How did ancient canals and aqueducts reduce water loss from evaporation?

Ancient engineers utilized specific construction techniques to mitigate water loss from evaporation in their irrigation systems. A primary method involved building significant portions of their aqueduct networks underground. By conveying water through subterranean conduits rather than open channels, they effectively shielded the supply from direct exposure to the sun and wind, which are the primary drivers of evaporation.1

While the primary focus of ancient canal and aqueduct engineering was often the transport of water over varied terrain—using gravity to maintain necessary gradients—these underground stretches served as a critical conservation measure in arid regions. In addition to these structural designs, ancient systems relied on complex engineering, such as dikes, embankments, and dams with sluice gates, to manage water flow and distribution, ensuring that water was moved and stored as efficiently as possible to support agricultural needs.213