Open Channel Hydraulics (eBook)

Front Cover 1
Title Page 4
Copyright Page 5
Table of Contents 6
Preface 10
Acknowledgments 12
Chapter 1 Fundamentals of open-channel flow 14
1.1 Geometric elements of open channels 14
1.2 Velocity and Discharge 15
1.3 Hydrostatic pressure 15
1.4 Mass, momentum and energy transfer in open-channel flow 20
1.4.1 Mass Transfer 20
1.4.2 Momentum Transfer 20
1.4.3 Energy Transfer 21
1.5 Open-channel flow classification 23
1.6 Conservation laws 24
1.6.1 Conservation of Mass 24
1.6.2 Conservation of Momentum 25
1.6.3 Conservation of Energy 27
1.6.4 Steady Flow Equations 30
1.6.5 Steady Spatially-Varied Flow Equations 31
1.6.6 Comparison and Use of Momentum and Energy Equations 33
Chapter 2 Energy and momentum principles 37
2.1 Critical flow 37
2.1.1 Froude Number 37
2.1.2 Calculation of Critical Depth 38
2.2 Applications of energy principle for steady flow 41
2.2.1 Energy Equation 41
2.2.2 Specific Energy Diagram for Constant Discharge 44
2.2.3 Discharge Diagram for Constant Specific Energy 53
2.2.4 Specific Energy in Rectangular Channels 54
2.2.5 Choking of Flow 58
2.3 Applications of momentum principle for steady flow 60
2.3.1 Momentum Equation 60
2.3.2 Specific Momentum Diagram for Constant Discharge 62
2.3.3 Discharge Diagram for Constant Specific Momentum 66
2.3.4 Hydraulic Jump 67
2.3.5 Specific Momentum in Rectangular Channels 71
2.3.6 Hydraulic Jump in Rectangular Channels 74
2.3.7 Choking and Momentum Principle 76
Chapter 3 Normal flow 80
3.1 Flow resistance 80
3.1.1 Boundary layer and flow resistance 81
3.1.2 The Darcy-Weisbach equation 83
3.1.3 The Chezy equation 84
3.1.4 The Manning formula 85
3.2 Normal flow equation 87
3.3 Normal depth calculations in uniform channels 89
3.4 Normal depth calculations in grass-lined channels 93
3.5 Normal depth calculations in riprap channels 96
3.6 Normal flow in composite channels 99
3.7 Normal flow in compound channels 101
Chapter 4 Gradually-varied flow 110
4.1 Classification of channels for gradually-varied flow 111
4.2 Classification of gradually-varied flow profiles 112
4.3 Significance of Froude number in gradually-varied flow calculations 114
4.4 Qualitative determination of expected gradually-varied flow profiles 117
4.5 Gradually-varied flow computations 123
4.5.1 Direct step method 124
4.5.2 Standard step method 131
4.6 Applications of gradually-varied flow 134
4.6.1 Locating hydraulic jumps 134
4.6.2 Lake and channel problems 137
4.6.3 Two-lake problems 143
4.6.4 Effect of choking on water surface profile 147
4.7 Gradually-varied flow in channel systems 154
4.8 Gradually-varied flow in natural channels 157
Chapter 5 Design of open channels 170
5.1 General design considerations 170
5.2 Design of unlined channels 172
5.2.1 Maximum permissible velocity method 172
5.2.2 Tractive force method 176
5.2.3 Channel bends 185
5.3 Design of channels with flexible linings 187
5.3.1 Design of channels lined with vegetal cover 188
5.3.2 Design of riprap channels 192
5.3.3 Temporary flexible linings 199
5.4 Design of rigid boundary channels 201
5.4.1 Experience curve approach 202
5.4.2 Best hydraulic section approach 204
5.4.3 Minimum lining cost approach 205
5.5 Channel design for non-uniform flow 207
Chapter 6 Hydraulic structures 213
6.1 Flow measurement structures 213
6.1.1 Sharp-crested weirs 213
6.1.2 Broad-crested weirs 220
6.1.3 Flumes 222
6.2 Culverts 225
6.2.1 Inlet control flow 227
6.2.2 Outlet control flow 233
6.2.3 Sizing of culverts 238
6.3 Overflow spillways 238
6.3.1 Shape for uncontrolled ogee crest 239
6.3.2 Discharge over an uncontrolled ogee crest 240
6.3.3 Discharge over gate-controlled ogee crests 243
6.4 Stilling basins 245
6.4.1 Position of hydraulic jump 245
6.4.2 Hydraulic jump characteristics 251
6.4.3 Standard stilling basin designs 252
6.5 Channel transitions 257
6.5.1 Channel transitions for subcritical flow 257
6.5.2 Channel transitions for supercritical flow 265
Chapter 7 Bridge hydraulics 279
7.1 Modeling bridge sections 279
7.1.1 Cross-section locations 279
7.1.2 Low-flow types at bridge sites 282
7.1.3 Low-flow calculations at bridge sites 282
7.1.4 High-flow calculations at bridge sites 297
7.2 Evaluating scour at bridges 307
7.2.1 Contraction scour 309
7.2.2 Local scour at piers 316
7.2.3 Local scour at abutments 321
Chapter 8 Introduction to unsteady open-channel flow 328
8.1 Governing equations 328
8.2 Numerical solution methods 331
8.2.1 Explicit finite difference schemes 332
8.2.2 Implicit finite difference schemes 334
8.2.3 Special considerations 351
8.2.4 Channel systems 354
8.3 Approximate unsteady-flow models 355
8.3.1 Diffusion-wave model for unsteady flow 355
8.3.2 Finite difference equations 356
8.3.3 Solution of finite difference equations 357
8.4 Simple channel-routing methods 360
8.4.1 The Muskingum method 360
8.4.2 The Muskingum-Cunge method 364
Index 374