Irrigation Systems and Techniques in China and Mesoamerica

It is clear throughout antiquity, and according to Vaclav Smil in his book Energy and Civilization: A History, that energy and technology are shaped by geographic contexts, history, and culture. The geography, or physical features of a territory, help shape what types of technology would be most effective to solve a given issue, or how much energy can be expended and gained as a result. In the case of history, it follows that civilizations would change and improve technology to find more energy efficient ways to accomplish tasks. Culture is also a major factor that molds technology, as certain techniques may be used for reasons regarding shared beliefs and traditions. A comparison between farming techniques, more specifically irrigation in China and Mesoamerica, can explain this. Geography, history, and culture had a major effect on the vastly different irrigation systems developed in these regions. These technological differences had a direct connection to net energy amounts, which would increase over time as the result of innovation.

In order to describe how geography, history, and culture affected irrigation systems, the very process of irrigation must be explained. Irrigation is defined as “the watering of land by artificial means to foster plant growth”. Gravity fed irrigation is most energy efficient, as no human labor is required to bring water to the surface. Instead, only human labor is needed to control the water flow by building canals or other structures. However, in places where streams are not readily available, water must be brought to the surface using lifts powered either by animals or men. Early civilizations quickly learned that this was no easy task. According to Smil, “the total seasonal need [of water] is commonly about 1,000 times the mass of the harvested grain”. Mechanical devices were invented to solve this problem, including counterpoise lifts, paddle wheels, and other similar innovations. The energy cost of this type of work was staggering, from not only the sheer amount of water required but also from the work needed to raise the water from underground wells and the weight of water itself.

Chinese Irrigation Systems and Techniques

The irrigation system in China has lasted over 2000 years as a result of dredging and dike repairs. China’s irrigation is made possible by the riverbeds found there, as well as seasonal rainfall. Water from these riverbeds is channeled and subdivided through use of rock structures created by the peasants farming the land. A major example of this is the Dujiangyan, the oldest irrigation system in the world. Water flow is regulated by dykes, with the primary building ingredient being rock filled baskets made of woven bamboo. Depending on the season, the dykes allow a different portion of water from the main river to be diverted to the Chengdu plain, where crops are grown. Geographically, the mountainous terrain of China helped to shape irrigation, as well as the frequently flooding rivers. Rice in specific was grown on levelled terraces, where the surface area of farmable land could be maximized. The various man-made structures built on the Minjiang River, where the Dujiangyan is built, help to control the flooding water and irrigate the nearby Chengdu plain.

While geography played a huge role in the Chinese irrigation systems, history and culture also affected the ability to innovate and improve irrigation. Historically, Chinese peasants have eaten very little meat in their diets; grain constituted approximately 90% of their food energy. Therefore, it was essential that crop yields were high to sustain this high density of people, which would only increase over time. Smil notes the importance of leadership with regards to the money and manpower involved in irrigation building and maintenance. He says “none of these requirements could be met without an effective central authority. There was clearly a synergistic relationship between China’s impressive large-scale water projects and the rise, perfection, and perpetuation of the country’s hierarchical bureaucracies”. The governor at that time, Li Bing, was in charge of the project, and used around 10,000 men to accomplish the task. China’s strong bureaucratic power has been a major influence on technology and innovation.

There was also a large underlying tradition that contributed to the success of the Dujiangyan. According to Bangben Peng, “the deep reason behind the success of water culture in ancient Shu lies in its continuous developed and deepened ideal of consistency and harmony with nature….Taming flood by dredging it is the embodiment of the ancestors’ realization in the nature of water and natural laws”. The techniques of dredging and diverting water flow instead of blocking it shows that the Chinese had a desire to irrigate and control water in more natural and conservatory ways. Although China did not achieve political unity until the Qin dynasty, it was clear through their natural use of materials and strategic designs that the Chinese were culturally unified in their respect for “the harmony of man and nature”. This harmony had a major effect on the planning and construction of irrigation projects such as the Dujiangyan.

Mesoamerican Unique Ways to Effectively Irrigate Crops

The Mayans, for example, varied their techniques specifically for the terrain of the area they lived in. For instance, upland Mayans utilized terraces made from rock in order to prevent erosion and conserve water. Lowland Mayans, on the other hand, worked with canals and elevated fields to avoid flooding their crops from seasonal rainfall. Managing water was so important because, according to Smil, one third of the population of people near the basin of Mexico were dependent on irrigation and water management for their food.

The Aztecs developed a more unique irrigation technique. They built fields elevated about 1.5 to 1.8 meters above the water level of lakes, called chinampas. The geography of the land was perfect for these fields, as these productive fields were previously unused swampland. The fields themselves were built with mud, crop residue, grasses, and weeds. The perimeter was built with trees. Because no animals were used in their creation, the collective construction of these chinampas required a minimum of “70 million man-days of labor”. Chinampas are considered a type of sub-irrigation, because the platforms are built above the water level. However arduous the fields were to create, they proved to be beneficial, and could yield at maximum 4 times more than non-irrigated land. 10 p-d, or five-hour person days, of work with a wooden stick was required to build each field, which were about 27m^2 of area.

The building and use of these Mesoamerican irrigation systems is directly related to the history and culture of the people. Peasants spent no less than 200 days a year producing enough food for their family, and could spend no more than 100 days on water and irrigation projects. In a similar way to the Chinese, it was essential for the people of Mesoamerica to coordinate and extensively plan their efforts to increase crop yield by use of irrigation systems. Chinampas were constructed between AD 1426-1427. According to Arco and Abrams, “Itzcoatl is credited with ordering the religious hierarchy and instituting regulations such as the taxation system whereby food, goods and labour were extracted from the population”. Under this ruler, planning and construction of these sub-irrigation systems was conducted.

Another factor that contributed to the building of chinampas was aggressive Aztec expansion. It would be impossible to build these fields without access to the southern lakes, which were previously controlled by other native peoples near Tenochtitlan. According to Townsend, “the majority of lake communities were deemed primary targets of Aztec expansion in a strategy designed to control the economically valued southern lakes as quickly as possible'. With military control of these lakes, the Aztecs could grow more food for their people, which in turn would help them to continue their conquest of Mesoamerica. An estimated 2.4 million chinampa fields were constructed as a result of this expansion.

There is no question that geography, history, and culture are major factors that contribute to technology and energy. Irrigation systems in China and Mesoamerica are examples of this. In both China and Mesoamerica, the terrain of the land allowed for different irrigation techniques to be used, such as dykes and chinampas. History and culture were major elements in both civilizations as well. Strong central authorities were necessary to guide peasants in massive hydraulic projects, and centuries of tradition would help mold techniques used. I believe that in order to accurately analyze the technology and energy utilized in these societies, it is of utmost importance to consider all three of these components. The geography, history, and culture of a place are ingredients that define civilizations, and therefore have an inherent connection to the resulting technologies and energies that can be efficiently employed there.

Works Cited

• Arco, Lee and Elliot Abrams. An Essay on Energetics: The Construction of the Aztec Chinampa System. Antiquity. 2006.
• “Irrigation.” Merriam-Webster.com. Merriam-Webster, 2019.
• Peng, Bangben. Dujiangyan Irrigation System: A Case of East Asia Local Knowledge with Universal Significance. Higher Education Press and Springer-Verlag. 2008
• Sanders, W.T., J.R. Parsons, and R. S. Santley. The Basin of Mexico: Ecological Processes in the Evolution of a Civilization. New York: Academic Press. 1979.
• Smil, Vaclav. Energy and Civilization: A History. MIT Press, 2017.
• Townsend, R. The Aztecs. London: Thames and Hudson. 1992.
• Vaillant, G. C. Aztecs of Mexico: Origin, Rise, and Fall of the Aztec Nation. Harmondsworth: Penguin. 1966.