**2.1 Irrigation water quality**

Irrigation water quality is important for two reasons for irrigation engineers. The first , depending on the quality, irrigation method and irrigation system components are determined, the needed additional equipment lead to an increase in total cost of the system. The second, water quality affects adversely plant growth and soil fertility after the system operates. Irrigation water characteristics are examined in three groups; physical, chemical and biological (Wilko & Short, 2007).

#### **2.1.1 Physical properties**

In the physical properties, suspended matter is one of the most important features. Suspended matters in natural waters are usually composed of plaques erosion, parts of organic matter and

Irrigation 301

degree that it meets the quality regulations and communiqués criteria. In case of irrigation with waste waters, it is essential to identify an irrigation method and program that will no cause pollution of clean water as a result of deep seepage or runoff. Especially before using bacteriological contaminated waste water for landscape irrigation, the size of the area, population density, pollution degree of water must be analyzed very well (Surampalli & Taygi, 2004). Drip irrigation method should be preferred to sprinkler irrigation in order to minimize the damages to the people around since water is applied to the plants through atmosphere in sprinkler irrigation and to prevent black logs on the plant during irrigation of polluted waters. If sprinkler irrigation method is required to be applied, irrigation will

Plants, like all living things require water to sustain their lives. In order to fulfill the basic functions, enough water is needed in the soil containing roots. Otherwise, plant growth decline and deaths occur in later stages. Evapotranspiration (ETc) is consisting of two basic elements. These are: transpiration through stoma of plant leaves and evaporation of open surface of the soil around the plant. Many ways including direct and indirect ways are used in determination of ET. However, reference evapotranspiration (ET0) are used as preprojecting factor reference. A mathematical relationship is used for this purpose as given

ETc=ETo\*kc (1)

ETc is calculated based on plant that is taken as reference in ETo. This plant is usually alfalfa or meadow pasture. There are many improved equations to calculate the reference Evapotranspiration. These include Penman FAO modification, Penman Montheith, Hargraves, Blaney Criddle and Class A evaporation tank etc. (Tekinel and Kanber, 1988)**.** 

The second factor affecting the Evapotranspiration is crop coefficient. Crop coefficient is defined as a ratio of ETc to ETo. Crop coefficient varies depending on factors such as plant type, age, growth period, soil moisture etc (Allen et. al., 1978). Grass plant is usually grown in the fields of landscape. Although this plant has many types, its kc value has been reported

Surface water resources are not distributed in a homogeneous way in many regions of the world, irrigation is applied in these areas in order to ensure vegetation sustainability due to irregular and inadequate rainfall. Irrigation water requirement is calculated with the help of

IR: ETc-Peff (2)

possibly minimize the health and environmental effects in windless conditions.

**3. Quantitative characteristics of irrigation water** 

**3.1 Evapotranspiration** 

Where,

kc: crop coefficient

to vary between 0.7 and 1.05.

the following equation.

**3.2 Net irrigation requirement** 

bellow. (Doorenboos and Pruit, 1977):

ETc: Evapotranspiration of the crop, mm ETo: Reference evapotranspiration, mm

planktons (Ayyldz, 1990). Suspended matters are one of the most important things because they could cause obstructions in emitters in the sprinkler and drip irrigation. This kind of water should be filtered appropriately and then should be given to the system.

#### **2.1.2 Chemical properties**

The most important chemical properties in terms of irrigation is pH, the amount of solid matter dissolved in water (electrical conductivity), sodium adsorption ratio (SAR), residual sodium carbonate (RSC), Na % and amount of boron. pH is a measure that shows the acidity or alkalinity of water and it is required to be between 6.5 to 8.0 in irrigation water. The amount of dissolved solids is the degree of salinity in irrigation water. The degree of salinity in irrigation water is expressed as electrical conductivity (Ayyldz, 1990). Salt in the irrigation water is important in terms of physical and chemical properties changes of the water and soil, making toxic and physiological effects on plant. Most water of acceptable quality for turfgrass irrigation contains from 140 to 560 µmhos/cm soluble salts (Cockerham & Leinauer, 2011). It is necessary to be careful when irrigating with highly salinity waters, especially higher than 2250 µmhos/cm.

Sodium is important in terms of blocking soil colloids and prevents the formation of a available air water balance in the soil. Ratio of sodium ion on total cations (Na %) and its ratio to magnesium and calcium ions (SAR), the two indicators are used in evaluation of irrigation waters. In order to create a condition of suitable soil in the root zone of the plants, the percentage of Sodium should not be more than 50-60%.

Sodium adsorption ratio is another important factor. As the increase of the sodium amount in the irrigation water breaks its physical properties, it is also important in terms of making alkaline the soil (Smith, 1996). In the analysis of irrigation water, due to the higher total salt concentration the higher effect of SAR will be, while estimating the effects of the SAR, the total concentration in the irrigation water should also be considered.

Boron is another important criterion, which is usually not available as element in nature, it is usually found as sodium borate or calcium borate. More than 0.5 mg/l in irrigation water may cause toxic effect on plants.

#### **2.1.3 Biological properties**

Because of bacteria threaten the human health, care should be paid in the use of such polluted water in areas where people live. As specified in the regulation of water quality, the fecal coliform values up to 200/100 ml of water can be used for irrigation purposes (Harmancioglu et. al., 2001).

#### **2.2 Reuse of waste water in irrigation**

Water is polluted physically, chemically and bacteriological by various wastes especially in industrial and agriculture as well as household use. Water contaminated in such ways is called waste water. In the regions where clean water resources is limited or water charges are high, irrigation water requirements are tried to be solved with the use of waste water contaminated with industrial and specially with urbane use (Novotny et. al., 2010). However it should be remembered that the waste water can be used for irrigation purposes if it is treated to the

planktons (Ayyldz, 1990). Suspended matters are one of the most important things because they could cause obstructions in emitters in the sprinkler and drip irrigation. This kind of

The most important chemical properties in terms of irrigation is pH, the amount of solid matter dissolved in water (electrical conductivity), sodium adsorption ratio (SAR), residual sodium carbonate (RSC), Na % and amount of boron. pH is a measure that shows the acidity or alkalinity of water and it is required to be between 6.5 to 8.0 in irrigation water. The amount of dissolved solids is the degree of salinity in irrigation water. The degree of salinity in irrigation water is expressed as electrical conductivity (Ayyldz, 1990). Salt in the irrigation water is important in terms of physical and chemical properties changes of the water and soil, making toxic and physiological effects on plant. Most water of acceptable quality for turfgrass irrigation contains from 140 to 560 µmhos/cm soluble salts (Cockerham & Leinauer, 2011). It is necessary to be careful when irrigating with highly salinity waters,

Sodium is important in terms of blocking soil colloids and prevents the formation of a available air water balance in the soil. Ratio of sodium ion on total cations (Na %) and its ratio to magnesium and calcium ions (SAR), the two indicators are used in evaluation of irrigation waters. In order to create a condition of suitable soil in the root zone of the plants,

Sodium adsorption ratio is another important factor. As the increase of the sodium amount in the irrigation water breaks its physical properties, it is also important in terms of making alkaline the soil (Smith, 1996). In the analysis of irrigation water, due to the higher total salt concentration the higher effect of SAR will be, while estimating the effects of the SAR, the

Boron is another important criterion, which is usually not available as element in nature, it is usually found as sodium borate or calcium borate. More than 0.5 mg/l in irrigation water

Because of bacteria threaten the human health, care should be paid in the use of such polluted water in areas where people live. As specified in the regulation of water quality, the fecal coliform values up to 200/100 ml of water can be used for irrigation purposes

Water is polluted physically, chemically and bacteriological by various wastes especially in industrial and agriculture as well as household use. Water contaminated in such ways is called waste water. In the regions where clean water resources is limited or water charges are high, irrigation water requirements are tried to be solved with the use of waste water contaminated with industrial and specially with urbane use (Novotny et. al., 2010). However it should be remembered that the waste water can be used for irrigation purposes if it is treated to the

water should be filtered appropriately and then should be given to the system.

**2.1.2 Chemical properties** 

especially higher than 2250 µmhos/cm.

may cause toxic effect on plants.

**2.1.3 Biological properties** 

(Harmancioglu et. al., 2001).

**2.2 Reuse of waste water in irrigation** 

the percentage of Sodium should not be more than 50-60%.

total concentration in the irrigation water should also be considered.

degree that it meets the quality regulations and communiqués criteria. In case of irrigation with waste waters, it is essential to identify an irrigation method and program that will no cause pollution of clean water as a result of deep seepage or runoff. Especially before using bacteriological contaminated waste water for landscape irrigation, the size of the area, population density, pollution degree of water must be analyzed very well (Surampalli & Taygi, 2004). Drip irrigation method should be preferred to sprinkler irrigation in order to minimize the damages to the people around since water is applied to the plants through atmosphere in sprinkler irrigation and to prevent black logs on the plant during irrigation of polluted waters. If sprinkler irrigation method is required to be applied, irrigation will possibly minimize the health and environmental effects in windless conditions.

## **3. Quantitative characteristics of irrigation water**

#### **3.1 Evapotranspiration**

Plants, like all living things require water to sustain their lives. In order to fulfill the basic functions, enough water is needed in the soil containing roots. Otherwise, plant growth decline and deaths occur in later stages. Evapotranspiration (ETc) is consisting of two basic elements. These are: transpiration through stoma of plant leaves and evaporation of open surface of the soil around the plant. Many ways including direct and indirect ways are used in determination of ET. However, reference evapotranspiration (ET0) are used as preprojecting factor reference. A mathematical relationship is used for this purpose as given bellow. (Doorenboos and Pruit, 1977):

$$\texttt{ETc=ETo\*\&c} \tag{1}$$

Where,

ETc: Evapotranspiration of the crop, mm ETo: Reference evapotranspiration, mm kc: crop coefficient

ETc is calculated based on plant that is taken as reference in ETo. This plant is usually alfalfa or meadow pasture. There are many improved equations to calculate the reference Evapotranspiration. These include Penman FAO modification, Penman Montheith, Hargraves, Blaney Criddle and Class A evaporation tank etc. (Tekinel and Kanber, 1988)**.** 

The second factor affecting the Evapotranspiration is crop coefficient. Crop coefficient is defined as a ratio of ETc to ETo. Crop coefficient varies depending on factors such as plant type, age, growth period, soil moisture etc (Allen et. al., 1978). Grass plant is usually grown in the fields of landscape. Although this plant has many types, its kc value has been reported to vary between 0.7 and 1.05.

#### **3.2 Net irrigation requirement**

Surface water resources are not distributed in a homogeneous way in many regions of the world, irrigation is applied in these areas in order to ensure vegetation sustainability due to irregular and inadequate rainfall. Irrigation water requirement is calculated with the help of the following equation.

$$\text{IR:ETc-Peff} \tag{2}$$

Irrigation 303

closed pipes. The total quantity of the required irrigation water for each irrigation is

dg=dn/Ea (4)

It is an expression how many days elapsed between consecutive two irrigation. It can be

Due to heavy textured soils have greater water-holding capacity, the irrigation interval increases depending on the net irrigation water, and it decreases in sandy soils. In suitable soil conditions, as reducing by half the irrigation period of a week or ten day period of

The system capacity turned from water supply or irrigation duration is determined by the

Q=A\*dt/3.6\*T (6)

The way of irrigation water supplied to the crop root zone is called as irrigation method. In determining the irrigation method for use, soil and topographic features of the land, plant type, irrigation water supply, labor and technical skills conditions, facilities and operating costs and climatic data of region are factors that are needed to be considered. Basically, there are two groups as surface irrigation methods and pressurized irrigation methods. Surface irrigation methods are evaluated amongst the traditional irrigation methods and transmission of water is carried out with the help of energy provided through geographic height difference completely between the source and target parcels. The basin, furrow, border and uncontrolled

flooding irrigation methods are also involved in the surface irrigation method.

Ti: dn/Etc (5)

calculated by the following formula.

dg: gross irrigation requirement, mm, dn: net irrigation requirement, mm, Ea: irrigation application efficiency %.

**3.2.3 Irrigation interval** 

Ti: irrigation interval, day

**3.2.4 System capacity** 

Q:System capacity, L/s A: Irrigated Area, da T: Irrigation duration, h

**4. Irrigation methods** 

following formula.

Where,

ETc: evapotranspiration mm /day

Ea can be taken as 0.8 when the planning for sprinkler irrigation

determined with the help of the following formula.

dn: Net irrigation requirement for each irrigation, mm

irrigation, increasing irrigation efficiency can be achieved.

Where,

Where,

Where, IR= Net Irrigation requirement, mm ETc= Evapotranspiration, mm Peff= Effective rainfall, mm

The irrigation requirement occurred as a result of evapotranspiration can be meet by precipitation. Precipitation usually occurs in the form of rain in plant growing season. Therefore, in determining of irrigation water requirement, the rainfall used by plants must be taken into account. However, a certain amount of rainfall is used by plants through surface runoff and deep infiltration. The rainfall that is stored and used in the root zone of the plants is called effective rainfall.

#### **3.2.1 Net irrigation requirement for each irrigation**

In the irrigation scheme, in the event that evapotranspiration is not met with natural rainfall, the deficit should be met with irrigation. In a operation unit, the quantity of irrigation water is determined with the help of the following formula.

$$\text{dn} = (\text{FC-WP})/100)^\* \text{Ry}^\* \text{??}^\* \text{D} \tag{3}$$

Where,

dn**:** Net irrigation requirement for each irrigation, mm FC= Field Capacity, % WP= Wilting point, % Ry= Allowable soil water deficit % (0.3-0.4 can be taken for turf) t= bulk density, g/cm3 D= the root depth, mm

As shown in the equation 3, there are two basic features affecting quantity of irrigation water. These are soil and plant features. In the irrigation area, due to the fact that the plants in each operation unit have different evapotranspiration, the quantity of the bounden irrigation water is also changing. At the same time, depending on soil characteristics, the water-holding capacity representing the rest quantity of water between field capacity and wilting point, also changes while water-holding capacity is low in a sandy soil, it is high in a clayed soil. In contrast to the sandy soils, due to the high water-holding capacity of clayed soils, more irrigation water will be applicated. Therefore, in the preparatory stages of recreation areas, when creating operation units, ensuring the collection in the same area of the same kind of plants and the fields with the soil structure will provide great convenience to users in the operation of irrigation system. This planning is the only way to ensure the uniform water distribution in the system without causing the overuse of excess water. In case of ignoring this situation, in the operation units that exits different plants or they are nested, some plants will be overwatered, and also some plants will be watered insufficiently. In addition, depending on soil characteristics, while the pondings may be in some areas, there will be losses of deep-seepage in some areas.

#### **3.2.2 Gross irrigation requirement for each irrigation**

Even in optimal projecting condition, there is no storage of all of the water in the root zone of plants. During the delivery and application of irrigation water, the water losses are experienced. It is considered that there is no delivery losses in water pipes transmitted with

The irrigation requirement occurred as a result of evapotranspiration can be meet by precipitation. Precipitation usually occurs in the form of rain in plant growing season. Therefore, in determining of irrigation water requirement, the rainfall used by plants must be taken into account. However, a certain amount of rainfall is used by plants through surface runoff and deep infiltration. The rainfall that is stored and used in the root zone of

In the irrigation scheme, in the event that evapotranspiration is not met with natural rainfall, the deficit should be met with irrigation. In a operation unit, the quantity of irrigation water

dn=(FC-WP)/100)\*Ry\*ϒt\*D (3)

As shown in the equation 3, there are two basic features affecting quantity of irrigation water. These are soil and plant features. In the irrigation area, due to the fact that the plants in each operation unit have different evapotranspiration, the quantity of the bounden irrigation water is also changing. At the same time, depending on soil characteristics, the water-holding capacity representing the rest quantity of water between field capacity and wilting point, also changes while water-holding capacity is low in a sandy soil, it is high in a clayed soil. In contrast to the sandy soils, due to the high water-holding capacity of clayed soils, more irrigation water will be applicated. Therefore, in the preparatory stages of recreation areas, when creating operation units, ensuring the collection in the same area of the same kind of plants and the fields with the soil structure will provide great convenience to users in the operation of irrigation system. This planning is the only way to ensure the uniform water distribution in the system without causing the overuse of excess water. In case of ignoring this situation, in the operation units that exits different plants or they are nested, some plants will be overwatered, and also some plants will be watered insufficiently. In addition, depending on soil characteristics, while the pondings may be in

Even in optimal projecting condition, there is no storage of all of the water in the root zone of plants. During the delivery and application of irrigation water, the water losses are experienced. It is considered that there is no delivery losses in water pipes transmitted with

Where,

Where,

FC= Field Capacity, % WP= Wilting point, %

t= bulk density, g/cm3 D= the root depth, mm

IR= Net Irrigation requirement, mm ETc= Evapotranspiration, mm Peff= Effective rainfall, mm

the plants is called effective rainfall.

**3.2.1 Net irrigation requirement for each irrigation** 

is determined with the help of the following formula.

dn**:** Net irrigation requirement for each irrigation, mm

Ry= Allowable soil water deficit % (0.3-0.4 can be taken for turf)

some areas, there will be losses of deep-seepage in some areas.

**3.2.2 Gross irrigation requirement for each irrigation** 

closed pipes. The total quantity of the required irrigation water for each irrigation is calculated by the following formula.

$$\mathbf{dg} \equiv \mathbf{dn}/\mathbf{E} \mathbf{a} \tag{4}$$

Where,

dg: gross irrigation requirement, mm, dn: net irrigation requirement, mm, Ea: irrigation application efficiency %. Ea can be taken as 0.8 when the planning for sprinkler irrigation

#### **3.2.3 Irrigation interval**

It is an expression how many days elapsed between consecutive two irrigation. It can be determined with the help of the following formula.

$$\text{Ti: } \mathsf{dn}/\mathsf{Etc} \tag{5}$$

Where,

Ti: irrigation interval, day dn: Net irrigation requirement for each irrigation, mm ETc: evapotranspiration mm /day

Due to heavy textured soils have greater water-holding capacity, the irrigation interval increases depending on the net irrigation water, and it decreases in sandy soils. In suitable soil conditions, as reducing by half the irrigation period of a week or ten day period of irrigation, increasing irrigation efficiency can be achieved.

#### **3.2.4 System capacity**

The system capacity turned from water supply or irrigation duration is determined by the following formula.

$$\mathbf{Q} \mathbf{=} \mathbf{A}^\* \mathbf{d} \mathbf{t} / 3.6^\star \mathbf{T} \tag{6}$$

Where, Q:System capacity, L/s A: Irrigated Area, da T: Irrigation duration, h

#### **4. Irrigation methods**

The way of irrigation water supplied to the crop root zone is called as irrigation method. In determining the irrigation method for use, soil and topographic features of the land, plant type, irrigation water supply, labor and technical skills conditions, facilities and operating costs and climatic data of region are factors that are needed to be considered. Basically, there are two groups as surface irrigation methods and pressurized irrigation methods. Surface irrigation methods are evaluated amongst the traditional irrigation methods and transmission of water is carried out with the help of energy provided through geographic height difference completely between the source and target parcels. The basin, furrow, border and uncontrolled flooding irrigation methods are also involved in the surface irrigation method.

Irrigation 305



In sprinkler irrigation systems, rivers, lakes, well water, dam can use as a source of water.

In sprinkler irrigation system, water should be sprayed from the headings under a certain pressure. This pressure is called as a head-operating pressure. In addition in the system, depending on equipment used between water supply and irrigation area, in case of an extra pressure requirement due to the difference of levels with terrestrial and permanent head loss, this requirement is met by pumping station that will be installed on the system. The pump units can be electric or diesel engines. Centrifugal pumps are suited if the height between the pump and the water supply is less than 8 m if not deep well pumps

The head control unit that is located between the water supply and the delivery line, is composed of hydro cyclone, sand and gravel filter, fertilizer unit, mesh filter and pressure regulator from the pump to main pipe line. In addition, the components such as check valve, a shut-off valve, pressure gauge, water meter and the equipments such as the nipple, ell and

In areas where sprinkler irrigation systems are installed, the fertilization process can be carried out with the aid of a pump unit such as venture tubes or injection pumps, the fertilizer tank that will be placed in head control unit. Due to different fertilization requirements of different plants, this process is used more easily and effectively in areas

where there is especially the only type of plants such as grass fields.

Urban drinking water schemes and wells are generally used in Landscape irrigation.



Components of sprinkler irrigation system are given below.





**The disadvantages of sprinkler irrigation method** 


tee combining these components are involved.


windy conditions.

**4.1.1 Water supply** 

**4.1.2 Pump units** 

are suited.

**4.1.3 Head control** 

**4.1.3.1 Fertilization unit** 


The purpose of Irrigation planners is to re-increase the optimum level the decreasing water levels in the root zone with a minimum of irrigation water by using an efficient irrigation system. The pressurized irrigation methods are preferred than surface irrigation methods because of its need more less water and staff per unit area. In pressurized irrigation methods, water is transmitted via the pipe system from the source to the relevant parcels under a certain pressure. A pressurized irrigation system that will be installed in general, is composed of pump unit, control unit, the main pipe line, sub main pipe line, manifold, lateral and water emitters (Phocaides, 2007) (Figure 1).

#### **4.1 Sprinkler irrigation**

This method is the systems which water is supplied from the source such as stream, lake, dam, or drinking water system in the form of droplets sprayed through atmospheric air to the plant with the help of sprinklers (Ingels, 2003). These types of systems which are high degree-uniform-water distribution can be supplied with proper planning in all kinds of soil conditions and slope and rough terrains. Sprinkler irrigation is the most suitable and common method for landscape irrigation. It is suitable for irrigation by using any type of water source on the condition of using appropriate equipment. Sprinkler irrigation elements: water supply, pumping unit, control unit, the main canal, sub main canal, manifold, lateral and sprinkler heads. Sprinkler irrigation method is the most preferred method in landscape irrigations. Advantage and disadvantage of sprinkler irrigation method are given below.

#### **The advantages of sprinkler irrigation method**


Fig. 1. Main components of pressurized irrigation systems

The purpose of Irrigation planners is to re-increase the optimum level the decreasing water levels in the root zone with a minimum of irrigation water by using an efficient irrigation system. The pressurized irrigation methods are preferred than surface irrigation methods because of its need more less water and staff per unit area. In pressurized irrigation methods, water is transmitted via the pipe system from the source to the relevant parcels under a certain pressure. A pressurized irrigation system that will be installed in general, is composed of pump unit, control unit, the main pipe line, sub main pipe line, manifold,

This method is the systems which water is supplied from the source such as stream, lake, dam, or drinking water system in the form of droplets sprayed through atmospheric air to the plant with the help of sprinklers (Ingels, 2003). These types of systems which are high degree-uniform-water distribution can be supplied with proper planning in all kinds of soil conditions and slope and rough terrains. Sprinkler irrigation is the most suitable and common method for landscape irrigation. It is suitable for irrigation by using any type of water source on the condition of using appropriate equipment. Sprinkler irrigation elements: water supply, pumping unit, control unit, the main canal, sub main canal, manifold, lateral and sprinkler heads. Sprinkler irrigation method is the most preferred method in landscape irrigations. Advantage and disadvantage of sprinkler irrigation



lateral and water emitters (Phocaides, 2007) (Figure 1).

**The advantages of sprinkler irrigation method** 

through appropriate design and arrangement.

Fig. 1. Main components of pressurized irrigation systems

**4.1 Sprinkler irrigation** 

method are given below.

surface irrigation.


#### **The disadvantages of sprinkler irrigation method**


Components of sprinkler irrigation system are given below.

## **4.1.1 Water supply**

In sprinkler irrigation systems, rivers, lakes, well water, dam can use as a source of water. Urban drinking water schemes and wells are generally used in Landscape irrigation.

#### **4.1.2 Pump units**

In sprinkler irrigation system, water should be sprayed from the headings under a certain pressure. This pressure is called as a head-operating pressure. In addition in the system, depending on equipment used between water supply and irrigation area, in case of an extra pressure requirement due to the difference of levels with terrestrial and permanent head loss, this requirement is met by pumping station that will be installed on the system. The pump units can be electric or diesel engines. Centrifugal pumps are suited if the height between the pump and the water supply is less than 8 m if not deep well pumps are suited.

#### **4.1.3 Head control**

The head control unit that is located between the water supply and the delivery line, is composed of hydro cyclone, sand and gravel filter, fertilizer unit, mesh filter and pressure regulator from the pump to main pipe line. In addition, the components such as check valve, a shut-off valve, pressure gauge, water meter and the equipments such as the nipple, ell and tee combining these components are involved.

#### **4.1.3.1 Fertilization unit**

In areas where sprinkler irrigation systems are installed, the fertilization process can be carried out with the aid of a pump unit such as venture tubes or injection pumps, the fertilizer tank that will be placed in head control unit. Due to different fertilization requirements of different plants, this process is used more easily and effectively in areas where there is especially the only type of plants such as grass fields.

Irrigation 307

causes to be defected by loading excessively over system units. Also, irregular, inadequate or high pressure cause breakdown of corresponding water diffusion and unnecessary additional irrigation. Pressure regulator generally used in control unit may be used before

Operating units generated in pressurized irrigation systems have possibility of being operated on time and duration which is desired by the help of control units. As well as control units are used in garden-type small irrigation area having only one operation, the more developed ones can be done by means of a program which can operate several operations at the same time if requested. Electrical or wireless models of control units are used in areas in which electrise is problematic (Orta, 2009). If required, program used can regenerate irrigation program again by help of rain, wind and soil sensors placed in control units. Shut-down of system can be obtained by itself on the instant of rain through programming rain shutoff on control units. Also, it can prevent irrigation in case of soil`s having enough moisture by programming soil moisture sensors (Cardenas-Lailhacar et. al., 2008). Moisture sensors to be installed within working area provide more economic use of

Fig. 3. Control unit panel having 8 Station used in landscape irrigation Systems

pipes. But submain and manifold are also included in great irrigation area.

Consist of pipes which deliver irrigation water from pump units to water emitters. A typical delivery line consists of main and lateral pipes and equipment which are used to tie those

They are pipes which transmit water from control units of water to submain canals if any, or to manifolds. Main canals carrying highest flow in system are manufactured as PVC and PE. Generally, 63-160 mm diameters are used depending on the size of system. They are the

manifolds in main systems if required.

water, generating irrigation program.

**4.1.3.6 Control units** 

**4.1.4 Delivery line** 

**4.1.4.1 Main line** 

pipes in which frictional loss is at the most.
