What is irrigation

Irrigation water can come from groundwater, through springs or wells, surface water, through rivers, lakes, or reservoirs, or even other sources, such as treated wastewater or desalinated water. As a result, it is critical that farmers protect their agricultural water source to minimize the potential for contamination. As with any groundwater removal, users of irrigation water need to be careful in not pumping groundwater out of an aquifer faster than it is being recharged.

Top of Page. There are many different types of irrigation systems, depending on how the water is distributed throughout the field. Some common types of irrigation systems include:. Surface irrigation Water is distributed over and across land by gravity, no mechanical pump involved.

Localized irrigation Water is distributed under low pressure, through a piped network and applied to each plant. Drip irrigation A type of localized irrigation in which drops of water are delivered at or near the root of plants.

In this type of irrigation, evaporation and runoff are minimized. Sprinkler irrigation Water is distributed by overhead high-pressure sprinklers or guns from a central location in the field or from sprinklers on moving platforms. Center pivot irrigation Water is distributed by a system of sprinklers that move on wheeled towers in a circular pattern. This system is common in flat areas of the United States.

Lateral move irrigation Water is distributed through a series of pipes, each with a wheel and a set of sprinklers, which are rotated either by hand or with a purpose-built mechanism. Ancient civilization s in many parts of the world practiced irrigation. In fact, civilization would probably not be possible without some form of irrigation. The earliest form of irrigation probably involved people carrying buckets of water from wells or rivers to pour on their crops.

As better techniques developed, societies in Egypt and China built irrigation canals, dam s, dike s, and water storage facilities. Ancient Rome built structures called aqueduct s to carry water from snowmelt in the Alps to cities and towns in the valleys below. This water was used for drinking, washing, and irrigation. Modern irrigation systems use reservoir s, tanks, and wells to supply water for crops. Reservoirs include aquifer s, basins that collect snowmelt, lake s, and basins created by dams.

Canals or pipeline s carry the water from reservoirs to fields. Canals and pipelines, just like the ancient Roman aqueducts, often rely on the force of gravity. Pumps may also move water from reservoirs to fields.

Crops are irrigated by several methods: flooding an entire field, channeling water between rows of plants, spraying water through large sprinklers, or letting water drop onto plants through holes in pipes. Letting water drop onto plants through holes in pipes, known as drip irrigation , is considered one of the most efficient methods of irrigation. Drip irrigation focuses the water onto the plant itself.

Other methods can waste water by letting it absorb into the ground where there are no plants. Water can also evaporate into the air when sprayed through sprinklers. During the twentieth century, the amount of irrigated land in the world doubled.

An estimated 18 percent of the worlds cropland is now irrigated. This expansion has occurred mainly in Asia, Africa, and South America.

Even desert ecosystem s like those in Jordan use irrigation. Jordan uses a variety of irrigation techniques with groundwater from wells and aquifers. To help meet the worlds demand for food, more farmland and more irrigation may be needed. Many experts fear that the expanding use of irrigation in some areas will deplete aquifers, reducing the amount of freshwater available for drinking and hygiene.

The Aral Sea, in Central Asia, has been almost completely emptied by irrigation. In , the Soviet government decided that the two rivers that fed the Aral Sea, the Amu Darya and the Syr Darya, would be divert ed to irrigate crops of cotton, melons, and citrus in the deserts of Kazakhstan and Uzbekistan. Canals were poorly built, and much of the water went to waste.

Before large-scale agriculture was introduced in the s, the Aral Sea had an area of 68, square kilometers 26, square miles.

Today, the Aral Sea is three separate lakes, with a combined area of fewer than 17, square kilometers 3, square miles. The Aral Sea ecosystem has been nearly eliminate d.

The areas once-thriving fishery has been destroy ed. Huge fishing vessels now sit abandoned in the middle of the salty desert. Kazakhstan and Uzbekistan are working with environmental organizations to preserve what is left of the Aral Sea while still allowing farmers to irrigate their crops. It can also come from storage ponds made to collect high river flows or rainfall during winter. Pipes, channels and wells take water from its source to farms, vineyards and orchards. How much water is used depends on the type of crop, the soil in which the crop is being grown, and the amount of rainfall in that area.

Feeding the world requires a lot of water. In most countries, irrigating land uses more water than any other purpose. Water is essential for farmers to produce many of our daily food items. The availability, price and range of our food, particularly our fruit and vegetables, are all linked to irrigation. These places need irrigation to produce high-quality food.

In other regions the reason for irrigation may be to combat a particularly dry season a drought. It could also be to ensure high value food crops kiwifruit for example always have the right amount of water during an important growth phase. Irrigation is the artificial watering of land that does not get enough rainfall. Sometimes we use basic irrigation at home.

You might use a hose or sprinkler to water the garden. Large scale irrigation is where market gardeners, farmers, and orchardists apply water at important times.