Water Science and Technology: Water Supply The hydraulic system of Bracara Augusta (Braga, Portugal). Discussing the archaeological and environmental heritage. --Manuscript Draft-- Manuscript Number: Full Title: The hydraulic system of Bracara Augusta (Braga, Portugal). Discussing the archaeological and environmental heritage. Article Type: Research Paper (Editorial Office Upload) Section/Category: Water Resources (including Groundwater and Reservoir Management) Keywords: Water management; Roman hydraulic systems; Bracara Augusta; water resources; archaeological heritage Corresponding Author: M. Martins PORTUGAL Corresponding Author Secondary Information: Corresponding Author's Institution: Corresponding Author's Secondary Institution: First Author: M. Martins First Author Secondary Information: Order of Authors: M. Martins J. Meireles M. C. Ribeiro F. Magalhães C. Braga Order of Authors Secondary Information: Manuscript Region of Origin: PORTUGAL Abstract: This paper gives notice of several archaeological remains related with the hydraulic system of the Roman city of Bracara Augusta recovered in the excavations of Braga during the last 40 years. The available data is presented in accordance with its functionality, highlighting the supply and distribution of fresh water and drainage of wastewater. In view of the known remains concerning the different thermal facilities of the city, as well as the evidenced distribution of water by gravity, through underground aqueducts and by pressure, through ceramics and lead pipes it is discussed the best plausible areas of water capture in the surroundings of the city. Based on the geomorphological and hydrogeological framework of Braga region, as well as on the analysis of the written sources indicating continuing channeling of water from the sedimentary basin of Sete Fontes, from the fifteenth century onwards it is concluded that it should also had been the primary place of water catchment during Roman times, conducted to the city by an aqueduct. Suggested Reviewers: Powered by Edit orial Manager® and ProduXion Manager® from Aries Syst em s Corporat ion Manuscript 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 Click here to download Manuscript PAPER_ID_77.docx The hydraulic system of Bracara Augusta (Braga, Portugal). Discussing the archaeological and environmental heritage. M. Martins1, J. Meireles2, M. C. Ribeiro3, F. Magalhães4, C. Braga5 Lab2PT (Landscapes, Heritage and Territory Laboratory), University of Minho, Azurém, 4800-058 Guimarães, Portugal (E-mail: mmmartins@uaum.uminho.pt) (E-mail: jmeireles@uaum.uminho.pt) 3 (E-mail: mcribeiro@uaum.uminho.pt) 4 (E-mail: fernanda.epmagalhaes@gmail.com) 5 (E-mail: cristina_arqueo@hotmail.com) 1 2 Abstract This paper gives notice of several archaeological remains related with the hydraulic system of the Roman city of Bracara Augusta recovered in the excavations of Braga during the last 40 years. The available data is presented in accordance with its functionality, highlighting the supply and distribution of fresh water and drainage of wastewater. In view of the known remains concerning the different thermal facilities of the city, as well as the evidenced distribution of water by gravity, through underground aqueducts and by pressure, through ceramics and lead pipes it is discussed the best plausible areas of water capture in the surroundings of the city. Based on the geomorphological and hydrogeological framework of Braga region, as well as on the analysis of the written sources indicating continuing channeling of water from the sedimentary basin of Sete Fontes, from the fifteenth century onwards it is concluded that it should also had been the primary place of water catchment during Roman times, conducted to the city by an aqueduct. Keywords Water management; Roman hydraulic systems; Bracara Augusta; water resources; archaeological heritage INTRODUCTION The last decades have witnessed a renewed interest over the existence of water in the Roman world, a likely consequence of a growing conscience related with the challenges impacting upon this precious resource in present days, in addition to an undeniable accumulation of archaeological remains emerging from excavations conducted in different regions of the Roman Empire. Despite the fact that approaches related with the supply and distribution of water in the Roman world have a long research history that is mainly associated with the technical aspects of the overall functioning of its hydraulic system, referred to in the works of Vitruvius, Pliny the Elder and Frontinus (Bonnin, 1984; Hodge, 1991), or is connected with the social aspects of its use, also well documented by the literary sources (Malissard, 1994:12), it is in fact the archaeological sources that provide us with a more general idea related with the way different regions of the Empire managed and used water, adapted it to the new technologies and new consumption habits. Although the vast majority of water sources supplying cities normally originated within each respective territory, it is unquestionably that the better part of material evidence is concentrated in the urban centres and can actually exemplify the way the Romans related with this resource. For this reason, cities perform privileged locations in the analysis of the importance of water and in the way it was managed; equally shedding some light over the changes related with its use on behalf of the indigenous communities integrated in the Empire. Thus, a great part of the public infra1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 structures preserved in Roman cities are directly or indirectly related with water, testifying the concerns about its supply and regular distribution, its social and cultural use and demonstrates that the management of water performed one of the main challenges faced by the overall organization of the urban centres (Landels, 2000:34). The study of the hydric supply in Roman cities represents a complex research subject, as each city performs a particular case study, given the particularities of every single respective geographical context that needs to be conveniently analysed. On the other hand, if the issues related with the supply and distribution of water require a specific knowledge related with the Roman hydraulic engineering techniques Fortes 2008) that were clearly adapted to the resources of each city, the ones related with its social use demand an approach focused on the infra-structures through which water was distributed to the population and to the buildings where it was consumed (Mar, López and Piñol eds., 1993). This was the approach we sought to follow, having as our case study the Roman city of Bracara Augusta and the results of the archaeological excavations conducted in Braga throughout the past 40 years. Available data represented by the remains of the aqueducts, pipelines, tubes, fountains and sewers are frequently difficult to interpret and fail to provide us with a systematic approach of the overall functioning of the hydraulic system. However, they reveal suggestive indicators related with the way water was managed and used in this Roman city, founded between the years 16/15 BC. On the other hand, and considering the number of thermal buildings identified in Braga that justify the existence of water catchment within the territory, a detailed analysis of the hydric potentialities within the city surroundings was rehearsed, aiming at clarifying which sites had the broadest potential for the water supply of the urban centre. Figure 1. Location of Bracara Augusta in the context of Roman Hispania. METHODOLOGY The many dozens of excavations conducted in Braga since 1976 enabled the accumulation of a wide group of evidences that provided a preliminary assessment of the different Roman structures associated with water management and reflect its use in the different public and private contexts (Ribeiro, 2010; Magalhães, 2010). They are equally suggestive of the overall functioning of the urban hydraulic system (supply, distribution and drainage) (Teixeira, 2012; Martins and Ribeiro, 2012). This first reflection, essentially focused on archaeological information, has been broadened under the Water Shapes Project, financed by the 2010 Culture Program. The conducted research 2 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 focused on two different complementary goals. The first one encompassed a systematic inventory associated with urban water infrastructures connected with distribution and drainage and the equipment attesting the different uses of water. This assessment provided data related with the Roman hydraulic system and the importance of water in social and cultural contexts. The second goal concerned the study of the topographic and geo-hydrological framing of the city and its respective surrounding region, in order to assess the potential water resources that could have been explored in Roman times. The used methodology contemplated the analysis and the interpretation of the archaeological remains associated with water, the detailed assessment of topography and the hydric potential of the Braga region, as well as, a diachronic approach focused on the water supply system in the subsequent periods to the Roman occupation. In this analysis, archaeological data, written sources and available iconographic data were contemplated, alongside referenced cartography Martins et al., 2011; 2012a; 2012b). ARCHAELOGICAL DATA Water supply Although rainwater performed an important supply source in Roman times the water collection was mainly cached from natural springs that flow underground or profoundly, or through dams and reservoirs (saepti), being backwater conducted through aqueducts (Fortes, 2008:45). Water provision of the cities sometimes included the three types of catchment. The collection of rainwater is well documented through the tanks existing in practically every excavated open area inside the Roman houses, normally located at the peristyles and atriums and used for irrigation and washing. The capture of underground water is also very frequent and is represented by wells (putei) (Gonzaléz Tascón and Velásquez, 2005:338; Fortes, 2008:96). In Braga the supply of water through wells is well documented throughout all the urban area (Martins and Delgado, 1989-90:26). The best-known examples, from a total of 11, are integrated in domus and artisanal establishments and show similar features and chronologies, dating back to the Flavian times. With variable depths, they have around 0.90 m of inner diameter (Martins, 1997-98). Until present day, only one fountain has been referenced to exist Braga. Its origin is believed to be pre-Roman and the site is dedicated to the Nabia goddess, which has a well-documented association to water and fertility. Located on an urban peripheral area, the fountain/sanctuary was the object of a monumentalizing process dated from the early city occupation and is signalled by sculptures and inscriptions that were surrounded by a granitic masonry wall (Elena et al., 2008). The fountain water came from a spring and its source was probably significant, considering that in the Flavian era the monument endured a small remodelling process that contemplated the construction of a tank. Its water probably supplied an associated bathing complex identified in the Granjinhos area, and located on the southern part of the fountain. The scarce available data related with the water supply within the city, as well as the data referring to the different distribution systems point towards the existence of a regular catchment of water outside the city, which must have been conducted through aqueducts. This hypothesis will be discussed further on. Water distribution The first piece of evidence related with an underground aqueduct responsible for the distribution of water was found in 1977 on the northern limit of the upper platform of the Alto da Cividade hill 3 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 (Figure 2a). With walls of regular blocks, based on a ballast of bricks and covered by large stone slabs, this conduct presented a specus with around 0.60 m high by 0.45 m width, which clearly demonstrated the importance of its water flow rate (Teixeira, 2012:sheet 68). Nearly 20 years later, between 2005 and 2006, when the excavation of the area located on the eastern and northern part of the theatre perimeter wall was being conducted, a southern extension of the referred aqueduct was identified, which enabled the establishment of its relationship with the water supply of the Alto da Cividade public thermal building (Figure 2 b) (Martins et al., 2011; Martins and Ribeiro, 2012). The structure had its ballast and walls coated in opus signinum (Figure 2 c) and revealed a slight N/S inclination (0.10 m in around 60 m extension). The association of this aqueduct with the water supply of the thermal complex enabled the assumption that it was likely a derivation of another and more important structure, which had to cross the city following an E/W orientation. Further, we believe that it may also have supplied the thermal building complex identified in the archaeological area located in Afonso Henriques street (Martins et al., 2014; Martins, 2015). Until now it was not possible to document this main aqueduct. However its existence seems to be documented by the water supply of the aforementioned thermal complex, running under a street located on the southern part of the building (Figure 6 c). Under these circumstances, we are led to believe that this underground aqueduct was likely one of the main water distribution structures existing in the city and probably running under the northern part of the forum and the decumanus maximus. Figure 2. Water supply aqueduct of Alto da Cividade thermae: (a) and (b) Aspects of the aqueduct. (c) interior view of the aqueduct coated with opus signinum. Besides than water distribution channelled by the aqueducts, where the water ran by gravity, other hydraulic remains associated with the distribution of water have been documented and are suggestive of its circulation by pressure in some parts of the city. This type of conduction seems to be corroborated by the finding of perforated syphon blocks (Teixeira, 2012), found in several parts of the city (Figure 3 a) and recommended by Vitruvius as the best way to overcome the valleys (VIII, 6.4.6). The inverted syphon technology is well known (Hodge, 1992) and we are aware that it has been largely adopted in the construction of several Hispanic aqueducts (Bonnin, 1984:179-219). Inside the syphon blocks, water was channelled through several types of ceramic or led pipes, being the latter the most recommended material due to its durability. However, the ceramic tubuli and the led fistulae were widely and independently used in the distribution of water. They existed in the shape of cylinders and had male/female ends (Figure 3 b), which ensured the tight nature of the pipes also guaranteed by the application in the joints of a quicklime mortar mashed with olive oil (Vitrúvio, VIII, VI, 8). A few of these ceramic pipes have been uncovered in Braga mainly associated with the water distribution to the thermal complexes (Teixeira, 2012: sheet 9; Ribeiro, 2010:414). The identification of a led pipe (fistula) in the excavations conducted in the Carvalheiras archaeological area, associated with the construction of a balnea (Figure 3 c), clearly demonstrates that this type of material was equally adopted in the water distribution network of Bracara Augusta, 4 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 similarly to what happens in other Hispanic cities (Bonnin, 1984:157). The uncovered fistula presented on its wider part a section measuring 141 mm in its horizontal axe and 146 mm vertically also exhibiting signs of welding on the edges (Martins, 2011:85-86). The pipe diameter enabled its classification as a wide size structure, included in the quinquagenaria type (148 mm diameter) (Adam, 1995:275). Figure 3. Elements of water distribution: (a) Perforated block of siphon, (b) ceramic pipe, (c) lead pipe (fistula aquaria). The water distribution supplying the public fountains existing in the city is still unknown, although it is possible to admit that the water was likely channelled in ceramic or led pipes running underground, exactly as it occurred in the city of Pompeii, where a complex distribution network existed running to 0.60 m deep and supplied around 40 public fountains (Eschebach, 1996; Jansen, 2001). The need for this type of structure was paramount in any Roman town as it was responsible for the supply of water for the majority of the urban population. The little evidence existing regarding this type of element results from its posterior reuse for other purposes, with the led pipes being likely melted in Late Antiquity. Water drainage The salubriousness and wellbeing of cities (salubritas civitatum), mainly in terms of cities founded ex novo during the Imperial era, demanded they had a wastewater drainage system. Its evacuation was assured by a group of conduits that eliminated the excess of rainwater and dirt water coming from the buildings and channelled towards central collectors that ran underground and drained it outside the urban area (Jansen, 2000:37-49). These sewages had visitation points and likely had some kind of inclination ensuring the disposal of wastewater. Several remains of conduits have been uncovered in Bracara Augusta, both associated with the drainage of rainwater and dirt water coming from buildings and channelled in infrastructures that circulated underground (Teixeira, 2012). Furthermore, the existence of a drainage system for residual and dirty waters has been attested by the existence of a wide cloaca running under the northern part of the cardus maximus (Figure 4) and identified in several archaeological excavations (Lemos and Leite, 2000; Martins and Ribeiro, 2012). This structure is believed to have been constructed in the mid first century and likely performed an answer to the consolidation of the foundational Roman urbanism, represented by the construction of the domus occupying both sides of this main axis of the city dated back to the Flavian period (Martins et al., 2012). This major collector was built with walls in granitic masonry and based over a ballast of granite slabs. Identified over an extension of around 50 m this structure presents a wider base (0.90 m) than the top (0.70m) and registers a height of 1.50 m (Teixeira, 2012) (Figure 4 b). Its coverage was made of granite slabs, over which seated a thick layer of very compacted granitic mortar. On the cloaca walls, seven holes in quadrangular shape were opened, measuring around 0.20 m on the side. They 5 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 reveal regular intervals ensuring the outflow of rainwater from the drains located in the bordering street areas and eliminated the excess water which percolated underground. The cloaca follows the street pending and is associated to other smaller collectors running under the decumanus that drained water from houses and other buildings. It has been possible to observe the connection between the cloaca and two other smaller sewers one of which identified over an extension of 30 m. Figure 4. Roman cloaca under the cardus maximus: (a) Part of the interior of the structure, (b) section. Despite the management of wastewater in Roman times performing a more recent research than the one related with the water supply it is key to highlight its relevance, as well as the significant accumulation of evidence provided by archaeology, which has allowed the recent subject approaches (Dupré and Remolà, 2008; Remolà and Acero Pérez, 2011). DISCUSSION Archaeological remains known in Braga reveal that Bracara Augusta benefited from a complex hydraulic system, a common feature present in all planned Roman cities. However, it should be emphasized that the fragmented character of remains resulting from urban archaeology only sheds some light over a few features of this system. Thus, available elements related with the distribution and the drainage systems already include a vast array of data suggestive of the existence of hydraulic networks for these two types of water (Teixeira, 2012), whose knowledge shall surely be further developed with the continuity of the excavations. A few items related with water supply are also known and are represented by tanks, wells and a fountain/sanctuary. Nevertheless, the scarce data related with the supply of the water necessary to guarantee the daily functioning of the city and mainly the thermal equipment already identified raised a fundamental question linked with available water resources in the territory. Notwithstanding the use of local groundwater collected by wells and supplying fountains we are sure that it was not enough to fulfil the clean water needs of Bracara Augusta which reached a considerable scale and had many public and private baths after the 2nd century onwards (Martins, 2005:70-72; Martins et al., 2011; Martins, 2015). On the other hand, archaeological evidences associated with the regular water supply of thermal buildings enabled the assumption over the existence of water cached outside the city. Water would circulate in one or more aqueducts that must have channelled it into castellum divisorium, an equipment that functioned as a distributor point (erogatio aquarum) and diverted the resource towards different destinations (Hodge, 1991:174). Through the conduits, running underground, part of the water was certainly destined to supply the thermal structures, while another part must have fed the public fountains network. A remaining part of the aqueduct water could have been destined for private houses (Fortes, 2008:72). One of these conducts likely crossed the city and followed an E/W orientation, ensuring the supply of the public baths, with a recognized derivation aqueduct that supplied the Alto Cividade thermal complex (Figure 2). 6 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 The lack of physical evidence related with a Roman aqueduct originating in the Ave river, located at around 24 km from Braga and suggested by several authors (Cunha, 1634; Leal, 1873; Morais, 2004), alongside the fact that the medieval and modern cities were supplied by the ‘Sete Fontes’ sedimentary basin (Ribeiro and Martins, 2012), has demanded a detailed analysis of the geomorphological and hydrogeological framework of Braga region in order to understand its potential and the suggestion of a sustainable hypothesis for the water supply of the Roman city. The Roman city occupied a rather privileged topographic location, on a flattened hill with 199 m high. This hill is the last elevation of a succession of secondary relieves starting at the ‘Serra do Carvalho’ (479 m) and gradually diminishing their altitude towards the west. Such relieves are represented by the northern foothills of that particular mountain, which dominates the Este river valley on the northern side and establishes the dividing line signalling the physical boundary existing between the ‘Cávado’ and ‘Ave’ rivers’ basins, with its lowlands almost reaching the city. On the southern side runs the Este River and its affluent, known as ‘Ribeira da Veiga’. From a geological point of view, both the urban and peri-urban space lay on the top of hircine granitic rocks, the so-called Braga granite. On the northeast side, these crystalline terrains are joined by a group of meta-sedimentary formations dating back to the Palaeozoic Age, in which another granitic rock, called ‘Sameiro’ granite, fits in (Ferreira et al., 2000: 8). Furthermore, this eastern city area corresponds to an area delimited by plentiful lithological contacts, to which a rather wide fraction is associated, running NNW-SSE, ENE-WSW and NW-SE. The latter direction represents an important structural decline that is part of the ‘Vigo-Régua’ shear fracture (Ferreira et al., 2000:41-42). (Sheet5D). Figure 5. (a) Topography and hydrology of Braga region. (b) Braga and ‘Sete Fontes’ area. Geological map In terms of its hydro-climatic record, the region of Braga registers a high annual rainfall (1515 millimetres), with average levels of evapotranspiration rounding 511 millimetres per year. However, a large part of that rainfall water is lost on the superficial drainage, being the percentage of retained water of around 1.3% (Ferreira et al., 2000:44-45). The granites from the Braga region also present an average to low or extremely low permeability (0,3 1/s), events only different in areas with an intense substrate fraction and alteration, or several lithological connections. Within this context, it is possible to observe productivities of around 2 to 3 1/s per square mile (Ferreira et al., 2000: 46), circumstances occurring in the area known as the ‘Sete Fontes’ basin, which reveals several lithological contacts, ranging from meta-sedimentary formations to seated granite rocks, with a high level of substrate fracturing. In this sense, the hydro geological features of this area are 7 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 highly favourable to both water infiltration and aquifer feeding, being the latter formed on top of hard rocks prompting the formation of natural water springs. The meta-sedimentary basin of ‘Sete Fontes’, located at around 5 kilometres from the city, is surrounded by a group of small relieves located at around 300 m from where the water capture would happen, most likely directly from the aquifers, which fed and still feed the ‘Sete Fontes’ modern aqueduct. This aqueduct was responsible for the water supply to Braga until 1929, remaining partially functional nowadays. Considering the topography of the city surrounding area, with particular emphasis towards the ‘Sete Fontes’ hydro-geological basin features, we believe that this refers to the area presenting the prime conditions to supply the Roman city through an aqueduct. Furthermore, the importance of the site as a water capture area is well documented from late fifteenth century onwards (Marques 1980:127-138). Braga endured several water supply challenges in different times, which are referred to in historical documentation from the fourteen hundreds, in a time when the city was substantially smaller than Bracara Augusta, even if we only consider the area inside the Low Empire wall, with around 48 ha. The fifteenth century reference pointed out the existence of pipes transporting water to Braga and supplying fountains and tanks, suggesting the existence of collection points outside the city, which can be traced back to earlier periods, including the Roman times. The relevance of the ‘Sete Fontes’ bassin as a hydric supplier site in Braga outskirts (about 5 km from the city) is equally documented in written sources from the seventeenth and eighteenth centuries that revealed that from 1670 onwards the city was supplied with water that was cached in ‘Sete Fontes’, ‘Passos’, ‘Areal’ and ‘Montariol’ sites (Oliveira, 2001:175). There are also references from the year 1737 related with the purchase of land with water at the ‘Passos’ and ‘Sete Fontes’ sites and others referring water springs in ‘Gualtar’ (Oliveira, 2001:178), alongside the purchase of water coming from ‘Montariol’. Apparently, the search for locations with water collection points throughout the eighteenth century was mainly focused on the ‘Sete Fontes’ bassin, although water springs had also been identified in Gualtar. Similar to the Modern Age, it is likely that the water catchment points during Roman times must have been diverse and that these might include ‘Gualtar’ site, as suggested by the remains uncovered in 2005 at the University of Minho campus. These remains documented the existence of a Roman aqueduct, observed over an extension of 91.5 m length and revealing stonewalls, brick ballast and a coverage organized with wide granite slabs (Braga and Pacheco, 2006). However, considering the rare and truncated character of this aqueduct remains it has been impossible to establish any articulation of this structure with the overall city water supply system. According with available data we believe that the water sources needed for the functioning of the Roman city must have been collected from the ‘Sete Fontes’ basin, channelled through an aqueduct with a path that must have matched nearly the trajectory of the modern one, a structure still functioning (Figure 6). We are aware that this aqueduct that supplied Braga from the fourteen hundreds onwards and was successively improved over the centuries has fossilized the trajectory of a Roman road connecting Bracara and Asturica Augusta (via XVIII). Between 2013 and 2014, the Unit of Archaeology had the opportunity of studying in detail the ‘Sete Fontes’ modern aqueduct. Although this study failed to document any preserved Roman elements it does not invalidate the hypothesis that the water supply in Bracara Augusta was channelled from water sources existing in the area. In fact, the well documented systematic search for water on the ‘Sete Fontes’ bassin throughout the historical times, together with the hydrogeological features of 8 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 this area, represent arguments favouring that hypothesis, appearing unlikely that the hydric potential of this area has eluded the heads of the Roman city. Figure 6. Reconstruction of the path of the Roman aqueduct: (a) capture area, (b) aqueduct, (c) Roman city and distribution of water to the public baths (Carthography - Sheets 56-70 ot CMP, 1:25000). CONCLUSION Archaeological data presented and discussed in the present paper, although perhaps still insufficient for a thorough study of Bracara Augusta’s hydraulic system, is rather suggestive of the way the Roman city related itself with water, both in terms of the structures ensuring its supply, distribution and drainage and in terms of its social and cultural use. Equally, archaeological data points towards the possibility of the city had the need to collect water from the surrounding region, a circumstance that was occurred in other more recent historical periods. On the other hand, the topographic and geological features of the Braga region underline the particular potential of the ‘Sete Fontes’ basin as the hydric supplier of the town, as referred to in written sources from the fourteen hundreds onwards. In fact, we consider that this was the most probable area as the prime water collection point to supply the Roman city. In addition, we believe that the catchment of water from the ‘Sete Fontes’ basin represents a common thread connecting different occupational periods of Braga, as the site has likely supplied the successive urban centres throughout the ages, which also demonstrates the existing millenary knowledge related with the hydric potential of the territory. ACKNOWLEDGMENTS This work has the financial support of the Project Lab2PT - Landscapes, Heritage and Territory laboratory AUR/04509 and FCT through national funds and when applicable of the FEDER co-financing, in the aim of the new partnership agreement PT2020 and COMPETE2020 - POCI 01 0145 FEDER 007528. REFERENCES Adam, J. P. 1994 Roman Building. Materials and Techniques. R. T. Batsford Ltd, London, UK. Bonnin, J. 1984 L’eau dans l’antiquité. L’hydraulique avant notre ère (The water in antiquity. Hydraulic before our era). Editions Eyrolles, Paris, France. Braga, C. and Pacheco, J. 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