Ancient aqueduct carbonate deposits as a high-resolution archive for the environment and archaeology

Project Information

AQUEA

Grant agreement ID: 890454

DOI

10.3030/890454

Project closed

EC signature date 28 March 2020

Start date 11 October 2021

End date 10 October 2023

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 212 933,76

EU contribution

€ 212 933,76

Coordinated by

THE CHANCELLOR, MASTERS AND SCHOLARS OF THE UNIVERSITY OF OXFORD
United Kingdom

Periodic Reporting for period 1 - AQUEA (Ancient aqueduct carbonate deposits as a high-resolution archive for the environment and archaeology)

Reporting period: 2021-10-11 to 2023-10-10

Summary of the context and overall objectives of the project

The Roman Empire was the first modern world, a multicultural amalgamation of nations, with highly developed economy and technology. One of the outstanding achievements of Roman culture was the development of aqueducts, elaborate systems to deliver fresh water to urban centres. The aqueducts are important for two reasons; they are the cultural and technological expression of a society that is our direct ancestor, with similarities and differences, and a study of aqueducts reveals much about this ancient society. Also, aqueducts transported water, one of our most precious resources, and can provide a benchmark on availability of water in the past. Modern water supply systems still use the same sources that the Roman engineers used, and an understanding of the state of groundwater and springs in antiquity is important to determine the future of the water reserves and supplies on which we will have to rely on in future.
Ruins of ancient aqueducts can reveal much about their construction and functioning, but not about the way they were operated, and about the kind and amount of water flowing through them. However, many aqueducts deposited calcium carbonate sediments which can provide such information.
Calcium carbonate deposited in Roman aqueducts is a new, high-resolution archive for environmental and archaeological studies. Aqueduct carbonate stores information on short- and long-term variations in temperature, rainfall, vegetation cover and traces of earthquakes, droughts, floods, wildfires, and volcanic eruptions with up to daily resolution. Yet, aqueduct carbonate offers comprehensive anthropogenic information through its connection to settlements served by water supply systems in which the archive formed. This applies because the archive is forming at the heart of ancient cities and recording the environment and society. This originality of aqueduct carbonate provides the opportunity to study the historical past, human interference with the environment, human activity aspects such as ancient water management and the impact of environmental forcing, natural or self-inflicted, on society, in the middle of urbanism. Hence, during this action, we investigated the potential of the carbonate archive in three aqueduct carbonate series from neighbouring sites in Southern France.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

We learned that structural variation and age of aqueduct carbonate, even for neighboring sites, can be highly variable, making correlation challenging. To investigate the effect of climate, we added a fourth aqueduct further to the west, in Cahors in central France. Each aqueduct showed different results. Annual environmental signals were observed in the aqueduct carbonate of Arles but the deposits apparently cleaned of earlier deposits and date from late antiquity. The aqueduct of Bellegarde showed no annual layering, but mainly information on the source. The aqueduct of Nîmes, which includes the famous Pont du Gard, showed both annual and pluri-annual environmental signals with little anthropogenic influence, and this series can serve to obtain detailed local information on the climate in Roman Provence. In the Cahors aqueduct carbonate, we could study the human activity in the form of regular cleaning episodes.
Aqueduct carbonate was investigated using stable isotope, trace elements, spectrofluorescence and optical microscopic observations. This was done on number of sections of the aqueduct carbonate from different sites along each aqueduct, starting from spring and ending with the last sample at the end of the aqueduct, in the city. The reason for multi-km sampling was to see changes along the length of the aqueduct, mainly anthropogenic changes made due to cleaning or water withdrawal. For example, we discovered that for the aqueduct of Nîmes, thickness of the carbonate series was very variable, and that stratigraphy along the aqueduct varied in content. We could determine that this was because the aqueduct water was diverted for a water lifting machine for agricultural activities, while other stratigraphic variations were probably due to cleaning, leaving carbonate of different age in different parts of the structure. Such variations make interpretation more difficult, but also expand the total length of the archive available for study. The paper relevant to these conclusions is in progress and will be published in 2024.
In the course of this project, we published in Cahors where we interpreted periodic cleaning breaks and techniques and could address questions on the frequency of cleaning changed and how the aqueduct was abandoned. In the review paper, we summarized the state of the art on research of aqueduct carbonate, based on our experience and on previous papers on the subject, to give an overview to the reader and to a new generation students on the subject of ancient water management. Detailed interpretations were given by numerous authors in order to testify use of aqueduct carbonate in different aimed studies. The importance of the review is to bring public awareness to these new archives. The overall objective is to promote studies on aqueduct carbonates, in order to understand the history of water management.
I have organised a workshop where I presented the results for the first time during which I invited number of people doing the same aqueduct carbonate study. Beside the two-day workshop, I also disseminated this work with a press release. This gave the opportunity to meet with interested listeners in BBC and Jack FM in Oxford.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

At the start of this project, aqueduct carbonate was regarded as a simple environmental archive like speleothems, but with a higher resolution because of thicker annual layers, and a direct link to ancient archaeological sites. This would valuable but not unique, since speleothem data can be obtained from a very large number of natural sites. Our study has now revealed the true value of ancient aqueduct carbonate deposits: they can provide invaluable archeological information on the working and maintenance of ancient water supply systems, and on the health and status of ancient socio-economy; water systems are maintained when society is healthy and well-functioning, but neglected in times of stress, and such signals are visible in all investigated aqueducts of this study. The archaeological information is important to understand the level of technology and engineering in antiquity, and the way this worked. This is not only interesting from a historical point of view: ancient technology worked with simple techniques without use of complex modern tools and energy sources. Simple solutions may lie hidden in these ancient water systems which can be applied today for our present energy transition. Finally, the environmental signals stored in ancient aqueduct carbonate is an addition to knowledge derived from other environmental archives since it provides local observations linked directly of ancient cities, and thus shows the effects of environmental extreme events on ancient societies. For example, we derived a 220-year environmental record for the aqueduct of Nîmes. Also, the ancient water supply systems tapped the same aquifers we used today and can provide a benchmark on their status in the past, and the way they reacted to weather and extreme environmental effects over centuries. The societal implications is in line with the proposed work, as two days workshop took the attention of people outside of the academy.

the flyer of the workshop