The lack of surface water and a high potential for evapotranspiration are the climatic and hydrological characteristics of the arid and semi-arid Middle East regions. In foothills regions the groundwater, often supplied by partially buried alluvial fan systems, has been intercepted and conveyed through the creation of a highly efficient supply system known as 'qanat', 'karez' or 'foggara'. This ancient hydraulic technology spread on a large scale since the 6th century BCE, during the rise and development of the Persian Empire. It consists in the excavation of a series of vertical tunnels, like large wells, which are connected by a gently sloping underground channel bringing water by gravity. Through the centuries, the qanats have been not only a sustainable system for exploitation of groundwater resources but also an important factor for the socio-economic and cultural development of local communities. In this paper the Authors illustrate the main aspects of qanats under historical, cultural and socio-economic perspective and the recent decline of the qanat system. An original and still updating database of these type of hydraulic operas, implemented through the collection and analysis of documentary sources, cartographic data, and on-site measurements is then presented. The database, including qanats detected on regional to local scales, might be regarded as a valuable support for the recovery of these structures and a more efficient governance of water resources. [ABSTRACT FROM AUTHOR]