Sigiriya archaeological site water garden hydraulics: pressure-head fountains and underground terracotta pipes?

The water gardens of Sigiriya showcase sophisticated 5th-century ancient hydraulic engineering. Water channeled from the massive Sigiriya reservoir is fed via gravity through underground interlocking terracotta pipe networks and subterranean stone masonry culverts. During monsoons, hydrostatic pressure head builds up across terraced boulder pools, operating natural pressure-head fountains on the lower fountain garden lawns without mechanical pumps. Paved subterranean cisterns store cool water that circulates through royal bath chambers.