Nasca Aqueducts

Description

Nasca Aqueducts are located in the province of Nasca, department of Ica, in the basin of Rio Grande, characterized by being a hydrographic system that only starts based on the rainfall that occurs in the mountains of the upper part of the basin, in the foothills of the central Andes, which give rise to intermittent water courses, which usually last only between three and four months each year (December to March).

The aqueducts are in the lower part of the basin, which is characterized by being a very dry desert belt, mostly flat although there are some sectors with complex mountainous reliefs. The desert is crossed by several rivers, but contrary to the abundance of water, these are channels with an irregular regime, where most of the year the water is scarce and in many cases there is a total drought with a prolonged duration. (ANA, 2010).

The shortage of water hindered the development of the desert settlers through centuries. To alleviate this situation, the inhabitants of the Nasca culture managed to use the water from the underground water table through a technological innovation, formed by underground aqueducts that operated through a system of filtering galleries. (Negro, 2018).

This system captures water filtration of the water table and leads it through underground and uncovered sections until it is stored in a “qocha” or reservoir to be then distributed to the crop fields (Gonzáles García 1942, Rossel Castro 1942, Schreiber and Lancho 1988, 2006). In the covered sections they built helical section eyes every certain stretch, in order to perform the maintenance and load the atmospheric pressure to the aqueduct to maintain the uniform flow regime, which does not cause erosion or sedimentation in the channel. It is a simple system apparently, but at the same time it is sophisticated, because it requires advanced technical knowledge and organizational capacity to articulate the collective efforts in its construction.

In its construction, two techniques have basically been identified: an open pit and a tunnel (Schreiber and Lancho 2006). The first consists of excavating a horizontal and open trench of variable depth, until it intersects the level of the groundwater, so in this way the water filtered in the trench, being through this led back to the surface and collected in a reservoir excavated in the ground (Negro, 2018). The base of the trench has an average of 1.00 meter wide opening towards the upper part, reaching 10.00 m in some cases, for which lateral berms were built, similarly to a step, which would serve to facilitate the access to the water channel and as an intermediate platform to accumulate sediments from annual cleaning.

The route has sinuous curves and sometimes with abrupt direction changes to control the speed of the flowing water transit. The boundary walls that function as containment, were built slightly inclined outwards to prevent landslides. Its walls were lined with river stones to prevent landslides and channel the water in only one direction, placed in such a way and without any binder, which have withstood the ravages of nature. The material used were the rounded stones of fluvial origin with very little mortar so that the groundwater could filter through them. Frequently, short channels were built, intersecting more or less at straight angle to the main channel, which are locally called "cangrejeras" (hollows) and which were intended to increase the amount of water that filtered from the subsoil to the main channel. (Schreiber and Lancho, 2006).

Most of the aqueducts were built with this technique and remain as such until today, although some have been filled to form the filled trench galleries. In the case of open channels, they can be up to one kilometer long until they reach the reservoir.

The second technique is more complex and has two variants. The Filled Trench Galleries, which were excavated as open-air channels and, after the construction of the lateral retaining walls, at a variable height, is placed a roof with stone slabs or trunks of the huarango tree. On top of the cover, the trench was filled with earthy material and stones. The galleries measure between 100 and 300 meters on average, but there are some others much longer that even pass under the current course of the rivers, as in the case of the Bisambra aqueduct.

The second variant are the Socavón Galleries, representing the most complex design for the level of knowledge required for its construction. They were built as if they were a tunnel excavated in the subsoil, in which case the lateral walls of rounded stones and the roof with stone slabs or alternatively logs of huarango, were placed as shoring while advancing with the perforation of the tunnel.

In these last two cases, vents called "eyes" or "chimneys" were built, which are located at variable distances between 5 and 20 meters following the course of the galleries, between which two types are distinguished: one of conical shape whose walls have retaining walls made of stone and a smaller one with a square shape whose walls are formed with huarango wood beams, which served for the entry of air and light and, at the same time, to access the interior of the galleries and perform the cleaning and maintenance work.

In those deeper underground tunnels, the vents are very deep and has a truncated-conical section, which can reach 15 m and have a rounded shape. In the vertical development they are gradually narrowing until the diameter to access the underground galleries usually does not exceed 1.00 meter on the side, acquiring a tendency towards the square. The access to the underground galleries is usually closed with huarango sticks covered by earth with a thickness of approximately 1.00 meter to prevent dirt, stones or other materials from falling inadvertently into the water channel.

According to the study of prehispanic settlement patterns, the construction of most of the aqueducts would have occurred during the development of the Nasca Culture, between the Early and Middle Nasca periods, that is, between the years 300 and 500 AD. known for the creation of the complex designs of geoglyphs and lines that occupy extensive areas of the desert areas of the region, known as the Nasca and Plapa Lines and Geoglyphs. They also built the Cahuachi Ceremonial Center, the most important set built for ceremonial purposes and the theocratic capital of the Nasca culture. These are two examples of the level of technological and artistic development reached by this society, from achieving an adequate management of water in a medium where it is scarce.

Justification of Outstanding Universal Value

The Nasca Aqueducts form a unique hydraulic system in America in terms of design, construction technique, location, use and function. In this sense, its design and construction technique respond to the ability of human adaptation to a desert environment, where the need to obtain and properly manage the scarce water of the subsoil, enabled the development of a complex society, great exponent of outstanding examples of art and architecture.

This system was built in the middle of one of the driest and most arid desert territories of the world, where there is no surface water during most of the year. In this context, the water obtained by means of ingenious aqueducts serves not only for human consumption but also to irrigate the crop fields, with which fertile oases were created in the middle of the immense desert.

The Nasca Aqueducts were made based on advanced knowledge of geology and hydrology and since its construction, almost two thousand years ago, it has been used permanently by the societies that succeeded its builders and is still in operation until today.

The Nasca Aqueducts are an exceptional testimony of the adaptation and development of societies in desert areas of arid climate through the obtaining and management of water and the capacity of the man of antiquity to overcome adverse conditions, whose solutions can be applied to the climatic problem of our time.

Criteria (iii): Agriculture has always been one of the essential bases for the existence and development of civilizations throughout the world, being closely linked to the availability and management of water. The coast of Peru was a difficult territory due to its extreme aridity, where however several civilizations arose and took full advantage of the narrow productive valleys that are distributed in the coastal desert strip.

The Nasca Aqueducts constitute an eminently representative example of a hydraulic system developed in the coastal valleys of Nasca, Taruga and Las Trancas, which allowed the emergence and progress of various complex social formations such as Nasca that reached a high level of development and refinement, as well as various social formations that later occupied the area such as Huari, Ica / Chincha and Inca over almost 2000 years of prehispanic history, marking a dynamic and transcendent social process in the south coast of Peru. This last is particularly significant if it is taken into account that the south coast suffered, at different times, from long periods of drought that affected the societies established there, making of the aqueducts an indispensable resource to ensure the availability of water and enable agriculture as livelihood and prosperity of each civilization, a condition that would not have been possible in this arid environment without adequate infrastructure for obtaining and managing water. All this meant an organization and specialization of the work for the layout, construction and maintenance of the aqueducts, whose technology was used by the various social groups that made use of the hydraulic system, keeping it in constant operation until today.

Criteria (iv): The Nasca Aqueducts constitute an exceptional work of prehispanic hydraulic engineering used continuously by successive societies up to the present. They represent an important technological achievement aimed at resolving in a singular way the permanent problem of water scarcity in the area, destined mainly for irrigated farmland.

The aqueducts form a system of independent filtering galleries that are located parallel to the course of the rivers and their tributaries of the Nasca, Taruga and Las Trancas valleys where the main crop fields are located, but where there is no surface water for most of the year. Through the construction of channels or galleries with open pit and / or underground with very small slopes and retaining walls of rounded stone, it was possible to capture the water from the subsoil by filtering the groundwater, to bring it to the surface and accumulate it in qochas or reservoirs for later management and distribution. For the development of this hydraulic system it required great knowledge of the characteristics of the land as well as the management of water under certain particular conditions, producing an innovative method of catchment and conduction of water for irrigation of the land, according to the availability of material, characteristics of the terrain and climate.

The access to the water resource permanently throughout the year allowed the transformation of important extensions of the mentioned valleys located in the coastal desert strip of the province of Nasca, improving the conditions of the lands around the river beds, commonly dry almost during the months of low water levels (May to December), and even extending the areas of cultivation, turning them into fertile environments full of life throughout the year, suitable for the development of agriculture for the sustenance of important civilizations such as Nasca and other social formations like the Huari, Ica / Chincha and Inca, established during the more than 1700 years of existence of the aqueducts.

Statements of authenticity and/or integrity

AUTHENTICITY

The authenticity of the Aqueducts of Nasca is confirmed by references of the XVII century about its existence, describing it as a beautiful ditch whose current was diverted in a way contrary to the direction of the river "... because a river that passes through that valley brought very little water summer and the Indians suffered a lot of sterility in their fields, which many years in the mountains it rained little, they lost because of lack of irrigation. And with the aid of the canal, which was greater than the river, they enlarged the lands of labor in more than the same, and from then on they lived in great abundance and prosperity ". (Garcilaso de la Vega, 1609: 296).

The existence and characteristics of this hydraulic system are amply documented by various archaeological and historical investigations. Since the middle of the XIX century they were described by historians and travelers who attributed it to the Incas. (Regal, 1943). Subsequently, more detailed investigations were carried out, including those by Toribo Mejia Xesspe (1939), by Gonzáles García (1978), Alberto Regal (1943), the priest Alberto Rossel Castro (1942), Berghuber and Vogl (2005) and Sandra Negro (2018), where most of the aqueducts known to date are described and which many of these researchers have been able to identify from previous references.

The most complete studies are those of Katharina Schreiber and Josué Lancho (1988, 1995, 2006) whose archaeological research indicates that the construction of the system would have begun around 300 to 500 AD, during the development of the Nasca. Archaeological sites associated with them and the study of the settlement patterns of the time, indicate that the middle part of the Nasca valleys (where there is no surface water most of the year) began to be occupied at that time as a result of the construction of the aqueducts (Schreiber and Lancho, 2006).

Research shows that all aqueducts maintain their original condition in terms of their layout, disposition, form, use and function. Although some changes and modifications would have been made in the following periods, until the Colonial period, as part of a normal process of renewal and maintenance of the same, because the system remains in continuous operation although partial, to this day. The spare parts have been made with similar materials, considering that the trunks of the covered channels must be replaced every so often and the periodic cleaning necessary for their operation.

An exception is the Cantayoq Aqueduct, which was the object of restoration and valorization work in the 1970s by the Development Corporation of Ica (CORDEICA), where in addition to the restoration of the walls of the open pit canal some walls of the eyes or vents of its two branches were reconstructed. Similar cleaning and restoration works, but with less impact, were also carried out in the aqueducts of Orcona, Pangaravi, Ocongalla and Santa María. However, in all these cases, the layout and functionality of the aqueducts intervened remained intact.

INTEGRITY

The Nasca Aqueducts constitute a hydraulic system that, due to its importance in everyday life, both in the urban and rural areas, is periodically a subject to cleaning and maintenance work by the residents who live near them and the users of water for agricultural purposes. During the more than 1700 years since the beginning of its construction, this system continued in operation. However, during the XX century the expansion of modern occupation precipice the disappearance of some complete aqueducts or their branches, while others were abandoned and without proper maintenance lost their functionality.

There is a registry of 41 aqueducts located in the valleys of Aja, Taruga, Tierras Blancas, Nasca and Las Trancas (see table No. 1). Unfortunately, with the passing of time, several have disappeared or have been notoriously modified. For example, in 2003, from the 37 described in the works of Schreiber and Lancho, several of them were dry, deteriorated or not in use in that year (Berghuber, 2005).

Despite this, many aqueducts, as well as the system as a whole, maintain intact their attributes that show it as a sophisticated hydraulic complex. Being a system that remains in operation, it can be said that the system maintains its integrity and despite the years that have elapsed, they are in relative good condition. The operational length of the aqueducts is over 9.5 kilometers, managing to irrigate more than 3,000 hectares of land. (Berghuber, 2005).

With regard to legal protection, the Ministry of Culture in application of the General Law of the Cultural Heritage of the Nation, Law No. 28296 is responsible for the protection of archaeological cultural assets. In this sense the Office of Coordination of Nasca was created, to favor the application of the Management System for the Cultural Heritage of Nasca and Palpa, that began the placement of milestones of delimitation of the intangible area and has been carried out cleaning works and restoration in the aqueducts of Achaco, Ocongalla, Majoro and Santa María, applying technical and documented procedures that contribute to ensure the preservation and integrity of the property. Likewise, the proposals for its declaration as Cultural Heritage of the Nation are being prepared.

For its part, the water resource obtained by the aqueducts is regulated by Law No. 29338, Water Resources Law and the National Water Resources Management System composed of several institutions of the national government and regional and local governments as well as the organizations of agrarian and non-agrarian users; operating entities of the hydraulic sectors and peasant communities and communities.

The integrity of the Nasca Aqueducts is assured due to the fact that most of them are in a good state of conservation, in the process of delimitation and have been the object of a detailed and exhaustive research that attest to the authenticity and integrity, despite that some parts of them have been renovated or restored to preserve their original function.

Comparison with other similar properties

In the Andean world, there are outstanding examples of water management for various purposes. One of the best exponents of the sophistication is the Archaeological Complex of Tipon, an Inca architectural complex composed of palaces and temples, with a large stone aqueduct that distributes the water in the different sectors of the complex and creates several sources of great beauty. However, unlike Tipon, the aqueducts of Nasca stand out for their need to deal with the scarcity of water, obtaining it from the depth of the soil in an extremely dry environment. This characteristic is more striking if one considers that the coastal site was built approximately a thousand years before the Cusco’s one.

As for the properties of the region inscribed on the UNESCO World Heritage List, the Padre Tembleque Hydraulic System, located in Mexico, represents an important hydraulic work built in the XVI century, using construction methods based on European knowledge and the traditional Mesoamerican techniques; whose design, materials and environment is totally different from the solutions designed by the ancient people of Nasca, based on the filtration and transfer of water through underground and uncovered channels.

The only good in the world, comparable to the Nasca Aqueducts, is the Persian or Qanats canals of Iran, 11 of which are inscribed on the UNESCO World Heritage List since 2016. It is a system of canals underground that capture the water from the aquifers at the top of the valleys and transport them through tunnels, with a series of vertical access wells, often many kilometers away, until they reach the crop fields. This system, which still works until today, also includes resting areas for workers, water tanks and hydraulic mills. They were built in the desert areas of Iran around 1000 BC. and from there, they spread to other regions of the Near East, reaching Egypt and China. With the expansion of the Muslim Empire, it came to Spain and it is estimated that thence to the New World.

Like the Nasca Aqueducts, the construction of the Qanats began with the excavation of a vertical well to a known aquifer. Upon reaching the water source, the horizontal drilling of the tunnel that had to carry the liquid to its destination was made. Since the original source was always located at higher altitude, the Qanats was slightly inclined and the water flowed by the effect of gravity without needing to be pumped. The quantity could not be controlled and depended on the water table of the spring. Every 30 meters of travel, approximately, a new well was made from the surface to have access to the water, to guarantee the ventilation, to be able to remove the surplus land and to carry out maintenance tasks. When the qanats arrived in the designated city, a large cistern allowed to store and give public access to water.

To that effect, the Qanats of Iran and the Aqueducts of Nasca represent similar solutions developed independently, by societies that flourished in environments of extreme aridity.