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Overview
After explaining beaches as dynamic ecosystems, Pilkey and Cooper assess the harm done by dense oceanfront development accompanied by the construction of massive seawalls to protect new buildings from a shoreline that encroaches as sea levels rise. They discuss the toll taken by sand mining, trash that washes up on beaches, and pollution, which has contaminated not only the water but also, surprisingly, the sand. Acknowledging the challenge of reconciling our actions with our love of beaches, the geologists offer suggestions for reversing course, insisting that given the space, beaches can take care of themselves and provide us with multiple benefits.
Product Details
| ISBN-13: | 9780822375944 |
|---|---|
| Publisher: | Duke University Press |
| Publication date: | 11/21/2014 |
| Sold by: | Barnes & Noble |
| Format: | eBook |
| Pages: | 256 |
| File size: | 44 MB |
| Note: | This product may take a few minutes to download. |
About the Author
J. Andrew G. Cooper is Professor of Coastal Studies in the School of Environmental Sciences at the University of Ulster. He and Pilkey are coauthors (with William J. Neal and Joseph T. Kelley) of The World's Beaches: A Global Guide to the Science of the Shoreline and coeditors of Pitfalls of Shoreline Stabilization. Well known for his advocacy of nonintervention on shorelines and his work on beaches and coasts worldwide, Cooper lives in the town of Coleraine in Northern Ireland.
Read an Excerpt
The Last Beach
By Orrin H. Pilkey, J. Andrew G. Cooper
Duke University Press
Copyright © 2014 Duke University PressAll rights reserved.
ISBN: 978-0-8223-7594-4
CHAPTER 1
THE END IS NIGH!
ALL OVER THE GLOBE, beaches are moving landward. Where the trappings of humans are absent, the fact that a beach is retreating is neither evident nor of particular concern. But where people have built houses, condominiums, roads, and other structures next to the shoreline, beach retreat becomes beach erosion. This is of great concern to many people, particularly coastal dwellers who value their property. In efforts to hold the shoreline still, today's society is engaged in a costly and ultimately futile battle. On one side is the coastal engineering fraternity and on the other are the inexorable forces of nature. Many beaches on developed coasts have been transformed into long, thin engineering projects on which engineers hold sway until a storm comes along or budgets are squeezed. Ironically, these engineered strips of sand that we call beaches were once a precious natural environment that has been destroyed in a misguided view of the good of humanity.
The hands of humans are very clearly on the beaches of the world. Many of our actions are fairly benign—we swim, fish, sunbathe, stroll, or just enjoy the view, the sea breezes, and the smells of the sea. But we also dump trash and discharge our waste pipes onto beaches. We rake them to "clean them up," drive on them, and mine them for minerals, gravel, and sand. We bulldoze them to make "dunes" to protect houses, pump or truck sand around the beach to "improve" it, and build walls and breakwaters of various types to block waves and hold the sand in place.
NATURAL BEACHES AND HOW THEY WORK
Beaches are things of great beauty. We have only to think of the huge numbers of people who walk on beaches regularly or those who make the long journey to the seaside just to sit and watch the waves breaking, to understand the close relationship between people and beaches. Whether we stare hypnotically at the waves, stroll on the sand looking for seashells, or even brave the waves and get into the water, people all over the world have their own love affairs with beaches. Maybe it is the feeling of nature at work, the thrill of being at the edge of the land, or even the sense of freedom provided by the wide-open spaces.
Maybe it is beaches' dynamic nature that we find fascinating. Why is it that waves can cause cliffs to collapse and push huge boulders around as if they were pebbles, and yet beaches made up of tiny sand grains persist month to month, year to year, century to century? Even the casual observer can't fail to notice that beaches change with time. One day a beach may be steep, a week later, gentle; sometimes there is an abundance of sand, sometimes very little. People often return to a favorite childhood beach to find that it is quite different from what they remember. There are lots of changes to observe and contemplate, and perhaps that is part of the appeal of the beach—it is an ever-changing canvas that is seldom the same from one day to the next. As we will see, it is this ability to change that allows beaches to survive in a hostile environment while solid features, such as cliffs, seawalls, and jetties collapse.
CHANGING BEACHES
Runkerry Strand, on the rugged north coast of Northern Ireland, is a fine sandy beach that is particularly popular among dog walkers in the summer. It is dangerous to swim there, even for anyone prepared to brave the cold waters, because of strong rip currents running directly offshore. Come the winter, however, and walkers are confronted by a beach covered in boulders and pebbles. The rip currents are gone and, instead, the waves break strongly on a newly formed offshore bar. Thanks to the advent of the wet suit, surfers can enjoy the winter waves breaking on the bar.
This complete change in the beach is the result of stronger winter waves, packed with energy from distant storms in the North Atlantic. The sand is unable to withstand the force of the waves and the bottom currents they form, so it is transported offshore, exposing an underlying beach of cobbles (grapefruit-sized rocks) and boulders. When carried offshore, the sand is deposited and molded by the waves into a bar. The bar then helps to break the energy of the waves, and the rest of the energy is absorbed by the cobble beach. On the other hand, in the summer when waves are smaller, the sand is pushed onshore and is welded to the high part of the beach, covering the cobbles. The waves lose most of their energy by breaking close to shore, and the remaining energy is transformed into rip currents.
A similar winter-summer change occurs on outer Cape Cod beaches in the United States. During the winter, the higher waves form currents that carry beach sand offshore, where three distinct sandbars often are formed. Come summertime, the beaches widen as the smaller waves move sand ashore, causing the sandbars to disappear.
Runkerry and outer Cape Cod beaches, like many others, routinely go through this cycle of sand movement in response to the seasonal wave changes. When it was first recognized by Francis Shepard in the 1950s on the beach in front of the Scripps Institution of Oceanography in La Jolla, California, the two forms of the beach were called summer and winter profiles. Subsequently, however, it was realized that some beaches changed a lot seasonally while others changed only a little. In the early 1980s, researchers Don Wright of the Virginia Institute of Marine Science and Andy Short of the University of Sydney discovered that the shape of beaches was related to how they absorbed or dissipated the energy carried in the waves. To absorb the energy of large waves, beaches needed to be wide and gently sloping, allowing the energy of the breaking waves to be absorbed over a broad surface. For lesser waves, the energy could be absorbed on a narrow surface as waves swashed up the beach. They termed the two end stages dissipative for broad beaches and reflective for narrow beaches.
By comparing dozens of beaches in Australia and the United States, Wright and Short found a fairly consistent relationship—the bigger the waves, the larger the volume of the available sand, and the finer the sand, the more dissipative the beach. Although this was an elegant explanation of how many beaches work, no classification made by humans can do justice to a complex natural system like a beach. In fact, it is fair to say that no two beaches operate in the same way.
In 2009, Carlos Loureiro was working on his Ph.D. on beach behavior in southwest Portugal. That winter he noted that the popular surfing beach at Cabanas Velhas lost all its sand. Contrary to expectations (and Wright and Short's theory), however, the sand didn't return the following summer. The reason seemed to be that the winter of 2009 was exceptionally stormy. Storm followed storm and the excess energy in the waves caused rip currents that remained active for long periods, carrying the sand farther offshore than normal. The sand, having been stripped away into deeper water, will take longer to return—and indeed might never return.
It isn't just waves that cause beaches to change shape. Changes may also occur because of a difference in the supply of sand to a beach. Five Finger Strand, a rural beach in County Donegal, Ireland, has seen dramatic changes in the past two decades. This beautiful sandy area near Ireland's remote northern tip began to experience erosion of the beach and its huge, grass-covered dunes in 1995. These dunes were more than 100 feet (30 meters) high and more than a mile (1.6 kilometers) wide. Over the next few years, this erosion continued until the seaward face of the dunes was a 65-foot-high (or about 20 meters) scarp of bare sand and the beach lost its sand entirely, revealing an underlying surface of pebbles and boulders. The local people and county council were concerned by these changes, and researchers at the nearby University of Ulster set out to assess what was happening.
The answer was quite unexpected. The change began when an inlet of an estuary at one end of the beach swung to the north. Normally, the tides and waves at the mouths of inlets build small deltas called tidal deltas. But the small shift to the north was enough to separate the inlet from its delta. Consequently, the forces of the tides and waves began to build a new delta. The sand to build this new delta was drawn in from the adjacent beach and dunes, which ultimately was the cause of the severe erosion of Five Finger Strand. In the meantime, the old delta was freed from the tidal currents that had formed it and held it in place, and it began to be moved by the waves, building up other beaches next to it. So as one beach was being severely eroded because the sand was used to build a new tidal delta, a second beach was accreting, using the sand from the old offshore tidal delta.
A study of old maps and air photos shows that this pattern of change had happened before and that the inlet had regularly moved between the two positions. The time frame of shifting was, however, in the region of 25 to 30 years, so this had seemed to be an unprecedented event to most people. But in reality it was just part of a predictable long-term cycle. In 25 to 30 years, the beach at Five Finger Strand should come back. There is some uncertainty about the future, however, because in the last few decades a new element controlling beach evolution has come into play: sea-level rise.
Although the sea has only risen a foot (0.3 meters) over the last 100 years or so, that amount can have a real impact on shoreline retreat on very gently sloping coasts. For example, the average slope of the lower coastal plain of North Carolina is one foot of rise in elevation for every 2,000 feet (610 meters) of horizontal distance. Thus, at least in theory, a 1-foot sea-level rise should push the shoreline back 2,000 feet. On the Outer Banks of North Carolina, the slope is closer to a ratio of 1:10,000, and the shoreline should move back nearly 2 miles (3.2 kilometers). This amount of shoreline retreat will definitely happen, but it will be a delayed action carried out on a multi-decadal time frame. This is because there is a big pile of sand (a barrier island) in the way.
Marine geologist Andy Green was mapping the seabed on South Africa's east coast in the early 2000s when he discovered some remarkable features. Running for tens of miles were low ridges arranged in the same characteristic shapes of a dune line along a modern coastline—but in a water depth of 200 feet (60 meters)! These submerged sand bodies turned out to mark the positions of a former sandy shoreline formed when the sea level was 200 feet below the present and several miles seaward of today's shoreline. The new technology of multibeam bathymetric mapping of the seafloor allows the seabed to be charted in unprecedented detail, which allowed for this amazing discovery.
The sand bodies were preserved as lines of beach rock—a rock created by cemented beach sand that forms on the edge of tropical and subtropical beaches. The dune sands adjacent to the beaches were cemented as well, much as some dune sands in the Bahamas are cemented today. The beaches on the South African seabed were drowned about 11,500 years ago when the sea level jumped 50 feet (15 meters) in just 300 years.
Submerged preserved beaches are now recognized as being quite common—those in the waters off Australia, Brazil, and Florida are as deep as 390 feet (120 meters) below the present sea level. On Florida's Gulf Coast, geologist Al Hine discovered whole sets of easily recognizable forms at 230 feet (70 meters) below sea level. These were once barrier islands, and now they are visible to the multibeam mapper, preserved in minute detail.
The significance of these preserved shorelines and barrier islands, besides offering proof of sea-level change, is that they must have survived as a surf zone moved over them with the rising sea level. The waves in a surf zone could easily destroy these features even in their cemented state, so the sea-level rise must have been rapid. This means that the sea level at that moment in geologic time must have experienced a sudden jump in the rate of rise. A jump might mean 3 feet (1 meter) in two decades (admittedly an educated guess at best). Such a rapid rise would have been caused by a surge in glacier melting or a failure of glacial dams that suddenly released a very large mass of water.
Radiocarbon dating of the beach rock on these abandoned shorelines confirms what we knew from coral-reef records on the steep slopes around the island of Barbados: the sea level has risen by more than 325 feet (100 meters) over the past 20,000 years as the earth moved out of the last ice age and into the warm period that geologists call an interglacial. We live in an interglacial at the moment. In fact, over the last 2 million years, the sea level has risen and fallen numerous times as the world's water resources have switched from the ocean to ice caps and glaciers and back again. The submerged beaches, however, also faithfully preserve the shapes of former coastlines and show us that those ancient beaches were quite similar to their modern equivalents. Beaches in nature are almost indestructible.
But it isn't just cemented beaches that tell us of former shorelines. Sometimes the evidence is less direct. Trawlers in Europe's North Sea and on Georges Bank off New England regularly haul up remains of land animals, many of them now extinct—for example, mastodons, saber-toothed tigers, mammoths, and elk. This shows that what is now the seabed was once land.
About 50 years ago off the East Coast of the United States, geologists discovered that under a thin cover of marine sands there would sometimes be mud, and even peat, with the remains of plants and animals (like oysters) that we associate with salt marshes. Clearly these deposits had formed in coastal marshes right at sea level when it was much lower.
Trawlers in Maine had long been bringing up arrowheads and spear-points in their nets. These caught the attention of archaeologists who discovered that the ancient tools were trawled from a specific site, which prompted marine geologist Joseph Kelley to wonder why the tools were there. Quickly he discovered a submerged landscape preserved on the seafloor at a depth of about 65 feet (20 meters), where early inhabitants of Maine had lived. There were beaches where those inhabitants had made stone tools, fished, and collected shellfish.
Collectively, all of these investigations on the seafloor have enabled geologists to begin to understand what happens to beaches when the sea level rises over thousands of years. Some beaches are stranded and left behind on the seabed, and some roll over the seabed and are reworked into modern beaches, while others are smeared over the seabed, leaving behind a thin layer of sand. Whatever its fate in a rising sea, a beach can usually survive.
Many factors are at work in determining what happens to a beach as the sea level rises. These include the rate and amount of sea level rise, the nature of the beach materials, whether any new material is being added to the beach from rivers and at what rates, where the beach is located (tropics to poles), and the type of beach (e.g., barrier island, mainland beach, pocket beach, or rocky shoreline). The important thing is that beaches have been able to survive more than 325 feet (100 meters) of sea level rise since the last ice age.
STORMS, FLOODS, TSUNAMIS—THE BIG HITTERS
It is one thing to see the evidence of coastal change in the geological record over thousands of years, but we also know that coasts change significantly over much shorter time frames. The passage of a single storm can cause dramatic changes. Countless elderly residents of coastal communities can relate changes on beaches over their lifetimes (changes that sometimes prove to have magnified over time). Many of the most dramatic transformations on beaches occur during big storms, hurricanes, and tsunamis.
The tsunami in the Indian Ocean on Boxing Day in 2004 left many vivid impressions of dramatic changes to beaches. Beaches that had been crowded with tourists were transformed in an instant into a wasteland of debris. In Banda Aceh, the worst-hit coast in Sumatra, geologists recorded the complete loss of beaches and adjacent villages, as the coastline was eroded by more than 325 feet (100 meters) overnight. It seemed as if the coast was utterly destroyed. However, Singapore researcher Soo Chin Liew and colleagues subsequently presented a remarkable set of satellite images that shows the coast before and immediately after the tsunami. The devastation was remarkable, as the beach had disappeared and large swaths of vegetation had been destroyed by the tsunami waves. Yet an image taken in 2006 (only 13 months after the tsunami) shows a newly formed wide sandy beach, admittedly 325 feet (100 meters) landward of the former beach, but nonetheless a coast that hides all vestiges of the recent tragedy, at least on the scale of satellite imagery. From the perspective of the beach, this served to demonstrate its remarkable resilience to devastating waves—the sand that had been on the beach must have been lost offshore only temporarily as it quickly came onshore after the tsunami passed.
Hurricane Sandy (widely known as Superstorm Sandy) struck the New Jersey coast in October 2012. After Hurricane Katrina, it was the second costliest hurricane to strike the United States in terms of damage to property. All along the Jersey shore and its barrier islands, beachfront homes were flooded, the beaches (almost all of which were artificial replenished beaches) were eroded, and several feet of sand were deposited on roads and in formerly neatly tended yards. Within a matter of a few weeks, most of that sand had been bulldozed back to the beach.
(Continues...)
Excerpted from The Last Beach by Orrin H. Pilkey, J. Andrew G. Cooper. Copyright © 2014 Duke University Press. Excerpted by permission of Duke University Press.
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Table of Contents
Foreword viiPreface xi
Acknowledgments xvii
1. The End is Nigh! 1
2. Selling the Family Silver: Beach-Sand Mining 24
3. Indefensible: Hard Structures on Soft Sand 41
4. Patch-up Jobs: Beach Replinishment 70
5. The Plastisphere: Trash on the Beach 95
6. Tar Balls and Magic Pipes 107
7. Stuck in a Rut: Driving on the Beach 123
8. The Enemy Within: Beach Pollution 139
9. The International Dimension of Beach Destruction 160
10. The End is Here 175
Appendix 1 199
Appendix 2 203
Bibliography 207
Index 233
What People are Saying About This
"We're all used to lying on beaches and zoning out—but it turns out that if we want those beaches to be there much longer we better stand up and make our voices heard. This is fascinating new information about one of the planet's most beloved ecosystems."
"The Last Beach is a must-read for anyone interested in the plight of the world's beaches. This brave confrontation with coastal engineers, coastal planners, developers, politicians, and beachfront property owners lays bare their adverse impact on the world's beaches."