Coastal Geomorphology E-Book

Eric C. F. Bird

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 936

Veröffentlichungsjahr: 2011

Beschreibung

Coastal Geomorphology, Second Edition is a comprehensive and systematic introduction to this subject and demonstrates the dynamic nature of coastal landforms, providing a background for analytical planning and management strategies in coastal areas that are subject to continuing changes.

This introductory textbook has been completely revised and updated, and is accompanied by a website which provides additional illustrations, global examples, case-studies and more detailed and advanced information on topics referenced in the book, together with explanations of terminology, annotated references and research material.

Leseprobe

Contents

Preface to the second edition

Acknowledgements

List of Figures

List of Tables and Panels

1 Itroduction

1.1 Coastal geomorphology

1.2 Terminology

1.3 Ancient coastlines

1.4 Coastline morphology

1.5 Coastline length

1.6 Coastal evolution

1.7 Changing coastlines

1.8 Summary

2 Coastal processes

2.1 Introduction

2.2 Waves

2.3 Tides

2.4 Storm surges

2.5 Tsunamis

2.6 Currents

2.7 Nearshore water circulation

2.8 Wind action

2.9 Other processes

2.10 Modelling coastal processes

2.11 Summary

3 Land and sea level changes

3.1 Introduction

3.2 Mean sea level

3.3 Causes of sea level change

3.4 Measuring changes of level

3.5 Correlation and dating of former coastlines

3.6 Emerged coastlines

3.7 Submerged coastlines

3.8 Sea level variations

3.9 Late Quaternary sea level changes

3.10 Modern sea level changes

3.11 Recent changes of land and sea level

3.12 Future sea level changes

3.13 Summary

4 Cliffs

4.1 Introduction

4.2 Cliff evolution

4.3 Cliff morphology

4.4 Cliff weathering in cold climates

4.5 Cliffs and bluffs on humid tropical coasts

4.6 Cliff dissection

4.7 Outlines in plan of cliffed coasts

4.8 Coastal landslides

4.9 Rates of cliff recession

4.10 Summary

5 Shore platforms

5.1 Shore processes

5.2 Shore platforms

5.3 Plunging cliffs

5.4 Summary

6 Beaches

6.1 Introduction

6.2 Beach sediments

6.3 Evolution of beaches

6.4 Provenance of beach sediments

6.5 Weathering of beach material

6.6 Beach rock

6.7 Nearshore processes

6.8 Beach morphology

6.9 Beach outlines in plan

6.10 Beach outlines in profile

6.11 Beach morphodynamics and beach states

6.12 Use of models

6.13 Beach compartments

6.14 Beach budgets

6.15 Tracing beach sediment flow

6.16 Lateral grading

6.17 Prograding beaches

6.18 Beach ridges

6.19 Cheniers

6.20 Beach lobes

6.21 Summary

7 Beach erosion

7.1 Introduction

7.2 The multiple causes of beach erosion

7.3 Effects of artificial structures on beaches

7.4 Beach nourishment

7.5 Summary

8 Spits, barriers and bars

8.1 Introduction

8.2 Spits

8.3 Tombolos

8.4 Cuspate and lobate spits

8.5 Cuspate and lobate forelands

8.6 Coastal barriers and barrier islands

8.7 Intertidal sandfiats

8.8 Bars and troughs

8.9 Sand shoals

8.10 Ripples

8.11 Sandstone reefs

8.12 Summary

9 Coastal dunes

9.1 Introduction

9.2 Foredunes

9.3 Backshore cliffing of dunes

9.4 Parallel dunes

9.5 Blow-outs and parabolic dunes

9.6 Transgressive dunes

9.7 Cliff-top dunes

9.8 Dunes on shingle

9.9 Rates of dune movement

9.10 Dune calcarenite

9.11 Machair

9.12 Coastal dunes in the humid tropics

9.13 Old and new dunes

9.14 Dune sandrock

9.15 Dune lakes

9.16 Summary

10 Intertidal wetlands

10.1 Introduction

10.2 Intertidal morphology

10.3 Sources of intertidal sediments

10.4 Mudfiats

10.5 Intertidal vegetation

10.6 Sea-grass beds

10.7 Salt marshes

10.8 Mangroves

10.9 Freshwater swamps

10.10 Summary

11 Estuaries and lagoons

11.1 Introduction

11.2 Rias

11.3 Fiords

11.4 Fiards

11.5 Calanques

11.6 Sharms and sebkhas

11.7 Estuaries

11.8 Coastal lagoons

11.9 Summary

12 Deltas

12.1 Introduction

12.2 Delta components

12.3 Deltaic processes

12.4 The Mississippi delta

12.5 Delta outlines

12.6 Delta evolution

12.7 Delta shores

12.8 Summary

13 Coral and algal reefs

13.1 Introduction

13.2 Coral reefs

13.3 Origin of coral reefs

13.4 Rates of growth

13.5 Fringing reefs

13.6 Barrier reefs

13.7 Atolls

13.8 Emerged coral reefs

13.9 Islands on coral reef platforms

13.10 Algal and other biogenic reefs

13.11 Summary

14 Future coasts

14.1 Introduction

14.2 Greenhouse effect and sea level rise

14.3 General effects of a rising sea level

14.4 Effects of a changing climate

14.5 Effects on cliffs and shore platforms

14.6 Effects on beaches, spits and barriers

14.7 Effects on coastal dunes

14.8 Effects on intertidal wetlands

14.9 Effects on estuaries and lagoons

14.10 Effects on deltaic coasts

14.11 Effects on coral and algal reefs

14.12 Conclusion

14.13 Summary

References

Index

Copyright C

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Library of Congress Cataloguing-in-Publication Data

Bird, E. C. F. (Eric Charles Frederick), 1930-Coastal geomorphology:an introduction / Eric Bird. — Second editionp. cm.Includes bibliographical references and index. ISBN 978-0-470-51729-1 (cloth) — ISBN 978-0-470-51730-7 (pbk.)1. Coasts. I. Title.GB451.2.B55 2007 551.457–dc22 2007039323

British Library Cataloguing in Publication Data

A catalogue record for this book is available from the British Library

ISBN 978-0-470-5′729-1 (HB) ISBN 978-0-470-51730-7 (PB)

Preface to the Second Edition

This is the second edition of an introduction to the study of coastal geomorphology that provides a background for people interested in learning how coastal features (such as cliffs, beaches, spits or deltas) have developed, and how they are changing. It is intended for people coming newly to the subject, for students and for ecologists, engineers, planners and developers concerned with the coast.

Coastal geomorphology is a broad subject that has developed rapidly, and now generates about 400 publications each year. It has become difficult to produce an introductory textbook, for topics covered in chapters in previous textbooks have subsequently been dealt with at book length, as in the Wiley Coastal Morphology and Research series. A comprehensive treatise on coastal geomorphology would now require a massive volume that would certainly be too expensive for students. This book provides a concise introduction that draws attention to unsolved problems and matters on which there are differences of opinion, and gives references to more detailed research work. The coverage is necessarily selective, and somewhat personal, drawing upon my studies of coasts in various parts of the world over the past five decades.

The book discusses the shaping of coastal landforms and examines the changes that are taking place in response to coastal processes. It demonstrates the dynamic nature of coastal landforms and provides a background for analytical planning and management decisions in coastal areas subject to continuing change. One of the problems in producing an introductory textbook on coastal geomorphology is the need to be selective in quoting examples of coastal features and process relationships, bearing in mind that most readers come from Britain, Europe, North America or Australasia, and are likely to be more interested in local and accessible examples. Reference can be made to The World’s Coasts Online, produced by Springer in 2003, for examples from various other coasts. Place names in England are identified by county, in the USA and Australia by state, and elsewhere by country.

The book begins with an introduction to concepts and terminology, and the factors that have affected coastal evolution and coastline changes (Chapter 1). This is followed by a discussion of waves, tides, currents and other nearshore processes (Chapter 2), and a study of the effects of land and sea level changes, notably the Holocene marine transgression, which has played a major part in shaping modern coastlines and can be regarded as a unifying theme in coastal geomorphology (Chapter 3). Cliffs are discussed in Chapter 4 and the shore platforms that border them in Chapter 5. Chapter 6 deals with the origin of beaches and the changes taking place on them, and Chapter 7 with the beach erosion problem. Spits, barriers and bars are discussed in Chapter 8 and the formation of coastal dunes in Chapter 9. Intertidal wetlands, including mudfiats, salt marshes and mangroves, are dealt with in Chapter 10, followed by estuaries and lagoons, including other inlets (rias, fiords, fiards, calanques, sharms and sebkhas) in Chapter 11. Chapter 12 considers deltas produced by deposition at river mouths, and Chapter 13 deals with the various kinds of reef built by corals, algae and other organisms on the shore and in coastal waters. The final chapter reviews the response of coastlines to the predicted world-wide rise in sea level, resulting from global warming by the enhanced greenhouse effect, and documented by the Intergovernmental Panel on Climate Change (2007). A list of references provides a guide to more detailed information, including many pre-2000 publications that remain relevant.

Supplementary material, including a classification of coastal landforms (which appeared as an appendix in the first edition), will appear on this book’s companion website www.wileyeurope.com/college/bird, along with a glossary, a bibliography, case studies and many more illustrations. It will also be useful to refer to two recent reference works, the Encyclopedia of Geomorphology (Goudie, 2004) and the Encyclopedia of Coastal Science (Schwartz, 2005).

Eric Bird

Acknowledgements

I am greatful to Juliet Bird for advice during this revision of the text, and to Chandra Jayasuriya and Blaise Vinot for help with maps and diagrams. Lew Ward provided help with computer processing. I would also like to thank the staff of the Earth Sciences Library in the University of Melbourne for assistance in the course of exploring the coastal literature.

Eric BirdBlack Rock, March 2007

List of Figures

1.1Coastal terminology1.2Chalk coast, Seven Sisters, Sussex1.3Coastline changes1.4Nero’s villa, Anzio, Italy2.1Wave terminology2.2Wave refraction2.3Refracted waves, Tasmania2.4Breaking waves2.5Rip currents, Woolamai Beach, Australia2.6Shore zones and tide ranges2.7Displaced beach rock, Port Hedland, Australia3.1Temple of Serapis, Italy3.2Notches, Phang-nga Bay, Thailand3.3Emerged beach, Falmouth Bay, Cornwall3.4Emerged coastlines, south-east South Australia3.5Australia Last Glacial coastline3.6Holocene sea level curves3.7Giant’s Rock, Porthleven, Cornwall3.8Gulf of Bothnia uplift3.9Gulf of Bothnia new land3.10Galeolaria on Dromana pier, Port Phillip Bay, Australia3.11Caspian Sea changes of level3.12Subsiding coasts4.1Chalk cliff, Birling Gap, Sussex4.2Abrasion notch, Cape Liptrap, Victoria, Australia4.3Grooves and buttresses on chalk cliff, Sussex4.4Breakaway, Black Ven, Dorset4.5Diagram of Black Ven and Cains Folly, Dorset4.6Honeycomb weathering4.7Cracking cliff, Demons Bluff, Victoria, Australia4.8Escarpment cliff, Ballard Down, Dorset4.9Seaward dip on cliff, Boat Harbour, Tasmania4.10Slope-over-wall profile, Golden Cap, Dorset4.11Structural ledges, Wonboyn, New South Wales4.12Degraded chalk cliff, Samphire Hoe, Kent4.13Steep coast, Lynmouth, Devon4.14Slope-over-wall profile, Flamborough Head4.15Evolution of periglacial slope-over-wall profile4.16Slope-over-wall profile, Dodman Point4.17Quartzite buttress at Boswinger, Cornwall4.18Humid tropical bluffs, NE Australia4.19The Lion’s Den, Cornwall4.20Huntsman’s Leap, Pembrokeshire4.21Dissection of promontory4.22Green Bridge of Wales, Pembrokeshire4.23Collapse of London Bridge, Australia4.24Twelve Apostles, Victoria, Australia4.25Stacks at Pistol River, Oregon4.26Whale Chine, Isle of Wight4.27Dissection of Anak Krakatau, Indonesia4.28Lulworth Cove, Dorset4.29Nullarbor coast, South Australia4.30Toppling cliff near Port Campbell, Australia4.31Undercliff, Blackgang, Isle of Wight4.32Boulder festoon, Golden Cap, Dorset4.33Slumping cliffs, Covehithe, Suffolk4.34Profiles of retreating cliff, Lake Erie5.1Cliff and shore platform features5.2Shore potholes, Rye, Australia5.3Wave quarrying, Tasmania5.4Karstic weathering, Sorrento, Australia5.5Shore platform types5.6Broad Ledge, Kimmeridge, Dorset5.7Corridor planation, New South Wales5.8High tide shore platform, Otways, Australia5.9Abrasion platform, Cape Liptrap, Australia5.10Old Hat island, New Zealand5.11Mushroom rock, Sorrento, Australia5.12Cliff and shore platform, Jubilee Point, Australia5.13Plunging cliff, Slieve League, Ireland6.1Grain size analysis6.2Gains and losses from a beach6.3Beach supplied with fiuvial sediment, Australia6.4Prograded beach, Malindi, Kenya6.5Shoreward drifting; erosion sequence6.6Loe Bar, Cornwall6.7Slapton Ley, Devon6.8Shelly beach, Barra, Scotland6.9Slowinski National Park, Poland6.10Spilling dune sand, Yanakie, Victoria, Australia6.11Shingle ridges, Hoed, Denmark6.12Prograded beach, Porthoustock, Cornwall6.13Lateral grading, Chesil Beach, Dorset6.14Beach rock, Lombok, Indonesia6.15Seasonal variations, Black Rock Beach, Australia6.16Curved beach, Port Phillip Bay, Australia6.17Wind resultants6.18Asymmetrical beaches, Victoria, Australia6.19Drift and swash beaches, Westernport Bay, Australia6.20Shingle beach with cusps, Ringstead, Dorset6.21Microcliff, Ninety Mile Beach, Australia6.22Upper and lower beach, Dungeness, Kent6.23Tracer experiment Portland, Australia6.24Beach compartments, Lyme Bay, Dorset6.25Lateral grading, Hawke Bay, New Zealand6.26Prograding beaches, Streaky Bay, Australia6.27Lakes Entrance, Gippsland, Australia6.28Changes at Sandringham Harbour, Australia6.29Esker emergence, Gulf of Bothnia6.30Beach ridges, Hailuoto, Finland6.31Prograding sandy shore, Tasmania6.32Cheniers, Van Diemen’s Gulf, Australia6.33Formation of migrating beach lobes7.1The Bruun rule7.2Erosion, Ninety Mile Beach, Australia7.3Lagos Harbour, Nigeria7.4Drifting dunes, Encounter Bay, South Australia7.5Wave refiection by sea wall7.6Sea wall with no beach, Black Rock, Australia7.7Sediment budget, Rhode Island, USA7.8Beach nourishment, Mentone, Victoria, Australia8.1Shaping of recurved spit8.2Blakeney Point, Norfolk8.3Changes at the end of Blakeney Point, Norfolk8.4Dungeness Spit, Washington State, USA8.5Cape Cod, United States8.6Trailing spits, North Queensland, Australia8.7Trailing spit, Lindholm, Denmark8.8Tombolo, Bruny Island, Tasmania8.9Middle Brighton Harbour, Australia8.10Sea of Azov spits, Russia8.11Evolution of Dungeness, Kent8.12Recession of a coastal barrier8.13Gippsland coast barrier sections, Australia8.14Sand bars, Rosebud, Victoria, Australia9.1Evolution of parallel foredunes9.2Cliffed dune, Somers, Victoria, Australia9.3Dune swale and wind eddy9.4Formation of blow-out9.5Blow-outs; parabolic dunes; transgressive dunes9.6Mobile coastal dunes, Algoa Bay, South Africa9.7Cliff-top dunes9.8Dune calcarenite cliffs and shore platforms10.1Intertidal zone, Westernport Bay, Australia10.2Tidal divide, Westernport Bay, Australia10.3Sea-grass terraces, Port Phillip Bay, Australia10.4Dissected salt marsh Bay of Saint Michel, France10.5Evolution of salt marsh creek10.6Perranarworthal Creek, Cornwall10.7Tidal creek sections10.8Spartina terrace, Poole Harbour, Dorset10.9Evolution of mangrove-fringed salt marsh terrace10.10Advancing mangroves, Westernport Bay, Australia10.11Receding mangroves, Westernport Bay, Australia10.12Evolution of mangrove terrace and creeks10.13Chenier in mangroves, New Caledonia11.1Evolution of Carrick Roads, Cornwall11.2Fiord, Milford Sound, New Zealand11.3Calanque, Gozo, Malta11.4Sebkha, King Sound, NW Australia11.5Estuary zones11.6Estuarine meanders11.7Estuary threshold, Wagonga Inlet, Australia11.8Drake’s Estero, California, USA11.9Coastal lagoon zones11.10Lagoon of Venice, Italy11.11Ringköbing Fiord (coastal lagoon), Denmark11.12Murray-mouth lagoons, Australia11.13Deltas, Gippsland Lakes, Australia11.14Segara Anakan, Indonesia11.15Segmentation of coastal lagoon11.16Reedswamp encroachment sequence11.17Reedswamp, Gippsland Lakes, Australia11.18Shoreline erosion, Gippsland Lakes, Australia12.1Nile delta, Egypt12.2Subdelta lobes, Mississippi delta, USA12.3Changing outline, Iles Dernières, Mississippi delta12.4South Pass jetties, Mississippi delta, USA12.5Mississippi, Ebro, Niger, São Francisco deltas12.6Historical changes, Danube delta, Romania12.7Cimanuk delta, Indonesia12.8Changes on the Fal delta, Cornwall12.9Microcliff, Fal delta, Cornwall12.10Delta coast nearshore profiles13.1Fringing coral reef, Bali13.2Fringing reef structure13.3Barrier reef stratigraphy13.4Kapingamarangi atoll, Caroline Islands13.5Notch and visor, Isle of Pines, New Caledonia13.6Sand cay, Maldives13.7Evolution of cay and low wooded island14.1Changes with sea level rise14.2Boulders protect eroding cliff, Fairlight Bay, Sussex14.3Artificial coastline, Litorale di Pellestrina, Italy14.4Mangrove responses to a sea level rise14.5Mamberamo delta, Irian Jaya, Indonesia14.6Tilting reefs, Uvea, New Caledonia

List of Tables and Panels

Panel 1.1Coastline or shoreline?Table 1.1Geological columnPanel 1.2Comparisons of coasts of similar geology, latitude and aspectsTable 1.2Coastal dimensionsPanel 2.1CurrentsPanel 2.2Global variations in tide rangeTable 3.1Features of emerging coastsTable 3.2Features of submerging coastsTable 4.1Average rates of cliff recessionTable 6.1Beach grain size categoriesPanel 6.1Granulometric analyses of beach sedimentPanel 7.1Indications of beach erosionPanel 7.2The causes of beach erosionTable 9.1Components of dune calcarenitePanel 14.1Problems in coastal geomorphology

1

Introduction

1.1 Coastal geomorphology

More than half the world’s population lives in coastal regions, and many people visit the coast frequently. Most come for seaside recreation, but some also wonder about the origins of coastal scenery. A walk along the shore or a coastal footpath prompts questions about how such features as cliffs, rocky outcrops, beaches and dunes formed, and how and why they are changing. A coastal journey is likely to encounter estuaries, lagoons and river deltas that have evolved over longer periods, and it soon becomes clear that sea level has not always been where it is now.

Coastal geomorphology deals with the shaping of coastal features (landforms), the processes at work on them and the changes taking place. Coastal geology is concerned with the rock formations and structures seen in cliff and shore outcrops, and the sediments that have been deposited in coastal regions. It provides the background for coastal geomorphology.

Apart from incidental comments by classical Greek and Roman observers and by Leonardo da Vinci, the first systematic attempts to explain coastal landforms were by 19th century scientists such as Charles Lyell and Charles Darwin, and the pioneer American geomorphologist William Morris Davis. While a great deal of work was done in the 20th century on various parts of the world’s coastline, particularly in Europe and North America, it is only in the past few decades that coastal research has become widespread, and there is still plenty of opportunity for original contributions.

Coastal geomorphology has several themes, each of which will be discussed in this book.

(a) The shaping of landforms in relation to geology, processes, variations in climate and the relative levels of land and sea.

(b) Coastline changes measured over specified periods, with analyses of their causes.

(c) Nearshore processes and responses, particularly on beaches.

(d) Evidence of geological history, notably changes in land and sea level and climatic variations.

(e) The sources and patterns of movement of coastal sediment.

(f) The array of weathering processes in the coastal zone.

1.2 Terminology

The coast consists of a number of zones (Figure 1.1). The shore is the zone between the water’s edge at low tide and the upper limit of effective wave action, usually extending to the cliff base. It includes the foreshore, exposed at low tide and submerged at high tide, and the backshore, extending landward from the normal high tide limit, but inundated by exceptionally high tides or by large waves during storms. The shoreline is strictly the water’s edge, migrating to and fro as the tide rises and falls.