steel pipe. Your village is on a dry plain. The water lies fifteen kilometres away and a hundred metres underground, beneath the gravel fan at the foot of the mountains. You need that water to arrive every day, for ever.
The solution Iranian engineers developed from about 800 BCE spread from Morocco to western China. First, you sink a well into the water-bearing gravel high in the fan. This is the mother well. Then you dig a tunnel from the village towards the mother well, giving it a very slight, steady fall. The fall must be enough for water to flow, but not so steep that the flow tears the tunnel apart. The system needs no power. With maintenance, it can run for centuries, and it cannot take more water than the aquifer provides.
A mother well reaches the water table under the gravel fan. A tunnel runs from it back to the village, falling just enough for gravity to move the water. The shafts along the route are for spoil, air and repair.
The tunnel takes only the water the aquifer delivers to it. There is no mechanism by which it can take more, and it uses no energy at all.
A modern well is drilled nearby, into the same aquifer, with a pump that can lift water from far below the tunnel.
The pump draws the water table down past the tunnel floor. The qanat has no way to follow it, so it simply stops. The flow cannot return until the table does.
Schematic rather than measured. In Iran these are qanats; in Oman and the UAE, aflaj; in Morocco, khettaras; in Algeria, foggaras. The cross-section barely changes.
The gradient had to be surveyed in the dark, without instruments.
The difficulty is maintaining that fall. If the tunnel is too steep, running water erodes it and causes it to collapse. If it is too shallow, the water stagnates. The gradient therefore had to remain gentle and steady along a tunnel that might run for many kilometres underground. Workers surveyed and excavated the route without modern instruments, digging from the bottoms of vertical shafts sunk at intervals along it. From the air, those shafts appear as a row of craters. They are the most recognisable sign of a qanat anywhere in the world.
The remarkable fact is how long these systems have survived. In some places, the tunnels have been maintained for millennia; elsewhere, they have lasted for centuries through conquests, plagues, empires and the arrival of the nation state. No pump, turbine or pipeline built in the industrial era has an operating record anything like it.
The law that shares the water is the other half of the invention.
In Oman, a falaj’s water is divided into time-shares. During each share, historically measured by sundial during the day and by the stars at night, the holder can direct the flow onto their land. These shares are property: they are inherited, bought from their owners and rented at regular auctions. Water owned by the falaj itself is also rented out, and the proceeds pay for maintaining the channel.
Read that list again with a modern water regulator in mind. It describes defined, tradeable entitlements; allocation by time; market pricing for rented water; revenue reserved for maintaining the asset; and management by the users themselves. This is close to what modern water reform sets out to build, yet the system has been operating for centuries.
What is left, and what has stopped
Different measures on one panel: the first two bars are systems still running as a share of those recorded, the third is the share of listed khettaras in the Tafilalt that have gone dry. Read them as three separate facts rather than a series.
What kills a qanat is not age or neglect. It is a pump.
A qanat is fed when its tunnel intersects the water table, allowing groundwater to enter it. If a modern well nearby draws the water table below the tunnel floor, the qanat stops flowing. It cannot compete because it has no way to reach deeper water. Khettaras and motor pumps cannot coexist: wherever they compete, the pumps prevail.
That has been the story of recent decades across the region. Motor pumps and drilling rigs, followed more recently by cheap solar pumping, have put a deeper straw into the same glass. In Iran, a 2017 official count put the qanats still in use at 37,000 out of 120,000. In Morocco’s Tafilalt, 321 of 386 listed khettaras have dried.
- c. 800 BCE
The technology appears
Qanat construction develops in Iran and begins to spread with the Persian empire.
- 7th c. CE on
West with the Arab conquests
The method travels across North Africa and into Spain, and east as far as Turpan in western China. The names change; the cross-section does not.
- 20th c.
The pump arrives
Motor pumps and drilling rigs reach the same aquifers, able to lift water from far below any gravity tunnel.
- 2017
The Iranian count
An official count puts the qanats still in use at 37,000, out of 120,000 recorded.
- 2016–
On the World Heritage list
Eleven Iranian qanats and five Omani aflaj are inscribed by UNESCO.
- 2026
Oman keeps paying for upkeep
Oman signs 49 contracts worth RO 1.19 million to restore 64 aflaj in North Batinah.
The question is not whether to build new ones. It is whether to regulate the boreholes.
It would be sentimental to argue that the region should return to qanats. Nobody is going to supply Riyadh or Cairo through a gravity tunnel, and the systems that survive serve villages and oases rather than cities. The case for taking them seriously is narrower, and stronger, than nostalgia.
First, they are still delivering water. Thousands of Omani aflaj and Iranian qanats still carry water to farmland at no energy cost, and governments still consider them worth maintaining. In 2026, Oman signed 49 contracts worth RO 1.19 million to restore 64 aflaj in North Batinah.
Second, and more usefully, they embody a principle that the region is now rediscovering at great expense: groundwater abstraction should be physically limited to what the aquifer can provide, while access is governed by entitlements that people recognise as property and will police themselves. Whether a technology that has operated for millennia survives this century depends on the boreholes around it, not on the tunnels themselves.
Images: Falaj Al Khatmeen, Birkat Al-Mawz © Dr. Thomas Liptak (CC BY-SA 4.0); inside a qanat © ninara (CC BY-SA 2.0); khettara line in the Tafilalt © Sebastian Lapostol (CC BY-SA 4.0). Via Wikimedia Commons.
Sources
13 references
Counts of working systems are official or survey figures and are not directly comparable between countries. The cross-section is schematic and not to scale.
- FAO, Globally Important Agricultural Heritage Systems, Qanat Irrigated Agricultural Heritage Systems, Kashan, Iran.
- Taghavi-Jeloudar, M., Han, M., Davoudi, M. and Kim, M. (2013), “Review of ancient wisdom of qanat, and suggestions for future water management”, Environmental Engineering Research 18(2): 57–63, doi:10.4491/eer.2013.18.2.057.
- UNESCO World Heritage Centre, The Persian Qanat (archived).
- Beraaouz, M., Abioui, M., Hssaisoune, M. and Martínez-Frías, J. (2022), “Khettaras in the Tafilalet oasis (Morocco): contribution to the promotion of tourism and sustainable development”, Built Heritage 6: 24, doi:10.1186/s43238-022-00073-x.
- Idda, S., Bonté, B., Kuper, M. and Mansour, H. (2021), “Revealing the foggara as a living irrigation system through an institutional analysis: evidence from oases in the Algerian Sahara”, International Journal of the Commons 15(1): 431–448, doi:10.5334/ijc.1128.
- Tehran Times, “37,000 qanats still in use across Iran”, 4 November 2017.
- UNESCO World Heritage Centre, Aflaj Irrigation Systems of Oman (archived).
- Brown, R. (2017), “See the ancient water tunnels below Iran’s desert”, National Geographic, 31 May 2017.
- Med-O-Med, “Aflaj irrigation system, Oman”, cultural landscape file.
- Powers, D. and Al Ghafri, A., “On the equity of revenue creation in a community based water management system”, Aflaj Research Unit Working Paper 0213, University of Nizwa.
- FAO AQUASTAT, country profile: Oman (2008 edition, archived).
- Conflict and Environment Observatory, “Groundwater depletion clouds Yemen’s solar revolution”, April 2021.
- Muscat Daily via Zawya, “49 agreements worth $3mln signed to restore 64 aflaj in Oman’s North Batinah”, 2026.
Every figure and claim in this story rests on the references above. The stories list them here rather than marking them in the text; the country reports and hubs keep their inline markers.