Irrigation Water Management

Irrigation Systems

1-General

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Approximately 9 million irrigated acres in California

• Surface Irrigation ~ 70%
  • Surface irrigation is also called "gravity" irrigation sometimes, but this can be confusing, because sprinkler and microirrigation are also called "gravity" irrigation when the pressure is supplied by a high elevation water source gravity fed to the irrigation system. Because of this potential confusion, the term "gravity" irrigation is best avoided.
• Sprinkler Irrigation ~ 24%
• Microirrigation ~ 6%
• Subirrigation ~ less than 1%

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Categorization of Irrigation System Types

• Un-Pressurized Irrigation Systems
  • Surface
  • Subirrigation
• Pressurized Irrigation Systems
  • Sprinkler
  • Microirrigation

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Trends

As the table below shows, the trend is toward pressurized forms of irrigation, away from surface irrigation. Part of the increase in pressurized systems is due to newly developed lands, and part due to conversion of previously surface irrigated lands. The main reason for the trend is the better control of the water that is possible with pressurized systems.

Change in irrigated area by system type, 1986 data  Sprinkler  + 16%  + 325,000 acres  Microirrigation  + 6%  + 25,000 acres  Surge Irrigation*  * + 8,000 acres  Other Surface Irrigation  - 5%  - 335,000 acres * Surge Irrigation was a new form of surface irrigation, using pressurized pipe and automatic control valves to deliver water to a gated pipe, which dispensed water into furrows as a traditional gated pipe system would, but with cycles of heavy inflow and no inflow, instead of a steady intermediate flow. There was virtually no surge irrigation in California prior to 1986, so the percentage change cannot be calculated.