Sustainability of underground hydro-technologies: from ancient to modern times and toward the future

An underground aqueduct is usually a canal built in the subsurface to transfer water froma starting point to a distant location. Systems of underground aqueducts have been applied byancient civilizations to manage different aspects of water supply. This research reviews undergroundaqueducts from the prehistoric period to modern times to assess the potential of achieving sustainabledevelopment of water distribution in the sectors of agriculture and urban management, and providesvaluable insights into various types of ancient underground systems and tunnels. The review illustrateshow these old structures are a testament of ancient people's ability to manage water resources usingsustainable tools such as aqueducts, where the functionality works by using, besides gravity, only"natural" engineering tools like inverted siphons. The study sheds new light on human's capabilityto collect and use water in the past. In addition, it critically analyzes numerous examples ofancient/historic/pre-industrial underground water supply systems that appear to have remainedsustainable up until recent times. The sustainability of several underground structures is examined,correlated to their sound construction and regular maintenance. Moreover, several lessons canbe learned from the analysis of ancient hydraulic works, particularly now, as many periodicallyhydrologic crises have occurred recently, overwhelmingly impacted by climate change and/orover-exploitation and degradation of available water resources.