improving operational performance and management ...

IMPROVING OPERATIONAL PERFORMANCE AND MANAGEMENT OF CANAL IRRIGATION SYSTEM USING HYDRAULIC MODELING

SUBMITTED BY

JAVAID AKHTAR TARIQ (2005-PhD-CEWRE- 05)

FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN WATER RESOURCES ENGINEERING

CENTER OF EXCELLENCE IN WATER RESOURCES ENGINEERING

University of Engineering and Technology, Lahore, Pakistan 2010

IMPROVING OPERATIONAL PERFORMANCE AND MANAGEMENT OF CANAL IRRIGATION SYSTEM USING HYDRAULIC MODELING by JAVAID AKHTAR TARIQ 2005-PhD-CEWRE- 05 A dissertation submitted in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY IN WATER RESOURCES ENGINEERING Thesis Examination Date: _______________

Internal Examiner Prof. Dr. Muhammad Latif) Director, Center of Excellence In Water Resources Engineering University of Engineering & Technology, Lahore.

External Examiner (Prof. Dr. Bakhshal Khan Lashari) Director, Institute of Irrigation & Drainage Engineering, Mehran University of Engineering & Technology. Janshroo, Sindh.

(Professor Dr. Muhammad Latif) Director

CENTER OF EXCELLENCE IN WATER RESOURCES ENGINEERING

University of Engineering and Technology, Lahore, Pakistan 2010

This thesis was evaluated by the following Examiners: External Examiners: From Abroad: (i)

Dr. Bart Schultz, Professor, Department of Water Resources and Hydraulic Engineering, International Institute for Infrastructural, Hydraulic and Environmental Engineering (IHE). Delft. The Netherlands Email : [email protected]

(ii)

Dr. Chandra A. Madramootoo, Professor, Department of Bioresource Engineering and Brace Centre for Water Resources Management, McGill University. Macdonald Campus. Canada. Email: [email protected]

From Pakistan: Prof. Dr. Bakhshal Khan Lashari, Director, Institute of Irrigation & Drainage Engineering, Mehran University of Engineering & Technology. Jamshroo, Sindh -76062. E Mail: [email protected]

Internal Examiner: Prof. Dr. Muhammad Latif, Director, Center of Excellence in Water Resources Engineering, University of Engineering & Technology, Lahore. E Mail: [email protected]

ABSTRACT

Water resources development and management acquired new dimensions in Pakistan. Recently, the Government of Pakistan has taken strategic initiatives and primarily focused on governance, decentralization and participation of the farmers by transforming the Provincial Irrigation Department (PID) to the Frontier Irrigation and Drainage Authority (FIDA). Management responsibilities are decentralized at canal command level to Area Water Boards (AWBs) and most of the existing functions at distributary level are performed by the farmer’s organizations (FOs). Recently six distributaries have been handed over to the farmer organizations under the irrigation management transfer (IMT) programme in Swat Canal Area Water Board (SCAWB).

The study was conducted to analyse the operational performance using hydraulic simulation modeling. To assess the impact of IMT on the performance of the irrigation system a database oriented irrigation management information system (IMIS) technique has been developed and utilized. The Simulation of Irrigation Canal (SIC) hydrodynamic model was used to analyse the improved operational scenarios for the irrigation systems operation at distributary level, to provide the system managers and farmers organizations to update the managerial control and plan operational activities through improved understanding of the system. Results of the study revealed that irrigation supplies are in excess of the crop water requirements. The relative water supply (RWS) index varies from 1.66 to 2.02 during summer, whereas in winter it varies from 2.22 to 2.55. The delivery performance ratio (DPR) during summer varies from 0.78 to 0.83 and in winter from 0.63 to 0.73. Irrigation supplies were reliable over the whole growing season. Due to modernization of the irrigation systems and enhanced water allowance, the annual cropping intensity and yield have increased significantly. There is a prominent increase in yield of maize (40 percent), sugarcane (55 percent) and wheat (43 percent) while the cropping intensity has increased by 25 percent.

iv

The Irrigation service fee (ISF) collection analysis indicated that all the FOs performed well during the first year (2004-05) of IMT and recovered 60 percent of the assessed ISF; whereas during the 2005-06 and 2006-07, ISF collected was very low. From these results it is evident that chances of successful cost recovery do not seem to be high.

Operational and regulation aspects of the main system also play a pivotal role in overall irrigation water management aspects. The SIC model was used to evaluate the effectiveness of physical infrastructures of the Chowki Distributary. Open flume outlets along the distributary behave as hyper-proportional irrespective of their position. The head bifurcator outlets are behaving hyper-proportional, whereas middle ones as perfect proportional and tail end as sub-proportional. The trifurcator outlets are behaving as hyper-proportional. The major causes are construction inaccuracies in setting the crest level, which lead the outlets to draw more or less than the design discharge.

To improve the manual operation of the Chowki Distributary irrigation system, different operational strategies were investigated and quantified. From the results of this study, it is suggested to operate the distributary head regulator manually based on fixed frequency operation. It is recommended that from May to July, the distributary should be operated at 90-80 percent of design discharge, 90-75 percent of design discharge from August to October and 75-85 percent of design discharge from December to April to adjust the over delivery due to high water allowance.

Hydraulic committees at each of the distributary should be

established to operate the distributary according to crop demand. Awareness among the farmers should be created regarding the farm irrigation application methods to avoid over-irrigation and wastage of water.

v

ACKNOWLEDGMENTS

Research assignment is a wonderful experience, it trains one, how to identify and employ the available resources in the solution of practical problem. It also shows how human beings can cooperate and work together in so many pleasant ways to solve the socio technical problems. The present academic endeavor provided me an opportunity to understand many intricacies of operation of canal irrigation system after irrigation management transfer to farmers.

I would like to express my heartfelt gratitude to Professor Dr. Muhammad Latif, who has always given me encouragement and offered useful suggestions for my professional development. He provided much encouragement, motivation and good counsel throughout my dissertation research. I could not have had this education without him.

I wish to express my appreciation to Professor Dr. Muhammad Jamal Khan, Chairman, Department of Water Management, who made it possible for me to complete the doctorate and provided me an opportunity for training at IWMI (Pakistan) on Hydrodynamic Models under HEC funded project, Strengthening Department of Water Resources Management. I am grateful Engr. Sarfraz Munir for teaching whole heartedly and with full devotion the SIC Model and its operation during training at IWMI, Lahore.

I am immensely indebted to Engr. Wasim, Water Dispatch Officer (WDO), SCAWB, for his assistance on operation of modernized irrigation system with self regulating gates, their linkage with Pehur High Level Canal and discussions on decorated lunches offered by him at historical century old Gohati, Zam and Jagnnath Irrigation Rest Houses. Thanks are expressed to all Sub-engineers, Overseers and field

staff of the Operation and Regulation Cell, Gohati Sub

Division for their cooperation during the data collection period.

vi

I am thankful to Mr. Nubat Khan, President, Farmers Organization, Chowki Distributary, who invited me to his village and discussed in detail the pros and corns of FOs. He provided opportunity for interactions with Presidents of other farmers’ organizations (FOs) and with farmers. I am also indebted to the farmers of Yaqubi, Gumbd-II, Qasim-II, Toru, Chowki, and Pirsabak Distributaries, who shared their knowledge, history and social constraints of Irrigation Management Turnover (IMT) with me without hesitation. The interviews conducted were of purely academic nature for developing some research objectives and not to offend or defend parties involved in IMT and operation of irrigation system. I am extremely grateful to some farmers, who were interviewed with condition of anonymity and therefore their names are not mentioned to protect the privacy and identity.

Many thanks are extended to Dr. Tahir Sarwar, Engr. Nisar Ahmad, Dr. Muhammad Zubair Khan, and staff of Department of Water Management, for their cooperation and encouragement. Administrative help and cooperation extended during my studies at CERWRE by Mr. Abdul Ghaffar, Mr. Ehsan Khan, Mr. Javed Nisar, Mr. Zafar Iqbal and Mr. Umer Daraz is sincerely acknowledged.

Last and foremost, I would especially like to express my deepest appreciation, constant care, and endless, unconditional and limitless support, love and encouragement of my wife, Summerine, and son, Moiz for their patience in tolerating the duration of my studies.

Finally, I acknowledge the tremendous support which my mother has always given me throughout my life.

Friday, February 12, 2010 Bilal Hall, CEWRE-Lahore.

Javaid A. Tariq

vii

TABLE OF CONTENTS ABSTRACT ....................................................................................................iv ACKNOWLEDGEMENTS.................................................................................vi TABLE OF CONTENTS.................................................................................. viii LIST OF TABLES ........................................................................................... xiii LIST OF FIGURES ......................................................................................... xiv LIST OF ABRIVATION ................................................................................. xviii GLOSSARY ...................................................................................................xx CONVERSION OF UNITS............................................................................. xxii I

INTRODUCTION ................................................................................... 1 1.1 1.2 1.3 1.4 1.5

II

Historical Overview ..................................................................... 1 Recent Developments................................................................. 3 Problem Identification ................................................................. 4 Scope of the Study...................................................................... 6 Specific Objectives...................................................................... 8

REVIEW OF LITERATURE .................................................................. 9 2.1 2.2 2.3 2.4 2.5 2.6

Irrigation Management ................................................................ 9 Design and Management Interaction........................................ 13 Irrigation Management Information System (IMIS)................... 14 Irrigation Management Transfer ............................................... 15 Modernization of Irrigation Systems ......................................... 18 Flow Control in Irrigation Systems ............................................ 19 2.6.1 Canal Control Methods .................................................. 19 2.6.2 Upstream Control ........................................................... 21 2.6.3 Downstream Control ...................................................... 22

2.7 2.8 2.9

Performance Assessment......................................................... 23 Modeling Needs in Water Management ................................... 27 Hydraulic Modeling Software .................................................... 28 2.9.1 Branch-Network Dynamic Flow Model (BRANCH)........ 29 2.9.2 CANALMangement (CANALMAN) ............................... 30 2.9.3 CAlcul des Riveres MAilles (CARIMA) ......................... 30

viii

Table of Contents (Continued)

2.9.4 2.9.5 2.9.6 2.9.7 2.9.8 2.10

III

Dutch Flow (DUFLOW) ................................................. 32 Modelling Drainage and Irrigation System (MODIS) .... 33 Simulation of Irrigation Canals (SIC) ............................ 34 UnSteady Model (USM) ................................................ 34 ISIS Flow........................................................................ 35

Comparison of Irrigation Simulation Models............................. 37

MATERIAL AND METHODS ............................................................... 39 3.1

Upper Swat Canal Irrigation System......................................... 39

3.1.1 Pehur High Level Canal (PHLC) ................................... 40 3.1.2 Crop Based Irrigation Operation (CBIO) Implementation .................................................. 43 3.1.3 Institutional Setup........................................................... 44 3.2

Proposed Irrigation Management Information System ............. 44 3.2.1 Data Structures .............................................................. 47 3.2.2 Method of Information Generation… ............................. 48

3.3

Data Collection Methodology.................................................. ..49 3.3.1 3.3.2 3.3.3 3.3.4 3.3.5

3.4

Performance Indicators............................................................. 59 3.4.1 3.4.2 3.4.3

3.5

Description of Selected Site ........................................ 49 Calibration of Hydraulic Structures.............................. 50 Discharge Measurement ............................................. 51 Metrological Data ........................................................ 55 Cropping Pattern, Intensity and Crop Yield ................ 57

Relative Water Supply (RWS) .................................... 59 Delivery Performance Ratio (DPR) ............................ 60 Reliability (PD) .......................................................... 62 B

B

Model Selection ........................................................................ 63 3.5.1 3.5.2 3.5.3

Model Input Data………….......................................... 64 Topographic and Geometric Data ................................ 65 Hydraulic Data…............................................................. 65

ix

Table of Contents (Continued)

IV

SIMULATION OF IRRIGATION CANALS (SIC) MODEL.................... 68 4.1

Topographic Module ................................................................. 68 4.1.1 4.1.2 4.1.3 4.1.4 4.1.5

4.2

Description of Hydraulic Network................................... 69 Classification of Reaches............................................... 70 Modification in Topographic Data File ........................... 71 Geometric Computation ................................................. 71 Numerical Results .......................................................... 72

Steady Flow Computations ....................................................... 72 4.2.1 Management and Design Mode..................................... 73 4.2.2 Calibration Mode ............................................................ 73 4.2.3 Calculation of the Parameters........................................ 74

4.3 4.4

Unsteady Flow Computations................................................... 74 Modeling Capabilities................................................................ 75 4.4.1 Computational Processes .............................................. 75

4.5

Steady State Flow Calculations ................................................ 76 4.5.1 Loop Computation.......................................................... 78

4.6 4.7

Unsteady Flow Calculations ..................................................... 78 Cross Structures ....................................................................... 80 4.7.1 Equation at Singular Section.......................................... 81 4.7.2 Regulator........................................................................ 82 4.7.3 Offtakes Equations......................................................... 83

4.8

Performance Indicators............................................................. 84 4.8.1 Volume Indicators .......................................................... 84 4.8.2 Time Indicators............................................................... 86

x

Table of Contents (Continued)

V

RESULTS AND DISCUSSION ............................................................ 88 5.1

Irrigation Management Information System.............................. 88 5.1.1 Cropping Pattern and cropping Intensities ................... 88

5.2 5.3 5.4 5.5 5.6

Relative Water Supply .............................................................. 91 Delivery Performance Ration and Reliability ............................ 96 Crop Yields.............................................................................. 102 Cost Recovery ........................................................................ 103 Actual Strategies for Operation of Irrigation System .............. 105 5.6.1 Current Operation of Chowki Distributary .................... 105

5.7

Calibration and Validation of SIC Model................................. 109 5.7.1 Model Evaluation Statistics (Error Index)..................... 112 5.7.2 Nash-Sutcliff Efficiency Coefficient (NSEC)................. 113 5.7.3 Percent Bias (PBIAS)................................................... 114

5.8

Evaluation of Hydraulic Behaviour of Irrigation System using SIC Model ..................................................................... 115 5.8.1 Flexibility Analysis of Offtakes ..................................... 116

5.9

VI

SIC as Decision Support Tool for Manual Operation Irrigation System .................................................................... 123

SUMMARY, CONCLUSIONS AND RECOMMENDATIONS ............ 128 6.1 6.2 6.3

Summary................................................................................. 128 Conclusions............................................................................. 130 Recommendations .................................................................. 133

REFERENCES ....................................................................................... 134

xi

APPENDICES

Appendix-A Daily Observed Discharges and Statistical Analysis of Discharges................................................. 145 Appendix-B Design Full Supply Level (FSL) and Simulated Water Level at Different Offtakes ........................................... 158 Appendix-C Profile Survey of Distributary and Minors .................... 162

Appendix-D Derivation of Relation Between t-statistics, Root Mean Square Error (RMSE) and Means Biased Error (MBE) .................................................................. 184 Appendix-E Drawing and Figures.................................................... 187

xii

LIST OF TABLES Table

Description

Page

3.1

Salient features of selected distributaries................................. 50

3.2

Head discharge relations of selected distributaries.................. 51

3.3

Frequency analysis of discharges of selected distributaries .... 52

3.4

Climatic data used for determination of evapotranspiration ..... 57

3.5

Procedure developed for determination of sample size .......... 58

3.6

Data of the Chowki Distributary. ............................................... 66

3.7

Data of the Chowki Minor-I and Minor-II................................... 67

5.1

Pre and post IMT annual cropping intensities in the

T

study area ................................................................................. 89 5.2

Monthly average RWS of selected distributaries...................... 96

5.3

Average monthly DPR of selected distributaries .................... 101

5.4

Reliability of irrigation supplies of selected distributaries ....... 102

5.5

Pre and post IMT crop yields of Chowki Distributary.............. 102

5.6

Pre and post IMT crop yields of Pirsabak Distributary .......... 103

5.7

ISF assessed and recovered before IMT ............................... 104

5.8

ISF assessed after IMT........................................................... 105

5.9

ISF recovered after IMT .......................................................... 105

5.10

Manning roughness coefficient used in model calibration .........110

5.11

Calculated values of different statistical parameters for model calibration.....................................................................114

5.12

Calculated values of different statistical parameters for model validation ......................................................................114

5.13

DPR and Eop at different percent of design discharge. ................. 125

xiii

LIST OF FIGURES Fig

Description

Page

2.1

Cubic matrix of irrigation management activities ........................ 12

2.2

Upstream control (Ankum 1993)............................................... 21

2.3

Downstream control (Ankum 1993) .......................................... 22

3.1

Map of Upper Swat Canal (USC) irrigation system .................. 41

3.2

Irrigation management information system .............................. 46

3.3

Observed discharges of Yaqubi Distributary during 2007 ........ 52

3.4.

Observed discharges of Gumbad-II Distributary during 2007 .. 53

3.5

Observed discharges of Qasim-II Distributary during 2007...... 53

3.6

Observed discharges of Toru Distributary during 2007............ 54

3.7

Observed discharges of Pirsabak Distributary during 2007 ..... 54

3.8

Observed discharges of Chowki Distributary during 2007 ....... 55

3.9

Evaporation and rainfall during growing period ........................ 56

4.1

Cross section in a reach (Baume et al. 2003) .......................... 69

4.2

Canal network subdivided into reaches and branches............. 70

4.3

Preissmann four point grid ....................................................... 79

4.4

Weir-orifice cross device .......................................................... 81

4.5

Lateral offtake with a downstream condition. ........................... 83

4.6

Definition of effective volume.................................................... 85

4.7

Definition of time indicator ........................................................ 87

5.1

Relative water supply of Yaqubi Distributary ............................ 92

5.2

Relative water supply of Gumbad-II Distributary ...................... 93

5.3

Relative water supply of Qasim-II Distributary.......................... 93

5.4

Relative water supply of Toru Distributary................................ 94

5.5

Relative water supply of Pirsabak Distributary ......................... 94

5.6

Relative water supply of Chowki Distributary ........................... 95

xiv

Fig

Description

Page

5.7

Delivery performance ratio and CVT(DPR) of Yaqubi Distributary................................................................ 97

5.8

Delivery performance ratio and CVT (DPR) of Gumbad-II Distributary.......................................................... 97

5.9

Delivery performance ratio and CVT (DPR) of Qasim-II Distributary ............................................................. 98

5.10

Delivery performance ratio and CVT (DPR) of Toru Distributary. .................................................................. 98

5.11

Delivery performance ratio and CVT (DPR) of Pirsabak Distributary............................................................. 99

5.12

Delivery performance ratio and CVT (DPR) of Chowki Distributary ............................................................... 99

5.13

Demand and supply pattern of Chowki Distributary ............... 106

5.14

Irrigation water deliveries and ETo at Chowki Distributary..... 108

5.15

Comparison of observed and predicted water levels ............. 111

5.16

Comparison of observed and predicted discharges at offtakes ............................................................ .111

5.17

Proportionality of the open flume outlets (scale: 1:1). ............ 118

5.18

Proportionality of the bifurcator outlets (scale: 1:1) ................ 120

5.19

Proportionality of the trifurcator outlets (scale: 1:1)................ 121

5.20

Spatial variation of delivery performance ratio............................122

5.21

Operational performance under fixed frequency (90-80 percent of design discharge) ....................................... 126

5.22

Operational performance under fixed frequency (90-75 percent of design discharge) ....................................... 126

5.23

Operational performance under fixed frequency (75-85 percent of design discharge) ....................................... 127

B

B

B

B

B

B

B

B

B

B

B

xv

B

Appendix –A A-I

Daily observed discharges at Yaqubi Distributary ................. 145

A-II

Statistical analysis of discharges of Yaqubi Distributary ........ 146

A-III

Daily observed discharges at Gumbad-II Distributary ............ 147

A-IV

Statistical analysis of discharges of Gumbad-II Distributary .. 148

A-V

Daily observed discharges at Qasim-II Distributary ............... 149

A-VI

Statistical analysis of discharges of Qasim-II Distributary...... 150

A-VII Daily observed discharges at Toru Distributary...................... 151 A-VIII Statistical analysis of discharges of Toru Distributary ............ 152 A-IX

Daily observed discharges at Pirsabak Distributary ............... 153

A-X

Statistical analysis of discharges of Pirsabak Distributary ..... 154

A-XI

Daily observed discharges at Chowki Distributary ................. 155

A-XII Statistical analysis of discharges of Chowki Distributary........ 156 A-XIII Crop production estimate for wheat, sugarcane and tobacco per ha. ................................................................ 157 A-XIV Crop production estimate for maize, alfalfa and sugar beet per ha............................................................. 157

Appendix –B B-I

Design full supply level (FSL) at different offtakes ................. 158

B-II

Simulated water level at 110,100 and 90 percent of design discharges ............................................................... 159

B-III

Simulated water level at 80, 70 and 65 percent of design discharges ............................................................... 160

B-IV

Simulated water level at 60 of design discharges ................. 161

xvi

Appendix –C C-I

Profile survey of Chowki Distributary ...................................... 162

C-II

Profile survey of Chowki Minor-I ............................................. 176

C-III

Profile survey of Chowki Minor-II ............................................ 182 Appendix – D

D-1

Derivation of relation between t- statistics, Root Mean Square Error (RMSE) and Means Biased Error (MBE)....................... 184 Appendix -E

E-1

Diagramme and description of Crump’s weir......................... 187

E-2

Detail drawing of single bifurcators. ....................................... 189

E-.3

Section of Crump weir in irrigation network. .......................... 189

E-4

Field test of selected Crump weir. ......................................... 190

E-5

Drawing and description of double bifurcators. ..................... 191

E-6

Irrigation deliveries to Qasim-II, Gumbad-II and Yaqubi Distributaries........................................................ 192

E-7

Irrigation deliveries to Chowki, Toru and Pirsabak Distributaries ..................................................... 192

xvii

LIST OF ABBREVATIONS AOSM

Adjustable Orifice Semi Module (A modified APM)

APM

Adjustable Proportional Module (Crump’s Orifice Outlet)

ASCE

American Society of Civil Engineers

AWB

Area Water Board

BCM

Billion Cubic Meter

CBIO

Crop Based Irrigation Operations

CCA

Cultivable Command Area ( Area served by irrigation canal)

CRBC

Chasma Right Bank Canal System

CV

Coefficient of Variations

DoA

Department of Agriculture

DPR

Delivery Performance Ratio

ETc

Evapotranspiration Coefficient for particular crop

ETo

Reference Crop Evapotranspiration

FAO

Food and Agricultural Organization of the United Nations.

FO

Farmer Organizations. (Management organizations for secondary level)

FSD

Full Supply Delivery

FSL

Full Supply Level (The water level in the parent canal which will allow the intake of a branching canal to pass the full design flow)

FSQ

Full Supply Discharge

GCA

Gross Command Area

GoP

Government of Pakistan

IBIS

Indus Basin Irrigation System

ICID

International Commission for Irrigation and Drainage.

PIPD

Provincial Irrigation and Power Department

IMMI

International Irrigation Management Institute (Now IWMI)

IMIS

Irrigation management Information System

IMT

Irrigation Management Transfer

IWAA

Indus Water Apportionment Accord

IWT

Indus Water Treaty

Kc

Crop Coefficient for calculation of Etc

xviii

LSC

Lower Swat Canal

MAF

Million Acre Foot

MIS

Management Information System

MMH

Minimum Modular Head

NDP

National Drainage Programme

NWFP

North West Frontier Province

OFWM

Onfarm Water Management

O&M

Operation and Maintenance

OF

Open Flume

PHLC

Pehur High Level Canal

PIDA

Provincial Irrigation and Drainage Authority

PIM

Participatory Irrigation Management

RD

Reduced Distance ( Distance from head or intake of canal usually in feet ) 1 RD = 1000 ft (304.8 m).

RWS

Relative Water Supply

SCARP

Salinity Control and Reclamation Project

SCAWB

Swat Canal Area Water Board

SDO

Sub Divisional Officer

SE

Superintending Engineer

USBR

United State Bureau of Reclamation

USC

Upper Swat Canal

WUA

Water Users Associations (Management organization for tertiary level)

XEN

Executive Engineer

xix

GLOSSARY Abiana

Irrigation Water Fee, charged on irrigated and matured crop.

AVIO

The name has the French background, the letter S in the name AVIS has been replaced by the letter O, the letter of the French word “Orifice” to get the name AVIO.

AVIS

The name has the French background, AV are the first two letters of the word ‘aval’ which means downstream, and S is the of the French word, ‘surface’. It illustrate that the gate operates at a free surface flow.

BIVAL Control

Volume control is to have a constant canal volume regardless of the discharge in the down stream canal.

Chak

Tertiary irrigation command.

Control

Structures used on irrigation canals for controlling water level at cross regulators, discharges at head regulators or both.

CROPWAT FAO Computer programme for calculation of crop water requirements. Distributary

Canal taking off from a secondary/branch canal usually supplying water to tertiary/ minor canals or directly to field offtakes.

Duty

Represent the irrigation capacity of a unit of water. It is the relation between the area of the crop irrigated and quantity of irrigation water required during the base period of the growth of the crop and express as 1000 acre per cusec.

ELFLO Control FSL

Predictive Control or pool-end control uses two sensors per regulator.

Full Supply Level (The water level in the parent canal which will allow the intake of a branching canal to pass the full design flow)

xx

Kharif

First season of agricultural year. Summer cropping season from 15th April to 15th October

Level-top Canal

Down stream control requires level-top canal, with horizontal embankments between the regulators to meet the zero flow conditions.

Warabandi

Method of water allocation and distribution. Time is allocated according to landholding size.

Water Allowance

The amount of authorized supplied discharge per 1000 acre of cultivable command area. The water allowance not only determines the size of an outlet structures, but also form the basis for design of distributaries.

Rabi

Second season of agricultural year. Winter cropping season from 15th October to 15th April.

Response Time

The time period between a change in the flow at the upstream end of a canal reach and the arrival of the full modified flow at the down stream end of the reach.

Travel Time

The time period between a change in the flow at the upstream end of the canal reach and the arrival of the first wave (disturbance) at the down stream end. It depends on the factors such as hydraulic of the canal under consideration and the flow rate before and after the changes.

xxi

CONVERSION OF UNITS Length 1m 1 ft 1 ft 1 ft 1 inch 1 inch 1 inch 1 kilometer

= = = = = = = =

3.281 ft 12 inches 30.48 cm 0.304 m 0.025 m 25.4 mm 2.54 cm 0.621 mile

Surface Area 1 ha 1 ha 1 acre

= = =

2.471 acre 10-4 m2 0.4047 ha

Discharge 3 -1

1 ft s (1cusec) 1 m3s-1 (1 cumec) 1 m3s-1 (1 cumec)

= = =

28.32 Ls-1 35.31 ft3s-1 1000 Ls-1

Water Allowance 3 -1

1 ft s per 1000 acre 1 ft3s-1 per 1000 acre 10 ft3s-1 per 1000 acre 10 ft3s-1 per 1000 acre 1 L s-1ha-1

= = = = =

0.665 mm day-1 0.07 L s-1ha-1 6.55 mm day-1 0.77 L s-1ha-1 8.64 mm day-1

Volume 1 MAF 1 m3

=

xxii

1.23 BCM 1000 L

Chapter I INTRODUCTION

1.1

HISTORICAL OVERVIEW

The irrigation system of Pakistan is the largest integrated irrigation network in the world serving approximately 18 million ha of cultivated land. The water of the Indus River and its principal tributaries (the Kabul, the Swat, and Kunar from the West, and the Jehlum, the Chanab, from the East) feed the system. The concept of participation of a farming community in irrigated agriculture in Indo-Pak subcontinent is not new as it has been practiced since time immemorial (Gill 1998). The civil canals in the North West Frontier Province (NWFP) of Pakistan are an example of Participatory Irrigation Management (PIM) and these have been constructed, operated and maintained by the stakeholders since long (1568-1800).

Irrigation development in Pakistan started on a technical foundation in the latter part of 19th century with major objectives to reduce the risk of famine and P

P

maintain political and social stability (Stone 1984). The irrigation system was designed with an objective to optimize the production per unit of available water, ensuring equitable distribution between canals, branches and also among the offtakes (outlets). The duty (area irrigated by unit discharge during the base period) was fixed relatively high in order to irrigate more land with low cropping intensities. Another design objective was to keep the administrative and operational requirements and cost as low as possible and therefore the

1

number of control structures in the canals was kept to a minimum. The irrigation intensity was also kept low at an average of 75 percent. This design practice is known as protective irrigation (Jurriens 1993, Jurriens et al. 1996).

The major constraints to maximize agriculture production in canal commands are due to poor irrigation water management practices. Only 30 to 40 percent of diverted river water to canals ultimately becomes available for the crops (Kahlown and Kemper 2004). Aggregate irrigation water supply does not meet the optimal yield of crops. The time pattern of water supplies is not matched with time pattern of crop water needs. Uncertain and inequitable distribution of supply results in water deficiencies in tail reaches, of canals while upper reaches take excess irrigation supply (Bhutta et al. 1991; Latif and Pomee 2003). In the beginning of the season, farmers have no choice to decide the cropping pattern and cropped area with respect to expected supply in the coming season.

The irrigation system is operated on a continuous schedule at the main system level and at fixed rotational schedule at farm level, the combination of this rigid delivery allows for more economical delivery system operations. The irrigation system consists of a network of alluvial channels. The hydraulic design of a stable alluvial channel requires constant flow at full supply as much as possible. Consequently the outlet normally delivers a constant quantum of supply in the watercourses automatically without any manual regulation. If the flow depth fluctuates, regime of the channel gets seriously upset resulting in

2

silting (for lower discharges) or scouring (for higher discharges). Most of the channels are silted up at the head reaches which makes the distribution inequitable i.e. upper outlets drawing excess discharge and the outlets in the lower portions start suffering. To feed the outlet in the tail reach the canals have to run with extra supply at the head, which further upsets the regime.

The irrigation systems in Pakistan has a number of inherent deficiencies associated with poor operation and maintenance, which need to be improved to bring out put at par with the world's most efficient irrigation systems. Inefficient and ineffective irrigation management leads to a reduction in crop production levels due to a decline in cropped areas and in crop yields per unit area, which are considerably below potential. Due to mismanagement of the irrigation system, a major lesson learned is that government agencies are not effective for managing the irrigation system without involving the farmers.

1.2

RECENT DEVELOPMENT

The Government of Pakistan (GoP) has recently introduced Participatory Irrigation Management (PIM) in the irrigation systems by contraction and reduction of its role and correspondingly expanding the role of water users and other private sector institutions in the process of irrigation management turnover. The turnover process is designed to ensure sustainability of irrigated agriculture, reduce financial burden on government, pass responsibility of operation and maintenance to users, increase water use efficiency, to improve sustainability of the systems. Participation is the core concept used to develop

3

the capacity and capabilities of farmers’ organizations to manage the irrigation systems.

The Pakistan Government has revealed plans to introduce participatory irrigation management (PIM). According to this policy decision, the major canal commands are managed by Area Water Boards (AWBs) controlled by farmers’ organizations (FOs) and Government representatives. These AWBs distribute water to farmers’ organizations (FOs) within that command. At the provincial level, the existing Provincial Irrigation Departments are reconstituted as Frontier Irrigation and Drainage Authorities (FIDAs) providing technical support and supervision to AWBs. The new authorities have greater autonomy from the provincial government, as well as greater accountability to the water users.

1.3

PROBLEM IDENTIFICATION

Operational, maintenance and management aspects of the irrigation system play a pivotal role in overall irrigation management aspects. Without improving this part, no optimal results can be obtained. Improvement and modification to the irrigation systems creates greater flexibility in adapting new modified cropping patterns according to changing market requirements. Flow control of irrigation water is essential for effective irrigation system performance. Efficient operation of an irrigation system requires a constant flow of information between farmer organization, operators, data collectors and overall operation policy makers. Policy makers are interested in the general status of the systems (actual situation versus target) and water availability. Operators require precise and

4

timely instructions on how to operate gates. Farmers want reliable information on water availability and planned allocations so they can effectively plan investments and activities. Field data on rainfall, river and canal flows, actual cropping pattern, etc., should be promptly transmitted and processed for effective use in operation, regulation and management of the irrigation systems.

Presently, the irrigation systems are operated with concern largely for the hydraulic aspects of water conveyance. The surprising characteristics of canal hydraulic operation are the degree of variations that occur daily. Little effort has been taken to improve the operation of the irrigation system and distribution of supplies among distributaries with respect to crop water requirements within available water supply at main canal head. At present irrigation systems face the following chronic problems: •

Lack of effective monitoring and evaluation of water delivery performance to check whether target discharges have been achieved.

•

Insufficient information on the status of gates and control structures to enable operators and managers to determine whether operation plans can be effectively implemented.

•

Lack of farmers’ participation at minor and distributary levels in water distribution and maintenance.

Achieving adequacy, efficiency, reliability and equity of the delivered irrigation water are the main objectives in operation and maintenance of the delivery systems. Poor performance of the irrigation water delivery systems has often been attributed to lack of flow control structures, operation, management and

5

maintenance of the irrigation systems. The objective of this research is therefore to seek ways of addressing these inadequacies through a series of field activities aimed at providing reasonably accurate measured information for assessing performance of recent irrigation management transferred systems to farmers organizations.

1.4

SCOPE OF THE STUDY

In present day context of irrigation management transfer, operation and maintenance has been treated as a central issue, but it is a complex sociotechnical activity which has been inadequately studied and neglected despite evidence that effectiveness to improve the conditions at the tertiary level i.e. below the farmers offtakes (outlet), weakness in the operation of main and distributary level irrigation system has to be rectified. This is the first study in NWFP province by an outside agency on irrigation management turnover (IMT) and operation of irrigation systems by farmers’ organizations.

Many studies in the past have focused on the effect of improved management and institutional developments on irrigation systems performance using multidisciplinary approach e.g. Command Water Management Project (CWMP) and Irrigation System Management Rehabilitation Project (ISMRP). Studies exploring the effect of the relationship between joint operations and irrigation management transfer to farmers’ organizations (FOs) hardly exists. This study investigates the operational problems of the farmers managed irrigation systems and suggests operational procedures for their improvement.

6

The physical (hardware) aspects of the construction of irrigation systems have received intensive attention of Government of NWFP, while the maintenance and management (software) have received very little attention. Maintenance of irrigation network is essential for sustainability of agricultural production. For example, improved irrigation maintenance can make multiple cropping possible and can extend the irrigated area by making more efficient use of available irrigation water. Much evidence exists indicating that improvements in operation and maintenance of irrigation system can lead to substantial and sometimes dramatic improvements in both equity water distribution and production. However, various benefits can be derived from better irrigation management transfer (IMT) of existing irrigation systems.

Finally, it can be argued effectively that, when viewing the irrigation system as whole, increased attention to the operating policies and management plans open the way for major advances in the irrigation system performance. This study is mainly concerned with the operation based on Irrigation Management Information System (IMIS), which impact the irrigation system’s ability to effectively meet the needs of the farmers’ organizations. As the complete irrigation infrastructure are recently constructed, modernized and optimally maintained.

The

maintenance

requirements

presently

(distributary) level are very less, therefore not included in study.

7

at

secondary

1.5

SPECIFIC OBJECTIVES

The objective of the research was to develop a procedure for assessing performance based on the capability and potential of farmers’ organizations using irrigation management information systems (IMIS) and to adopt future strategies to adjust the systems to improve the current performance through hydraulic modeling. Specific objectives of the study were to: 1. Assess the impact of irrigation management transfer (IMT) on the performance of the irrigation system using irrigation management information system (IMIS) techniques. 2. Evaluate the effectiveness of the physical infrastructure with Simulation of Irrigation Canal (SIC) hydrodynamic model. 3. Develop operational strategies using a SIC hydrodynamic model to improve the manual operation of the irrigation system with the assistance of farmers’ organizations (FOs) and Area Water Boards (AWBs).

8

CHAPTER II REVIEW OF LITERATURE

2.1

IRRIGATION MANAGEMENT

Hardware of physical and the software of social structures and organization are the two major inter related aspects of irrigation management. Farmers’ organization (FOs) and Area Water Boards (AWB) cannot succeed without a well designed and well functioning physical irrigation system. Irrigation Management basically refers to all aspects of irrigation beyond the design and construction of facilities. The activities range from the main system down to the farm level, with the middle reaches presenting the most difficult challenges of coordination among the engineers and other technical staff and farmers, who are ultimately managers of irrigation water. Various international agencies agreed that the major problems with the poor functioning of irrigation systems lies in the field of management. Governments, financers and researchers are concentrating on management aspects in the conviction that improvement of management is a major vehicle for improvement of irrigated agriculture. There is a need for some integration of physical, biological, social organizational, administrative, economic and legal factors to achieve system objectives of greater and more certain agricultural production, with more benefits for the participants in the system and for the nation as a whole (Uphoff 1986).

Management of irrigation water requires some essential activities that need to be undertaken; researchers such as Hunt (1989) and Coward (1979) have

9

proposed different classifications of the activities needed to manage water. Irrigation is a socio-technical matter not just because people are involved in the process. Where administration, engineers and technicians play a role in irrigation management, they affect the system performance in many crucial ways, and unless main system management is both effective and responsive, farmers’ efforts to use water effectively will not be fruitful (Wade et al. 1980).

The design of large scale irrigation in South Asia is comprehensive or conventional in which large amounts of water are captured and diverted at a single point from a perennial (large or medium) river. Organizationally, the conventional system design follows a top-down approach (Chamber 1988). In the government agencies mostly centralized public bureaucracy make all decisions with very little pre design or pre construction involvement of farmers. This implies that farmers are least involved in planning, design or construction and operation of system infrastructure. Bottrall (1981) designated management of the main system as a blind spot and considers the delivery of appropriate and reliable supplies at the outlet as a pre condition for proper utilization of irrigation water. Levine (1980) pointed out that shortcomings, commonly attributed to the system design, can some times be overcome by intensive and dedicated system management. Inadequate operation and maintenance have considerably reduced the benefits of large government managed irrigation systems (Svendsen et al., 1983). Researchers (Plusquelle et al. 1994, Plusquelle et al 1996 and Zimbelman 1987) believe that greatest potential for

10

increased agricultural production can be achieved through modernization and by improving irrigation system management.

Focusing on irrigation management leads one view to irrigation not only as a socio technical enterprise but also organizational and managerial, depending on irrigation bureaucracies. While technical personnel are integral to irrigation success, so are the objectives and capabilities of water users. Korten and Uphoff (1981) suggested that government agencies responsible for the management of many irrigation systems needed reorientation. Bureaucracy provides need expertise, skills and organizational capabilities to manage modern technology and public affairs. The distinction between managing systems in contrast to administering is where the decision making is more information based in former and contrastingly more rule based in the latter (Uphoff 1986).

Uphoff (1991) offered a more comprehensive set of water management activities that could be identified in any irrigation system. His cubic matrix shows linkages between the different management activities concerning technology, management, and organization (Fig. 2.1). He proposes three groups of activities namely control structure activities, water use activities and organizational

activities.

Control

structure

activities

include

design,

construction, operation and maintenance. Water use activities include water acquisition, allocation, distribution and drainage.

11

Fig. 2.1 Cubic matrix of irrigation management activities (Uphoff 1991).

To classify these activities, processes of conflict management, communication, resource mobilization and decision making are required. Acquiring irrigation supplies from barrages and weirs is considered socio-technical because decision-making,

resource

mobilization,

communication

and

conflict

management are intimately associated with the physical structures and resource flows.

2.2

DESIGN AND MANAGEMENT INTERACTION

Technology has great implications on the availability of irrigation deliveries at different points within an irrigation system as is emphasized by many researchers including Horst (1990), Lankford and Gowing (1996) and Levine

12

(1980). The attention for the relation between design and management is now growing. Every design puts its requirements and restriction on the management.

Management

must

be

organized

around

the

physical

components of the systems, which are specified by design. A number of typologies exist to describe irrigation infrastructure and systems of water control to deliver irrigation supplies according to different water distribution schedules and objectives (Plusquellec 2002). Levine (1980) emphasized the relationship between the design, operation and maintenance of irrigation systems through water and crops. The objective of the system, like equitable water distribution, or supply of adequate water for the pre-defined cropping patterns, defines the choice of the technology to distribute water.

Horst (1998) recognized the link between design and management by raising the question of whether it would be possible to design irrigation systems keeping in view the human and institutional aspects and, if so, what the consequence on the type of technology would be? He described different irrigation water delivery systems and their implications on water delivery. His research focuses on water division structures and how their operation can lead to dysfunctionality. He regards irrigation structures as technical artifacts and calls for transparent technology whose operation and significance can be understood. He states that division of water is not only a technical matter, but it also has a human dimension. The way farmers perceive these technical artifacts may cause conflicts between the farmers if they are not satisfied with the flow rate, duration and frequency of irrigation supply. These conflicts may

13

result in the farmers' intervention by damaging the structures and in the operation of the system. He suggests for transparent technology that should include general consensus by the farmers and agency on the allocation and distribution of water; and a system of canals and structures which enables farmers to understand the flows of water by their own perception.

2.3

IRRIGATION MANAGEMENT INFORMATION SYSTEM (IMIS)

Irrigation management information system (IMIS) is as an organized method of providing past, present and projected information relating to internal operations and external intelligence. It supports planning control and operation functions of an organization by furnishing uniform information in the proper time frame to assess the decision-making. IMIS supports the planning, control and operational functions of organizations. In this sense, an IMIS performs three functions i.e. accept data input. These data come from internal and external sources, or both. Second IMIS acts on data to convert it into information, and third IMIS produces information for managers.

The need for introducing IMIS in the day-to-day operation and management of an irrigation system has been emphasized by many researchers (Rey and Hemakumara 1994; Jain 1995). It is recognized widely that effective IMIS is critical to an organization’s success. IMIS serves as a conduit through which managers understand their firms’ external environments and develop internal relationships and structures necessary to reach and implement decisions that will allow their organization to achieve success.

14

The definition of suitable operations policy of an irrigation system assumes an increasing relevance in the context of growing scarcity and competing uses of water. Simulation models and decision support systems (DSS) can play an important role in the defining of an operational plan that must be easily accessible to all the stakeholders. Many IMIS and DSS are developed by researchers but are site specific in nature. Bazzani and Rosseli (2002) developed a DSS for agricultural irrigation and economic environmental assessment. Gao (2004) developed decision making support systems to improve water management in pumped irrigation systems in China. The decision making is based on the application of computer networks and specially developed programmes. Significant technical benefits have been achieved through the use of DSS.

2.4

IRRIGATION MANAGEMENT TRANSFER

Due to mismanagement of irrigation systems, major lessons learned are that government agencies are not effective for managing the irrigation systems without involving the farmers. There exists farmer managed irrigation systems covering thousands of hectares in Colombia, Argentina, Mexico and even in Nepal. The government agencies continue to operate the dams and regulate the river flows while the operation, maintenance and water distribution lies with the farmers. In the Philippines, involvement of farmers in planning, design and construction of irrigation systems promotes farmers satisfaction with physical facilities, and is a useful way to strengthen irrigation organizations, which then can become the managers of the new or improved systems. Further, the effort

15

to strengthen farmers’ organizations and management transfer resulted in staff reduction, enhanced fee collection, and the agency was able to meet full operational expenses, including pay of their staff (Meinzen-Dick et al. 1995).

Vermillion (2001) and Svendsen and Meinzen-Dick (1997) termed the current period as the reform era that is characterized by efforts to modify the basic policies and institutional reforms to manage the irrigation systems by employing the irrigation management transfer (IMT) approach. Levine et al. (1998) assessed the achievement of water users in managing water allocations and deliveries in Mexico. Results indicate that the joint management by the water users has been reasonably successful in implementing water allocation and cropping plans. Vermillion and Garcés (1996) reported that in Colombia, the government adopted a national devolution policy as part of its general strategy of economic liberalization and political decentralization and management transfer encouraged a number of managerial changes expected to improve management efficiency and accountability of staff.

IMT resulted in a significant change in the burden of cost from the government to farmers. Most of the cases; it has been accepted by the farmers. It is observed by many researchers (Bandaragod and Memon, 1997; Bandaragoda 1999; Brewer et al. 1999) that transfer has not had significant impacts on the performance of operations and maintenance, or on the agricultural and economic productivity of irrigated land. However, the research shows that rural

16

poor often get additional responsibility and costs from IMT rather than benefits and authority to participate in decision making.

In Mexico under IMT, the water rights are transferred from government to water users associations. Similarly in Sri Lanka and the Philippines, water users are given partial management responsibilities, such as water delivery, canal maintenance and paying for irrigation service charges. If executed with sustaining policies and programs, IMT can play a significant role in poverty alleviation. Farmers are agreeable to pay irrigation service fees (ISF) only the benefits outweigh the costs (Hassan 2002). It is also recognized that IMT can be successful only if the rural population benefits from this reform and if the rural farmers are capable to finance irrigation. Furthermore, the future performance of irrigation infrastructure largely depends on proper maintenance. Due to insufficient cost recovery to maintain the irrigation infrastructure, the performance of irrigation systems will deteriorate and the rural poor will not receive water, required for their food security, On the other hand, if ISF is increased, then the irrigation costs could be double or triple for the rural poor who already hardly earn any income within the given context (Bhata 1997; Dinar and Subramanian 1997, Hussain

2007) concluded that although

irrigation management transfer and participatory irrigation management have generated some benefits to the poor, these have been implemented partially, with no explicit pro poor elements.

17

2.5

MODERNIZATION OF IRRIGATION SYSTEMS

Modernization of the irrigation systems is recognized as an essential transformation in the management of irrigation systems contained by agricultural areas. Such transformations may comprise improved structures, physical or institutional or both; rules and water rights; water delivery services; accountability mechanisms and incentives (Molden and Makin 1997).

Burt and Styles (1999) defined Irrigation modernization as a process of technical and managerial upgrading (as opposed to mere rehabilitation) of irrigation systems combined with institutional reforms, if required, with the objective to improve resource utilization and water delivery service to farms. Modernization of irrigation systems virtually always involves modification of three things (Plusquellec 2002). •

Everyone in the systems, from the lowest operator to the highest administrator, must adopt the concept of providing good service. This requires that they understand the service concept, and truly have a desire to provide as high a level of service to their customers as is possible.

•

Hardware must be modified in order to provide better service. The hardware changes are the result of a deliberate analysis of service requirements. Hardware modifications may be as simple as replacing undershot gates (orifices) with manual long crested overshot gates (weirs) for water level control, or the proper installation of flow control points. In some cases, it may require more advanced supervisory control and data acquisition (SCADA) systems and automation. The desired level of water delivery service, existing budget and other constraints will define the required hardware, and not vice versa.

•

Operation rules delivered, the operators and personnel), and

must be changed. The way that water is ordered and form and frequency of communications (between their bosses, and between farmers and systems the way various control structures are manipulated on

18

an hourly or daily basis must be changed to match the defined service objectives.

2.6

FLOW CONTROL IN IRRIGATION SYSTEMS

A great deal of practical and theoretical work has been conducted on the control and automation of canal systems. The various concepts of canal control have been well summarized in the literature by several authors (Clemmens 1979; Clemmens and Replogle 1989; Ankum 2004). Additional details concerning existing technologies have been reported by ASCE Task Committee on Irrigation Canal System (1993).

2.6.1 Canal Control Methods The most important kind of canal control methods are proportional flow control, which is the most simple flow control method and has to be selected when an irrigation main system does not require any management of the flow diversion. Downstream control is considered to be flexible and demand-oriented whereas upstream control is associated with rigid top-down water delivery. Fixed upstream control (proportional distribution) is technologically simple in operation and maintenance. Responsive centralized control, necessitate sophisticated computer equipment, standard maintenance, skilled operators, and is likely to produce significant levels of risk due to equipment failure.

Volume control in irrigation was developed by Sogreah of France under the name called BIVAL control. Volume control solves the problems of too large

19

storage wedge in traditional downstream control. Volume control is often recommended

at

new

steep

slopping

canals,

requires

simultaneous

measurement of the water level at the head-end and the tail end of the canal section to respond immediately to downstream demand (Ankum 2004). In 1967 the USBR developed an analog proportional controller using hydraulic filter level offset method. It was replaced by improved electronic filter (ELFLO) to produce self management flow control on sloping canals, where downstream control would not be applicable because of the steep canal gradient (Ankum 1994). CARDD control (Canal Automation for Rapid Demand Deliveries) was developed for regulation on the sloping canals by automatic downstream control and measure three water levels per canal section (Burt 1987). Mixed control, also called combined control may behave as an upstream or downstream control system, depending on the water level in the canal section. Its regulators have set-points at the upstream water level, as well as downstream water level (Ankum 2004).

Downstream controlled systems are normally equipped with hydro-mechanical gates, such as AVIS and AVIO gates have been developed by Neyrpic and are commercially manufactured by Alstom Water Systems. AVIO and AVIS gates operate in response to changes in the downstream water level. The difference between AVIS and AVIO gates is that AVIS gates operate at free surface flow in the upstream canal sections, while the AVIO gate closes the orifice. The AVIO is suited to control flow from a reservoir through an orifice opening. The AVIO and AVIS gates have a large float immediately downstream from the

20

radial gate pivot arm. When the downstream water level rises, the float rises and the gate closes (Ankum 2004).

2.6.2 Upstream Control Upstream control is a control technique in which a water level regulator maintains a constant upstream water level at the regulator and maintains target water levels for any discharge. Main systems under upstream control perform quite unsatisfactory and introduce many operational problems (Ankum 1993). Upstream control deserves its popularity because of the of the supply-based control concept, where the irrigation agencies determine the amount of water released to the tertiary canal. The performance of a tail-end regulator (R2) in B

B

Fig. 2.2 illustrates the operational problems. The intended discharge at (R2) is B

B

initially available from the ponded canal, but will drop immediately with falling head in the canal. The effect of the upstream release will be felt only when the disturbance will arrive at (R2). The new steady-state is reached after the canal B

B

storage is filled (Ankum 1993).

Fig. 2.2 Upstream control (Ankum 1993).

21

2.6.3 Downstream Control Downstream control is a control technique in which the water level regulators respond to the conditions in the down stream canal reach and is self system management and do not require water operators. Downstream control solves the problems of response time and operational losses. Downstream control is based on a demand-based control concept. Formers organizations can determine the amount of water released at any time and water is available for instant distribution. The regulators in the main canal maintain a constant water level at the downstream side of the structure without regarding discharges. Such regulation means more supply is given to the canal reach when the water level drops. The effect of discharge at each regulator is automatically adjusted to accommodate downstream demand for irrigation water (Fig. 2.3).

Fig. 2.3 Downstream control (Ankum 1993). Downstream control requires level-top canals with horizontal embankments between the regulators to meet the zero flow conditions (Fig. 2.3). An aspect of

22

downstream control with level-top canals is the criterion of the positive storage wedge in the canal reaches, i.e. volume of water between the segment water level (level-top) and lower full-flow water level. This leads two main advances of the downstream control methods (Ankum 2004):

2.7

‰

irrigation water can be supplied immediately at the desired discharge, as it is available from the in-canal storage.

‰

irrigation water is not wasted as a result of difference between supply and demand, as this difference is stored in the in-canal storage.

PERFORMANCE ASSESSMENT

The performance assessment concept is essential to successful management of an irrigation system. The ultimate purpose of performance assessment is to achieve efficient and effective irrigation performance by providing related feedback to management at all levels. As such, it may assist management or policy makers in determining whether performance is satisfactory and, if not, which corrective actions need to be taken in order to remedy the situation. The performance assessment of irrigation systems can be broadly categorized as (Bos et al. 2005): •

Operational assessment provides system managers with information to enable them to manage and operate the system.

•

Accountability assessment provides information to assess performance of those responsible for the systems's performance.

•

Intervention assessment is undertaken to determine how to improve some aspects of the system’s performance.

•

Sustainability assessment enables planners to assess the long term viability of a system.

23

the

Performance assessment is key factor to improve daily operation, to diagnose problems and monitor the effect of interventions to solve these problems. With scarce water resources, the need for better performance of irrigation became obvious. For an effective performance assessment programme a framework need to be define. It is helpful to consider an irrigation system in the context of nested systems to describe different types, uses of performance indicators and address the important question of boundaries within which performance is assessed (Small and Svendsen 1992). In this study the authors reported that, the performance of irrigation water delivery systems and performance of irrigated agriculture systems relies on the water conveyed by specific set of canals. It is reasonable to assess the performance of Area Water Boards and Farmers Organizations in terms of water delivery performance criteria like reliability and equity.

Many engineers and researchers (Bos and Nugteren 1990, Levine 1982, Abernethy 1986; Oad and McCornick 1989, Molden and Gates 1990, Murray Rust and Snellen 1993; Merrey et al. 1994, Bos 1997, Malano and Burton 2001 and Bos et al. 2005) have tried to standardize performance indicators to permit better comparison of irrigation systems. To assess the performance it is important to confirm the indicators selected in respect to the objectives established for that irrigation system. A good indicator tells a manager what current performance of the system is, and, in combination with other indicators, may help to identify the correct course of action to improve performance within that system. The indicator should be empirically quantified and statistically

24

tested. Discrepancies between the empirical and theoretical basis of the indicator must not be hidden by the format of the indicator. It must be understood readily by all participants and the cost of measuring it regularly must not be excessive.

Gorantiwar and Smout (2005) described two types of performance measures i.e. the allocative type comprising productivity and equity; and the scheduling type comprising adequacy, reliability, flexibility, sustainability and efficiency. The methodologies to estimate these measures are explained by (Makin et al 1991; Latif et al. 1994; Goldsmith and Makin 1991) and provide the irrigation authorities with information on the performance of irrigation management in the system, their management capability to the response of variations in climatological, physical and management aspects and insight to improve the performance during different phases of irrigation water management. Indicators which focus on the process of operating a system and break down of this process into management and system components have been defined by Molden and Gates (1991). The objective of using comparative indicators is to evaluate outputs and impacts of intervention in individual systems, compare performance of a system over time, and also to allow comparison of systems in different areas and at different system levels (Molden et al. 1998).

The productivity is relevant when the outputs are measured in terms of whichever input is scarce. Lenton (1986), Chambers (1988), Abernethy (1989)

25

listed various indicators of productivity. The productivity indicators are easy to quantify and included in all studies related to performance of an irrigation systems.

The sustainability indicators enable the irrigation authorities to know which management strategy is more sustainable or environmentally friendly (Gorantiwar and Smout 2005). Sustainability is the performance measure related to upgrading, maintaining and degrading the environment in the irrigation system. According to Abernethy (1986), sustainability is the most difficult factor to encompass and refers to the issue of leaching, drainage and salinization which if not attended properly, may shorten the system’s life.

The success of irrigation water management in the irrigation systems depends on appropriateness of all these processes. Generally, process indicators are used to assess actual irrigation performance relative to system-specific management goals and operational targets. It is believed that, in comparison with process indicators, the application of comparative indicators requires data collection procedures that are less time and resource-consuming (Kloezen and Garcés-Restrepo 1998). Indicators which focus on the process of operating a system and break down the process into management and system components have been defined by Molden and Gates (1991).

Irrigation delivery service, performance and control are primarily linked. Renault (1999) developed analytical relationships between the controls of canal water

26

depth, and the sensitivity of irrigation delivery structures. Renault and Hemakumara (1999) attempted to develop an analytical framework to address sensitivity of irrigation off takes. Sensitivity of delivery takes into account the impacts of the perturbations on the delivery to the command area of the offtake. P

Renault et al. (2001) observed that, the flow behaviour along canal irrigation network can be assessed by determining the sensitivity of the irrigation structures. The importance of governing factors of the sensitivity and proportionality indicators are analyzed using a theoretical approach as well as practical results from historical data on a gated system in Sri Lanka and structured system in Pakistan. They recommended that the sensitivity indicator be determined for the full supply depth in the parent canal and the maximum discharge through the offtake.

2.8

MODELING NEEDS IN WATER MANAGEMENT

Fast developments have been made in the development of computer models and their applications to irrigation systems during recent years. In the fields of irrigation and drainage, modeling has the potential for improvement in planning, design, operation and management. Modeling and simulation play an increasing role in enhancing the operational performance of irrigation systems.

A program called Gate Stroking is used in unsteady flow modeling to determine gate setting systems. The usual procedure for unsteady flow modeling is to determine flow rates and water levels from known boundary conditions and

27

gate settings. Gate stroking reverses this procedure and calculates gate openings to achieve desired water levels and flows in the system. Specifically, the program attempts to provide constant water levels upstream from each check structure so that a flow rate to offtakes remains constant (Falvey and Luning; 1979). The main applications envisioned for unsteady flow models are: analysis of the system characteristics; and the development and testing of operational plans, control strategies, and control algorithms.

2.9

HYDRAULIC MODELING SOFTWARE

There is a wide variety of canal flow simulation programs that deal with the different types of flow in open channels. The main differences between those programs can be seen as the size of the irrigation network that can be simulated in one run, and the types of flow that a program can solve. Some programs can solve the uniform flow type only, while others can solve both the uniform and the unsteady flow types. There have been many applications of hydraulic models for the analysis of canal system performance under proposed operation, management delivery and schedules (Islam et al. 2008, Mishra et al. 2001, Gichuki et al. 1990; Merkley et at. 1990; Swain and Chin 1990). Unsteady flow models can employ several solution methods of varying degrees of sophistication (Hamilton and DeVries 1986), and with different levels of accuracy and robustness. Hydraulic simulation models that can handle both steady and unsteady flow are reviewed below. The models are listed in alphabetical order.

28

2.9.1 Branch-Network Dynamic Flow Model (BRANCH) BRANCH developed by United States Geological Survey (USGS) is hydrologic analysis software used to simulate steady or unsteady flow in a single openchannel connected in a looped pattern. It is applicable to a wide range of hydrologic situations wherein flow and transport are governed by timedependent forcing functions. BRANCH is suitable for simulation of flow in complex geometric configurations and having multiple interconnections, but can be easily used to simulate flow in a single, uniform open-channel reach. Time varying water levels, flow discharges, velocities, and volumes can be computed at any location within the open-channel network. Stream flow routing and computation by the BRANCH model is superior to simplified-routing methods in open channel reaches.

The BRANCH model uses a weighted four-point, implicit, finite-difference approximation of the unsteady flow equations. Flow equations are formulated, using water level and discharge as dependent variables, to account for nonuniform velocity distributions through the momentum Boussinesq coefficient, to accommodate flow storage and conveyance separation to treat pressure differentials due to density variations and to include wind shear as a forcing function.

2.9.2 Canal Management (CANALMAN) CANALMAN developed by the Department of Biological and Irrigation Engineering, Utah State University, USA, is a hydraulic model to simulate

29

unsteady flow in branching canal systems with trapezoidal cross sections. Canal reaches are separated by inline structures such as gates, weirs, etc.

CANALMAN uses an implicit solution technique to solve the complete Saint Venant equations (Gichuki et al. 1990; Merkley et at. 1990). The simulation time step can be varied from one to ten minutes. CANALMAN will simulate the topology of most canal systems, including branch canals. A maximum of four branches, with a total maximum of 40 reaches, can be simulated with a single model set up. Channel friction gradients are computed using Manning's equation. Boundary condition analysis in the model is of average accuracy.

A unique and valuable feature in CANALMAN is its capability to analyze water advance on a dry bed, which is a problem for most other simulation software. Initial filling of an empty canal can be studied with reasonable accuracy, which should be particularly valuable to operators of small canals and laterals that are frequently drained and filled. On the other hand, the program will not analyze channel dewatering, rapid flow changes, negative flow at structures, hydraulic jumps, and supercritical flow (Merkley and Rogers 1993). CANALMAN model was used for operation and management of the Kangsabati irrigation project (Kumar et al., 2001).

2.9.3 CAlcul des Riveres MAilles (CARIMA) CARIMA (SOGREAH Consulting Engineers, Grenoble, France) Although CARIMA was originally developed for flood propagation studies; it has been

30

used for regulation problems in irrigation canal systems. The program solves the complete de Saint Venant equations with the unconditionally stable, convergent Preissmann method to analyze unsteady flow conditions. The nonlinear algebraic equations resulting from application of the Preissmann methods are solved in a Newton-Raphson context. The initial conditions required for starting any simulation run can be taken from the results of a previous run, calculated by CARIMA using an automatic steady flow stabilization procedure, or directly entered by the user. A zero discharge initial condition is perfectly admissible; however, a zero depth condition (dry bed) cannot be accommodated.

CARIMA routinely treats simple, branched, or looped systems, including interconnected floodplain cells. Channel sections can be trapezoidal, circular, or general (defined by either elevation and width or distance from bank and elevation). CARIMA uses the Manning or Chezy equations. The resistance coefficient can be specified as constant within an entire cross section or within a subsection. The different types of external and internal boundary conditions supported by CARIMA are: discharge hydrographs, stage hydrographs, rating curves, pumps, composite rectangular weirs, composite rectangular gates, local head loss, storage basins, culverts, inclined weirs, idealized flood control dams, and automatic regulators. However, it contains no specific treatment of hydraulic jumps or bores, and cannot normally accommodate dry bed situations. This currently under development (Holly and Parrish 1991).

31

2.9.4 Dutch Flow (DUFLOW) DUFLOW (The Tidal Water Division; Delft University, The International Institute for Hydraulic and Environmental Engineering, The Netherlands) , is a userorientated package for unsteady flow computations in networks of open watercourses. Apart from uniform and non-uniform flow calculations, it can address, for example, propagation of tidal waves in estuaries, flood waves in rivers and operation of irrigation and drainage systems. Free flow in open channels is simulated and control structures like weirs, culverts, siphons, and pumps can be included. A simple rainfall runoff relationship is part of the model. DUFLOW can be used for large river systems, but also for simpler irrigation and drainage networks, for which input hydrographs can be specified. A fourpoint implicit Preissmann scheme is used to solve the complete Saint Venant equations of continuity and momentum. The user can select solutions of linearized or fully nonlinear versions of the equations. The latter being solved with a Newton-Raphson type scheme that starts from the linearized results. DUFLOW does not include a separate steady-flow solution procedure and uses the unsteady procedure to handle both types of flow. Cross sections are defined at each node in terms of top width of flow at given depths. The Chezy equation is used as the standard frictional resistance equation for channels, culverts, and siphons. The Manning-Strickler equation can be used for channel resistance. DUFLOW has the capability of adding wind shear, which can be applied in any direction relative to the channel reach.

DUFLOW has some limitations in modeling canal networks. The maximum number of channel sections and structures in a model is 250. Cross sections

32

can be defined with up to 15 depth-width pairs. DUFLOW cannot simulate critical flow, hydraulic jumps, and dry-bed channels. It cannot model automatic canal gate control mechanisms, but it is a menu driven program. It is public domain software and is distributed at a nominal cost (Clemmens et al. 1991).

2.9.5 Modeling Drainage and Irrigation System (MODIS) MODIS (Delft University of Technology, The Netherlands) is an implicit hydrodynamic modeling package that computes the unsteady water flow in open channels. Branched and looped open channel networks can be modeled by the program. The simulation of structure operational plans and control are easy to perform in MODIS. Furthermore the model has performance indicators that allow for a fast diagnostic interpretation of the results. The MODIS model can run in various computational modes, varying from steady state mode to full dynamic mode, in which the complete Saint Venant equations are solved. The applied numerical solution technique is based on finite differences using the four point Preissmann implicit scheme. The friction term of the Saint Venant equations is represented by the Manning-Strickler resistance formula. Real time controlled canals can be simulated in MODIS. Several control algorithms are standard in the model: multiple speed control, proportional-integraldifferential (PID) control, CARDD, BIVAL, and EL-FLO controls. To avoid program termination in case of dry-bed flow, a Preissmann slot is automatically added to trapezoidal cross sections. A sub routine prevents the slot from falling dry by continuously checking the water levels. (Schuurmans 1993).

33

2.9.6 Simulation of irrigation Canals (SIC) SIC (CEMAGREF, France) provides a detailed simulation of flow in a canal system and thus allows for studies, for example, to reduce water losses and inequity of supply to users. The model is based on one-dimensional hydraulic analyses for transitional and steady-state flows. It is divided into three parts: a topographical unit to generate the topography and topology of the scheme, and two separate computational units for steady and unsteady flow. Special features include a calibration module to compute both Manning's and discharge coefficients, given measured flows and water levels.

It is also possible, for example, to calculate structure settings to achieve the required flow at offtakes and proportion of flow in the canal. Seepage and inflows can also be taken into account. But it cannot be applied in the cases of supercritical flow and dry beds (Baume et al. 2005). The SIC model is extensively used in Pakistan, Punjab (Waijjen et al. 1997), Sindh (Lashari et al. 1999) and especially in NWFP for design of Chashma Right Bank Canal Habib et al. (1999) and Pehure High Level Canal to examine the hydraulic and operational behavior Habib et al. (1996).

2.9.7 Unsteady Model (USM) USM (US Bureau of Reclamation, Denver, USA) is hydraulic simulation software that models gradually varied unsteady flow in canal systems. The primary purpose and application of the program has been the hydraulic analysis during the design of new canals and canal control systems. USM uses

34

the method of characteristics to calculate a numerical solution to the complete Saint Venant equations of unsteady open channel flow. Two solution methods are available: complete grid of characteristics and specified time interval. In the first solution, the calculation time step varies as water depth and wave speed change. The specified time interval solution uses a fixed time step. The method of characteristics yields an accurate numerical solution, but requires a large number of computations since the calculation time step must be small. Therefore USM is more efficient for solving problems of short duration involving rapid flow changes than for problems of long duration with gradual changes (Rogers and Merkley 1993).

USM topology is limited to a linear series of up to 40 canal pools separated by structures or boundary conditions. Branching or looping cannot be modeled directly. The program can model trapezoidal, rectangular, circular, U-shaped, trapezoidal with one vertical side, and trapezoidal membrane-lined sections. Different values of cross section, roughness, slope, etc., may be entered for each canal pool, but they are assumed to be constant for each pool. Computational nodes are spaced in equal user defined intervals within a pool. USM does not simulate advance on a dry bed, canal dewatering, hydraulic jumps, bore waves, supercritical, flow, or negative flow through structures. The maximum time span for a single simulation is 24 hours (McGarry 1990).

2.9.8 ISIS Flow ISIS Flow (Sir William Halcrow and Partners Ltd, Hydraulics Research Wallingford Ltd UK) is a computer program used for modeling steady and

35

unsteady flows in open channels and flood plains. Any sensible looped or branched open channel network can be modeled using the program. The program is modular and the channel network is modeled by breaking it down into hydraulic components referred to as units. ISIS Flow contains units to represent a wide variety of hydraulic structures including several types of sluices and weirs, side spills and head losses through bridges. Closed conduits and culverts are represented by cross sections and several standard shapes are available. Other units include reservoirs (to represent flood storage areas, for example) and junctions. Free surface (flow depths and discharges) is computed using a method based on the equations for shallow water waves in open channels. Two methods are available for computation of steady flow problems: the direct method and the pseudo time stepping Method. In ISIS Flow, the model external boundaries are represented as either flow-time, stage time or stage flow (rating curve) relationships including specifying tide curves and hydrological boundaries.

A special hydraulic feature in ISIS Flow is its capability on modeling supercritical flow. This is achieved by neglecting the part of the convective momentum term in the momentum equation when the Froude number exceeds a specified upper value. Also ISIS Flow can relatively cope with dry bed situations by introducing a minimum water depth when the depth approaches zero. ISIS Flow solves the differential form of the momentum equation, the solution at a hydraulic jump or bore can never be accurate. Instead of a sharp change in stage, the change will be smeared over several nodes.

36

2.10

COMPARISON OF IRRIGATION SIMULATION MODELS

The review of hydraulic modeling software presented above illustrates a great variety of models which cover a wide spectrum of features and capabilities that indeed emphasize the importance of such modeling tool in the study and design of irrigation systems. Some points of interest to highlight are: some models like CARIMA and ISIS were originally designed for flood routing and river modeling. Later they modified to include the ability of irrigation networks analysis. The rest of the reviewed models were specifically designed to model irrigation networks except BRANCH which is suitable for river modeling only as it cannot model irrigation structures.

Many models were designed to satisfy particular needs in the design and operation of irrigation networks: CANALMAN is mainly concerned about the management of irrigation systems and excels in the analysis of canal filling procedures. USM was designed to focus on the analysis of emergency operations of newly designed canal structures. ISIS Flow includes a large builtin structure library. MODIS targets controlled irrigation canals with its capability of duplicating most manual and automatic structure operations besides calculation of some performance indicators that helps in monitoring system performance.

All the reviewed models solve the complete Saint Venant equations for unsteady flow calculations. The four-point Preissmann implicit scheme is used for solving the equations in all the models except USM where the method of

37

characteristics is used. The four-point Preissmann implicit scheme is usually more robust and can cope with more varied hydraulic conditions at the expenses of accuracy, while the method of characteristics achieves the opposite. It is interesting to notice though that most of the models reviewed have almost the same limitations in their modeling capabilities: supercritical flow cannot be handled (except ISIS); zero water levels (dry beds) cannot be solved (except CANAlMAN and MODIS); canal dewatering cannot be simulated; hydraulic jumps and bore waves cannot be simulated.

Mishra et al.

(2001) applied MIKE 11 to improve the operation and

management of Kangsabati project, India. Shahrokhnia et al. (2005) used HECRAS model to evaluate the performance of Doroodzan irrigation network in Iran.

From aforementioned review it appears that hydraulic models are

appropriate tools, if properly calibrated and validated to understand and diagnose the hydraulic behaviour of the irrigation system and consequently can be utilized to improve the operational performance of the irrigation systems.

38

Chapter III Material and Methods

3.1

UPPER SWAT CANAL IRRIGATION SYSTEM

The Upper Swat canal (USC) irrigation system was commissioned in 1914 that irrigates a large proportion of the fertile Peshawar Valley. The Upper Swat Canal (USC), which takes water from Swat River through Amandara head works, was originally designed for a discharge of 68.6 m3s-1 (2420 cusecs) to P

P

P

P

irrigate an area of 127,500 hectares (315,000 acres) of Charsadda, Mardan, Swabi and parts of Malakand Agency plains (Fig. 3.1). The canal, after traversing the narrow ridge of Malakand hills through the Benton Tunnel, eventually bifurcates at Dargai into two branches of Machai Branch at left and Abazai Branch at right side. After the construction of the Benton Tunnel, it was realized that, though constructed to the full design section, its discharge capacity was not more than 51 m3s-1 (1800 cusecs) due to its unlined and P

P

P

P

rough surface. As a result of this constraint, the authorized full supply discharge of the canal was fixed at 51 m3s-1 (1800 cusecs) and the cultivable command P

P

P

P

area (CCA) reduced to 111,700 hectares (276,000 acres).

To bridge the gap of water shortages, an auxiliary tunnel was designed and constructed for a discharge of 51 m3s-1 (1800 cusecs). P

P

P

P

As a result of the

construction of this tunnel the capacity of the Upper Swat Canal (USC) was also increased up to 100 m3s-1 (3531.50 cusecs). About 75 km length of the P

P

P

P

39

Upper Swat Canal (RD 0+ 000 to 242 + 000) was rehabilitated under the Swabi Salinity Control and Reclamation Project (Swabi SCARP Project) in 1998, while the remaining portion of about 50 km was remodeled under the Pehur High Level Canal (PHLC) Project in 2002. Rehabilitation and modernization of the USC permitted more irrigation development in the upper reaches of the canal. The water allowance was increased from 0.39 Ls-1ha-1 to 0.77 Ls-1ha-1. The P

P

USC is operated under upstream control, in which adjustments to canal discharge are made at the head of the main canal system. Response time near the tail of the canal system is typically 4-5 days. The flow is continuous into the head of the system, and split in proportional to the command area into the distributaries (secondary) canals. Tertiary canals offtakes (outlets) flow continuously and each serving a command area typically between 50 to 250 ha.

3.1.1 Pehur High Level Canal (PHLC) Pehur High Level Canal was constructed during 1997. It is 26.2 km long having majority of its length as lined channel. Secondly the Maira branch obtains irrigation supplies from the PHLC at confluence point of RD 242+ 000. The PHLC provides supply to Maira Branch with gross water allocation of 0.645 BCM from Tarbela reservoir. The canal is designed and constructed with a capacity of 28.30 m3s-1 (1000 cusecs). P

P

P

P

40

Fig. 3.1 Map of Upper Swat Canal (USC) irrigation systems.

41

Regulation of the PHLC and the tail of the combined system in Maira Branch are achieved through downstream control. Water is stored in the PHLC and Maira Branch in ponded reaches. The points of control are hence shifted to the distributary head regulators. When more or less water is required in the distributary, the head regulator gate is adjusted accordingly and no water is wasted as it retained within the main canal. The tail of the canal system also receives the designed water supplies. This is achieved through self-regulating float operated cross regulator (AVIS and AVIO type) gates that are installed at about 5 km intervals. These gates are sensitive to water level and open and close automatically in order to maintain downstream water levels. This effect is carried up through the system to Tarbela Dam, where a control system SCADA (supervisory control and data acquisition) operates the Gandaf Outlet valves (Fig. 3.1) in response to water levels in the PHLC head reach (Bozakov and Laycock 1997; Laycock et al. 2005).

The water distribution at the distributary level is regulated through manual operated undershot sliding gates traditionally. In order to facilitate their operation and monitoring the irrigation supply, Crump’s weirs are installed in the head reaches of the distributaries. Proportional dividers (bifurcators and trifurcators) are Crump’s weir with splitter wall to divide the flow in proportion to the irrigated area served by each offtake and the downstream parent channel. The Crump’s weir (Bos 1989; Herschy 2009) has an upstream face sloping at 1:2 and downstream face slope 1:3. For large structure with discharge greater

42

than 5 m3s-1 the downstream face slope is 1:5. The minimum width of any offtake is 0.15 m. The width of the offtake channel is adjusted by increasing or decreasing the length of weir crest. Proportional divisors are used where the smallest offtake discharge is not less than 10 percent of the incoming parent canal flow. For the flow between 2-10 percent, double bifurcators (Fig. Appendixes E-1) are used with secondary splitter to achieve the desired discharge. Relative lower discharges are obstructed through open flumes (OF) and adjustable orifice semi module (AOSM).

3.1.2 Crop Based Irrigation Operation (CBIO) Implementation The concept of crop based irrigation operation (CBIO) is to reduce the amount of groundwater recharge, which will consequently reduce waterlogging as compared to supply based system. The CBIO is modification of supply based system due to increased water allowance in the study area (Pongput 1998). It has been designed to replace the fixed schedule warabandi system, which oversupplies at early and late crop growth stages and under supplies during peak demand. Canal operations under CBIO started in December 2003 but PHLC discharge dropped by almost 50 percent (from 19.83 m3s-1 to 9.92 m3s-1 P

P

P

P

P

P

P

after CBIO implementation, as half the offtakes were alternately closed for one week due to low demand. Presently CBIO has been abounded by the Operation and Regulation Cell of Swat Area Water Board (SAWB) because of the resistance from FOs who wanted water for tobacco and hybrid maize.

43

3.1.3 Institutional Setup The Frontier Irrigation and Drainage Authority (FIDA) is an autonomous organization and established through legislation of NWFP Irrigation and Drainage Authority Act 1997, an innovative act to devolve power in the irrigation and drainage sector. FIDA is responsible for managing the irrigation system from barrages to canal head works only. The Authority has established pilot Swat Canal Area Water Board (SCAWB), Mardan. Farmers’ Organizations (FOs) are established on the distributaries and minors which will take care of the water distribution to the farmers. They maintain the distributaries, minors and watercourses and collect ISF i.e. water charges (Abiana) from the farmers. FIDA is supervised by a Board in which farmers play an important role.

3.2

PROPOSED IRRIGATION MANAGEMENT INFORMATION SYSTEM

The importance of relevant and appropriate information in decision making cannot be overemphasized. Day-to-day management frequently plays an essential role in water conservation. Information is vital since daily decisions regarding irrigation delivery and other aspects affect the well-being of many farmers. In Provincial Irrigation Department (PID) necessary conditions existed in accordance with established rules and bylaws, and there were mechanisms for processing of these data to help managers to identify performance deficiencies. However, the procedures followed were laborious and some time, it was not possible to get the timely feed back of actual performance level to the managers for their judgment and decision. Traditionally, Provincial Irrigation

44

Department (PID) processes data manually, the consequence which was, that relevant information was either not available or it used to be incomplete and many adhoc decisions were made. It was realized that there is a need for improved data collection, recording and transmission procedures, to mitigate the drawbacks of previous data collection by PID.

The success in implementing irrigation management information system (IMIS) is largely attributed to preliminary diagnosis. The first step for the development of irrigation management information system (IMIS) is to establish data collection mechanism, so that FOs President of distributary gets timely feedback on actual performance. The basic data for cropping pattern and intensity was obtained from sampled farmers as explained in detail in Section 3.3.5. A simple worksheet based irrigation management information system (IMIS) has been developed for the purpose of facilitating the operation and monitoring tasks of irrigation systems by allocating irrigation water at various offtakes to meet the irrigation demand of farmers and maintaining equity of water distribution (Fig. 3.2).

45

SCAWB

FOs

Calibration of Head Regulator and Outlers

Topographic Survey and Hydraulic Data of Distributary Structures

Effective Rainfall

Monitoring Waterlevel at Intake and Outlets by Hydraulic Committee

Daily Inflow at Distributary Intake

Simulation of Canal Operation SIC Hydrodynamic Model

Operation of Irrigation Network and Adjustment of Flow

Irrigation Demand at offtake

ETo Referene Evapotranspiration

Meteorological Data

Calibration and Validation of SIC Hydrodynamic Model

Performance Evaluation based on Selected Indicators Cultivation Calender and Cropping Patteren

Monitoring and Control

ISF

Operators

Farmers

Fig. 3.2 Irrigation management information system (IMIS).

46

Culturable Commanded Area

3.2.1 Data Structures The IMIS (Fig. 3.2) is developed in MS Excel on the window 98 environment. The model is an Excel file that is called workbook, which contains many worksheets. The Excel workbook of the IMIS model is for only one distributary. There are ten worksheets; namely;

‰ Title

Name of distributary and basic files information.

‰ SCIA

Seasonal cropping intensity and area under each crop.

‰ CC (S,W)

Annual cultivation calendar including planting and harvest dates, cultivated area based on actual cropping intensity during summer and winter.

‰ Kc

Crop coefficient during different growth periods.

‰ Weighted Kc

Determination of weighted Kc using equation (3.3);

‰ Irrigation Demand

Total 10-days irrigation demand including crop water, leaching requirements and losses.

‰ Supply at Intake

Supply at intake and daily water levels at the distributary intakes converted to discharge using head discharge equations (Table 3.2).

‰ SAQ

Statistical analysis of discharges based on 10-daily period.

‰ Irrigation Supplied

Based on statistical analysis of discharge, irrigation supplied at intake is computed.

‰ PPC

Performance parameters sheet calculate Relative water supply (RWS), Delivery performance ratio (DPR), Reliability (PD) using equations 3.1, 3.4 and 3.5 respectively.

This program is limited to the irrigation management aspects and it covers the major issues of day-to-day management activities and also includes performance oriented operation and monitoring of the infrastructure.

47

3.2.2 Method of Information Generation Typical routine data collection consist of annual cultivation calendar, seasonal cropping pattern and cropping intensity i.e. area under each crop in selected outlet command area through farmers interviews, during the meetings with FOs using structured questioners proforma. The methodology is discussed under section 3.31 and 3.3.5.

Irrigation demand option provides computation of the irrigation demand for 10 days period based on the existing cropping pattern and intensity. The required irrigation demand is communicated to SCAWB by the President of selected distributaries. Accordingly the operators of SCAWB adjust the head regulator of the distributaries. FOs monitors the water levels at the head regulator whereas hydraulic committees of the individual Water Users Associations (WUA) monitor the water levels at outlets. Daily water levels are submitted to the respective FOs Office. The computer operator feed the water levels in IMIS programme that evaluates the performance of selected distributaries as discussed in detail in Chapter V. The evaluated performance was also discussed with officials of SCAWB and President of FOs. They were convinced based on the analysis that farmers are applying approximately twice as much water as needed.

Furthermore, in consultation with Swat canal Area Water Board (SCAWB), Chowki Distributary was selected for detail evaluation using IMIS in association with the Simulation of Irrigation Canal (SIC) hydrodynamics model. SIC was

48

used to evaluate the effectiveness of the physical infrastructures discussed in Section 5.8 and simulated different operational scenarios discussed in Section 5.9 to improve the operation and control the wastage of irrigation water due to enhanced water allowance of the Chowki Distributary .

3.3

DATA COLLECTION METHODOLOGY

3.3.1 Description of Selected Site Six distributaries and minors (Table 3.I) of Maira Branch canal were selected for evaluation the impact of irrigation management transfer turnover (IMT). The farmers’ organizations (FOs) on these distributaries were formed during 2003 that belongs to Swat Canal Area Water Board (SCAWB).

The farm size and land tenure system has a major impact on the agricultural development of the area, because the large farms have a comparatively higher absorptive capacity for development than the small farms. In the study area, 50 percent of the irrigated land is cultivated by the land owners, 30 percent by owner-cum tenants and 20 percent by the tenants. The higher representation of the owners helped in formation of FOs as the land owners took more interest and initiatives to share responsibilities in collective actions. In selected distributaries 70 percent of the farmers have farm size less than 2 ha, 20 percent have farm size ranging from 2-4 ha and only 10 percent have farms of 4 to 10 ha.

49

Table 3.1 Salient features of selected distributaries. RD* (m)

Discharge (m3s-1)

GCA (ha)

CCA (ha)

Number of stakeholders

1

Name of distributary Yaqubi

19020

1.00

1546

1354

1153

2

Gumbad-II

35020

0.85

1373

1150

597

3

Qasim-II

41740

0.67

1013

911

330

4

Toru

43150

0.91

1437

1250

352

5

Chowki

44550

3.10

4580

4305

1485

6

Pirsabak

44550

2.39

3735

3181

1669

No.

P

P

P

P

*RD - Reduced distance i.e. distance from the head or intake of canal. 1RD = 304.9 m (1000 feet)

3.3.2 Calibration of Hydraulic Structures The selected distributaries are equipped with head gate regulators. Crump’s weirs are installed in the head reach of each distributary for monitoring the flows. Benchmarks were established on the head walls of the distributaries, which were used as reference points for measuring water levels to calibrate the Crump’s weirs. Head discharge relations were developed at different flow levels using area velocity method (measuring the cross section area of the canal at selected section and determining the flow velocity through the cross section using current meter).

Daily water levels were measured at selected

distributaries. For all the distributaries the head discharge equations were developed as function of upstream water levels (Hu) to determine the B

discharges as given in Table 3.2.

50

B

Table 3.2 Head discharge relations of selected distributaries. Name of RD* Head (m) and Discharge(m3s-1) No. distributary (m) Relations

Yaqubi

19020

5 6

Gumbad-II Qasim-II Toru Chowki Pirsabak

35020 41740 43150 44550 44550

P

0.84

Q = 3.96*(Hu)1.5

0.98

B

B

P

B

B

2 3 4

P

Q = 5.2*(3.281Hu+0.92)2.07 for Hu>0.19 m B

1

R2

P

P

Q = 3.96*(Hu)1.5 Q = 3.92*(Hu)1.5 Q = 3.96*(Hu)1.5 B

B

P

B

B

P

B

B

P

Q = 3.96*(Hu)

1.5

Q = 6.93*(Hu)

1.5

B

P

P

0.98 P

B

B

0.97 0.99 0.99 P

P

P

P

0.98

*RD - Reduced distance i.e. distance from the head or intake of canal. 1RD = 304.9 m (1000 feet)

3.3.3 Discharge Measurement After calibration of the hydraulic structures and developing of head discharge relations, daily water levels were observed which were converted into discharges for the year 2007 (Figures

3.4 to 3.9). Frequency analyses of

discharge (percent of design discharge) are given in Table 3.3. The data shows that annual closure of all the distributaries was for a period of seventy five days. The period was more than the actual recommended period of one month. The analysis of discharges shows that Gumbad-II Distributary draw more than 110 percent of design discharge for 2 days (one percent of operation time).

51

Table 3.3 Frequency analysis of discharges. Yaqubi

Distributaries Percent of design discharges

Gumbad-II

Qasim-II

Toru

Pirsabak

Chowki

No. of Percent No. of Percent No. of Percent No. of Percent No. of Percent No. of Percent days of time days of time days of time days of time days of time days of time

>110

0

0

2

1

15

5

6

2

5

2

0

0

101-110

8

3

21

8

38

14

37

13

52

19

1

0

91-100

16

6

93

33

60

21

80

29

71

25

11

4

81-90

72

26

36

13

38

14

48

17

84

30

62

22

71-80

109

39

47

17

44

16

28

10

36

13

135

48

61-70

36

13

23

8

23

8

17

6

19

7

30

11

70 mm ⎭

Where : Effective Rainfall (mm.day-1) : Total rainfall over the growing season (mm)

Pe Pt

P

B

P

The CROPWAT (FAO, 1998) programme based on Penman-Monteith equation was used for determination of daily ETo (mm.day-1). Spreadsheet was B

B

P

P

developed for calculation of ETc of crops using Eq. 3.3 for multiple crops on ten B

B

daily bases. The crop coefficient (Kc) values for different crops and growth stages were obtained from Doorenbos and Pruitt (1984), Allen et al. (1998), and On Farm Water Management (OFWM), Irrigation Agronomy Field Manual (1997). ⎧ ∑ K C * A Cropped ⎫ ⎪ ⎪ ETC = ETo * K C = ETo * ⎨ 10 - days ⎬ .......................................................... (3.3) ⎪ ∑ (A Cropped ) ⎪ ⎩ Total ⎭

Where ETc ETo Kc KC

3.4.2

: : : :

Crop Evapotranspiration (mm.day-1) Evapotranspiration of Reference Crop (mm.day-1) Crop Coefficient Weighted Crop Coefficient

Delivery Performance Ratio (DPR)

DPR is defined as the ratio of the actual discharge to the design discharge (Clemmens and Bos 1990, Bos et al. 1994).

60

1 T

DPR =

⎛ Qa ⎞ ⎟⎟ ........................................................................................ (3.4) ⎝ d ⎠

∑ ⎜⎜ Q n

Where, Qa : Actual discharges delivered (m3s-1) Qd : Design discharge (m3s-1) B

B

B

B

Molden et al., (2007) discussed the characteristics of DPR (Eq. 3.4) classifying it as the most important hydraulic and operational performance indicator. It enables the manger to determine the extent to which the water actually delivered against the design discharge. The DPR (Eq. 3.4) allows for instantaneous checking of whether discharges are more or less than the design or target discharges.

The operational objectives of irrigation systems are to provide the equitable distribution of available irrigation supplies to all the stakeholders as efficiently and effectively as possible. The outlets are designed to provide the design discharges based on full supply level (FSL) in the canal. Equitable distribution of irrigation water is controlled by maintaining the canal water surface level for a given discharge and it is achieved by properly operation of water control structures as well as constant monitoring of the water levels at control points located along the length of canal and at tail clusters.

The nominal range of the proportionality is 70 to 110 percent of the design flow. Rotational flows operational strategy is adopted between the distributaries and

61

offtakes (outlets), when incoming flows to the canal system are between 55 to 60 percent of the design flow because at low flows proportionality become more difficult to maintain and misappropriation of irrigation supplies to offtakes (outlets) increases.

Based on preceding discussion on operation philosophy of irrigation system in Pakistan, it is logical to accept the minimum lower DPR of 0.7 and upper limit above 1.3 is considered as poor performance. The assessment criteria adopted in this study is: 0.9 ≤ DPR ≤ 1.1 good performance; 0.9 - 0.7 ≤ DPR ≤ 1.3-1.1 satisfactory performance and 1.3 ≤ DPR ≤ 0.7 poor performance.

3.4.3 Reliability (PD) B

B

Reliability of water distribution indicates the ability of system to deliver the design irrigation supplies in given time span. In context of Pakistan a system that achieves steady state is considered as reliable. Reliability of deliveries are an essential condition for confidence building between AWB and FOs, and indicates the ability of the system to deliver design supplies in a given time span.

It is considered essential for charging irrigation service fee and for

successful move towards technical and institutional measures aiming at better water

management

through

farmers’

maintenance of the irrigation system.

62

participation

in

operation

and

Molden and Gates (1990) defined the reliability (PD) as the degree of temporal B

B

variability in the ratio of amount delivered to the amount required over a region. Reliability of water distribution is calculated as given in Eq. 3.5.

PD =

1 R

∑ CV

T

R

⎛Q Where CVT ⎜⎜ a ⎝ Qd

⎛ Qa ⎜⎜ ⎝ Qd ⎞ ⎟⎟ ⎠

⎞ 1 ⎟⎟ = ⎠ R

∑ CV (DPR ) ……………………………............. (3.5) T

R

is temporal coefficient of variation (ratio of standard

Q deviation to mean) of the ratio ⎛⎜ a Q ⎞⎟ over time period T. The criteria d ⎠ ⎝

suggested by (Molden and Gates,1990) is, if CVT (DPR) ≤ 0.10 reliability of B

B

irrigation supplies is good, whereas 0.10 ≤ CVT (DPR) ≤ 0.20 it is satisfactory and B

B

CVT (DPR) ≥ 0.20, it is poor. B

3.5

B

MODEL SELECTION

Rapid developments have been made in application of computer models in recent years. These tools are extensively used in irrigation and drainage engineering. In these fields commercial softwares are now available for a number of different aspects including planning, design, management and operation of irrigation systems as already discussed in detail in Chapter II. Potentially hydraulic simulation models are employed in the field of irrigation engineering, mainly at the conveyance and distribution levels of irrigation networks to test the effectiveness and efficiency of different operational procedures. The Simulation of Irrigation Canal (SIC) developed by CEMAGREF (1995) has been particularly dedicated to irrigation canals. It is equally useful to engineers

63

and canal managers. It has been already used in many different countries: France, Sri Lanka, Pakistan, Burkina Faso, Mexico, Jordan, and Senegal. In Pakistan SIC has been used in by International Water Management Institute (IWMI) Lahore, Water and Power Development Authority (WAPDA), Center of Excellence in Water resources Engineering (CEWRE), Lahore and Operation and Regulation Cell (Swat Canal Area Water Board) NWFP, Mardan. SIC is a simulation tool, once it has been properly calibrated to a physical condition of the canal, the software can be used to simulate the behaviour under various operational scenarios and impact of legal and ill legal interventions on water distribution. This model has good library of hydraulic structures and global performance indicators under unsteady flow conditions. This application for hydraulic modeling is indispensable, since testing canal control algorithms on real systems in practice is extremely difficult if not possible. Testing the algorithms using hydraulic modeling is essential before implementing any model on real systems. The SIC hydraulic model combines efficient numerical algorithms and up-to-date user friendly interfaces. Developed in close collaboration with the engineers and managers partners of the SIC User's Club, it fulfills most of the user's needs, as far as irrigation canals are concerned. Based on the above attributes, SIC model was selected in the present study. Some more description of the SIC model is given in Chapter-IV.

3.5.1 Model Input Data Application of model requires site specific field data collection to define and calibrate the model. Study oriented data is needed to be collected to interpret

64

and evaluate particular scenarios. The description of the model data input used for Chowki Distributary is described below: ‰ Topographic and geometric data ‰ Hydraulic data The input data is requirement for the study and unsteady states are the same.

3.5.2 Topographic and Geometric Data Topographic survey of the Chowki Distributary was conducted during the closure period of 2006-07. All data is given in Appendix Tables C-1 to CIII. The following data was collected: ‰ longitudinal profile survey of the Chowki Distributary and its Minors. ‰ bed and bank elevation, bed width of the canal measured approximately at every 100 m. ‰ cross section of the distributary and minor at regular intervals of 50 m. ‰ exact location of head regulator, offtakes (outlets), dimension and crest levels of all offtakes (outlets).

3.5.3 Hydraulic Data Hydraulic survey was conducted because the flows diverted to the offtakes are simulated through these information. These data include following measured and computed hydraulic parameters. ‰ roughness coefficient for the different reaches of the distributary and minors. ‰ head discharge relation and discharge coefficient for the offtakes (outlets). ‰ downstream boundary condition. There are 27 inline cross structures exist to control the discharge, were monitored (width and crest elevation) and inserted as singular section in the model. Throat width, sill elevation of twenty eight offtakes (Tables 3.6 and 3.7) were physically

65

measured and inserted as node in SIC model. Downstream boundary condition for Chowki Distributary and its two minors were based on actual water levels and discharge was feed as rating curve in the model. The inflow to the network is considered as initial value and taken positive, whereas outflow on offtakes nodal points is taken negative. Table 3.6 Data of the Chowki Distributary. qd

Offtake Structure

CCA (ha)

(m3s-1)

Bt (mm)

Bed Level (m)

CL (m)

L

OF

51

0.04

110

354.77

355.04

309

R

OF

132

0.09

76

354.77

354.86

3

819

L

D

BIF

169

0.12

200

352.23

352.33

4

987

L

D

BIF

259

0.18

315

349.73

349.83

5

1867

L

OF

77

0.05

60

335.01

335.08

6

1877

R

OF

135

0.09

94

335.00

335.08

7

2063

R

OF

55

0.04

60

332.64

332.72

8

2795

L

D

BIF

130

0.09

197

325.52

325.62

9

2795

R

S

Chowki I

1121

0.78

650

325.52

325.62

10

2970

R

OF

115

0.08

87

323.73

323.80

11

4289

L

S

TRI

166

0.12

206

323.22

323.37

12

4289

R

S

TRI

149

0.10

174

323.22

323.37

13

5510

R

OF

73

0.05

62

322.62

322.69

14

5930

L

S

TRI

195

0.14

196

322.47

322.65

15

6185

L

S

16

6185

R

S

17

6890

L

18

7622

L

RD (m)

Side

1

260

2

No

Type

B

P

P

B

P

P

Chowki-II (TRIF) BIF

677

0.47

784

321.27

321.54

199

0.14

230

321.27

321.54

OF

15

0.01

70

316.71

316.76

BIF

150

0.10

529

310.68

310.95

19 7622 R S BIF 104 0.07 383 310.68 RD - Reduced distance i.e. distance from the head or intake of canal. 1RD = 304.9 m (1000 feet) Bt: Throat Width; CL: Crest Level; qd : Design Discharge; L : Left ; R : Right; C: Center; S : Single ; D : Double; BIF: Bifurcator; TRI: Trifurcator ; OF : Open Flume; FSL: Full Supply Level.

310.95

S

66

Table 3.7 Data of the Chowki Minors. No

RD (m)

Side

Type

Offtake Structure

CCA (ha)

qd B

B

3 -1

(m s ) P

P

P

P

Bt (mm)

Bed Level (m)

CL (m)

Chowki Minor -I 1

1060

L

TRI

290

0.20

520

314.89

315.31

2

1060

R

TRI

138

0.10

250

314.89

315.31

3

1060

L

TRI

92

0.06

160

314.89

315.31

4

2430

L

S

BIF

337

0.24

570

306.09

306.37

5

2430

C

S

BIF

265

0.19

450

306.09

306.37

Chowki Minor -II 1

919

L

S

TRI

168

0.12

300

318.09

318.26

2

945

L

S

TRI

185

0.13

330

318.09

318.26

3

1825

BF

S

BIF

282

0.20

1306

311.02

311.35

4

1829

BF

S

BIF

42

0.03

194

311.02

311.35

RD - Reduced distance i.e. distance from the head or intake of canal. 1RD = 304.9 m (1000 feet) Bt: Throat Width; CL: Crest Level; qd: Design Discharge; L : Left ; R : Right; C: Center; S : Single ; D : Double; BIF: Bifurcator; TRI: Trifurcator ; OF : Open Flume; FSL: Full Supply Level.

67

CHAPTER IV SIMULATION OF IRRIGATION CANALS (SIC) MODEL The SIC (Simulation of Irrigation Canals) software is a mathematical model which can simulate the hydraulic behaviour of the irrigation canals, under steady and unsteady flow conditions. The SIC model is an efficient tool allowing canal managers, engineers and researchers to quickly simulate a large number of hydraulic conditions at the design or management level. The model is based on one-dimensional hydraulic analyses for transitional and steady state flows. It is divided into a topographical unit and two separate computational units for steady and unsteady flows respectively. Computational accuracy of the SIC model is better than the other similar software (Contractor et al. 1993). The detailed discussion regarding the mathematical formulation and operation procedures are well documented by Baume et al. (2003).

4.1

TOPOGRAPHIC MODULE

Unit I is used to create the topography and geometry files to be further used by the computational programs of Unit II and III. Unit I allow to input and verify data obtained from a topographical survey of the canal or from design documents. Unit I consists of three programs: EDITAL, TALWEG and RESTAL.

A main canal network is a water distribution system, which conveys water from a source (reservoir or river diversion) to various offtakes that deliver water to user groups via secondary and tertiary canals. The hydraulic modeling of such a network needs to take into consideration the real canal topography in addition

68

to its geometric description. All the topographic components used by the model are managed in Unit 1. For one-dimensional hydraulic modeling, each reach is described by n cross-sections perpendicular to the main flow direction (Fig. 4.1). Cross-sections are chosen to represent as closely as possible the shape and the slope of the reach.

Fig. 4.1 Cross sections in a reach (Baume et al. 2003). If the distance between two data cross-sections is too great, intermediate cross-sections are computed by numerical interpolation in order to improve the accuracy of the computed backwater curve.

4.1.1 Description of the Hydraulic Network The hydraulic network is divided into homogeneous sections, the reaches being located between an upstream node and a downstream node. Relations between reaches occur only at the nodes. One can create a different reach for a lined canal zone (low roughness), and an unlined canal zone (high roughness). The division into reaches does not influence the results of the hydraulic calculation. If different regulating or control devices exist across the

69

canal, they can be integrated within a reach and do not need any special division. This approach facilitates the modeling of the hydraulic transition from free flow conditions to submerged conditions at such devices. A branch is a group of reaches serially linked to one another. The division into reaches and branches is shown in Figure 4.2.

Fig. 4.2 Canal network subdivided into reaches and branches.

4.1.2 Classification of Reaches Reaches are identified by their nodes. The position of a reach in the network is entirely defined by the names of its upstream and downstream nodes. The direction of flow is defined at the same time. The reaches constitute the arcs of that graph, delineated by the nodes, upstream and downstream. They are automatically numbered by the program according to the order in which they are input in the data file. The calculation of a water surface profile proceeds upwards, commencing at the downstream end. Therefore, a relationship between water surface elevation and discharge is needed as a downstream boundary condition to start the calculation.

70

4.1.3 Modification in Topographic Data File The first option starts the EDITAL program. This program allows the user to creates, modify or complete a topographic data file (.TAL). This file contains the characteristics of the system (topology, geometry and branches). The (.TAL) files are used by the other programs of unit I. Once in the data editor, the topology is described the nodes are created by selecting in the Tools menu the Node option and by clicking with mouse on the desired site. When nodes are created, one must select the Reach option located on the same menu, then click on the upstream node of the reach, and finally move the mouse and unclick on the downstream node of the reach. The reach is then created and oriented. ‰ The inverse reach option permits to reverse the direction of the flow in

the reach. ‰ The split reach option permits to divide one reach into two reaches with

a new intermediate node. ‰ The merge reaches option permits to join two adjoining reaches and to

erase the intermediate node. ‰ To erase a node or a reach, select in the Tools menu the option Erase

and click on the object to erase. When reaches are described, they are displayed in blue if the coherence test is true and they must be classified into linear branches.

4.1.4 Geometry Computation TALWEG program checks the topographic data file (.TAL) and interpolates cross calculation sections that are necessary for Units II and III files (.MIN),

71

(.GEO), (.TIT) and (.DIS). It is possible to start the program by selecting the Geometry Computation option in the unit I. A window will then permit to the user to select the topographic data file (.TAL) to be treated. The same (.TAL) file name, with the (.MIN) extension, will automatically create the topographic results file, with (.GEO) extension, to create the topographic result file necessary for unit III of the unsteady flow, with (.LST) extension, create the printout file containing information on the program's progress and possible warning or error messages. The (.LST) file permits to visualize possible mistakes. At the end of this stage, the topographic files used by Units II and III are created.

4.1.5 Numerical Results RESTAL program generates a (.LST) file that contains a table giving the description of the calculation sections. The program is started by selecting the Numerical Results option in the main menu of Unit I. The printout files (.LST) and (.MIN) contains all calculation cross sections in width-elevation format, by default.

4.2

STEADY FLOW COMPUTATIONS

Steady flow computations are carried out under Unit II. It allows analyzing the water surface profile for any combination of discharges or settings at offtakes and cross structures. The required setting at offtake is required to satisfy a

72

given distribution plan and maintaining full supply depth targets upstream of cross structures.

4.2.1 Management and Design Mode The option Management Mode allows to modifying main operational parameters. It is useful to test the effect of operations at cross structures or offtakes on the water surface. For cross structures, modify only gate openings and targeted upstream water levels at gates and for offtakes, one can modify only targeted discharges.

This option Design Mode allows to modifying all the hydraulic parameters concerning the canal. It allows testing of the effect of Manning roughness coefficient, seepage or lateral inflow of a new designed canal on the water surface profile. This EDIFLU File menu presents several options: ‰ The first option New permits to create a hydraulic data file (.FLU). ‰ The second option Open permits to modify a hydraulic data file (.FLU). ‰ The third option Verification permits to verify a hydraulic data file (.FLU) and create the corresponding (.DON) file. ‰ The fourth option ESC key permits to exit EDIFLU and return to the SIC main menu.

4.2.2 Calibration Mode The calibration mode is be used to update roughness coefficients (Manning Strickler coefficients) and discharge coefficients of cross structures. The calibration depends on the water levels measured along the canal and

73

discharges of the offtake. These calibration water levels are entered in the same way as the reference levels. The calibration results are written in the (.LST) file. The calibration option must be used, when offtakes switched to the imposed discharge computation mode, since the discharges must have been measured on the real system for the calibration of the model.

4.2.3 Calculation of the Parameters This option permits to modify parameters influencing the calculation algorithm in steady flow, when offtakes are in discharge computation mode or in calibration mode. Default parameters calculate a solution with excellent precision. In certain cases, one can facilitate or accelerate the algorithm convergence using the tuning parameters. The relaxation coefficient accelerate or to slow down the correction of the discharge distribution at the offtakes, during the iterations.

4.3

UNSTEADY FLOW COMPUTATIONS

Unsteady flow computations are carried out under Unit III. It allows testing various distributions plans at offtakes, and operations of main sluices and cross structures (manual or automatic). Starting from an initial steady flow regime, it is be possible to select the best way to achieve a new distribution plan among several options. The efficiency of the operations can be assessed through several indicators computed at offtakes. The program is started by selecting the option Data Editor in the main menu of unit III Unsteady Flow. This program

74

permits to edit (.SIR) files used for unsteady flow calculations (Unit III). Following five options are available and can be used in any order: ‰ Operations at nodes or offtakes (in terms of discharge, opening, weir width, etc., as a function of the time), ‰ Operations at cross structures (in terms of gates opening or weir elevations as a function of time). ‰ Targeted discharges, discharge as functions of the time, for each offtake. These discharges will only be used to calculate the performance indicators at offtakes. ‰ Ponds at nodes, containing the height-surface description of ponds in which some storage will occur in unsteady flow, ‰ Computation parameters, containing the start simulation time, the end simulation time, the time step calculation, and various others parameters used for the calculation in unsteady flow.

4.4

MODELING CAPABILITIES

The SIC model does not handle advance on a dry bed, neither channel dewatering nor hydraulic jumps. When an error is detected during the computation either in steady or unsteady flow a message is displayed in a window, indicating the type of error and the location where illicit flow conditions are detected (e.g. dry bed) and the program stops. Supercritical flow is ignored in steady flow computations, by taking the critical depth at the corresponding locations. Rating curves necessary to be defined as the downstream boundary conditions and at the offtakes. Discharge hydrographs can be defined at nodes.

75

4.4.1 Computational Process The SIC hydraulic model solves the complete Saint Venant equations. It uses the classical implicit Preissmann scheme. The implicit coefficient of θ is set to 0.6. The time step can be selected from 0.01 to 999.99 minutes (default value is 10 minutes). The distance step can be chosen by the user (default value is 200 meters). The gate opening operations can be described at each cross structure and turnout. This can be done through the user-friendly interface or through a regulation module.

4.5

STEADY STATE FLOW CALCULATIONS

Steady flow computations allow analyzing the water profile for any combination of discharges or settings of the offtakes and cross structures. It allows also computing the required settings of the offtakes and adjustable cross structures in order to satisfy a given distribution plan and maintaining full supply depth targets upstream of cross structures. The differential equation of water surface profile in a reach can be written as: dH dx

= −Sf +

⎛ n 2Q 2 and S f = ⎜ 2 4 / 3 ⎜A R ⎝ Where g n R A H q Sf Q B

B

: : : : : : : :

⎛ qQ ⎞ ⎟ ........................................................................(4.1) 2 ⎟ ⎝ gA ⎠

(k − 1)* ⎜⎜

⎞ ⎟ ........................................................................................(4.2) ⎟ ⎠

Gravitational constant = 9.81 m.s-2 Manning coefficient Hydraulic radius (m) Cross section area (m2) Total head (m) Lateral inflow (q>0, k=0) or outflow (q 0 2 Z ci is the critical elevation defined at (i) by ⎛⎜ Qi Bi ⎜ gA 3 i ⎝

⎞ ⎟⎟ = 1 , ⎠

and δ > 0 , subcritical solution, and δ < 0 supercritical solution, and water surface profile is over estimated. This is satisfactory approach to design bank elevation, and offtake are not usually located at supper critical locations and therefore the calculation at these offtake is correct. If a solution does exist, one has to numerically solve an equation of the form f ( Z i ) = 0 . Different approaches are adopted in SIC to solve the equations, with the aim of reducing the size of the matrix used.

77

4.5.1 Loop Computation The aim of the loop computation method is to use a two step approach, where first upstream discharges for each reach are computed and then a standard method is used to compute water profiles inside reaches. As in the case of the Newton-Raphson method, the non-linear system is expanded into Taylor series and only the first order terms are kept. Once an initial state is known it is then possible to compute variations of water elevations and discharges in the entire network.

4.6

UNSTEADY FLOW CALCULATIONS

Unsteady flow computations allow testing various distribution plans at offtakes, and operations of main sluices and cross structures (manual or automatic). Starting from an initial steady flow regime, it will be possible to select the best way to achieve a new distribution plan among several options. The efficiency of the operations can be assessed through several indicators computed at offtakes. SIC package is based on one-dimensional Saint Venant’s partial differential equations that describe flow in open channels. Two equations are needed to describe unsteady flow in open channels, which are the mathematical translation of law of conservation of mass (continuity equation) and momentum. ∂A ∂t

+

∂Q ∂x

= q ................................................................................................(4.5)

The momentum equation or dynamic equation is expressed as:

78

∂ ⎛ Q2 + ⎜ ∂t ∂x ⎜⎝ A

∂Q

⎞ ⎛ ∂z ⎞ ⎟ + g .A⎜ ⎟ = −(gA) ∗ S + K ∗ (qV ) .............................................(4.6) f ⎜ ∂x ⎟ ⎟ ⎝ ⎠ ⎠

The partial differential equations must be completed by the initial and boundary conditions in order to be solved. The boundary conditions are the hydrographs at the upstream nodes of the reaches and the rating curve at the downstream node of the model. The initial condition is the water surface profile resulting from the steady flow computation.

Fig. 4.3 Preissmann four point grid. Saint Venant’s equation has no known analytical solution in real geometry. They are solved numerically by discretizing: the partial derivatives are replaced by finite differences. The discretizing used in the SIC model is four point implicit schemes known as Preissmann’s scheme (Fig. 4.3). This scheme is implicit because the values of the variables at the unknown time step also appear (with those of the known time step) in the expression containing spatial partial derivatives.

79

The derivative ⎛⎜ ∂f ⎞⎟ and ⎛⎜ ∂f ⎞⎟ at point M is written as follows and are used to ⎝ ∂t ⎠ ⎝ ∂x ⎠ discretized Saint Venant’s equations.

f ′− f ⎞ ⎛ f ′− f ⎛ ∂f ⎞ ⎜ ⎟ = 1 2 ⎜ A A + B B ⎟ ......................................................................(4.7) ∆t ⎠ ⎝ ∂t ⎠ M ⎝ ∆t ⎛ f i− f j ⎛ ∂f ⎞ ⎜ ⎟ = 1 2 ⎜⎜ ⎝ ∂t ⎠ M ⎝ ∆t

⎞ ⎟⎟ ......................................................................................(4.8) ⎠

⎛ fi − f j ⎞ ⎛ ∆f − ∆f i ⎞ ⎛ ∂f ⎞ ⎟⎟ + θ * ⎜⎜ j ⎟⎟ ........................................................(4.9) ⎜ ⎟ M = ⎜⎜ ∆ ∆ x x ⎝ ∂x ⎠ ⎝ ⎠ ⎝ ⎠ Discretization of Equation 4.10 yield Equation 4.10(a)

⎫ ⎛ ∆x ⎞ ⎛ ∆x ⎞ ∆Qi − ⎜ ⎟Bj .∆Z j ⎪ ⎟Bi .∆Zi = ∆Qj + ⎜ ⎝ 2θ.∆t ⎠ ⎝ 2θ.∆t ⎠ ⎪ ...........................................(4.10) ⎬ ⎛ Qj − Qi ⎞ ⎛ ∆x ⎞ ⎪ ⎟⎟ − ⎜ ⎟(qi − q j ) + ⎜⎜ ⎪⎭ ⎝ θ ⎠ ⎝ 2θ ⎠

4.7

CROSS STRUCTURES

When cross structures exist on the canal (singular section) the water surface profile equation cannot be used locally to calculate the water surface elevation upstream of the structure. A cross structure can be composed of several devices in parallel, such as gates, weirs, etc. The hydraulic laws of the different devices present in the section must be applied. The modeling of these devices is a delicate problem to solve when developing open channel mathematical models. A distinction has been made between devices with a high sill elevation

80

are called Weir /Orifice and devices with a low sill elevation called Weir / Undershot gates (Fig. 4.4).

Fig. 4.4 Weir – orifice cross device.

Weir – Free flow

Q = µ F ∗ L ∗ 2 g (h1 ) .......................................(4.11)

Weir-Submerged flow

Q = (K F × µ F ) ∗ L ∗ 2 g (h1 )

1.5

1.5

............................(4.12)

Where KF is coefficient of reduction for submerged flow condition. The flow B

B

reduction coefficient is a function of

⎛ h2 ⎞ ⎜⎜ ⎟⎟ ⎝ h1 ⎠

and the value of this ratio

α

at the

instant of the free flow to submerged flow transition are obtained when

⎛ h2 ⎞ ⎜⎜ ⎟⎟ > α = 0.75 ⎝ h1 ⎠

4.7.1 Equation at Singular Section The water surface elevation at a singular section is computed using the equations. The flow at the section is equal to the sum of the discharges through each device (e.g., gate, weir).

81

∑ f (Z n

k =1

k

i

− Z j ) = Q .........................................................................................(4.13)

Where n is the number of devices in the section and Q the flow at the section. f k (Z i − Z j ) = Q is the discharge law of the device number k, for instance for a

submerged weir:

(

)

fk (Zi , Zj ) = µ ∗L ∗ 2g ∗ (Zi − Zj ) ∗ (Zj − Zd ) ............................................(4.14) If the discharge and the downstream elevation Zj are known, the water surface B

B

elevation Zi upstream of the device can then be calculated. B

B

4.7.2 Regulator At each singular section, in steady flow calculation, one particular gate can be chosen to play the role of a regulator. Instead, the model will compute the opening required to maintain a target water level immediately upstream. If the gate opening is unknown and maximum possible opening and the target water elevation (e.g. Full Supply Depth) upstream of the gate is known. This results in an equation at the singular section and ends up with an equation of the following type: Q = ∑ f k (Z i , Z j ) = f r (Z i , Z j , W ) ..................................................................(4.15) n

k =1

Where k = 1 to n: for gates with fixed openings. W : the regulator opening to be calculated. Zi : known value (target upstream water elevation).

82

f k (Z i , Z j ) : The discharge going through the fixed gate number k for the target

upstream water elevation Zi and the downstream water elevation Zj. The B

B

equations considered are those described for the weirs and the gates.

f r (Z i , Z j , W ) : The discharge going through the regulator type gate for an

opening W and the target upstream water elevation Zi. The f k (Z i , Z j ) are B

known values. Then equation (14) is reduced to f r (Z i , Z j , W ) = constant. One then has to look for the zero of a function, but this time, the unknown is W.

4.7.3 Offtakes Equations The lateral offtakes corresponds to points of outflows or inflow. Therefore, they are obligatorily located at nodes (Fig. 4.5). Under steady flow conditions, SIC can compute the real offtake discharge corresponding to a given offtakes gate opening corresponding offtakes gate opening.

Fig. 4.5 Lateral offtake.

83

The offtakes are modeled according to the same hydraulic laws as for cross structures. The originality of the approach stands on the consideration of a possible influence of the offtake downstream condition with out modeling completely downstream lateral canal.

In order to include the possibility of

submerged flow conditions at the offtakes, three types of offtake downstream conditions (i.e., at the head of the secondary canal) can be modeled: ‰ a constant downstream water surface elevation. ‰ a downstream water surface elevation Z2 that varies with the water B

B

surface elevation upstream of a free-flow weir:

Q( Z 2 ) = µ * L * 2 g * (Z 2 − Z D )

1.5

.......................................................(4.16)

‰ a downstream water surface elevation that follows a rating curve of

the type: ⎛ (Z − Z D ) ⎞ ⎟⎟ ..................................................................(4.17) Q ( Z 2 ) = Qo * ⎜⎜ 2 ⎝ (Z o − Z D ) ⎠ n

4.8

PERFORMANCE INDICATORS

Some performance indicators have been incorporated for the evaluation of the water delivery efficiency at the offtakes. They allow integrating the information on water delivery, either at a single offtake or at all the offtakes. There are two kinds of indicators: volume indicators and time indicators.

4.8.1 Volume Indicators The volume indicators refer to three kinds of volumes: ‰ The demand volume(VD) which is the target volume at the off-takes, ‰ The supply volume (VS) which is the volume supplied at the offtakes, ‰ The effective volume (VEF), which is really the usable part of the supply volume. B

B

B

B

B

B

84

The definition of the effective volume depends on two coefficients: W and X (in percent).Only the supply discharge close to the water demand is thus taken into account (Fig. 4.6).

w ⎞ x ⎞ ⎫ ⎛ ⎛ If ⎜1 − ⎟.QD ≤ QS ≤ ⎜1 + ⎟.QD ⇒ QEF = QS ⎪ ⎝ 100 ⎠ ⎝ 100 ⎠ ⎪ w ⎞ ⎪ ....................................(4.18) ⎛ If QS < ⎜1 − ⎟.QD ⇒ QEF = 0 ⎬ ⎝ 100 ⎠ ⎪ ⎪ x ⎞ x ⎞ ⎛ ⎛ If QS > ⎜1 + ⎟.QD ⇒ QEF = ⎜1 + ⎟.QD ⎪ ⎝ 100 ⎠ ⎝ 100 ⎠ ⎭ The total effective volume (VEF) over a period of time T is given by following B

B

Equation (4.20):

T

V EF = ∫ Q EF dt ..........................................................................................(4.19) 0

Fig. 4.6 Definition of effective volume.

85

Adequacy: indicator measures the performance of the scheme in terms of adequacy for offtakes between the head inlet and the target delivery point. Adequacy for an offtake is expressed as the ratio of effective volume (VEF) to B

B

targeted volume (VD). B

⎛V = ⎜⎜ EF ⎝ VD

Adequacy

B

⎞ ⎧ 1 T ⎫ ⎟⎟ = ⎨ ∫ Q EF dt ⎬ .................................................................... (4.20) ⎠ ⎩VD 0 ⎭

Operational Efficiency: indicator is the ratio of effective volume at the delivery point within the targeted period of time, to the volume issued from the main supply (Vs). The effective volume (VEF) is computed with restriction to the B

B

expected period of delivery as follows: T2

VEF = ∫ QEF dt ..................................................................................................... (4.21) T1

⎛V E op = ⎜⎜ EF ⎝ VS

⎫ ⎞ ⎧ 1 T2 ⎟⎟ = ⎨ ∫ Q EF dt ⎬ .................................................................................. (4.22) ⎭ ⎠ ⎩ V S T1

Where T1 is expected arrival of wave and T2 is expected finish of the wave. B

B

B

B

From the above definitions, DPR can obtain as follows:

⎛V DPR = ⎜⎜ S ⎝ VD

⎞ ⎛V Vs ⎟⎟ = ⎜⎜ EF × V EF ⎠ ⎝ VD

⎞ ⎟⎟ ................................................................... (4.23) ⎠

4.8.2 Time Indicators The time indicator is define TD as the total period of time during which the B

B

demand discharge is non-zero and TEF as the total period of time during which the effective discharge is non-zero. Time indicator compares the duration of

86

delivery of the effective volume with that of the demand volume. This indicator is dimensionless and can only be calculated for individual offtakes, it doesn't have any significance for all the offtakes taken together. Baume et al. (2005) define two time lags i.e. ∆T1 ,

∆T2 . ∆T1

is the time separating the start of the

water demand and the start of the effective discharge. This time is positive if the effective discharge arrives after the demand discharge (Figure 4.7).

Fig. 4.7 Definition of time indicator. Where ∆T2 , is the time lag between the centers of gravity of the demand and the effective delivery hydrograph. All these indicators are defined for each offtake. They can be calculated for any particular period of the simulation that the user wants to focus on. The effective duration of the delivery at tail (TEF) is B

B

the total duration for which discharge is above the minimum limit. The indicator of effective duration at tail is the ratio of effective duration (TEF) to targeted B

duration (TD). B

B

87

B

Chapter V RESULTS AND DISCUSSION

5.1

IRRIGATION MANAGEMENT INFORMATION SYSTEM

Irrigation management information system (IMIS) is prerequisite for irrigation management turnover to response to the needs of end users. Performance and operational efficiency can be enhanced if good communication system exists to provide necessary feedback on the status of the system. The irrigation management information system envisaged in this study has been explained in Chapter III in schestimatic way of gathering, organizing, storing and making available information’s regarding cropping calendar, cropping pattern, intensity, actual irrigation water supplied and demand to farmer organizations and operators of the irrigation system. The IMIS is helpful tool for monitoring the irrigation systems and to evaluate their performance based on selected performance indicators.

5.1.1 Cropping Pattern and Cropping Intensities Land, water and climate play an important role in selection of crops. Agroclimatic conditions of the study area are suitable for year round cultivation. Cropping intensities is an index reflecting farm activities and it increases significantly with assured and adequate irrigation water supplies. The irrigation supplies not only influence the cropping pattern but use of inputs is directly related to water availability. Irrigation intensities were determined by

88

interviewing the farmers and it was confirmed by walking along the watercourses. The cropping intensity was found to be 80 percent and 90 percent respectively in summer and winter seasons. Thus making annual cropping intensity of 170 percent (Table 5.1). Pre IMT data show 145 percent annual cropping intensity thus indicating an increase of 25 percent in the intensity. Whereas projected intensity was 190 percent.

Table 5.1 Pre and post IMT annual cropping intensities in the study area. Summer Season

Winter Season Intensity (%)

Planting Date

Days

Pre IMT

Post IMT

21-Jun

110

25

20

11-Jul

120

20

15

15-Feb

120

5

7

1-Mar

120

5

6

Sugarcane

1-Oct

360

9

Orchard

1-Oct

360

5

Vegetables

1-Nov

Crop

Maize Tobacco

Fodder Other

Crop

Planting Date

Intensity (%) Days

Pre IMT

Post IMT

15-Oct

120

25

30

11-Nov

120

20

20

Sugar beet

1-Oct

210

2

7

15

Sugarcane

1-Oct

360

9

15

5

Orchard

1-Oct

360

5

5

2

5

Vegetables

31-Oct

3

5

Wheat

1-Apr

120

1

2

Oil Seed

1-Oct

210

1

1

1-Jun

120

1

2

Fodder

1-Sep

195

1

4

1-Apr

185

2

3

Other

1-Sep

120

4

3

75

80

70

90

Total

Total

The principal crops grown in the study areas are wheat and sugarcane. Wheat is the main cereal crop that is sown from the 2nd week of October to last week of December mostly in traditional manner of broadcasting. Sugarcane has two planting seasons: winter (October) and summer (February). It is the main cash crop. October planting is for safeguarding the buds of the seedling cane from

89

frost and extends the growing period to achieve higher production. According to farmers, the sugarcane planted in the area is intercropped with wheat and sugar beets in winter and with tobacco in the summer. The normal growing period of sugarcane is 10 to 12 months. The ratoon crop is used for two to three cropping seasons after which it become uneconomical due to reduction in yield. Sixteen to twenty irrigations are recommended depending on the variety grown, soil and weather conditions. Farmers applied light and frequent irrigation during germination and seedling stage of cane.

Tobacco is another important cash crop and it is planted from 15th November to P

P

15th December on nursery beds. The seedlings are then manually transplanted P

P

in the fields from 15th February to 15th March and harvested during June. The P

P

P

P

Tobacco is mainly virginia varieties (Spade and Kokar) supplied by the tobacco companies. Farmers usually apply six to seven irrigations depending on weather condition. The first irrigation is applied immediately after transplanting and second after one week to ten days interval. Maize is the main summer cereal crop and its present cropping intensity is 35 percent. The maize crop is mostly sown by traditional method of broadcasting from 15th July to 15th August. P

P

P

P

This results in a thick population which is then thinned. The plants removed are used for fodder and remaining plants are allowed to mature for grain. Cultivation of maize as a grain-cum-fodder crop is one of the reason for low grain yield.

90

5.2

RELATIVE WATER SUPPLY

The primary objectives before irrigation management turn over were equity of water distribution and reliability of irrigation deliveries. Whereas, adequacy was not significant objective as system was operated under supply based. After IMT and modernization of Maira Branch of Upper Swat Canal, the irrigation system is operated more in demand responsive mode and irrigation supplies better match the crop water demand. Therefore, adequacy of irrigation supply becomes important criterion from farmers perceptive.

The knowledge of

evapotranspiration and irrigation intensities is important to determine the potential demand. This enables the system manger to adjust the gate and deliver water more or less in broad pattern of demand.

The adequacy is assessed by relative water supply (RWS) by converting the actual discharges into equivalent depth of water. RWS gives better understanding of how farmers behave. The RWS of 2.0 means that twice as much water is available than required, then the farmers are naturally relaxed in managing water distribution. As RWS reached to 1.0, there need for more management and as it approaches to 1.2, high degree of organization is required to let every farmers have their faire share. The relative water supply (RWS) index was determined for the ease of analysis on 10-daily bases i.e. looking average condition of 10-days period throughout the year (Fig. 5.1 to 5.6). This approach smoothes out the curve and ignores the small fluctuations in discharges. RWS on monthly basis is also shown in (Table 5.2) for overview. The RWS is based on actual area cultivated in a particular season. This

91

procedure is adopted to measure the adequacy of irrigation supplies and to know how farmers are actually irrigating their land. It is evident from Table 5.2 that the RWS values was very high during the months of November and December indicating over irrigation and flexibility in farm irrigation operation. The situation was confirmed by interviews and discussions with the farmers. It was further revealed that rotational water distribution (warabandi) schedules at tertiary level are not practiced strictly and mostly farmers do not irrigate at night time.

6.0

Relative Water Supply

5.0 4.0 3.0 2.0 1.0

Fig. 5.1 Relative water supply of Yaqubi Distributary.

92

Sept II

Aug III

Aug I

July II

June III

June I

May II

April III

April I

March II

Feb III

Feb I

Jan II

Dec III

Dec I

Nov II

Oct III

Oct I

0.0

93

Fig. 5.3 Relative water supply of Qasim-II Distributary. 2.0

1.0

0.0 July II

June III

June I

May II

April III

April I

March II

Feb III

Feb I

Jan II

Dec III

Dec I

Sept II

3.0

Sept II

4.0 Aug III

5.0

Aug III

6.0 Aug I

Fig. 5.2 Relative water supply of Gumbad-II Distributary.

Aug I

July II

June III

June I

May II

April III

April I

March II

Feb III

Feb I

Jan II

Dec III

Dec I

Nov II

Oct III

Oct I

0.0

Nov II

Oct III

Oct I

Relative Water Supply

Relative Water Supply 7.0

6.0

5.0

4.0

3.0

2.0

1.0

94

June I

May II

April III

April I

March II

Feb III

Feb I

Jan II

Dec III

Dec I

Nov II

Oct III

Oct I

Sept II

0.0 Sept II

1.0 Aug III

2.0

Aug III

3.0 Aug I

4.0

Aug I

5.0 July II

6.0

July II

7.0 June III

Fig. 5.4 Relative water supply of Toru Distributary.

June III

June I

May II

April III

April I

March II

Feb III

Feb I

Jan II

Dec III

Dec I

Nov II

Oct III

Oct I

Relative Water Supply Relative Water Supply

7.0

6.0

5.0

4.0

3.0

2.0

1.0

0.0

Fig.5.5 Relative water supply of Pirsabak Distributary.

6.0

Relative Water Supply

5.0 4.0 3.0 2.0

Sept II

Aug III

Aug I

July II

June III

June I

May II

April III

April I

March II

Feb III

Feb I

Jan II

Dec III

Dec I

Oct III

Oct I

0.0

Nov II

1.0

Fig. 5.6 Relative water supply of Chowki Distributary. Water delivery pattern is not related to ETo (Appendix Fig. B-3 and B-4). In the early part of the year during the months of Jan to March-II because the irrigation system was closed for annual repair and farmers rely only on rainfall. Whereas, From March II to June III, irrigation deliveries exceed the ETo, this meant that there is excess water in the system. Irrigation deliveries only match the ETo during July to September.

The RWS values for the months of March to October were between 2.00 to 2.70, and during November and December, the values increased further (3.80 to 5.69) suggesting abundant water supply, that cause excess reduction in yield. The RWS graphs for the selected distributaries clearly indicate that almost all the distributaries the supply take place based on similar pattern, suggesting that there is no functional difference among the distributaries in different parts of the system.

95

Table 5.2 Monthly average RWS of selected distributaries. Distributary

Oct

Nov

Dec

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Average

Yaqubi

2.41

4.05

4.90

0.25

0.35

1.47

1.57

1.62

1.51

2.19

1.77

1.27

1.95

Gumbt-II

3.02

4.53

5.69

0.25

0.35

1.44

2.31

2.24

1.92

2.19

1.79

1.66

2.28

Qasim-II

2.73

3.94

4.24

0.25

0.34

1.85

1.68

1.75

1.68

1.78

1.76

1.40

1.95

Toru

2.83

4.10

5.09

0.26

0.35

2.18

1.81

1.32

1.61

2.32

1.79

1.44

2.09

Pirsabak

2.43

4.12

5.67

0.26

0.34

2.08

1.60

1.65

1.40

2.23

1.84

1.28

2.08

Chowki

2.23

3.80

5.19

0.25

0.36

2.01

1.69

1.95

1.64

2.42

1.92

1.23

2.06

The Fig. 5.1 to 5.6 indicate that at the beginning of the Winter season RWS is more than 2.00, thus permitting farmers to irrigate only day time and divert irrigation water to drain during the night to avoid night irrigation. These results indicate that moderate efforts are needed to bring the water supply closer to crop water requirements by involving FOs in operation of irrigation system. The continuous high RWS may ultimately cause waterlogging conditions.

5.3

DELIVERY PERFORMANCE RATIO AND RELIABILITY

The delivery performance ratios (DPR) for the selected distributaries were calculated and the results are shown in Figures 5.7 to 5.12. Monthly average DPRs are given in Table 5.3. The average DPR varied from 0.78 to 0.83 during summer and 0.63 to 0.73 during winter months.

96

0.50

1.00

0.40

0.80

0.30

0.60

DPR

0.20

CV T (DPR)

0.40

CVT(DPR)

Delivery Performance Ratio

1.20

0.10

0.20

Sept III

Sept I

Aug II

July III

July I

June II

May III

May I

April II

March III

Dec III

Dec I

Nov II

Oct III

0.00 Oct I

0.00

Fig. 5.7 Delivery performance ratio and CVT(DPR) of Yaqubi Distributary. B

B

0.30

1.00 0.80

0.20 CV T(DPR)

0.60

DPR

0.40

0.10

CVT(DPR)

Delivery Performance Ratio

1.20

0.20

Sept III

Sept I

Aug II

July III

July I

June II

May III

May I

April II

March III

Dec III

Dec I

Nov II

Oct III

0.00 Oct I

0.00

Fig. 5.8 Delivery performance ratio and CVT(DPR) of Gumbad-II Distributary. B

97

B

0.70

1.00

0.60

DPR

0.50 0.40

CVT(DPR)

0.60

0.30 0.40

CVT(DPR)

0.80

0.20

Sept III

Sept I

Aug II

July III

July I

June II

May III

May I

April II

March III

Dec III

0.00 Dec I

0.00 Nov II

0.10

Oct III

0.20

Oct I

Delivery Performance Ratio

1.20

Fig. 5.9 Delivery performance ratio and CVT(DPR) of Qasim-II Distributary. B

B

0.60 0.50

CVT(DPR)

0.80

0.40

0.60

0.30

DPR

Sept III

Sept I

Aug II

July III

July I

June II

May III

May I

April II

0.00 March III

0.00 Dec III

0.10

Dec I

0.20

Nov II

0.20

Oct III

0.40

CVT(DPR)

1.00

Oct I

Delivery Performance Ratio

1.20

Fig. 5.10 Delivery performance ratio and CVT(DPR) of Toru Distributary. B

98

B

0.40

1.00 0.30 0.80

CV T(DPR)

0.60

0.20

DPR

0.40

CVT(DPR)

Delivery Performance Ratio

1.20

0.10 0.20

Sept III

Sept I

Aug II

July III

July I

June II

May III

May I

April II

March III

Dec III

Dec I

Nov II

Oct III

0.00 Oct I

0.00

Fig. 5.11 Delivery performance ratio and CVT(DPR) of Pirsabak Distributary. B

B

0.50

1.00

0.40

0.80

0.30

0.60

CVT(DPR)

DPR

0.40

0.20

CVT(DPR)

Delivery Performance Ratio

1.20

0.10

0.20

Sept III

Sept I

Aug II

July III

July I

June II

May III

May I

April II

March III

Dec III

Dec I

Nov II

Oct III

0.00 Oct I

0.00

Fig.5.12 Delivery performance ratio and CVT(DPR) of Chowki Distributary. B

99

B

It is evident from the figures that all the distributaries irrespective of their locations are drawing approximately 70-80 percent of their design discharges. The traditional operation mode of running the main canal at or near the full supply level and making necessary reduction in deliveries during the period of heavy rainfall continued more or less unchanged. Reasonable equity of water distribution at tertiary level is achieved during operation of irrigation system except in January and February when system was closed for annual maintenance.

The DPR values for March and April are low because after the annual closure, the inflow is increased gradually according to the principles of operating alluvial channels (PID 1997). In fact the irrigation system of Maira Branch is combination of downstream and upstream control, which provides stable discharges to selected distributaries.

If the discharge is more or less constant, than there will be low coefficient of variation (CVT(DPR)), this implies that the farmers are confident abut the B

B

discharges they can expect.

The Low CVT(DPR) mean that discharge B

B

tomorrow will be more or less same as today, allowing flexibility to farmers to plan their irrigation application and water distribution among themselves and to different fields. The temporal CVT (DPR) is low i.e. < 0.2 are considered satisfactory and B

B

indicate that there is no communication problems between the gate operators.

100

The Figures 5.7 to 5.12 shows that CVT(DPR) is in acceptable range during B

B

October to December indicating that there is not much fluctuation in water deliveries and the irrigation supplies are reliable and dependable in all the distributaries (Table 5.4).

The CVT(DPR) are high in Toru Distributary in November, December and July B

B

because of the general tendency is to reduce the inflows in the irrigation system due to heavy rains. The analyses of data indicate that high CVT(DPR) is B

B

associated with closure of irrigation canal from Amandrah head work in response to heavy rainfall.

The variations in discharges are only due to intervention of SCAWB and reflect the managerial operational response but due to increase in water allowance, there is no significant response and initiative from the downstream of the distributaries. This indicates that farmers’ input in canal operation is minimal due to physical improvements that result in increased water availability.

Table 5.3 Average monthly DPR of selected distributaries. Distributary

Oct

Nov

Dec

Mar

Apr

Yaqubi

0.76 0.78 0.75 0.27 0.62 0.79 0.84 0.82 0.81 0.79

0.72

Gumbt-II

0.81 0.73 0.74 0.32 0.73 0.87 0.87 0.70 0.69 0.88

0.73

Qasim-II

0.91 0.79 0.66 0.39 0.70 0.93 1.02 0.66 0.80 0.89

0.78

Toru

0.84 0.72 0.72 0.41 0.67 0.64 0.89 0.86 0.76 0.84

0.74

Pirsabak

0.79 0.79 0.83 0.47 0.68 0.89 0.85 0.88 0.81 0.78

0.78

Chowki

0.78 0.62 0.82 0.34 0.60 0.88 0.84 0.86 0.81 0.77

0.73

101

May

Jun

Jul

Aug

Sep

Average

Table 5.4 Reliability of irrigation supplies of selected distributaries. Distributary

Oct

Yaqubi

0.08 0.07 0.04 0.02 0.16 0.11 0.11 0.31 0.09 0.08

0.12

Gumbt-II

0.11 0.10 0.02 0.02 0.21 0.08

0.24 0.13 0.14

0.12

Qasim-II

0.20 0.15 0.18 0.06 0.17 0.11 0.11 0.47 0.22 0.14

0.18

Toru

0.05 0.30 0.36 0.07 0.29 0.36 0.24 0.30 0.21 0.08

0.23

Pirsabak

0.09 0.09 0.07 0.05 0.22 0.10 0.07 0.14 0.06 0.08

0.10

Chowki

0.06 0.08 0.05 0.03 0.27 0.10 0.07 0.09 0.10 0.07

0.09

5.4

Nov

Dec

Mar

Apr

May

Jun

0.1

Jul

Aug

Sep

Average

CROP YIELDS

The yields of major crops were determined from the field data collected through the farmers’ interviews of the Chowki and Pirsabak Distributaries (Table 5.5 and 5.6). Average yield of maize, tobacco, sugarcane and wheat was 1.7, 1.5, 40 and 3.5 tons per ha respectively on the Chowki Distributary whereas the yield of the same crops were 1.5, 2, 38 and 3.3 tons per ha respectively at the other Pirsabak Distributary after the IMT. There is significant increase in yield of maize (40 percent), sugarcane (55 percent) and wheat (43 percent).

The

increase in yield may be due to increase in water supply due to modernization of the irrigation systems. Table 5.5 Pre and post IMT crop yields (ton.ha-1) of Chowki Distributary Average Percentage Location Head Middle Tail Pre IMT Post IMT yield Yield Sample Size (35) (68) (68) (171) increase P

Maize Tobacco Sugarcane Wheat

1.9 1.5 39.0 3.6

1.7 1.7 44.0 3.6

1.6 1.5 38.0 3.4

102

P

1.7 1.6 40.3 3.5

1.2 1.6 26.0 2.5

41.0 0.0 55.0 40.0

Table 5.6 Pre and post IMT crop yields (ton.ha-1) of Pirsabak Distributary Percentage Average Location Head Middle Tail Pre IMT yield Post IMT Yield increase Sample Size (40) (80) (80) (200) P

Maize Tobacco Sugarcane Wheat

5.5

1.6 2.0 40.0 3.5

1.8 2.5 46.0 3.3

1.1 1.8 30.0 3.2

P

1.5 2.1 38.7 3.3

1.2 1.6 26.0 2.5

50.0 31.0 48.0 32.0

COST RECOVERY

The revenue expenditure gap of the irrigation system in Pakistan has been consistently increasing at a relatively high rate over the past many years. Bhatti (1995) considered the social factors i.e. corruption-cum-political interference for increase in the expenditure and attributed it to growing illicit practices well documented by Wade (1982). After IMT, FOs collects the assessed ISF (Abiana) from the irrigators and retained 40 percent of the recovered amount for operation and maintenance of the irrigation system, while 60 percent is paid to the Swat Canal Area Water Board (SCAWB).

In Pakistan Irrigation Service Fee (ISF) is levied on the type of the crops, grown on the basis of area sown under each crop. Table 5.7 indicates that all the FOs performed well during the Ist year (2004-05) of IMT and recovered 60 percent of the assessed ISF except Toru and Pirsabak distributaries. But during 2005-06, the ISF collection was very low (Tables 5.8 and 5.9). FOs has legal power to penalizes defaulter by cutting or suspension of the irrigation supply if any farmer

is defaulter for two seasons but due to social setup such actions are difficult to

103

initiate by the FOs. If existing situation prevails, the self sufficiency of Toru and Pirsabak distributaries may be threaten. Awareness campaign to motivate the farmers for paying the irrigation charges may be helpful to encounter the situation.

Analysis of net income received from different crop production per hectare revealed that sugarcane is the most profitable crop followed by the wheat. The existing cropping intensity of sugarcane and wheat is 30 and 50 percent whereas ISF (Abiana) for both the crops are Rs. 3084 and Rs. 459 respectively (Appendix Tables XIII and XIV). The smallest land holding in the area is 1.5 ha. Apparently, there is no financial constraint and hindrance in paying the ISF (Abiana). Thus it can be argued that farmers are not willing to pay the ISF (Abiana).

Table 5.7 ISF assessed and recovered before IMT (million Rupees). Season

Rabi

Year

Toru

Chowki

Qasim-II

Pirsabak

Gumbad-II

Yaqubi

2001-02

0.209

1.19

0.17

0.792

0.174

0.247

2002

0.581

1.446

0.428

0.126

0.405

0.821

2002-03

0.208

0.954

0.159

0.074

0.172

0.25

2003

0.496

1.759

0.427

1.257

0.262

0.891

2003-04

0.193

0.899

0.148

0.769

0.168

0.244

Total

1.687

6.248

1.332

3.018

1.181

2.453

Recovered

1.043

4.738

0.925

2.294

0.874

1.739

Recovery (%)

61.83

75.83

69.44

76.01

74.01

70.89

Kharif Rabi Kharif Rabi

104

Table 5.8 ISF (Abiana) assessed after IMT (Million Rs.). Year

Toru

Chowki

Qasim-II

Pirsabak

Gumbad-II

Yaqubi

2004-05

0.791

2.591

0.584

2.07

0.690

1.143

2005-06

0.662

2.941

0.638

2.023

0.679

1.176

2006-07

0.722

2.673

0.617

2.124

0.662

0.839

2007

0.546

1.841

0.450

1.535

0.563

0.97

Total Assessed

2.721

10.046

2.289

7.752

2.594

4.128

Table 5.9 ISF (Abiana) recovered after IMT (Million Rs.). Year

Toru

Chowki

Qasim-II

Pirsabak

Gumbad-II

Yaqubi

2004-05

0.273

1.914

0.494

0.375

0.441

0.736

2005-06

0.388

1.687

0.377

0.265

0.257

0.396

2006-07

0.273

1.308

0.320

0.140

0.254

0.254

2007

0.162

0.508

0.035

0.040

0.165

0.064

Total Recovered

1.096

5.417

1.226

0.820

1.117

1.450

Recovered (%)

40.28

53.92

53.56

10.58

43.06

35.13

5.6

ACTUAL STRATEGIES FOR OPERATION OF IRRIGATION SYSTEM

5.6.1 Current Operation of Chowki Distributary Chowki Distributary is managed by FOs in consultation with SCAWB. The distributary falls in the Jagannath sub division jurisdiction. SDO Jagannath, with consultation of FOs assess the crop water demand based on cropping pattern and intensity. By adding full supply discharge of all offtaking distributaries, he workout the indent. The accumulated requirements of all the distributaries are communicated to the Water Dispatch officer of Regulation Cell Gohati, Swabi for onward submission to SCAWB for receiving water share from FIDA.

105

Releases are governed by the indents, availability of water and share of the canal. Indents are normally fulfilled if water is available. Unilateral procedures were practiced before the IMT and under British colonial period. Water demands were assessed by ‘patwaries’ and operational staff of the irrigation department based on the patwaries assessment of irrigated area and cropping pattern.

The distributary operations regulate the whole delivery system and especially play key role in farm operation. Fig. 5.13 shows that distributary head regulator is not operated in response to the demand. During the rainfall events and period of low demand, i.e. Mid March-April and in November, the farmers completely or partially closed their offtakes, without communications with FOs which caused overtopping of the tail as there is no escape in the distributary, and the only choice left with FOs is to reduce discharge at the head. 3.5 3.0

3 -1

Discahrge (m s )

2.5 Design Discharge

2.0 1.5 1.0 Supplied Discharges

Demand Discharges

0.5

Demand and supply pattern of Chowki Distributary.

106

31-Dec

3-Dec

17-Dec

5-Nov

19-Nov

22-Oct

8-Oct

24-Sep

10-Sep

27-Aug

30-Jul

13-Aug

2-Jul

16-Jul

18-Jun

4-Jun

7-May

21-May

9-Apr

23-Apr

26-Mar

12-Mar

26-Feb

29-Jan

12-Feb

1-Jan

Fig. 5.13

15-Jan

0.0

Closing of main canal system is directly linked with heavy rainfall. The AWB and Regulation Cell decide to close the entire system from the head work, if rainfall of 70-100 mm occurred during pervious week. Response is immediate if single heavy rainfall event falls.

After IMT and modernization of USC irrigation system, the intension is to operate the system more in a demand responsive mode, so that irrigation supply better matches to the actual demand. This type of operation can be achieved through irrigation management information system (IMIS) and required the knowledge of the potential demand of irrigation water determined by evapotranspiration, cropping intensity and cropping pattern.

In post IMT adequacy becomes a significant criterion. In the demand responsive systems the pattern of irrigation deliveries has significant relationship to evapotranspiration. Irrigation deliveries were calculated by converting the discharges into equivalent depths of irrigation application. This approach gives close look to the distributary operation and utility of the irrigation water by the farmers.

Fig. 5.14 reveals that the water deliveries pattern is not related to evapotranspiration. In the beginning of the year, the irrigation system was closed due to annual maintenance.

From 15th March till to the 30th June P

P

P

P

irrigation deliveries exceed the evapotranspiration i.e. exceeded the demand. From July to September the deliveries were close to evapotranspiration.

107

However, after September the evapotranspiration fell below 5 mm day-1 while irrigation deliveries were maintained at their normal high levels.

The analysis shows that during post IMT, there is no significant evidence of operation of the distributary head regulator in response to increased water deliveries. The traditional mode of running the distributary at or near the full

14.0 12.0 10.0

ETo

Irrigation Deliveries 8.0 6.0 4.0 2.0

Dec II

Nov III

Nov I

Oct II

Sept III

Sept I

Aug II

July III

July I

June II

May III

May I

April II

March III

March I

Feb II

Jan III

0.0 Jan I

-1

Irrigation Deliveries (mm day per CCA)

supply level was practiced except after the heavy rainfall.

Fig. 5.14 Irrigation water deliveries and ETo at Chowki Distributary. The existing operation pattern suggests that there is considerable potential for development of effective responsive operation of the Chowki Distributary. During the canal closure period the crop use water from the moisture stored in root zone. The root zone moisture is supplemented by the rainfall during

108

January, February. Also during this period evapotranspiration demand of the crop is less because most of the crops are in early growth stages.

5.7

CALIBRATION AND VALIDATION OF SIC MODEL

Model calibration is the processes of comparing the model prediction for a given set of conditions with observed data for the same condition. A model is considered to be successfully calibrated when the simulated values match with the observed values. Validation involves testing the model predictive capabilities. Validation requires comparing model prediction with information other than that used in calibrating the model. It involves checking the model results against observed data and adjusting parameters until result fall within the acceptable range of error. The statistical evaluation is essential and provides insight into model performance i.e.

whether the predicted or simulated

discharges and water levels are consistent and agree reasonably well with the observed values.

The calibration period is the portion of the period of study and is selected because it represents the operation in the average sense. The data used for calibration of the model in steady state condition consist of a set of water levels at crests of bifurcators, trifurcators and open flumes for 100, 80 , 70 and 60 percent of design discharges on 11th and 18th April, 28th April to 30th April, 4th and 6th June, 12th and P

P

P

P

P

P

P

P

P

P

P

P

P

P

26th September,2007 respectively. Values of the Manning roughness coefficient P

P

used in model calibration are given in Table 5.10. After calibration of the model for typical situations observed in the field, the model was validated with another data set to recheck the results simulated by the model.

109

The coefficient of discharge for open flume in calibration and validation of SIC model was used 0.94 0 . 50 , where H1 is ⎝ L ⎠ total upstream energy head over the crest (Bos, 1989 § P: 40). Because the influence of the stream line curvature become significant, and the structure acts as a short crested weir. For the practical purpose, a short crested weir with rectangular control section has head discharge (m3s-1) following head discharge equation, where h1 upstream head (m) over the crest (Bos, 1989 § P: 180-184).

⎡2 0.5 ⎤ 1.5 Q = ⎢ ∗ (2 g ) ⎥ ∗ (C d * C v ) ∗ ( Bc ∗ h1 ) .......................................................... (E-1) 3 ⎣ ⎦

187

The simplified head discharge equation for determination of discharge of Crump’s weir is as follow

Q = 1.98 ∗ Bc ∗ h1 ........................................................................................... (E-2) 1.5

Limits of Application ‰ Over the selected range of the ratio, being, ⎛⎜ h1 ⎞⎟ < 3 , the discharge ⎝ p1 ⎠ coefficient is a function of the dimensionless ratio ⎛⎜ h1 ⎞⎟ . Where p1 is ⎝ p1 ⎠ height of crest above approach channel bed. ‰ The height of the weir crest should not be less than 0.06 m above the approach channel bottom (p1< 0.06 m). ‰ To reduce the influence of boundary layer effects at the sides of the weir, the breadth of the weir be should not be less than 0.30 m and the

B ratio ⎛⎜ c ⎞⎟ should not be less than 2.0; Where H is total energy head ⎝ H⎠ (m) above crest. ‰ It comprises a weir with a 1:2 sloping upstream glacis and 1:5 slopes facing on downstream. The slope has advantage, that the location of hydraulic jump is more stable allowing a fairly high and constant modular limit ⎛⎜ H 2 ⎞⎟ of between 0.73 and 0.77. Where H1 and H2 total ⎜ H ⎟ ⎝ 1⎠ energy head at upstream and downstream head over crest.

188

E-2 Detail Drawing of Single Bifurcators.

Fig. E-2 Detail drawing of single bifurcators.

Fig. E-3 Section at A-A of Crump’s weir in irrigation network.

189

E-4 Field test of selected Crump weir. Description

RD

unit

5930

6185

7622

1048

919

Water Level

El.B

FSL

m

323.15

321.99

311.16

306.73

311.53

Upstream Bed Level

El.C

u/s Bed Level

m

322.47

321.27

310.68

306.09

311.02

Crest Level

El.F

Crest

m

322.65

321.54

310.95

306.37

311.35

El.I

d/s W.L.

m

323.95

321.79

310.94

308.53

311.18

El.G

d/s Bed Level

m

322.16

321.03

310.33

305.8

310.66

El.F- El.C

p

m

0.18

0.27

0.27

0.28

0.33

El.B- El.F

h

m

0.50

0.45

0.21

0.36

0.18

El.B- El.C

Hu

m

0.68

0.72

0.48

0.64

0.51

El.I - El.G

Hd

m

0.52

0.55

0.36

0.49

0.39

Bc

mm

1600

1800

1630

2500

1250

b

m

1.60

1.80

1.63

2.50

1.25

h/p

2.78

1.67

0.78

1.29

0.55

Bc/h

3.20

4.00

7.76

6.94

6.94

Downstream Bed Level

d/s Flow Condition

190

Modular Flow Downstream

E-5 Drawing and Description of Double Bifurcators

Fig. E-5 Drawing of double bifurcators. The relation between the heads at double bifurcators is determined using continuity equation between two points and following relation is obtained. Let F1 be the width of head Crump’s weir and F7 and F8 are width of crump’s weir at double bifurcator point.

1 . 98 * F 1 * H 11 . 5 = 1 . 98 * (F 6 + F 7 ) * H ∴ H

2

⎛ F1 ⎞ ⎟⎟ = ⎜⎜ ⎝ F 6+ F7 ⎠

2/3

* H1

1 .5 2

⎫ ⎪ .....................................................(E-3) ⎬ ⎪ ⎭

Generally the following relation is used for determination of the bifurcators’ discharges.

H 2 = 0 . 542 * H 1 ......................................................................................... (E-4)

191

E-6 Irrigation Deliveries to Qasim-II, Gumbad-II and Yaqubi Distributaries.

Fig. E-6 Irrigation deliveries to Qasim-II Gumbad-II and Yaqubi distributaries.

E-7 Irrigation Deliveries to Chowki, Toru and Pirsabak Distributaries.

Fig. E-7 Irrigation deliveries to Chowki, Toru and Pirsabak distributaries.

192

JAVAID AKHTAR TARIQ Candidate for the Degree of Doctor of Philosophy

Dissertation:

Improving Operational Performance and Management of Canal Irrigation System Using Hydraulic Modeling.

Major Field: Water Resources Engineering Biographical Information: Personal Data:

Born in Peshawar, Pakistan,1st April, 1959; son of Abdur Rahim Khan.

Education: Received Bachelor of Science (B.Sc.) from Edwards College, Peshawar in 1979, Bachelor of Science in Agricultural Engineering (1984) from Department of Agricultural Engineering and Master of Science in Water Resources Engineering (1988), from Department of Civil Engineering, NWFP University of Engineering and Technology, Peshawar. Awarded six months fellowship by Government of The Netherlands in Irrigation Management (1991) at Department of Irrigation and Civil Engineering, Wageningen University, The Netherlands. Completed 5th Course (1994) on “Appropriate Modernization and Management of Irrigation System” Organized by International Institute for Infrastructures, Hydraulic and Environmental Engineering, (IHE), The Netherlands. Completed the requirements for the Doctor of Philosophy degree in Water Resources Engineering at Centre of Excellence in Water Resources Engineering (CEWRE), University of Engineering and Technology, Lahore in 2010. Professional Experience: Presently Assistant Professor, Department of Water Management; taught irrigation management courses at department and conducted national and international trainings in irrigation water management. Involved in research on “Development of standards and specification of water management at farm level: Low cost lining method and optimum design criteria for watercourse in NWFP” during 1987-88, “Impact of rehabilitation on irrigation water distribution in Lower Swat Canal irrigation system” during 1992-93 and “Management of small scale waterlogging and salinity problems in major irrigated areas of NWFP” during 2001-04. More than twenty students undertook research under my supervision for their M.Sc. (H) thesis on matching irrigation supply and demand, reducing tertiary level conveyance losses, efficiency of irrigation application methods, interaction of between the main irrigation and tertiary water management systems and warabandi dynamics and organization of water management.

193