Hydraulic and Economic Evaluation of a Center Pivot Irrigation System in West Omdurman District, Sudan

Zechariah Jeremaiho Othong Loung

B.Sc. (Honor) in Agricultural Science (Agricultural Engineering)

University of Khartoum

September, 2013

A Dissertation

Submitted to the University of Gezira in Partial Fulfillment of the Requirements for the Award of the Degree of Master of Science

Agricultural Engineering (Irrigation Engineering)

Department of Agricultural Engineering

Faculty of Agricultural Sciences

August, 2016

Hydraulic and Economic Evaluation of a Center Pivot Irrigation System in West Omdurman District, Sudan

Zechariah Jeremaiho Othong Loung

Supervision Committee Signature

Main Supervisor: Dr. Muna Mohamed Elhag Musa ….…………......

Co- Supervisor: Dr. Elsadig Ahmed Elfaki Abdalla ………………………

Date: August, 2016

Hydraulic and Economic Evaluation of a Center Pivot Irrigation System in West Omdurman District, Sudan

Zechariah Jeremaiho Othong Loung

Examination Committee:

Name Position Signature

Dr. Muna Mohamed Elhag Musa Chairperson………......

Dr. Bashir Mohammed Ahmed External Examiner.……………...

Dr. Sami Ibrahim M. N. Gabir Internal Examiner ……………….

Date of Examination: 15, August, 2016

Dedication To:

Soul of my father who taught me the

Meaning of life.

My mother, brothers and sisters.

My friends and all who encouraged me to

Carry out this research work,

May God bless them…

Acknowledgment Praise is to God who gave me health; I would like to express my sincere gratitude and thanks to my main supervisor Dr.Muna Mohamed Elhag for her guidance, and encouragement and help to carry out this work. Greater thanks are due to Dr. Elsadig Ahmed Elfaki my co- supervisor of his guidance.

Sincere thanks are due to Mr. Hisham Musa and Mr. Khidir Suliman for their highly appreciated help and advice.

My sincere thanks are also due to Mohamed El-sheik for his kindly permission to carry out evaluation of a center pivot irrigation system in his farm, west Omdurman area, Sudan.

My sincere thanks are also due to Mashair Ibrahim, ministry of Agriculture, Khartoum State -Sudan, for her kindly permission to carry out this work.

Hydraulic and Economic Evaluation of a Center Pivot Irrigation System in West Omdurman District, Sudan

Zechariah Jeremaiho Othong Loung

Abstract Sprinkler irrigation is one of the modern techniques of irrigation and now has been introduced to limited areas in the Sudan. The objective of this study was to evaluate the hydraulic and economic performance of a center pivot irrigation system. This study was carried out in Wad El-sheik Agricultural Scheme which produces alfalfa and potatoes in west Omdurman. The performance of the system was evaluated at a rotational speed of 20 hours per day, to measure the water depth and nozzle discharge. Samples were taken using 48 catch cans, measuring cylinders (100 ml and 500 ml). Measurement was conducted on coefficient uniformity (퐶푢%) which was found to be 71.8% and was considered low when compared to the recommended value of 85%. The distribution uniformity (퐷푢%) gave the value of 63.5%, application efficiency (퐸푎%) gave the value of 77.1%, irrigation efficiency (E %) was found to be 48.6% and scheduling coefficient (푆푐%) gave the value of 1.5%. These values are satisfactory compared with international standards. The rate of water loss was 38.1%. The economic evaluation of a center pivot irrigation system covering 38 ha showed that ownership and operating costs were 331 110 US$ per year; and, yearly depreciation was 19 664 US$. The yearly income of the system was 385 848 US$. The study indicated that the yearly net present value was 54 738 US$. To obtain high hydraulic efficiencies and low water losses, it is recommended that the system must change the sprayers and operate them at the recommended pressure. Also, taxes and labors costs must be included in the economic evaluation.

التقييم الهيدروليكي واالقتصادي لنظام الري المحوري،حالة دراسة في غرب أمدرمان ,السودان

زكريا جرمايوأوضونق لونق

مخلص الدراسة الري بالرش هو أحد التقنيات الحديثة في الري، ويستخدم في مناطق محدودة في السودان. الهدف األساسي من هذه الدراسة هو تقييم األداء الهيدروليكي واإلقتصادي لنظام الري المحوري، بمشروع ود الشيخ الزراعي إلنتاج أعالف البرسيم و تقاوي البطاطس. تم تقييم األداء الهيدروليكي للنظام الذي يعمل بمعدل سرعة تدويرية 20 ساعة في اليوم، بقياس عمق المياه وتدفق الرشاش. تم استخدم 48 علبة للتجميع المياه, إسطوانة قياس )100 مل و 500 مل( باالضافة الي بيانات المحصول. أوضحت النتائج

أن قيمة معامل التوزيع )%퐶푢( يساوي 71.8% والتي تعتبر منخفضة إذا قورنت بالقيمة الموصي بها

عالميا 85%, إتساقالتوزيع (%퐷푢) أعطي هذا النظام قيمة 63.5% وكفاءة التطبيق (%퐸푎) كانت

قيمتها 77.1% وبينما كانت كفاءة الري )E( تساوي 48.6% و معامل الجدولة (%푆푐) أعطي قيمة 1.5% وتعتبر هذه القيم مناسبه. ونسبة الفاقد في كمية المياه كانت 38.1%.التقييم اإلقتصادي لنظام الري المحوري والذي يغطي مساحة 38 هكتار أوضح أن تكاليف الملكية والتشغيل بقيمة 331110 دوالر أمريكي في السنة. كذلك وجدت إن قيمة اإلهال ك السنوي للنظام عبارة عن 19664 دوالر أمريكي.الدخل السنوي للنظام يساوي 385848 دوالر أمريكي، كذلك أشارت الدراسة إلي أن صافي الفائدة الكلية السنوية عبارة عن 54738 دوالر أمريكي؛ أوضحت من خالل هذه الدراسة بأن التقييم اإلقتصادي للنظام مربح تحت ظروف هذه المنطقة بالرغم من تدني كفاءة التشغيل و هدر كميات كبيرة من المياه. للحصول علي كفاءات هيدروليكية عالية وفواقد مائية منخفضة، يوصي بتغيير الرشاشات وتشغيليها تحت الضغط الموصي به. كذلك البد من إدخال تكاليف الضرائب والعمالة األخري في التقييم اإلقتصادي.

List of Contents Page

Dedication …………………………………………………………….. I

Acknowledgement …………………………………………………….. II

English Abstract ………………………………………………………. III Arabic Abstract ………………………………………………………… IV

List of Contents ………………………………………………………… V

List of Tables …………………………………………………………… X

List of Plates ……………………………………………………………. XI List of Appendices ……………………………………………………… XII List of Abbreviations and Notations …………………………………… XIII CHAPTER ONE: INTRODUCTION

1.1 Introduction ……………………………………………………… 1 1.2 Objectives ………………………………………………………… 3 CHAPTER TWO: LITERATURE REVIEW 2.1 Irrigation ………………………………………………………… 4 2.2 Factors Bearing on Irrigation System Selection ………………… 4 2.2.1 Distribution Uniformity ……………………………………….. 4 2.2.2 Wind Speed ……………………………………………………. 4 2.2.3 Robust of Irrigation System ……………………………………. 4 2.2.4 Easy of Operation and Maintenance …………………………… 4 2.2.5 Climate ………………………………………………………….. 5 2.2.6 Soil ……………………………………………………………… 5 2.2.7 Topography ……………………………………………………… 5 2.2.8 Water ……………………………………………………………. 5 2.2.9 Cultivated Crops ………………………………………………… 5 5

2.2.10 Labor……………………………………………………………. 5 2.3 Surface Irrigation …………………………………………………… 6 2.3.1 The Principle of Surface Irrigation Methods: ……………………… 6 1. Basin Irrigation ……………………………………………………… 6 2. Border Irrigation ……………………………………………………. 6 3. Furrow Irrigation …………………………………………………… 6 2.4 Sub-surface Irrigation ………………………………………………. 6 2.5 Drip Irrigation ……………………………………………………… 6 2.6 Sprinkler Irrigation …………………………………………………. 6 2.6.1 Basic Components of Sprinkler System ………………………….. 7 1. Water Source ……………………………………………………. 7 2. Pumping System ………………………………………………… 7 3. Main Line ……………………………………………………….. 7 4. Lateral Pipe Line ………………………………………………... 7 5. Sprinkler Head …………………………………………………... 7 6. Rotating Head …………………………………………………… 7 7. Risers ……………………………………………………………. 7 8. Pipe or Tubing …………………………………………………. 8 9. Pumping and Power System …………………………………… 8 2.6.2 Types of Sprinkler Systems ……………………………………… 8 1. Hand-Move or (Portable) System ………………………………. 8 2. Linear Move System ……………………………………………. 8 3. Side-Roll System ………………………………………………... 8 4. Low Energy Precision Application ……………………………… 8 5. Solid-Set System ……………………………………………….. 9 6. Permanent System ……………………………………………… 9 7. High Pressure Large Volume Sprinkler System ………………… 9 8. Stationary or Fixed Sprinkler system …………………………… 9 9. Perforated Sprinkler system …………………………………… 9 10. Center Pivot Irrigation System ………………………………… 9 2.6.3 Center Pivot System Components……………………………….. 9

1. Water Source …………………………………………………… 9 2. Water Supply System ………………………………………….. 9 3. Towers ………………………………………………………… 10 4. Wheels ………………………………………………………….. 10 5. Lateral Pipe Line ……………………………………………….. 10 6. Sprinklers ……………………………………………………….. 10 7. Riser Pipes ………………………………………………………. 10 8. Drive Units ……………………………………………………… 10 9. Pumping and Power System …………………………………….. 10 10. Filtration Method ……………………………………………….. 10 11. Fertilizer and Pesticides Storage (Fertigation Unit) ……………. 10 2.6.4 Advantages of Center- Pivot Irrigation System…………………... 10 2.6.5Disadvantages of Center Pivot Irrigation System ……………….. 11 2.7Hydraulics principles of Center Pivot Irrigation System: ………… 11 2.7.1 Total Area Irrigated ………………………………………………. 11 2.7.2 Number of Nozzles ……………………………………………….. 12 2.7.3 Area Covered by the First Nozzles ……………………………… 12 2.7.4 Required Discharge of Each Nozzle …………………………….. 12 2.7.5 Discharge of lateral pipe line …………………………………….. 13 2.7.6 Diameter of pipe line …………………………………………….. 13 2.7.7 Diameter of pipe line in (inch) …………………………………… 13 2.7.8 Length of the pipe ………………………………………………... 13 2.7.9 Pressure Head of the last Nozzle………………………………… 14 2.7.10 Total Dynamic Head of the Pump ……………………………… 14 2.7.11 Required Hydro Power of the Pump...... CHAPTER THREE MATERIALS AND METHODS 15 3.1 Study site ……………………………………………………………… 15 3.2 Soil …………………………………………………………………….. 15 3.3 Climate …………………………………………………………………. 15 3.4 Features of the Center Pivot System …………………………………... 15 3.4.1 Water Source ………………………………………...... 15

3.4.2 Power and Pumping Unit ……………………………………………. 16 3.4.3 Flow-Meter ………………………………………………………….. 16 3.4.4 Pivot Center …………………………………………………………… 16 3.4.5 Drive Unit (Towers) …………………………………………………… 16 3.4.6 Mainline pipe………………………………………………………….. 16 3.4.7 Sprinkler System……………………………………………………… 16 3.4.8 Fertigation Unit………………………………………………………. 16 3.4.9 Control Panel…………………………………………………………. 17 3.5 Data Analysis …………………………………………………………… 17 3.5.1 Crop Water Requirement…………………………………………….. 17

3.5.2 Crop Coefficient (퐾푐)………………………………………………….. 17 3.5.3 Soil moisture content………………………………………………….. 19 3.5.4 Sprinkler Coverage (water depth) Measurement ……………………… 20 3.6 Hydraulic Performance…………………………………………………… 21

3.6.1 Coefficient of Uniformity (퐶푢)………………………………………… 21

3.6.2 Uniformity Distribution (퐷푢)…………………………………………… 21

3.6.3 Application Efficiency ( 퐸푎)……………………………………………. 22 3.6.4 Irrigation Efficiency (E) …………………………………………………. 22 22 3.6.5 Scheduling Coefficient (푆푐) ………………………………………………. 3.6.6 Nozzle Discharge …………………………………………………………. 22 3.6.7 Percentage of Water Loss …………………………………………………. 23 3.7 Economic Evaluation of the Center Pivot Irrigation System ………………. 23 3.7.1 Benefit to Cost Analysis………………………………………………….. 23 3.7.2 Cost Analysis………………………………………......

CHAPTER FOUR: RESULTS AND DISCUSSION 24 4.1 Hydraulic Performance Evaluation ………………………………………… 24 4.1.1 Coefficient of Uniformity (퐶푢%) ………………………………………… 24 4.1.2 Distribution Uniformity (퐷푢%) ………………………………………….... 25 4.1.3Application Efficiency ( 퐸푎%) …………………………………………… 26 4.1.4 Irrigation Efficiency ………………………………………………………. 26

4.1.5 Scheduling Coefficient …………………………………………………….

4.1.6 Percentage of Water Losses ………………………………………………. 27

4.2 Crop Evapotranspiration (퐸푇푐) ……………………………………………... 27 4.3 Soil Moisture Content ………………………………………………………. 27 4.4 Available Water …………………………………………………………….. 27

4.5 Economic evaluation for producing fodder crop under Center Pivot ………. 28 4.5.1 Economics of installing a new pivot irrigation system …………………. 28 4.5.2 Crop Yield ……………………………………………………………….. 29 4.5.3 Crop Benefit ……………………………………………………………… 29 4.5.4 Cost Analysis ……………………………………………………………... 29 4.5.5 Benefit to Cost Analysis (BCA) …………………………………………. 29 CHAPTER FIVE: CONCLUSIONS ANDRECOMMENDATIONS 5.1 Conclusions ………………………………………………………………… 31 5.2 Recommendations …………………………………………………………... 31 REFERNCES…………………………………………………………………... 32

APPENDICES…………………………………………………………………. 35

List of Tables

Table Page

4.1 Values of Coefficient of Uniformity (퐶푢%)……….. ………….… 24

4.2 Values of Distribution Uniformity (퐷푢%)…………….……..….. 25

4.3 Values of Application Efficiency (퐸푎%)…………….………….. 25

4.4 Values of Irrigation Efficiency (E %)……..……………………... 26

4.5 Values of Scheduling Coefficient (푆푐%)…………….………….. 26

4.6 Soil Moisture Content Before and After Irrigation ...…..………. 27

4.7 Available Water Before Irrigation……………………..………... 27

4.8 Available Water After Irrigation………………………………… 28

4.9 Components Costs for the Irrigation System …………………… 28

List of Plates

Plate Page

3.1 Experimental Equipment…………………………………………. 18

3.2 Water Source……………………………………………………... 19

3.3 Pumping and Power Unit…………………………………………. 19

3.4 Flow- meter…………………………………………...………….. 19

3.5 Pivot Center…………………………………..………………….. 19

3.6 Drive Unit………………………………..………………………. 19

3.7 Mainline Pipe………………………………..…………………... 20

3.8 Sprinkler System……………………………………………….... 20

3.9 Fertigation Unit………………………………………………….. 20

3.10 Control Panel………………………..…………………………... 20

List of Appendices

Appendix Page

A Climate Data……………………………………………….…….. 35

B Soil Moisture Content……………………………………….…... 37

C Measuring Water Depth…………………………………………. 44

List of Abbreviations

Abbreviation Name

Total area 퐴푡

L The length of lateral pipeline

0.116 Constant

n Number of nozzles

Christiansen’s coefficient uniformity 퐶푢

Ns Spaces between nozzles

Area covered by the first nozzle 퐴𝑖

퐴푛 Area can be covered by each nozzle

푑푤 Depth of water that must be added to crop daily

T Operating time

Ea System efficiency

3600 Constant

푄퐿 Lateral discharge (total discharge)

E Irrigation efficiency

D Diameter of lateral

푇푝 System operating time

퐷𝑖푛푐ℎ Diameter of pipe line

0.0254 Constant

푃ℎ푒푎푑 Pressure Head of the last Nozzle

푃푎 Operating pressure of last nozzle 훾 98102.1320

퐸푝 Total dynamic head of the pump

퐻푠 Static head of the pump

5 ∑ ℎ퐿2 Head losses at the range of Re> 10

5 ∑ ℎ퐿1 Head losses at the range of푅푒 ≤ 10

푍푚 The height or depression of the surface

푃ℎ푦푑푟표 Hydropower of the pump

Y Specific weight of the water which is 9810

H Total dynamic head of the pump 1000 Constant to get the hydropower 0.7 Efficiency of the pump

퐸푇푐 Crop evapotranspiration

퐸푇° Reference evaporations

퐾푐 Crop coefficient MC Soil moisture content

푀푚 Weight of the wet sample

푀푑 Weight of the dry sample

퐶푢 Christiansen‘s coefficient of uniformity Ex Average absolute deviation from the mean application rate N Number of observations M Mean value of observation Du Distribution of uniformity

퐸푎 Application Efficiency Ws The average depth of water caught in the cans

Wf The average depth of application in the system flow meter 푆푐 Scheduling Coefficient BCR Benefit Cost Ratio

퐵푡 Benefit in time t R The discount rate

퐶푡 Cost in time Q Discharge

푞푛 Required discharge Km Kilo meter

푀푑 Weight of the dry sample BD Density VOL Volume

M Meter Ft Foot Hp Horsepower GPM Gallon per minute

Mm Millimeter CROPWAT Crop water G Gram Cm Centimeter Ml Milliliter Vi Individual catch can T Time Ha Hectare US$ United States Dollar T Tone Kg Kilogram BCA Benefit Cost Analysis L/Sec Liter per second 퐶푚3 Centimeter cubic 푣̅ Average volume of application over all catch cans 퐸° East degree 푁° North degree 푚3 Meter cubic 휋 3.14

CHAPTER ONE

INTRODUCTION

1.1 Introduction Irrigation is the artificial application of water to the soil to ensure sufficient moisture for the purpose of crop production. In many areas of the world, the amount and timing of rainfall are not adequate to meet the moisture requirement of crop. Irrigation water is applied to supplement the water available from rainfall and contribution to soil moisture, (Keller, 1976). The major constraints to produce more food to meet the increasing demands of the world population are land and water. One possible approach to conserve these scarce resources may be through improving the performance of the existing irrigation projects, (Keller, 1976).

Sudan is mainly an agricultural country, rich with natural resources that need to be utilized efficiently for self-satisfaction and with excess for export. Water resources in the Sudan are mainly from rain, the River Nile, seasonal streams and underground aquifers, while the River Nile and its tributaries are considered the main conventional source of water for reliable agricultural development. The Sudan is an integral part of the world with more than 1.5 million squaresof land and good water quality. The Northern part which has rainfall less than 300 mm per year depends mainly on the River Nile. Sudan cannot use this water freely because of the bilateral agreement with Egypt in 1959 which determines Sudan’s share at 20.5 billion cubic meters per year as measured at Aswan, (Sabri, 2007).

Internally produced water resources in Sudan are rather limited. The erratic nature of rainfall and its concentration in a short season, places Sudan in a vulnerable situation. Especially in yrain-fed areas 64percent of the Nile Basin lies in Sudan, while 80 percent of Sudanese lies in the Nile Basin. Rainfall is the main source of the non-Nilotic streams, and at Bahr Elgazal Basin. Whereas rainfall over the central Africa plateau (Equatorial lake) andover the Ethiopian- Eritrean highlands is the main source of the River Nile system and other trans boundary seasonal streams (Gash and Baraka), (Elgassim,2006).

Ground water development in the Sudan, and indeed in the whole Nile basin riparian countries, is on increase for both rural and urban domestic supply, particularly in the regions

20 where ground water is only source. The sedimentary Nubian sand stone and Umm Ruwaba formation are the main aquifer in the Sudan; extend at a depth ranging from 40 to 400 meters (Sabri, 2007).

The annual recharge of ground water is difficult to assess accurately, however, the potential has been estimated to be about 4 billion cubic meters, and about 75% of the potential ground water may be utilized for agriculture during coming 5 to 10 years and current uses for both agriculture and domestic uses is about 1.0 billion cubic meters (Eldwa,2003).

The main irrigation method practiced in the Sudan is surface irrigation, where irrigation efficiency is low due to losses by runoff, deep percolation and over irrigation. This low efficiency leads to increase cost of irrigation that coupled with water shortage. Irrigation modernization is accepted as a strategic option to increase water productivity, total production and economic output. This can be achieved by introducing modern irrigation systems namely overhead (sprinkler), drip irrigation systems and center pivot irrigation systems. Drip irrigation is not yet commonly used in crop production in the Sudan; it is used in small private farms. Sudan has vast rain fed areas but they are generally of low productivity mainly because of their dependence upon the amount and distribution of rainfall. Some of these areas can be irrigated using supplementary irrigation as from harvested water to improve their production. Surveyed some areas in the Sudan, which could be adapted to drip irrigation for their soil characteristics and lack of water such areas in Northern state, Northern Kordufan and Darfur it can be used to produce valuable crops (Ahmed, 1991).

The sprinkler irrigation systems especially center pivot and linear move irrigation systems have been introduced in limited areas in the Sudan. Expansion in irrigated agriculture in light soils and marginal lands requires the use of modern irrigation systems with high efficiency such as sprinkler and drip irrigation. Due to low efficiencies of surface irrigation, center – pivot irrigation method introduces recently in the Sudan. The system is selected due to the many advantages it can offer, such as ability to irrigate large areas (40 to 70 hectares) ease of use due to automation low labor requirements and the ability of the system to work in the rough field in addition to the water conservation capability due to water control and high distribution uniformity (pair, 1975).

Furthermore, the system enables the operator to utilize available irrigation scheduling procedures more efficiently which results in an appreciable saving in both water and energy. Uniformity, large amounts of energy are required to develop the pressures necessary for effective operation. However, high pressure systems are required to attain high water application efficiency, which allows for more savings in the amounts of water applied. As a consequence, the energy costs for pumping and hence distributing water through center- pivot irrigation systems are increasing rapidly and will continue so in the future (Amir, 2014).

1.2 Objectives: The main objective of this study is to evaluate the hydraulic and economic performance of center pivot irrigation system in west Omdurman area, Sudan. The Specific objectives of this study are to: 1. Study the effect of the uniformity coefficient on alfalfa 2. Evaluate the distribution uniformity, application efficiency, irrigation efficiency and scheduling coefficient for alfalfa 3. Study the effect of water losses of sprinkler irrigation system on alfalfa 4. Evaluate the economic performance of a center pivot system for producing fodder crops for one season

CHAPTER TWO

LITERATURE REVIEW

2.1 Irrigation Irrigation in generally is defined as the application of water to the soil for the purpose of supplying the moisture essential for plant growth (Pair, 1968). 2.2 Factors Bearing on Irrigation System Selection Selections of irrigation system depend on many factors which include climate, soil, availability of water, labor, crops to be grown, availability of enough fund and the amount of time and effort required before operation (Keller, 1976). 2.2.1 Distribution Uniformity Uniformity distribution is an assessment of an irrigation system’s nozzle package with regard to the spatial distribution of water on the treatment site. Uniformity distribution pertains to the application irrigation water in conjunction with pesticide or fertilizer (Keller, 1976). 2.2.2 Wind Speed Wind speed effects are critical to field sprinkler distribution uniformity. It is always recommended that “Alternate set” lateral placement be used. It’s just that the laterals are offset by a half spacing, placed in alternate locations for irrigation (Keller, 1976). 2.2.3 Robust of Irrigation System This is a pyramidal structure of about 3.5–4.5 m height, built up with galvanized steel angular profiles and anchored on a concrete square platform. This structure has an access ladder. It is the head of the system and carries all equipment necessary for the control of the system, such asthe system water fed up-going piece of pipe with the elbow on the top and inlets for fertilizer injection; the Collector ring, the Central Control Panel (Keller, 1976). 2.2.4 Easy of Operation and Maintenance The speed of the irrigator is controlled by an electronic control system, which allows the operator to set the application rate required and hence the travel speed as output in terms of water flow is usually fixed (Keller, 1976).

2.2.5 Climate The climate is very important factor in any sort of cultivation, whatever the circumstances, it’s important to obtain all possible information about the climate, the most useful data being rainfall, temperature, evaporation, humidity and daily amounts of sun shine hours (Keller, 1976). 2.2.6 Soil Soil factors that contribute to determine the irrigation type are: type of soil, depth, salinity, internal drainage and coefficient of permeability. 2.2.7 Topography Topography means the form and shape of the land. Almost any land however steep, can be irrigated if it can be cultivated, depending upon the method of irrigation and the skill and resources of farmer (Stern, 1987). 2.2.8 Water Water quantity and quality affect selection of irrigation type, and the amount of water needed for irrigation depends not only on climatic condition and the total area to be irrigated, but also on the crop to be grown, and suspended materials which can be found may determine the system of irrigation (Amir, 2014). 2.2.9 Cultivated Crops Surface irrigation can be used for all types of crops. Sprinkler and drip irrigation, because of their high capital investment per area, are mostly used for high value cash crops (Brouwer, 1994). 2.2.10 Labor Surface irrigation often requires a much higher labor input for construction operation, maintenance than sprinkler irrigation and drip irrigation systems (Brouwer, 1994). 2.3Surface Irrigation Surface irrigation systems are those which supply water to the land at ground surface level. They are also sometime known as gravity system, because the water flows under the action of gravity, and without the use of pumps. Water is supplied directly to soil surface from channels and located at upper reach of field (Michael, 1983).

2.3.1 The Principle of Surface Irrigation Methods: 4. Basin Irrigation The method involves dividing a field into small units. The basins are filled with water within about 10 cm of the top the level, and the water is retained until it infiltrates into the soil (Stern, 1987). 5. Border Irrigation A field is divided by border (low banks) into series of strips, which may be from 3 to 30m wide and from 100 to 800m long, with an even moderate slope along their length (Stern, 1987). 6. Furrow Irrigation Furrows are small channels formed in the soil. Infiltration occurs laterally and vertically through the wetted perimeter of the furrow. The uniformity is highly, dependent on proper management (Zoldoske and Solomon, 1988). 2.4 Sub-surface Irrigation This method is practiced widely on a small scale, wherever there is low lying alluvial land adjacent to river or stream. And where the land and river bed are sufficiently permeable for water to be maintained in the ground at a suitable depth for plant growth (Stern, 1987). 2.5 Drip Irrigation The application of water to the soil at very low rate (2 to 10 liters per hour per area) through small outlets (trickle or emitters), water is supplied to the trickle through polythene pipes (12 to 16 mm diameter). The water is supplied under pressure (1 to 3 atmospheres) (Stern, 1987). 2.6 Sprinkler Irrigation In this method of irrigation water is sprayed into air, and allowed to fall on the ground surface somewhat resembling rainfall (Michael, 1983). Sprinkler irrigation can be used for almost all crops (except rice and jutes) and on most soils types. 2.6.1 Basic Components of Sprinkler System The sprinkler irrigation system is generally consisting of:

10. Water Source It can be a river or a channel or a well, but a good clean supply of water, free of suspended material is required to avoid problems of sprinkler nozzles blockage (Keller, 1976). 11. Pumping System The pump usually lifts water from the source and pushes it through the distribution system and sprinklers (Michael, 1983). 12. Main Line Main lines may be permanent or portable, permanent mains are used at farms where field boundaries are fixed and where crops require full season irrigation (Michael, 1983). 13. Lateral Pipe Line The lateral lines are the main pipe at center pivot system. It used to carry out and distributed the water into a number of Nozzles. Lateral lines are usually portable. Buried permanent laterals are, however, used for some orchards trees. Quick coupled aluminum pipe is best for most portable laterals (James, 1975). 14. Sprinkler Head The sprinkler head is the most important component of sprinkler irrigation. It is used to spray the water over ground (James, 1975).

15. Rotating Head These have three types, rapidly whirling sprinkler, a boom type sprinkler and the slowly rotating impact driven sprinkler head (James, 1975). 16. Risers Riser pipe connects the rotating or fixed sprinkler head to the sprinkler lateral (James, 1975). 17. Pipe or Tubing Pipe or tube are used in sprinkler system, and made from steel, asbestos. Cement or plastic, it ranges from 2 to 10 inches or more in diameter (James, 1975).

18. Pumping and Power System Sprinkler irrigation pumps are powered by electric motors or internal combustion engines (James, 1975). 2.6.2 Types of Sprinkler Systems 11. Hand-Move or (Portable) System A portable sprinkler system has portable main line and laterals, and a portable pumping plant. It is designed to be moved from field to field, or to different pump sites in the same field and it may be designed to be moved manually or by mechanically power (Michael, 1983).Length of 75 mm to 150 mm diameter light weight piping and medium-pressure sprinklers mounted on risers. The field pipes (Laterals) designed to feed the sprinklers have riser out let at 7.5 m to 12m spacing. 12. Linear Move System The system is similar to center- pivot system in construction- except that neither end of the lateral pipe is fixed. Both of center- pivot and linear move systems are capable of achieving very high efficiencies of water application (Pair, 1968). The advantage of linear move system compared to center pivot that it can be used to irrigate or rectangular areas efficiently without any tosses.

13. Side-Roll System The side Roll system is linear move irrigation system, incorporates one sprinkler tailing for each sprinkler or the pipelines (Jensen, 1983). 14. Low Energy Precision Application System The system is similar to linear move irrigation system, but is different enough to deserve separate mention. The lateral line is equipped with drop tube and very low pressure orifice emission device discharging water just above ground surface into furrow(Zoldoske and Solomon, 1988). 15. Solid-Set System A solid- set system has laterals to eliminate their movement. The laterals are positioned in the field early in the crop season and remain for the entire season (Michael, 1983).

16. Permanent System A fully permanent system consists of permanently laid mains. Sub -mains and laterals, and stationary water source and pumping plant (Michael, 1983). 17. High Pressure Large Volume Sprinkler System Are operated with the pressure of 80 to 130 psi, the capacity of this sprinkler varies from 80 to 1000 gallon per minute (James, 1975). 18. Stationary or Fixed Sprinkler system This type is used in lawns, shrubbery, and green house system. 19. Perforated Sprinkler system Perforated sprinkler lines are designed to irrigate strip, between 35 and 45 feet in width with proper overlap to give a good uniform coverage (James, 1975). 20. Center Pivot Irrigation System The center- pivot irrigation system consists of a single linear of relatively large diameter composed of high galvanized light steel or aluminum pipe supported by a series of towers move on wheels. The time for system to revolve through one complete circle area can be range from half a day to many days. The lateral line, the faster, the end the lateral travels, and large the area irrigated by the end section (Zoldoske and Solomon, 1988). 2.6.3 Center Pivot System Components The center pivot irrigation is one of the modern irrigation methods that have been entered in Sudan, because it’s capable to improve climate, increase productivity and decrease operation costs of surface irrigation by reduce usable power. 12. Water Source Can be a river, a channel or bore hole (well). 13. Water Supply System The mainline can be PVC or PE(100 – 150 – 200 – 225 – 250 mm) in diameters. Portable or buried to the center- pivot base. 14. Towers Towers are used to support and suspend the lateral pipeline.

15. Wheels Wheels are needed to move the system around the pivot point. It is an available in different sizes which are suited with different types of soil. 16. Lateral Pipe Line The lateral pipeline is the main pipe at the center pivot system. It used to and water distribute the water into a number of nozzles through the length. 17. Sprinklers Suspended drop tubes at the height of 0.3 to 0.9 m above soil surface. 18. Riser Pipes Riser pipes are used to connect the sprinklers with the lateral pipeline. 19. Drive Units The drive units are mounted on wheels tracks and kids that are located 24.4m to 76.2m a part along the lateral pipes. Each drives has a power device mounted on it (Jenses, 1983). 20. Pumping and Power System Usually mid-size pumps from 1500 – 2500 L/Min are used to operate the entire pivot at once. Only low to moderate pressure is required. The pump can be diesel or electric, single or multiple stages (FAO, 2000). 21. Filtration Method Media or screen filtration is required based on the water quality and sprinkler nozzle size. 22. Fertilizer and Pesticides Storage (Fertigation Unit) It is small storage, located near the pivot. It is required to keep any mixed fertilizer or pesticides which must be sprayed upon the crop. 2.6.4Advantages of Center- Pivot Irrigation System 1. Water delivery is simplified through the use of a stationary pivot point. 2. Guidance and alignment are controlled at a fixed pivot point. 3. Relatively high water application uniformities are easily achieved under the continuously moving sprinklers.

4. After completing irrigation, the system is at the starting point for the next irrigation. 5. Achieving good irrigation management is simplified because accurate and timely application of water is made easy. 6. More accurate and timely applications of fertilizer and other chemicals are possible by applying them through the irrigation water. 7. Flexibility of operation makes it feasible to develop electric load management schemes (Rolland, 1982).

2.6.5 Disadvantages of Center Pivot Irrigation System 1. Not recommended for heavy soils with low infiltration rates 2. Difficult to transfer from field to field but not possible 3. Wheel track issues which can be handled 4. Designed to irrigate in a circle and not suitable for irrigation of ordinary shape field

2.7 Hydraulics principles of Center Pivot Irrigation System: 2.7.1 Total Area Irrigated

푄 퐴푡 = …………………………………………………….………………...… (2.1). 퐸푇푃×0.116

Where:

2 퐴푡 ≡ Total area (푚 )

푄 ≡Discharge (total discharge) (퐿/푠푒푐)

E ≡ System efficiency (70% or 90%)

푇푃 ≡ 푆푦푠푡푒푚Operating time (hr/day)

0.116 ≡ Constant (Sabri, 2007).

2.7.2 Number of Nozzles It is a total number of nozzles which suspended from the lateral pipeline.

퐿 n = ………………………………………………………...... … (2.2). 푁푠 Where:

n≡ Number of Nozzles.

L≡the length of lateral pipeline (m).

Ns ≡ Spaces between nozzles, (m) (Sabri, 2007).

2.7.3 Area Covered by the First Nozzles

퐴𝑖 = 휋(Ns)……………………………………………………………...….... (2.3). Where:

퐴𝑖 ≡ Area covered by the first nozzle which is nearest to the pivot point (푚2) (Sabri, 2007).

2.7.4 Required Discharge of Each Nozzle

퐴푛푑푤 푞푛 = ………………………………………...………………….....… (2.4). 3600 푇퐸푎 Where:

3 푞푛 ≡ Required discharge of each nozzle from 1 to n (푚 /푠푒푐).

2 퐴푛 ≡ Area can be covered by each nozzle from 2 to n(푚 ).

푑푤 ≡ Depth of water that must be added to crop daily (m).

T ≡Operating time, (hr/day).

Ea ≡ System efficiency (70% or 90%).

3600 ≡ Constant (Sabri, 2007).

2.7.5 Discharge of lateral pipe line

퐴푡푑푤 푄퐿= …………………………………………………………………….. (2.5). 3600푇퐸푎 Where:

3 푄퐿 ≡Lateral discharge (total discharge) (푚 /푠푒푐).

푑푤 ≡ Depth of water that must be added to crop daily (m).

T ≡ 푆푦푠푡푒푚operating time (hr/day).

Ea≡ System efficiency (depending on season) summer (70%) winter (90%) (Sabri, 2007).

2.7.6 Diameter of pipe line

D = √0.92푄퐿 …………..…………………………………………………….. (2.6). Where:

D ≡ Diameter of lateral (m).

3 푄퐿 ≡ Discharge of each nozzle from 1 to n (푚 /푠푒푐) (Sabri, 2007).

2.7.7 Diameter of pipe line in (inch) 퐷푚 퐷 = …………………...……………………….……………….…. (2.7). 𝑖푛푐ℎ 0.0254 Where: Dm ≡ Diameter of pipe line (m) 0.0254 ≡ Constant (Sabri, 2007). 2.7.8 Length of the pipe

푄 L = √ 퐿∗푇∗퐸푎∗3600 ………………………………………………………..…… (2.8). 휋푑푤 2.7.9 Pressure Head of the last Nozzle 푃 푃 = 푎 …………………………………………………………………… (2.9). ℎ푒푎푑 훾

Where:

푃푎 ≡ Operating pressure of last nozzle in Pascal (Jenses, 1983).

훾 ≡ 98102.1320

2.7.10 Total Dynamic Head of the Pump

퐸푝 = 퐻푠 + 푃 + ∑ ℎ퐿2 + ∑ ℎ퐿1 ± 푍푚 ……………...……………………... (2.10). Where:

퐸푝 ≡ Total dynamic head of the pump (m).

퐻푠 ≡ Static head of the pump (m).

5 ∑ ℎ퐿2 ≡ Head losses at the range of Re> 10 (m).

5 ∑ ℎ퐿1 ≡Head losses at the range of 푅푒 ≤ 10 (m).

푍푚 ≡ The height or depression of the surface (m). (Sabri, 2007).

2.7.11 Required Hydro Power of the Pump

푌푄퐻 푃 = ………………………………….……….……………….. (2.11). ℎ푦푑푟표 1000×0.7

푃ℎ푦푑푟표 ≡ Hydropower of the pump, (kW).

Y ≡ Specific weight of the water which is 9810 (푁/푚3).

H ≡ Total dynamic head of the pump (m).

1000 ≡ Constant to get the hydropower (kW).

0.7 ≡ Efficiency of the pump which 70% (Jenses, 1983).

CHAPTER THREE

MATERIAL AND MATHODS

3.1 Study site The study was carried out in Wad El-sheikh Agricultural Scheme for production of the Alfalfa and potatoes. The crop grown during the study period is Alfalfa. The scheme is located about 133 km of west Omdurman city, on the western bank of the Nile River at longitude 33.3°E, latitude16.4°Nandaltitude 380 m (ASL), the total area of the scheme is about 1680 hectare.

3.2 Soil The soil type in west Omdurman area is sand soil that leads to move the soil from place to another place. 3.3 Climate The region has a semi- desert climate. The weather is rainy in the summer, cold and dry in the winter, temperature declines gradually from November to March. The temperature in summer from April to October had been a high. 3.4 Features of the Center Pivot System The main features of the center pivot system which used in this scheme are: 3.4.1 Water Source The water that used in this system is drived from a well at depth of 228 m (750 ft) (Plate3.2). 3.4.2 Power and Pumping Unit The pumping unit used in the scheme was an internal combustion engine (250 hp), which provides the system with electrical power (420 voltage) required for the movement of the pivot system. The pump is normally a pump or a submersible pump fitted with usual accessories(mainline, sub mainline). The water is pumped from a well or a tube well, and the capacity of the existing pump (3000 cubic meter)is sufficient to provide the desired pressure (850 gallon per minute) at the nozzle or sprinkler head (1.1 liter per second), a separate pump may not be necessary for the system because source of water is a well(Plate3.3).

3.4.3 Flow-Meter The flow-meter with an average of (850 - 1000 gallon per minute per one irrigation), was fixed to the main pipe line to measure the operating pressure of the system per one irrigation (Plate 3.4). 3.4.4 Pivot Center It is a concrete foundation. A pipe line (250 (mm) check-out the unit in diameter) rises vertically upwards from ground level where it is connected to a rotating elbow shaped fitting(plate 3.5). 3.4.5 Drive Unit (Towers) It consists of a beam on which a drive motor and two wheels are mounted, at the top of each tower there is an electrical box which the electrical power is transferred to drive motor. The wheels are operated by drive motor via connecting rod and a gearbox (plate 3.6). 3.4.6 Mainline pipe The main line pipes of aluminum are suspended above the ground by the drive unit. The water is conveyed from the pivot through the pipe line, across the field till its edge. The center pivot system on which the study was implemented consisted of seven spans. The two spans are of 49m pipe length each 219 mm in diameter and the length for other five spans are 55 m and 219 mm in diameter (plate 3.7). 3.4.7 Sprinkler System It consists of 144 sprinklers connected at the top of the pipeline. The distance between sprinklers is 2 m(plate 3.8). 3.4.8 Fertigation Unit It consists of a tank with 7 푚3 in the capacity, chemical fertilizer that can dissolved in the irrigation water, making a solution through the pipe line by an injector pumps. The injector pump is fitted with a capacity regulator by which the appropriate volume at liquid can be measured (plate 3.9). 3.4.9 Control Panel The system is fully automated and controlled from a panel near the pivot or remotely from an office nearby. Time locks are used to start and stop the machine and many safety devices are used for protection (plate 3.10).

3.5 Data Analysis 3.5.1 Crop Water Requirement The Penman-Monteith formula was used to calculate the consumptive use of the reference crop evapotranspiration (ETo) for the study area, based on the local metrological data. The metrological data was obtained from Shambat Weather station, which includes; wind speed, sunshine, relative humidity, temperature, evaporation for period of (June to November 2015). This data was used to calculate crop water requirement using the CROPWAT software by following equation:

퐸푇푐 = 퐸푇° × 퐾푐…………………………………………………………...... (3.1).

Where:

퐸푇푐 ≡ Crop evapotranspiration, (mm/day)

퐸푇° ≡ Reference evapotranspiration, (mm/day)

퐾푐 ≡ Crop coefficient it depends on the stage and the season of growth and the season of growth, (Hussein 2014)

3.5.2 Crop Coefficient (푲풄)

Change in vegetation and ground cover mean that the 퐾푐varies during the growing period.

Only three periods in time of crop season are required to describe and construct퐾푐curve which are the initial stage extends from sowing until crop cover is about 10%, mid-season stage extends from 80 – 90% crops cover, and late season stage from full maturity to harvest (FAO,paper 56). 3.5.3 Soil moisture content The soil moisture content was determinate by using the gravimetric technique (Michael, 1978). Soil samples were taken before and after irrigation cycle from three different locations in each lateral. The samples (27 samples before and after each irrigation) were taken by an auger from three depths (0 – 20 cm), (20 – 40 cm), (40 – 60 cm). The samples collected were kept in polyethylene bags. The wet samples were weighted using a sensitive balance, and the weight of each soil sample was recorded (푀푚). The samples were then dried for 24 hours in an electric oven at 105℃. The dried soil samples reweighted with the same balance, and the

36 dry weight of each sample was recorded (푀푑). The moisture content on dry weight basis was calculated as the following: 푀 −푀 M% = 푚 푑×100……………………………………………………………….…… (3.2). 푀푑

Where:

M% ≡ Soil moisture content by weight %

푀푚 ≡ Weight of the wet sample (g)

푀푑 ≡ Weight of the dry sample (g)

3.5.4 Sprinkler Coverage (water depth) Measurement To measure the water depth and nozzle discharge samples were taken using 48 catch cans with 11 cm diameter and 8.5 cm depth to catch water. A measuring cylinder (100 ml and 550 ml) and graduated measuring tape 50 meter was used for adjusting the distance between catch cans.

Plate: (3.1) Experimental equipment’s

Plate: (3.2) Water Source Plate:(3.3 ) Pumping and Power Unit

Plate: (3.4) Flow- Meter

Plate: (3.5) Pivot Center Plate: (3.6) Drive Unit

Plate: (3.7) Mainline pipe Plate: (3.8) Sprinkler System (Head)

Plate: (3.9) Fertigation Unit Plate: (3.10) Control Panel

3.6 Hydraulic Performance The experiment was conducted at a 30%, 60% and 90% of system moving per 60 second with 48 catch cans with 11 cm diameter and 8.5 cm depth. The cans were placed at equal distances (6 m) in the straight line from pivot point toward a direction and the center pivot was allowed to pass over them, and volumetric measurements cylinders were used to measuring water being caught. The system operates for period of 20 hour per day.

Uniformity coefficient, distribution uniformity of the center pivot irrigation system were measured using catch cans.

3.6.1 Coefficient of Uniformity (푪풖)

The Christiansen’s coefficient of uniformity (퐶푢) expressed as a percentage. As follows (Christiansen, 1941):

n ∑i=1 │vi−v̅│ 퐶푢%= [1 − n ]× 100 ……………………………………………….………... (3.3) ∑i=1 vi

Where:

퐶푢≡ Christiansen‘s coefficient of uniformity (%) vi≡ Individual catch can measurement (mm) v̅ ≡ Average volume of application over all catch cans (mm) n≡ number of observations

3.6.2 Uniformity Distribution (푫풖) The distribution uniformity was computed by dividing the average low quarter depth of water received by average depth of water received in all cans. This was made by the following equation as suggested by Zolodiske and Solomon (1988). Averagelowquarterdepth of water received 퐷 % = × 100 …………….………………… (3.4). 푢 Averagedepthof water received in all cans

Where:

퐷푢 ≡ Distribution Uniformity (%)

3.6.3 Application Efficiency ( 푬풂) The application efficiency of the center pivot irrigation system were calculated using the average depth of application as monitored by the systems flow meter (푊푓) and the average depth of water caught in the cans (푊푠) then the application efficiency (퐸푎 %) was calculated using the following formula as suggested by Israelsen (1962) :

퐖퐬 퐸푎% = × 100 ……………………………………….…………..…………………… (3.5). 퐖퐟

Where:

퐸푎≡Application Efficiency

푊푠≡the average depth of water caught in the cans

푊푓 ≡the average depth of application as monitored by the systems flow meter

3.6.4 Irrigation Efficiency (E %) Irrigation efficiencies of center pivot irrigation system ware calculated using the application efficiency and distribution uniformity (Sabri, 2007). By the following formula: Irrigation Efficiency = application efficiency × distribution uniformity………………. (3.6).

3.6.5 Scheduling Coefficient (푺풄 %) Scheduling coefficient determines the critical area in the water applicant pattern. This is the area receiving the least amount of water, which is divided by the average amount of water applied through the irrigation area (Zoldoske and Solomon, 1988). 푆푐Was calculated as following: 1 푆 %= ×100 …………………………………………………………………...…… (3.7). 푐 Du

Where:

퐷푢 ≡ Distribution Uniformity

푆푐≡ Scheduling Coefficient

3.6.6 Nozzle Discharge A stop watch, calibrated containers and big catch can with 50 cm in diameter and 60 in depth was used. Volumetric measurement of water discharge was made by connecting the can to the nozzle and water was directed into the containers. The stop watch was used to record the time. 3.6.7 Percentage of Water Loss Water loss from the system was calculated by subtracting the average depth of water reaching the ground as determined in catch cans from the average depth of application as monitored by the system flow meter (Sabri, 2007).

Volume applied (m3) Average depth of application = …………………...... …...… (3.8). Area irrigated (m2)

Water Loss = Average depth of application – Average depth in catch cans…………….. (3.9).

water loss Percentage of water loss (%) = × 100 ………...... ….. (3.10). Averagedepth ofapplication

3.7 Economic Evaluation of the Center Pivot Irrigation System 3.7.1 Benefit to Cost Analysis A benefit- cost analysis (BCA) was computed for evaluating economic performance of the center pivot irrigation system, including calculating the net present value (NPV) of benefits and costs for the system. The benefit- cost ratio (BCR) for the system can be calculated by dividing the net present value (NPVB) of benefits by net present value (NPVC) of costs (Marwa, 2015).As follows equation:

풓 푩풕 ∑풓=풊 풕 BCR = (ퟏ+풓) ……………………………………………………………………..… (3.11). ∑풓 푪풕 풓=풊(ퟏ+풓)풕

Where:

BCR ≡ benefit cost ratio

퐵푡 ≡ Benefit in time t r≡ the discount rate

퐶푡 ≡ Cost in time

3.7.2 Cost Analysis The benefit to cost ratio (BCR) is directly compares benefits and costs, the (BCR) equations were used for that purposes (Marwa, 2015): 퐵푒푛푒푓𝑖푡푠 Benefit- Cost Ratio = …………………………………………….………..… (3.12). 퐶표푠푡푠

(퐵푒푛푒푓𝑖푡푠−퐶표푠푡푠) Return on Investment = ……………………………………...…...….. (3.13). 퐶표푠푡푠

Net Present Value = Benefits – Costs ……………….………………..……………….. (3.14).

CHAPTR FOUR

RESULTS AND DISCUSSION

4.1 Hydraulic Performance Evaluation

4.1.1 Coefficient of Uniformity (푪풖%)

The result indicated average value of (퐶푢%) was 71.8% for nine irrigations during the growing season (Table 4.1); this value is lower than the normally recommended for sprinkler system. Low values of 퐶푢 could be due to many reasons such as fitting, sprinklers are not rotated in good efficiency, lack in maintenance of irrigation system for the season.

Table (4.1) values of Coefficient of Uniformity

No. of Irrigations 퐶푢% 1 77.1 2 75.8 3 70.0 4 79.0 5 70.1 6 70.7 7 63.1 8 69.5 9 71.2 Average 71.8

4.1.2 Distribution Uniformity (푫풖%)

The average value of (퐷푢) was 63.5% for nine irrigations during the growing season (Table 4.2). These values for the system are considered low as compared to standard value of 74% reported by (Solomon, 1988). Lower (퐷푢) values were associated with wind speed and high relative humidity.

Table (4.2) Values of Distribution Uniformity

No. of Irrigations (퐷푢% 1 70.8 2 62.1 3 64.0 4 64.6 5 59.9 6 62.2 7 63.5 8 62.0 9 62.4 Average 63.5

4.1.3 Application Efficiency ( 푬풂%) Average application efficiency was 77.7% for nine irrigations during the growing season (Table 4.3). This value is lower than other values considered. Application efficiency affected by sprinklers rotation and nozzle discharge, water leakage from the system.

Table (4.3) values of Application Efficiency

No. of irrigations 퐸푎% 1 80.2 2 77.4 3 76.6 4 79.0 5 78.7 6 74.7 7 77.8 8 62.0 9 76.6 Average 77.7

4.1.4 Irrigation Efficiency (E %) The average irrigation efficiency was 48.6 %. This value is lower than the recommended. The lower value could be attributed to improper installation and lack of maintenance of the system (table 4.4).

Table (4.4) values of Irrigation Efficiency No. of Irrigations E % 1 60.5 2 52.1 3 50.9 4 46.2 5 45.8 6 44.6 7 48.3 8 43.6 9 45.9 Average 48.6

4.1.5 Scheduling Coefficient (Sc %) The Sc% values was found to be 1.5% on average; it’s was greater than the recommended, because it depends on (퐷푢) (table 4.5).

Table (4.5) values of Scheduling Coefficient (푆푐%)

No. of Irrigations 푆푐% 1 1.4 2 1.5 3 1.6 4 1.4 5 1.4 6 1.5 7 1.5 8 1.6 9 1.4 Average 1.5

4.1.6 Percentage of Water Losses The result showed that the water loss from the center pivot system by using equation (3.8) was 38.1 %. The higher percentage of water loss obtained in the system was due to wind drift, inadequate system pressure, and also as a result of error in setting, improper installation and operation of the system.

4.2 Crop Evapotranspiration (푬푻풄)

Using CROPWAT program (cropwat 8.0 windows version 4.3 FAO) 퐸푇0was found to be 6.4 mm/day, 퐾푐 was found to be 0.95, and 퐸푇푐was 6.08 mm/day during the late stage. 4.3 Soil Moisture Content Soil moisture content was determined by using gravimetric method and result showed that the average (27 samples before and after irrigation) soil moisture content ranging from 13.8 % to 7.1 % (Table 4.6). Table (4.6): Soil moisture content before and after irrigation Soil Depth (cm) Moisture % before irrigation Moisture % after irrigation 0.00 – 20.00 12.8 13.8 20.00 – 40.00 9.6 10.2 40.00 - 60.00 7.1 7.3

4.4 Available Water

Table (4.7): Available water before irrigation Depth (cm) M % BD VOL% Total Water (푚3) Available Water (푚3/ℎ푎)

20 12.8 1.16 14.8 219.8 200.1 40 9.6 1.17 11.2 125.8 101.8 60 7.1 1.31 9.3 86.5 60.4

Table (4.8): Available water after irrigation Depth (cm) M % BD VOL% Total Water (푚3) Available Water (푚3/ℎ푎)

20 13.8 1.16 16.0 256.1 236.4 40 10.2 1.17 11.9 142.0 117.2 60 7.3 1.31 9.6 91.8 65.7

According to the Table 4.8there is no significant difference between soil moisture content values before and after irrigation which means there was no deficit in available water for the crop.

4.5 Economic evaluation for producing fodder crop under Center Pivot 4.5.1 Economics of installing a new pivot irrigation system a breakdown of components costs for the irrigation system per 38 hectares, table (4.9) ownership and operating costs

Construction cost of one Pivot Point Initial Cost Years Useful Yearly Depreciation by (US$) Life by (US$) Ownership Costs

Complete Center Pivot Sprinkler 125,916 20 6,296 Irrigation System. Power Unit and pump 62,958 5 12,592 Well, at depth of 750 ft (228 m) 93,168

Operating Costs Repairs and Maintenances 15,528 20 776 Fuel, Oil 33,540

TOTAL COST 331,110 19,664 TOTAL COST PER HECTARE 8,713 517

4.5.2 Crop Yield The production and yield of the cultivated area (t/ha) was calculated by the following equation: Production for one cutting/38 hectare = No. of Bales × Bale weight

4600 bales × 20 kg= 92000 kg/1000 = 92 t/38 ha

Yield for one cutting per 38 hectare= tone/38 hectare

92 tone/ 38 hectare = 2.42 t/ha

Total yield per year = 92 tone × 9 Month = 828 t/year

4.5.3 Crop Benefit Benefit for one cutting = 92 tone × 466US$ = 42,872 US$ Benefit for one cutting per hectare = 2.42 t × 466 US$ = 1,127US$

Benefit per year = 92 tone × 9 month × 466 US$ = 385,848 US$/year

Benefit = Gross Value – Total Cost

= 385,848 US$ - 331,110 US$ = 54,738 US$/year (table 4.9)

4.5.4 Cost Analysis Calculating benefit- cost ratio, return on investment and net present value, using the equations: (3.12), (3.13) and (3.14), respectively. ퟑퟖퟓ,ퟖퟒퟖ 푼푺$ Benefit- Cost Ratio = = 1.2 % ퟑퟑퟏ,ퟏퟏퟎ 푼푺$

(ퟑퟖퟓ,ퟖퟒퟖ 푼푺$−ퟑퟑퟏ,ퟏퟏퟎ 푼푺$) Return on Investment = = 16.5 % ퟑퟑퟏ,ퟏퟏퟎ 푼푺$

Net Present Value = 385,848US$ – 331,110US$ = 54,738 US$

4.5.5 Benefit to Cost Analysis (BCA) Calculating benefit- cost ratio for the first year shows the following value by using equation (3.11).

ퟑퟖퟓ,ퟖퟒퟖ 푼푺$ ퟑퟖퟓ,ퟖퟒퟖ 푼푺$ ∑ ∑ ퟏퟗퟐ,ퟗퟐퟒ 푼푺$ BCR = (ퟏ+ퟏ) = ퟐ = = 1.2 % ∑ퟑퟑퟏ,ퟏퟏퟎ 푼푺$ ∑ퟑퟑퟏ,ퟏퟏퟎ 푼푺$ ퟏퟔퟓ,ퟓퟓퟓ 푼푺$ (ퟏ+ퟏ) ퟐ

The economic evaluation of center pivot irrigation system covered 38 hectares including ownership and operating for the first year showed that Benefit- Cost Ratio gave value of 1.2 %, Return of Investment was 16.5 % and the Net Present Value was 54,738 US$. The results achieved from this study showed that the economic evaluation of this system was gainful and benefit.

CHAPTER FIVE

CONCLUSIONS AND RECOMMENDATIONS

5.1 Conclusions From the results of this study the following conclusions can be drawn: 1. Low values of uniformity coefficient and uniformity of distribution are attributed to the effect of riser and support an effect of wind. 2. Average application efficiency has been found low in value. 3. Irrigation efficiency of the center pivot irrigation system at the study area was less compared to recommended value; this could due to low application efficiency and distribution uniformity. 4. Scheduling coefficient was found to be 1.5%, as a result of low distribution uniformity. 5. Percentage of water losses was high, as a result of setting error and improper installation of the system. 6. Net present value for the center pivot irrigation system for the first year was gainful.

5.2 Recommendations Based on the results obtained and the conclusions drawn from this study the following recommendations can be made: 1. To obtained high application efficiency, high uniformity coefficient, high uniformity of distribution and low percentage of water losses the sprayers should be changed and must be operated under the recommended pressure. 2. Negative effect of wind should be reduced by made high and strong shelter belt. 3. Operating of the pressure regulator for all sprayers should be checked and replaced when needed. 4. Taxes and labor costs must be included in the evaluation, to show last pattern for economic evaluation of center pivot irrigation system. 5. Further studies in center pivot irrigation systems are necessary for better understanding and evaluation.

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Appendices

Appendix (A): Climate Data

Appendix (푨ퟏ) Day Wend Speed Sunshine Temp Temp Average Evaporation (km/hr) Duration Max. Min. Temp. Piche tube (%) (푪°) (푪°) (푪°) (mm)

1 4.95 81 39.0 25.5 32.3 12.0 2 4.47 46 39.5 28.0 33.8 09.0 3 4.24 77 41.5 26.0 33.8 10.0 4 4.47 75 42.0 27.5 34.8 10.0 5 4.97 77 42.5 25.0 33.8 14.0 6 4.00 59 41.7 27.0 34.4 11.0 7 4.15 59 37.7 27.0 32.4 09.0 8 4.45 67 40.5 26.5 33.5 14.2 9 5.07 50 40.8 28.5 34.7 14.0 10 5.49 81 41.0 26.5 33.8 12.0 11 4.39 73 41.5 26.0 33.8 13.0 12 4.72 43 41.2 25.0 33.1 12.0 13 4.79 76 41.5 27.0 34.3 11.0 14 5.16 44 41.1 26.0 33.6 10.0 15 4.76 71 42.0 27.0 34.5 10.0 16 4.38 79 42.0 27.0 34.5 10.0 17 4.51 47 41.2 28.5 34.9 13.0 18 4.65 77 40.5 27.0 33.8 11.0 19 4.62 70 28.5 26.5 27.5 12.0 20 4.49 62 39.5 25.0 32.3 12.0 21 4.00 79 39.7 26.0 32.9 11.0 22 4.80 71 40.5 25.5 33.0 09.0

23 4.60 79 40.6 27.5 34.1 10.0 24 4.58 17 38.7 29.5 34.1 11.0 25 4.93 79 41.0 27.0 34.0 10.0 26 4.35 64 41.0 29.5 35.3 14.0 27 4.14 77 39.5 27.0 33.3 14.2 28 5.05 83 37.0 26.0 31.5 13.0 29 5.10 84 35.0 24.0 29.5 11.0 30 5.90 90 35.0 23.0 29.0 12.0 Total 140.2 2037 1193.2 797.5 996.3 344.4 Average 4.67 67.91 39.77 26.58 33.21 11.48

Appendix (푨ퟐ): Day Relative Humidity (%) Relative Humidity (%) Average Relative At 9:00 AM At 9:00 PM Humidity (%)

1 50 33 41.5 2 55 40 47.5 3 55 37 46 4 45 45 45 5 49 37 43 6 47 35 42 7 55 53 54 8 47 40 43.5 9 52 38 40 10 45 37 41 11 31 36 33.5 12 40 34 37 13 44 37 40.5 14 59 45 53 15 45 45 45

16 50 45 47.5 17 60 43 51.5 18 50 37 43.5 19 54 49 51.5 20 59 40 49.5 21 56 49 52.5 22 41 39 40 23 41 39 40 24 57 54 55.5 25 54 45 49.5 26 49 41 45 27 34 33 33.5 28 31 21 26 29 30 22 26 30 30 19 24.5 Total 1315 1168 1291.5 Average 43.83 38.93 43.05 Appendix (B): Soil Moisture Content

Appendix (푩ퟏ) Sample Depth (cm) Wet weight (g) Dry weight (g) Moisture content (%) 1 0 – 20 28.0 23.3 16.8 2 20 – 40 28.0 25.1 10.4 3 40 – 60 28.0 25.4 9.3 4 0 – 20 28.0 24.4 12.9 5 20 – 40 28.0 25.4 9.3 6 40 – 60 28.0 25.7 8.2 7 0 – 20 28.0 24.7 11.8 8 20 – 40 28.0 26.2 6.4 9 40 – 60 28.0 27.0 3.6

10 0 – 20 28.0 26.6 5.0 11 20 – 40 28.0 26.7 4.6 12 40 – 60 28.0 26.9 4.0 13 0 – 20 28.0 26.2 6.4 14 20 – 40 28.0 26.9 4.0 15 40 – 60 28.0 27.1 3.2 16 0 – 20 28.0 23.5 16.1 17 20 – 40 28.0 26.6 5.0 18 40 – 60 28.0 27.4 2.1 19 0 – 20 28.0 25.1 10.4 20 20 – 40 28.0 26.3 6.1 21 40 – 60 28.0 26.5 5.4 22 0 – 20 28.0 24.8 11.4 23 20 – 40 28.0 25.6 8.6 24 40 – 60 28.0 26.5 5.4 25 0 – 20 28.0 25.3 9.4 26 20 – 40 28.0 25.8 7.9 27 40 – 60 28.0 27.3 2.5

Appendix (푩ퟐ) Sample Depth (cm) Wet weight (g) Dry weight (g) Moisture content (%) 1 0 – 20 28.0 24.0 14.3 2 20 – 40 28.0 24.5 12.5 3 40 – 60 28.0 25.1 10.4 4 0 – 20 28.0 23.8 15.0 5 20 – 40 28.0 24.6 12.1 6 40 – 60 28.0 25.3 10.0 7 0 – 20 28.0 24.3 13.1 8 20 – 40 28.0 25.5 8.9

9 40 – 60 28.0 26.0 7.1 10 0 – 20 28.0 24.3 13.2 11 20 – 40 28.0 25.4 9.3 12 40 – 60 28.0 25.9 7.5 13 0 – 20 28.0 24.6 12.1 14 20 – 40 28.0 25.4 9.3 15 40 – 60 28.0 25.7 8.2 16 0 – 20 28.0 24.6 12.1 17 20 – 40 28.0 25.1 10.4 18 40 – 60 28.0 25.7 8.2 19 0 – 20 28.0 24.4 12.9 20 20 – 40 28.0 25.0 10.7 21 40 – 60 28.0 25.5 9.0 22 0 – 20 28.0 24.7 11.9 23 20 – 40 28.0 25.2 10.0 24 40 – 60 28.0 25.8 7.9 25 0 – 20 28.0 24.7 11.7 26 20 – 40 28.0 25.1 10.4 27 40 – 60 28.0 25.8 7.9

Appendix (푩ퟑ) Sample Depth (cm) Wet weight (g) Dry weight (g) Moisture content (%) 1 0 – 20 28.0 23.2 17.1 2 20 – 40 28.0 25.1 10.4 3 40 – 60 28.0 25.5 8.3 4 0 – 20 28.0 23.4 16.4 5 20 – 40 28.0 25.0 10.7 6 40 – 60 28.0 25.4 9.3

7 0 – 20 28.0 24.7 11.8 8 20 – 40 28.0 26.2 6.4 9 40 – 60 28.0 27.0 3.6 10 0 – 20 28.0 23.3 16.8 11 20 – 40 28.0 26.7 6.1 12 40 – 60 28.0 26.9 4.0 13 0 – 20 28.0 26.2 6.4 14 20 – 40 28.0 26.9 4.0 15 40 – 60 28.0 27.1 3.2 16 0 – 20 28.0 23.5 16.1 17 20 – 40 28.0 26.6 5.0 18 40 – 60 28.0 27.4 2.1 19 0 – 20 28.0 25.1 10.4 20 20 – 40 28.0 26.3 6.1 21 40 – 60 28.0 26.5 5.4 22 0 – 20 28.0 24.8 11.4 23 20 – 40 28.0 25.6 8.6 24 40 – 60 28.0 26.1 6.8 25 0 – 20 28.0 25.3 9.4 26 20 – 40 28.0 25.6 8.6 27 40 – 60 28.0 26.2 6.4

Appendix (푩ퟒ) Sample Depth (cm) Wet weight (g) Dry weight (g) Moisture content (%) 1 0 – 20 28.0 23.3 17.8 2 20 – 40 28.0 25.1 10.0 3 40 – 60 28.0 25.4 9.3 4 0 – 20 28.0 24.4 12.9

5 20 – 40 28.0 25.4 10.4 6 40 – 60 28.0 25.7 8.9 7 0 – 20 28.0 24.7 11.8 8 20 – 40 28.0 26.2 10.4 9 40 – 60 28.0 27.0 9.3 10 0 – 20 28.0 26.6 16.4 11 20 – 40 28.0 26.7 4.6 12 40 – 60 28.0 26.9 4.0 13 0 – 20 28.0 26.2 6.4 14 20 – 40 28.0 26.9 4.0 15 40 – 60 28.0 27.1 3.2 16 0 – 20 28.0 23.5 16.1 17 20 – 40 28.0 26.6 5.0 18 40 – 60 28.0 27.4 2.1 19 0 – 20 28.0 25.1 10.4 20 20 – 40 28.0 26.3 6.1 21 40 – 60 28.0 26.5 5.4 22 0 – 20 28.0 24.8 11.4 23 20 – 40 28.0 25.6 8.6 24 40 – 60 28.0 26.5 5.4 25 0 – 20 28.0 25.3 9.4 26 20 – 40 28.0 25.8 7.9 27 40 – 60 28.0 27.3 6.4

Appendix (푩ퟓ) Sample Depth (cm) Wet weight (g) Dry weight (g) Moisture content (%) 1 0 – 20 28.0 24.0 14.3 2 20 – 40 28.0 24.5 12.5 3 40 – 60 28.0 25.1 10.4 4 0 – 20 28.0 23.8 15.0 5 20 – 40 28.0 24.6 12.1 6 40 – 60 28.0 25.3 10.0 7 0 – 20 28.0 24.3 13.1 8 20 – 40 28.0 25.5 8.9 9 40 – 60 28.0 26.0 7.1 10 0 – 20 28.0 24.3 13.2 11 20 – 40 28.0 25.4 9.3 12 40 – 60 28.0 25.9 7.5 13 0 – 20 28.0 24.6 12.1 14 20 – 40 28.0 25.4 9.3 15 40 – 60 28.0 25.7 8.2 16 0 – 20 28.0 24.6 12.1 17 20 – 40 28.0 25.1 10.4 18 40 – 60 28.0 25.7 8.2 19 0 – 20 28.0 24.4 12.9 20 20 – 40 28.0 25.0 10.7 21 40 – 60 28.0 25.5 9.0 22 0 – 20 28.0 24.7 11.9 23 20 – 40 28.0 25.2 10.0 24 40 – 60 28.0 25.8 7.9 25 0 – 20 28.0 24.7 11.7 26 20 – 40 28.0 25.1 10.4 27 40 – 60 28.0 25.8 7.9

Appendix (푩ퟔ) Sample Depth (cm) Wet weight (g) Dry weight (g) Moisture content (%) 1 0 – 20 28.0 24.0 14.3 2 20 – 40 28.0 24.5 12.5 3 40 – 60 28.0 25.1 10.4 4 0 – 20 28.0 23.8 15.0 5 20 – 40 28.0 24.6 12.1 6 40 – 60 28.0 25.3 10.0 7 0 – 20 28.0 24.3 13.1 8 20 – 40 28.0 25.5 8.9 9 40 – 60 28.0 26.0 7.1 10 0 – 20 28.0 24.3 13.2 11 20 – 40 28.0 25.4 9.3 12 40 – 60 28.0 25.9 7.5 13 0 – 20 28.0 24.6 12.1 14 20 – 40 28.0 25.4 9.3 15 40 – 60 28.0 25.7 8.2 16 0 – 20 28.0 24.6 12.1 17 20 – 40 28.0 25.1 10.4 18 40 – 60 28.0 25.7 8.2 19 0 – 20 28.0 24.4 12.9 20 20 – 40 28.0 25.0 10.7 21 40 – 60 28.0 25.5 9.0 22 0 – 20 28.0 24.7 11.9 23 20 – 40 28.0 25.2 10.0 24 40 – 60 28.0 25.8 7.9 25 0 – 20 28.0 24.7 11.7 26 20 – 40 28.0 25.1 10.4 27 40 – 60 28.0 25.8 7.9

Appendix (C): Measuring Water Depth

Appendix (푪ퟏ): Running 30% Span 1 Can Water depth ( mm) Water depth ( mm) Water depth ( mm) 1 66 78 68 2 191 100 178 3 98 103 112 4 100 178 180 1 5 111 121 120 6 150 128 132 7 175 197 200 8 122 122 117 Span 2 Can Water depth ( mm) Water depth ( mm) Water depth ( mm) 9 111 122 112 10 172 161 111 11 150 153 150 12 133 130 198 2 13 160 155 133 14 115 120 120 15 120 115 131 16 111 110 119 Span 3 Can Water depth ( mm) Water depth ( mm) Water depth ( mm) 17 175 167 149 18 167 161 172 19 150 145 214 20 111 116 150 21 170 111 173 3 22 150 170 128 23 172 149 165 24 123 134 123

Span 4 Can Water depth ( mm) Water depth ( mm) Water depth ( mm) 25 221 232 204 26 172 192 174 27 232 230 211 28 120 125 179 4 29 119 190 99 30 83 87 118 31 166 160 114 32 170 171 100 Span 5 Can Water depth ( mm) Water depth ( mm) Water depth ( mm) 33 141 139 151 34 140 142 165 35 120 89 165 36 140 128 78 37 138 130 120 5 38 210 140 114 39 250 221 129 40 211 198 100 Span 6 Can Water depth ( mm) Water depth ( mm) Water depth ( mm) 41 135 130 155 42 133 147 141 43 138 132 140 44 182 180 130 6 45 130 149 139 46 160 77 182 47 100 97 112 48 88 70 85

Appendix (푪ퟐ): Running 60% Span 1 Can Water depth ( mm) Water depth ( mm) Water depth ( mm) 1 30 22 42 2 20 28 32 3 90 93 51 4 64 36 46 1 5 43 62 91 6 36 43 30 7 54 53 28 8 60 63 50 Span 2 Can Water depth ( mm) Water depth ( mm) Water depth ( mm) 9 39 40 38 10 64 43 45 11 30 41 37 12 32 33 38 2 13 42 31 49 14 43 63 70 15 40 39 88 16 51 21 19 Span 3 Can Water depth ( mm) Water depth ( mm) Water depth ( mm) 17 39 38 65 18 58 59 48 19 44 44 96 20 76 32 75 21 71 42 75 3 22 73 79 88 23 60 61 45 24 57 23 49 Span 4 Can Water depth ( mm) Water depth ( mm) Water depth ( mm) 25 52 45 46

26 58 90 93 27 91 46 86 28 79 65 79 4 29 78 45 80 30 83 57 74 31 29 72 91 32 30 51 31 Span 5 Can Water depth ( mm) Water depth ( mm) Water depth ( mm) 33 78 69 71 34 46 58 68 35 52 57 71 36 49 47 75 37 68 60 87 5 38 53 80 44 39 46 39 44 40 49 29 27 Span 6 Can Water depth ( mm) Water depth ( mm) Water depth ( mm) 41 46 43 58 42 85 54 61 43 54 59 74 44 58 60 61 6 45 55 72 59 46 46 54 32 47 14 26 20 48 16 19 21

Appendix (푪ퟑ): Running 90% Span 1 Can Water depth ( mm) Water depth ( mm) Water depth ( mm) 1 15 18 14 2 83 30 44 3 48 46 78 4 24 80 29 5 42 40 42 1 6 32 43 39 7 37 44 48 8 25 21 19 Span 2 Can Water depth ( mm) Water depth ( mm) Water depth ( mm) 9 23 17 22 10 24 22 28 11 40 25 29 12 28 30 32 13 20 19 21 2 14 17 18 22 15 24 20 31 16 29 32 20 Span 3 Can Water depth ( mm) Water depth ( mm) Water depth ( mm) 17 45 19 62 18 33 31 29 19 40 40 41 20 37 41 40 21 36 36 34 3 22 38 37 38 23 23 24 38 24 35 35 22 Span 4 Can Water depth ( mm) Water depth ( mm) Water depth ( mm) 25 49 20 45

26 41 70 73 27 48 27 27 28 33 44 43 4 29 48 21 23 30 65 23 22 31 27 24 26 32 43 31 36 Span 5 Can Water depth ( mm) Water depth ( mm) Water depth ( mm) 33 21 22 19 34 24 24 26 35 25 26 24 36 36 38 41 37 22 21 38 5 38 51 48 39 39 43 48 36 40 32 30 27 Span 6 Can Water depth ( mm) Water depth ( mm) Water depth ( mm) 41 30 32 38 42 43 41 45 43 25 28 27 44 26 24 17 6 45 44 42 40 46 43 45 46 47 12 16 21 48 11 13 23