Management Techniques of Ancestral Hydraulic Systems, Nasca, Peru; Marrakech, Morocco; and Tabriz, Iran in Different Civilizations with Arid Climates

Abstract

The research aims to evaluate various management techniques of Ancient Hydraulic Systems (AHS) in different civilizations in arid climates, in cities located in Nasca in Perú (Puquio), Marrakech in Marruecos (Khettara) andTabriz in Irán (Qanat). The scarcity of water resources in these areas compelled the inhabitants to seek water management solutions to meet the necessary water supply for the population at the time. The methodology employed was a case study in which climatic data, supply, and operation of AHS were analyzed. The different indicators studied resulted in findings that, in the case of Nasca, the system relied on lintels, utilizing robust materials such as stone. They employed geometry to control water flow velocity, inclined walls to prevent collapses, and terraces to facilitate access to underground galleries. In the cases of Tabriz and Marrakech, their systems were based on excavations and reinforcements primarily using clay and earth as materials. In conclusion, the techniques employed in different civilizations are responses to contextual realities, offering an adaptive solution to environmental and physical challenges with a sustainable focus within their immediate surroundings.

1. Introduction

Since ancient times, water resources have been crucial for both domestic use and agriculture. Approximately 20% of the world’s water supply is used for irrigating cultivable land, which generates about 40% of the global food supply and 60% of cereals [1]. Moreover, 80% of the water is on the surface, while the rest is underground or in the form of vapor in the atmosphere [2]. These facts are intrinsically related to global challenges outlined in the 6th Sustainable Development Goal (SDG), which promotes sustainable water and sanitation management, which takes special significance in arid or semi-arid regions [2]. Due to its limited availability, water requires careful management to meet human needs, protect ecosystems, and mitigate climate change [3,4].

T5% of the world’s population lives in the driest half of the planet, which means that millions of people do not have access to this resource [1]. Therefore, ancient techniques were developed for water collection, such as Khettaras or Qanats [5]. In the Middle East, they are called Falaj or Qanat; in the Mediterranean, they are known as Foggara or Khettara; in Central Asia, Karez; in Peru, there is the Puquio; and in Japan, Manbo [6]. Furthermore, throughout the history of different cultures, they have been called various names such as quanat, Canant, moonlight, kanat, khanate, khad, kanaye, or ghannat in Iran; kahrez, kariz, kah-riz, karaz, or kakoriz in Southeast Asia; mayon, iffeli, mgoula, khottara, or rhettara in North Africa; and falaj, aflaj, or felled in Arabia [7,8].

It is generally assumed that they originated under Persian influence (Iran and/or the Arabian Peninsula) since these regions have a significant number of Qanats today. They then spread westward and southward into Europe during the reign of Alexander III of Macedon and the New World [9]. As for the Nasca Puquios, authors view them as a byproduct of the Nasca culture [9,10,11,12].

The application of these ancestral water collection and distribution techniques in agriculture has proven beneficial in arid and semiarid regions where water resources are limited [13,14,15,16]. These techniques first involve identifying available underground water sources and then constructing and maintaining channels and vertical wells that connect a point on the surface with groundwater, creating a slope [12,16,17]. The extracted water is distributed to the fields through channels and gravity-based irrigation systems [13,17]. These traditional techniques, adapted to local conditions, enable efficient and sustainable water utilization in agriculture [16,17].

Throughout history, human communities have faced difficulties in accessing water due to geographic, climatic, and demographic factors; likewise, AHS has encountered an increasing number of issues [18,19,20]. These challenges include rapid population growth, irregular rainfall, droughts, depletion of groundwater and aquifers, lack of maintenance, new technologies, the disorderly growth and urban expansion in rural areas, disappearance of construction techniques, disconnect between governance-population, and water pollution [1,3,5,13,21,22].

The growth of the global population is occurring at a significant pace, with an annual increase of approximately 80 million individuals. This situation entails a requirement of about 64 billion cubic meters of freshwater each year [1]. This scenario indicates that the demand for water will continue to escalate in the coming years, exerting increasing pressure on the available land resources [1,23,24].

Similarly, water scarcity is common in arid regions due to the irregularity of rainfall, which varies in time and intensity [21]. Since heavy rainfall events are characteristic of drylands and desert margins, a large portion of the water is lost through surface runoff and does not get stored in AHS [21]. On the other hand, droughts are a problem for communities as they can last for extended periods and cause water shortages, as the water is quickly absorbed by the soil or evaporates before it can be utilized [5,18,19,21]. This has a negative impact on agricultural production, which in turn can lead to food insecurity and economic problems, especially in communities whose main source of income is agriculture.

The extraction of groundwater often exceeds natural recharge, resulting in persistent depletion of groundwater and aquifers, which subsequently impacts environmental flows in rivers and places associated ecosystems in a vulnerable situation [5,25,26]. This excessive extraction, coupled with intensified water exploitation, reduces the use of AHS as they do not have sufficient supplies to maintain their flow [5,22].

Similarly, in these arid regions, there is a tendency for disconnection between their governments and the population regarding collaborative and controlled management, as there have been cases of Khettaras drying up due to the absence of proper management [13]. Additionally, they face indifference from the population towards their maintenance and preservation, partly due to the high economic cost of drilling for access to deeper groundwater but also due to the lack of knowledge among the population about their existence and importance for sustainable development and cultural heritage [3,5]. An example of this lack of care from the population and their governments, as well as their disinterest, can be seen in Figure 1.

With technological advancements, new modern hydraulic systems such as deep wells and underground water pumps have been developed, among others. These systems deplete water resources, impact the surrounding ecosystems, and tend to degrade the soil [25,27]. Furthermore, the disorderly growth and urban expansion in rural areas irrigated and supplied by these systems, such as the pumping system, have caused deterioration and destruction of some of AHS, severing their ties with traditional social structures and the community, leading to abandonment by the population [13]. Likewise, construction techniques that were once used (AHS) have vanished due to the decline of specialized social groups in construction, as subsequent generations have lost this knowledge, thus limiting the capacity to develop new AHS [3].

In addition to these issues, a significant problem arises related to pollution, which intensifies due to constant interactions between groundwater and surface waters, creating a profound effect on their chemical composition, which in turn can result in a decrease in the availability of clean and safe water for use [26,28]. In other words, this interaction has practical consequences on the quantity and quality of water in any of the systems [25,26].

Great hydraulic engineering works were carried out that were significant in their time and continue to have a great impact on engineering, such as in Peru (city of Nasca), Morocco (city of Mechouar-Kasbah), and Iran (city of Tabriz) [4].

Therefore, the present investigation aims to evaluate the various management approaches of Ancient Hydraulic Systems (Puquio, Khettara, Qanat) in different existing civilizations of arid climates.

2. Materials and Method

In this section, a detailed description of the study areas is provided, followed by a comprehensive explanation of the methodology employed in the present study.

2.1. Places of Study

Three cities belonging to arid climates were analyzed: Nasca City in Ica, Peru (Figure 2A), which is located near the equator in South America; while Mechouar-Kasbah City in Marrakech-Safi, Morocco (Figure 2B) is situated in the northern region near the Greenwich line in Africa, and finally Tabriz City in Tabriz County, Iran (Figure 2C), which is located to the east of the Greenwich line in the Middle East [29,30,31].

2.1.1. Cantalloc Aqueduct, Puquio Hydraulic System—Nasca City

The Puquio is a hydraulic system that means “fuente” or “manantial” [9,32]. However, in the context of the Nasca culture, it is known as “huncólpi,” which consists of a network of channels, both surface and underground, that allow the extraction of subterranean waters [9]. In Ica, Nasca, the Cantalloc aqueduct is supplied by the lower Tierras Blanca’s River, and this river serves 135 users and 908.18 hectares through irrigation [33]. These were constructed by the indigenous populations before the arrival of the Spanish and represented a valuable legacy of hydraulic engineering [12]. In Ica, alongside traditional underground aqueducts, modern drip and sprinkler irrigation systems have also been introduced in certain commercial crops [34]. The archaeological studies show that puquios were absent during the Early Nasca period (Early Intermediate Period) and were used during the Inca conquest in the 16th century [11]. Furthermore, radiocarbon analyses by accelerator mass spectrometry reveal that puquio structures have existed since cal AD 560–650 and cal AD 600–660 [35].

2.1.2. Khettara Hydraulic System—Mechouar-Kasbah City

The Khettara is a hydraulic system that, through the use of gravity, transports water from the water table to the surface, allowing for the irrigation of fields in oases [3,36]. These structures are characterized by their resilience, adaptability, and sustainability, as they leverage ancestral knowledge to address environmental challenges and ensure a sustainable water supply for agriculture; with management rules in place, they ensure maintenance and a fair distribution of water among farmers, thus avoiding overexploitation of water resources and maximizing benefits for communities [37]. In Morocco, sprinkler irrigation projects and drip irrigation systems have been developed to optimize water use in agriculture, sometimes used in conjunction with khettaras [38].

In Morocco, khettaras are known for their significance in water capture and distribution within a context where 80% to 95% of water resources are allocated to agriculture, with around 40% sourced from groundwater [5]. These structures are recognized to have Persian influence, as seen in Iran and the Arabian Peninsula. It is considered that they were invented between 600 and 700 BC [13].

2.1.3. Qanat Hydraulic System—Tabriz City

Qanats are an ancient solution for water supply in arid and semi-arid regions, playing a vital role in the history of irrigation and human settlement [39,40]. In different regions, Qanats are constructed in a traditional manner and are essential for irrigation and domestic water supply in numerous settlements [17]. Their use has a significant impact on the socioeconomic organization and patterns of land ownership and tenure [14]. Furthermore, Qanats are not just a technique for accessing and managing groundwater; they have also influenced the landscape and prosperity of Iran, making their importance go beyond the technical aspects and being key to understanding the culture and civilization in the Iranian plateau [14]. Moreover, dams and drip irrigation systems have been constructed in Iran to store and enhance water use efficiency, respectively [41,42].

The use of qanats in Tabriz, such as No-Ras, dates back to the 13th century AD, having been a part of various hydraulic activities during the Mongol rule in the region [39,43]. In 1996, the No-Ras Qanat, particularly its final stretch encompassing the Fath Abad garden, point of outlet, and the historic Garden Mansion, was recognized as a historical heritage [39]. The majority of the qanat’s route traverses the village of Chavan, which houses an average of 2000 inhabitants partially interconnected through the use of No-Ras, extending to the suburbs of Tabriz [39].

2.2. Locations of Ancestral Hydraulic Systems

2.2.1. Case of Nasca City: Cantalloc Aqueduct Puquio

Figure 3C shows the route of the Cantalloc Aqueduct (Puquio), which has a length of 371.8 m. It originates from the Tierra Blanca River at point (1), located at an elevation of 640 m.a.s.l., with geographic coordinates 14°49′33.36″ south latitude and 74°54′38.23″ west longitude [29]. The aqueduct extends to a midpoint where it branches into two sections: One is the endpoint (2), which is located at an elevation of 638 m.a.s.l., with coordinates 14°49′35.87″ south latitude and 74°54′41.23″ west longitude; and the other end reaches a point (3) situated at 647 m.a.s.l., with coordinates 14°49′36.94″ south latitude and 74°54′31.38″ west longitude [29].

2.2.2. Case of Mechouar-Kasbah City: Khettara

Figure 4C shows the route of the Khettara in the city of Mechouar-Kasbah, which has a length of 660 m. It has different points, one being point (1) located at an altitude of 476 m.a.s.l., with geographic coordinates of 31°36′16.13″ north latitude and 7°59′44.48″ west longitude, and it extends to point (2) which is located at an altitude of 479 m.a.s.l., with coordinates of 31°36′5.47″ north latitude and 7°59′42.76″ west longitude [30]. Another point (3) is situated at an altitude of 477 m.a.s.l., with coordinates of 31°36′13.81″ north latitude and 7°59′42.11″ west longitude, and it extends to point (4), which is located at an altitude of 479 m.a.s.l., with coordinates of 31°36′4.94″ north latitude and 7°59′38.02″ west longitude [30].

2.2.3. Case of Tabriz City: No-Ras Qanat

The study site is located on the outskirts of the city of Tabriz, which is situated in the southern region of the Asian continent in the country of Iran. It serves as the capital of East Azerbaijan province and is part of Tabriz County [31,39]. The site forms part of a complex environmental and urban system that revolves around the city of Tabriz, the Zagros Mountains, and Lake Urmia [40].

Figure 5C shows the route of the No-Ras Qanat of Tabriz, which has an approximate length of 3.5 km [31]. It extends from the slopes of Sahand Mountain, with its starting point (1) at an altitude of 1780 m.a.s.l., with geographical coordinates of 37°58′52″ latitude north and 46°23′60″ longitude east, near the village of Chavan, to the drainage located in the Fath Abad garden, with its endpoint (2) at an altitude of 1683 m.a.s.l., and coordinates of 38°00′26″ latitude north and 46°23′19″ longitude east [31]. There is an interruption at the midpoint (3) due to the presence of a sand and gravel mine [39].

2.3. Methodology

The study was divided into three phases, as illustrated in Figure 6, and was conducted according to the sections detailed below.

2.3.1. Climate Analysis

Climatic analysis is a fundamental tool for the evaluation of groundwater resource quality in different regions [44]. This process involves a meticulous climatological study that encompasses essential aspects such as temperature, wind speed, humidity, and precipitation in the various intervention areas of arid climates. This study allows for an understanding of how these factors impact ancestral hydraulic systems [44,45]. The process is detailed as follows:

• Data compilation of meteorological information from the Weather Spark EPW for the year 2022, which includes temperature (°C), wind speed (km/h, hours per year), humidity (%), and monthly and annual precipitation (mm);
• Rigorous statistical processing of the collected data;
• Generation of graphs that present monthly data for parameters such as maximum and minimum temperature, maximum and minimum humidity, maximum and average annual precipitation, as well as monthly wind speed;
• Analysis of the results obtained from each region and their influence on the studied hydraulic systems.

2.3.2. Supply and Operation Analysis

The initial phase of hydrographic analysis begins with accurate geolocation of each study region, supported by detailed cartographic representations that provide a comprehensive view of the geographical arrangement of rivers in each area and their intrinsic relationship with the ancestral hydraulic system. Next, a thorough characterization of the river basins in each region is carried out, investigating key aspects such as their length and flow direction and delving into the geological peculiarities that define them. Furthermore, a meticulous analysis of the river discharge is conducted, contributing to a more comprehensive understanding of its impact on local water supply and, ultimately, on the operation and relevance of the ancestral hydraulic system in its respective geographical context.

2.3.3. Analysis and Interpretation of Results

The final phase of the research analyzes the three hydraulic systems based on the following criteria:

• Analysis of Distribution Area and Sizing: In this stage, a meticulous collection of information is conducted, including the location of each ancestral hydraulic system, a description and sizing of its underground components, a specific distribution of its elements, a detailed schematic section, and an evaluation of the topography of the study area.
• Soil Typology: This analysis is based on the collection of relevant data regarding the types of soil present in each intervention region, which includes a detailed description of soil characteristics such as texture, water retention, infiltration capacity, and erosion. Additionally, it assesses how these characteristics may influence the implementation and durability of ancestral hydraulic systems in each specific area.
• Construction System and Materials: This analysis is based on multidisciplinary data collection, documentary research, and geological and historical analysis of the construction systems and materials used in the three study areas. Furthermore, a thorough review of historical and scientific sources is carried out to provide a comprehensive understanding of the evolution and uniqueness of these ancestral hydraulic systems, considering geological peculiarities and specific needs of each region.

3. Climate Analysis

According to the Köppen classification, the study area in Nasca corresponds to a desert climate (BWh). Similarly, the study area in Marrakech corresponds to an arid, steppe, and hot climate (BSh), while the study area in Tabriz corresponds to an arid, steppe, and cold climate (BSk). All three study areas belong to the arid climate, yet they exhibit distinct climatic features that differentiate and uniquely influence the behavior of groundwater throughout various months of the year, including factors such as temperatures, winds, humidity, and precipitation in 2022. It is crucial to highlight that any climatic variations among these study areas are pivotal as they can impact the recharge, discharge, and quality of groundwater and its behavior across diverse contexts [46,47,48].

3.1. Temperature

It is noteworthy that these climatic variations exert a direct impact on the management and operation of subterranean hydraulic systems [44]. In Figure 7, Nasca reaches average maximum temperatures during the months of February and March, at 30 °C, and its average minimum temperatures range around 15 °C from June to August [49]. Additionally, the annual temperature fluctuation is 15 °C, categorized as a moderate amplitude [49].

In areas with higher temperatures, such as Marrakech, where average maximum temperatures of 37 °C are reached in July, and average minimum temperatures are around 7 °C in January, with a temperature fluctuation between 15 °C and 16 °C [49]. During the summer period, there is an increase in temperature that leads to higher evaporation rates and water demand, which impacts the availability of storage systems, resulting in more frequent and prolonged droughts [49,50]. These conditions contribute to the formation of soil crusting and hydrophobic soils [50]. Consequently, during precipitation events, there is an elevated surface runoff and a decrease in groundwater recharge [50].

In the case of Tabriz, it experiences average maximum temperatures of 32 °C in the months of July and August and average minimum temperatures in January, reaching as low as −5 °C [49]. Challenges arise in locations with sub-zero temperatures like Tabriz, particularly concerning water freezing in the systems during the cold months [50]. On the other hand, in winter, temperatures vary slightly, ranging between −3 °C and 5 °C at the beginning of the season and between −3 °C and 6 °C towards the end, with an average temperature fluctuation of 8 °C during this period. The annual temperature fluctuation is 37 °C, which is considered a high amplitude [49].

3.2. Wind Rose and Wind Speed

Figure 8A shows that in the Nasca study area, there are two notable wind directions: northeast and southeast, with the former being predominant [51]. Northeast to southeast winds are the most frequent and strong, with a total duration of 4192 h/year and speeds that can reach up to 38 km/h during a period of 103 h/year [51]. These winds contribute to the flow of water in the puquio by means of wind force [52]. Likewise, Figure 8A′ shows that the months with the highest wind speeds are March and from May to October, with speeds ranging from 12 km/h to a maximum of 38 km/h. However, the months of March, May, and October have speeds starting from 5 km/h, and July records a maximum speed of up to 50 km/h during a period of 0.1 days. In contrast, the months from November to February and April have the lowest speeds, ranging from 5 km/h to a maximum of 28 km/h, except for January and December, which reach a maximum of 19 km/h. It is important to note that February is characterized by having the longest duration of minimum speed, lasting for 2.7 days [51].

In Figure 8B, Marrakech also exhibits notable winds, such as north-northwest, northeast, and in the opposite direction, southeast and south-southeast, with the predominant direction being north-northwest [53]. North-northwest to south-southeast winds are the most frequent and strong, with a total duration of 1262 h/year and speeds that can reach up to 19 km/h, with a maximum duration of 61 h/year at their maximum speed [53]. In Figure 8B′, it can be observed that the wind speed in all months ranges from 5 km/h to a maximum of 28 km/h, except for December, where it reaches up to 19 km/h for 1.2 days [53]. It is important to note that December has the longest duration of low winds, with 11.3 days, while June has the shortest duration of low winds, with 0.3 days. On the other hand, April has the longest duration of strong winds, with 0.9 days, while the months from August to October have the lowest durations, with only 0.1 days [53].

In Tabriz (Figure 8C), there are two notable wind directions: northeast to southwest and in the opposite direction, south-southeast to north-northeast, with the predominant direction being northwest due to its duration [54]. Northeast to southwest winds are the most frequent, with a total duration of 1814 h/year and speeds that can reach up to 28 km/h, with a maximum duration of 2 h/year [54]. Additionally, Figure 8C′ shows that the months with the highest wind speeds range from February to April, with speeds ranging from 1 km/h to a maximum of 61 km/h, with February and March having the longest durations of maximum speeds, at 0.2 days [54]. On the other hand, the months of May and from October to January are characterized by relatively low wind speeds, with a maximum of 50 km/h and a minimum of 1 km/h, except for May, which starts at 5 km/h. It is worth noting that November has the longest duration of low winds, with a duration of 0.7 days. Similarly, June and September have slightly lower speeds, with a maximum of 38 km/h, while in June, the minimum speed is 5 km/h, and in September, it is 1 km/h. On the other hand, the months of July and August have the lowest speeds, ranging from 5 km/h to a maximum of 28 km/h. Among these months, July stands out as the longest duration of minimum speed, with a duration of 0.5 days [54].

3.3. Relative Humidity

Figure 9 shows that, in Nasca, the month with the highest relative humidity is February (79%). The month with the lowest relative humidity is October (56%). In summer, the average relative humidity is 70.6%, which in turn benefits soil moisture retention and aquifer recharge, thereby increasing water availability [50,55]. In contrast, in winter, it is 66.3%, which reduces the soil’s water retention capacity, which might necessitate additional measures to ensure sufficient water supply during those periods [50]. Additionally, Nasca has an average relative humidity of 65.5% [55].

In Marrakech, a lower relative humidity is observed compared to Nasca. In this locality, the month with the highest relative humidity is February (66%). Furthermore, the months with the lowest relative humidity are July and August (47%). In the summer months, the average relative humidity is 66.3%, whereas in winter, it rises to 70.6% [56]. These climatic conditions can lead to increased evaporation and impact the availability of water in the hydraulic systems [50]. Marrakech has an annual average relative humidity of 58.1% [56].

In Tabriz, the month with the highest relative humidity is January (74%), and the month with the lowest relative humidity is August (39%). On the other hand, the average relative humidity in summer is 40%, and during winter it is 71.3% [57]. These climatic patterns generate benefits for water retention and recharge during winter, but they also present challenges in summer due to low humidity levels, which result in higher water demand and can impact the efficiency of water capture and storage systems [50]. The annual average relative humidity in Tabriz is 52.9% [57].

3.4. Precipitation

Figure 10 shows that in Nasca, the month with the highest amount of precipitation is February, with an average of 8.6 mm [49], leading to increased aquifer recharge [58,59]. Conversely, the lowest amount of precipitation occurs in July and August, with an average of 0.5 mm [49]. This scarcity necessitates crucial water management and conservation, resulting in soil crust formation and hydrophobic soils [60]. During precipitation events, there is heightened surface runoff and reduced groundwater recharge [60]. The average precipitation is 40.7 mm per year [49].

In Marrakech, water management poses fewer challenges due to the consistent recharge of the hydraulic system. November has the highest precipitation, with an average of 36.0 mm, which could exceed soil infiltration capacity, causing increased surface runoff and consequently reducing groundwater infiltration and recharge [60,61]. In contrast, July has the lowest, with an average of 0.8 mm [49]. The average precipitation is 217.8 mm per year [49].

Finally, in Tabriz, April has the highest amount of precipitation, with an average of 22.9 mm, leading to increased aquifer recharge [58,59]. Conversely, the lowest amount is recorded in August, with an average of 2.8 mm [49]. The average precipitation is 127.7 mm per year [49].

4. Supply and Operation Systems

4.1. Case of Nasca City: Cantalloc Aqueduct-Puquio

Figure 11A provides the location map of rivers in Nasca City, where the study site of the Cantalloc Aqueducts is situated. These rivers exhibit different directions, lengths, and altitudes along their course. The journey begins on the high plateau at an altitude of 4000 m.a.s.l., where the water flows into the Tierra Blanca River, also known as the Tambo Quemado River [62]. This river follows an east-west direction and spans a length of 75 km, with a maximum width of 700 m. It has an average slope of 7%, and its basin covers an area of 508 square kilometers, with 230 square kilometers corresponding to the active basin. This river plays a significant role in supplying the study area, although its flow is irregular, ranging from 2.43 m³/s in May to 0 m³/s in September, with peak discharges occurring from January to April and a sharp decline in flow from April to May, leading to complete drying of the channels [33,62].

Subsequently, the water continues its course and meets the Aja River at an altitude of 400 m. The Aja River is formed by the convergence of three streams, the Hospicio River, Chillhua Stream, and Tototumi Stream, at an altitude of 4200 m [62]. The Aja River has a length of 1000 m and flows in an east-west direction. The altitude at the confluence point is 462 m, with a height difference of 317 m. The average slope is 5%, decreasing to 2% and even less before joining the Tierra Blanca River [62]. The Aja River basin covers an area of 513 square kilometers, with 295 square kilometers attributed to the active basin, while its flow varies from 3.65 m³/s in March to 0 m³/s in September [33,62]. Afterward, the water flows into the Nasca River, formed by the confluence of the Aja River and the Tierra Blanca River, at an altitude of approximately 460 m. The river has a length of 42 km and empties into the Pacific Ocean when it connects with the Grande River at an altitude of 155 m [62]. The Grande River has an approximate area of 4584.0 square kilometers, with an average elevation calculated at 50% of the area of 1736.62 m above sea level [33]. It is also intermittent in nature, flowing during the rainy months from December to April, while the rest of the year remains dry [33].

On the other way, Figure 11B provides a closer view of the water bodies in the city of Nasca, specifically the Cantalloc Aqueduct. It can be observed that the Tierra Blanca River directly connects to it. This basin is of great importance as its functioning contributes to the water supply of the region, both for agriculture and for domestic use by the population of Nasca City [52].

4.2. Case of Mechouar-Kasbah City: Khettara

Figure 12A presents the location map of rivers in the Marrakech region, where the study site of the Khettara is situated. It illustrates the various directions and branches of the rivers as they traverse the region. The journey begins in the High Atlas, a sub-range of the Moroccan Atlas, at an elevation of 4167 m above sea level. From the northern flank of the High Atlas, the rivers divide into five basins belonging to the Tensift River: Nfiss, Gheraya, Ourika, Zat, and Rdat, which connect to the main river from west to east [63]. In this sequence, the Rdat River spans 50 km, and its significant erosion has contributed to the sedimentation of the river [64]. The next notable river is the Issyl, whose basin originates from the High Atlas and stretches for 87 km, flowing in a south-north direction [65]. These two aforementioned rivers merge into the Tensift River, which flows from east to west and extends for 250 km, making it the most important river as it reaches the Atlantic Ocean [63]. The Tensift Basin receives a flow of 6224 Mm³ and generates an estimated runoff of 1117 Mm³; it flows through the basin via the Tensift River and its tributaries [66].

Furthermore, Figure 12B provides a closer view of the water bodies in the city of Mechouar-Kasbah. It shows that the Issyl River is the closest river to the Khettara system in the study area. Its significance lies in its role of supplying water to the region, and it is considered a river with easy collection of rainwater for domestic use by the population of Mechouar-Kasbah [65]. However, the Khettaras in the Tensift Basin sector are nearly all out of service, and the amount extracted from these tunnels is now negligible [66].

4.3. Case of Tabriz City: No-Ras Qanat

In Figure 13A, the location of the No-Ras Qanat study area is depicted, showing the rivers in Tabriz County. These rivers have varying lengths and flow directions. The journey begins at the Sahand Mountain, situated at an elevation of 3707 m.a.s.l., where the Mehran-Rood River originates. This river flows through the city of Tabriz in a southeast-to-northwest direction. Ultimately, it joins the Aji-Chay River on the western side of the city, which is considered the most significant river in the region. With a length of 265 km and an average elevation of 1481 m.a.s.l., the Aji-Chay River flows from east to west. The waters of the Aji-Chay River have relatively high salinity, and it discharges into Lake Urmia, located between East Azerbaijan and West Azerbaijan [39,67].

Figure 13B provides a closer view of the aquifers surrounding the No-Ras Qanat in the Tabriz study area. Two river branches intersect with the studied Qanat system; however, they are seasonal and only have water flow during specific periods. The Mehran-Rood River, which significantly contributes to water transportation from the highlands to Tabriz, is also identified. It plays a vital role in irrigation for agricultural areas and domestic use [67].

5. Results

5.1. Area Distribution and Sizing

5.1.1. Case of Nasca City: Cantalloc Aqueduct Puquio

In Figure 14A, the location of the Puquio near the southern bank of the Tierra Blanca River is depicted. Additionally, the figure provides valuable information about the direction of the underground flow, which moves from east to west, following the natural slope of the terrain [52]. The Puquio consists of two main zones: the underground zone and the open trench [52].

In Figure 14B (4–6), the parts of the underground zone, such as the chimneys, also known as “ayes”, and the underground galleries, are shown [68]. The funnel-shaped “ojos” facilitate the flow of water through the force of the wind and provide access for the maintenance of the underground galleries, where the water travels towards the surface [52]. As shown in Figure 14B (3), before entering the open trench zone, the water passes through the “socavón”, which serves as the transition point between the two zones, to reach the open trench, which is the surface part of the Puquio [52,69]. Afterward, as depicted in Figure 14B (2), the water follows a meandering path with curves and sometimes abrupt changes in direction to control its speed, eventually reaching the reservoir called “cocha” Figure 14B (1) located at the end of the system for subsequent use in irrigation or to flow directly through the irrigation canals [16,52,69].

Regarding the specific distribution, the starting point of the Puquio is the first branch in the northeast, near the river. This branch extends for 71 m and has three chimneys [52]. As it progresses, the first branch divides into two: one on the east side, with a length of 265 m and 13 chimneys, continuing below the bed of the Tierra Blanca River for an unknown distance, and another on the west side, with 104 m and six chimneys [52]. This latter branch reaches the “socavón”, where the underground gallery transitions into an open trench and culminates its flow in the cocha [52].

In Figure 14B, a schematic section A–A′ of the Puquio is presented, and a total of 15 vertical wells “ayes” are identified in the cross-section, with spacing ranging from 0.80 to 1.00 m, corresponding to the slope of the graph [70]. The conical “ayes” can have an opening as wide as 15 m in diameter at the surface of the ground, narrowing down to one or two meters at the bottom, with a depth of a few meters up to approximately 10 m [52]. Likewise, the underground water gallery has a width ranging from 50 cm to 80 cm and a height of 90 cm to 150 cm, allowing for the entry of maintenance personnel [52,70]. They have a length ranging from 300 to 1500 m and exhibit a rectangular or slightly trapezoidal section [68,70]. These galleries are excavated at depths ranging from 3.00 to 8.00 m below the surface of the ground.

It exhibits a flat, undulating, and strongly undulating topography, indicating a significant variation in altitude within the study area, ranging from 636 m.a.s.l. to 641 m.a.s.l. [29]. It covers a length of 208 m with a maximum slope of 10.5%, resulting in sectors prone to channel erosion, and the average gradient is 1.4%, which facilitates the continuous and controlled flow of water at the underground level [29,71].

5.1.2. Case of Mechouar-Kasbah City: Khettara

In Figure 15A, the location of the Khettara in the study area is depicted, indicating the direction of the underground flow according to the slope of the terrain (from south to north). It is also shown in relation to the surrounding environment, with the Raid Garden Hotel situated in the southern area Figure 14B (4), while the northern direction consists of vacant land Figure 15B (1). The Khettara exhibits minimal vegetation along its course and surroundings, primarily due to its state of abandonment and deterioration, as evident in Figure 15B (2,3), which depicts blocked wells filled with waste. In this sector, a total of 24 vertical wells are identified [30].

Figure 15B presents a schematic section A–A′ of the Khettara, where a total of 13 vertical wells are identified in the cut, spaced at intervals of 18 to 50 m, corresponding to the slope of the graph [3]. These wells have varying widths between 50 cm and 100 cm, with depths ranging from a few meters to approximately 10 m. Furthermore, the underground water channel has a width between 50 cm and 80 cm and a height ranging from 90 cm to 150 cm [3], allowing access for maintenance personnel.

The study area presents an undulating and rugged topography, with an altitude ranging from 477 m.a.s.l. to 480 m.a.s.l. [30]. It spans a distance of 280 m, with a maximum slope of 13.3%, leading to sectors of the channel that are susceptible to erosion due to increased flow velocity, and it has an average gradient of 1.1%, ensuring controlled water flow within the khettara [30,71].

5.1.3. Case of Tabriz City: No-Ras Qanat

Figure 16A, the location of the Qanat in the study area is depicted, indicating the direction of the underground flow according to the slope of the terrain (from south to north). It is also shown in relation to the surrounding environment, with agricultural areas to the south and the historical Fath-Abad Garden to the north Figure 16B (1) [39,40]. Some parts of its course and the surrounding areas exhibit moderate vegetation, supporting the agricultural practices of the Chavan community.

Figure 16B presents a schematic section A–A′ of the Qanat, where a total of 54 vertical shafts are identified in the cut, spaced at intervals of 18 to 50 m. However, only four of them are accessible and in operation, while the rest are either unidentified or blocked, as seen in Figure 16B (3), which shows the access to one of the blocked shafts due to a rock obstruction [39]. Moreover, the Qanat has a depth ranging from a few meters to approximately 49 m, as observed in the Mother Well. Additionally, the underground water level, also known as “dehliz,” extends with a slight slope until reaching the surface outlet. It has an average width of 1 m and a height of approximately 1.5 m, providing ventilation, preventing water stagnation, and facilitating maintenance access [14,39].

The study area presents a highly undulating topography surrounded by mountainous features, with altitudes ranging between 1670 m.a.s.l. and 1782 m.a.s.l., covering an extent of 3.50 km [31]. The maximum slope is 12.6%, and the average gradient is 2.7%, which significantly influences water flow and distribution [31,71].

5.2. Soil Typology

In

Table 1. The soil typology of the study locations: Nasca City, Nasca; Mechouar-Kasbah City, Marrakech; and Tabriz City, Tabriz.

	Nasca	Marrakech	Tabriz
Region	Semi-arid	Semi-arid	Semi-arid
Type	Sandy clay (Sc) [72,73]	Silt loam (Sl) [15,72]	Clay loam (Cl) [74]
Texture	Medium [75,76]	Medium [75,76]	Fine soil [74]
Water Retention	Medium-High [75]	Medium-High [75]	High [75]
Water Infiltration	Low	High	Low
Erosion	High	Medium-Low	High [74]

, the comparison of each intervention site, Nasca, Marrakech, and Tabriz, shows that although they share a semi-arid climate, the soils in Nasca, Marrakech, and Tabriz have different characteristics and behaviors.

The soil in Nasca is mainly sandy clay (Sc), giving it a medium texture and a medium to high water retention capacity [72,73]. However, its infiltration capacity is low and prone to erosion. On the other hand, the soil in Marrakech is loamy, sandy clay, providing it with a medium texture and a medium to high water retention capacity [15,72]. However, it has a high infiltration capacity and a medium to low erosion potential. In the case of Tabriz, the soil is loamy clay, classified as fine-textured alluvial soil [74], with a high water retention capacity. However, it has a low infiltration capacity, making it prone to erosion, similar to Nasca.

In summary, we can affirm that the soils in Nasca and Marrakech share similarities in terms of water retention capacity and texture, while the soil in Tabriz is characterized by a finer texture and slightly higher water retention capacity [75,76]. However, Marrakech has an important characteristic: a high water infiltration capacity, making it more resistant to erosion.

This attribute potentially enhances the overall stability and durability of these systems, as the higher resistance to erosion minimizes the potential adverse effects of sedimentation and material wear. It also contributes to a prolonged lifespan of the subterranean structures and a reduced need for frequent maintenance or repairs compared to areas with lower infiltration capacity, such as Nasca and Tabriz.

Each region has its own geological significance and may require different soil management and conservation practices. The soils in Nasca and Tabriz are suitable for agriculture, while the soils in Marrakech may require careful water management for agriculture and soil protection. In conclusion, understanding the properties and behavior of the soil is essential for sustainable development and proper management of natural resources in any region.

5.3. Construction System and Materials

Table 2. Comparison of construction systems and materials in different study locations.

Ancestral Hydraulic Systems	Construction System	Roof	Wall	Floor
Puquio	Lintel	Flat stones [68,70] Wood (Huarango tree) [68,70]	River Stone Slate soil Clay [16]	Clay
Khettara	Excavation [3] and/or masonry [58]	Clay	Clay	Clay -
		Stone	Stone
Qanat	Conventional excavation [40]	Soil	Soil	Soil Clay -
		Clay	Clay
		Pumice stone	Pumice stone

provides detailed information regarding the construction system and materials used in the three study locations. In Nasca, Pre-Incas employed a construction system based on stable geometric figures to protect the structures from erosion caused by groundwater. They used a lintel system to resist the pressure of the soil, coating them with river stones to ensure proper settlement and improve adherence [52].

These lintels are made from flat stones extracted from nearby quarries [52]. Additionally, wooden beams made from the trunk of the Huarango tree were used in certain roof sections. The Huarango tree, scientifically known as “Prosopis pallida” and commonly referred to as “Algarrobo” in the Northern and Central Coast of Peru and “Huarango” in the Department of Ica, is abundant in the dry region of Peru and exhibits high water resistance [52,68,70,77]. In terms of the walls, inclined planes were used, and terraces were constructed to facilitate vertical access. The walls had an appropriate incline and were coated with river pebbles to guarantee stability [52]. River cobblestones, dry-stacked stones, stone slabs, as well as filling with earth and clay were employed [52].

In the case of the upper part, the open trench was lined with river cobblestones, and the aqueduct was covered with stone slabs or beams made from Huarango trunks. The “ojos” or openings were constructed using stones and Huarango logs, covered with excavated material [52,62]. Finally, in the present day, the walls are reinforced with concrete, similar to the “socavón” [52].

For Khettaras and Qanats, prior to construction, an exploratory well is excavated to verify the presence of the water table in the subsurface [3,78]. The construction process starts with the excavation of the first two wells, which are connected through a lower channel. Subsequently, a third well is excavated, following the same connection with the channel, and this process is repeated until reaching the final well, where the water table is reached. This forms the underground horizontal tunnel called “dehliz”, which directs the water flow [3,14,78]. Additionally, the vertical wells serve not only for water access but also for determining the correct direction and suitable slope for the dehliz, as well as facilitating the removal of excavated materials [14].

During construction, natural elements of the terrain and subsurface are utilized, and in some cases, clay rings are used as support. In the Khettara system, it has been documented that, depending on the soil stability, stone masonry is employed as an additional structure to prevent collapse [78].

The Puquio was constructed using a complex process with stronger structural support based on a lintel system and careful management of inclinations. Additionally, in the construction of some Khettaras, stone masonry walls were used as additional support, providing greater stability and containment. On the other hand, in Tabriz, a system consisting of an excavation with clay linings for containment was employed, making use of natural elements of the terrain, such as stones, rocks, and earth.

6. Discussion

Ancestral hydraulic systems have played a vital role in water supply, both for human consumption and for the agriculture that characterizes these regions. These systems have been characterized by their ability to efficiently harness available water resources, capturing and storing groundwater and distributing it equitably within the community. The existence of structures such as the Khettara in the city of Mechouar-Kasbah, Morocco, the Qanat in the city of Tabriz, Iran, and the Puquio in the city of Nasca, Peru, showcases the ability of these societies to adapt to their environment and ensure a reliable water supply even in adverse climatic conditions. Additionally, in Roman civilizations, renowned for their aqueducts, these systems have proven to be an effective solution for meeting basic water needs. Ambitious engineering projects, decorative fountains, and private villas have contributed to the development of communities in these areas despite geographical challenges, difficult terrain, and adverse climates [79].

The analysis of the locations reveals clear climatic differences among them. Marrakech and Tabriz, situated in the northern hemisphere, experience extreme temperatures, while Nasca, located in the southern hemisphere, presents distinctive climatic conditions. These climatic disparities, including relative humidity and precipitation, play a crucial role in water scarcity in these regions and their hydraulic systems, as they share arid climate classifications. For instance, in the southern regions of Morocco, an arid Saharan climate is observed, hosting valuable oasis ecosystems threatened by rapid desertification, irrational exploitation of water resources, and inadequate agricultural practices, which exert significant pressure on groundwater [3,5,80,81].

Through an exhaustive analysis of rivers in the different studied cities, which supply water for agriculture, various forms of distribution along the basins have been observed, ranging from high to transition zones. The close relationship between rivers and the feeding of groundwater bodies has been highlighted, demonstrating the importance of this connection for water supply in these areas. These three systems exhibit significant connections with the rivers that supply the nearby city in the study area. This connection is also evident in the filtrating galleries of Alto Lerma, Mexico, where groundwater in the Lerma River basin plays a fundamental role in the region’s development, being part of the exploited aquifer for potable water supply in the local populations and industrial establishments in the area [82]. Thus, an important connection is established among these three elements: rivers, groundwater bodies, and ancestral hydraulic systems, all of which contribute to the water supply in the city adjacent to the study area.

7. Conclusions

The importance of the use of ancestral water resources in extreme conditions and in desert places was evaluated using efficient techniques and deep knowledge of the population in the behavior of groundwater.

The design of the puquios shows the use of winds with the objective of taking advantage of the slope of the underground flow in the galleries, contributing to the efficiency and functionality of the hydraulic system. Also, in the case of Khettaras and Qanats, they have a slope of 10% to 13%, which improves the distribution, functioning, and flow of water.

According to the analysis, it is observed that Nasca and Marrakech share similarities in their soils, which allow water retention and texture, while Tabriz is characterized by a finer texture and a greater water retention capacity. This attribute potentially improves the stability and durability of the ancestral system by minimizing the effects of erosion and wear of the most eroded material.

According to the analysis, the pre-Inca culture used advanced construction techniques to address erosion caused by the flow of groundwater, using stable elements in both the vertical and horizontal planes through a lintel system that could withstand soil pressure. Additionally, they used materials such as river stones to ensure proper seating and improve adhesion.