In an earlier article I discussed the engineering marvel of the canal system in Arizona. Water management in the desert is paramount to living in the desert.
The original idea, however, came from the Hohokam Indians who lived in the Phoenix valley area for about 1450 years until 1500 AD. I guess I should say 1500 CE, but I'm just not ready to make that change.
The original canals were dug by hand by the Hohokam people and involved brilliant engineering. Some canals were 12 feet deep. The large canals branched off into smaller canals. In total, over 500 miles of irrigation canals were used by these people.
It is estimated that over 80,000 people lived in the area. They were able to live in the desert by irrigating over 110,000 acres with their canals.
Steady flow rate
They learned to make the canals wide at the mouth and then gradually taper, as they went to smaller canals branching off from the main. This enabled them to keep the flow rate steady. If they had not decreased size, the flow rate would have decreased as the distance increased from the source.
Steady flow rate is necessary for an irrigation system to work correctly. If the water flows too fast, it picks up sediment that will eventually block the canal. If the water flows to slow it, will not reach the final destination.
The Hohokam also avoided hills and valleys with the canals. This plus careful attention to the overall slope of the canals helped keep the flow rate consistent.
Why did the Hohokam leave?
There’s much debate about what happened to the Hohokam people, but they disappeared from the area and abandoned their canals around 1500 AD.
Some think they may have become the O’odham, another tribal group. O’odham traces are found mostly in southeastern Arizona. But their descendants now part of the Tohono O’odham, are still living in the area.
If this is so, we Arizonans, may be considered “illegal immigrants” more so than the ones getting scholarships to Prescott College. I’m sure most Native Americans would agree.
The canals survived
The canals however, were found abandoned in the 1860’s when a gold rush came to Arizona. Some enterprising individuals discovered the original purpose and usefulness of these canals and began reusing them.
Because of the ability to irrigate farm land, a settlement formed in 1868 known as Phoenix.
Currently the population of the Phoenix metro area is around 4.3 million. It is clear we wouldn’t be living here with water available if the early settlers hadn’t picked up on the knowledge of the Hohokam.
In addition, great planning and engineering has continued with water management in Arizona. Another article of mine, Arizona is a dry desert area, goes more in-depth about how the canal system is still being used to irrigate the state.