The earliest form of irrigation dates back at least 8,000 years, and the technique remains an important part of successful agricultural practices across the world. Here is a brief history of irrigation from the earliest days until modern times.
The earliest known systems of irrigation began in 6000 BC in Egypt and Mesopotamia. In Egypt, the Nile flooded for a few months each year, and the waters were diverted to the fields to allow farmers to grow crops where otherwise they would be unable to do so. In 3100 BC, a large irrigation project was built, which involved the construction of dams and canals up to 20 kilometres in size.
However, the flooding was uncertain, and high flows could wash away dikes and flood entire villages, whereas low flows would not provide the crops with enough water.
In Mesopotamia, the Tigris and Euphrates floodwaters were used in the same way. The Sumerians dug canals in what are considered the first ever works of engineering. It is thought that canals could be used for up to 1,000 years before being replaced.
Terrace irrigation is an ancient technique that was used all over the world, including in China and India, but it was used especially in the Americas. The Zana Valley in Peru provides an example of this technique, and remains of irrigation canals have been found here that date back to 4,000 BC, which are the earliest systems in the Americas that we know of. However, the technique could have been used even earlier than this.
Irrigation in Sri Lanka dates back to about 300 BC during the reign of King Pandukabhaya. A very complex system of underground canals was used, and this is the first place where artificial reservoirs for storing water were built in an incredible feat of engineering. In fact, they were so well designed that they still exist to this day.
Two systems of irrigation were used in North America, which are known as the Chaco and Hohokam systems. The Hohokam system was used by the Hohokam people in Arizona, and the Chaco system was used by the Anasazi in New Mexico.
The Hohokam people built canals in the early centuries of the first millennium, whereas the Chaco system dates to about 900 AD. This also used canals to divert water into fields and reservoirs in the San Juan basin.
There are many other examples of irrigation systems that were used in different parts of the world. One that stands out is the Assyrian irrigation system. This utilised tunnels that brought water from underground sources in hills and carried it down to lower ground, and once it was used it spread into North Africa.
Irrigation in Mexico dates back to about 600 BC. It involved the construction of storage dams where blocks were joined together and canal systems were developed to carefully control the water.
The Romans also used irrigation in Britain as early as 2,000 years ago. Only recently, an irrigation system was discovered in Cambridge that may have been used for growing grapes or asparagus. The Romans used dams and reservoirs for irrigation, and they then distributed the water via channels. Romans also constructed grand aqueducts to transport water not just for farming but for baths and homes.
Many devices have been invented to assist with irrigation throughout the centuries. The Shaduf was one of the first devices, which was used in Ancient Egypt. This consisted of a large pole that was balanced on a crossbeam. It had a bucket at one end and a counter weight on the other, and the farmer would pull the rope to lower the bucket into a river then swing the pole around and empty the bucket in the field.
The Qanat was a device used as early as 800 BC, and is one of the oldest irrigation methods that is still used today. It was invented in Persia (modern-day Iran), but it was also used in other areas including North Africa, Asia and China. Qanats consisted of vertical wells in hills that were connected to sloping tunnels. These tapped into groundwater that was directed away and used for farming. They were hard to build, but they provided a constant source of water for many years.
The Nori was a water wheel that was used by the Romans in North Africa at about the same time as the Qanat. The wheel had clay pots attached to it, and it was either turned by animals or by a moving stream.
Irrigation has come a long way since it was first invented thousands of years ago. Modern irrigation systems are very advanced, and there are various systems in use around the world.
Surface systems are still in use today and involve the water being moved across the surface of a farming area to wet the soil. This is one of the oldest techniques used, and it is similar to irrigation through the flooding of rivers, which dates back thousands of years.
Localised irrigation is the name used to describe various types of irrigation methods used today. It involves water being distributed under pressure to an exact location, and it includes drip irrigation and sprinkler irrigation. This allows greater accuracy and control over the distribution of water, which is essential for many types of modern-day intensive farming.
Sub-irrigation is a more advanced form of irrigation that is widely used around the world. This involves artificially raising the level of the water table below the ground, which then moistens the soil from below rather than applying water onto the soil from above. It is a popular technique in many places around the world, and it is also used in greenhouses.
In-ground systems are widely used in commercial settings. This is when the irrigation system is hidden in the ground so that the area looks cleaner and the pipes and other devices do not get in the way.
Irrigation demonstrates the ability of humans to control our world through the use of innovative techniques. It has been essential for the successful growing of crops right across the world for thousands of years, and it remains so to this day. Irrigation techniques may continue to develop, but the basic process of artificially directing water towards agricultural land has remained a mainstay of farming for thousands of years and has allowed humans to dominate their environment wherever they live.