From above, we see only a series of holes on the dry desert surface. But more than 30 meters below these mysterious holes is a narrow system of water channels, bringing water from a distant underground aquifer to farms and villages.

These underground water channels are called Qanat – a marvel of engineering 3,000 years ago. Many of them are still in use across Iran today.

Starting in the Iron Age, ancient people surveyed for water sources at high alтιтudes, often at the beginning of a river valley or a cave lake. Once they found one, they would create inclined tunnels to carry the water to where it was needed.

The holes visible above ground are air ducts, used to bring out the sand and provide oxygen to the workers digging the Qanat by hand below. Eventually, the tunnel system was led out into the open, forming lush oases.

Underground structures in the desert are as long as the distance from Earth to the Moon pH๏τo 1

The construction of the Qanat was painstaking work, even requiring great precision. The angle of the conduit had to be steep enough to allow water to flow without pooling, but if it was too steep, the fast-flowing water would corrode and collapse the tunnel.

Despite the difficult work, and the tunnels requiring annual maintenance after completion, the irrigation tunnel system allowed agriculture to flourish in the barren desert.

The technology of digging Qanat tunnels spread through Silk Road trade and Muslim conquests. Today, Qanat can be found as far away as Morocco and Spain.