Foreword 5
Preface 7
Acknowledgment 9
Contents 10
1 Water Conveyance Loss and Designing Conveyance System 23
1.1 Water Conveyance Loss 24
1.1.1 Definition of Seepage 24
1.1.2 Factors Affecting Seepage 24
1.1.3 Expression of Seepage 25
1.1.4 Measurement of Seepage 26
1.1.4.1 Ponding Method 26
1.1.4.2 Inflow--Outflow Method 27
1.1.4.3 Seepage Meter Method 28
1.1.5 Estimation of Average Conveyance Loss in a Command Area 29
1.1.6 Reduction of Seepage 30
1.1.6.1 Physical Method 30
1.1.6.2 Chemical Method 30
1.1.6.3 Biological Method 30
1.1.7 Lining for Reducing Seepage Loss 30
1.1.7.1 Benefits of Lining 30
1.1.7.2 The Decision on Canal Lining 31
1.1.7.3 Lining Materials 31
1.2 Designing Open Irrigation Channel 32
1.2.1 Irrigation Channel and Open Channel Flow 32
1.2.2 Definition Sketch of an Open Channel Section 32
1.2.3 Considerations in Channel Design 33
1.2.3.1 Channel Geometry 33
1.2.3.2 Capacity Requirements 33
1.2.3.3 Permissible Velocity/Velocity Limitations 33
1.2.3.4 Freeboard 34
1.2.3.5 Water Surface Elevations 34
1.2.3.6 Side Slopes 34
1.2.4 Calculation of Velocity of Flow in Open Channel 34
1.2.4.1 Chezy's Equation 34
1.2.4.2 Manning's Equation 35
1.2.4.3 Manning''s ''N'' Values 35
1.2.5 Hydraulic Design of Open Irrigation Channel 36
1.2.5.1 Condition for Maximum Discharge Through a Channel of Rectangular Section 36
1.2.5.2 Condition for Maximum Discharge Through a Channel of Trapezoidal Section 37
1.2.6 Sample Examples on Irrigation Channel Design 40
Example 1.1 40
Solution 40
Example 1.2 40
Solution 40
Example 1.3 42
Solution 42
1.3 Designing Pipe for Irrigation Water Flow 43
1.3.1 Fundamental Theories of Water Flow Through Pipe 43
1.3.1.1 Theories of Physics 43
1.3.1.2 Theories of Hydraulics and Fluid Flow 44
1.3.2 Water Pressure -- Static and Dynamic Head 45
1.3.2.1 Static and Dynamic Head 46
1.3.2.2 Pressure Distribution in a Water Column/Tank 46
1.3.3 Hydraulic and Energy Grade Line for Pipe Flow 47
1.3.4 Types of Flow in Pipe -- Reynolds Number 47
1.3.5 Velocity Profile of Pipe Flow 48
1.3.6 Head Loss in Pipe Flow and Its Calculation 48
1.3.6.1 Causes and Components of Head Loss 48
1.3.6.2 Factors Affecting Head Loss 49
1.3.6.3 Different Head Loss Equations 49
1.3.6.4 Calculation of Minor Loss 52
1.3.6.5 Minimizing Head Loss in Pipe 52
1.3.6.6 Sample Workout Problem 53
Example 1.4 53
Solution 53
1.3.7 Designing Pipe Size for Irrigation Water Flow 53
1.3.8 Sample Workout Problems 54
Example 1.5 54
Solution 54
1.4 Relevant Journals 54
1.4 Questions 55
References 56
2 Water Application Methods 57
2.1 General Perspectives of Water Application 58
2.2 Classification of Water Application Methods 58
2.3 Description of Common Methods of Irrigation 60
2.3.1 Border Irrigation 60
2.3.1.1 Concept and Features 60
2.3.1.2 Suitability, Capabilities, and Limitations of Border Method 61
2.3.2 Basin Irrigation 62
2.3.2.1 Concept and Characteristics 62
2.3.2.2 Suitabilities and Limitations of Basin Irrigation Method 63
2.3.3 Furrow Irrigation 65
2.3.3.1 Concepts and Features 65
2.3.3.2 Suitability and Limitations 66
2.3.4 Sprinkler Irrigation Systems 68
2.3.4.1 Concept and Features 68
2.3.4.2 Types of Sprinkler Systems 69
2.3.4.3 Capabilities and Limitations of Sprinkler System 72
2.3.4.4 Choosing a Sprinkler Type 74
2.3.5 Drip Irrigation 74
2.3.5.1 Concept and Features 74
2.3.5.2 Suitabilities, Capabilities, and Limitations 75
2.3.6 Other Forms of Irrigation 76
2.4 Selection of Irrigation Method 78
2.4.1 Factors Affecting Selection of an Irrigation Method 78
2.4.2 Selection Procedure 85
Relevant Journals 85
Questions 85
3 Irrigation System Designing 86
3.1 Some Common Issues in Surface Irrigation System Designing 87
3.1.1 Design Principle of Surface Irrigation System 87
3.1.2 Variables in Surface Irrigation System 88
3.1.3 Hydraulics in Surface Irrigation System 88
3.2 Border Irrigation System Design 89
3.2.1 Definition of Relevant Terminologies 89
3.2.2 General Overview and Considerations 90
3.2.3 Factors Affecting Border Performance and Design 91
3.2.3.1 Soil Type and Infiltration Characteristics 91
3.2.3.2 Border Inflows 91
3.2.3.3 Longitudinal Slope 91
3.2.3.4 Irrigation Depth 91
3.2.4 Design Parameters 91
3.2.5 Design Approaches and Procedures for Border 92
3.2.5.1 Approaches 92
3.2.5.2 Empirical Models for Designing Border Irrigation System 92
3.2.6 Sample Workout Problems 94
Example 3.1 94
Solution 94
Example 3.2 95
Solution 95
Example 3.3 96
Solution 96
Example 3.4 96
Solution 97
3.2.7 Simulation Modeling for Border Design 97
3.2.8 Existing Software Tools/Models for Border Irrigation Design and Analysis 98
3.2.8.1 BORDEV 98
3.2.8.2 SIRMOD 98
3.2.8.3 SIRMOD II 98
3.2.8.4 WinSRFR 99
3.2.8.5 SADREG 99
3.2.9 General Guidelines for Border 100
3.3 Basin Irrigation Design 100
3.3.1 Factors Affecting Basin Performance and Design 100
3.3.1.1 Flow Rate 101
3.3.1.2 Soil Type 101
3.3.1.3 Basin Longitudinal Slope 101
3.3.1.4 Aspect Ratio 101
3.3.1.5 Local Surface Micro-topography 101
3.3.1.6 Number of Check Bank Outlets 102
3.3.1.7 Elevation Difference (Vertical Interval) Between Adjacent Basins 102
3.3.1.8 Irrigation Depth 102
3.3.2 Hydraulics in Basin Irrigation System 102
3.3.3 Simulation Modeling for Basin Design 103
3.3.3.1 Hydrodynamic Model 103
3.3.3.2 Zero-Inertia Model 104
3.3.3.3 Other Approaches 104
3.3.4 Existing Models for Basin Irrigation Design 105
3.3.4.1 COBASIM 105
3.3.4.2 BASCAD 105
3.3.4.3 SIRMOD, WinSRFR, SADREG 105
3.4 Furrow Irrigation System Design 105
3.4.1 Hydraulics of Furrow Irrigation System 106
3.4.2 Mathematical Description of Water Flow in Furrow Irrigation System 107
3.4.2.1 Unsteady Gradually Varied Surface Water Flow 107
3.4.3 Some Relevant Terminologies 108
3.4.3.1 Intake Rate 108
3.4.3.2 Infiltration Opportunity Time 109
3.4.3.3 Distribution Uniformity 109
3.4.3.4 Time Ratio 109
3.4.3.5 Cutoff Ratio or Advance Ratio 110
3.4.3.6 Irrigation Set Time 110
3.4.3.7 Advance Rate 110
3.4.3.8 Advance Function 111
3.4.3.9 Surge Flow/Irrigation 111
3.4.3.10 Gross Water Needed for Furrows 111
3.4.4 Factors Affecting Performance of Furrow Irrigation System 111
3.4.4.1 Soil Characteristics 111
3.4.4.2 Stream Size 111
3.4.4.3 Length of Run 112
3.4.4.4 Cutoff Ratio 112
3.4.4.5 Tailwater Reuse 112
3.4.4.6 Wetted Perimeter 112
3.4.5 Management Controllable Variables and Design Variables 112
3.4.5.1 Management Controllable Variables 112
3.4.5.2 Design Variables 112
3.4.6 Furrow Design Considerations 113
3.4.7 Modeling of Furrow Irrigation System 113
3.4.7.1 Theoretical Considerations 113
3.4.7.2 Simulation of Furrow Design Variables 114
3.4.8 General Guideline/Thumb Rule for Furrow Design 115
3.4.8.1 Furrow Length 115
3.4.8.2 Slope 115
3.4.8.3 Stream Size/Flow Rate 116
3.4.8.4 Furrow Shape 116
3.4.8.5 Spacing of Furrow 116
3.4.9 Estimation of Average Depth of Flow from Volume Balance 116
3.4.10 Suggestions for Improving Furrow Irrigations 117
3.4.11 Furrow Irrigation Models 117
3.4.11.1 FURDEV 117
3.4.11.2 SIRMOD, SIRMODII, WinSRFR 118
3.4.12 Sample Worked Out Problems 118
Example 3.5 118
Solution 118
Example 3.6 118
Solution 119
Example 3.7 119
Solution 119
3.5 Design of Sprinkler System 119
3.5.1 Design Aspects 119
3.5.2 Theoretical Aspects in Sprinkler System 120
3.5.2.1 Water Distribution Pattern 120
3.5.2.2 Factors to Be Considered in Sprinkler Design 120
3.5.2.3 Definition of Some Relevant Terminologies 121
3.5.3 Sprinkler Design 122
3.5.3.1 Considerations in Sprinkler Design 122
3.5.3.2 Design Principles 122
3.5.3.3 Design Steps and Procedures 123
3.5.3.4 Sample Workout Problems 125
Relevant Journals 127
Relevant FAO Papers/Reports 128
Questions 128
Common in Surface Irrigation 128
Border Irrigation 128
Basin Irrigation 129
Furrow Irrigation 129
Sprinkler Irrigation 129
References 130
4 Performance Evaluation of Irrigation Projects 132
4.1 Irrigation Efficiencies 133
4.1.1 Application Efficiency 133
4.1.2 Storage Efficiency/Water Requirement Efficiency 135
4.1.3 Irrigation Uniformity 135
4.1.3.1 Uniformity Coefficient 136
4.1.4 Low-Quarter Distribution Uniformity (or Distribution Uniformity) 136
4.2 Performance Evaluation 137
4.2.1 Concept, Objective, and Purpose of Performance Evaluation 137
4.2.1.1 Concept 137
4.2.1.2 Objectives 137
4.2.1.3 Purposes 138
4.2.1.4 Benefits of Evaluation 138
4.2.2 Factors Affecting Irrigation Performance 138
4.2.3 Performance Indices or Indicators 139
4.2.3.1 Engineering Indicators 139
4.2.3.2 Field Water Use Indicators 140
4.2.3.3 Crop and Water Productivity and Acreage 140
4.2.3.4 Socioeconomic Indicators 140
4.2.4 Description of Different Indicators 141
4.2.4.1 Engineering Indicators 141
4.2.4.2 Field Water Use Indicators 144
4.2.4.3 Crop and Water Productivity and Acreage 145
4.2.4.4 Socioeconomic Indicators 147
4.2.5 Performance Evaluation Procedure 147
4.2.5.1 Steps and Techniques 147
4.2.5.2 Queries That Should Be Answered 148
4.2.5.3 Ideal Condition for Evaluation of Irrigation System 149
4.2.6 Performance Evaluation Under Specific Irrigation System 149
4.2.6.1 Pumping Plant Evaluation 149
4.2.6.2 Border Irrigation Evaluation 149
4.2.6.3 Basin Irrigation Evaluation 151
4.2.6.4 Furrow Irrigation Evaluation 151
4.2.6.5 Sprinkler Irrigation Evaluation 152
4.2.6.6 Drip/Micro-irrigation Evaluation 155
4.2.7 Improving Performance of Irrigation System 155
Relevant Journals 158
Relevant FAO Papers/Reports 158
Questions 158
References 158
5 Water Resources Management 160
5.1 Concept, Perspective, and Objective of Water Resources Management 161
5.1.1 Concept of Management 161
5.1.2 Water and the Environment 162
5.1.3 Increasing Competition in Water Resource 162
5.1.4 Water As an Economic Good 163
5.1.5 Purposes and Goals of Water Resources Management 164
5.1.6 Fundamental Aspects of Water Resources Management 165
5.2 Estimation of Demand and Supply of Water 165
5.2.1 Demand Estimation 165
5.2.1.1 Demand for Domestic, Industrial, and Commercial Uses 166
5.2.1.2 Irrigation Demand 166
5.2.1.3 Nonirrigated Evaporative Demand 167
5.2.1.4 In-Stream Demand 167
5.2.2 Estimation of Potential Supply of Water 167
5.2.2.1 Surface Water Resource 167
5.2.2.2 Groundwater Resource 168
5.2.3 Issues of Groundwater Development in Saline/Coastal Areas 169
5.2.4 Environmental Flow Assessment 169
5.2.4.1 Concept of Environmental Flow 169
5.2.4.2 Methods of Environmental Flow Assessment 170
5.3 Strategies for Water Resources Management 171
5.3.1 Demand Side Management 171
5.3.1.1 Concept 171
5.3.1.2 Different Approaches of Demand Management 171
5.3.1.3 Obstacles to Implement Demand Management 180
5.3.2 Supply Side Management 182
5.3.2.1 Approaches of Supply Management 182
5.3.2.2 Description of Different Approaches 183
5.3.2.3 Implementation of Supply Management Options 190
5.3.3 Integrated Water Resources Management 191
5.3.3.1 Meaning of Integrated Water Resources Management 191
5.3.3.2 Approaches, Barriers, and Problems of Integrated Water Resources Management 192
5.4 Sustainability Issues in Water Resource Management 194
5.4.1 Concept of Sustainability 194
5.4.2 Scales of Sustainability 196
5.4.3 Achieving Sustainability 196
5.4.4 Strategies to Achieve Sustainability 198
5.4.4.1 Integrated Management of Water 198
5.4.4.2 Participation of Users and Stakeholders 199
5.4.4.3 Environmental Protection 199
5.4.4.4 Research into the Impacts of Water Policy 199
5.4.4.5 Capacity Building for Integrated Management 199
5.5 Conflicts in Water Resources Management 199
5.5.1 Meaning of Conflict 199
5.5.2 Water Conflicts in the Integrated Water Resources Management Process 200
5.5.2.1 Social Conflicts of Water Use 200
5.5.2.2 Economic Conflicts 200
5.5.2.3 Legal Conflict 201
5.5.2.4 Water Conflicts in Perspective 201
5.5.3 Scales of Conflicts in Water Management 201
5.5.3.1 Global Scale of Water Conflicts 202
5.5.3.2 Regional Scale of Water Conflicts 203
5.5.3.3 Upstream and Downstream Relationship 205
5.5.4 Analysis of Causes of Conflicts in Water Management 205
5.6 Impact of Climate Change on Water Resource 206
5.6.1 Issues on Water Resources in Connection to Climate Change 206
5.6.1.1 Impact on Water Supply 206
5.6.1.2 Impact on Agricultural Water Demand 206
5.6.1.3 Impact on Municipal, Industrial Use 207
5.6.2 Adaptation Alternatives to the Climate Change 207
5.6.2.1 New Technology 208
5.6.2.2 Strengthen Flood Mitigation Measures 208
5.6.2.3 Enhance Drought Protection Strategies 208
5.6.2.4 Conservation Measure 208
5.6.2.5 Educate the People 209
5.7 Challenges in Water Resources Management 209
5.7.1 Risk and Uncertainties 209
5.7.2 International/Intra-national (Upstream--Downstream) Issues 209
5.7.3 Quality Degradation Due to Continuous Pumping of Groundwater 209
5.7.4 Lowering of WT and Increase in Cost of Pumping 210
Relevant Journals 210
Questions 211
References 211
6 Land and Watershed Management 213
6.1 Concepts and Scale Consideration 214
6.2 Background and Issues Related to Watershed Management 215
6.2.1 Water Scarcity 216
6.2.2 Floods, Landslides, and Torrents 216
6.2.3 Water Pollution 216
6.2.4 Population Pressure and Land Shrinkage 216
6.3 Fundamental Aspects of Watershed Management 217
6.3.1 Elements of Watershed 217
6.3.2 How the Watershed Functions 218
6.3.3 Factors Affecting Watershed Functions 218
6.3.4 Importance of Watershed Management 218
6.3.5 Addressing/Naming a Watershed 218
6.4 Land Grading in Watershed 219
6.4.1 Concept, Purpose, and Applicability 219
6.4.1.1 Concept 219
6.4.1.2 Purpose 219
6.4.1.3 Essential Conditions and Applicability 220
6.4.2 Precision Grading 220
6.4.3 Factors Affecting Land Grading and Development 221
6.4.3.1 Topography 221
6.4.3.2 Soil, Hydrologic, and Geologic Conditions 221
6.4.3.3 Climate and Microclimate 221
6.4.3.4 Indigenous Vegetation and Wildlife Habitats 222
6.4.3.5 Existing Regulatory Context 222
6.4.3.6 Sustainability Issues 222
6.4.3.7 Proposed Plan of Use 222
6.4.3.8 Field Size 222
6.4.3.9 Cost and Benefit Factors 222
6.4.4 Activities and Design Considerations in Land Grading 223
6.4.4.1 Furrow Grades 224
6.4.4.2 Cross Slope 224
6.4.4.3 Maximum Length of Runs for Irrigation 224
6.4.4.4 Other Considerations 225
6.4.5 Methods of Land Grading and Estimating Earthwork Volume 225
6.4.5.1 Planning and Early Surveying 225
6.4.5.2 Cutting and Filling 227
6.4.5.3 Construction Guidelines 227
6.4.5.4 Maintenance Considerations 228
6.4.5.5 Earth Work Volume Estimation 228
6.5 Runoff and Sediment Yield from Watershed 232
6.5.1 Runoff and Erosion Processes 232
6.5.2 Factors Affecting Runoff 233
6.5.2.1 Soil Type/Infiltration Rate 233
6.5.2.2 Rainfall 233
6.5.2.3 Vegetation 233
6.5.2.4 Topography 233
6.5.2.5 Surface Depressions, Ponds, and Other Natural Water Storage 234
6.5.2.6 Mulches and Crop Residues 234
6.5.2.7 Land Use 234
6.5.2.8 Soil Cover Management 234
6.5.2.9 Other Management Practices 234
6.5.3 Runoff Volume Estimation 234
6.5.3.1 The Rational Method 235
6.5.3.2 SCS Method 236
6.5.3.3 Sample Workout Problems on Runoff Estimation 238
Example 6.1 238
Solution 238
Example 6.2 238
Solution 238
Example 6.3 239
Solution 239
6.5.4 Factors Affecting Soil Erosion 239
6.5.4.1 Climate 239
6.5.4.2 Soils 239
6.5.4.3 Topography 240
6.5.4.4 Land Use 240
6.5.4.5 Vegetative Cover 240
6.5.4.6 Soil Cover Management/Cultural Practices 240
6.5.4.7 Other Management Practices 240
6.5.5 Sediment Yield and Its Estimation 241
6.5.5.1 Concept 241
6.5.5.2 Mechanism 241
6.5.5.3 Estimation 241
6.5.6 Sample Workout Problems on Sediment Yield Estimation 243
Example 6.4 243
Solution 243
Example 6.5 244
Solution 244
Example 6.6 244
Solution 245
6.5.7 Erosion and Sedimentation Control 245
6.5.8 Modeling Runoff and Sediment Yield 246
6.5.8.1 SWAT 247
6.5.8.2 KINEROS 247
6.5.8.3 AGWA 247
6.5.8.4 RUSLE2 247
6.6 Watershed Management 247
6.6.1 Problem Identification 247
6.6.2 Components of Watershed Management 248
6.6.3 Watershed Planning and Management 249
6.6.4 Tools for Watershed Protection 250
6.6.5 Land Use Planning 250
6.6.6 Structural Management 250
6.6.7 Pond Management 251
6.6.8 Regulatory Authority 251
6.6.9 Community-Based Approach to Watershed Management 251
6.6.9.1 Characteristics of Community-Based Watershed Management 251
6.6.9.2 Challenges Associated with Community-Based Watershed Management 253
6.6.9.3 Keys to Success of Community-Based Watershed Management 253
6.6.10 Land Use Planning and Practices 254
6.6.11 Strategies for Sustainable Watershed Management 255
6.7 Watershed Restoration and Wetland Management 256
6.7.1 Watershed Restoration 256
6.7.2 Drinking Water Systems Using Surface Water 256
6.7.3 Wetland Management in a Watershed 257
6.8 Addressing the Climate Change in Watershed Management 258
6.8.1 Groundwater Focus 258
Relevant Journals 258
Relevant FAO Papers/Reports 258
Questions 259
References 259
7 Pollution of Water Resources from Agricultural Fields and Its Control 261
7.1 Pollution Sources 262
7.1.1 Point Sources 262
7.1.2 Nonpoint Sources 262
7.2 Types of Pollutants/Solutes 263
7.2.1 Reactive Solute 263
7.2.2 Nonreactive Solute 263
7.3 Extent of Agricultural Pollution 263
7.3.1 Major Pollutant Ions 263
7.3.2 Some Relevant Terminologies 264
7.3.3 Factors Affecting Solute Contamination 264
7.3.4 Mode of Pollution by Nitrate and Pesticides 267
7.3.5 Hazard of Nitrate (NO 3 --N) Pollution 268
7.3.6 Impact of Agricultural Pollutants on Surface Water Body and Ecosystem 268
7.3.6.1 Impact of Eutrophication 268
7.3.6.2 Impact of Pesticides and Other Chemicals 269
7.4 Solute Transport Processes in Soil 270
7.4.1 Transport of Solute Through Soil 270
7.4.2 Basic Solute Transport Processes 271
7.4.2.1 Convective Solute Transport 271
7.4.2.2 Diffusive Solute Transport 272
7.4.2.3 Dispersive Solute Transport 273
7.4.3 Convection-Dispersion Equation 274
7.4.3.1 Assumptions in CDE 274
7.4.3.2 Drawbacks of CDE 274
7.4.4 Governing Equation for Solute Transport Through Homogeneous Media 274
7.4.4.1 Two-Dimensional Equation 274
7.4.4.2 One-Dimensional Transport 275
7.4.5 One-Dimensional Solute Transport with Nitrification Chain 276
7.4.6 Water Flow and Solute Transport in Heterogeneous Media 277
7.4.6.1 Dual Porosity Model for Solute Transport 277
7.5 Measurement of Solute Transport Parameters 278
7.5.1 Different Parameters 278
7.5.2 Breakthrough Curve and Breakthrough Experiment 279
7.5.2.1 Breakthrough Curve 279
7.5.2.2 Breakthrough Experiment 279
7.5.2.3 Analysis of Breakthrough Curve 280
7.6 Estimation of Solute Load (Pollution) from Agricultural Field 280
7.6.1 Sampling from Controlled Lysimeter Box 281
7.6.2 Sampling from Crop Field 281
7.6.3 Determination of Solute Concentration 282
7.6.3.1 Solute Transport Study by Tracer 283
7.6.3.2 Sample Examples on Solute Transport Problem 283
Example 7.1 283
Solution 283
Example 7.2 284
Solution 284
7.7 Control of Solute Leaching from Agricultural and Other Sources 285
7.7.1 Irrigation Management 285
7.7.2 Nitrogen Management 285
7.7.3 Cultural Management/Other Forms of Management 286
7.8 Models in Estimating Solute Transport from Agricultural and Other Sources 286
Relevant Journals 287
Questions 287
References 289
8 Management of Salt-Affected Soils 290
8.1 Extent of Salinity and Sodicity Problem 291
8.2 Development of Soil Salinity and Sodicity 292
8.2.1 Causes of Salinity Development 292
8.2.1.1 Salts in Soil 292
8.2.1.2 Salinity from Irrigation Water 292
8.2.1.3 Shallow Saline Groundwater 293
8.2.1.4 Landscape Feature 294
8.2.1.5 Climatic Condition 294
8.2.1.6 Man-Made Activity 294
8.2.1.7 Salinity from Urban Area 295
8.2.1.8 Seepage Salting/Salty Groundwater Discharge 295
8.2.2 Factors Affecting Salinity 296
8.2.2.1 Soil Moisture 296
8.2.2.2 Depth to Water Table 296
8.2.2.3 Method of Irrigation 296
8.2.2.4 Soil Factor 296
8.2.2.5 Climate 297
8.2.3 Mechanism of Salinity Hazard 297
8.2.4 Salt Balance at Farm Level 297
8.3 Diagnosis and Characteristics of Saline and Sodic Soils 298
8.3.1 Classification and Characteristics of Salt-Affected Soils 298
8.3.1.1 Saline Soil 299
8.3.1.2 Sodic Soil 300
8.3.1.3 Saline-Sodic Soil 301
8.3.2 Some Relevant Terminologies and Conversion Factors 301
8.3.2.1 Electrical Conductivity (EC) 302
8.3.2.2 Total Soluble Salts (TSS) or Total Dissolved Salts (TDS) 302
8.3.2.3 Exchangeable Sodium Percentage (ESP) 302
8.3.2.4 Sodium Adsorption Ratio (SAR) 303
8.3.2.5 Salinity 303
8.3.2.6 Salinization 303
8.3.2.7 Salinity and Osmotic Potential 303
8.3.2.8 Unit of EC 304
8.3.2.9 Unit Conversion 304
8.3.3 Diagnosis of Salinity and Sodicity 304
8.3.3.1 Diagnosis by Field Observation 305
8.3.3.2 Diagnosis by Laboratory Determination 305
8.3.3.3 Determination of Intensity of Salinity and Sodicity Hazard 308
8.3.4 Salinity Mapping and Classification 309
8.3.4.1 Salinity Mapping 309
8.3.4.2 Salinity Classification 310
8.4 Impact of Salinity and Sodicity 312
8.4.1 Impact of Salinity on Soil and Crop Production 312
8.4.2 Impact of Sodicity on Soil and Plant Growth 313
8.5 Crop Tolerance to Soil Salinity and Effect of Salinity on Yield 314
8.5.1 Factors Influencing Tolerance to Crop 314
8.5.1.1 Varietal Differences in Salt Tolerance 315
8.5.1.2 Growth Stage 315
8.5.1.3 Environmental Factors 316
8.5.1.4 Rootstocks and Salinity Tolerance 316
8.5.1.5 Soil Moisture 316
8.5.1.6 Soil Type 316
8.5.2 Relative Salt Tolerance of Crops 316
8.5.3 Use of Saline Water for Crop Production 317
8.5.4 Yield Reduction Due to Salinity 318
8.5.5 Sample Examples 319
Example 8.1 319
Solution 319
Example 8.2 320
Solution 320
8.6 Management/Amelioration of Saline Soil 320
8.6.1 Principles and Approaches of Salinity Management 320
8.6.2 Description of Salinity Management Options 321
8.6.2.1 Removing Surface Salts/Scraping 321
8.6.2.2 Control of Saline Water 321
8.6.2.3 Engineering Practices 322
8.6.2.4 Chemical Practices (Reclamation/Treatment of Saline Soil) 327
8.6.2.5 Irrigation and Water Management Practices 328
8.6.2.6 Biological Reduction of Salts 330
8.6.2.7 Other Management Options 330
8.6.2.8 Developing/Cultivating Salt Tolerant Crops 332
8.6.2.9 Increasing Water Use of Annual Crops and Pastures 333
8.6.2.10 Policy Formulation 333
8.6.2.11 Overall Discussion 333
8.6.2.12 Sample Examples 333
Example 8.3 333
Solution 333
Example 8.4 334
Solution 334
Example 8.5 334
Solution 335
Example 8.6 335
Solution 335
8.7 Management of Sodic and Saline-Sodic Soils 335
8.7.1 Management of Sodic Soil 336
8.7.1.1 Cation Exchange Reaction 336
8.7.1.2 Sample Examples 338
8.7.1.2 Example 8.7 338
8.7.1.2 Solution: 338
8.7.2 Management of Saline-Sodic Soil 338
8.8 Models/Tools in Salinity Management 339
2CSalt Model 339
BC2C Model 339
TARGET Model 339
SALT 339
WATSUIT 340
UNSATCHEM 340
SWMS-3D 340
SIWATRE 340
CropSyst -- Modified Version 340
LEACHC (Version of LEACHM) 341
SIWM Model 341
SIMPACT Model 341
SWAM 341
SGMP Computer Model 341
SALTMOD Computer Model 341
ENVIRO-GRO 342
SWASALT/SWAP 342
8.9 Challenges and Needs 342
Relevant Journals 342
Relevant FAO Papers/Reports 342
FAO Soils Bulletins 343
Questions 343
References 344
9 Drainage of Agricultural Lands 345
9.1 Concepts and Benefits of Drainage 347
9.1.1 Concepts 347
9.1.2 Goal and Purpose of Drainage 347
9.1.3 Effects of Poor Drainage on Soils and Plants 347
9.1.4 Benefits from Drainage 348
9.1.4.1 Major Benefits 348
9.1.4.2 Additional Benefits 348
9.1.5 Types of Drainage 348
9.1.5.1 Surface Drainage 348
9.1.5.2 Subsurface Drainage 349
9.1.6 Merits and Demerits of Deep Open and Buried Pipe Drains 350
9.1.7 Difference Between Irrigation Channel and Drainage Channel 352
9.2 Physics of Land Drainage 352
9.2.1 Soil Pore Space and Soil-Water Retention Behavior 352
9.2.2 Some Relevant Terminologies 353
9.2.2.1 Void Ratio ( e ) 353
9.2.2.2 Porosity 354
9.2.2.3 Relation Between Porosity and Void Ratio 354
9.2.2.4 Moisture Concentration 354
9.2.2.5 Pore Water 354
9.2.2.6 Drainable Pore Space or Drainable Porosity (Pd) 354
9.2.2.7 Drainable Water 355
9.2.2.8 Drainable Pore Volume Under Negative Pressure (or Suction) 356
9.2.3 Water Balance in a Drained Soil 356
9.2.4 Sample Workout Problem 358
Examples 9.1 358
Solution 358
9.3 Theory of Water Movement Through Soil and Toward Drain 358
9.3.1 Velocity of Flow in Porous Media 359
9.3.2 Some Related Terminologies 359
9.3.2.1 Drainage Intensity/Drainage Coefficient/Drainage Requirement 359
9.3.2.2 Drainage Density 359
9.3.2.3 Head 359
9.3.2.4 Water Table 359
9.3.2.5 Equipotential Line 360
9.3.2.6 Homogeneous and Isotropic Media 360
9.3.3 Resultant or Equivalent Hydraulic Conductivity of Layered Soil 360
9.3.3.1 Resultant Horizontal Hydraulic Conductivity 361
9.3.3.2 Resultant Vertical Hydraulic Conductivity 362
9.3.3.3 Resultant Conductivity of Horizontal and Vertical Direction 363
9.3.4 Laplace's Equation for Groundwater Flow 363
9.3.5 Functional Form of Water-Table Position During Flow into Drain 364
9.3.6 Theory of Groundwater Flow Toward Drain 364
9.3.6.1 Steady State Problems 364
9.3.6.2 Non-steady State Drainage Situation 365
9.3.7 Sample Workout Problems 365
Example 9.2 365
Solution 366
Example 9.3 366
Solution 366
9.4 Design of Surface Drainage System 367
9.4.1 Estimation of Design Surface Runoff 367
9.4.2 Design Considerations and Layout of Surface Drainage System 367
9.4.3 Hydraulic Design of Surface Drain 367
9.4.4 Sample Work Out Problem 368
Example 9.4 368
Solution 368
9.5 Equations/Models for Subsurface Drainage Design 369
9.5.1 Steady-State Formula for Parallel Drain Spacing 369
9.5.1.1 Hooghoudt's Equation 369
9.5.1.2 Donnan's Formula 372
9.5.2 Formula for Irregular Drain System 373
9.5.3 Determination of Drain Pipe Size 374
9.6 Design of Subsurface Drainage System 374
9.6.1 Factors Affecting Spacing and Depth of Subsurface Drain 374
9.6.1.1 Soil Salinity 374
9.6.1.2 Impact of Soil Texture on Drain Depth 374
9.6.2 Data Requirement for Subsurface Drainage Design 375
9.6.3 Layout of Subsurface Drainage 375
9.6.4 Principles, Steps, and Considerations in Subsurface Drainage Design 376
9.6.4.1 Principles 376
9.6.4.2 Steps 376
9.6.4.3 Estimation of Drainage Requirement or Drainage Coefficient 377
9.6.4.4 Criteria and Considerations 378
9.6.5 Controlled Drainage System and Interceptor Drain 379
9.6.5.1 Controlled Drainage 379
9.6.5.2 Interceptor Drain 380
9.6.6 Sample Workout Problems 380
Example 9.5 380
Solution 381
Example 9.6 381
Solution 381
Example 9.7 382
Solution 382
9.7 Envelope Materials 383
9.7.1 Need of Using Envelop Material Around Subsurface Drain 383
9.7.2 Need of Proper Designing of Envelop Material 383
9.7.3 Materials for Envelope 383
9.7.4 Design of Drain Envelope 384
9.7.4.1 Steps 384
9.7.4.2 Criteria for Selecting Envelope Material 384
9.7.4.3 Envelope Thickness 385
9.7.5 Use of Particle Size Distribution Curve in Designing Envelop Material 385
9.7.6 Drain Excavation and Envelope Placement 386
9.8 Models in Drainage Design and Management 386
9.8.1 DRAINMOD 386
9.8.2 CSUID Model 387
9.8.3 EnDrain 387
9.9 Drainage Discharge Management: Disposal and Treatment 387
9.9.1 Disposal Options 387
9.9.2 Treatment of Drainage Water 388
9.9.2.1 Physical/Chemical Treatment 388
9.10 Economic Considerations in Drainage Selection and Installation 389
9.11 Performance Evaluation of Subsurface Drainage 389
9.11.1 Importance of Evaluation 389
9.11.2 Evaluation System 390
9.12 Challenges and Needs in Drainage Design and Management 391
Relevant Journals 391
FAO/World Bank Papers 392
Questions 392
References 394
10 Models in Irrigation and Water Management 397
10.1 Background/Need of a Model 398
10.2 Basics of Model: General Concepts, Types, Formulation and Evaluation System 398
10.2.1 General Concepts 398
10.2.2 Different Types of Model 399
10.2.2.1 Physically Based or Process-Based Model 399
10.2.2.2 Empirical Models (or Black Box Models) 399
10.2.2.3 Conceptual Model 400
10.2.2.4 Mathematical and Statistical Models 400
10.2.2.5 Static and Dynamic Model 402
10.2.2.6 Mechanistic and Probabilistic Model 402
10.2.2.7 Deterministic and Stochastic Model 402
10.2.2.8 Time Series Model 403
10.2.2.9 Logical Model 403
10.2.3 Some related terminologies 404
10.2.3.1 Computer Model 404
10.2.3.2 Simulation 404
10.2.3.3 Different Parameters and Variables in Modeling 404
10.2.3.4 Sensitivity Analysis 405
10.2.3.5 Model Validation 406
10.2.3.6 Confidence and Uncertainty 406
10.2.3.7 Implicit Vs Explicit Scheme/Method, and Stability Issue 406
10.2.3.8 Finite Element and Finite Difference Scheme/Method 406
10.2.4 Basic Considerations in Model Development and Formulation of Model Structure 407
10.2.4.1 Basic Considerations 407
10.2.4.2 Formulation of Model 407
10.2.5 Model Calibration, Validation and Evaluation 408
10.2.5.1 Model Calibration 409
10.2.5.2 Model Verification/Validation 409
10.2.6 Statistical Indicators for Model Performance Evaluation 409
10.3 Overview of Some of the Commonly Used Models 411
10.3.1 Model for Reference Evapotranspiration (ET 0 Models) 411
10.3.1.1 CROPWAT Model 411
10.3.1.2 CropET 0 Model 414
10.3.2 Model for Upward Flux Estimation 415
10.3.2.1 Model UPFLOW 415
10.3.3 Model for Flow Estimation in Cracking Clay Soil 415
10.3.3.1 FLOCR 416
10.3.3.2 MACRO 420
10.3.4 Model for Irrigation Planning and Decision Support System 420
10.3.4.1 CROPWAT 420
10.3.4.2 CropSyst 421
10.3.5 Decision Support Model 423
10.3.5.1 DSSAT 423
10.3.5.2 APSIM 424
10.4 Crop Production Function/Yield Model 424
10.4.1 Definition of Production Function 424
10.4.2 Importance of Production Function 424
10.4.3 Basic Considerations in Crop Production Function 425
10.4.4 Pattern of Crop Production Function 425
10.4.5 Development of Crop Production Function 426
10.4.6 Some Existing Yield Functions/Models 426
10.4.7 Limitations/Drawbacks of Crop Production Function 429
10.5 Regression-Based Empirical Models for Predicting Crop Yield from Weather Variables 429
10.5.1 Need of Weather-Based Prediction Model 429
10.5.2 Existing Models/Past Efforts 430
10.5.3 Methods of Formulation of Weather-Based Prediction Model 431
10.5.3.1 The Typical Form of a Model 432
10.5.3.2 Basic Assumptions in Regression-Based Prediction Model 432
10.5.4 Discussion 433
10.5.5 Sample Example of Formulating Weather-Based Yield-Prediction Model 433
10.5.5.1 Formulation 434
Relevant Journals 437
Questions 437
References 438
11 GIS in Irrigation and Water Management 441
11.1 Introduction 442
11.2 Definition of GIS 442
11.3 Benefits of GIS Over Other Information Systems 442
11.4 Major Tasks in GIS 443
11.5 Applications of GIS 443
11.6 Techniques Used in GIS 445
11.7 Implementation of GIS 445
11.8 Data and Databases for GIS 446
11.9 Sources of Spatial Data 446
11.10 Data Input 447
11.11 GIS-Based Modeling or Spatial Modeling 447
11.12 Remote Sensing Techniques 448
Relevant Journals 449
Questions 449
References 449
12 Water-Lifting Devices Pumps 451
12.1 Classification of Water-Lifting Devices 453
12.1.1 Human-Powered Devices 453
12.1.1.1 Swing Basket 453
12.1.1.2 Don 453
12.1.1.3 Archimedean Screw 454
12.1.1.4 Paddle Wheel 454
12.1.2 Animal-Powered Devices 454
12.1.3 Kinetic Energy Powered Device 454
12.1.3.1 Hydraulic Ram 454
12.1.4 Mechanically Powered Water-Lifting Devices 455
12.2 Definition, Purpose, and Classification of Pumps 455
12.2.1 Definition of Pump 455
12.2.2 Pumping Purpose 455
12.2.3 Principles in Water Pumping 456
12.2.4 Classification of Pumps 456
12.2.4.1 Classification Based on Mode of Intake of Fluid to Pumps 456
12.2.4.2 Classification Based on the Position of Prime Mover 457
12.2.4.3 Classification Based on the Type of Water Use (or Field of Use) 457
12.2.4.4 Classification Based on the Principle by Which Energy Is Added to the Fluid 458
12.2.4.5 Classification Based on the Means by Which the Energy Is Added 459
12.3 Factors Affecting the Practical Suction Lift of Suction-Mode Pump 460
12.4 Centrifugal Pumps 460
12.4.1 Features and Principles of Centrifugal Pumps 460
12.4.2 Some Relevant Terminologies to Centrifugal Pump 461
12.4.2.1 Suction Lift 461
12.4.2.2 Net Positive Suction Head Available 461
12.4.2.3 Net Positive Suction Head required (NPSHr) 462
12.4.2.4 Static and Dynamic Head 462
12.4.2.5 Total Head 463
12.4.3 Pump Efficiency 463
12.4.4 Specific Speed 464
12.4.5 Affinity Laws 464
12.4.6 Priming of Centrifugal Pumps 466
12.4.7 Cavitation 467
12.5 Description of Different Types of Centrifugal Pumps 467
12.5.1 Turbine Pump 467
12.5.1.1 Deep-Well Turbine Pumps 468
12.5.2 Submersible Pump 469
12.5.2.1 Suitability of Submersible Pump 470
12.5.2.2 Features 471
12.5.2.3 Applications 471
12.5.2.4 Requirements for Submersible Pump 471
12.5.2.5 Wide Ranges of Submersible Pumps 471
12.5.2.6 Open Well Submersible Pump 471
12.5.2.7 Open Well Submersible Pumps 472
12.5.3 Mono-Block Pump 472
12.5.3.1 Features 472
12.5.3.2 Uses 473
12.5.4 Radial-Flow Pump 473
12.5.5 Volute Pump 474
12.5.6 Axial-Flow Pump 474
12.5.7 Mixed-Flow Pump 474
12.5.8 Advantage and Disadvantage of Different Centrifugal Pumps 475
12.5.9 Some Common Problems of Centrifugal Pumps, Their Probable Causes, and Remedial Measures 475
12.6 Other Types of Pumps 476
12.6.1 Air-Lift Pump 476
12.6.2 Jet Pump 477
12.6.2.1 Features 478
12.6.2.2 Uses 479
12.6.3 Reciprocating Pump/Bucket Pump 479
12.6.3.1 Features 479
12.6.3.2 Uses 479
12.6.4 Displacement Pump 480
12.6.5 Hydraulic Ram Pump 480
12.6.6 Booster Pump 480
12.6.7 Variable Speed Pump 480
12.7 Cavitation in Pump 480
12.7.1 Cavitation in Radial Flow and Mixed Flow Pumps 481
12.7.2 Cavitation in Axial-Flow Pumps 481
12.8 Power Requirement in Pumping 481
12.9 Pump Installation, Operation, and Control 482
12.9.1 Pump Installation 483
12.9.1.1 Installation 483
12.9.1.2 Alignment 483
12.9.1.3 Installation of Submersible Pump 483
12.9.2 Pump Operation 484
12.9.2.1 Suction Line 484
12.9.2.2 Field Test 484
12.9.2.3 Operational Check 485
12.9.3 Pump Control 485
12.9.3.1 Automating the Control Circuit 485
12.10 Hydraulics in Pumping System 486
12.10.1 Pressure Vs Flow Rate 486
12.10.2 Pressure and Head 486
12.10.2.1 Dynamic Water Depth 486
12.10.3 Elevation Difference 487
12.11 Pumps Connected in Series and Parallel 487
12.12 Pump Performance and Pump Selection 487
12.12.1 Pump Performance 487
12.12.2 Factors Affecting Pump Performance 487
12.12.3 Selecting a Pump 488
12.12.4 Procedure for Selecting a Pump 488
12.12.4.1 Pump Selection from Pump Curves 489
12.12.4.2 Pump Selection Based on Pump Characteristics and Well Characteristics 490
12.13 Sample Workout Problems on Pump 491
Example 12.1 491
Solution 491
Example 12.2 491
Solution 491
Example 12.3 492
Solution 492
Example 12.4 492
Solution 492
Example 12.5 493
Solution 493
Example 12.6 493
Solution 494
Example 12.7 494
Solution 494
Example 12.8 494
Questions 494
13 Renewable Energy Resources for Irrigation 496
13.1 Concepts and Status of Renewable Energy Resources 497
13.1.1 General Overview 497
13.1.2 Concept and Definition of Renewable Energy 498
13.1.3 Present Status of Uses of Renewable Energy 499
13.2 Need of Renewable Energy 499
13.3 Mode of Use of Renewable Energy 500
13.4 Application of Solar Energy for Pumping Irrigation Water 500
13.4.1 General Overview 500
13.4.2 Assessment of Potential Solar Energy Resource 501
13.4.2.1 Theoretical Potential 501
13.4.2.2 Technical Potential 501
13.4.3 Solar or Photovoltaic Cells -- Theoretical Perspectives 502
13.4.4 Solar Photovoltaic Pump 502
13.4.4.1 Photovoltaic System Types 502
13.4.4.2 Photovoltaic System Design for Irrigation Water Pumping 503
13.4.4.3 Economics of Photovoltaic Irrigation Pumping 505
13.4.4.4 Sample Work Out Problems 505
Example 13.1 505
Solution 505
Example 13.2 505
Solution 506
Example 13.3 506
Solution 506
13.4.5 Uses of Solar System Other than Irrigation Pumping 506
13.4.6 Solar Photovoltaic Systems to Generate Electricity Around the Globe 507
13.5 Wind Energy 508
13.5.1 Wind as a Renewable and Environmentally Friendly Source of Energy 508
13.5.2 Historical Overview of Wind Energy 508
13.5.3 Causes of Wind Flow 509
13.5.4 Energy from Wind 510
13.5.5 Advantages of Wind Energy 510
13.5.6 Assessing Wind Energy Potential 511
13.5.7 Types of Wind Machines 512
13.5.7.1 Horizontal-Axis 512
13.5.7.2 Vertical-Axis 512
13.5.8 Suitable Site for Windmill 512
13.5.8.1 Characterization of the Resource 513
13.5.9 Application of Wind Energy 513
13.5.9.1 Mode of Use of Wind Power 513
13.5.9.2 Water Pumping Windmill 513
13.5.9.3 Wind in Production of Electricity 513
13.5.10 Working Principle of Wind Machines 514
13.5.11 Wind Power Plants or Wind Farms 515
13.5.11.1 Seasonal Variation of Wind Energy 515
13.5.12 Calculation of Wind Power 515
13.5.13 Intermittency Problem with Wind Energy 517
13.5.14 Wind and the Environment 518
13.5.15 Sample Work Out Problems 518
Example 13.4 518
Solution 518
Example 13.5 519
Solution 519
Example 13.6 519
Solution 519
13.6 Water Energy 519
13.6.1 Forms of Water Energy 520
13.6.2 Wave Energy 520
13.6.3 Watermill 521
13.6.3.1 Working Principle of Watermills 521
13.6.3.2 Types 522
13.6.4 Tide Mill 522
13.6.5 Exploring the Potentials of Water Power 522
13.7 Bio-energy 523
13.7.1 Liquid Biofuel 524
13.7.2 Biogas 525
13.8 Geothermal Energy 525
13.9 Modeling the Energy Requirement 526
13.10 Factors Affecting Potential Use of Renewable Energy in Irrigation 526
13.10.1 Groundwater Requirement and Its Availability 527
13.10.2 Affordability of the User 527
13.10.3 Willingness of the User to Invest in a Renewable Energy Based Pump 527
13.10.4 Availability of Alternate Energy for Irrigation and Its Cost 528
13.10.5 Alternate Use of Renewable Energy 528
13.11 Renewable Energy Commercialization: Problems and Prospects 528
13.11.1 Problems 529
13.11.1.1 Costs 529
13.11.1.2 Availability and Reliability 529
13.11.1.3 Aesthetics 529
13.11.1.4 Environmental and Social Considerations 529
13.11.1.5 Land Area Required 530
13.11.1.6 Incapability of Generating Large Amount of Energy 530
13.11.1.7 Longevity Issues 530
13.11.1.8 Sustainability 530
13.11.1.9 Transmission 531
13.11.2 Prospects/Future Potentials 531
13.11.3 Challenges and Needs 533
Relevant Journals 533
Questions 534
References 535
Subject Index 536