Understanding an Irrigation System

Soluble nutrients move by water. Water is applied to containers by an irrigation system. The irrigation system must be functioning correctly for the water to be delivered efficiently. An understanding of water flow, pressure, friction and power will help you evaluate a system and prepare recommendations for improvements. There is an opportunity to achieve energy and water conservation, and improvement of the system. You must be able to determine the flow rate of water through nozzles or emitters or water meter, to calculate the amount of water discharged.

Non-uniform pressures in an irrigation system cause non-uniform application of water. Pipes that are too small, in the sense that the water must flow "fast" to supply the demand, have a high pressure or energy loss that is caused by the friction of water rubbing against the pipe walls. An increase in water velocity in a pipe causes more friction that results in a loss of usable pressure in the system.

The movement of water through an irrigation system is described by hydraulic principles. Terms such as flow, pipe cross-sectional area, water velocity, water pressure, friction loss, and power are described here to help in understanding, evaluating, and designing an irrigation system.

Several exercises will be included for self-study and review of the concepts presented in this section.