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 was necessary for the Inca to thrive and expand along much of the coast of Peru. 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 freshwater 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 floodwaters were carried to huge masonry reservoirs for storage, channeling water to their cities and religious centers.
Early accounts
The first recorded accounts of Incan water transportation structures came from Spanish conquistadores in the sixteenth century. 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."
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 or Sacred 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.
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. 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.
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 suggest 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.
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.