The Canale di Comunicazione Traverso in Portus: the Roman sea harbour under river influence (Tiber delta, Italy)

Portus was Rome’s maritime port during the Roman Empire. In AD 42, the harbour location was selected about 3 km north of Ostia, along the Tyrrhenian coast, on the margin of the Tiber River. Portus and its maritime façade are well known, however the fluvial aspects of Portus are poorly documented. How did Roman engineers preserve a continuous waterway from the basins of Portus to the Tiber River without accelerating siltation inside the harbour? Were their choices efficient? The present Canale di Comunicazione Traverso is the only canal attested to link the Tiber River and the harbour basins. The objective of this work is to analyse the Canale Traverso sediments infill in order to establish the role of this canal in relation to the infill deposits of the harbour basins and to define the functions of the canal. This study is based primarily on a reinterpretation of the available archaeological data, as well as mainly on sedimentological analysis and the interpretation of the Passega diagram. A Passega diagram is presented for understanding the deposit processes for the harbour environments at the entrance to the Trajanic basin (TR-XIV). This diagram is compared to the Passega diagram of the Canale Traverso (CT-1) which is characterised by a stronger influence of the Tiber River. This study concludes that the Canale Traverso was a canal that was well protected from the influence of the Tiber River, with the exception of occasional flooding. Also, this paper presents the patterns of sedimentation at Portus and allows us to define the use of the canal and the maintenance procedure

Dredging and canal gate technologies in Portus, the ancient harbour of Rome, reconstructed from event stratigraphy and multi-proxy sediment analysis

Ancient harbours are rich archives of human-environment interaction. However, dating harbour deposits and correlating their stratigraphy is a major challenge because of typically high sedimentation rates over short periods and possible curative dredging events. Portus, the maritime harbour of Rome at the height of the Roman Empire, was a port complex composed of basins and canals connecting the commercial harbour to Rome via the Tiber River. Sediment core CPS1 in the narrowest of these canals, Canale Traverso, is located centrally in what was the capital city's commercial hub and contains a continuous harbour depositional record with average sedimentation rates greater than 1 cm per year. Here we use piston coring, high-resolution core scanning and a multi-proxy sediment analysis including for the first time paleo- and rock-magnetism, and bulk and clay mineralogy in order to overcome the problems of dating harbour deposits and correlating their stratigraphy. The method allowed precise identification of major reworked events, including a dredged deposit and a hyperpycnal deposit, which improve the chronostratigraphy and water depth reconstruction, and sheds light on harbour technologies at the height of the Roman Empire. A debris layer with abundant ceramic fragments and rocks marks the decommissioning of Canale Traverso and provides a new chronostratigraphic marker at Portus. Multi-proxy riverine input signatures point to the possible use of canal gate technology for water flow management

Géoarchéologie du delta du Tibre: evolution géomorphologique holocène et contraintes hydrosédimentaires dans le système Ostie-Portus

Ostia and Portus are two important harbour cities located on theThyrrenian coast, near the ancient Rome. This location corresponds to a fastly changing landscape (river and coastline mobility). The aim of this study is to reconstruct the Tiber hydrosedimentary dynamics in its delta plain during Ancient times (mainly in the 1st c. BC - 1st c. AD) and to identify their impact on the system Ostia-Portus. To complete this work, we analyse sedimentary cores drilled in the palaeomeander of Ostia and the canals of Portus. These results are compared to the archaeological and historical data.Crossing sedimentary, archaeological and textual data allows to consider hydrosedimentary anthropoclimatic crisis in the Tiber River watershed, during the period between the second part of the Ist century BC and the beginning of the Ist century AD. This crisis is expressed in Ostia, by: (1) a sediment accumulation at the mouth of the Tiber River, leading to the filling of the river mouth harbour of Ostia; (2) several major floods (at Rome - sometimes torrential floods); and (3) perhaps an increase of the groundwater levels. During this hydrosedimentological crisis or before, a strong lateral mobility of the Tiber mouth and the palaeomeander of Ostia probably affect the development of the city.Obliged by a strong demographic pressure in Rome and by the socio-economical context, Claude built Portus in the middle of the 1st century AD. Portus is planned with the idea to overcome the shortcomings of Ostia’s harbour: (1) by an increased harbour basin area (200 ha), and (2) by its establishment, 3 km north of the Tiber mouth, to avoid the main hydrosedimentary constraints. For logistical reasons (goods transport to Rome), Portus includes a fluvial canal system, connected to the Tiber River. However, Roman engineers take care to separate the canal system and the harbour basins (sediment load) and some of these canals are considered floodways (flood management). Sedimentary analysis characterise the canal functioning and filling (Canale Traverso, Canale Romano).This work is complemented by a methodological reflection on the Passega diagram and by a modeling of the Holocene evolution of the Tiber delta’s northern part, based on the analysis of core samples

Canal through time: a technological answer to socio-environmental variability? Roman Canal studies

Canal through time: a technological answer to socio-environmental variability? Roman Canal studie

The Development and Characteristics of Ancient Harbours—Applying the PADM Chart to the Case Studies of Ostia and Portus

International audienceOver the last 20 years, the geoarchaeology of ancient harbours has been a very active area of research around the Mediterranean basin, generating much palaeoenvironmental data from many sites, including estimations of sedimentation rates, the height of the ancient sea-level at different dates and palaeo-geographical reconstructions. Combining this information has proved a major challenge. This article proposes a new chart called the Palaeoenvironmental Age-Depth Model (PADM chart), that allows the researchers to combine all relevant indicators in order to estimate harbour potential of a given ancient port, and to generate comparable data between harbours in terms of degree of closure and water depth available against a synchronised chronology. This new approach, developed in the context of the ERC-funded RoMP Portuslimen project, takes into account estimations of water depths relating to differing Roman ship draughts at different periods. It is tested against the palaeoenvironmental evidence published over 10 years from two Roman harbours located at the mouth of the river Tiber: Ostia and Portus. This reveals that: (1) there has been an underestimate of the real sedimentation rates due to the margins of error of the radiocarbon dates; (2) there was effective control of the water column by dredging; (3) there were different periods of control of the sedimentation. We suggest that the navigability of the Ostia harbour by ships with shallower draughts was maintained until sometime between the 2nd c. BC and 1st c. AD, while at Portus it was retained until the 6th—7th c. AD

Introduction to the special issue: Roman canals studies—main research aims

Introduction to the special issue: Roman canals studies—main research aimsIntroduction to the special issue: Roman canals studies—main research aim

Long-term interactions between the Roman city of Ostia and its paleomeander, Tiber Delta, Italy

This study examines the long term interactions between the well-known Roman city of Ostia and a river meander. Located at the mouth of the Tiber River, Ostia was a major harbor city that connected Rome to the Mediterranean Sea. Based on aerial photography and boreholes analysis, the paleodynamics of the Fiume Morto’s paleomeander are understood to be linked to the urban evolution of the city of Ostia. Four periods of evolution have been identified as a result of this interdisciplinary work: (1) the foundation of Ostia’s urban center, in the 4th – 3rd century BC, occurred when the meander already existed; (2) between the 4th century BC and the 3rd century AD, human/environmental interactions contributed to the compound growing of the meander which possibly eroded an important Roman road linking Ostia to Rome; (3) from the Imperial period until the meander was cut off in AD 1557-1562, the constricted meander channel at the apex led to the stability of the downstream river channel; (4) the cut off of the paleomeander was completed in 1562, leading to the filling of the paleochannel. These successive phases of channel evolution mark changing fluvial risks from the Roman period to today

Observations on Palaeogeographical Evolution of Akrotiri Salt Lake, Lemesos, Cyprus

Akrotiri Salt Lake is located 5 km west of the city of Lemesos in the southernmost part of the island of Cyprus. The evolution of the Akrotiri Salt Lake is of great scientific interest, occurring during the Holocene when eustatic and isostatic movements combined with local active tectonics and climate change developed a unique geomorphological environment. The Salt Lake today is a closed lagoon, which is depicted in Venetian maps as being connected to the sea, provides evidence of the geological setting and landscape evolution of the area. In this study, for the first time, we investigated the development of the Akrotiri Salt Lake through a series of three cores which penetrated the Holocene sediment sequence. Sedimentological and micropaleontological analyses, as well as geochronological studies were performed on the deposited sediments, identifying the complexity of the evolution of the Salt Lake and the progressive change of the area from a maritime space to an open bay and finally to a closed salt lake