Maintaining and Improving Irrigation Application Uniformity in Sprinkler and Drip Systems Burdette Barker, Utah State University (USU) Extension Irrigation Specialist Sheridan Stewart, USU Graduate Research Assistant Mark Nelson, USU Extension Professor, Beaver County
Introduction
The goal of most irrigation system design and management is to provide all plants in an irrigated area with equal access to water. Ideally, each plant should receive the exact amount of water it needs. If a field needs 1 inch of water for irrigation, all parts of the field should receive exactly that. The reality is not so perfect. It is practically impossible to apply the same quantity of water to all plants in an irrigated area, plot, or field (we will use the term field to refer to any of these). In other words, all irrigation systems have some nonuniformities in the water delivered. Instead of designing and managing irrigation systems to apply water 100% uniformly, the goal of irrigation system designers, manufacturers, and operators should be to maximize irrigation uniformity within practical and economic constraints. In this fact sheet, we explain major causes of uneven water distribution in sprinkler and drip irrigation systems and suggest ways to improve or maintain uniformity.
Basic Pressurized Irrigation System Components
Factors affecting irrigation uniformity are often related to the design and function of irrigation systems themselves. For this reason, it is helpful first to consider the basic components of a pressurized irrigation system. In this fact sheet, a pressurized irrigation system can be represented as having a water source, which may include filtration and a main distribution system, a manifold or submain pipeline, one or more lateral pipelines, and outlets with sprinklers or drip emitters (Figure 1). Water flows from the main system/source into a manifold or submain pipeline. This submain feeds a series of lateral pipes, sometimes many at once and sometimes only a single pipeline at one time. In the case of periodic-move systems, like hand lines and wheel lines, the lateral pipe is moved periodically from one lateral position to another across the field. In the case of a center pivot or lateral-move system, a single lateral moves mechanically across or around the field. Lateral pipes have multiple outlets feeding drip emitters or sprinklers.
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