A Computer Model for Irrigation Water Indenting and Optimization of Minor Canal Operation

ABSTRACT This study was carried out with objectives of developing a proper decision aid for irrigation indenting of multiple crop rotation based on Penman- Montieth equation( 1994) and amenable for the format of meteorological data of the Sudan. Consequently the study developed a mathematical simulation of canal operation for the purpose of optimization of water allocation within such a canal. Linear programming algorithm was made to optimize irrigation water allocation between different outlets in the irrigation canal under the constraints of fixed canal capacity and irrigation interval. The model was coded in a personal computer using Excel – visual basic application language (VBA ). These models were verified statistically in comparison with published models. Both water indent and allocation modules were applied to the real cases of wet and dry regions of Gezira Scheme – Sudan. The modules were applied to estimate water indent and for sequencing canal outlets for the cases of early and peak season at Sunni Minor canal and Ugud Minor canal. The model sensitivity to changes in outlet - inflow rate ( working time per outlet ) was made for the said two cases to XII conclude the developed model capabilities to optimize water scheduling and allocation process which can be used to save irrigation water during early stages and to upgrade the operation of minor canals in the irrigated schemes in the Sudan.

TABLE OF CONTENTS

DEDICATION …………………………………………………………………....ii

ACKNOWLEDGMENT …...……………………………………………………iii

TABLE OF CONTENT …………………………………………………………iv

LIST OF TABLES ………………………………………………………………vii

LIST OF FIGURES ………..…………………………………………………….ix

ABSTRACT …….……………………………………………………………….xii

ABSTRACT (Arabic) …………………………………………………………..xiv

CHAPTER ONE.......................................................................................................1

INTRODUCTION.....................................................................................................1

1.1 BACKGROUND AND JUSTIFICATION.................................................................................1

1.2 PROBLEM IDENTIFICATION.................................................................................................2

1.3 STUDY OBJECTIVES..............................................................................................................4

CHAPTER TWO......................................................................................................6

REVIEW OF LITERATURE..................................................................................6

2.1 ESTIMATION OF CROP WATER DEMAND.........................................................................6

2.1.1 Determination of reference evapotranspiration (ETo)..............................7

2.1.2 Determination of crop water requirements (ETc).....................................9

2.1.3 FAO Method for Determination of Crop Coefficient (Kc).....................10

2.1.3.1 FAO method for determination of Kcmid:-...................................................12

2.1.3.2 Crop coefficient for the end or the late season stage (Kc end).............12

2.1.4 Construction of the Kc curve ……………………………….....

…………….13

2.2 LENGTH OF GROWING STAGES........................................................................................15

2.3 DETERMINATION OF IRRIGATION EFFICIENCY AND LOSSES...................................16

2.4 DETERMINATION OF EFFECTIVE RAINFALL.................................................................19

2.5 ESTIMATION OF WATER INDENT (WATER ORDER) IN THE SUDAN........................21

2.6 SYSTEMS OF CANAL WATER DELIVERY AND ALLOCATION....................................23

2.7 OPERATIONAL OBJECTIVES IN IRRIGATION DELIVERY SYSTEM............................28

2.8 THE SYSTEM OF WATER DELIVERY AND ALLOCATION IN SUDAN:-.....................29

IV

2.9 OPERATION OF THE MINOR CANAL...............................................................................35

2.10 LINEAR PROGRAMMING TECHNIQUE FOR WATER ALLOCATION.........................37

CHATER THREE..................................................................................................41

MATERIALS AND METHODS...........................................................................41

3.1 THE STUDY AREA................................................................................................................41

3.2 THE STUDY SITES:...............................................................................................................41

3.3 DATA COLLECTION.............................................................................................................45

3.3.1 Meteorological data ................................................................................ 45

3.3.2 Agricultural data: .................................................................................... 45

CHAPTER FOUR...................................................................................................52

MODEL DEVELOPMENT...................................................................................52

4.1 GENERAL...............................................................................................................................52

4.2 THE PROGRAMME LIMITATIONS:....................................................................................53

4.3 THE PROGRAMME STRUCTURE........................................................................................53

4.3.1 Programme technique and style .............................................................. 53

4.3.2 Programme technical specification: ........................................................ 54

4.4 PROGRAMME ALGORITHM................................................................................................54

4.4.1 Reference evapotranspiration (ETo) module .......................................... 54

4.4.2 Crop Coefficient (Kc) module ................................................................ 60

4.4.3 Effective precipitation (Pe) module ........................................................ 87

4.4.4 Crop water requirements module ............................................................ 87

4.4.5 Irrigation water need module .................................................................. 91

4.4.6 Indenting module .................................................................................... 91

4.4.7 The optimization model .......................................................................... 91

CHAPTER FIVE....................................................................................................98

RESULTS AND DISCUSSION.............................................................................98

5.1 VERIFICATION OF THE MODEL........................................................................................98

5.1.1 Determination of ETO ............................................................................ 98

5.1.2 Crop coefficient (KC) ............................................................................. 98

5.2 VERIFICATION OF THE INDENTING MODEL...............................................................108

V

5. 3 VERIFICATION OF THE CANAL OPERATION MODEL...............................................115

5. 4 APPLICATION OF CANAL OPERATION MODEL.........................................................115

5. 4.1 The Case of Sunni Canal:- .................................................................... 115

5-4-2 The Case of Ugud ................................................................................. 125

CHAPTER SIX.....................................................................................................135

CONCLUSIONS AND RECOMMENDATIONS..............................................135

6-1- CONCLUSOINS..................................................................................................................135

6.2 – RECOMMENDATIONS....................................................................................................135

REFERENCES......................................................................................................137

APPENDICES.......................................................................................................145

 APPENDIX I………………………………………………………………...…146

APPENDIX II………………………...…………………………………….……160