HYDRAULICS_6

Design of Irrigation Systems

by

László Ormos

WATER HEAD

Water energizing:

1. By gravityThe water flows from tanks over the irrigated field.

2. By pressurizationThe water flows under pressure by pump into the water network.

Water sources:1. Open water bodies2. Underground water bodies3. Reclaimed sewage water

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Tasks for water head:

1. FiltrationImpurities in water must be filtered (sand, silt, clay, planktons, algae, etc.)

2. Pressure controlAdequate pressure has to be set for the required outlet quantity.

3. Flow controlThe outlet flow quantity must be controlled.

4. Control of fertilizationThe required quantity of fertilizers and feeding into the water must be supervised and controlled.

5. TimingThe irrigation intervals and outlet quantity of water must be controlled.

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1. FiltrationIn order to avoid clogging of water emitters, the water has to be filtered before approaching the emitter.Impurities in water can be classified by the followings:

• organic debris,• inorganic solid particles (sand, silt, clay, insoluble

materials),• organic living creatures (zooplankton, phytoplankton,

algae, bacteria, fungi, etc.)Surface water from open water bodies contains more impurities than underground water.

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Screen filters

External rough filterInternal fine filter

Drainage valve

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Disk filters

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Media filters

Filter media

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2. Pressure control

Pressure regulator: setting of required pressure in the irrigation network.

Pressure limiter: setting of maximum pressure permitted for the pump.

One-way valve: prevents the flow of water back from the irrigation network into the water network/spring.

Water meter: measures (and controls) the quantity of outlet water.

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3. Flow control

Semi-automatic control: it is combined with the water meter, irrigation time is setting and start by hand.

Full-automatic control: interval and irrigation time is switched by a preset electronic watch.

Computer control: interval and irrigation time, shift, andback-flushing is controlled by an irrigation computer.

Intelligent control: computer control influenced by the environmental circumstances, continuously.

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4. Control of fertilization

pH-control: equipment for setting the concentration of fertilizer by measuring the pH-

value.

EC control: equipment for continuous measuring the conductivity of outlet/drain liquid.

Fertilizer injector control: for mixing fertilizers with the outlet water by flushing tank,

Venturi- injector or electric driven chemical pump.

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5. Timing

Mechanical clock: must be set and start by hand.

Electronic switch: irrigation time and interval is set by hand, start of irrigation is automatic.

Irrigation computer: all the settings are programmed by on-board switches, or by PC with

remote control, and start is automatic.

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Hand-operated water head

with fertilization

Main valve

One-way valve

Inlet water

Outlet to Plot 2

Q

Pressure regulator

Water meterwith timer Outlet

to Plot 1

Valves to Plots

Filter

Venturi-injector

Fertilizer tank

Fertilizer valves

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Irrigation computer-controlled water head

Inlet water

Main magnetventil

One-way valve

Outlet to Plot 2

Pressure regulator

Water meterwith data output

Outlet to Plot 1

Magnet ventils to Plots

Q

FilterFilter with back- flush control

Waste watermagnet ventil

Magnet ventils for back-flush control

Irrigation computer

References

Azenkot, A.(1998):”Design Irrigation System”. Ministry of Agricul-ture Extension Service (Irrigation Field service), MASHAV Israel

Dr. Avidan, A.(1995):”Soil-Water-Plant Relationship”. Ministry of Agriculture Extension Service (Irrigation Field service), CINADCO,Ministry of Foreign Affairs, MASHAV, Israel

Sapir, E.-Dr. E. Yagev (1995):”Drip Irrigation”. Ministry of Agricul-ture and Rural Development, CINADCO, Ministry of Foreign Affairs, MASHAV, Israel

Sapir, E.-Dr. E. Yagev (2001):”Sprinkler Irrigation”. Ministry of -culture and Rural Development, CINADCO,Ministry of Foreign Affairs, MASHAV, Israel

Eng. Nathan, R. (2002):”Fertilization Combined with Irrigation (Fertigation)”. Ministry of Agriculture and Rural Development, CINADCO,Ministry of Foreign Affairs, MASHAV, Israel