Prepared By :

Mohammed Abdullah Ali

Introduction

Irrigation of agricultural crops in UAE mainly depends on the underground water . The average of salinity in the underground water used in irrigation reaches between 400-4500 P /million in some areas and it may exceeds this figure in other regions .
The virtual agricultural areas were increased during the past years to 245000 hectare, however the scarcity of water is a great restriction that hinder extending the agricultural areas due to the severe shortage of the underground water .

The need for the underground water for irrigation purposes has been greatly increased recently as a result of scarcity of the average of rainfall which reached to 120 mm per year, led to the occurring disturbance in water balance and consequently diminished the water level and water salinity particularly during the years of high drought .
The government of the UAE has given all priority and exerted tangible efforts to conserve water resources .Therefore, it has initiated to find out the alternative methods than the traditional irrigation systems .

Studies and research have been conducted as well as comparing the best methods successfully used in other countries that have similar climate conditions .
It was found that the dripping system is preferable to irrigate vegetables, Jungles and forestry . The sprinkling irrigation is favorable for forage and
Crop fields and bubbles system is compatible for fruit trees and ornamental plants .
The modern irrigation systems are covering about 82% of the total cultivated areas in UAE and the traditional systems of irrigation have become confined to irrigate some of old farms .
Studies and research are still in process in order to enrich the efficiency of irrigation systems so as to reduce water consumption .

Integrated management of irrigation requires the following :

• Flexible design of irrigation system.
• Using high quality materials and Equipments .
• Professional net installation according to specifications and designs.
• Continuous management ,operating irrigation nets.
• Periodical maintenance for irrigation nets.

The advantage of proper design of irrigation nets

Flexible operating and maintenance. The even distribution of irrigation waters in the field. Non hindrance of machinery operations and other services. Provides the plants with the actual needs of water needs.

Irrigation systems in UAE

Firstly: Dripping irrigation system

Advantages of Dripping systems:

1. It avails the best utilization of water through minimizing the percentage of evaporation , lost water during run off and deep leakage .
2. The remarkable growth of plant and agricultural production as well due to continuous existence of moisture around the roots area .
3. Displacement of salinity due to repeated times of irrigation .
4. Better supply of chemicals and fertilizers .
5. Controlling weeds plantation due to the small wet able surface area.
6. It can work properly in the irregular topographical areas .
7. Minimizing energy consumption as compared to sprinkler system .
8. Minimizing the laboring hands by 70% .
9. Possibilty of conducting other agricultural operations in the dry areas without any affect to the performance of the system .
10. Performance will not be affected by winds or during day and night .
11. Dripping system reduces exposure to infections and diseases on wet plants since the plant cover always remains dry .

Dribblers:
The main part of the dripping irrigation system where water can be supplied to plants in a fixed and low average . They are the smallest parts used for water discharging from the dribblers pipes into the soil, either as connected or a separated part installed in the pipe .

Dribblers should have the following specifications :

1. Continuous and regular discharge .
2. Dribbler cross section should be relatively large to avoid blockage .
3. Resistant to sun heat .
4. Easy for cleaning .
5. Difference in discharge of Dribblers due to change of pressure should be very slight .
6. The main problem confronts the dripping irrigation system is the blockage of Dribblers which is having direct relation with the nature of irrigation water since blockage is mostly resulted by organic and non organic materials and precipitating salts or other materials .

Blockage of Dribblers could be avoided by:

1. Field observation : regular testing and observation of the dripping system is necessary to find out any defect or blockage in the performance of drippings , leaking in the pipes or a failure in the related equipments since proper maintenance requires regular manual and automatic cleaning and observation once week .
2. Installing the proper filters to avoid drippers blockage which will lead to irregular distribution of irrigation water.

Filters shall have the following specifications :

• Capability of filtering equivalent quantities of water according to irrigation averages .
• Filters shouldn't cause any change of pressure .
• Availability in the market in reasonable prices and rust proof as well .
• Easy for maintenance , installation and disassembling .

3. Washing of the irrigation net: This process could be conducted through opening and closing the ends of the main and sub divide pipes, and to be rinsed with the beginning of the season .
4. Chemical treatment of irrigation water : Through using Sulfuric and Hydrochloric acids to reduce chemical precipitations and Phosphoric acid is used for water treatment and a fertilizer, while Chlor is used to restrain the activity of Bacteria .

Secondly: sprinkler irrigation system:

Sprinkler irrigation system is mainly used to irrigate the crop fields, Forages, green areas in the gardens and parks ,as well to irrigate some of vegetable crops which are planted closely provided that the irrigated water should be of law salinity .
Sprinkling system conception is based on the quick pushing of water through the sprinkler opening which will help spreading the water and fall down like rain fall drops, and the size of these drops is depending on the diameter of the sprinkler orifice and the pressure .

Sprinkler irrigation system is divided into three groups are:

The fixed systems : the main and the sub- by pipe lines, are fixed and buried under the soil . Sprinklers are fixed in the surface pipes , and irrigation operations could be controlled by switching on and off the main and the secondary valves . The moving systems : This kind of sprinklers could be moved later to irrigate another cultivated areas and the sprinkler gun is an example of the fixed systems because all parts are immobile except the gun . The moving systems:Moving mechanically by wheels either in a straight lines or in circulation. The axis irrigation system is the most popular one which consists of arms that circulate over an axis on purpose of irrigating big areas .

Advantages of sparkling irrigation systems:

Hard topographical lands can be irrigated without leveling . Sprinklers do not need water filtering due to the their wide orifice . Sprinklers do like air conditioner in the field which gives better environment in the field . Minimizes hand power . Minimizes laboring cost .

To ensure utilizing the sprinkler irrigation system by:

• Designs shall ensure regular supply of irrigation water .
• Seeking the proper specifications of sprinklers which include diameter ,circle of witness and angle of elevation .
• Accurate information of wind directions and speed in the area .
• Selection of sprinklers shall is connected to:
• Kind of crop
• Specifications of soil
• Quantity of discharged water with the penetration ratio to avoid surface running of water .
• The distance between sprinklers and their lines .

Thirdly : Bubblers irrigation system :

Advantages of this system:

1. Reduces performance cost as it irrigates trees together in a short period of time.
2. Water of medium salinity can be used for irrigation by this system .
3. It helps continuous wash of salts away of roots area.
4. It helps roots spreading .

The necessity for maintaining modern irrigation systems:

Maintenance in the suitable time is necessary to improve and reduce the performance cost and sudden disorder which will affect irrigation schedule .
Full maintenance shall include, pumping units, generators, filtering equipments, fertilization, water measuring ,valves, control sets, pipe line nets and irrigation tools.

The following preoccupations should be followed :

• Maintenance at the beginning of each season.
• pipes testing to avoid leaking.
• Checking up the valves.
• Check the metal pipes .
• Washing the main and sub –by pipes, filters and sprinkler opening.
• The internal parts of filters should be tested to find out any damage or rust resulting from the precipitated remains of fertilizer and salts.

It was found necessary to continue irrigation operations for 15 minutes at least after the fertilization works had been finished to ensure dissolving of the salts and fertilizing tanks.
If the farmer is using larger tank in irrigation, he must keep it always clean to avoid growing of algae which will close the to control unit and the pipe line net .Therefore, periodical cleaning is necessary.

Maintenance during the season :

• It is very important to ensure that all equipments are working properly.
• Testing all electrical conductivity, filtering tool and control equipments.
• Testing the internal filtration items every month.
• Washing the fertilizing tools and clean the internal parts from any precipitated materials or rusting .
• Chick the condition of valves especially non ret rated valves .
• To chick the quality of the electrical ports to ensure being isolated.
• Chick the availability of water in the well before operating the water pump .
• Periodical pressure measuring in the ends of the main and the sub- by pipe line is necessary to find out any disorder or defect in the pipes.
• Flow out water strongly in the pipe lines (Dribblers, fountains, sprinklers ) and conduct washing the irrigation net once a month .