What did Karez / Qanat Underground Canal look like?

Composed of vertical shafts (for construction and ventilation), underground channels (water conveyance), open channels (irrigation), and reservoirs (water storage).

How did Karez / Qanat Underground Canal work?

Groundwater from piedmont alluvial fans → underground channels flow by gravity along gentle terrain slope → water flows underground with zero evaporation → reaches oasis outlet → open channels distribute water for irrigation → reservoirs store backup water.

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Karez / Qanat Underground Canal

An underground canal water conveyance system using terrain gradient for gravity flow, minimizing surface evaporation — the most efficient hydraulic engineering for arid regions.

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Scientific Principle

Groundwater dynamics: underground channels intercept the phreatic zone flow using gravity. Hydrology: underground channel conveyance has zero evaporation loss.