Aqueducts in Machu Picchu (Photo credit: maría josé vergara)

By: Juan Andres Cajiao, Raquel Baldeón, María José Vergara, and Isabella Ortega

Abstract:

This research paper was created by Colegio Menor 10th grade students in Quito, Ecuador, to investigate the engineering methods the Incas used to provide water for agricultural purposes and human use within Machu Picchu during the pre-Columbian era. Moreover, the students went to Peru in order to collect evidence to answer the research question they created. The paper will give insight of the historical background of the Incas and describe how they succeeded in planning and building an effective water system in Machu Picchu. Furthermore, the project will explain how the Incas deviated the channels for agricultural purposes and human use. The information for this research paper was taken from reliable databases such as journal articles in order to extract accurate and credible information. In addition, while the students were in Peru, they observed archeological sites and took pictures so they could analyze and study in more detail to answer their question. Finally, after analyzing all the evidence the student collected before and after the trip, they could come up with an answer to their question. Their results were that the Incas used downward slope, gravity and a water spring to build the water systems. Also, what was accomplished and discovered was that the Incas first searched for the water spring before building the cities.

Intipunko Machu Picchu Empire (Photo credits: Milagros Cortéz)

Research Question: What engineering methods did the Inca Empire utilize to provide water for agricultural purposes and human use within Machu Picchu?

The Incas, one of the most important and expansive pre-columbian cultures, situated in modern day Peru, flourished for around 100 years, from 1438 AD until 1532 AD. Water was so vital for the Incas that they had a God for its adoration called Mama Cocha. This precious resource was vital for them because their main diet sources were obtained from the production of crops. Consequently, the Incas constructed many canals, along with reservoirs, in order to provide and transport water in Machu Picchu. Since the Incas were great architects, they not only managed to feed the whole empire by cultivating crops, but they also distributed water to the population and fields. The amount of water needed in Machu Picchu for agricultural and human use was extraordinary, leading us to investigate how the Incas created their system to manage and supply water throughout Machu Picchu. This question allows for a narrow and meaningful analysis since there is a large amount of information regarding the construction of Incan aqueducts and canals. The Incas’ mobilization of water through their Empire was important since it guaranteed the sustainability of the food supply for their civilization. The efficient water management proves that the Incas were able to live comfortably, with a stable production of food and supplies, for around one hundred years until the arrival of the Spanish.

Aqueduct in Machu Picchu (Photo Credit: Isabella Ortega)

Hypothesis: The main engineering methods used by the Incas to provide water to Machu Picchu were aqueducts and canals which utilized high pressure to preserve velocity and thereby transport the water to terraces for irrigation and to baths for human use.

This hypothesis directly and fully answers our research question regarding what specific engineering methods were used to distribute water for both human consumption and agricultural use in the Incan Empire. Our hypothesis suggests that the main engineering method the Incas used to transport water was high pressure in aqueducts and canals. We predict high pressure maintained the velocity of water so it could get to the terraces for agricultural use and to the city of Machu Picchu for human consumption.

Aqueduct with dirty water in Machu Picchu (Photo Credit: Isabella Ortega)

Research Methods: To answer our research question, we used reliable academic journal articles written by experts on the hydraulic systems of Machu Picchu, first hand evidence, and reliable sources on the internet.

In order to answer our question, before going on the academic field trip, we complied academic journal articles written by experts on hydraulics. Our group researched trustworthy databases, such as EBSCO and Google Scholar, to guarantee the information used would be accurate and credible. We read the most noteworthy journal articles and extracted only the information relevant to answer our research question. Specifically, we cited Kenneth R. Wright and Jeff L. Brown’s work because they have studied Incan aqueducts in Machu Picchu.

In addition, while we were in Peru, we conducted field observations of archeological sites to analyze how the Incan aqueducts were built. The primary sources were analyzed and broken into smaller components, which allowed further and more detailed study of the topic. Furthermore, while in Peru, we carefully observed and took photographs of Machu Picchu’s aqueducts and interviewed tour guides and natives, asking about the engineering methods the Incas used to build their elaborate aqueducts. Between databases and interviews, we gathered important information about Inca water management.

Machu Picchu Drainage System (Photo Credit: Isabella Ortega)

Conclusions: The main engineering methods the Incas used to construct their aqueducts in order to transport water into Machu Picchu for human and agricultural use were gravity, a downward slope, and a spring of water on a hilltop.

We reject our hypothesis because high pressure is not the main engineering method the Incas used to provide water to Machu Picchu. Even though the Incas did incorporate pressure in the aqueducts they constructed, the evidence gathered does not entirely support our hypothesis. Our findings do not show the reliance on high-pressure we predicted. In fact, Inca engineers first searched for a spring from which water emanated before building Machu Picchu (Brown, n.d.). The Incas first searched for the spring of water so they could plan where the city was going to be and how the canals were going to deviate for agricultural and human use. The use of natural springs at high elevations and downward slopes in the aqueducts, rather than high pressure within their canals, force us to reject our hypothesis.

Kenneth Wright, an engineer from Wright Water Engineers, a private firm in Denver, ascertained that the water transported in the aqueducts of Machu Picchu came from a spring higher in the mountains. Water from a tributary basin and rainwater fed this spring, which the Incas then transported through large, stone-walled canals. These canals formed an aqueduct with a downward slope of 1% to 4.8% to transport water to the city center (Wright, Kelly, Zegarra, 2000). The Incas also built a stone pathway next to the canal so they had easy access for maintenance. This aqueduct then continued for 749 meters from the spring to Machu Picchu, relying on the channel’s downward slope and the force of gravity to move water into the city.

More specifically, the Incas utilized sixteen different channels to distribute water to Machu Picchu (Wright, Kelly, Zegarra, 2000). However, before water reached the city center for human use, these channels deviated some water to the agricultural area to irrigate crops. Since the Incas used a drainage system, Wright believes the Incas knew they needed to consume pure water (Wright, Kelly, Zegarra, 2000). This drainage system took the leftover water from the city to the terraces for additional irrigation. Furthermore, the Incas did not bathe with the same water they drank. As described, the Incas had different canals that served as drainage for dirty water and as transportation for pure, drinkable water. Wright and other researchers calculated that the water channels could transport up to 25 liters per minute (Brown, n.d.). On the dry months they function with 10 liters per minute, which is sufficient to sustain a population of 1,000 people maximum (Brown, n.d.). This proves the Incas had a water system which provided enough water to satiate their necessities.

Machu Picchu from a Hill (Photo Credit: Raquel Baldeón)

Our research not only provides insight into the sophisticated architectural techniques used by the Incas to construct their aqueducts, such as locating a reliable source of water before building Machu Picchu and using a specific downward slope to maintain water flow. The effective use of slope and water sources disproves a widely held theory for the abandonment of Machu Picchu, as archeologists previously believed that this city was abandoned due to lack of sufficient water. While Machu Picchu did indeed need a vast amount of water to satisfy the needs of this city, the Incas developed a system that supplied the whole city with sufficient water. As shown before, the abandonment of Machu Picchu due to the lack of water was not a sustainable theory since the Incas´canals carried enough water to support a large population. Without a doubt, the Incas employed sophisticated techniques in their water supply management for Machu Picchu.

Works Cited

Baldeón, R. (2017). Machu Picchu taken from a hill. [digital photo]. self-published.

Brown, J. L. (n.d.). Water Supply and Drainage at Machu Picchu. Retrieved February 23, 2017, from http://www.waterhistory.org/histories/machu/

Cortéz, M. (2017). Intipunko Machu Picchu. [digital photo]. self-published.

Ortega, I. (2017). Aqueducts with dirty water in Machu Picchu. [digital photo]. self-published.

Ortega, I. (2017). Machu Picchu Aqueduct. [digital photo]. self-published.

Ortega, I (2017).Machu Picchu Drainage System. [digital photo]. self-published.

Vergara, M.J. (2017). Machu Picchu [digital photo]. self-published.

Wright, K. R., Kelly, J. M., & Zegarra, A. V. (1997). Machu Picchu: Ancient Hydraulic Engineering. Journal of Hydraulic Engineering, 123(10), 838-843. doi:10.1061/(asce)0733-9429(1997)123:10(838)

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