The aqueducts supplying water to the Eternal City are one of the most famous achievements of the builders of ancient Rome. Scientists from the University of Illinois at Urbana-Champaign have just solved the mystery of one of them. Based on studies of limestone sediments, they determined how much water was supplied to Rome by the Anio Novus aqueduct. They write about it in the latest issue of the Journal of Archaeological Science. The Anio Novus aqueduct has provided water to Rome for hundreds of years. It was 87 kilometres long and was drawing water from the Aniene River in the Apennines. Its construction began in the reign of Emperor Caligula in 38 CE and was completed under Claudius in 52 CE.
Illinois researchers analyzed the system of travertine sedimentary layers that had formed in the flowing water and calculated that the aqueduct was flowing about 1.4 cubic meters of water per second. At this rate, the aqueduct provided enough water for the city for 3 seconds per second. an hour shower or 7 average baths, says the study’s first author, professor of geology and microbiology, Bruce Fouke.
The travertine sediments, investigated in the area of Roma Vecchia, where Anio Novus is the best preserved, indicating that the aqueduct was practically always full of water, but that accumulating sediment limited its flow. Therefore, the latest result shows less flow than previously thought. Settlements limited it by up to 25 per cent.
Researchers have also revealed probable ancient frauds. Previous estimates were based on an account in 97 from Rome’s Commissioner for Water Supply, Sextus Julius Frontinus, in the text “De Aquis”. We have the impression that this data is not reliable, as there were no exact methods of measurement at the time flow of water – emphasizes Fouke. There are many inaccuracies in Frontinus’s data, which he explains not only with measurement errors, but also cases of water theft, and finally cases of fraud in the water management office itself – he adds.
Earlier flow measurements were also based on not entirely correct estimates of water velocity. Meanwhile, the differences in the slope of the aqueduct, shown in the latest research, indicate that in some places the speed of the water changed by more than a meter per second. This dramatically changes the estimate of the volume of water transported.
No matter what the concrete results of the calculations may be, it cannot be denied that the aqueduct system was crucial to the development of the Eternal City, emphasizes Fouke. It was this stable water supply that allowed Rome to increase its population in the first century CE, up to 600,000 or even a million – he points out.