An Introduction to Coastal Engineering
Description
Understand and respond to a changing coastline with this comprehensive reference
Coastal engineering concerns society's interactions with coastlines and relates, for example, to coastal flooding, beach erosion, seawalls and breakwaters, and the design of marinas. As climate change drives sea level rise, coastal engineering is critical in responding to increased coastal flooding and receding shorelines. The need to develop coastal infrastructure while minimizing environmental impacts makes this a vital field.
An Introduction to Coastal Engineering offers a comprehensive overview of this subject, designed to bridge existing gaps in the general civil engineering literature. Covering all major aspects of coastal engineering, including ocean wave behaviour, structures, sediments, mixing processes, and modelling, the book emphasizes practical solutions and applications for students and practicing engineers alike. Thorough and rigorous, yet highly readable, the book is a must-own tool for developing solutions towards a sustainable coastal future.
An Introduction to Coastal Engineering readers will also find:
- Pertinent descriptions of wave theories, wave transformations, and random waves
- Detailed discussion of practical solutions, recent advancements in the field, and up-to-date data sources
- Worked-through examples and end-of-chapter problems with some written assignments
- A spreadsheet appendix containing a set of reference solutions
An Introduction to Coastal Engineering is ideal for students in upper-level undergraduate and graduate courses in coastal engineering, practicing coastal engineers, and other engineers engaged in coastal flood protection, waterfront development projects, and the minimization of environmental impacts along shorelines.
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Michael Isaacson, Ph.D., P.Eng., is Professor Emeritus of Civil Engineering at the University of British Columbia, Canada. He has decades of experience teaching coastal engineering and undertaking coastal engineering projects, his publication record includes over 200 papers on coastal engineering topics, and he has served on numerous professional committees and boards.
Content
About the Author xvii
Preface xix
About the Companion Website xxi
1 Introduction 1
1.1 Scope of Coastal Engineering 1
1.2 Outline of Book 1
1.3 Example Projects 3
1.3.1 Coastal Flooding 3
1.3.2 Coastal Structure Design 4
1.3.3 Sediment Transport 4
1.3.4 Marina Design 6
1.4 Evolution of Coastal Engineering and Future Trends 6
2 Regular Waves 9
2.1 Introduction 9
2.2 Boundary Value Problem 10
2.2.1 Assumptions 11
2.2.2 Equations of Motion 11
2.2.3 Boundary Conditions 11
2.2.4 Governing Equations 12
2.3 Linear Wave Theory 13
2.3.1 Governing Equations 13
2.3.2 Solution for Flow Field 14
2.3.3 Depth Parameter 15
2.3.4 Description of Results 16
2.3.5 Linear Dispersion Relation 17
2.4 Wave Energy and Momentum 20
2.5 Waves with a Current 21
2.5.1 Fixed and Moving Reference Frames 22
2.5.2 Solution for Flow Field 22
2.5.3 Dispersion Relation 23
2.6 Extensions to Linear Wave Theory 24
2.6.1 Waves Propagating at An Angle to the X Axis 24
2.6.2 Reference Frame Moving with the Waves 25
2.6.3 Stream Function Representation 26
2.6.4 Complex Representation 26
2.7 Nonlinear Wave Theories 27
2.7.1 Stokes Wave Theories 27
2.7.2 Cnoidal Wave Theories 28
2.7.3 Solitary Wave Theories 28
2.7.4 Numerical Wave Theories 29
Problems 30
3 Wave Transformations 31
3.1 Wave Shoaling 31
3.1.1 Assumptions 32
3.1.2 Shoaling Relations 32
3.2 Wave Refraction 33
3.2.1 Refraction Relations 33
3.2.2 Numerical Modeling of Shoaling and Refraction 36
3.3 Wave Diffraction 39
3.3.1 Boundary Value Problem 39
3.3.2 Example Solutions 41
3.3.3 Straight Semi-Infinite Breakwater - Closed-Form Solution 41
3.3.4 Straight Semi-Infinite Breakwater - Diffraction Diagrams 43
3.3.5 Guidelines and Approximations on the Use of Diffraction Diagrams 43
3.4 Standing Waves 46
3.4.1 Standing Waves at a Wall 46
3.4.2 Standing Waves in a Basin 47
3.5 Wave Reflection 49
3.5.1 Normal Reflection 49
3.5.2 Oblique Reflection 50
3.6 Wave Transmission 51
3.7 Wave Attenuation 52
3.7.1 Forms of Energy Dissipation 52
3.7.2 Friction Factor 53
3.7.3 Attenuation Rate 54
3.8 Waves of Maximum Height 54
3.9 Breaking Waves 55
3.9.1 Forms of Wave Breaking 56
3.9.2 Breaking Wave Height and Depth 56
3.10 Wave Runup 58
3.11 Numerical Models 60
3.11.1 Overview 60
3.11.2 Models Based on the Mild-Slope Equation 60
3.11.3 Models Based on Boussinesq-Type Equations 62
Problems 63
4 Random Waves 65
4.1 Introduction 65
4.2 Probability Distribution of Wave Heights 66
4.3 Wave Spectra 69
4.3.1 One-Dimensional Spectra 69
4.3.2 Transformation of Wave Spectra 70
4.3.3 Directional Wave Spectra 73
4.3.4 Time-Frequency Domain Conversions 75
4.4 Long-Term Variability of Storms 77
4.5 Extreme Value Analysis 77
4.5.1 Overview 77
4.5.2 Exceedance Probabilities 78
4.5.3 Distribution Selection and Fit 78
4.5.4 Return Period and Annual Exceedance Probability 80
4.5.5 Encounter Probability 80
4.6 EVA Alternatives and Extensions 82
4.6.1 Annual Maxima 82
4.6.2 Lower Return Periods 83
4.6.3 Seasonal Conditions 83
4.6.4 Confidence Bands 83
4.7 Annual Wave Conditions 83
4.7.1 Wave Scatter Diagram 83
4.7.2 Long-Term Distribution of Individual Wave Heights 84
4.7.3 Application to Hours Per Year 85
4.7.4 Application to Fatigue Calculations 85
Problems 86
5 Winds 89
5.1 Introduction 89
5.2 Wind Data 89
5.3 Annual Wind Conditions 90
5.4 Design Wind Speeds 91
5.5 Wind Speed Correction Factors 93
5.5.1 Averaging Period 93
5.5.2 Elevation 93
5.5.3 Overland to Overwater Conversion 94
5.5.4 Atmospheric Stability 94
5.6 Hurricanes 95
5.6.1 Tropical Cyclone Categories 95
5.6.2 Saffir-Simpson Scale 96
5.6.3 Wind and Pressure Fields 96
5.6.4 Hurricane Tracks 97
Problems 99
6 Wave Predictions 101
6.1 Introduction 101
6.1.1 General Approaches 101
6.1.2 Wave Generation by Wind 102
6.2 Wave Hindcasting - Simplified Approach 103
6.3 Wave Hindcasting and Forecasting - Numerical Models 107
6.3.1 Spectral Wave Models 107
6.3.2 Extension to Intermediate and Shallow Depths 108
6.3.3 Regional and Global Models 108
6.3.4 Operational Forecasting 110
6.4 Ship Waves 110
6.5 Laboratory-Generated Waves 112
6.5.1 Overview 112
6.5.2 Wavemaker Theory 112
Problems 114
7 Long Waves, Water Levels, and Currents 115
7.1 Long Wave Theories 115
7.1.1 Linearized Long Wave Theory 115
7.1.2 Nonlinear Long Wave Theories 116
7.2 Tides 117
7.2.1 Introduction and Historical Development 117
7.2.2 Glossary 118
7.2.3 Prediction of Tide Levels 119
7.2.4 Vertical Datums 120
7.2.5 Tidal and Bathymetric Data 120
7.2.6 Tidal Bores 121
7.3 Tsunamis 122
7.3.1 Introduction and Examples 122
7.3.2 Tsunami Modeling 125
7.3.3 Tsunami Runup Predictions 126
7.3.4 Tsunami Warning Systems and Emergency Management 127
7.3.5 Landslide-Generated Waves 127
7.4 Long Wave Oscillations 127
7.5 Storm Surge 128
7.5.1 Regional and Local Storm Surge 129
7.5.2 Wind Setup 130
7.5.3 Pressure Setup 132
7.5.4 Long-Term Fluctuations 132
7.5.5 Features of Hurricane Storm Surge 133
7.5.6 Storm Surge Modeling 134
7.6 Wave Setup 134
7.7 Sea Level Rise 136
7.7.1 Sea Level Rise Components 136
7.7.2 Sea Level Rise Measurements 136
7.7.3 Land Uplift/Subsidence 136
7.7.4 Relative Sea Level Rise Projections 137
7.8 Climate Change Impacts 138
7.8.1 Background 138
7.8.2 Arctic Sea Ice Cover 139
7.8.3 Hurricanes 139
7.8.4 Storm Surge and Extreme Waves 140
7.8.5 Implications for Coastal Engineering Practice 140
7.9 Coastal Flood Levels 140
7.9.1 Flood Construction Level 141
7.9.1.1 Methodology 141
7.9.1.2 Tide Level and Storm Surge 142
7.9.1.3 Relative Sea Level Rise 142
7.9.1.4 Wave Runup 142
7.9.2 Base Flood and Design Flood Elevations 143
7.9.3 Dike Crest Elevation 143
7.9.4 Tsunami Flood Level 143
7.9.5 Probability of Coastal Flooding 144
7.9.6 Consequences of Coastal Flooding 145
7.10 Coastal Currents 147
Problems 148
8 Coastal Structures 151
8.1 Introduction 151
8.1.1 Categories of Structure 151
8.2 Seawalls 153
8.2.1 Linear Wave Theory 153
8.2.2 Miche-Rundgren and Sainflou Methods 154
8.2.3 FEMA Formulation for Plunging Breakers 156
8.2.4 Goda Formulation 156
8.2.5 Related Impermeable Structures 158
8.3 Rubble-Mound Structures 159
8.3.1 Predictions of Armor Stability 161
8.3.1.1 Hudson Equation 161
8.3.1.2 Van der Meer Equations 162
8.3.1.3 Damage Progression 162
8.3.2 Alternate Rubble-Mound Configurations 164
8.3.3 Wave Runup and Overtopping 164
8.3.3.1 Wave Runup 164
8.3.3.2 Wave Overtopping 165
8.4 Slender Structures 165
8.4.1 Development of Morison Equation 166
8.4.2 Morison Equation for a Sinusoidal Flow 167
8.4.3 Application to Pipelines and Piles 169
8.4.4 Drag and Inertia Coefficients 172
8.4.5 Lift Force 172
8.4.6 Extensions to the Morison Equation 174
8.5 Large Structures 176
8.5.1 Introduction 176
8.5.2 Vertical Circular Cylinder 176
8.5.3 Other Configurations 179
8.6 Floating Structures 180
8.6.1 Introduction 180
8.6.2 Recap of a Single-Degree-of-Freedom System 180
8.6.3 Added Mass 182
8.6.4 Hydrodynamic Analysis 183
8.6.5 Random Waves 185
8.7 Wave Impact Forces 185
8.8 Floating Breakwaters and Bridges 186
8.8.1 Transmission Coefficient 187
8.8.2 Hydrodynamic Analysis 189
8.8.3 Mooring System Analysis 190
8.8.3.1 Static Mooring Analysis 191
8.8.3.2 Dynamic Mooring Analysis 192
8.9 Other Loads 193
8.9.1 Foundation Loads and Stability 193
8.9.2 Earthquake Loads 193
8.9.3 Vessel Impact, Ice Impact, and Debris Loads 194
8.9.4 Wind Loads 195
8.10 Renewable Energy Infrastructure 195
8.10.1 Background and Criteria 195
8.10.2 Wind Energy 196
8.10.3 Wave Energy 196
8.10.4 Tidal Energy 197
8.10.5 Current Turbines 197
8.10.6 Ocean Thermal Energy Conversion 198
Problems 198
9 Coastal Processes 201
9.1 Introduction 201
9.2 Coastal Forms 201
9.3 Sediment Properties 205
9.3.1 Sediment Size 205
9.3.2 Cohesive Sediments 206
9.3.3 Sediment Composition and Density 206
9.3.4 Porosity and Bulk Density 206
9.3.5 Fall Velocity 207
9.4 Threshold of Sediment Motion 208
9.4.1 Unidirectional Flow 208
9.4.2 Waves 210
9.5 Beach Characteristics 212
9.6 Sediment Transport Processes 213
9.6.1 Onshore-Offshore Transport 214
9.6.2 Longshore Transport 215
9.6.3 Estimates of Longshore Transport 216
9.6.4 Sediment Sources and Sinks 217
9.6.5 Shoreline Evolution Models 218
9.6.6 Transport of Cohesive Sediments 220
9.7 Bluff Erosion 220
9.8 Scour 221
9.8.1 Scour Depth Predictions 221
9.8.2 Scour Protection 222
9.9 Mitigation of Erosion and Accretion 222
9.9.1 Beach Erosion 222
9.9.2 Sediment Accretion 224
9.9.3 Coastal Entrances 224
9.10 Approaches to Shoreline Protection 224
9.10.1 Coastal Resilience 225
9.10.2 Traditional Methods 225
9.10.3 Nature-Based and Hybrid Methods 226
9.11 Coastal Restoration 228
9.12 Coastal Management 228
Problems 229
10 Mixing Processes 231
10.1 Introduction 231
10.2 Advection-Diffusion Equation 232
10.2.1 One-Dimensional Equation 232
10.2.2 Two- and Three-Dimensional Equations 233
10.3 Solutions to the Advection-Diffusion Equation 233
10.3.1 Diffusion Equation with Instantaneous Point Source 233
10.3.2 Advection-Diffusion Equation with Instantaneous Point Source 234
10.3.3 Effect of a Plane Boundary 235
10.3.4 Spatially Distributed Source 235
10.3.5 Time Varying Point Source 236
10.3.6 Numerical Models 236
10.4 Diffusion and Dispersion Coefficients 238
10.5 Stratified Flows 238
10.6 Mixing in Estuaries 239
10.6.1 Categories of Estuaries 239
10.6.2 Mixing Mechanisms 239
10.7 Estuarine Flushing 240
10.7.1 Flushing Parameters 240
10.7.2 Selected Cases of Flushing 242
10.8 Salinity Intrusion in Estuaries 243
10.9 Turbulent Jets and Plumes 244
10.9.1 Jet and Plume Behavior 244
10.9.2 Diffusers 246
Problems 247
11 Design of Coastal Infrastructure 249
11.1 The Design Process 249
11.2 Accounting for Uncertainty 250
11.2.1 Kinds of Uncertainty 250
11.2.2 General Approach 250
11.2.3 Extensions to the Approach 251
11.3 Selected Design Tools 251
11.3.1 Probability of Failure 251
11.3.2 Risk Assessment and Management 253
11.3.3 Permits and Approvals 255
11.3.4 Decision-Making and Option Selection 256
11.3.5 Optimization Models 256
11.4 Aspects of the Design of Coastal Structures 257
11.4.1 Modes of Failure 257
11.4.2 Design Criteria 257
11.4.3 Design Loads and Load Factors 259
11.4.4 Detailed Design 259
11.5 Design of Harbors and Marinas 261
11.5.1 Design Considerations 261
11.5.2 Acceptable Wave Climate 262
11.5.3 Navigation 263
11.5.4 Ice Cover and Icing 263
11.5.5 Ports 264
Problems 264
12 Coastal Modeling 267
12.1 Overview 267
12.2 Numerical Models 268
12.2.1 Kinds of Models 268
12.2.2 Computational Methods 268
12.3 Model Laws 269
12.3.1 Dimensional Analysis 270
12.3.2 Similarity 270
12.3.3 Defining Relationships and Governing Equations 271
12.3.4 Scale Effects 271
12.3.5 Reynolds Number Disparity 271
12.4 Laboratory Models in Coastal Engineering 271
12.4.1 Short-Wave Models 272
12.4.2 Long-Wave Models 272
12.4.3 Coastal Structures 273
12.4.4 Sediment Transport 273
12.5 Laboratory Facilities 275
12.5.1 Kinds of Facilities 275
12.5.2 Wave Flumes 275
12.5.3 Wave Basins 277
12.6 Wave Generation and Measurement 278
12.6.1 Wave Generator Control 278
12.6.2 Instrumentation and Measurement Techniques 278
12.7 Field Measurements 278
Problems 280
A Reference Solutions 281
B List of Symbols 283
C Physical constants 291
References 293
Index 297
1
Introduction
1.1 Scope of Coastal Engineering
Coastal engineering relates to the solution of engineering problems in the coastal environment. It concerns, for example: the design of coastal structures such as breakwaters and seawalls, the design of harbors and marinas, understanding and addressing the consequences of sea level rise and coastal flooding, the assessment and control of sediment erosion and accretion, the design of shoreline protection schemes, and the assessment and controlled discharge of pollutants in the ocean environment.
Coastal engineering is a branch of civil engineering. Neighboring civil engineering subdisciplines that may be relevant to a coastal engineering project include hydraulic engineering, geotechnical engineering, structural engineering, and earthquake engineering. Neighboring disciplines include ocean engineering that relates to engineering projects in the ocean, uninfluenced by proximity to a coastline and often associated with offshore oil and gas recovery; naval architecture that relates to the design and operation of ships and marine vessels; and oceanography that relates to the scientific study of the oceans. Some subdisciplines of the sciences, such as nearshore oceanography and coastal geology, overlap with aspects of coastal engineering.
Several decades ago, Weigel (1964) and Ippen (1966) developed what may be regarded as foundational texts in coastal engineering. Subsequently, several texts on coastal engineering that have been available and widely used include Sorensen (2006), Sawaragi (2011), Reeve et al. (2018), and Kamphuis (2020), with each one providing different areas of emphasis. Many other texts focus on particular aspects of coastal engineering, such as marina design, port engineering, and coastal processes, or on topics within related disciplines such as ocean engineering and hydraulic engineering. In addition, various design manuals and guides that are relied upon in coastal engineering practice include the Coastal Engineering Manual (2002) and its predecessor the Shore Protection Manual (1984), the Rock Manual (2007), the Federal Emergency Management Agency's (FEMA) Coastal Construction Manual (2011), and the EurOtop Manual (2018).
1.2 Outline of Book
Since ocean waves are usually the primary environmental consideration in coastal engineering, it is customary that a major part of a coastal engineering text relates to a description of waves. In this context, the chapter titles of the book are as follows:
- Introduction
- Regular Waves
- Wave Transformations
- Random Waves
- Winds
- Wave Predictions
- Long Waves, Water Levels, and Currents
- Coastal Structures
- Coastal Processes
- Mixing Processes
- Design of Coastal Infrastructure
- Coastal Modeling
More specifically, summaries of these chapters are given below.
Chapter 2, Regular Waves, describes the treatment of regular waves - that is, periodic waves that propagate over a horizontal seabed without a change in form. This chapter focuses on the development and application of linear wave theory.
Chapter 3, Wave Transformations, considers the transformation of waves associated with changes in water depth and with obstacles in the flow. Thus, the chapter treats wave shoaling, wave refraction, wave diffraction, wave reflection including standing waves, wave transmission, wave attenuation, wave breaking, and wave runup at a shoreline.
Chapter 4, Random Waves, recognizes the random nature of waves and distinguishes between the short-term variability of individual waves over a few hours and the long-term variability of different storms over several years, typically leading to design wave conditions with a specified return period.
Chapter 5, Winds, which serves as a prelude to Chapter 6, gives attention to descriptions of a wind climate, approaches to accessing and analyzing wind data needed for wave hindcasting, and a description of the wind field in a hurricane.
Chapter 6, Wave Predictions, describes the prediction of waves, with a focus on a simplified approach to wave hindcasting that provides estimates of wave conditions on the basis of available wind data. Other forms of wave prediction that are mentioned include ship waves and laboratory-generated waves.
Chapter 7, Long Waves, Water Levels, and Currents, outlines long waves, which include tides and tsunamis, and coastal flooding water levels and their components, which include storm surge and sea level rise. This chapter also indicates the impacts of climate change on coastal engineering practice and concludes with a summary of the kinds of currents that may be encountered.
Chapter 8, Coastal Structures, summarizes various categories of coastal structure and approaches to estimating wave loads on structures and wave interactions with structures. The kinds of structures considered include seawalls, rubble-mound structures, slender-member structures, large structures, and floating structures. This chapter also provides descriptions of the analysis of floating breakwaters and floating bridges and an outline of loads other than wave loads that may act on a coastal structure. The chapter concludes with a description of ocean-related renewable energy infrastructure.
Chapter 9, Coastal Processes, begins with an outline of the variety of coastal forms that may be encountered. It then describes in turn coastal sediments, the conditions for the onset of sediment movement under currents and waves, the movement of sediments near shorelines including sediment transport along beaches, bluff erosion, and scour, mitigation measures for addressing unwanted sediment erosion or accretion, approaches to shoreline protection, including reliance on nature-based methods, coastal restoration, and, finally, an introduction to coastal management.
Chapter 10, Mixing Processes, which is a primary topic of environmental fluid mechanics, describes fundamental solutions to the advection-diffusion equation and summarizes related topics that include stratified flows, mixing in estuaries, and jets and plumes.
Chapter 11, Design of Coastal Infrastructure, provides an introduction to the design process and approaches to accounting for uncertainty and outlines selected design tools including probability of failure analyses, risk assessment and management, permitting and approval requirements, and decision-making in design. It then summarizes selected design considerations with respect to coastal structures, including their modes of failure, design criteria, and aspects of detailed design. Finally, the chapter discusses the design of harbors and marinas, with attention given to available criteria for acceptable wave climate in marinas and to navigational considerations.
Chapter 12, Coastal Modeling, summarizes in a general way numerical modeling associated with various coastal engineering phenomena. It then outlines the underlying principles of model laws, describes different kinds of laboratory models used in coastal engineering, and provides descriptions of laboratory facilities, instrumentation, and measurements. The chapter concludes with a summary of field measurements relevant to coastal engineering.
1.3 Example Projects
In order to provide an appreciation of the breadth of coastal engineering practice, four generic example projects are now presented, along with an indication of the range of issues that may require consideration within each of these. (Any specific terminology that is used here is defined subsequently within the text.)
1.3.1 Coastal Flooding
The first generic project relates to an assessment of coastal flooding along a shoreline and the design of flood protection infrastructure. Figure 1.1 shows a coastal dike in Richmond, BC, used here as a basis for identifying key design parameters and associated issues.
The dike design entails the selection of the dike's crest elevation and its sectional properties (e.g. crest width, seaward and landward slopes, rock size, vegetation, .) and a consideration of drainage and pump systems. The design is influenced by maximum water levels due to a combination of tides, sea level rise, storm surge and waves, and/or, if relevant, river flooding or tsunami flooding; a consideration of the probability and extent of any flooding in the context of uncertainty, risk, return period, and design life; wave runup and overtopping; and, finally, potential habitat enhancements, climate change impacts, permitting and approval requirements, and land use requirements. While Figure 1.1 indicates the case of a coastal dike, related coastal flooding projects may involve a seawall or other coastal defense along a shoreline, and a consideration of hurricane-prone areas for which storm surge is a major issue.
Figure 1.1 Coastal dike example project.
1.3.2 Coastal Structure Design
A second generic example relates to the design of different types of coastal structure. Figure 1.2 illustrates four types of structure: a seawall, rubble-mound shoreline protection, a piled pier, and a floating structure, with the figure used as a basis for identifying key design parameters and associated issues.
Common to all these are assessments of tides, water levels...
