Estuaries: Dynamics, Mixing, Sedimentation and Morphology

Half-title......Page 3
Title......Page 5
Copyright......Page 6
Contents......Page 7
Symbols......Page 10
1.1.1 Processes......Page 13
1.1.2 Historical developments......Page 14
1.2.1 Evolving science and technology agendas......Page 15
1.2.2 Key questions......Page 16
1.3.1 Sequence......Page 17
1.3.2 Tidal dynamics......Page 18
1.3.4 Saline intrusion......Page 19
1.3.5 Sediment regimes......Page 20
1.3.6 Synchronous estuary: dynamics, saline intrusion and bathymetry......Page 21
1.3.7 Synchronous estuary: sediment trapping and sorting – stable morphology......Page 22
1.3.8 Strategies for sustainability......Page 24
Resolution......Page 25
1.4.2 Observations......Page 27
1.5 Summary of formulae and theoretical frameworks......Page 28
1A.1 Tide generation......Page 29
1A.2 Non-rotating Earth......Page 30
1A.5 Elliptic orbit......Page 31
1A.9 Monthly, fortnightly and quarter-diurnal constituents......Page 32
References......Page 33
2.1 Introduction......Page 35
2.2 Equations of motion......Page 36
2.3.1 Linearised solution......Page 38
2.3.2 Synchronous estuary solution......Page 39
Role of bed friction......Page 41
2.4 Tidal response – whole estuary......Page 43
2.4.1 Breadth and depth varying with powers of distance X (Prandle and Rahman, 1980)......Page 44
2.4.2 Depth and breadth varying exponentially (Hunt, 1964 Prandle, 1985)......Page 47
2.5.2 Two constituents......Page 50
2.5.3 Triangular cross section......Page 51
2.6 Higher harmonics and residuals......Page 52
2.6.2 Non-linear terms in the tidal equations......Page 53
Convective term......Page 54
2.6.3 Ebb–flood asymmetry......Page 55
2.7 Surge–tide interactions......Page 56
2.8 Summary of results and guidelines for application......Page 58
References......Page 60
3.1 Introduction......Page 62
3.1.1 Convective term......Page 63
3.1.4 Approach......Page 64
3.2.1 2D analytical solution......Page 65
Boundary conditions......Page 66
3.2.2 Comparisons with observations......Page 67
3.2.3 Eddy viscosity formulation, Strouhal number......Page 69
3.3.1 Tidal ellipse resolved into clockwise and anti-clockwise components......Page 71
3.3.2 3D analytical solution......Page 73
3.3.3 Sensitivity to friction factor and eddy viscosity......Page 74
3.3.4 Sensitivity to latitude......Page 75
3.3.5 Surface to bed changes in tidal ellipses......Page 76
3.4.1 Wind-driven currents......Page 79
3.4.2 Tidal current residuals......Page 81
3.5 Summary of results and guidelines for application......Page 83
3A.1 Tidal current ellipse......Page 85
3B.1 Turbulence model......Page 87
References......Page 88
4.1 Introduction......Page 90
4.1.1 Classification systems......Page 91
4.1.2 Mixing in estuaries......Page 92
4.1.3 Present approach......Page 95
4.2 Current structure for river flow, mixed and stratified saline intrusion......Page 96
4.2.1 Current structure for river flow Q......Page 97
4.2.2 Current structure for a well-mixed horizontal density gradient......Page 98
4.2.3 Current structure for a stratified two-layer density regime......Page 99
4.2.5 Time-averaged vertical salinity structure (mixed)......Page 101
4.3.1 Experimental derivation......Page 102
4.3.2 Derivations from velocity components......Page 103
Observed versus computed values......Page 104
4.3.5 Axial location of saline intrusion......Page 105
4.4.1 Rates of mixing......Page 108
4.4.3 Model formulation......Page 109
Currents......Page 110
Salinity......Page 111
4.4.5 Model applications for a range of estuarine conditions......Page 112
Tidal velocities......Page 113
Bed-to-surface residual current differencesδu and sea level gradient ∂ς/∂X......Page 114
Bed-to-surface density differences, δs......Page 115
4.4.6 Mixing processes......Page 116
4.5.2 Energy and time requirements......Page 117
4.5.4 Stratification number......Page 118
4.5.5 Vertical salinity difference......Page 119
4.6 Summary of results and guidelines for application......Page 120
4A.1 The annual temperature cycle......Page 123
4A.2 Components of heat exchange at the sea surface......Page 124
4A.3 Analytical solutions in vertically mixed water......Page 125
4A.5 The atmospheric model – solar energy input, reflection, absorption and radiation......Page 129
4A.6 Global expressions......Page 130
References......Page 132
5.1.1 Sediment dynamics......Page 135
5.1.2 Modelling......Page 136
5.1.3 Approach......Page 137
5.2 Erosion......Page 138
5.2.2 Spring–neap cycle......Page 139
5.2.3 Erosion in shallow cross sections......Page 140
5.3.1 Advective settlement versus turbulent suspension (Peclet number)......Page 141
5.3.2 Bottom boundary conditions......Page 142
5.4.1 Time series of sediment concentration profiles......Page 143
5.4.2 Exponential deposition, half-lives in suspension, t50......Page 144
5.4.3 Vertical profile of suspended sediments......Page 146
5.5 SPM time series for continuous tidal cycles......Page 147
5.6.1 Observational technologies......Page 149
5.6.2 Observed time series......Page 150
5.6.3 Modelled time series......Page 152
5.7 Summary of results and guidelines for application......Page 154
5.7.1 Sediment suspension......Page 155
5.7.3 Tidal spectra of SPM......Page 156
5A.2 Dispersion equation......Page 157
5A.5 Boundary condition at the bed z = 2, 4, 6, etc.......Page 159
References......Page 161
6.1 Introduction......Page 163
6.2.1 Synchronous estuary approach......Page 164
6.2.2 Analytical solution for 1D momentum and continuity equations (Prandle, 2003)......Page 165
Depth profile and estuarine length L......Page 167
6.2.4 Sensitivity to bed friction coefficient (f)......Page 168
6.2.5 Rate of funnelling in a synchronous estuary......Page 169
6.3.1 Stratification levels and flushing times......Page 170
6.3.2 Location of mixing zone, residual current associated with river flow......Page 172
6.4.1 Morphological zone determined by tidal dynamics and stratification......Page 173
6.4.2 Estuarine depths as a function of river flow......Page 175
Observed versus computed estuarine bathymetries......Page 176
6.5.1 Statistical analyses......Page 177
6.5.2 Theory versus observed morphologies......Page 179
6.5.3 Minimum depths and flows for estuarine functioning......Page 180
6.5.4 Spacing between estuaries......Page 181
What determines estuarine shape, length and depth?......Page 182
Range of estuarine morphologies......Page 183
Theoretical Frameworks......Page 184
References......Page 185
7.1.1 Earlier studies......Page 187
7.1.2 Approach......Page 189
7.2 Tidal dynamics, saline intrusion and river flow......Page 191
7.2.1 Analytical solution for 1D tidal propagation (Chapter 6 Prandle, 2003)......Page 192
7.2.2 Saline intrusion (Chapter 4)......Page 193
Erosion......Page 194
Vertical profile of suspended sediments......Page 195
Mean concentration......Page 196
7.4.2 Mass of sediments in suspension......Page 197
7.4.3 Net sediment fluxes......Page 198
7.5 Component contributions to net sediment flux......Page 199
7.5.1 Components of sediment flux: river flow, salinity and tidal current constituents......Page 200
7.5.2 Conditions for zero net flux of sediments......Page 202
7.5.3 Sensitivity to fall velocity, Ws......Page 203
7.5.4 Sensitivity to bed friction, f, and fall velocity, Ws......Page 204
7.6 Import or export of sediments?......Page 205
7.6.1 Sensitivity to half-life, t50, and phase difference, theta, between tidal elevation and current......Page 206
7.6.2 Sediment trapping and turbidity maxima......Page 207
7.7.1 Bathymetry......Page 208
7.7.2 Sediment regimes......Page 210
7.8 Summary of results and guidelines for application......Page 211
7.8.1 Component contributions and sensitivity analyses......Page 212
7.8.3 Neap to spring, coarse to fine, mouth to head variations in net import versus export......Page 213
References......Page 214
8.1 Introduction......Page 217
Suspended sediments and net deposition......Page 218
Bathymetry......Page 219
8.2.2 Modelling approach......Page 220
8.2.3 Lagrangian, random-walk particle module for non-cohesive sediment......Page 222
8.2.4 Simulations for fall velocities, WS = 0.005 and 0.0005 ms-1......Page 223
8.2.5 Sensitivity to sediment size......Page 225
8.2.6 Sensitivity to model parameters......Page 229
8.3 Impacts of GCC......Page 230
8.3.2 Bathymetric adjustments......Page 233
8.3.3 Depth, breadth and length changes for 2100 variations in msl and river flow......Page 234
8.4.1 Modelling......Page 235
8.4.2 Observations......Page 236
8.4.3 Monitoring......Page 237
8.5.2 Modelling case study......Page 238
8.5.3 Strategic planning......Page 239
8A.1 Operational oceanography......Page 240
Assimilation......Page 241
8A.3 Model generations......Page 242
References......Page 243
Index......Page 246