Les aqueducs de Lyon dans la Carte archéologique nationale : une démarche au service de la recherche

Abstract

The Carte archéologique nationale (National Archaeological Map) is a digital inventory of archaeological heritage within French territory, under the responsibility of the Regional Directorates of Cultural Affairs (Direction Régionale des Affaires Culturelles: Drac) –and their Regional Archaeological Services (Services Régionaux de l’Archéologie: SRA). Managed by the Ministry of Culture, this inventory is linked both to a database called Patriarche, and to a GIS (Geographic Information System) providing the geographical location of the data. The Patriarche database is enriched mainly through the analysis of all the available archaeological reports (filed subsequent to completion of their related excavations), diagnostic operations and surveys prescribed by the SRA. For the former Rhône-Alpes region (Centre-Est of France), Patriarche currently includes 47,405 sites –called archaeological entities (EA)–, for an area that represents 12 departments and one metropolis.The database integrates a wide range of information, such as the types of remains, their chronology, the related artefacts, as well as information regarding context, operations, sources and protection. In total, Patriarche contains more than 500 archaeological features related to the aqueducts of the city of Lyon.Until now, only factual elements based on archaeological operation results were integrated into the National Archaeological Map. Results also mentioned by the archaeologist in the report , but based on broader reflection were not taken into account, even if they were crucial to understanding the aqueduct layouts.Accordingly, the person in charge of the Archaeological Map for the area in question undertook –in collaboration with Catherine Coquidé until 2015– the verification and enrichment of the data concerning the aqueducts of Lyon.This work, consisting of combining and analysing data related to the aqueducts, made it possible to verify the 475 archaeological entities known as "aqueducts" present in the Patriarche database. More precisely, the verification of an archaeological entity requires one to return to the original sources, the archaeological reports, inventories, or any other document, such as maps or other elements that would be archived within the SRA centre. The site is subsequently geolocated as accurately as possible on the land registry.This revision effort was carried out for the 180 archaeological operations related to four aqueducts, which were then integrated into the Patriarche database. It was found that almost 44% of the archaeological operations prescribed for the presumed presence of an aqueduct turned out to be “negative” in the archaeological sense, meaning no remains of the aqueduct in question were identified. This high percentage demonstrates that the knowledge of aqueducts’ layouts is still very partial and dispersed.This reconsideration of the data has enabled the SRA to acquire the general layouts for the four main aqueducts of Lyon, which are being updated as operations and archaeological research continues to progress. These new layouts allowed the SRA to be more efficient in the management of archaeological diagnostic surveys for the areas concerned by the aqueducts.Of the 52 communes concerned by Lyon’s aqueducts, only 22 have a so-called “Zone de Présomption de Prescription Archéologique (ZPPA)” which refers to a presumptive zone of archaeological preservation, directly linked to at least one aqueduct, and ten more ZPPA are currently being drafted. It is through these decrees that the majority of urban planning files reach the SRA and provide the opportunity to prescribe archaeological diagnostic surveys.The verification of aqueduct layouts allowed for the revision of 15 ZPPA “aqueduct”, which have been effective since 2016. This work now ensures better protection of this linear layout through more a precise targeting of archaeological operation prescriptions, which in turn engender improved knowledge of these vestiges.By changing the geometry of a ZPPA which has already been revised, new archaeological diagnostic surveys may thus also lead to changes, again related to the layout of the aqueduct. These cases are difficult for the SRA to handle, as the ZPPA decrees –weighty in their application–, cannot be repeatedly modified.Although the Archaeological National Map and the Regional Archaeological Service are at the centre of the inventory work related to the aqueducts of Lyon, the Map can only be enriched in collaboration with the entire scientific community. This cooperation leads to permanent revision of Lyon’s aqueducts layouts and of the archaeological knowledge of these remains in general.