If there is one thing that is essential to a culture’s survival it is the availability of water. A constant water source is necessary not only for drinking but for irrigating crops as well. In the arid conditions found in the Andes Mountains, how was it then that some ancient cultures such as the Chavin and the Incas were able to flourish?
Archaeologists have now found evidence that several ancient cultures built canals in order to irrigate crops and carry a steady supply of water to areas where water was not normally available. Four canals have been found that date from between 5400 and 6700 years ago, showing evidence that South America was the sight of irrigated agriculture long before any other region in the Americas.
The canals were found on the south side of the Nanchoc River in an area known as the Zana Valley. The valley is an area where some of the oldest civilizations have been found in South America. The canals were shallow and quite narrow. They were lined with pebbles and larger stones and measured anywhere from less than one mile to more than two miles long. The fact that these canals were found near the remains of stone hoes, charred plants and other examples of agricultural life strongly points to the fact that the canals were used to water crops.
Evidence shows that the canals were not built all at one time. The earliest canal seems to have been built when there was a higher amount of rainfall. Water travelled along the canal all year long. Other canals were not used as frequently and were even abandoned at one point. Scientists think that this may have meant the site was abandoned at some point.
Instead of fighting gravity and working against their surroundings, it was clear to archaeologists that the canals used positioning in order to allow gravity to move the water from its source to the crops. The slopes allowed the water to travel easily and reliably to the crops in order to make sure they had the water they needed in order to flourish.
Before the canals were found, scientists were finding it difficult to explain how a complex society based on agriculture could flourish in such an arid area. Some societies flourished in South America as much as 5,000 to 6,700 years ago and without a steady supply of water, this would have been incredibly difficult to accomplish.
The water that travelled along the canals was drawn from small streams. Crops had been planted in areas that were lower than the rivers although they were not naturally wet. This showed that the civilizations which utilized the canals were organized enough to notice their surroundings and use the geography to their advantage, rather than simply choosing random areas to plant their crops.
Although the canals only date back by as much as 6,700 years, many scientists believe that there may have been an organized system of irrigation as much as 9,000 to 10,000 years ago although they feel that evidence of these very early canals will be hard to find.