The Geoheritage of the Water Intake of Triglio Ancient Aqueduct (Apulia Region, Southern Italy): a Lesson of Advanced Technology Insensitive to Climate Changes from an Ancient Geosite

Near Taranto (Southern Italy), the water intake of a huge ancient aqueduct, develops along the deep Triglio canyon and its branches. The water intake apparatus is a hypogeum stretch for water interception formed by tunnels converging in a single pipe, with a total length of about 4 km. The tunnels, mainly dug into limestones and calcarenites, drain the surrounding vadose zone fed by delayed infiltration of precipitation, small overlying superficial aquifers at the top of canyon flanks, or alluvial deposits covering the canyon bottom. The early hydrogeologists who designed the intake work had an extraordinary knowledge on how to drain vadose flow from unsaturated masses and how to combine the drainage from different zones, thus assuring a perennial water flow. Moreover, they were able to select the most permeable levels, only today clearly identified with advanced hydrogeological knowledge. The tunnels and the pits are in fact located between 130 and 170 m AMSL: This elevation range represents one of the specific elevation ranges recently ascertained in the carbonate platform of Murgia (Southern Italy) as marks of prolonged sea level stands. The geoarcheological study highlights the role of early hydrogeologists, forerunners of an environmental culture that led to the construction of an engineering masterstroke. It has been working for not less than a millennium, despite climate fluctuations. The sophisticated intake work of Triglio reminds the qanat or foggare, heritage of Persian, Arab, and North African culture. It is currently ascribed to the Roman period; however, it may date back to more recent times, probably to a period between the Arab (around 900 AD), and the following Norman or Swabian civilization. The dimension of the work and its outstanding technical value, which allowed its use up to date, deserve disclosure, enhancement, and conservation of this geosite as geological heritage.