The qanat
Gently sloping tunnels bring mountain groundwater tens of kilometres across desert without evaporating.
- When
- —
- Duration
- 300 years
- Known to
- ± 200 years
- Era
- Iron Age, Holocene
Developed in Iran from around 800 BCE, a qanat is a nearly horizontal tunnel driven into an alluvial fan until it meets the water table, then run downhill to the surface, with vertical shafts for spoil and ventilation. Because the water never sees the sun, almost none is lost. Some run for over 70 kilometres. The technique spreads from Morocco to China and makes settlement possible in places with no surface water at all.