An hydraulic engineering analysis of the public Lacus fountains in Roman Pompeii

The ancient Roman water supply has been the object of a variety of studies in the last ten years, due to the new excavation campaigns promoted in various countries and the application of new methods and sciences to traditional archaeology. This thesis document presents advances in the knowledge of the technologies used for the water distribution in Pompeii in Roman times, focusing on the supply of the public street fountains. Two methods for estimating the water supplied to each fountain are presented: a first one makes use of the new data gathered on the fountain basins, to calculate a range for the discharge of the overflow channels; the second one considers the possible supply pipelines, and from the elevation data and the possible pipelines length, estimates a range for their discharge. The two methods are finally compared to present some considerations on the total water demand of public fountains and on the water brought in town by the known aqueduct channel. In support of the calculations, new experimental data on the absolute roughness of the ancient pipes, is presented; based on the range of values estimated for the absolute roughness, values of the friction factor are obtained for all the standard ancient Roman lead pipes from the Colebrook-White equation and presented in tables. The thesis results indicate that the Pompeian fountains, characterised by an average basin volume of 0.7 m3 and an average diameter of the supply pipe of 3.3 cm, were probably supplied with a flowrate in the range 0.08 - 1.18 l/s, according to the average overflow channels’ discharge, and in the range between 0.2 - 2.5 l/s according to the pipelines discharge. The results on the fountains supply support the analysis of water balances at water towers and the hydraulic calculation of the main pressure network; to estimate the flowrates supplied to private buildings, a methodology and an example is presented in the final chapter, suggesting a topic for future post-doc research