In southern Italy, the pristinely preserved remains of the ancient Roman city of Pompeii have mystified historians and archaeologists since they were rediscovered nearly 300 years ago. Ongoing expeditions continue to reveal new details about the city and its people, believed to have been decimated by the sudden eruption of nearby Mount Vesuvius around 79 CE.
Archaeological Park of Pompeii (APP) researchers have spent two years uncovering new details about how ancient Pompeian engineers approached stormwater management. They surveyed 457 m (1500 ft) of stormwater tunnels that once carried runoff from the city’s center toward the Bay of Naples. APP is now working to restore functionality to the ancient tunnels while respecting and preserving their historical value, said park director Massimo Osanna. Bound by the Volturno River and the Apennine Mountains, heavy rainstorms presented – and continue to present — severe flooding risks to low-lying Pompeii.
“Since we have problems today with flooding from rain, we will start using [the tunnels] again,” Osanna told The (London) Times in February. “The fact we can do this is testament to the excellent engineering skills at the time.”
Archaeological researchers had known about the existence of an expansive tunnel system underneath Pompeii for decades, describes an APP release about the discovery. However, previous expeditions underground had different goals, and uncovered only the most basic information about how the tunnels functioned, when they were built, or how far they stretched.
Because of the logistical difficulty of navigating these underground structures without disturbing their archaeological provenance, APP enlisted professional cave analysts from the Cocceius Association to comprehensively map and study the narrow tunnel system.
At the former site of the Civil Forum, a main gathering place and one of the most heavily trafficked areas in the city, a system of surface-level storm drains directed rainwater into two large, stone cisterns underground. Runoff collected in the cisterns would feed into rudimentary tunnels, also carved through stone, that ran beneath the busy Via Marina thoroughfare and into the Bay of Naples.
Evidence of the survey suggests the tunnel system evolved over three distinct historical periods, which could mean the channels served Pompeii residents for approximately 300 years. Researchers believe the oldest parts of the system date back to the late 3rd-century BC, around the death of Alexander the Great and before the rise of the Roman Empire. Extensions to the tunnels are thought to have been made during the 1st-century BC, around the reign of Augustus Caesar, first emperor of Rome. APP describes that some parts of the system appear slightly newer, likely within the decades leading up to the city’s eventual destruction.
After the entire system is cleared of debris and the drains — until recently blocked by soil, ash, and other obstacles — are reopened, the tunnels will soon convey stormwater runoff for the first time in nearly 2,000 years, according to APP.
“This initial, but complete, exploration of the complex system of underground canals confirms the cognitive potential which the Pompeian subsoil preserves and demonstrates how much still remains to be investigated and studied,” Osanna said.