Designing a Drip Irrigation System

May 8, 2014 5:18 pm

Drip irrigation systems are designed for use in large scale horticulture and agriculture, where the cost of water; or the scarcity of water precludes sprinkler systems. In landscape projects, drip irrigation systems are normally designed where the project requires very unobtrusive watering, such as public spaces, or the planting is incorporated in hard-to-reach planters or troughs.

A drip irrigation system designed for field scale crops will generally use either a buried drip tape with a relatively thin wall disposable drip tape under crops of 1-3 seasons duration; or a thicker walled drip pipe either on the surface or sub-surface for longer duration crops such as vines or orchards. Sub surface drip systems are more economical in terms of water efficiency, but can be more prone to accidental damage. The design of the drip irrigation system needs to take into account the pressure losses in the pipework on long runs and also the topography of the field – sloping or undulating sites may need non-leakage design drippers to prevent water from leaking from the low points once the system has been turned off.

For landscape drip irrigation designs, thick walled drip lines would generally be used to water border areas – either pegged to the surface of buried under a mulch. Drip lines in a landscape setting are more prone to damage from maintenance staff, so a thick walled pipe is essential. Drip lines on larger beds would be spaced at approximately 0.5m apart across the bed. For smaller planters the drip irrigation system will need to be designed to bring water to each individual planter – generally using micro-bore drip pipe and drippers. Ideally on landscape projects the supply pipes for the drip irrigation system would be installed during the initial build process to ensure all of the supply pipework is hidden away.

To design a drip irrigation system a plan of the site is required along with information on the available water supply. For agricultural projects water can be taken from rivers, storage ponds or rainwater catchment areas such as farm buildings. For landscape projects mains water is generally used but water regulations generally require break tanks for back-flow prevention. The drip irrigation system can then be designed and pipe work sizes and quantities calculated.

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