Underground work in the desert is as long as the Earth's distance to the Moon

The total length of thousands of underground waterways in the Iranian desert is equivalent to the distance of the Earth to the Moon (384,400km).

Looking from above, we only see a string of holes on the arid desert surface. But more than 30 meters below these mysterious holes are a narrow waterway system , bringing water from distant aquifers to farms and villages.

These underground waterways are called Qanat - the great works of the engineers 3000 years ago. Many of them are still used throughout Iran today.

Looking from above, we only see a string of holes on the arid desert surface.

Beginning in the Iron Age, ancient inhabitants surveyed water sources at high places, often the origin of river valleys or a cave in the cave. Once found, they will create inclined tunnels to bring water to where needed.

The visible holes on the ground are ventilation pipes, used to bring sandy soil out and provide oxygen to the Qanat digging workers by hand below. Finally, the tunnel system was exposed, forming green oases.

These underground waterways are called Qanat.

The construction of Qanat is a hard work, even requiring high accuracy. The angle of the path must be sufficiently inclined so that the water can flow without condensation, but if it is too steep, fast flowing water will corrode and collapse the tunnel.

Even though it is a difficult job, after completing the tunnels, it needs annual maintenance, but the irrigation tunnel system allows agricultural development in the barren desert.

The construction of Qanat is a hard work, even requiring high accuracy.

Qanat tunneling technology spread through commercial activity on the Silk Road and conquests of Muslims. Today, Qanat can be found in remote places like Morocco and Spain.

For Komeil Soheili, an Iranian filmmaker, Qanat is an integral part of the landscape of Khorasan province, his hometown.

Soheili said: 'The diversity of landscape and culture in Iran is something that the world does not understand. One of the oldest civilizations in the world comes from the great work - the Qanat tunnel '.

Today, Qanat can be found in remote places like Morocco and Spain.

Gholamreza Nabipour, 102, is one of the last and almost certainly the oldest man in the Mirab profession - taking care of the Qanat.

In 2016, UNESCO recognized the Persian Qanat as a world heritage.