Advanced Series on Ocean Engineering - Volume 14 COASTAL STABILIZATION Richard Silvester John R C Hsu \v? World Scientific
Contents PREFACE xv 1 INTRODUCTION 1 /. / Coastal Environment 2 J.2 State of Beach Erosión 5 1.3 Engineeríng Approach 6 1.3.1 Conventional Methods, 6 1.3.2 NewConcept, 7 2 WAVES 9 2.1 Wave Generation 10 2.1.1 Wind, 10 2.1.2 Mechanisms of Generation, 17 2.1.3 Wave Characteristics, 23 2.2 Wave Forecasting 26 2.2.1 Wave Statistics, 28 2.2.2 Wave Forecasting for FAS, 30 2.2.3 Average Spectra, 37 2.2.4 Wave Forecasting for Finito Depths, 38 2.2.5 Waves from Tropical Cyclones, 42 2.2.6 Waves in Dispersal Áreas, 45
viii Contents 2.3 Wave Kinematics 48 2.3.1 Progressive Waves, 51 2.3.2 Standing Waves, 63 2.3.3 Short-Crested Waves, 68 2.3.4 Mass Transport, 78 2.4 Wave Transformations 83 2.4.1 Shoalíng, 84 2.4.2 Refraction, 85 2.4.3 Diffraction, 92 References 98 3 BEACH PROCESSES 107 3.1 Orígin of Beaches and Dunes 109 3.1.1 Coastal Terminology, 111 3.1.2 Sand on Beaches, 112 3.1.3 Blowouts, 113 3.2 Wave Climate J16 3.2.1 Storm Waves, 118 3.2.2 Swell, 121 3.3 Sediment Movement Beyond Breaker Une 126 3.4 Lateral Movement in Suri Zone 129 3.4.1 The Swell-Built Profile, 129 3.4.2 The Síorm-Built Profile, 130 3.4.3 Bar Characteristics from Large Wave Tank Tests, 136 3.4.4 Bar Characteristics from Prototype Measurements, 150 3.4.5 Return of the Bar, 156 3.4.6 Múltiple Bar Profiles, 160 3.5 Longshore Drift 160 3.5.1 Littora! Drift Calculations, 163 3.5.2 Longer-Term Variations in Drift, 167 3.6 Effects of Tides 169 3.6.1 Magnitude of Tides, 170 3.6.2 Influence on Shoreline Processes, 170 3.7 Eífects of Ocean Currents 174 3.8 Estuarine Condftions 175 3.9 Cohesive Soils 178 3.10 Shíngle Beaches 184
Contents x 3.77 Marine Cliffs 186 References 92 4 ENGINEERING ASPECTS OF COASTAL GEOMORPHOLOGY 199 4.7 Geomorphology of Coasts 200 4.1.1 Configuration of Beaches, 200 4.1.2 Barrier Beaches, 204 4.1.3 Engineering Significance, 205 4.2 Crenulate Shaped Bays 206 4.2.1 Bay Orientations, 206 4.2.2 Logarithmic Bay Shape, 212 4.2.3 Parabolic Bay Shape, 215 4.2.4 Verification of Parabolic Shapes, 221 4.2.5 Practical Applications, 223 4.2.6 Indentation Ratio, 229 4.2.7 Bay Extremities, 231 4.2.8 Bay Under Storm Attack, 239 4.2.9 Bays with Small Gaps, 241 4.3 Physiographic Unifs 244 4.3.1 Isolated Bays, 246 4.3.2 Contour Spreading, 246 4.3.3 Shoals, 248 4.3.4 End Conditions, 249 4.3.5 Continental Patterns, 251 4.4 Barrier Beaches 253 4.4.1 Historical Review, 258 4.4.2 Mode of Spit Construction, 263 4.4.3 Erosive Conditions, 264 References 266 5 COASTAL DEFENSE 271 5.7 Cause of Erosión 274 5.1.1 Main Causes, 274 5.1.2 Basic Requirements, 276 5.2 Dune Stabilization 277 5.3 Previous Solutions 278 5.3.1 Seawails and Revetments, 279 5.3.2 Groins, 284 5.3.3 Offshore Breakwaters, 289 5.3.4 Perched Beaches, 292 5.3.5 Beach Renourishment, 294
x Contents 5.4 New Concept 302 5.4.1 Headland Control, 302 5.4.2 Possible Applications, 304 5.5 Shingle Beaches 312 5.6 Cohesive Soils 321 5.6.1 Waves and Currents, 322 5.6.2 Shoreline Profiles and Mode of Erosión, 322 5.6.3 Previous Solutions, 323 5.6.4 New Solutions, 325 5.7 Cliff Recession 326 5.8 Sea Level Bise 328 5.8.1 Tide Measurements, 329 5.8.2 Sea Leve! Changa Over Time, 330 5.8.3 Causes of Sea Level Change, 331 5.8.4 Engineering Impacts, 332 5.8.5 What to Do If Anything, 333 References 334 6 APPLICATIONS OF HEADLAND CONTROL 340 6.1 Design of Headlands 342 6.2 Salient Behind Single Offshore Breakwafer 344 6.2.1 Salient Growth, 344 6.2.2 Dimensionless Ratios, 346 6.2.3 Salient Planform, 351 6.2.4 Bay Shape Application, 357 6.3 Sfraight Shoreline 359 6.4 Eroding Embayment 361 6.5 Barrier Island and Spit 362 6.6 Alternative to Groin Field 363 6.7 Modifícation to Offshore Breakwaters 366 6.8 Beach Renourishment 367 6.9 Beach Downcoast of Harbor Construction 370 6.9.1 Straight Shoreline, 371 6.9.2 Bay in Dynamic Equilibrium, 372 6.9.3 Bay in Static Equilibrium, 376 6.10 Artificial and Recreational Beaches 377
Coníents xi 6. i 1 Man-Made Islands 380 References 383 7 EFFECTS OF MARITIME STRUCTURES 386 7. / Scour Due to Normal Waves 388 7.2 Scour Due to Shorí-Crested Waves 389 7.2.1 Model Evidence of Scour, 391 7.2.2 Field Evidence of Scour, 401 7.2.3 General Comments, 433 7.3 Scour at Jip of Breakwafer 434 References 438 8 ALTERNATIVES TO NORMAL BREAKWATERS 440 8.1 Berm Breakwaters 441 8.1.1 Berm Breakwater Profiles, 442..1,2 Other Considerations, 444 8.2 Barríer Beach Breakwaters 444 8.2.1 Prevention of Sand Removal, 446 8.2.2 Existing Cases, 447 8.2.3 Suggested Barrier Beach Breakwaters, 450 8.3 Geotextile Construction 457 8.3.1 Characteristics of Geotextile Units, 459 8.3.2 Design of Units, 461 8.3.3 Mortar Mix, 467 8.3.4 Costs, 472 8.3.5 Logistics, 474 8.3.6 Applications, 475 8.4 Submerged Platform Breakwaters 476 8.4.1 Theory and Experimental Verification, 477 8.4.2 Hydrodynamics of Platform, 479 8.4.3 Applications, 480 References 482 9 BYPASSING MECHANISMS 486 9.7 Dredging 487 9.2 Land Dredging Plañís 488 9.3 Trucking 488
xü Contents 9.4 Effect of Jetties 488 9.4.1 Effect of Littoral Drift and Size of Bar, 489 9.4.2 Effect of Tidal Flow, 491 9.4.3 Bar Welding and Beach Recession, 492 9.5 WeirJefties 493 9.5.1 Action of Weirs, 494 9.5.2 Modeling, 497 9.5.3 Prototypes, 497 9.6 JetPumping 498 9.7 Sand Fluidizafíon 499 9.8 Wave Refíection 500 9.8.1 Wave Phenomena, 500 9.8.2 Model Tests, 502 9.8.3 Applications, 508 9.8.4 Effect on Navigation, 511 9.9 Upcoast Accretion 513 References 5 15 10 WHAT DIRECTION COASTAL ENGINEERING 518 70.7 Introduction 518 10.2 Coste 579 70.3 Need for Reappraisal 520 10.4 Waves 521 10.5 Beach Processes 522 10.6 Geomorphology of Coasfs 523 10.7 Coastal Defense 524 10.7.1 Dune Stabilízation, 524 10.7.2 Previous Defense Solutions, 525 10.7.3 Headland Control, 528 10.7.4 Cohesive Soils, 529 10.7.5 Shingle Beaches, 530 10.8 Effects of Maritime Structures 530 10.9 Alternative to Normal Breakwaters 530 10.9.1 Berm Breakwater, 531 10.9.2 Barrier Beach Breakwater, 532 10.9.3 Geoíextiles, 533 10.9.4 Submerged Platform Breakwaters, 534
Contents xiii 10. W Bypassing Mechanisms 534 10.10.1 Dredging, 534 10.10.2 Weir Jetties, 535 10.10.3 Jet Pumping, 536 10.10.4 Sand Fluidization, 53ó 10.10.5 Wave Reflection, 53ó 10.10.6 Upcoast Accretion, 537 JO. U Data Collection 537 References 539 APPENDIX A TABLE OF FUNCTIONS OF d/l0 541 INDEX 561