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BY 4.0 license Open Access Published by De Gruyter Open Access August 10, 2023

New Insights Into the Water Management System at Tetzcotzinco, Mexico

  • Daniel Prusaczyk EMAIL logo , Karolina Juszczyk and Araceli Rojas Martínez Gracida
From the journal Open Archaeology


This work presents the results of new archaeological research carried out in Tetzcotzinco, Mexico, with a special focus on its water management. Survey documentation at the site, with the use of 3D photogrammetry, offered new images and maps of water control features, namely, canals, reservoirs, and aqueducts. The integration of these data into a GIS database, as well as the complementation of information from previous archaeological research and colonial historical accounts, allowed further analysis of the flow, velocity, and quantity of water distributed at the site, and its possible connections with watercourses in its surroundings. This research studies the broader regional water sources and three possible courses of water in the area which could have provided the flow of liquid into Tetzcotzinco. This article is a contribution to a better understanding of the importance of water and its distribution not only in Tetzcotzinco but also in the Center of Mexico during pre-Hispanic times.

1 Introduction

Water played a central role in the life of the ancient Mesoamerican people. Access to fresh water, its control, and distribution were fundamental for the development and growth of cultures. Water was essential for the success of agriculture and therefore became a key matter for the economy and political relations. At the same time, water was a sacred entity, a constant recipient of offerings in religious acts. The enormous importance of water for every Mesoamerican community, its significance and, in particular, the techniques of its acquirement and storage in ancient cultures were the subject of scholars’ interest for decades. Admittedly, this topic is currently best recognized within the Olmec (e.g., Coe, 1968; Cyphers & Zurita-Noguera, 2006) and the Mayan cultures (e.g., Chase & Cesaretti, 2018; Scarborough, 1998; Šprajc et al., 2021; Valdés, 2006) or in the areas of the states of Puebla and Oaxaca (e.g., Hopkins, 1984; Kirkby, 1973; Woodbury & Neely, 1972). However, similar issues for Central Mexico, especially studies based on archaeological research, are still overlooked in the academic literature.

In the Center of Mexico, at the Basin of Mexico, different communities developed various strategies for obtaining and controlling water over centuries of cultural development. The significance of such techniques and engineering is still not completely understood in the pre-colonial history of this region. The reason is the small amount of preserved remains of water control technologies and few numbers of historical sources devoted to this issue. However, there is one Mexican site that has survived with astounding well-preserved and complex canals and a water reservoir system: Tetzcotzinco. Despite its importance as a water distribution center, due to the lack of appropriate research methods and insufficiently developed documentation techniques, archaeologists have not been able to adequately reconstruct the course of Tetzcotzinco’s canals to understand how the system functioned. Only in recent years, as a result of a new, non-invasive documentation project in Tetzcotzinco, can we better understand the water control techniques developed by their builders and inhabitants, the Acolhuas[1].

The aim of this study is to present the results of this new research on the water management system both in Tetzcotzinco and in a broader regional context. The research investigates water control features at Tetzcotzinco, in particular canals, reservoirs, and aqueducts, which had previously been documented and published in the literature, as well as recent data recovered for this study using archaeometrical techniques. This documentation helped to elaborate new maps and images of the site, with particular emphasis on the visualization of the water management system. This visualization was achieved through the creation of 3D models and GIS studies. This study also examines several previously unrecognized issues related to Tetzcotzinco’s water management system, such as the tracing of the watercourses at the site, the determination of the amount of water stored in local reservoirs, and the recreation of the approximate water flow velocity in subsequent sections of the entire system. These three following aspects constitute proposals that may well be subject to further scrutiny; additional geographical modeling and in situ information could aid to provide validation to these schemes in the future. Nonetheless, this comprehensive approach to the water control system at the site, particularly taking into account the archaeological and geographical data, has already advanced to acquire a better picture of Tetzcotzinco water flow and management.

Furthermore, the inclusion of the previously unknown external canal that surrounds the site, allowed us to explore the existence of a more extensive, regional water distribution system. Therefore, the research was extended to include geographic studies in a broader context, with the aim of preparing a hypothetical regional watercourse. The proposed models, in the form of maps, were developed based on information available from historical sources and previous archaeological investigations. The traced routes were integrated into GIS models and manually corrected by considering topographical, hydrological, and vegetation data. These models constitute only the formulation of a hypothesis regarding possible courses of water in the regional system of water sources and distribution. Further testing and validation require conducting additional archaeological prospection and studies in environmental and natural sciences, in particular, detailed investigation of geological and paleoclimatological features. Nevertheless, this research constitutes an important contribution to a better understanding of the pre-Hispanic water management system both in Tetzcotzinco and in the area of the eastern side of the Basin of Mexico and provides a solid basis for future research on this issue.

1.1 Background

Tetzcotzinco is one of the best-preserved sites with monumental architecture dating back to the Late Aztec Period (1400–1521 AD). The site is located east of present-day Mexico City, in the town of San Nicolás Tlaminca, municipality of Texcoco, State of Mexico (Figure 1), and is located on the hill of the same name. The archaeological park in Tetzcotzinco (Zona Arqueológica de Tetzcotzinco) was established in 2005 (Alcántara Onofre, 2002, pp. 52–53). Its boundaries also include the surrounding areas, including the nearby hill named Metecatl, together with the archaeological remains existing there (Lesbre, 2001, p. 325). This place is most often presented as the biggest pre-Hispanic palace-garden complex[2] in the Basin of Mexico (Evans, 2000, p. 212). Nowadays, only the ruins of residential and ceremonial buildings and hydraulic features carved in rock (such as reservoirs and canals) are still standing. There is also a well-preserved complex of sculptures and petroglyphs contemporary to the period of the palace-gardens. A significant group of this type of objects is the one depicting the models of architectural structures carved in the rocks located on Metecatl (Domínguez Nuñez, 2007, p. 84). The time of largest growth of Tetzcotzinco falls in the fifteenth century and the reign of Nezahualcoyotl (1431–1472). He is attributed for the design and construction of the royal “garden” and ceremonial center after he became the ruler of the capital of the Acolhuacan territory, part of the Aztec Triple Alliance at the eastern part of the Lake of Texcoco (Anales de Cuauhtitlan, 1975, pp. 40–41) (Figure 1).

Figure 1 
                  Tetzcotzinco archaeological site.
Figure 1

Tetzcotzinco archaeological site.

One of the most important projects of Nezahualcoyotl was the construction of a system for water management. It consisted mainly of a complex of canals and aqueducts leading fresh water from springs located around Mount Tlalocatepetl (Parsons, 1971, pp. 146–147). Archaeologists have also documented a system to control the quantity and speed of flowing water, as well as several water reservoirs, pointing out their religious significance in Tetzcotzinco (García García, 2007, pp. 136–204). No doubt the water management system had an important symbolic role, but the canals crossing the hills probably also played economic roles, supplying fresh water to farmlands and local settlements. Due to its location, hydraulic features, and historical sources, it has been suggested that the site was part of a regional network of canals connecting the most important cities throughout the Acolhuacan area (Barlow & McAfee, 1946, p. 110).

Tetzcotzinco’s monumentality has attracted scholars for decades. The first attempts to map the site were made at the turn of the 19th and 20th centuries when researchers prepared the first plans of Tetzcotzinco’s preserved architecture (Reyes, 1888, pp. 140–141; Mendizábal, 1946). In the subsequent decades, mainly thanks to the studies of Parsons (1971) and Townsend (1982), subsequent structures were discovered with new interpretations of their significance. The most extensive excavations so far, covering the central part of the site, were carried out by Hernández (1993) and García García (2007).

These studies have touched upon the water management system of the site. Parsons (1971, pp. 146–149) proposed new maps of canals based on the archaeological survey and studies of the local topography. This topic reached later discussions on Mesoamerican waterworks, like in the works of Palerm and Wolf (1955), Peña Santana, and Levi (1989, pp. 20–25). Particularly, the latter extended Parsons’ plans with aerial photos, and Doolittle (1990, pp. 127–135) and Rojas Rabiela, Martínez Ruiz, and Murillo Licea (2009, pp. 70–76) studied the construction of individual features of Tetzcotzinco’s water management system. Despite investigators’ interest in pre-Hispanic gardens in Mexico and their significant contribution to this field, there is still a lack of comprehensive and multifaceted research on Tetzcotzinco, primarily focused on the water management system, its construction, and its socio-economic importance.

2 Methods, Sources, and Techniques

In order to achieve a better understanding of Tetzcotzinco’s water management system, both within the site and partially reaching its broader geographical context, a considerable amount of data from different sources were collected, processed into a database, and recreated into maps and 3D models. The visualization of these data allowed the discussion of some previous assumptions on how water was controlled and where it came from.

One of the main sources for this research comes from the empirical data that were collected in 2018 during 1 month of fieldwork. In this survey, archaeological and constructive features at the site were documented with the aim of studying their functioning in the local water management system. To accomplish this, a detailed and complete archive and library query was also conducted. Maps, plans, and archaeological documentation of previous Tetzcotzinco researchers (Alcántara Onofre, 2002; Domínguez Nuñez, 2007; García García, 2007; Medina, 1997) were reviewed to create a basis for further analysis. To these data, the results of fieldwork were added, the most important of which were the features that qualified for “water management.” These included, partially or complete remains of reservoirs, canals (either excavated on the soil or recovered with plaster), aqueducts (usually bigger than canals and supported with stones and slabs to elevate them from the floor level), uneven floor levels (humanly made), and outlets (small drainage holes). The documentation of these features was carried out with three-dimensional scanning and modeling. Larger architectural features within structures, such as Aqueduct 1 and reservoirs inside buildings, were registered with 3D photogrammetry, using the scanner (FARO Focus) and complemented by GPS RTK measurements. The scans were supplemented by 3D models made with a camera in areas that the scanner’s range could not reach. The models were processed using 3D modeling software (CloudCompare 2.12.3, Faro Scene 2018.0.0.648, and Agisoft Photoscan Professional and graphic tools (AutoCAD 2022.2 v.S.52.M.35 and Photoshop CC 2014)[3]. With these techniques, features and structures (including primarily canals) were reproduced in 3D models which covered an area of almost 17,000 m2.

These new archaeological data were included in a GIS database (using QGIS software, version: 3.22.9 Białowieża), along with other information which came from bibliographical research (see challenges discussed in next section). Besides incorporating different types of data (graphics, 3D models, and text data), this database also made possible to handle the information with georeferences in a single space, allowing metrical analyses over large areas.

With this at hand, the study allowed for expanding the geographical scope to attempt a hypothetical recreation of the watercourses supplying water to Tetzcotzinco’s water management system. With the help of GIS data and the study of historical accounts (Barlow & McAfee, 1946, pp. 111–125), three water routes were created and shown in maps, which in the future can serve as a basis for building a more accurate model of such a regional water distribution system. This hydraulic analysis reached the northwestern slopes of the Tlalocatepetl-Telapon massif (approximately 8 km south of Tetzcotzinco), where the peak of Yeloxochitl is located (Figure 2). This hill was mentioned as a potential water source for aqueducts and canals leading northwards to Tetzcotzinco (Barlow & McAfee, 1946, p. 112) and close to the towns of Tlaixpan and Tlaminca. These communities in pre-Hispanic and probably colonial times were symbolically and economically connected with the site and the construction of its water management system (García García, 2007, p. 129).

Figure 2 
               Area of research, including the broader-regional water management systems and all locations mentioned in the text.
Figure 2

Area of research, including the broader-regional water management systems and all locations mentioned in the text.

Overall, considering the geographical, archaeological, and bibliographical information collected to build the GIS database, the area of analysis of the present study covers 84.5 km2, including the whole site of Tetzcotzinco and Metecatl hills, Tlaixpan and Tlaminca towns directly at the north, and the area immediately to the southeastern side, covering Santa Catarina del Monte and Texapo, until the skirts of the Mount Tlalocatepetl mountain or the Tlalocatepetl-Telapon massif, particularly the Yeloxochitl hill.

2.1 Important Considerations in the Bibliographical Sources Used

When filling in the GIS database (WGS 84 UTM 14N) with the geographical data coming from bibliographical sources, there were some challenges encountered that are worth explaining. First, each of the following sources was contrasted and complemented with digital satellite imagery (from Google Satellite) showing georeferenced topographical, hydrological, and urban features together with orthophotomaps with an accuracy of 0.5 and 1.5 m provided publicly by the Mexican National Institute of Statistics and Geography (INEGI, Another data that helped building the database came from digitizing historical maps of the area, which were consulted and photographed in situ in the Map Library Manuel Orozco y Berra in Mexico City. In this way, the trajectory of canals, aqueducts, and sources of fresh water, which were proposed decades before when digital visualization and modeling were not possible, was therefore corroborated as it will be shown further.

The first watercourse that was examined and integrated into the database comes from the investigations of Parsons (1971, pp. 145–147). This lies at the eastern side of the site, reaching contemporary Santa Catarina del Monte. During his studies in the Texcoco region, Parsons mapped the remains of pre-Hispanic aqueducts and contemporary canals in the area, combining them into a single system. According to him, the still-functioning rural canals, to a large extent, reflect the course of the old system. With this reconstruction, he proposed a route of canals that could have supplied Tetzcotzinco with water in the past (Parsons, 1971, p. 145). Nowadays, this map is the most widely acknowledged reconstruction of the water management system in the region (García García, 2007, p. 211; Medina, 1997, p. 69). Furthermore, Parsons located a possible water source for Tetzcotzinco in the spring of Texapo, south of the town of Santa Catarina del Monte (Parsons, 1971, p. 146). Based on his analyses, he traced a water route running northwards from the spring, passing through San Pablo Ixayoc and Tequexquinahuac, and eventually reaching Tetzcotzinco by supplying the Caño Quebrado (Figure 2).

Although Parsons’ proposal is widely recognized, it should be noted that there is no historical data that would indicate such a course of the canals in southern Acolhuacan. The spring of Texapo (or rather “Techapan”) itself has been mentioned as a source of water for the local community only since the eighteenth century (González Rodrigo, 2006, p. 28). Also, the survey conducted by Parsons himself did not confirm the increased settlement activity in this area in the Late Aztec Period (Parsons, 1971, p. 95). Therefore, due to the emerging doubts, the canal route proposed by the scholar was revisited and confronted with the natural, topographical conditions of this area provided by the georeferenced data in GIS.

As with Parson, also the investigations of Victor Arribalzaga Tobón (2005) were examined. His research proved the hypothesis concerning the existence of a network of roads and pilgrimage paths, connecting the most important settlements in Acolhuacan with the temples and shrines on the Tlalocatepetl range (Arribalzaga Tobón, 2005, p. 166). He conducted a series of analyses that allowed him to develop a hypothetical road system of the Texcoco region. Remarkably, when his data were considered for this research, a clear correlation between these roads and the routes of canals in the vicinity of Tetzcotzinco emerged visibly. It is important to mention that he did not take into account the possibility that the same paths could also be water channels. However, the coincidences were so clear that became logical to include his work in the following proposed reconstructions of the southern part of the regional water management system.

The proposal of paths of Arribalzaga constitutes a second possible water supply system for Tetzcotzinco, running along the northeastern road as mapped by the author. It begins at the peak of Tlalocatepetl and runs along its northern slope, connecting several minor archaeological sites, and, like in the Parsons’ system, passing through Santa Catarina del Monte and finally reaching the Caño Quebrado and Tetzcotzinco (Figure 2). The trajectory of this route, however, has been slightly altered so that watercourses could feasibly run following the natural shapes of the land. Worth reiterating, this suggested second water network was completed with the assumption that the route of pre-Hispanic roads (in particular, pilgrimage paths) largely overlapped with the course of canals and aqueducts. The analysis of the topographic layer, the contemporary hydrological network, as well as the archaeological findings in Tetzcotzinco and its vicinity and the mentions of canals connecting pre-Hispanic altars and places of worship in the historical accounts (Obregón, 2009, p. 11; Pomar, 1971[1891], p. 3) bring support to this assumption.

The third important source that allowed for new insights into water sources and courses in the Tetzcotzinco area was a colonial historical account known as Titulos de Tetzcotzinco (1999[1898]). This document, written in Nahuatl, describes alleged land rights to Tetzcotzinco and surrounding settlements. This type of manuscripts has been crucial in diverse and controversial land disputes in Mexico since the arrival of the Spaniards. However, Titulos de Tetzcotzinco stands out from other documents of this genre because it deals predominantly with water control and the system of canals connecting individual towns in the Texcoco region. Even though this document states a date of 1537, it is probably a copy; its style indicates more an eighteenth-century creation (A. Brylak and J. Madajczak, personal communication, January 2021). Despite the late origin of the document, it can be assumed that some of the information provided is a legacy of actual knowledge about the region from the early colonial times, and at least some of the canal routes mentioned in the text were still functioning at the time of Titulos’ creation. Therefore, this document is an important source of knowledge about local water distribution systems. Other historical sources that were useful for this study and which helped to complement the information in Titulos were Relación de Tetzcoco (Pomar, 1971[1891]), containing a description of the lands in the Texcoco region and Proceso Inquisitorial del cacique de Tetzcoco (Obregón, 2009) which mentions the pilgrimage system of Acolhuacan.

Although the Titulos text undoubtedly refers to the studied area, its descriptions do not faithfully reflect the topography of the site and therefore, when placing the location of the sites, in the GIS platform, they ended up inaccurate. To overcome this, all the toponyms in the Titulos document were listed and searched on the contemporary region, while looking at the only available data, namely, the topography and hydrology of the terrain and possible courses along which the canals could have been routed. At the same time, other archaeological data were considered, some already mentioned in this work (Blanton, 1975; Brumfiel, 2019; Charlton, 1973; Parsons, 1971; Parsons, Brumfiel, & Hodge, 1996; Sanders & Evans, 2000). Descriptions and maps of these scholars allowed for analysis of the settlement patterns, which in turn served for the reconstruction of this third possible regional canal network in the region.

The most important information provided by Titulos was the reference to the natural water source for the entire system. According to the document, it was placed in Yeloxochitla[n] in the southern Sierra (Titulos de Tetzcotzinco, 1999[1898], p. 1). In this way, the exact location of the hill, today called Cerro Yeloxochitl, was placed; in fact, the hydric-geographical layer confirms an existing water spring (INEGI, 2010). By following the descriptions of the document, the possible course of water canals was suggested, starting at the hill and running northwards through the places and toponyms mentioned in Titulos (including Quetzaltepec, Ixayoc, Xochimanca, and Metecatl), and finally connecting the natural water source with the system in Tetzcotzinco (Figure 2).

These three proposed watercourses, the canal plan proposed by Parsons, the maps done by Arribalzaga, and the route of canals of Titulos, constitute the basis for the formulation of hypotheses about the water control system in the broader regional context (Figures 1214). These projections were made manually, and the possible courses of canals were designed between the points mentioned in these sources, taking into account several geographical and topographical factors, namely, the elevation of the terrain, the slope of the land, the natural course of rivers and other waterways, dense forest cover, the openness of the land, and location of pre-Hispanic settlements and archaeological sites, that would potentially allow conducting such canals. The range of such features was also limited to the routes mentioned in historical sources (e.g., Titulos de Tetzcotzinco). As it will be shown further, the possibility of distributing water to downstream areas in the nearby valley, taking into account the water management system that was documented at the site, was taken into consideration. However, it is important to mention that there were variables that influence the capability and correct functioning of the proposed models which could not be part of this study. These variables include quantitative and qualitative data on soil permeability, seasonal precipitation, and groundwater status, just to name the most relevant. With these data, it could have been possible to run additional computational models in order to bring validation to the proposed water courses in this study. However, to obtain these data, interdisciplinary collaboration in the fields of geology, soil sciences, hydrogeology, and paleoclimatology is needed, requiring a detailed and financed research plan, perhaps even incorporating the sampling and testing on the field. For now, the proposed maps cannot be considered a definitive feasible outlook of the course of pre-Hispanic canals. Nevertheless, they constitute a first hypothetical approach, partially authenticated with historical, archaeological, and geographical data, aiming to advance in the viability of running water through the water management system at Tetzcotzinco and in its immediate regional area.

3 Results

These lines describe the recovered archaeological data on the site and the analysis of the water management both within and in the surroundings of Tetzcotzinco, including the water flow velocity, the volume capacity of reservoirs, and new findings on outlet-drainage, natural damage caused by water, and a whole new canal on the site, which probably was responsible for the distribution at a larger scale.

3.1 Water Management System Within the Site

Fieldwork allowed the documentation of all known archaeological structures and features at the site with particular attention to the remains of the water management system. The collected data led to metric three-dimensional models of this record (Figure 3), which constitute the basis for further analysis.

Figure 3 
                  3D models of the water management system’s structures with dimensions of the scanned area: (a) Reservoir 1; (b) Reservoir 2; (c) Reservoir 3; (d) Reservoir 4; (e) Structure 5; and (f) Aqueduct 1.
Figure 3

3D models of the water management system’s structures with dimensions of the scanned area: (a) Reservoir 1; (b) Reservoir 2; (c) Reservoir 3; (d) Reservoir 4; (e) Structure 5; and (f) Aqueduct 1.

The most impressive and well-known features of Tetzcotzinco’s water management system are monumental water reservoirs. Currently, three of these have been discovered on the hill of Tetzcotzinco (the so-called baños) and the one on Metecatl.

The largest reservoir is Reservoir 1 [4] (Figure 3a). It is located on the western slope of Tetzcotzinco, where it is connected with the canals surrounding the main path (Figure 4). It consists of the main reservoir and a terrace structure (García García, 2007, pp. 137–138). The reservoir itself has a circular shape and a floor made of a smooth, natural rock surface. In addition, the reservoir has a smaller, deeper pool carved into the floor. The walls of the reservoir were made of masonry and includes a staircase. Reservoir 1 is also connected with the terraced, three-level structure, probably used for ceremonial purposes. This structure was partitioned by a stone channel, which was formerly connected to the main canal accompanying the path. This channel brought water to the smaller pool that probably served as a filtration device and then filled the reservoir.

Figure 4 
                  Map of Tetzcotzinco showing archaeological structures and features.
Figure 4

Map of Tetzcotzinco showing archaeological structures and features.

The second scanned reservoir is Reservoir 2 [5] (Figure 3b). It is located approximately 120 m in a straight line from Reservoir 1 to the southeast, below the main path (Figure 4). The entire structure is intriguing due to the almost exclusive use of monolithic architecture. The reservoir was carved entirely in the bedrock and it is circular in shape. The inner surface of the reservoir was polished and, in the past, it was covered with multi-colored stucco (García García, 2007, p. 141). In the eastern part, the reservoir has carved steps leading to the interior of the structure. The small size of this reservoir and the seat carved inside the reservoir seem to indicate that it played a much more private role than Reservoir 1 and could have been used for ritual or recreational baths reserved exclusively for the ruler.

The most poorly preserved reservoir of this type is Reservoir 3 [6] (Figure 3c), which is located on the route of the northern path (Figure 4). It is also a feature entirely carved in the bedrock, protruding a few meters above the level of the path. The circular reservoir itself is the smallest one in Tetzcotzinco. The original and precise depth of the reservoir is hard to determine due to extensive destruction and erosion in this part of the site. There is also a small terrace carved around the reservoir, limited on the south side by a smooth, vertical rock wall. Due to the immense damage, understanding the purpose of Reservoir 3 is currently unattainable.

The last and also the second-largest monumental reservoir is Reservoir 4 [7] (Figure 3d), located on the hill of Metecatl (Figure 4). This feature was built inside a larger building which has been interpreted as a place of water flow control (García Garcia, 2007, pp. 215–216). The whole complex consists of two parts. The first, located on the eastern side, is formed by the housing area, composed of a building divided into three small rooms. The second part is a small platform made of masonry with a huge, circular water reservoir. This structure was the first place for water collection at the site and directed the water to the canals within the complex (Structure 5 [8]; Figure 3e).

Structure 5 is one of the most complex and least comprehended complexes of Tetzcotzinco’s water management system. It is located directly at the beginning of the main Aqueduct 1 [9] (Figure 3f), on the northern slope of Metecatl (Figure 4). This monumental structure covers an area of approximately 1,065 m2 and consists of seven terraces of various sizes. All terraces are connected by stairs and continuous channels with a rectangular cross-section that is then connected with the main Aqueduct 1. Three small water reservoirs have been documented within this complex, whose function is still not fully recognized. The first and the smallest reservoir is rectangular, while the two larger ones are in the form of low, circular pools. Moreover, it is possible that formerly there were buildings on some levels of Structure 5 terraces that have not survived to this day (García García, 2007, pp. 217–218).

Along with the documentation of the reservoirs, canals and aqueducts were also scanned. The largest of them is the main Aqueduct 1, which connects the hills of Metecatl and Tetzcotzinco (Figure 4). This structure is spread over a stone and earth mound, with a maximum height of 3 m, and slightly sloping sides in the form of a talud. The total length of the entire structure reaches 170 m, while the width at the base is about 3 m. Excavation studies have shown many phases of the construction of Aqueduct 1, which gradually raised and expanded in pre-Hispanic times. On the top of the mound, an open channel with a rectangular cross-section made with stone slabs and covered with stucco was documented.

Aqueduct 1 ends with a hydraulic “node” located near Structure 1. At this point, the water split into two small canals that circled the central part of the hill of Tetzcotzinco, along the main path, which ends in Reservoir 1. Depending on the section, this canal has a different form: an open canal sunk in the ground, a channel limited by low masonry walls, or a monolithic canal. Due to the form and length of this feature, its construction was documented with photogrammetry, which helped to recreate its course in a digital form.

3.2 WMS Archaeometrical Analyses

The obtained data, especially 3D models, were used for the analysis of the water management system in Tetzcotzinco. The high accuracy of the models up to 2 mm and the large size of the documented area (16,960 m2) allowed to carry out numerous studies in a digital way which not only provided high precision but also provided a faster and more accessible possibility to study architecture than traditional analyses conducted in situ.

One illustrative example that helped the reconstruction of the direction and technique of water distribution within the site was the analysis of height differences. To do this, multi-colored projections of buildings were generated in order to show height differences and surface anomalies both within structures and features. This enabled to observe differences in heights that suggest the direction of the water flow (Figure 5). On this basis, height measurements on individual sections were taken, for instance, the dimensions of canals were in this way obtained. In addition, this allowed the calculation of the water flow velocity at three stages of the system: on the hill of Metecatl, in Aqueduct 1, and in the main canal surrounding the hill of Tetzcotzinco. Determining the velocity of the flowing water can provide a wealth of information about the entire system. First of all, the connection of the water flow velocity with the natural topography of the hill may form the basis for a discussion on whether Tetzcotzinco was intentionally selected as the site for the construction of the water management system due to its natural form. Moreover, the information on approximate flow velocity can reveal parts of the entire system that were most exposed to erosion and damage from flowing water. Furthermore, this leads to finding spots where mechanisms were placed to control and slow down the water. Significant differences in velocity between the individual parts of the system also demonstrate the possible use of technologies for acceleration or deceleration of the flow (Farrington, 1980, pp. 290–292).

Figure 5 
                  Plan of Structure 5 with the gradient of height differences generated from the 3D model and the direction of water flow.
Figure 5

Plan of Structure 5 with the gradient of height differences generated from the 3D model and the direction of water flow.

The water velocity in Tetzcotzinco was determined based on the revised Gauckler–Manning formula of flow velocity for the open channels (Chanson, 2004, pp. 264–267):

v = 1 n R 2 3 I 1 2 .

This formula allows for determining the water velocity based on the values of the Gauckler–Manning coefficient (n), hydraulic radius (R), and hydraulic slope (I). The n coefficient provides information about the roughness and type of canal surface, thereby determining its construction’s influence on the water flow resistance. The hydraulic radius describes the size of the channel by the ratio of its cross-section area to the length of the cross-section perimeter. The hydraulic slope, in turn, determines the canal’s grade by the ratio of the drop-in elevation to the distance over which this drop occurred.

As a result of the measurements and calculations, the estimated velocity of water flow in the canals of Tetzcotzinco was determined. Of course, due to the condition of the water management system at the site and the varying dimensions of each canal (the width and depth of the canal vary between 1 and 5 cm at different sections), the given values are averaged and approximated and the actual speed could slightly differ from given values (Table 1). Due to the non-invasive nature of this project, it was not possible to perform physicochemical analyzes of the canal surfaces that would have allowed determining the type of material used in the construction of particular features and their roughness. These data could have allowed a better identification of the n coefficient for the calculations. In view of this limited in situ observations, this study adopted a coefficient of 0.02 which corresponds to stone, loess, or clay surfaces that appear to be most similar to the material of Tetzcotzinco’s canals (Chanson, 2004, p. 79).

Table 1

Estimated velocity of water flow at the site

Measuring point Distance to next measured point (m) Height above sea level (m) Hydraulic slope Cross-sectional area (m2) Wetted perimeter (m) Hydraulic radius Average velocity of flow (m/s) Critical flow
F1 24.05 2429.63 0.0875 0.95 0.092 3.84 2,238
F2 7.11 2425.52 0.1712 0.05 0.65 0.077
F3 13.54 2424.41 0.159 0.105 0.95 0.11
F4 2422.98 0.1052 0.105 0.95 0.11
Aqueduct 1
A1 114 2510.75 0.0114 0.0625 0.75 0.0833 1.02 0.651
A2 2509.43
Main Canal (Tetzcotzinco)
C1 9.55 2510.02 0.06 1 0.060 0.85 0.459
C2 6.24 2510.17 0.016 0.086 1.26 0.068
C3 2510.27 0.016 0.111 1.34 0.083
C4 7.57 2511.91 0.091 1.31 0.069
C5 8.67 2511.96 0.007 0.1032 1.432 0.072
C6 2512.15 0.022 0.0665 1.08 0.062
C7 13.59 2512.17 0.078 1.124 0.069
C8 9.07 2512.10 0.005 0.1 1.4 0.071
C9 2512.07 0.002 0.105 1.3 0.081
C10 10.7 2512.09 0.0875 1.2 0.073
C11 26.46 2512.12 0.002 0.086 1.26 0.068
C12 2512.69 0.023 0.105 1.34 0.078

Achieved results show a gradual decrease in the speed of the water within the site from about 3 m/s on the hill of Metecatl to about 0.8 m/s along the main path on Tetzcotzinco. The obtained values seem to correspond to the natural slopes of the terrain at the height of the main path of the site. Hence, this seems to confirm the hypothesis about the intentional choice of Tetzcotzinco as a place of water distribution. Changes in the height of the terrain along which canals had been led enabled control of the flow of water, which was supposed to reach the lowest speed in the central part of the site and slowly feed the most important reservoirs. Beyond the hill of Tetzcotzinco, significant differences are visible, primarily in the place between Aqueduct 1 and the main canal, where the hydraulic “node” likely played a role in slowing down the water. The above results indicate remarkable changes in water velocity in subsequent sections of the system, especially between the structures on Metecatl and those on Tetzcotzinco, which lead to look for other mechanisms that could be used to control the water flow, as will be explained further (Structure 5; Figure 5).

Another important factor in the analyses of the ancient water management systems may be critical flow. It is a concept in hydrological studies that defines how the speed and acceleration of water and the form of a canal can influence the state of water flow and good preservation of the structure (Farrington, 1980, p. 293). Critical flow is defined by the formula[10]:

F = V g × D .

The values obtained in this way determine the state of the water flow. The optimal condition is achieved when the critical flow reaches the value of 1. The watercourse is then stable and harmless to the canal. Values less than 1 signify tranquil flow, meaning obstacles on the route or even a slight slope may cause the water to stagnate. Values above 1 indicate rapid flow when larger obstacles or bends can cause the spill of water, and the flow itself can damage the canal (Farrington, 1980, p. 294). The problematic issue with the critical flow is the fact that it is most effective for analyzing canals and watercourses with a relatively uniform shape and slope. Hence, the proposed calculations are only hypothetical and averaged.

Despite the relative inaccuracies, the obtained data (Table 1) may provide some important information. In particular, the calculations show the tranquil flow in Aqueduct 1 and the main canal of Tetzcotzinco. Such a state of water could indicate the need for frequent inspection of these canals and their constant purification due to high sedimentation in low slope structures. Otherwise, the water could stop flowing or even flood the earlier sections of the system.

The opposite situation can be seen on the hill of Metecatl, where the calculations provide us with interesting information about the possible existence of water control mechanisms. At this point, the results of calculations suggest an extremely high flow velocity of up to 3.84 m/s and supercritical flow with a value of 2. The speed and flow were certainly too high for the use of such a water management system, which made it necessary to slow down the water and control it. Then, the features within the Structure 5 became relevant (Figure 5). In this place, there are, at least, three uneven floor levels (sort of terraces), which allowed to reduce the slope of the canals, and three shallow reservoirs (one rectangular and two circular) enabling the drainage of excess water.

Therefore, the accuracy for measuring structures or buildings with water control features also became relevant. To do this, profile contour projections based on 3D models were prepared which allowed the visualization of the contours of individual building features in the form of metric lines. Such imaging, enabled to make measurement analyses on various sectors of the architectural structure. The sections made in this way also permitted calculations of the volume of water reservoirs which revealed the maximum amount of water stored and distributed in Tetzcotzinco (Table 2).

Table 2

Results of the volume measurements of water reservoirs

Object Diameter (m) Depth (m) Volume (m3) Capacity (L)
Reservoir 4 4.2 0.91 12.601 12,601
Reservoir 2 1.38 0.68 1.016 1,016
Reservoir 1 3.98 1.31 16.289 16,289
Reservoir 3 1.2 0.57 0.644 644
Structure 5 – reservoir 1 2.53 0.52 2.6125 2612.5
Structure 5 – reservoir 2 2.63 0.38 2.063 2,063
Structure 5 – reservoir 3 (rectangular) Dimensions 0.26 0.2625 262.5
0.99 × 1.02

As a result of these calculations, it was estimated that the total capacity of Tetzcotzinco’s reservoirs was 35,488 L at one time. This amount may suggest that these structures did not function as permanent storage of potable water for the larger community. At the same time, it should be remembered that the system in Tetzcotzinco was open and had a constant water flow, which would mean that the reservoirs were constantly filled with water, and their actual long-term efficiency would be much higher. Although the form of the reservoirs (resembling small pools with stairs and benches) also does not support the hypothesis that they serve as water storage structures, they could be used as an emergency water source in special cases, e.g., during a drought (when the water stopped flowing through the canals). However, the exact function of these structures, especially for the consumption of the local population or agriculture, requires further analysis. At the same time, it should be remembered that these reservoirs could also have aesthetic and ritual functions, especially as water mirrors and ceremonial places. Then, the volume capacity of such pools would not matter as much as their form and location.

In addition, cross-section projections of the 3D models were analyzed. Thanks to the high accuracy of the scans, inaccessible places and structural features during the fieldwork, such as small water outlets placed at the bottom of water reservoirs (Figure 6), can be virtually reached. This enables tracking the exact directions of the water drainage.

Figure 6 
                  Cross-section projection of reservoir 4 with a visible outlet below the bottom of the reservoir.
Figure 6

Cross-section projection of reservoir 4 with a visible outlet below the bottom of the reservoir.

Irregularities and changes in the structure of architectural objects, particularly inclinations and collapses resulting from erosion and tectonic activity, were also observed with the aid of digital tools (Figure 7). These observations allowed noting the places most exposed to natural damage, which may be a key element in the maintenance and reconstruction of the hydraulic complex.

Figure 7 
                  Example of wall collapses in the Reservoir 4 complex: (a) view of the inclination and (b) area that is exposed to damage.
Figure 7

Example of wall collapses in the Reservoir 4 complex: (a) view of the inclination and (b) area that is exposed to damage.

Moreover, the 3D documentation of Tetzcotzinco also allowed to prepare new and precise metric plans for individual buildings, including those used in water distribution (Figure 8a). Based on two-dimensional projections, new architectural plans for the whole of Tetzcotzinco’s architecture were made which contributes to the list of maps made by previous researchers (Figure 8b). This documentation could point to amends for previous measurements but also place to scrutiny the topic of water management on the basis of architectonical analyses.

Figure 8 
                  (a) Plan of the Reservoir 4 complex based on the 3D model and (b) Plan of the Reservoir 4 complex elaborated with traditional methods (García García, 2007, p. 156).
Figure 8

(a) Plan of the Reservoir 4 complex based on the 3D model and (b) Plan of the Reservoir 4 complex elaborated with traditional methods (García García, 2007, p. 156).

Based on the detailed analyses of 3D models of these structures and the plans of buildings, the exact water flow at the site was able to be traced (Figure 9). The directions of water flow were marked, not only with the differences in heights, especially in the canals, but also based on the construction of the reservoirs. Analyses of 3D models allowed finding water outlets in some reservoirs and tracing their directions. In this way, it was possible to connect the entire water management system and map a possible further course of the water, especially towards the southwestern slopes of Tetzcotzinco, with the direction of the outlet discovered in Reservoir 1. Although a precise analysis of this water flow still requires further studies and archaeological surveys, the observation of a water outlet in this structure seems to suggest a connection between the central water management system and the external canal, described in the next section.

Figure 9 
                  Water flow with outlet directions. Due to the level of destruction and erosion of Reservoir 3, it is currently impossible to determine the exact water flow and location of outlets within this feature.
Figure 9

Water flow with outlet directions. Due to the level of destruction and erosion of Reservoir 3, it is currently impossible to determine the exact water flow and location of outlets within this feature.

3.3 The External Canal

During the archaeological survey, there were indications for the discovery of a “new canal” at the lower slopes of Tetzcotzinco (Figures 4 and 10), which had not been mentioned in the literature before. The surveyed area is located approximately 100 m below the main path of the site, meant for pedestrian who visit the site. The area is currently overgrown with dense vegetation, and in many sections, it is very steep, making it difficult to access the area and using some of the documentation techniques. Therefore, the survey here focused on searching for archaeological remains, documenting them with digital photos, and measuring them using handheld GPS.

Figure 10 
                  Construction of the external canal: (a) pre-Hispanic part and (b) cement-like pipe.
Figure 10

Construction of the external canal: (a) pre-Hispanic part and (b) cement-like pipe.

The canal spreads between 2,439 and 2,479 m a.s.l. and probably runs along the entire length of the hill of Tetzcotzinco and extends to the east (Figure 4). The archaeological record indicates the remains of this watercourse at a length of 1,430 m. The best-preserved parts of this canal are located in the northwestern part of the site. Contrary to the previously described features from the central part of the site, this canal is not accompanied by a distinct path. So far, it has not been able to locate the end of this canal due to its course through private properties that partially cover the northeastern parts of the archaeological site.

On the southern side, the canal is certainly worse preserved and more damaged. Nevertheless, it is still possible to capture most of its course. It surrounds the hill below the central part (both the central path and Structure 4 below), and it accompanies the formerly cultivated terraces along their entire length. In the eastern section, the canal probably passed towards the hill of Metecatl and was connected with one of the outlets coming from Structure 8 and Structure 9. The exact route of this connection was not observed due to the impossibility of conducting survey caused by the altitude and vegetation. Preliminary analyses and observations suggest, however, that the discovered canal has its origins in Metecatl.

The documented watercourse seems to coincide with the canal mentioned by Parsons (1971, p. 145) and described by him as a functioning structure. Despite the proximity of both watercourses and the similarity of their route, there is evidence that can confirm that they are two different canals. The newly documented object is not currently in use and its condition does not indicate that it could function over the last century. Moreover, the southern part of the canal does not follow the route marked by Parsons. This researcher documented a functioning watercourse, which at the height of Structure 7 changes its direction by 90 degrees and heads south towards the modern settlement of San Dieguito. The new canal does not change its route in the southern part and continues to the east, along the hill of Tetzcotzinco to the hill of Metecatl. It has been observed that the new canal contains various construction techniques. In particular, the southern part was made entirely of masonry (Figure 10a), with the bottom of the canals made of flat stone slabs surrounded by low walls. In some sections, this channel is located on the edge of the terrace, forming its outer border. In the northern part, there are differences in canal construction technology. The main part was also made with masonry; however, it was changed slightly. The canal walls are made of large, flat stones and slabs plunged vertically into the ground instead of the standard walls of small stones joined with mortar. There was also a construction technique within the external canal but used on a smaller scale, where it was carved in natural rock; both types alternate here, which proves the dependence of the use of different techniques on natural conditions.

In the northern part of the canal, there are visible “repairs” or “replenishments” (Figure 10b), which have not been noticed in the other constructions at the site so far. In several places, there are material modifications to form straight pipes or gutters. The analysis of this material shows a great resemblance to cement. The material used for the construction of the pipe was not discovered elsewhere on the site and does not appear to be of pre-Hispanic origin, which may suggest that it is one of the materials used in colonial architecture. The existence of cement-like fragments that probably served to complement the destruction in this channel would confirm the use of Tetzcotzinco in colonial times. Historical sources mention the destruction carried out by the Inquisition on this site and the official prohibitions related to Tetzcotzinco as a “ceremonial place” (Obregón, 2009, p. 24). However, confirmation of the canal repairs carried out during colonial times would suggest that Tetzcotzinco did not lose its importance completely after the conquest. Its practical and technological functions could still be important, including the supply of fresh water, both to arable fields and terraces, as well as drinking water. This canal hidden in plants, whose location and course seem to suggest its connection with human settlements located to the north of Tetzcotzinco, could therefore be the primary water source for humans in colonial times. The entire hydraulic system, destroyed in the central part as a symbol of the “old religion,” could still be used for a long time for practical purposes and was scrupulously repaired by the local community. It is also possible that despite the destruction of most of the site, its water management system was maintained with the consent of the Spanish authorities, which allowed the reusing of the old canals to supply water to local settlements. This discovery seems to change the view of Tetzcotzinco’s complex, previously understood primarily as a religious center, and it will draw attention to its technological and supply role. Tetzcotzinco itself could be understood then as the central hydraulic node and water storage center in the region.

3.4 Water Management System in the Surroundings of Tetzcotzinco

In this study, hypothetical courses of canals and aqueducts in the southern part of Acolhuacan were traced. The search for possible unidentified water sources for the system in Tetzcotzinco is still one of the most problematic issues related to the pre-Hispanic water distribution in the region. This stage of the research focused on the studies of maps previously explained (Figure 2). On the basis of the three proposed routes that delivered water from Tlalocatepetl, the elevation profiles of the terrain were generated. To do this, the Terrain Profile plugin in QGIS software was used, which produces a profile of a given route based on a bit-map with elevation data downloaded through the SRTM Downloader plugin in QGIS. The generated profiles show a graph that is embedded on the x-axis – representing the course of the road in meters, and on the y-axis – representing altitude data above sea level (Figure 11). This process was done separately for all three routes to verify whether the inclination of the land was steep enough on these trajectories, and therefore allow the water to run significantly downward; otherwise, the profiles would show significant doubts for the correct functioning and flow of each of the routes.

Figure 11 
                  Terrain profiles of elaborated routes.
Figure 11

Terrain profiles of elaborated routes.

This constituted the first stage of analysis, before moving on to a preliminary hydrological study, including the calculation of the hypothetical water velocity and the state of critical flow, which represents an initial step for the validation of the formulated hypotheses and will allow further viability of such canals’ routes for future multidisciplinary studies. These analyses were conducted for two different types of watercourses: artificial canals (Figure 12) and natural streams and waterways (Figure 13).

Figure 12 
                  Critical flow for canals’ routes.
Figure 12

Critical flow for canals’ routes.

Figure 13 
                  Critical flow for natural waterways’ routes.
Figure 13

Critical flow for natural waterways’ routes.

The first model was based on the assumption that each of the proposed routes runs entirely (from the source to Tetzcotzinco) over artificially constructed canals and aqueducts. Despite the lack of archaeological information on the form and dimensions of the canals on various sections of the route, it was assumed that this system could be similar in construction to the canal of Caño Quebrado and Aqueduct 1 in Tetzcotzinco. This assumption implies that the water would run along open channels with a relatively rectangular cross-section, 0.25–0.3 m wide and 0.2–0.25 m high. The hydraulic slope adopted in the calculations corresponded to the region’s natural topography. In this way, it was possible to estimate the speed and critical flow of different sections of each route. This, in turn, made it possible to identify – and therefore propose the lack of it – where such a canal construction would not ensure optimal water flow or the water velocity could destroy the canal.

The second type of watercourse that was analyzed was based on the assumption that the main part of the system would run through natural streams on local mountain slopes. Due to the lack of detailed data on the dimensions and form of individual streams in the region and insufficient knowledge of the hydrogeology of the region, uniform values were adopted for each of the proposed routes. As in the case of the first model, the obtained data allowed to identify and potentially eliminate the most problematic sections of each route. The analysis took into account both environmental problems (especially natural obstacles and terrain elevations) that would prevent effective water transport, as well as hydrological indicators that would suggest too high flow velocity.

The calculations and a comparative analysis of the results obtained for both models allowed combining them and achieving the most effective systems of flow (Figure 14). Therefore, the proposed routes take into account the share of both natural streams (on most parts of the routes, especially in the case of southern mountainous areas) and artificial canals and aqueducts (mainly in the inhabited areas near Tetzcotzinco). The analyses and calculations determined not only the most probable course of the studied routes but also their construction. Research on this issue is the first step in understanding the exact importance of Tetzcotzinco as a water distribution center for the entire region. Tracing potential long-range watercourses will help confirm or rule out the hypothesis about the existence of a regional canal network and understand how and by which routes water reached to Tetzcotzinco.

Figure 14 
                  Critical flow for canals’ and natural waterways’ routes.
Figure 14

Critical flow for canals’ and natural waterways’ routes.

The modeling allowed recreating the sections where the water velocity and its critical flow were too high for water to run in a canal typical for the region (similar to Aqueduct 1 or Caño Quebrado). In these sections, it was assumed that the water ran along the natural riverbeds. In the future, this type of research would permit calculations for the time needed to supply Tetzcotzinco as well as volumes of water supplied.

4 Discussion and Final Remarks

The present water management analyses provide a better understanding of how the canals, aqueducts, and reservoirs provided water from Tlalocatepetl to Tetzcotzinco. However, the results raise further questions about the technological possibilities at Acolhuacan and how the people of the time controlled water.

Non-invasive surveys, especially modern documentation created using three-dimensional scanning, enabled better recognition of the water management features at the Tetzcotzinco site and technological and hydrological analyses over the local system of canals and reservoirs. Based on 3D models and corrected measurements, it was possible to observe hitherto unrecognized water outflows and thus determine the precise directions of water flow. Furthermore, hydrological calculations showed the approximate flow velocity in different segments of the entire system, indicating significant changes in the way water is distributed in the central part of the site, which may suggest the existence of a hydraulic “node” in the final section of Aqueduct 1. Another water control mechanism was recognized in Structure 5 on Metecatl hill, which used multi-level uneven floors. Archaeometric measurements have also raised the question of the purpose of monumental reservoirs, the volumes of which may contradict their agricultural and economic use, thus reinforcing the thesis of the ritual functions of at least some water management features. Another essential point of the study was the documentation of an external canal on the lower slopes of Tetzcotzinco, correcting the plans proposed by Parsons in the 1970s. Determining the exact course of this feature suggested a connection between the central water management system at Tetzcotzinco, with local terraces and possibly also settlements, which – along with the remains of colonial or contemporary restorations of the canal– may confirm centuries-old economic use of these canals and prove the existence of an extended, long-range water management system in the regions surrounding Tetzcotzinco.

In regards to the flow of water on the regional routes, it should be mentioned that water could not have run uphill, and thus a pump, siphon, or waterwheel system must have been used on those fragments of routes where the terrain rose significantly. Another option would have been to build aqueducts on embankments in those fragments where the differences in terrain elevation were significant. This would allow the course of the canal to be gradually ascending so that the water pressure in the canal would be sufficient to overcome the slight elevation of the land. This is a fair likely possibility, as aqueduct construction was used in Central Mexico, as evidenced by the remains of such a structure at Caño Quebrado and Chapultepec (the latter, a well-known water provider for Tenochtitlan of the Mexicas)[11] (Doolittle, 1990, pp. 120–123),

Another aspect that raises new questions is the constructional capacity of the canals, as measured by the critical flow parameter. The present analyses concluded that if canals were to be constructed along the entire length of the designed routes, then there would be many fragments of those routes where the critical flow of water would be too great and could cause damage to the canals or spillover of that water from open canals. However, this does not mean that the water could not continue to run as long as the channel was not too damaged. These results, however, give rise to the hypothesis that it seems most likely that in those places where the water ran by natural watercourses, no canals were built there, and these natural watercourses were prevalent along the entire route from Tlalocatepetl to Tetzcotzinco. The canal system would, therefore, only be used on those parts of the roads where natural watercourses were not present.

An important element of the analyses of the proposed regional waterways is the evaluation of their credibility in three contexts: the topography of the terrain, the hydrological network, and historical data confirming, or not, the possibility of a water channel going along a given route. The two routes, one proposed by Arribalzaga and the other described in Titulos, start on the slopes of Tlalocatepetl, a mountain of 4,120 m above sea level, while the route proposed by Parsons starts near Cerro Tepechichilco, a hill of 2,777 m a.s.l, located northwest of Tlalocatepetl. All routes pass through Metecatl (Parsons’ route on the south side, the other routes on the north side) and end on the eastern slope of Tetzcotzinco, at Structure 1.

Under the criteria of topography, in particular the elevation differences shown in terrain profiles (Figure 11), the route proposed by Parsons is the most suitable route for the water to run. Over the entire 7.9 km route, there is only one section of land that rises by 10 m over a length of 110 m. The route that was developed using data from Titulos is 19.5 km in total, and along that length, there are four sections where the water would have to overcome elevations: 20 m uphill over 3.3 km, 40 m uphill over 200 m, 30 m uphill over 743 m, and 10 m uphill over 216 m. The most problematic of the three is the route proposed by Arribalzaga, whose course actually is known most precisely. There are four significant elevations along the entire 20 km of the route: 80 m uphill over 923 m, 20 m uphill over 165 m, 20 m uphill over 349 m, and 90 m uphill over 730 m.

Regarding the criteria of the hydrological network, all three routes are located within contemporary watercourses, which allows to conclude that these watercourses are unlikely to have significantly changed their course throughout this time and indicates that these routes are more likely to be correct. The route that most closely follows the course of the modern hydrological network is the route proposed by Arribalzaga. This also obliges to suggest that natural water run-offs coincide with pedestrian paths.

Regarding the correspondence of the routes with historical data, naturally, the route based on Titulos, a colonial source, is the most consistent. The route proposed connects all the southern locations mentioned in this document. Although the exact course of the canal is hypothetical and has been correlated with topographical and hydrological data, this course still connects the key towns and hills mentioned in the historical sources. In addition, the studies of other local sources, such as Memorial de Los Indios de Tepetlaoztoc (Valle, 1992) or Mapa de Patlachiuhqui y Moyotepec (Rojas Rabiela, 2019, p. 17), confirm the existence of an extensive network of canals and aqueducts in this part of Acolhuacan and indicate that the course of these canals ran between particular settlements or hills. Thus, the route based on Titulos seems to be the most historically reliable system. At the same time, the historical criterion is the least consistent with the route proposed by Parsons, whose plans do not fully correspond to the places mentioned in sources (e.g., Titulos; Pomar, 1971[1891]).

In short, after analyzing the course of the three proposed routes considering topography, natural hydrological network, and the historical data, a clear answer to the question of which of these routes was the correct one and most probably used in pre-Hispanic times was not reached. It should be mentioned that there are different types of data for each of these routes since each was identified differently. However, each of the routes appears to be feasible, and perhaps they even have been in use simultaneously. Hence, an in-depth understanding of this issue and thorough validation of each of these models require further studies. Certainly, the first step to better develop long-range watercourse maps will be conducting interdisciplinary research in collaboration with the environmental and natural sciences. This could allow the correlation of proposed models with hitherto unaccounted factors that may have influenced the functioning and viability of these pre-Hispanic canals. Nonetheless, the proposed maps provide a basis for additional computational modeling as well as for future research involving archaeological prospection and potential excavation in order to complement and verify these hypothetical regional water courses.


This research was made possible by funding from the National Science Center of Poland (PRELUDIUM 12 Grant no. 2016/23/N/HS3/00819) and with the help of the National Institute of Anthropology and History of Mexico (Permit no. 2018–614). Special thanks to Stanisław Rzeźnik and Marcin Kulesza for their contribution during the fieldwork and posterior elaboration of the data. We also thank Katarzyna Mikulska for her help with the organization of the fieldwork and merit-related support. We thank hydrologist Pascal Weidema for his helpful answers to our (hydro-)questions.

  1. Funding information: This research has received funding from the National Science Center of Poland under the PRELUDIUM 12 grant, award no. 2016/23/N/HS3/00819.

  2. Author contributions: All authors have accepted responsibility for the entire content of this manuscript and approved its submission.

  3. Conflict of interest: Authors state no conflict of interest.

  4. Data availability statement: The authors confirm that the data resulting from this research are available within the article. Raw data that support the results of this study are available from the corresponding author, upon reasonable request.


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Received: 2022-10-22
Revised: 2023-07-10
Accepted: 2023-07-19
Published Online: 2023-08-10

© 2023 the author(s), published by De Gruyter

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