In the United States nearly 64.1 percent of water drawn from groundwater sources is used for irrigation.
There are primarily four sources of water that we can use for irrigation. These are groundwater, surface water, atmospheric water and ocean water. The most widely used source for irrigation is surface water in the form of rivers, lakes, and streams. Ocean water is least utilized for irrigation purpose other than in the Middle East where water desalination plants are installed.
Large area irrigation systems are quite prevalent in the western part of the United States. Some large area irrigation systems are as follows:
- Furrow Irrigation: In this irrigation system the plants are grown in raised beds and the water is distributed throughout the field using canals, unlined ditches or furrows. These furrows are interconnected and so water can move from the first bed to the last bed. The furrows can be dug using hand tools, plow or tractor. Water is transported to the furrows via plastic or aluminum pipes. This method of irrigation is not popular in the US because it is labor intensive and places increased demands on the water sources.
- Sprinkler Irrigation: In this irrigation system an overhead sprinkler is piped to one or more central locations within the field and the water is distributed by the means of overhead high pressure sprinklers. Sometimes, sprinklers are also installed below ground level. The sprays are not designed to operate in pressures more than 30 psi as misting problems might occur.
- Drip Irrigation: In this irrigation system the water is delivered to the root or near the root drop by drop. This is the most water efficient method of irrigation. You need low water pressure for this type of irrigation and the distribution can be adjusted uniformly throughout the field.
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