The Sahara Desert once had 750 km of water tunnels

The Garamantes empire once flourished by using technology to exploit groundwater in the Sahara desert but fell into ruin when the groundwater dried up.

The area where the ancient Garamantes lived. Photo: NASA/Luca Pietranera

With low rainfall and high temperatures, the Sahara Desert is one of the harshest and most inhospitable environments on Earth. Although the Sahara was periodically much greener in the past, an ancient society lived in a similar climate today by finding a way to collect water in the arid desert until the water supply ran out, according to Phys . org .

New research about to be published at the GSA Connects 2023 conference on October 16 of the Geological Society of America describes a series of favorable factors that allowed the ancient civilization in the Sahara, the Garamantes empire, to exploit underground water below. ground, sustaining society for nearly a millennium before running out of water.

According to Frank Schwartz, a professor in the School of Earth Sciences at Ohio University and lead researcher, monsoon rains transformed the Sahara into a relatively lush environment 5,000 to 11,000 years ago, providing surface water resources and habitable environments for developed civilizations. When the monsoon rains stopped falling 5,000 years ago, the Sahara turned into a desert and many civilizations withdrew from the area.

The Garamantes lived in the southwestern Libyan desert from 400 BC to 400 AD under hyper-arid conditions similar to today's and were the first urbanized society to form in a desert lacking a continuous flowing river. The lakes and rivers of the lush Sahara had long since disappeared by the time the Garamantes moved in, but large amounts of water remained stored in the sandstone layer, potentially one of the largest aquifers in the world. gender, according to Schwartz.

Camel trade routes from Persia through the Sahara provided the Garamantes with the technology to collect underground water, using underground aqueducts or aqueducts. This method involves digging a gently sloping tunnel on a hillside to just below the water table. Groundwater will then flow into the tunnel, to the irrigation system. The Garamantes dug a total of 750 km of underground tunnels and steep tunnels to collect groundwater, with construction activity at its heaviest from 100 BC to 100 AD.

Schwartz combined archaeological research with hydrological analysis to understand how topography, geology, and rainfall through the land created ideal conditions for the Garamantes to exploit groundwater. According to him and his colleagues, the Garamantes had great environmental luck with previous wet weather, suitable terrain and unique groundwater conditions for the tunnel technology to work. However, their luck ended when the water table dropped below the surface of the tunnel, causing the empire to perish.