A Software Tool for Appropriate Design of Center Pivot Irrigation

8/19/2019 A Software Tool for Appropriate Design of Center Pivot Irrigation

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Sudan J. Agric. Res. : (2011), 17, 103 - 122 ARC, Sudan, Email: [email protected]

A software tool for appropriate design of center pivot irrigation

system

Hassan E. Alsayim1 and Amir B. Saeed2

Abstract

The experiment was conducted in the River Nile Sate, Sudan, to develop

a simulation model for designing a center pivot sprinkler irrigation

system. A Visual Basic 6.0 program was utilized in the model application

windows. The program was interactive to design a new system and/or

evaluate an already designed system. The crop water requirement and

the pipe size permitted to attain the target. The center pivot hydraulic

characteristics and its hardware specications were executed. Two center

pivot systems at Ras Elwadi farm and the Jordanian Bashair project wereused for model testing and verication during 2007/2008 season. With

respect to the hydraulic characteristics and hardware specications,

it was found that the center pivot system discharges were 318.8 m3hr-1

and 227.2 m3hr-1 for Ras Elwadi farm and Jordanian Bashair project,

respectively. The package of low drift nozzles (LDN) was 116 nozzles with

2.8 m spacing and 214 nozzles with 1.9 m spacing for Ras Elwadi farm and

Jordanian Bashair project, respectively. The ratio of actual to calculated

nozzle discharge and pressure were within the acceptable range of 0.82 to

1.13 and 0.97 to 1.17 for Ras Elwadi farm and 0.84 to 1.90 and 1.03 to 1.23for Jordanian Bashair project.

Introduction

Pressurized irrigation systems had been used since the early 1900s,

but the rst center pivot machine was developed in late 1940s. A center pivot

is a moving irrigation system with a lateral that rotates around a xed pivot

point. By mid1970s, the center pivot irrigation system had rapidly dominated

the new and expanding irrigation areas in the USA and the Middle East (Evans,

2001).Heermann and Kohl (1983) mentioned that the sprinkler irrigation systems

were designed to uniformly apply water to the soil at a rate equal to or less

than the soil intake rate. The design guidelines need to be either followed or

intentionally circumvented with appropriate design criteria when designing

and managing a center pivot irrigation system. Jorge and Pereira (2003)

depicted that a poorly designed irrigation system, even if well managed, often1 Department of Agricultural Engineering, Faculty of Agriculture, Nile Valley University, Darmali, Sudan.2 Department of Agricultural Engineering, Faculty of Agriculture, University of Khartoum, Shambat,

Sudan.


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Hassan E. Alsayim and Amir B. Saeed

results in crop yield losses and poor water productivity. Evans et al . (1997)

added that operating an irrigation system differently than assumed in the

design will alter the application rate and uniformity of coverage. Simulation

modeling of water, demand and supply is an essential analytical technique forassessing water management. Considerable research data for such conditions

and areas had been put into developed software to improve irrigation water

management. Field evaluation of sprinkler systems produced important

information to support the design in order to achieve better performance to

help farmers improve the management and maintenance of their irrigation

systems (Merriam and Keller, 1978). The eld data can easily be manipulated

through a computer model and effectively supported farmers to generate new

alternative solutions. To support design of sprinkler systems, several softwares

had been developed. Some models add graphical interfaces pay a particular

attention to the farm distribution network; others include topographical tools

to represent the elds under design. Examples of these models are:

The software SPRINKMOD developed by Andrae and Allen (1997) to

simulate pressure and discharges along the existing or newly designed

sprinkler irrigation systems.

The model ISADim developed by Abreu and Pereira (2002). It was

intended to design and/or simulate set sprinkler irrigation systems.

The model AVASPER developed by Jorge and Pereira (2003), aiming to

simulate and design sprinkler set systems.

This study was conducted to develop a center pivot simulation model (CPM)

for appropriate design of center pivot sprinkler irrigation systems.

Materials and Methods

Soil, crop and weather data for 30 years (1971 – 2000) were collected

from Atbara Meteorological Station, River Nile State. Three double ring

inltrometers were used for water inltration measurement. This data

represented the two different experimental sites of Ras Elwadi farm and the

Jordanian Bashair project, where center pivot systems were erected to irrigate

a forage crop (alfalfa) and a vegetable crop (onion) respectively. A computer

model designated (CPM) was developed during the rst season (2006/2007).

The model theoretical design characteristics were based on the collected data.

The CPM model accuracy was validated by its output from the data of season

(2007/2008) as compared with the actual system design criteria. The CPM

was executed using soil, crop and weather data to obtain the theoretical design

characteristics for the intended area and crops in the two sites. The obtained

results were compared with the actual data of the two systems in the two

sites.


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A software tool for appropriate design of center pivot irrigation system

Model development

The model CPM was developed using Microsoft Visual Basic 6.0 with

Service Pack 2 and included a database in Access 2000 and was run in

Windows. The program was interactive for designing a new system and/or

for evaluation of an existing system. In the design mode, computations were

performed iteratively until design constraints were met.

Firstly, the input data were prepared and the design criteria of the center

pivot system were executed later on. Finally, the system layout report was

printed out. However, in all cases, throughout the program, “click” means to

click the left mouse button and clicking “Previous” and “Next” buttons to get

backward to the previous window or upward to the next one.

When CPM was launched from windows, then the project information was

entered, and “Open project” button to open the project le for the center pivot

system design was chosen.

Field information and water supply

This option required data inputs of total eld area, diameter or short length

of the eld, elevation, water source and maximum available water volume

from source.

Soil data

This data were collected for the analysis of soil properties viz: calculation

of total available water, selection of soil inltration family, water depletion

ratio and calculation of readily available water. Computations were based onequations proposed by Withers and Vipond (1985) as follows:

Where: Taw

is total available water (cm), θfc is soil moisture content at eld

capacity (%), θwp

is soil moisture content at permanent wilting point (%), Rd

is relative density, Drz is root zone depth (cm), Dn is readily available water

(cm) and Mad

is water depletion ratio (%).


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Meteorological data

This window was divided into two parts. The rst part was for location of

the project, which included altitude, latitude and longitude. The second part

for ETo calculation using FAO Penman-Monteith equation (3) as modied by

Allen et al. (1998) or by using class-A evaporation pan method as proposed

by Jensen (1980), equation (4).

Where: ETo is reference crop evapotranspiration (mm d-1), ∆ is slope of the

saturated vapor pressure curve, Rn is net radiation ux (MJ m-2d-1), G is

sensible heat ux into the soil (MJ m-2d-1), γ is approximately 0.059 (kPa°C-1),

T is mean air temperature (°C), U2 is wind speed (ms-1) at 2 m above the

ground, es is saturated vapor pressure (kPa), ea is actual vapor pressure (kPa),

es - ea is mean daily vapor pressure decit (kPa), kp is dimensionless, pan

coefcient and Ep is pan evaporation (mm).

Crop water requirement

In this window (Fig. 1) the user can determine peak consumptive use for

four selected crops, irrigation interval and gross water depth. These computed

performance indicators are as proposed by Merkley and Allen (2007) using

the following equations:



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Where: ETc is crop evapotranspiration (mm day-1), Kc is crop coefcient, ETo

is reference crop evapotranspiration rate (mmday-1), II is irrigation interval

(days), Dn is readily available water in the root zone (mm), Dg is the gross

application depth (mm) and Ea is the application efciency (%).

Fig. 1. Dialogue box for crop water requirement determination.

System revolution

The system revolution design followed the approaches proposed byAl-Ghobari (2004). In this form the simulated parameters were number of

revolutions, water depth during one revolution, available irrigation time and

one rotation time. The following equations (8, 9, 10 and 11) were used for the

aforementioned calculations:



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( )Re ................................................................................................ 9 Dg

Dg v

Nrev

=

( ) ..................................................................................................... 11Ti

Trev Nrev

=

Where: Nrev is number of revolutions, Dg is gross water depth (mm), dgmax

is maximum water depth added without causing runoff (mm), Dgrev is waterdepth during one revolution, Ti is available irrigation time for one irrigation,

Trat is readily available time (%) and II is irrigation interval.

System discharge

System discharge design followed the methodology recommended by

Merkley and Allen (2007) as follows:

Where: Q is the system discharge (l s-1), K is 2.78, A is area (ha), D is gross

daily application depth (mm), F is frequency in days per irrigation and T is

operating time, generally 20-22 (hr day-1) during the peak use period.

Pivot lateral design

In the “Pivot lateral Design” window (Fig. 2), the output design criteria for

the system with one pipe size or two pipes size are lateral inner diameter andsystem discharge adjusted to the calculated diameter. The calculations were

carried out as proposed by Keller and Bliesner (1990) as follows:



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Where: d is inside diameter of the main line (m), Q is system discharge

(m3 sec-1), V is water ow velocity (V ≤ 2 m sec-1) and p is 227

or 3.14.

Fig. 2. Window for pivot lateral diameter and system discharge for Ras

Elwadi farm.

Application rateThe calculation of maximum application rate and application time for

specic sprinkler was major functions of this window. The calculation

procedure used was suggested by Al-Ghobari (2004) as follows:



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Where: AR is the average application rate over width W (mm min -1 for ETc

in mm day-1), k is 60, Q is system discharge, Re is the fraction of applied

water that reaches the soil surface, Oe is the fraction of water that does not

leak from the system pipes, R is effective radius (m), Ram is the maximum

application rate, Tw is application time (min), Dw is sprinkler wetted diameter

at the distance (r) from the pivot (m) and Trev is revolution time (min).

Sprinklers (nozzles) conguration

This window (Fig. 3) represents types of sprinklers (nozzles) and rain guns

used for center pivot systems and their hydraulic characteristics to help the

designer in selecting proper sprinklers. The sprinklers (nozzles) conguration

and selection followed the approaches proposed by King and Kincaid (1997).

Fig. 3. User interface for sprinklers selection.



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Hydraulic characteristics and hardware specications

Simulation of hydraulic system includes determination of friction losses

on the sprinkler line, determination of operating head (pressure) in the

pivot point, distribution of operating pressure along the lateral, sprinklers(nozzles) operating pressure and nozzle size and color (Fig. 4). The hydraulic

characteristics design followed the approaches proposed by Keller and Bliesner

(1990) and Merkley and Allen (2007) as the following equation:

Where: Hf is the friction losses (m), K is 16.42(10)4, F is 0.555 for a center

pivot with a “large” number of outlets and no end gun, Q is the ow rate (L

s-1), C is a roughness coefcient, d is the pipe inside diameter (cm) and R is the

pipe length (m). The determination of sprinklers (nozzles) operating pressure,

nozzle size and discharge was carried out using the following equations as

suggested by Al-Ghobari (2004):

Where: Psp is sprinkler operating pressure (kPa), Pf is friction losses on the

pivot lateral (kPa), r is nozzle spacing from the pivot point (m), R is sprinkler

line length (m), Pe is pressure required in the end of the sprinkler line (kPa),

dsp is nozzle diameter (mm), Qsp is nozzle discharge (L s-1), Ss is sprinklers

spacing (m), Q is system discharge (L s-1) and K is a unit conversion of 10000

in metric units of L s-1

, m, and L s-1

ha-1

.



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System report

This window is for assembly of output data for the system design, which

consists of three reports (Figs. 5a, 5b and Table 1).

Data collection and analysisThe climate data from Atbara meteorological station included rainfall data,

mean maximum and mean minimum temperatures, mean relative humidity,

mean sunshine, wind speed and evaporation. Monthly means for 30 years

(1971 – 2000) were presented in Table 2.

* Dark color

Fig. 4. User interface for hydraulics and hardware specications along the

sprinkler line.



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Soil physical properties for the two sites were obtained from samples

analyzed in Hudeiba Research Station laboratory. The soil in both sites

was classied as sandy clay loam. Using the method proposed by Saxton

et al

. (2006), soil moisture contents at eld capacity and permanent wilting point were determined as 30.6 and 19.6, respectively. Eight sprinklers were

randomly selected along the sprinkler line to measure the sprinkler discharge

and pressure as recommended by Code of Practice for Irrigation Evaluation

(2006).

Results and Discussion

The simulation model CPM was used to determine the center pivot system

design criteria. Table (3) shows the results of irrigated area, readily available

water, reference evapotranspiration, crop evapotranspiration, irrigation intervaland application depth. For Ras Elwadi farm, they were 43.7 ha, 11.9 ha, 49 mm,

8.11 mm day-1, 8.9 mm day-1, 6 days and 70 mm, respectively. While for the

Jordanian Bashair project, they were 55.4 ha, 15.1 ha, 49 mm, 8.11 mm day-1,

9.3 mm day-1, 6 days and 70 mm, respectively. Reference evapotranspiration

was determined using the modied (FAO) Penman-Monteith equation, then

the parameters of crop evapotranspiration, irrigation interval and application

depth were calculated and exhibited in Fig. 1.

Center pivot sprinkler irrigation modelCPM version 1.0.0

System design report

Project data:

Project No.1 :. Project Name: Ras Elwadi farm.

Engineer (Designer): Mamoon.

Project location:

Country: Sudan. Latitude: 17°40

Longitude: 33° 58 Altitude: 346.5 m.

Field Information and water supply:Total eld area: 55.56 ha. Irrigated area: 43.7 ha.

None irrigated area: 11.86 ha.

Maximum available water from source: Well is ________ m3/day.

Soil:

Soil Type: Silty loam soil. Readily available water: 49 mm.

Crop/s Water requirements with application efciency of 70%.

Fig. 5a. System report of project data.



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System discharge:

System type:Without rain gun.

System discharge: 318.6 m3/hr.

Rain gun discharge:_____ m3/hr (if existent).

Main line design:

Main line length: 372.7 m. Main line (Pipe) diameter. Manufacturing:

162.05 mm.

Spans (Towers) No.: 9. Spans (Towers) Spacing: 38 m.

Over hang length: 30.7 m. Rain gun wetted Radius: m.

(if existent).

Application rate:

System application rate: 102.8 mm/hr.

Maximum application rate: 130.8 mm/hr.Sprinklers selection:

Sprinkler (Nozzle) type: Low drift and multiple spray head.

Sprinklers spacings:1.9 m.

Fig. 5b. System report of system discharge.



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T a b l e 1 . S y s t e m r e p o r t ( s a m p l e ) f o r h y d r a u l i c s c h a r a c t e r i s t i c s a n d h a r d w a r e s p e c i

c a t i o n s a l o n g t h e s p r i n k l e r l i n e .

N

o z z .

N

o .

S p a c i n g

f r o m

p r e v i o u s

( m )

D i s t a n c e

f r o m

p i v o t

p o i n t

( m )

S p r i n k l e r

d i s c h a r g e

( L / s )

S p r i n k l e r

d i s c h a r g e

( g p m ) +

S p r i n k

l e r

o p e r a t i n g

p r e s s u

r e

( p s i )

S p r i n k l e r

o p e r a t i n g

p r e s s u r e

( k p a )

N o z z l e

d i a m e t e r

( m m )

N

o z z l e

d

i a m e t e r

(

T H 6

4

i

n c h )

N o z z l e s i z e a n d

c o l o r

I r r i g a t e d

a r e a

( h a )

1

4 6 . 8

4 6 . 8

2 . 7

9 3

4 4 . 2 7 5

3 8 . 2

2 6 3 . 4

1 2 . 6

3

1 . 7

3 2 Y e l l o w

1 . 3

7 7

2

2 . 8

4 9 . 6

0 . 1

7 7

2 . 8 0 6

3 8 . 1

2 6 2 . 4

3 . 2

8

. 1

8 . 5 L a v e n d e r *

0 . 0

8 7

3

2 . 8

5 2 . 4

0 . 1

8 7

2 . 9 6 4

3 7 . 9

2 6 1 . 4

3 . 3

8

. 3

8 . 5 L a v e n d e r *

0 . 0

9 2

4

2 . 8

5 5 . 2

0 . 1

9 7

3 . 1

2 3

3 7 . 8

2 6 0 . 4

3 . 4

8

. 6

9 G r a y

0 . 0

9 7

5

2 . 8

5 8 . 0

0 . 2

0 7

3 . 2

8 1

3 7 . 6

2 5 9 . 4

3 . 5

8

. 8

9 G r a y

0 . 1

0 2

6

2 . 8

6 0 . 8

0 . 2

1 7

3 . 4 4 0

3 7 . 5

2 5 8 . 5

3 . 5

8

. 8

9 G r a y

0 . 1

0 7

7

2 . 8

6 3 . 6

0 . 2

2 7

3 . 5

9 8

3 7 . 3

2 5 7 . 5

3 . 6

9

. 1

9 . 5 G r a y *

0 . 1

1 2

8

2 . 8

6 6 . 4

0 . 2

3 7

3 . 7

5 7

3 7 . 2

2 5 6 . 5

3 . 7

9

. 3

9 . 5 G r a y *

0 . 1

1 7

9

2 . 8

6 9 . 2

0 . 2 4 7

3 . 9

1 5

3 7 . 1

2 5 5 . 5

3 . 8

9

. 6

1 0 T u r q u o i s e

0 . 1

2 2

1

0

2 . 8

7 2 . 0

0 . 2

5 7

4 . 0 7 4

3 6 . 9

2 5 4 . 6

3 . 9

9

. 8


0 . 1

2 7

1

1

2 . 8

7 4 . 8

0 . 2 6 7

4 . 2 3 2

3 6 . 8

2 5 3 . 6

3 . 9

9

. 8


0 . 1

3 2

1

2

2 . 8

7 7 . 6

0 . 2

7 7

4 . 3 9 1

3 6 . 6

2 5 2 . 7

4 . 0

1

0 . 1

1 0 . 5 T u r q u o i s e *

0 . 1

3 7

*

D a r k c o l o r . + : G a l l o n s p e r m i n u t e .



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T a b l e 2 . C l i m a t o l o g i c a l n or m a l s 1 9 7 1 –2 0 0 0 ,A t b ar a S t a t i o n ,L a t .1 7 ° 4 0 / N ,L o n g . 3 3 ° 5

8 / E ,A l t . 3 4 5 m .

M on .

Ai r t e m p e r a t ur e i nº C

M e a n

d r y

t e m p .

Br i gh t

s un s h i n e

d ur a t i on

R e l a t i v e

h umi d i t y

%

R a i nf a l l i nm

m

E VAP .

pi t c h

mm

Wi n d

m e a n

s p e e d

a t 2 m

M .P .D

M a xi m um

Mi ni m um

N o . of r a i n d a y s

M e a n

H S T *

M e a n

L S

T *

º C

Hr s .

%

M e

a n

> = 0 .1

> =1 . 0

> =1 0 . 0

J a n .

2 9 . 8

3 9 .1

1 4 .2

6 . 3

2 2 . 0

9 . 9

8 8

3 6

0 . 0

0 . 0

0 . 0

0 . 0

1 3 . 5

4 . 9 7

F e b .

3 1 . 8

4 1 .4

1 5 .1

5 . 5

2 3 .4

1 0 . 3

9 0

3 1

0 . 0

0 . 0

0 . 0

0 . 0

1 5 . 0

4 . 9 7

M a r c h

3 5 . 7

4 5 . 7

1 8 .4

1 0 . 8

2 7 . 0

1 0 .1

8 4

2 4

0 . 0

0 . 0

0 . 0

0 . 0

1 8 .1

4 . 9 7

A pr .

4 0 . 0

4 6 . 3

2 2 .1

1 5 . 0

3 1 .1

1 0 . 6

8 5

2 3

0 .4

0 .2

0 .1

0 . 0

2 0 .1

4 .2 6

M a y

4 2 . 6

4 7 . 5

2 6 . 5

1 8 . 9

3 4 . 5

9 . 8

7 5

2 3

3 .2

0 . 7

0 . 5

0 .1

2 0 .4

3 . 5 5

J un .

4 3 .2

4 8 . 0

2 8 . 0

2 1 . 6

3 5 . 6

8 . 6

6 5

2 2

1 . 0

0 . 3

0 .2

0 . 0

2 0 . 7

3 . 5 5

J ul .

4 1 .2

4 7 . 7

2 7 . 3

1 9 . 5

3 4 . 3

8 . 7

6 5

3 2

1 5 .1

1 .4

1 . 3

0 .4

1 9 . 0

4 .2 6

A u g .

4 0 . 6

4 6 . 5

2 6 . 9

1 9 . 5

3 3 . 8

8 . 6

6 7

3 7

2 6 . 5

2 .2

2 . 0

0 . 9

1 8 . 0

4 .2 6

S e p .

4 1 . 6

4 7 . 6

2 7 .4

2 0 . 0

3 4 . 5

8 . 6

7 1

3 2

8 . 6

1 .1

1 . 0

0 . 3

1 8 . 5

4 .2 6

O c t .

3 9 . 7

4 4 . 5

2 5 .2

1 6 . 0

3 2 . 5

9 . 8

8 3

3 1

3 . 0

0 . 5

0 . 5

0 .1

1 7 .4

3 . 5 5

N o v .

3 4 . 9

4 0 . 7

2 0 .1

1 1 . 7

2 7 . 5

1 0 .2

9 0

3 6

0 . 0

0 . 0

0 . 0

0 . 0

1 4 . 7

4 .2 6

D e c .

3 1 .1

3 8 . 5

1 6 . 0

6 . 5

2 3 . 6

9 . 7

8 8

4 0

0 . 0

0 . 0

0 . 0

0 . 0

1 3 .2

4 .2 6

Y e a r

3 7 . 7

4 8 . 0

2 2 . 3

5 . 5

3 0 . 0

9 . 6

7 9

3 1

5 7 . 7

6 . 7

5 .4

1 . 8

1 7 .4

-

S o ur c e : S u d a

nM e t r o l o g i c a l A u t h or i t y ,A t b ar a S t a t i o n .

* : H S T : H i g h e s t s t a t i o n t e m p er a t ur e .

* : L S T : L o w e s t s t a t i o n t e m p er a t ur e .



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Table 3 shows sample calculations as CPM Model output. Regarding the

hydraulic characteristics and hardware specications, it was found that the

center pivot system discharges were 318.8 m3 hr -1 and 227.2 m3 hr -1 for Ras

Elwadi farm and the Jordanian Bashair project, respectively (Fig. 2). Onthe other hand, the packages of Low-drift nozzles (LDN) were 116 nozzles

with 2.8 m spacing and 214 nozzles with 1.9 m spacing for Ras Elwadi farm

and the Jordanian Bashair project, respectively. Tables (4 and 5) exhibit the

ratio of actual (measured) to calculated nozzle locations along the sprinkler

line, nozzle discharge, nozzle pressure and nozzle size and color through the

sprinkler line. The columns titled VND and VNP in aforementioned tables

represent the ratio of actual to calculated nozzle discharge and nozzle pressure,

respectively. VND and VNP for Ras Elwadi farm were within the range of

0.82 to 1.13 and 0.97 to 1.17, respectively. For the Jordanian Bashair project

VND and VNP were between 0.84 to 1.90 and 1.03 to 1.23, respectively. The

obtained results indicated that the variation in nozzle discharge were within

11% and 19% and the variation in nozzle pressure was within 11% and 12%

for Ras Elwadi farm and the Jordanian Bashair project, respectively. These

variations may be attributed to the systems performance which was directly

inuenced by inadequate nozzle pressure; nozzles wear and water leakage

through spans connections.



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Table 3. Sample calculations of the design criteria, for the tow center pivot

sprinkler systems.

Design criteria Ras Elwadi farm Jordanian Bashair project

Irrigated areaTotal eld (A) = R 2

A=3.14Í(745.4/2)2/10000 =

43.7 ha

Total eld (A) = R 2

A = 3.14Í(840/2)2/10000

= 55.4 ha

Readily available

water

Equations (1 and 2)

(Total available water )

Taw = (30.6 –

19.6)/100Í1.49Í60Í10 =

98 mm

(Readily available water) Dn =

98Í

0.5 = 49 mm

(Total available

water) Taw = (30.6 –

19.6)/100Í1.49Í60Í10

= 98 mm

(Readily available water)

Dn = 98Í

0.5 = 49 mm

Reference

evapotranspiration

Equation (3)

ETo = 8.11 mm day-1 ETo = 8.11 mm day-1

Crop water

requirements

Equation (5)

For Kc = 1.1

ETcrop (Alfalfa) = 8.11Í1.1=

8.9 mm day-1

For Kc = 1.15

ETcrop (Onion) =

8.11Í1.15= 9.3mm day-1

Irrigation interval

Equation (6)

II = 49/8.9 = 5.5 ≈ 6 days II = 49/9.3 = 5.3 ≈ 6 days

Application depth

Equation (7)

Dg = 49/0.7 = 70 mm

Dg is gross water depth.

Dg = 49/0.7 = 70 mm

Dg is gross water depth.

System discharge

(Q)

Equations (12 and 13)

Q = 43.7Í

70Í

10/115.2 =265.5 m3 hr-1

Q adjusted to selected

diameter, velocity method

162.05Í3600Í(3.14Í1.52

)0.5/4/1000 = 318.8 m3 hr-1 =

1403.6 gpm

Q = 55.4Í

70Í

10/115.2 =336.6 m3 hr-1

Q adjusted to selected

diameter, velocity method

162.05Í3600Í(3.14Í1

.52)0.5/4/1000 = 227.2 m3

hr-1 = 1000.3 gpm



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119

T a b l e 4 . H y d r a u l i c s c h a r a

c t e r i s t i c s a n d h a r d w a r e

s p e c i c a t i o n s - a c t u a l

a n d c a l c u l a t e d a s C P M

o u t p u t

f o r R a s E l w a d i f a r m .

N

N P L

N N S

D F P P

( m )

A N D

( L / s )

C N D

( L / s )

V N D

%

N P A

K p a

( P s

i )

N P C

K p a

( P s i )

V N P

%

A N S C

( 6 4 T h i n c h )

a n d c o l o r

C N S

C

( 6 4 T

h i n c h )

a n d c o l o r

2

0

4

1 0 0 . 4

0 . 3 2

4

0 . 3

5 8

0 . 9

1

2 6 1

. 8

( 3 8

)

2 4 5 . 2

( 3 5 . 6 )

1 . 0 7

1 1 Y e l l o w

1 2 R

e d

3

6

4

1 4 5 . 6

0 . 4 2

4

0 . 5

2

0 . 8

2

2 6 1

. 8

( 3 8

)

2 3 2 . 3

( 3 3 . 7

)

1 . 1 3

1 2 . 5 R e d *

1 4 . 5

B l u e *

5

1

3

1 8 8

0 . 5 9

4

0 . 6 7 1

0 . 8

9

2 6 1

. 8

( 3 8

)

2 2 3 . 3

( 3 2 . 4 )

1 . 1 7

1 5 . 5 D B r o u n *

1 6 . 5

O r a n g e *

6

7

3

2 3 8 . 8

0 . 7 9

2

0 . 8

3 3

0 . 9

5

2 4 8 ( 3 6

)

2 1 8 . 2

( 3 1 . 6 )

1 . 1 4

1 7 D

G r e e n

1 8 . 5

P u r p l e *

8

4

4

2 8 1 . 2

0 . 9 1

3

1 . 0 0 4

0 . 9

1

2 3 4

. 3

( 3 4

)

2 1 9 . 6

( 3 1 . 8

)

1 . 0 7

1 9 B l a c k

2 0 T u r q

1

0 2

4

3 3 2

1 . 1 8

8

1 . 1

8 5

1 . 0

0

2 3 4

. 3

( 3 4

)

2 3 0 . 9

( 3 3 . 5

)

1 . 0 1

2 2 M a r o o n

2 1 . 5

M u s t a r d *

1

1 1

1 3

3 5 7 . 2

1 . 3 1

9

1 . 2

7 5

1 . 0

3

2 3 4

. 3

( 3 4

)

2 4 1 . 2

( 3 5 )

0 . 9 7

2 3 . 5 C r e a m *

2 2 M

a r o o n

1

1 5

1 7

3 6 8 . 4

1 . 4 8

4

1 . 3

1 5

1 . 1

3

2 3 4

. 3

( 3 4

)

2 4 1 . 2

( 3 5 . 8

)

0 . 9 8

2 5 Y e l l o w

2 2 . 5

M a r o o n *

N N

P L : N o z z l e n u m b e r o n p i v o t l a t e r a l .

N N S : N o z z l e n u m b e r o n s p a n .

D F P P : D i s t a n c e f r o m p i v o t p o i n t .

A N

D : A c t u a l n o z z l e d i s c h a r g e .

C N D : C a l c u l a t e d n o z z l e d i s c h a r

g e .

V N D : V a r i a n c e i n n o z z l e d

i s c h a r g e , r a t i o o f a c t u a l t o c a l c u l a t e d ( % ) .

N P A : N o z z l e p r e s s u r e a c t u a l .

N P C : N o z z l e p r e s s u r e c a l c u l a t e d .

V N P : V a r i a n c e i n n o z z l e p r

e s s u r e , r a t i o o f a c t u a l t o c a l c u l a t e d ( %

) .

A N

S C : A c t u a l n o z z l e s i z e ( 6 4 T h i n c h ) a

n d c o l o r .

C N

S C : C a l c u l a t e d n o z z l e s i z e ( 6 4 T h i n c h ) a n d c o l o r .



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120

T a b l e 5 .

H y d r a u l i c s c h ar a c t e r i s t i c s

a n d h ar d w ar e s p e c i c a t i o

n s - a c t u a l a n d c a l c u l a t e d

a s C P M o u t p u t f or J or d a n i a n

B a s h

a i r pr o j e c t .

N NP L

N N S

DF P P

( m )

A ND

( L / s )

C ND

( L / s )

V ND

%

NP AK p a

( P s i )

NP C

K p a

( P s i )

V NP

%

A N S C

( 6 4 T h i n c h )

a n d c ol or

C N S C

( 6 4 T h i n c h )

a n d c ol or

2 2

2

4 5 . 7

0 . 0 8 2

0 . 0 6 2

1 . 3 2

1 3 1 . 0 0 5

( 1 9 )

1 0 6 . 9

( 1 5 . 5 )

1 .2 3

6 . 5 Y e l l o w

1 2 R e d

3 8

1 8

7 6 .1

0 .1 2 0

0 .1 0 3

1 .1 7

1 1 7 .2 1 5

( 1 7 )

1 0 6 . 9

( 1 5 . 5 )

1 .1 0

8 L a v e n d e r

1 4 . 5 Bl u e *

6 2

2 0

1 2 2 . 7

0 .1 8 8

0 .1 6 7

1 .1 3

1 1 7 .2 1 5

( 1 7 )

1 0 6 . 9

( 1 5 . 5 )

1 .1 0

1 0 T ur q u oi s e

1 6 . 5 Or a n g e *

8 4

2 0

1 6 5 . 5

0 .2 2 8

0 .2 2 5

1 . 0 1

1 1 7 .2 1 5

( 1 7 )

1 0 6 . 9

( 1 5 . 5 )

1 .1 0

1 1 Y e l l o w

1 8 . 5 P ur pl e *

1 2 0

6

2 3 6 . 6

0 .2 8 5

0 . 3 2 2

0 . 8 9

1 1 0 . 3 2 ( 1 6 )

1 0 6 . 9

( 1 5 . 5 )

1 . 0 3

1 2 . 5 R e d *

2 0 T ur q

1 4 5

6

2 8 5 . 3

0 . 3 2 7

0 . 3 8 8

0 . 8 4

1 1 0 . 3 2 ( 1 6 )

1 0 6 . 9

( 1 5 . 5 )

1 . 0 3

1 3 . 5 Wh i t e *

2 1 . 5 M u s t a r d

*

1 6 3

2 4

3 1 9 . 5

0 .4 0 0

0 .4 3 4

0 . 9 2

1 2 4 .1 1

( 1 8 )

1 0 6 . 9

( 1 5 . 5 )

1 .1 6

1 4 . 5 Bl u e *

2 2 M a r o on

2 1 3

2 4

4 1 7 .1

1 . 0 8 0

0 . 5 6 7

1 . 9 0

1 2 4 .1 1 ( 1 8 )

1 0 6 . 9

( 1 5 . 5 )

1 .1 6

1 8 P ur pl e

2 2 . 5 M a r o on*

N NP L : N ozz

l e n um b e r on pi v o t l a t e r a l .

N N S : N ozzl e n um b e r on s p a n .

DF P P : Di s t a n c e f r om pi v o t p oi n t .

A ND : A c t u a l n ozzl e d i s c h a r g e .

C ND : C a l c ul a t e d n ozzl e d i s c h a r g e .

V ND : V a r i a n c e i nn ozzl e d i s c h a r g e ,r a t i o of a c t u a l t o c a l c ul a t e d ( % ) .

NP A : N ozzl e

pr e s s ur e a c t u a l .

NP C

: N ozzl e pr e s s ur e c a l c ul a t e d .

V NP : V a r i a n c e i nn ozzl e pr e s s ur e ,r a t i o of a c t u a l t o c a l c ul a t e d ( % ) .

A N S C : A c t u a l n ozzl e s i z e ( 6 4 T h i n c h ) a n d c ol or .

C N S C : C a l c u

l a t e d n ozzl e s i z e ( 6 4 T h i n c h ) a n d c ol or .



19/20

121

Conclusion

The Center Pivot Model (CPM), which is a computer technology, could1-

successfully be used to assess appropriate center pivot system design

and performance.

The execution of the simulated system using the viable alternatives2-

will help the engineers and practitioners to understand the operational

mechanism of the center pivot system and taking appropriate measures

for improvement.

References

Abreu, V. M. and Pereira, L. S. (2002). Sprinkler irrigation systems design

using ISADim. In: 2002 ASAE Annual International Meeting/CIGR

XVth World Congress Chicago, ASAE and CIGR, Paper 022254.

Allen, R. G., Pereira, L. S., Raes, D. and Smith, M. (1998). Crop

evapotranspiration, guidelines for computing crop water requirements.

FAO Irrig. and Drain. Paper 56, Food and Agric. Orgn. of the United

Nations, Rome, Italy. 300 Pp.

Al-Ghobari, M. H. (2004) Sprinkler Irrigation Systems. Textbook, College of

Food and Agricultural Sciences, King Saud University, Saudi Arabia,

Riyadh.

Andrade, C. L. T. and Allen R. G. (1997). SPRINKMOD - Sprinkler Simulation

Model User’s Manual. Utah State University (USA) and EMBRAPA

(Brazil). Available at: www.usu.com.

Code of Practice for Irrigation Evaluation (2006). Page Bloomer Associates

Ltd. New Zeland.

Evans, R. G., Barker, J. C., Smith J. T. and Shefeld, R. E. (1997). Center

Pivot and Linear Move, North Carolina Cooperative, Extension

Service, North Carolina State University, E97-30398.

Evans, R. G. (2001). Center Pivot Irrigation. Washington State University.

www.bsyse. prosser .wsu.edu/report/centerpivot. pdf .Heermann, D. F. and Kohl, R. A. (1983). Fluid dynamics of sprinkler systems.

Chapter 14. In: Design and Operation of Farm Irrigation Systems,

ASAE Monograph No. 3, Pp. 583-618.

Jensen, M. E. (1980). Design and operation of farm irrigation systems. ASAE,

Beltsville.

Jorge, J. and Pereira, L. S. (2003). Simulation and evaluation of set sprinkler

systems with AVASPER. In: Proceeding of improved irrigation

technologies and methods: Research, development and testing. ICID

International workshop, Montpellier, France.



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Keller, J. and Bliesner, R. D. (1990). Sprinkle and Trickle Irrigation. van

Nostrand Reinhold. New York. Pp. 99-115.

King, B. A. and Kincaid, D. C. (1997). Optimal performance from center

pivot sprinkler systems. College of Agriculture, University of Idaho.BUL 797.

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Merkley G. P. and Allen, R. G. (2007). Sprinkler and Trickle Irrigation. Utah

State University. Dept. of Bio. And irrig. Eng. Lecture Notes.

Merriam, J. L. and Keller, J. (1978). Farm irrigation system evaluation: A

guide for management. Utah State Univ. Agricultural and Irrigation

Engineering Department. Logan.

Saxton, K. E., Willey P. H. and Rawls W. J. (2006). Field and pond Hydrologic

Analysis with the SPAW Model. ASAE Annual International Meeting,

Portland, Oregon 9 - 12 July, 2006.

Withers, B. and Vipond, S. (1985). Irrigation design and practice. Batsford

Academic and Educational Limited, London. P. 148-155.


Documents

A Software Tool for Appropriate Design of Center Pivot Irrigation