Incan aqueducts

The Incan aqueducts refer to any of a series of aqueducts built by the Inca people. The Inca built such structures to increase arable land and provide drinking water and baths to the population. Due to water scarcity in the Andean region, advanced water management allowed the Inca to thrive and expand along much of the Pacific coast of South America. Such structures, some of which survive today, show the advanced hydraulic and civil engineering capabilities of the Inca.

The water came mostly from nearby rivers, but was also brought down from fresh water springs on mountains. The ancients discovered that if they diverted certain amounts of water from rivers, then they didn't have to worry about scarce rain and drought and they could also stimulate plants to grow faster by getting enough water in time. Workers dug tunnels through mountains and cut channels into cliffs to complete the project.

In seasons when too much mountain snow melted, the flood waters were carried to huge masonry reservoirs for storage, channeling water to their cities and religious centers.^[1][2]

Early accounts

The first recorded accounts of Incan water transportation structures came from Spanish conquistadores in the 16th Cenjosetury. One such explorer was Pedro Cieza de León. In his published chronicles detailing his travels through Peru, he noted seeing a large wall as he headed east from Cuzco, which scholars argue he was referring to the aqueduct at the Piquillacta archeological site. Cieza writes:

"Along this road there is a very large, broad wall, along the top of which, according to the natives, ran pipes of water, laboriously brought from some river and piped in with the forethought and care they used in building their irrigation ditches."^[3]

Noted American archeologist Ephraim George Squier noted several aqueducts during his exploration of Peru in the late 1800s, including those that watered gardens on the terraces of the Yucay Valley, north of Cuzco. He also recorded an account of the ruins of a sixty-foot high aqueduct in the foothills of the Andes near Lima.^[4]

Machu Picchu

Machu Picchu, the most famous and well preserved of Incan archeological sites, contains a complex aqueduct system. Construction of Machu Picchu began as an estate for nobility around the mid-1400s under Emperor Pachacuti. Incan engineers in Machu Picchu were able to use an ingenious stone collection system to increase the yield of the perennial spring that normally only had substantial flows as mountain snow melted in the warmer months. Without this innovation, the population of Machu Picchu would have been unsustainable. While the area received enough rainfall for agricultural production, there were few freshwater sources for domestic use. Water had to travel 749 m (about half of a mile) to reach the city center.^[5] The Inca exhibited a large degree of technological prowess in their careful gradation of the aqueducts. By cutting the canals out of one stone, lining canals with rock, and filling joints with clay, the Inca were able to reduce water loss due to seepage.^[6]

The water from this stream provided water for sixteen fountains, lending an additional visual and auditory aspect to life in Machu Picchu. Those fountains served as water sources for those houses not directly provided with water from the canals, but also were places of worship and ceremony. Those fountains are notable because they suggests that the flow of water was integrated into the city's planning at a very early stage, which demonstrated that the Inca had a very advanced concept of city planning and resource management.^[7]

Moray

Moray is an archeological site approximately halfway between Cuzco and Machu Picchu. The site is noted for its three unusual depressions of concentric terraced circles. Vertical channels drop water from one level of the terrace to the next, creating a beautiful waterfall-like effect. Unlike Machu Picchu, Moray did not receive enough rain to sustain agriculture. Therefore, aqueducts were required for transporting water from the three surrounding springs. Reservoirs supplemented those aqueducts, which allowed for a steady flow of water despite the variable yields of the springs.^[8]

Tipón

Aqueducts can also be found at the archeological site at Tipón. Located thirteen miles east of Cuzco in the Cuzco Valley, this ensemble of ruins was once an estate for the Incan elite and nobility. The aqueducts of this area are set atop walls that predate the Incan occupation of the area. Scholars believe these walls to have been built by the Wari civilization. After the Inca took control of Tipón in 1400CE, Emperor Vircocha sent engineers to survey the site. Those engineers reinforced the existing Wari wall by using andesite^[9] and the characteristic Inca technique of mortarless masonry.^[7] They also improved the three existing canals. The Inca then created a trough on the top of the wall, which moved water from surface and ground sources to a nearby ravine, transferring over a thousand cubic meters of water. The ravine was then used for irrigation. The use of both ground and surface water, referred to as conjunctive use, is further evidence of the prudent use of the Inca's scarce resources.^[10]

This engineering marvel required complex topographical surveying and analysis, not unlike what would be done in a modern building project. This project depended on the labor of the Incan citizenry, though no peasant builders would reside within the complex. The central Inca government levied no taxes on its people, except for labor requirements on construction projects, giving the Inca the human capital to back up their engineering expertise.^[11]

The aesthetic qualities of the Tipón channel system were striking.^[12] While the principal purpose of the canals was to provide the estate with water and sustain agriculture, Incan engineers also took into account how the water would look flowing through Tipón's many terraces. Waterfalls and drops are accompanied by fountains, which may have also held a ceremonial function.^[13]

See also

• Inca engineers

References