P U B L I C I S S U E S I N E A R T H SCIENCE 
Front cover: The Cape Hatteras lighthouse stands behind a seawall of sandbags that temporarily 

stabilized the eroding shore; wave action destroyed the seawall soon after it was built. The erosion 

of North Carolina's chain of barrier islands has prompted a National Research Council committee to 

recommend that this historic lighthouse be relocated. 
PUBLIC ISSUES IN EARTH SCIENCE 

By 

S. Jeffress Williams, 

Kurt Dodd, and 

Kathleen Krafft Gohn 

U.S. G E 0 L 0 G I CAL SURVEY CIRCULAR 10 7 5 
U.S. DEPARTMENT OF THE INTERIOR 

BRUCE BABBITT, Secretary 

U.S. GEOLOGICAL SURVEY 

Gordon P. Eaton, Director 

Any use of trade, product, or firm names in this publication is for descriptive 

purposes only and does not imply endorsement by the U.S. Government 

First Printing 1991 

Second Printing 1992 

Third Printing 1995 

UNITED STATES GOVERNMENT PRINTING OFFICE: 1995 

Free on application to the 

U.S. Geological Survey 

Information Services 

Box 25425, Federal Center 

Denver, CO 80225 

Library of Congress Cataloging in Publication Data 

Williams, S. Jeffress. 

Coasts in crisis I by S. Jeffress Williams, Kurt Dodd, and Kathleen K. Gohn. 

p. em.- (Public issues in earth science) (U.S. Geological Survey circular; 1075) 

Includes bibliographic references. 

Supt. of Docs. no.: I 19.4/2:1075 

1. Coast changes. I. Dodd, Kurt. II. Gohn, Kathleen K. III. Title. IV. Series. 

V. Series: U.S. Geological Survey circular; 1075 

GB45l.2.W55 1991 

333.91 '7-dc20 90-22800 

CIP 
F 0 R E W 0 R b iii 

FOREWORD 

This publication is the first in a planned series, Public Issues in Earth Science, 

published by the U.S. Geological Survey. Its purpose is to describe the importance 

of the earth sciences in an issue vital to our society: the deterioration of our ocean 

and Great Lakes shorelines and wetlands. 

The personal effect of this crisis on people living in coastal regions is enormoushomes are destroyed, savings lost. The effect on coastal communities and recreation 

and fishing industries is devastating-businesses are destroyed, resources and jobs 

lost. The long-term repercussions on Federal, State, and local agencies and the 

insurance industry can be huge. According to the 1990 census, the most dramatic 

population growth over the past decade occurred in the coastal States; continuation 

of this trend will increase the stress on our coastal environments. 

In this book, the authors describe our Nation's varied coastal environments and 

the natural processes and human actions that are constantly modifying them. 

Ignorance of these processes exacerbates the tragic collisions between people and 

nature-such as Hurricane Hugo last year in South Carolina, which left thousands 

homeless and destroyed billions of dollars of property. We are still learning the 

lesson that Francis Bacon expounded almost four centuries ago: "Nature to be 

commanded must be obeyed." To obey and command nature, however, we must 

improve our scientific understanding of its forces and processes; only then can we 

address the crisis now facing coastal communities. 

The earth sciences provide information critical to understanding and resolving 

this crisis. Through cooperative investigations, the earth-science community can 

contribute to a better understanding of coasts, their dynamic processes, and their 

responses to human intervention. As the primary Federal earth-science agency, the 

U.S. Geological Survey is the lead organization in the collection, interpretation, and 

dissemination of earth-science data and analyses-critical first steps in helping to 

resolve the crisis facing our coastal environments and communities. 

Dallas L. Peck 

Director 
iv C 0 A S T S I N C R I S I S 

PACIFIC 

OCEAN 

ANNUAL SHORELINE CHANGE 

- Severely eroding 

Moderately eroding 

Re latively stable 

Uncolored U.S. shoreline indicates no data are available; 

data are also lacking for parts of Alaska, as well as Puerto 

Rico, U.S. Virgin Islands, and the U.S. Pacific Islands, 

which are not shown on this map. 

ALASKA 

0 

GULF OF 

ALASKA 

300 MILES 

I I I 

I I I 400 KILOMETERS 

All 30 coastal States are experiencing erosion along their coastlines. (Modified from Dolan and oth 
COASTS IN CRISIS v 

~ke~ Superior 

Lake 

HAWAII 

c:1 QKauai 

Oah@Honolulu 

~~aui 

PACIFIC OCEAN 

1 I Tw~ r---,~~----~ 

: I I ~KILOMETERS 

GULF OF MEXICO 

500 MILES 

I I 

700 Kl LO METERS 

;, Coastal erosion and accretion: U.S. Geological Survey National Atlas.) 

ATLANTIC 

OCEAN 
vi C 0 A S T S I N C R I S I S 

CONVERSION FACTORS 

For readers who wish to convert measurements from the metric system of units to the inchpound system, the conversion factors are listed below. 

Multiply By To obtain 

Length 

millimeter 0.039 inch 

centimeter 0.394 inch 

meter 3.281 foot 

kilometer 0.621 mile 

Area 

square kilometer 0.386 square mile 

Volume 

liter 0.264 gallon 

cubic meter 1.308 cubic yard 

A simple rule of thumb for approximate conversions: 1 inch equals about 25 millimeters, or 

about 2.5 centimeters; 1 yard equals about 1 meter; 1 quart equals about 1 liter. 
T A B L E 0 F C 0 N T E N T S vii 

Table of Contents 

Foreword iii 

Introduction 1 

Perception and Reality 1 

People vs. Nature 2 

The Key: Earth-Science Information 2 

Types of Coasts 3 

Rocky Shores 3 

Sandy Beaches 3 

Coastal Wetlands 5 

Coral Reefs 5 

Coastal Change 6 

Natural Processes 6 

Waves, Tides, and Weather 6 

Water-Level Changes 8 

Coastal Vegetation 9 

Local Conditions 10 

Mainland Beaches {Southern California) 10 

Barrier Beaches {Southeastern United States) 10 

Wetlands {Coastal Louisiana) 11 

Lake Shores {Lake Erie) 12 

Human Intervention 13 

Sediment Starvation 14 

Pollution 15 

Sediment Trapping 15 

Coastal Degradation 16 

Water-Level Changes 17 

Coastal Conflicts 18 

Ocean City-An Urbanized Barrier Island 18 

Hurricane Hugo-Storm Devastation 20 

Isles Dernieres-Eroding Barrier Islands 22 

Boston Harbor-Centuries of Pollution 25 

Conclusions-Earth-Science Challenges and Opportunities 26 

Further Reading 30 

Federal Agencies With Regulatory or Research Responsibilities for Our Coasts 32 

Graphic design and layout: Leslie S. Weissleader 

Photo Credits: Peter W. Barnes, Michael Chrzastowski, Robert Dolan, Robert N. Ginsburg, 

Gregory S. Gohn, Bruce Richmond, Rafael W. Rodriguez, Asbury H . Sallenger, Jr., U.S. Army 

Corps of Engineers, U.S. Fish and Wildlife Service, Leslie S. Weissleader, S. Jeffress Williams 

.. 
viii C 0 A S T S I N C R I S I S 

When we think of a coast, most of us envision: 

a secluded get-away 

(Actually, 50 percent of the U.S. population lives within an hour's drive 

of a coast.) 

with a broad stretch of sand 

(In the late 1970's, $64 million was spent 

replenishing Miami Beach with 13 

million cubic meters of sand.) 

with teeming wildlife and 

succulent shellfish 

(One-third of the Nation's shellfish beds are 

closed or restricted because of pollution.) 

or perhaps vast marshes 

and wetlands 

(Louisiana is losing as much as 100 square 

kilometers of wetlands each year, an area 

the size of the District of Columbia.) 
COASTS IN CRISIS 1 

INTRODUCTION 

Our coasts are reaching a crisis. Threats to 

coasts and to coastal communities are growing 

as development, recreation, and waste disposal 

activities increase, often in conflict with longterm natural processes. Other threats to our 

coasts, such as sea-level rise and reduction in 

sediment supply, result from global warming 

and the damming of rivers. 

The impending crisis of our coasts stems 

from misconceptions about what coasts areand from actions based on those misconceptions. Differences between our perceptions 

and the reality of coasts intensify the conflicts 

between people and nature. These conflicts 

will worsen as the coastal population expands 

and competing uses of the recreational, wildlife, shipping, and mineral resources of coasts 

increase. 

PERCEPTION AND REALITY 

We think of land as stable and treat it as a 

permanent asset. For most land, this premise 

is reasonable because land generally changes 

very slowly. Although tectonic and geologic 

processes, such as continental drift and erosio· 

are always at work, they usually result in vef1 

gradual changes that are barely noticeable 

during a human lifetime. 

Coasts, however, are not static; they are 

dynamic . They quickly change shape and 

location in response to natural forces and 

human activities. These forces and activities 

continually push and pull at coasts- sometimes 

in the same direction, but often in opposite 

directions. As a result, the shape of the coastline changes. Sand and other materials are 

moved onto and off of beaches by currents and 

waves. Seasonal movement of coastal materials 

creates broad summer beaches followed by 

narrow winter beaches in an annual cycle. 

During major storms, huge waves and storm 

surges can move large amounts of coastal 

sediments and can flood vast areas in a matter 

of hours. 

On a larger scale, the coast itself moves as 

it tries to achieve equilibrium with the forces 

acting on it. Barrier islands and offshore sand 

bars move landward and along the coast, driven 

by longshore currents. Headlands are eroded 

back, moving the coast inland. Sediment is 

deposited on river deltas, extending the coast 

out into the water. Coastlines also move in 

response to changes in sea level; even if the 

land remains stationary, a rise in sea level will 

move the coastline inland. 

PRUDHOE BAY, AK 

This dock facility at Prudhoe Bay shows the effects 

of northern Alaska's coastal erosion problem. Strong 

storm waves and ice action cause the erosion rates in 

the Beaufort Sea to be among the highest in the United 

States. Some barrier islands are moving landward as 

fast as 7 meters per year. These rapid erosion rates 

endanger causeways and artificial islands built for oildrilling platforms. 

• 
2 COASTS IN CRISIS 

PEOPLE VS. NATURE 

Because we treat the coast just like all 

other land-as a stable platform on which 

we can safely and easily build- some of our 

actions directly conflict with the dynamic 

nature of coasts. Other human activities, such 

as the increasing release of greenhouse gases, 

may indirectly affect our coasts through global 

warming, causing worldwide sea-level rise as 

glaciers melt. Still other actions, such as the 

damming of rivers for flood control and water 

management, may affect the stability of 

coastlines by restricting the supply of new 

sediments being carried to the coasts. 

Coastal areas 

across th e 

United States 

now have 

population 

densities 

five times the 

Nation's average. 

Conflicts between people and nature have 

always existed along the coasts. The increasing desirability and accessibility of coasts as 

places to work and live have intensified these 

conflicts greatly over the past 50 years. The 

1990 census shows that 25 of the 30 coastal 

States have had dramatic population increases 

since 1980; the largest increases were in 

Alaska (36 percent), Florida (31 percent), and 

California (24 percent). Coastal areas across 

the United States now have population densities five times the Nation's average. Currently, 

50 percent of the Nation lives within 75 kilometers of a coast; this number is projected to 

increase to 75 percent by the year 2010. As 

the coastal population grows, so does the need 

for additional facilities for transportation, 

recreation, potable water, and waste disposal. 

Pollution is already severe near large coastal 

urban areas and has hurt recreation activities 

and the fishing industry. 

Wetlands and marshes are now widely 

recognized as important but fragile parts of the 

coastal environment. Louisiana, which contains 

more than 40 percent of the tidal wetlands in 

the 48 conterminous States, is losing as much 

as 100 square kilometers of wetlands each year. 

These marshes are one of the world's most 

productive ecosystems. Their continued demise 

seriously affects migratory waterfowl, songbird 

populations, and fish and shellfish resources, as 

well as the coastal culture of Louisiana. 

In the future, the mineral potential of coastal 

sand, including its potential for gold and other 

metals, may result in another competing use of 

our coastal resources as cheaper onshore mineral supplies are exhausted. Mining coastal 

sand for heavy minerals and construction materials without a carefully designed plan may 

further stress the fragile coastal environment. 

THE KEY: EARTH-SCIENCE 

INFORMATION 

How should we deal with these competing 

needs? How can we manage the coastal crisis? 

The first step is to understand our coasts better, 

to build a solid foundation of earth-science 

data on coastal processes and evolution, and to 

identify what factors are important in quantitatively determining the location and move -

ment of coasts. Only after thorough research 

and interpretation can the critical scientific 

results be translated into practical terms and 

be incorporated into sound coastal management policies. 

This report briefly explains coasts-the types 

of coasts, the natural processes that create and 

modify them, and the human activities that 

affect them. It gives specific examples of coasts 

that are dramatically changing as a result of, 

or in conflict with, human interests and actions. 

It documents the critical need for a better understanding of our coasts through earth-science 

investigations and the collection of scientific 

data-information that is essential to Federal, 

State, and local agencies as well as to the private sector, homeowners, and other decisionmakers who wrestle with the growing crisis 

on our coasts. 
COASTS IN CRISIS 3 

TYPES OF COASTS 

Coasts are the dynamic junction of water, 

air, and land. Winds and waves, tides and currents, migrating sand dunes and mud flats, a 

variety of plant and animal life-all combine to 

form our ever-changing coasts. Their dynamic 

nature results in their great diversity. Most of 

us envision a coast as a broad stretch of sand 

with frothy surf breaking along the shore; in 

fact, many types of coasts are found within the 

United States, ranging from sandy beaches to 

rocky shores to coral reefs to coastal wetlands. 

ROCKY SHORES 

Rocky shores form on high-energy coasts 

where mountains meet the sea and at the base 

of sea cliffs. Active tectonic environments, such 

as in California, produce rocky coasts as a result 

of mountain-building processes, faulting, and 

earthquakes. Rocky coasts also form where ice 

and strong waves have effectively removed 

fine-grained sediment. In Maine and parts of 

Alaska, glaciers have scoured most of the sediment cover from the shore. In the arctic, ice 

gouging and rafting have removed sand-sized 

particles from some beaches, leaving cobbles 

and boulders. 

The rocky shores of Oregon's Pacific coastline are among the most 

dramatic in the United States. This rugged coast is geologically 

young and has not yet been smoothed by erosion. 

SANDY BEACHES 

Sandy beaches can be categorized into three 

types: mainland, pocket, and barrier beaches. 

Mainland beaches stretch unbroken for many 

miles along the edges of major land masses. 

Some are low standing and prone to flooding; 

others are backed by steep headlands. They 

receive sediment from nearby rivers and eroding 

bluffs. Examples of mainland beaches include 

coasts of the Great Lakes, northern New Jersey, 

and southern California. Pocket beaches form 

in small bays surrounded by rocky cliffs or headlands. The headlands protect the sandy alcoves 

from erosion by winter storms and strong 

currents. Pocket beaches are common in New 

England and the Pacific Northwest. Barrier 

beaches are found along the Gulf of Mexico, 

the east coast, and much of Alaska. They are 

part of complex integrated systems of beaches, 

dunes, marshes, bays, tidal flats, and inlets. 

The barrier islands and beaches are constantly 

migrating, eroding, and building in response to 

natural processes and human activities. 

Sandbridge, Virginia, is a popular beach resort south of Virginia Beach. 

Erosion rates at Sandbridge are among the highest in Virginia. 
4 COASTS IN CRISIS 

HOG ISLAND, VA 

In the late 1800's, at least five lavish hunting and 

fishing clubs were established on Virginia's barrier islands; 

one of the largest was in the town of Broadwater, on Hog 

Island. The town, located in a pine forest near the middle 

of the island, at its height had a population of about 300 

and contained 50 houses, a lighthouse, a school, and a 

church and cemetery. Erosion destroyed the lighthouse 

before 1930, and in 1933 a hurricane inundated all of Hog 

Island, destroying much of the town and killing the 

protective pine forest. By the early 1940's, all inhabitants 

had left the island. The former site of the town is now 

under several meters of water and hundreds of meters 

from the shore. 

---/---~ .. ·~·:···· / ·"' . .. ·· / ·"' .. / ·"' .. ··/ ; .. • ~ Broachfater / 

; ·' .. .. ·· / 

,. ... / __., .. _...... -·-- .. / . ' ~· .,- ·-· ~ . ~-·'·~.' ...... ·,...,r,; .. ··· 1 

(, , .. ·· I ··\ ~" ... ·· I \ , ., ·········· I ' / ' / ' / ,_, 

0 

0 

-·-·-·-

----

1963 

1955 

1928 

1852-71 

ATlANTIC OCEAN 

'2MILES 

2 KILOMETERS 

(Modified from Rice, Niedoroda, and Pratt, The coastal processes and geology: Virginia barrier islands, val. 1 (Ecosystem 

description), part B, of Virginia Coast Reserve Study conducted by the Nature Conservancy.) 
COASTS IN CRISIS 5 

COASTAL WETLANDS 

Coastal wetlands include swamps and tidal 

flats, coastal marshes, and bayous. They form 

in sheltered coastal environments often in 

conjunction with river deltas, barrier islands, 

and estuaries. They are rich in wildlife resources and provide nesting grounds and 

important stopovers for waterfowl and migratory birds as well as spawning areas and 

valuable habitats for commercial and 

recreational fish . 

Most of the Nation's coastal wetlands are in 

Louisiana, along the Mississippi River and its 

active and ancient deltas, and in Alaska, at the 

mouths of the Yukon and Kuskokwim Rivers. 

The Great Lakes and the southeastern seaboard 

are fringed by other important wetlands, such 

as Florida's Everglades. Coastal wetlands can 

be dominated by salt water, as along the gulf 

coast of Louisiana, or they can contain a complex and changing mixture of salt and fresh 

water, like the estuaries of the Chesapeake, 

Galveston, and San Francisco Bays. 

Above: In this Louisiana wetland, salt-water intrusion has killed the cypress trees. 

Right: A coral reef is a living community, which can 

easily be damaged by pollution or hurricanes. 

CORAL REEFS 

Coral reefs abound along the southern coast 

of Florida and around the Hawaiian Islands, 

Puerto Rico, the Virgin Islands, and the Pacific 

Islands. In the shallow waters off tropical isles, 

living coral organisms build reefs that provide 

important wildlife habitats and protect coasts 

from waves and storms. Healthy coral reefs are 

also an important source of carbonate sediment 

for tropical beaches. Raised coral platforms no 

longer inhabited by living coral provide coastal 

materials and form islands such as the Florida 

Keys. 
6 COASTS IN CRISIS 

COASTAL CHANGE 

Diverse and complex natural processes 

continually change coasts physically, chemically, and biologically, at scales that range 

from microscopic (grains of sand) to global 

(changes in sea level). Regional and local 

characteristics of coasts control the differing 

interactions and relative importance of these 

natural processes. Human activity adds yet 

MONTAUK LIGHTHOUSE, NY 

George Washington, as a young engineer, selected the 

site for the lighthouse at Montauk, at the eastern end of 

Long Island. He surveyed the land, estimated the erosion 

rates of the sandy bluffs, and chose a location 60 meters 

back from the cliff edge that he estimated would be safe 

from erosion for at least 200 years. His calculations were 

remarkably accurate. Between 1868 and 1972, the cliff 

retreated 21 meters, just short of the 30 meters per century that Washington had calculated. A seawall that now 

protects the lighthouse may prolong its existence beyond 

George Washington's expectation. 

another dimension to coastal change by 

modifying and disturbing, both directly and 

indirectly, the coastal environments and the 

natural processes of change. Earth-science 

research on coastal dynamics can quantify 

these changes and improve our ability to 

predict coastal responses to human actions. 

NATURAL PROCESSES 

Coastal lands and sediments are constantly 

in motion. Breaking waves move sand along 

the coast, eroding sand in one area and depositing it on an adjacent beach. Tidal cycles bring 

sand onto the beach and carry it back into the 

surf. Rivers carry sediment to the coast and build 

deltas into the open water. Storms cause deep 

erosion in one area and leave thick overwash 

deposits in another. Plants retain sediment in 

wetlands and impede movement of coastal 

dunes. Natural processes that change the water 

level also affect coastal dynamics. Taken 

individually, each natural process of coastal 

transport is complex; taken collectively, they 

create an extraordinarily intricate system that 

attempts to achieve a dynamic balance. 

WAVES, TIDES, AND WEATHER 

Winds create waves that ripple across the 

surface of lakes and seas until they break on 

the shallowing bottom and crash into the shore. 

In many areas, prevailing winds produce waves 

that consistently approach the coast at oblique 

angles. Even the slightest angle between the 

land and the waves will create currents that 

transport sediment along the shore. These 

longshore currents are a primary agent of coastal movement; they are a major causeof sand 

migration along barrier and mainland beaches. 

Tides ebb and flood in response to the gravitational attraction of the moon and sun; exceptional high and low tides occur each month when 

the sun and moon are aligned. Tides help determine where the waves break-low on the beach 

at low tide, high on the beach at high tide-and, 

therefore, where sand is deposited and removed. 
COASTS IN CRISIS 7 

Beach 

C') 

c: 

..., 

..., 

co 

~ ....... 

Rip tides, or undertow, occur along most 

beaches and can move significant amounts 

of sand offshore. 

Storm systems along coasts contain high 

winds, create large waves, and cause storm 

surges that raise water levels as much as 7 

meters above normal. Although storms are 

sporadic, they are the primary cause of beach 

erosion along many coasts. Storms carry sand 

seaward, forming offshore bars; much of this 

sand migrates landward during calm weather. 

Some areas are more storm prone than others. 

Storms often are concentrated in specific seasons; along the eastern seaboard, for example, 

hurricanes occur in the late summer and early 

fall, and storms are especially frequent during 

the winter months. These seasonal trends 

result in a general difference between the 

winter "eroding" beach and the summer 

"building" beach that is most common along 

parts of the west coast. 

Sand is transported alongshore by currents formed when waves 

strike the beach at an angle. Sand is also carried along the shore 

in a zigzag pattern by waves rushing onto the beach and back to 

the ocean. 

GALVESTON, TX 

The city of Galveston, Texas, on a low-lying barrier 

island in the Gulf of Mexico, is the site of the worst natural 

disaster ever to strike the United States. In September 

1900, a hurricane with wind speeds estimated as high as 

160 kilometers an hour raised a 6-meter storm surge that 

covered the entire island with 3-5 meters of water. At 

least 6,000 people were killed, more than 3,500 houses 

were destroyed, and a third of the city was leveled by the 

wind, waves, and wreckage. A wall of debris-streetcar 

tracks, lengths of railroad track, sections of wrecked 

houses-built up about six streets inland from the beach 

and parallel to it, saving much of the business district from 

total destruction. 

To protect the city from further disastrous hurricanes, 

Galveston and the U.S. Army Corps of Engineers raised 

the land surface by more than 3 meters and built a 

massive seawall along the entire Gulf side of the city, at a 

cost of $3.5 million-a vast sum in 1900. Later additions 

have extended the wall along the coast more than 16 

kilometers. Where no groins hold the sand, the beach has 

disappeared; beyond the western end of the wall, the 

beach has eroded back about 50 meters. In 1961 

Hurricane Carla struck the Texas coast, flooding more 

than 1.5 million acres of land and causing considerable 

damage in the parts of Galveston not protected by the 

seawall. 

Deadliest U.S. natural disasters 

1900 Galveston, Hurricane and flood More than 6,000 dead; 

Texas 3,600 houses destroyed. 

1889 Johnstown, Dam collapse and More than 2,200 dead. 

Pennsylvania flood 

1871 Peshtigo, Fire More than 1,200 dead; 2 

Wisconsin billion trees burned. 

1906 San Francisco, Earthquake and fire More than 700 dead or 

California missing; more than 10 

square kilometers of the 

city razed. 

1925 Missouri-Illinois- Tornado 695 dead. 

Indiana 
8 COASTS IN CRISIS 

Landward limit 

of coastline 

in the past 

5 million years 

location 

of coastline 

Southern extent 

of glacial ice 

20,000 years ago 

Location of 

coastline 

20,000 

years ago 

300 MILES 

I I I 

I I I 

400 KILOMETERS 

Sea level has risen dramatically since the end of the 

last ice age, about 20,000 years ago. 

WATER-LEVEL CHANGES 

In addition to the daily cycles of tides, many 

other forces lead to significant changes in water 

level. Predominantly closed bodies of water 

such as lakes expe rience dramatic water-level 

changes in response to precipitation, spring 

snowmelt, and evaporation. A prolonged period 

of wet weather in Utah in the early 1980's, for 

example, raised the Great Salt Lake's water level 

to record highs, flooding parts of Salt Lake City. 

Other local changes in water level occur 

when the land either rises or falls relative to the 

water. Along tectonically active coasts, such as 

the coast of earthquake-prone southern California, land may rise as much as 4 centimeters 

per century. In recently abandoned deltas, such 

as near the mouth of the Mississippi River, compaction of newly deposited sediment results in 

extensive land subsidence (as much as 1 meter 

per century). The Earth's crust in parts of Alaska 

and the Great Lakes area, which was pressed 

down by the weight of the massive ice sheets 

that blanketed the north during the last great 

ice age, is now rising due to the retreat of the 

glaciers. In southeastern Hudson's Bay, Canada, 

this crustal rebound is raising vast areas of land 

at rates as high as 4 meters per century; rates 

along Lake Superior's north shore reach 60 centimeters per century. 

Sea level 

has been 

ns1ng 

continuously 

over the 

last 20,000 

years. 

Global changes in sea level result from 

tectonic processes, such as the down- or upwarping of the ocean basins, or from changes in 

the total volume of water in the oceans. During 

the last great ice age, which began 36,000 years 

ago, huge amounts of ocean water were transformed into glaciers, resulting in a 100-meter 

drop in the global sea level. We are still 

emerging from that ice age, and sea level has 

been rising continuously over the last 20,000 

years; during the past century, the rate of sea 

level rise has averaged 10-15 centimeters per 

century worldwide. 

The slope of a coast is critical to determining · 

how water-level changes will affect it. Steeply 

sloping coasts experience small shifts in their 

coastlines as the water level changes; however, 

because wave action along steep coasts is 

concentrated within a narrow zone, small waterlevel increases can result in significant erosion of 
COASTS IN CRISIS 9 

bluffs or dunes. On a gently sloping coast, 

like the U.S. east coast or around the Gulf of 

Mexico, small changes in water level cause the 

coastline to shift dramatically; however, the 

gentle slope absorbs and dissipates the waves' 

energy along a broad front. 

COASTAL VEGETATION 

Rooted plants flourish along the shores of 

bays, estuaries, deltas, and other coastal environments that are protected from the full fury 

of pounding waves. Plants stabilize dunes 

through root networks. They build and 

maintain marshes by catching and retaining 

in their roots the fine sediment carried by the 

water. Their natural decay cycle further 

enriches coastal soils and sediment with 

decomposing plant matter. Differences in 

weather regimes, tidal depth, and water 

salinity determine which plant populations 

will thrive in a given coastal environment. 

A large variety of plant species occurs in 

coastal areas where tides are extreme, since 

some plants require total submergence, some 

tolerate cyclical submergence and aeration, 

and others flourish in environments that remain 

dry except at the highest tides. Diversity of 

species is greatest where water salinity is low. 

Those few plant species that live in the most 

saline water have developed ways to control 

the internal osmotic pressure of their cells. 

Freshwater marshes, like this one on Lake Michigan's coast, are subject to a wide range of water levels. 

Gradual changes in weather patterns, 

salinity, tidal action, and sea level allow normal 

plant succession to occur in protected coastal 

environments. Abrupt changes in these conditions often result in widespread destruction of 

plant communities and the loss of sediment 

being held by their roots. For example, erosion 

of barrier islands can lead to saltwater intrusion 

and increased wave action, which kills plants 

and destroys the wetlands behind the islands. 

Small vertical changes in water level shift coastlines dramatically on gently sloping coasts but cause only minor 

shifts on steep coasts. 

~+----- Shoreline shift --~ 

H her sea level 

Low coast 

Lower sea level 

Ocean basin 

Shoreline 

shift 

Mountainous 

coast 
10 C 0 A S T S I N C R I S I S 

LOCAL CONDITIONS 

While the same dynamic processes cause 

continuous change on every coast, coasts do 

not all respond in the same way. Interactions 

among the different processes and the degree 

to which a particular process controls change 

depend upon local factors. They include the 

coast's proximity to sediment-laden rivers and 

tectonic activity, the topography and composition of the land, the prevailing wind and 

weather patterns, and the configuration of 

the coastline and nearshore geometry. Earthscience research is showing that these local 

conditions determine not only the changes to 

the coast but also the type of coast produced. 

MAINLAND BEACHES 

(Southern California) 

The mainland beaches of southern California border an active tectonic region of faultbounded crustal blocks with high elevations. 

Ancient shoreline terraces hundreds of meters 

above present sea level are evidence of rapid 

and extensive crustal uplift along the coast. 

The narrow offshore continental shelf is cut by 

numerous submarine canyons and bordered by 

deep ocean basins. The weather is temperate 

year round, but winter storms often dramatically 

reshape the coast. 

The major sediment sources for the beaches of 

southern California are eroding headlands and 

adjacent beaches and, to some degree, sediment 

from local rivers in flood. The major agent of 

sediment transport along the coast is longshore 

drift, which moves the sand southward. Submarine canyons in some areas are so close to the 

shore that they intercept the longshore drift and 

funnel beach sand seaward into very deep water. 

The beaches are relatively steep, resulting in a 

narrow wave zone between high and low tide. 

This narrow zone receives the brunt of the 

waves' pounding, and movement of beach 

sediment (erosion and deposition) is concentrated within this zone. 

BARRIER BEACHES 

(Southeastern United States) 

The southeastern coast, rimmed by a series of 

barrier islands and spits, separates the mainland 

coastal plain from a wide, gently sloping offshore 

continental shelf. This generally tectonically 

stable region has a storm and hurricane season 

during the late summer to winter months; highwind events such as Hurricane Hugo, which 

came ashore near Charleston, South Carolina, 

in 1989, are not uncommon. Most rivers cutting 

through the low-lying coastal plain flow slowly 

to the sea and deposit their sand-sized sediment 

in bays and estuaries before reaching the coast. 
C 0 A S T S I N C R I S I S 11 

Storm overwash and other processes have deposited sand in complex patterns along this South Carolina barrier spit. 

The river's suspended load of finer particles 

settles out in the sounds and bays that are 

protected by barrier islands and spits. 

The major source of new sediment to the 

barrier beaches of the Southeastern United 

States is erosion of the adjacent headlands and 

beaches, whose sand generally migrates south 

as a result of longshore transport. Sand transported landward from the continental shelf also 

may contribute to the coast and nearshore sand 

budget. The gentle slope of the southeastern 

beaches results in widely separated high- and 

low-tide zones, and wave energy is absorbed 

along this broad surface. 

WETLANDS 

(Coastal Louisiana) 

The gulf coast of Louisiana includes a broad 

expanse of wetlands sheltered from the wave 

action of hurricanes and winter storms by lowlying barrier islands. Both the wetlands and 

their protecting islands have formed as a direct 

result of the shifting of the Mississippi River 

delta lobes during the past 7,000 years. The 

deltaic processes that control the movement of 

water and sediment have resulted in a system 

of complex drainage patterns, natural ridges 

and levees, and offshore barrier beaches-all 

of which restrict the advance and encroachment of salt water. 

Plant life is vital to building and maintaining 

wetlands. The coastal Louisiana wetlands are 

biologically zoned on the basis of the salinity of 

the water and the fluctuations in water depth, 

with different plant populations living in different areas. The dependence of these wetlands 

on the Mississippi River and its distributaries as 

a direct source of sediment and fresh water 

leaves them vulnerable to changes in the river 

system. Their dependence on barrier islands for 

protection against waves leaves them vulnerable 

when the barrier islands are eroded. 

An egret picks its way among cypress knees in a Louisiana wetland. 
12 C 0 A S T S I N C R I S I S 

CHICAGO, IL 

Chicago's extensive waterfront along Lake Michigan 

includes many engineering structures built 50 to 80 years 

ago to protect the city from storm waves and flooding. A 

period of high lake level in the mid-1980's exacerbated 

the deterioration of many of these aging seawalls, 

revetments, and other structures. The U.S. Geological 

Survey (USGS). in cooperation with the Illinois State 

Geological Survey, used sidescan sonar instruments to 

determine the causes and extent of the deterioration. This 

knowledge contributed potential savings of tens of 

millions of dollars to the structural repair of Chicago's 

waterfront by distinguishing areas that were still 

structurally sound from those needing repairs. Other 

USGS studies in progress provide data on the specific 

erosional processes at work, vital knowledge for those 

attempting to mitigate the damages. Water levels have 

dropped slightly since the record highs of a few years ago, 

but continuing studies have shown that those highs are 

part of the natural cycles of lake-level fluctuations in the 

Great Lakes. 

LAKE SHORES 

(Lake Erie) 

Lake Erie is the shallowest of five large 

interconnected bodies of fresh water, known 

collectively as the Great Lakes, that form part 

of our political border with Canada. The 

basins of the Great Lakes were carved by 

continental glaciers during the last great ice 

age and filled with melt waters as the glaciers 

retreated northward. 

Wave and tide action are generally limited 

in lakes because they are relatively small 

bodies of water. However, due to Lake Erie's 

size and oblong shape, communities at the 

ends of the lake, like Buffalo and Toledo, 

suffer from dangerous storm surges. These 

storm surges can quickly raise the local lake 

level by more than a meter. Though they 

may last only a few hours, surges can do considerable damage, primarily from flooding. 

Much of Lake Erie and its beaches and 

cliffs are frozen during winter, inhibiting the 

formation of storm waves and reducing 

erosion. However, during ice formation in 

early winter and during the spring thaw, ice 

processes can accelerate erosion. The spring 

rains,s nowmelt, and low evaporation rates 

cause Lake Erie's average water level in June 

to be more than 30 centimeters above the 

typical January level. Several years of abovenormal precipitation, as in the mid-1980's, 

can cause Lake Erie's water level to rise 

significantly above its long-term average, 

increasing the likelihood of flooding and 

erosion. 

Left: Parts of Chicago's protective seawall are 80 

years old and badly deteriorated. 

Above right: The heavily engineered Chicago shoreline is vulnerable to damage from Lake Michigan. 

Right: The once-wide beach at Cape May, New 

Jersey, has been stripped of its sand by longshore 

currents; the sand that would normally have replenished the beach is trapped updrift by jetties at Cape 

May inlet. 
C 0 A S T S I N C R I S I S 13 

HUMAN INTERVENTION 

Human activities add another layer of 

complexity to the natural processes of coastal 

lands and materials. These activities may have 

direct or indirect effects on our changing coasts. 

They may affect sources of new sediment to the 

coast and the movement of sediment within 

the coastal environment; they may promote 

changes in sea level, both local and global. 

People's activities are often conducted 

without an adequate understanding of coastal 

geology and processes. As a result, they can 

lead to unforeseen degradation of coasts. Even 

human actions intended to save or improve the 

coast may inadvertently increase erosion. 

Cooperative scientific investigations are starting 

to provide the crucial information needed to 

minimize the unintended effects of human 

disturbances along coasts. 
14 C 0 A S T S I N C R I S I S 

PRESQUE ISLE, PA 

About six million people per year visit the State Park 

at Presque Isle, near Erie, Pennsylvania. The park is a 

sandspit, nearly 10 kilometers long, that has built out from 

the Lake Erie shore. The narrow neck connecting it with 

the mainland is eroding as fast as 2.5 meters per year. 

Large harbor jetties built in the 1800's along the Lake Erie 

coast in Ohio may have trapped much of the sediment that 

is carried eastward by longshore currents. The U.S. Army 

Corps of Engineers has spent millions of dollars over the 

past century to stabilize the area, but the problems 

continue. In the mid-1970's, an attempt was made to 

replenish the beach on Presque Isle; unfortunately, the 

dark sand chosen as fill contained too much calcium 

carbonate, which cemented the sand particles to form an 

escarpment as much as 1 meter high. Below the sand 

scarp, the natural beach sand continues to erode. 

Recently, the Corps of Engineers has begun a project to 

construct a series of 58 segmented breakwaters at a cost of 

$30 million to protect Presque Isle. 

SEDIMENT STARVATION 

For some coastal regions, such as the Pacific 

coast, a large part of their sediment budget is 

supplied by rivers. Dams built for flood control 

and water catchment along the rivers leading 

to these coasts inhibit the transport of largegrained sediments. Lacking new material, the 

sediment-starved coasts erode and migrate inland. Damming of tributary rivers to the Mississippi River over the past 60 years has also 

reduced the movement of sediment. Studies by 

the USGS in recent years demonstrate that the 

amount of sediment carried by the Mississippi 

has been cut in half, aggravating the deterioration of Louisiana's wetlands. 

An important source of sediment to Louisiana's deltaic wetlands was periodic flooding of 

the Mississippi River, which deposited new 

material on the flood plain. Massive levees 

built along the riverbanks now contain these 

floods and eliminate the supply of sediment to 

the wetlands. As a result, the natural compaction and subsidence of the delta are no longer 

balanced by the deposition of new sediment, 

and the relative local sea level is rising as much 

as 1 centimeter per year. Sediment-laden 

water, retained by levees along the Mississippi 

River, deposits its load into deep water at the 

mouth of the delta, where most of the sediment 

is lost to the coastal environment. To counteract the effects of damming and channelization, 

the U.S. Army Corps of Engineers is building 

structures to divert fresh water from the Mississippi River to adjacent wetlands. 

Attempts to counter sediment starvation 

along severely eroding coasts have included the 

artificial replenishment of beach material by 

placing sand directly onto the beach. Beach 

nourishment is not a permanent solution and is 

expensive, but in some regions it can be cost 

effective. The lack of clean sand suitable for fill 

often limits beach nourishment programs, but 

offshore surveys can locate sand bodies for 

dredging and transport to the beach. A few 

Above left: Erosion threatens the highway along the neck 

that connects Presque Isle to the Pennsylvania shore. 

Below left: Darker sand used for beach replenishment at 

Presque Isle forms a 7-meter-high scarp. 
C 0 A S T S I N C R I S I S 15 

beach replenishment programs have had longterm positive effects; the Miami Beach replenishment done in the late 1970's at a cost of 

$64 million has already survived more than a 

decade . Typically, these nourishment projects 

are not as effective; along the east coast, half of 

the replenished beaches lasted 2 years or less. 

POLLUTION 

As the number of active landfills dwindles 

and coastal populations grow, offshore waste 

dumping and coastal pollution increase. This 

additional dumping increases the possibility of 

improper waste disposal polluting the coastal 

environment. Living coral reefs are particularly 

vulnerable to pollution, but other coastal environments suffer as well. Medical waste, including used hypodermic needles, was washed onto 

the New Jersey and New York beaches during 

the summer of 1988, resulting in an economic 

disaster for the recreation industries in the 

region. Fishing industries have also been 

severely damaged by coastal pollution; more 

than one-third of our Nation's shellfish beds are 

closed or restricted as a result of contamination. 

SEDIMENT TRAPPING 

The natural movement of sand is at best a 

nuisance for owners of beachfront property. 

When this movement results in a net loss of 

sand from the beach, the natural process may 

be considered by owners as a serious threat. 

To prevent beach loss, groins are often 

constructed out into the water. These solid 

structures impede the littoral drift of sand 

caused by longshore currents. The beach then 

expands on the updrift side of the groin; 

however, the downdrift side of the groin loses 

sand because of continuing longshore movement. Small groins may have little effect on 

sediment movement along the entire beach. 

Larger groins or jetties, such as the ones at the 

southern end of Ocean City, Maryland, and at 

Cape May, New Jersey, can lead to impressive 

retention of beach materials on the updrift side, 

but these gains must be balanced against the 

coa stal degradation on the downdrift side. 

Sediment carried out past the jetty may be 

deposited as shoals offshore in deeper water 

PRINCE WILLIAM SOUND, AK 

61 ° 

I I 

( ( 

Prince William 

Sound 

\ \ 

N 

GULF A 

OF 

ALASKA 

10 20MILES 

1--,rt --'-' -.,ro --,.r'o ~oMEmlS 

147° 

On March 24, 1989, an oil tanker struck Bligh Reef in Prince 

William Sound, Alaska, releasing more than 200 million liters 

of oil. The map above outlines the oil-spill front as it expanded 

from 1 to 8 days after the spill; it was compiled from aerial 

observations by the National Oceanic and Atmospheric 

Administration, Exxon, the U.S. Coast Guard, and the Alaska 

Department of Environmental Conservation. Bottom 

sediments studied by the USGS more than 7 weeks after the 

spill contained no clear evidence of oil pollution; possible 

traces of contamination were found near the south end of the 

Sound, but the presence of oil could not be confirmed. Much 

of the oil was carried onshore by surface currents and 

deposited along the beaches. Long-term monitoring is needed 

to assess the effect of the spill on the marine environment. 

(Modified from Carlson, P.R., and Reimnitz, Erk, 1990, 

Characterization of sample sites along the oil spill trajectory in 

Prince William Sound and the Gulf of Alaska: U.S. Geological 

Survey Open-File Report 90-39-A. 24 p.) 
16 C 0 A S T S I N C R I S I S 

At Manasquan, New Jersey, a groin has trapped sand on the updrift 

side, but the down drift beach is starved of sand. 

A series of groins at Norfolk, Virginia, interrupts the natural transport 

of sand by longshore currents. 

and removed from the active coastal sediment 

budget, further increasing downdrift erosion. 

Seawalls constructed to protect property 

along retreating beaches often exacerbate 

beach erosion. They confine the wave energy 

and intensify the erosion by concentrating the 

sediment transport processes in an increasingly 

narrow zone. Eventually, the beach disappears, leaving the seawall directly exposed to 

the full force of the waves. For example, a 

massive seawall built to protect a highway and 

beach houses along the northern New Jersey 

coast has resulted in the complete disappearance of the beach itself. 

COASTAL DEGRADATION 

Human actions that lead to the destruction 

of dune grasses and the disturbance of coastal 

landforms promote increased erosion and 

movement of beach materials. Off-road 

vehicles and foot traffic on sand dunes compact sand, destroying plant roots and animal 

burrows. Other wildlife habitats, such as 

nesting and feeding areas for shorebirds, are 

disturbed by human activity; young birds are 

especially vulnerable to these disruptions. 

The 

down drift 

side of 

the groin 

loses sand 

because of 

continuing 

longshore 

movement. 
C 0 A S T S I N C R I S I S 17 

Sand dunes help absorb the pounding of 

high waves and reduce overwash flooding 

during storms; bulldozing dunes to improve 

views of the sea destroys this natural protection. Dredging navigation channels and 

tidal inlets and discharging the material in 

deep water also remove sediment from the 

coastal system and interfere with longshore 

transport. Canals cut in wetlands for navigation, pipelines, and drainage provide 

channels for salt-water invasion during storms 

and high tides; the increased salinity often 

kills marsh plants, leading to accelerated land 

loss and deterioration of wetlands. 

WATER-LEVEL CHANGES 

Human activities can cause local and 

possibly global changes in sea level. Pumping 

of ground water, salt brines, and petroleum 

resources from coastal environments has led 

to significant subsidence in many regions; 

the Texas coast around Galveston Bay has 

experienced a particularly alarming rise in its 

relative sea level. The increasing release of 

greenhouse gases, such as carbon dioxide and 

methane from automobile and industrial 

exhaust, may promote global warming, the 

melting of massive ice sheets in Greenland 

and Antarctica, and consequently the raising 

of sea level worldwide. 

Fragile wetlands are easily damaged by salt water 

that invades canals dredged for navigation and oil 

exploration. 

Vehicle tracks cut across the sand dune, destroying 

plants and leaving it vulnerable to erosion. 
18 C 0 A S T S I N C R I S I S 

COASTAL CONFLICTS 

Conflicts between human activities and 

natural systems exist wherever the two come 

together in the coastal environment; indeed, 

some clashes are inevitable. However, increasing demands on our coastal environments as a 

result of the competition between human goals 

and natural processes have led to dramatic 

examples of these conflicts. Among the most 

striking examples are Ocean City, Maryland; 

Hurricane Hugo's effects on Puerto Rico and 

South Carolina; Isles Dernieres, Louisiana; 

and Boston Harbor, Massachusetts. 

OCEAN CITYAn Urbanized Barrier Island 

Ocean City, Maryland, has been a popular 

beach resort for more than a century. During 

the 1920's, several large hotels and a boardwalk 

were built to accommodate visitors. Development was slow but steady until the early 1950's, 

when a dramatic boom in construction began 

that lasted almost 30 years. Early concerns 

about the coastal environment were raised in 

the late 1970's and led to Federal and State 

laws to limit dredging and filling of wetlands. 

The resort is built on the southern end of 

Fenwick Island, one of the chain of barner 

islands stretching from New York to Florida. 

Ocean City Inlet, which connects the quiet 

backwater bay with the Atlantic Ocean at the 

southern end of the island, was opened during 

the great hurricane of 1933, by storm-surge 

overwash from the bay side. To maintain the 

inlet as a navigation channel, two stone jetties 

were constructed by the U.S. Army Corps of 

Engineers shortly after the storm. The jetties 

have stabilized the inlet, but they have drastically altered the sand-transport processes 

near the inlet. The net longshore drift at Ocean 

City is southerly; it has produced a wide beach 

at Ocean City north of the jetty, but Assateague 

Island, south of the inlet, has been starved of 

sediment. The result is a westerly offset of 

more than 500 meters in the once-straight 

barrier island. 

Oblique view of the highly developed barrier beach at Ocean City. The dunes that once protected the island 

have been removed to improve the view, and the tall apartment buildings are so close to the water's edge that 

the beach is shadowed by midafternoon. Many of these buildings were damaged by flooding immediately after 

their construction. Beach replenishment along Fenwick Island in 7988 and 7990 by the State of Maryland and 

the U.S. Army Corps of Engineers is designed to provide some temporary protection to the buildings and to 

increase the recreational value of the beach. 
C 0 A S T S I N C R I S I S 19 

The most damaging storm to hit Ocean City 

within historic times was the Five-High or Ash 

Wednesday northeaster of early March 1962. It 

caused severe erosion and flooding along much 

of the middle Atlantic Coast. For 2 days, over 

five high-tide cycles, all of Fenwick Island 

except the highest dune areas was repeatedly 

washed over by storm waves superimposed on 

the 2-meter-high storm surge. Property damage 

to Ocean City alone was estimated at $7.5 

million. Given the dense development of the 

island over the last 20 years, damage from a 

similar storm would today be hundreds of 

millions of dollars. 

Above: The dashed line on this 1978 photograph 

marks the approximate limit of the storm surge 

during the Five-High storm of March 1962. Most of 

the large buildings within the storm-surge zone were 

constructed during the 1970's; capital expenditures 

for these buildings and the large number of mobilehome parks that are also within the surge zone were 

more than $100 million. Their value today is several 

billion dollars. (From Dolan and others, 1980.) 

Right: Shoreline changes in the Fenwick lslandAssateague Island region between 1849 and 1980 

show the dramatic effects of the two large jetties at 

Ocean City Inlet on the natural sediment-transport 

processes along the coast. 

Oblique view of Ocean City Inlet (about 1980) showing the 500-meter offset between Fenwick Island (north) and Assateague Island (south) due to 

sediment starvation as a result of construction of the jetties in the 1930's. 

38"17 

Upper Sinepuxent 

Neck 

-- 1980 

.............. 1849 

ATLANTIC 

OCEAN 

N 

A 

1 2M1LES 

II I I 

2 KILOMETERS 
20 C 0 A S T S I N C R I S I S 

Hurricane Hugo caused at least $2.5 billion in damages to Puerto Rico. 

HURRICANE HUGOStorm Devastation 

Hurricane Hugo struck Puerto Rico in midSeptember 1989, packing wind speeds of more 

than 250 kilometers per hour at the height of 

the storm. The 0.6-meter storm surge, combined with the rising tide and the 3- to 5-meter 

storm waves, inflicted serious damage to the 

island and its economy; total monetary damage 

was $2.5 billion, and eight people died during 

the hurricane and its aftermath. The position 

of the sh oreline remained generally constant, 

but much sand was removed from the beach 

and deposited behind the dunes, outside of 

the coastal environment. Coral colonies were 

choked by sediment, and many were destroyed. A large offshore sand deposit (about 

90,000,000 cubic meters) was leveled by storm 

waves and dispersed over the ocean floor. 

Hugo hit the U.S. mainland just north of 

Charleston , South Carolina, bringing sustained 

winds of 215 kilometers per hour and a maximum storm surge of more than 6 meters. The 

barrier islands along the South Carolina coast 

are generally less than 3 meters above sea 

level, and many showed evidence of having 

been completely inu ndated by the storm surge . 

In many places, beaches were severely eroded 

and dunes w e re leveled. Much of the sand 

removed from the beach was overwashed 

landward or carried offshore . A total of 29 

people in South Carolina died, and total damages were $5 .9 billion. 

The damage Hugo caused along South 

Carolina's barrier islands and shore commu -

nities clearly shows the importance of good 

construction and the natural protection 

provided by a wide, high beach and sand 

dunes. Folly Beach, south of Charleston, was 

on the weaker (south) side of th e hurricane, 

but its beaches were already severely 

narrowed by long-term erosion; homeowners 

had dumped boulders and concrete rubble on 

the beach to form a protecting revetment. 

The revetment proved useless during Hugo. 

The storm surge (over 3.5 meters at Folly 

Beach) overtopped the structure, caused major 

damage to beachfront houses, and totally 

swept away a popular seafood restaurant. 

Isle of Palms and Sullivans Islan d , north of 

Charleston, suffered substantial damage, but 

the effects were somewhat lessened by a wide 

beach and dunes. Houses that survived were 

built to withstand high winds and floodin g, in 

contrast to homes built to lower standards that 

were totally destroyed. 
C 0 A S T S I N C R I S I S 21 

Damage by Hugo to South Carolina's Isle of Palms and Sullivans Island underscores the need for knowledge of 

beach and storm processes in order to protect lives and property. 
22 C 0 A S T S I N C R I S I S 

ISLES DERNIERESEroding Barrier Islands 

The Isles Dernieres barrier chain stretches 

for 32 kilometers along the coast of Louisiana, 

about 100 kilometers west of the mouth of the 

Mississippi River and 120 kilometers southwest 

of New Orleans. Coastal studies conducted 

since 1985 by the USGS and the Louisiana 

Geological Survey indicate that the Isles 

Dernieres are eroding as fast as 20 meters 

per year. These high erosion rates, caused by 

both natural forces and human actions, have 

produced one of the most rapidly deteriorating 

shorelines in the world. 

Geologic investigations during the last 40 

years have shown that the low-lying plain and 

coastal barrier islands of southern Louisiana 

consist of fine sand and mud deposited by the 

Mississippi River in four successive delta 

complexes over the past 7,000 years. Each 

time the river channel moved to a new position, 

the combination of natural subsidence and 

reduction in sediment supply caused erosion 

and deterioration of the abandoned delta. 

The Isles Dernieres mark the end of a delta that 

reached its maximum size about 500 years ago. 

By the mid-1800's, the Isles Dernieres were 

a single wide barrier island supporting mature 

forests and a thriving resort community. A devastating hurricane struck the island in 1856, 

destroying the resort and killing hundreds of 

people. Over the past 130 years, natural processes of storm erosion and a rise of more than 

a meter in relative sea level have dramatically 

reshaped the Isles Dernieres. The once-continuous island has been cut by wide tidal inlets into 

five smaller islands, which have shrunk rapidly 

in recent years. They are now so close to sea 

level that they are overwashed during storms 

and high tides six to eight times a year. Extrapolation of the historic data shows that if these 

erosion rates continue the Isles Dernieres will 

be submerged by approximately the year 2020. 

Although the disappearance of these islands 

will not have an immediately noticeable impact, 

as would the destruction of a developed barrier 

like Ocean City, Maryland, it will expose the 

wetlands and estuaries of southern Louisiana to 

greater wave and current action and may hasten 

the loss of these vital resources. 

The Isles Dernieres have one of the most rapidly eroding shorelines in the world; they are overwashed by storms 

and high tides half a dozen times a year. 
Caillou Bay 

COASTS IN CRISIS 23 

Terrebonne 

Bay 

~ 

~ 

Vine 

Island 

Isle Derniere GULF OF MEXICO 

1853 

Caillou Bay 

~ 

~ 

Terrebonne 

Bay 

~ Lake Pelto ~ 

Isles Demieres 

~~ ~ N 

GULF OF MEXICO A 

1978 

0 5 MILES 

0 5 KILOMETERS 

In the past 150 years, rapid erosion of the protecting barrier islands has exposed Louisiana's valuable wetlands 

and estuaries to increased storm waves and currents. (Modified from Penland and others, 1989.) 
24 C 0 A S T S I N C R I S I S 

The protecting islands that enclose Boston Harbor also block ocean currents, which would otherwise help 

disperse urban pollutioa. 
C 0 A S T S I N C R I S I S 25 

BOSTON HARBORCenturies of Pollution 

Boston, one of the oldest and largest metropolitan centers in the United States, covers 

about 1,500 square kilometers and includes 

more than 75 separate cities and towns. One 

of the earliest metropolitan boards to unite 

these separate entities was the Metropolitan 

Sewerage Board, established in 1889 to deal 

with the growing pollution of Boston's rivers 

by raw sewage. A century later, Boston Harbor 

and the surrounding beaches are still plagued 

by pollution. In addition to the continued 

sewage problem, heavy metals (chromium, 

copper, lead, and zinc, for example) also 

contaminate the sediments in the harbor, as 

well as the fish and shellfish that are a major 

source of revenue. These contaminated 

sediments may continue to be sources of toxins 

long after the primary pollution sources are 

reduced or eliminated. 

A $6 billion cleanup plan, to be completed by 

the year 2000, includes elimination of ocean discharge of sewage sludge, upgrades of sewage 

treatment, and construction of a new ocean outfall for the treated effluent about 13 kilometers 

seaward of the harbor mouth. As part of the 

effort and in cooperation with the Massachusetts 

Water Resources Authority, the USGS has 

established a long-term current and sedimenttransport monitoring station in Massachusetts 

Bay to provide information vital to the design of 

the proposed ocean outfall. Additional USGS 

studies, coordinated with other Federal and State 

agencies through the Massachusetts Bay Management Committee, are mapping the sediment 

composition on the bay floor, determining the 

levels of various contaminants in the sediments, 

and estimating rates of sediment accumulation 

and mixing. Data and interpretations gained 

though these studies are helping to determine 

the fate and effects of pollutants and will assist 

coastal managers to develop efficient cleanup 

procedures and mitigation measures. 

Boston has been an important harbor for centuries; this engraving shows its lighthouse in 7 789. (From the 

Massachusetts Magazine, 7 789). 
26 C 0 A S T S I N C R I S I S 

SOURCES 

river discharge 

shoreline erosion 

offshore deposits 

DESTINATIONS 

shoreline accretion 

storm was hover 

tidal inlets 

temperature 

transpiration 

precipitation 

evaporation 

waves 

coastal structures h-.;~~;:..:=.~.,.....,r-lr------l\-+- >-"'--/''-"'--"-"-"--"--"--''-'~ 

longshore currents 

river discharge 

building or cutting 

of valleys 

tides 

winds 

storms 

offshore deposits 

resource extraction 

river basin development 

maintenance dredging 

beach maintenance 

coastal structures 

artificial inlets 

dune alterations 

highway construction 

RELATIVE 

SEA LEVEL 

tectonic subsidence 

compactional subsidence 

global sea-level change 

local sea-level change 

Factors affecting coastal environments are interwoven in an intricate web. (Modified from 

Pi/key and others, 1989, Coastal/and loss; 28th International Geological Congress Short 

Course: Washington, D.C., American Geophysical Union, 73 p.) 

CONCLUSIONSEarth-Science Challenges and Opportunities 

Coasts, as boundaries between land and 

water, are characterized by the geologic nature 

of the land, which is unstable and often fragile, 

and the dynamic power of wind and sea. As a 

result, coastal environments are constantly 

changing as they seek to achieve arid maintain 

equilibrium among the many opposing natural 

forces. The vibrant beauty of shore areas is 

attracting a growing population of homeowners 

and vacationers; however, the ever-changing 

character of coasts makes them hazardous for 

people and, in the long term, for buildings and 

structures. The risks associated with living 

along a coast are comparable to those 

experienced by people living on a river flood 

plain, near an earthquake fault, or close to a 

volcano-all carry the possibility of eventual 

catastrophe. Because coastal regions have 

wide public appeal as places to live, population 

growth continues to accelerate along our 

Nation's coastline. This population explosion 

superimposed on the dynamic forces acting on 

coasts is leading to a coastal crisis marked by 

the following concerns: 

• Coastal erosion at widely varying rates affects 

all 30 coastal States and all of the U.S. Island 

Territories. 

• During the past 200 years, more than half of 

our valuable wetlands have been lost due to a 

combination of natural processes and human 

intervention. 

• Pollution of coastal areas has forced the closing 

of one-third of the Nation's shellfish beds, has 

restricted beach use, and has permanently contaminated ground water in some communities. 

• In many coastal urban areas, hard-mineral 

resources such as sand and gravel for construction and beach nourishment are no 

longer available onshore. Offshore deposits 

may provide an alternative but pose environmental and economic dilemmas. 

The crisis in the coastal zone is worldwide 

but is especially alarming in the United States, 

where an expanding and more affluent popula-
C 0 A S T S I N C R I S I S 27 

tion combined with a variety of government 

subsidies over the past 50 years have enabled 

widespread and often unwise development to 

take place. If present demographic trends of 

population growth and expanded development 

continue, and if sea-level rise brought on by potential climate changes also occurs, stress on our 

coastal environments will increase substantially. 

Intelligent stewardship of our coastal resources requires balancing human needs and 

expectations with coastal realities. Earthscience information that is based on sound 

scientific research on our coasts, the way they 

change, and the factors influencing their development is critical in any attempt to lessen the 

conflicts and ease the tensions brought on by 

competing human goals and natural processes. 

Ignorance and continued disregard of the 

geologic processes that constantly reshape our 

coasts are tragically intensifying the collisions 

between people and nature. Despite historical 

precedents, catastrophes like Hurricane Hugo 

catch us unaware and unprepared. As powerful as Hugo was, it will be surpassed by bigger 

RESEARCH QUESTIONS ON 

COASTAL PROCESSES 

How do the prevailing winds, waves, 

tides, and seasonal weather patterns 

affect coastal environments? 

What are the sediment sources, sediment volumes, and rates of sediment 

movement into, out of, and within 

coastal areas? 

What biologic communities inhabit 

specific coasts? How do they affect 

(and how are they affected by) 

sediment movement? 

What short-term and long-term 

factors and processes control the 

movement of sediment and changes 

to the coastal sediment budget? 

RESEARCH QUESTIONS ON 

SHORT-TERM COASTAL EVENTS 

How often do major storms strike 

specific sections of the coastline? 

What are the geologic effects of 

these storms-extent of flooding, 

height of storm surge, sediment 

mixing in estuaries and bays? 

What are the effects on coastal 

sediments-erosion, deposition, 

changes in the sediment budget? 

Can these movements of water and 

sediment be quantitatively predicted 

for storms of specific strength and 

duration? 

Which effects of storms are permanent and which are temporary? 

storms in the future; population growth and 

increased development along the coasts suggest 

that these future storms may cause even more 

damage and loss of life. Hugo is providing a 

regional incentive to increase our understanding of coastal environments and processes, 

and it is forcing an examination of laws and 

insurance regulations that govern societal 

actions within coastal zones. 

Coordinated multidisciplinary efforts are 

needed to improve our understanding of how 

coasts form and evolve. A clear understanding 

of how coastal environments have formed and 

what natural changes they have undergone 

in the recent geologic past can be critical in 

predicting with confidence their future. Many 

different scientific disciplines must be involved. 

Many different scientific groups can provide 

critical expertise in specific fields of research. 

Cooperation among Federal, State, and local 

agencies will ensure that this scientific expertise 

is applied in site-specific studies to solve the 

individual problems that make up the coastal 

crisis. Concerted efforts focused on under-
28 C 0 A S T S I N C R I S I S 

standing our coasts require efficient coordination to get maximum return from the limited 

resources available. 

As important as increasing our basic scientific understanding of the earth-science processes affecting coasts is, it is equally important to make this information available to 

coastal-zone planners, managers, and engineers in forms that they understand and can use. 

These groups must have adequate, accurate 

information on coastal processes in order to 

make decisions, assess risks, and solve problems in an efficient and cost-effective manner. 

Some engineering practices and human 

activities that are incompatible with natural 

processes and that cause long-term harm to 

RESEARCH QUESTIONS ON 

LONG-TERM CHANGES 

IN WATER LEVELS 

Can paleoclimate studies help us to 

predict future global climate change? 

How has global sea level changed 

throughout geologic and historic 

times? What factors have determined these changes? 

For specific sections of the coast, are 

changes in relative water level significant on a local or regional scale? 

What effects will future changes in 

water level, global and local, have on 

coasts and development in the 

coastal zone? 

What is the current rate of worldwide sea-level change? Can we 

predict future changes with 

confidence? 

Are lake-level changes cyclic, and 

can we predict their magnitudes, 

frequency, and duration? 

RESEARCH QUESTIONS ON 

HUMAN INVOLVEMENT 

ALONG COASTS 

What are the qualities and quantities of construction materials {sand, 

gravel. and shell). metals {gold, 

titanium, and so on). and potable 

water resources? 

What effects do groins, jetties, 

breakwaters, seawalls, revetments, 

levees, and other engineering 

structures have on coastal 

processes? 

Can mitigation techniques, such as 

the mechanical transport of 

sediment trapped by jetties at tidal 

inlets, be designed to reduce 

downdrift erosion caused by 

engineering structures? 

How are buildings, roads, bridges, 

pipelines, and other infrastructure 

affected by coastal processes? 

What long-term effects does the 

damming of rivers have on the 

sediment budget of coastal areas? 

What effects does the withdrawal of 

underground fluids and minerals 

have on sediment compaction and 

local subsidence? 

How are contaminated sediments 

and pollutants dispersed in the 

coastal zone? What is their ultimate disposition in the coastal 

environment? 

How are ground-water resources 

affected by dredging of navigation 

channels, mining of minerals, and 

waste disposal in the coastal zone? 
C 0 A S T S I N C R I S I S 29 

The aftermath of a storm in the South Pacific. 

the coast can be modified to lessen their effect. 

In other cases, erosion mitigation techniques 

that closely replicate natural processes, such 

as beach nourishment, sand dune creation, 

and shoreline restoration, can be used to 

provide temporary protection. In extreme 

circumstances, abandonment and relocation 

of communities might be the best alternative. 

Dealing effectively with the present coastal 

crisis and resolving future conflicts along our 

coasts will require a combination of solutions 

that must be based on long-term societal 

needs and on sound scientific and technical 

knowledge, rather than emotional responses 

to short-term desires. Results of scientific 

investigations must be clearly communicated 

to coastal planners, engine ers, and managersand, most important, to political decisionmakers and the public. Only when these 

diverse groups understand the range of 

choices, and the costs (social, financial, and 

environmental) and risks associated with each 

choice, can prudent and enlightened decisions 

be made. 

Research and field investigations by the 

U.S. Geological Survey and other groups over 

the past few decades have enhanced our 

understanding of the processes affecting the 

coasts, but many uncertainties remain. The 

earth-science community-the USGS and 

other Federal and State agencies, departments of academic institutions, and private 

research organizations-is beginning to address many complex and fascinating scientific 

aspects of coastal evolution. Through focused 

and concerted efforts, earth scientists will be 

able to provide decisionmakers and the public 

with the information and interpretations they 

need in order to plan wisely for the future 

of our coasts. 
30 C 0 A S T S I N C R I S I S 

FURTHER READING 

COASTAL WETLANDS 

Chabreck, R.A., 1988, Coastal marshes; ecology and wildlife management: Minneapolis, Minn., University of 

Minnesota Press, 138 p . 

Part of a series on wildlife habitats; this volume describes the coastal marshes of the United States 

with particular emphasis on the northern Gulf of Mexico coastline. Environmental influences, plant 

and animal communities, and the reasons for alteration and loss of marshes are clearly explained for 

the nontechnical reader; sections on marsh management and the future of marshes give the author's 

suggestions for minimizing damage to this ecologically valuable environment. 

Crisis on Louisiana's coast...America's loss, published by U.S. Army Corps of Engineers, New Orleans District, in 

cooperation with the State of Louisiana, 12 p. 

Explains the economic and ecological importance of Louisiana's wetlands, the causes of their loss, 

and the steps being taken by the State and six Federal agencies to address this critical problem, in an 

easy-to-read style. 

BARRIER ISLANDS 

Dolan, Robert, Lins, Harry, and Stewart, John, 1980, Geographical analysis of Fenwick Island, Maryland, a 

middle Atlantic coast barrier island: U.S. Geological Survey Professional Paper 1177-A. 24 p . 

Dolan, Robert, and Lins, Harry, 1986, The Outer Banks of North Carolina: U.S. Geological Survey Professional 

Paper 1177- B, 4 7 p. 

Highly urbanized Fenwick Island and the less developed islands of North Carolina are analyzed to 

demonstrate the processes and hazards associated with coastal barrier islands. The intended 

audience includes land-use planners, managers, and developers. 

Leatherman, S.P., 1988, Barrier island handbook: College Park, Md., University of Maryland Coastal 

Publications Series, 92 p. 

A thorough, nontechnical explanation of barrier island environments, their evolution, and the impact 

of recreation and construction on them. 

SEA-LEVEL CHANGE AND COASTAL EROSION 

Committee on Coastal Erosion Zone Management, 1990, Managing coastal erosion: Washington, D.C., National 

Academy Press, 182 p . 

This report was commissioned by the Federal Emergency Management Agency's Federal Insurance 

Administration to provide options for implementation of a coastal erosion zone management 

program; it also explores some of the major questions about developing a national policy on coastal 

erosion. 

Committee on Engineering Implications of Changes in Relative Mean Sea Level, 1987, Responding to changes in 

sea level- Engineering implications: Washington, D.C., National Academy Press, 148 p. 

The first half of this book examines the history and estimated future (over the next century) of sea 

level, including the effects of sea-level rise on the coastal zone; the second half gives general and 

specific engineering responses to sea-level rise. The committee concludes that, in most areas, 

acceleration in the rate of mean sea-level rise is likely enough that it will affect planning and design 

of coastal facilities. It recommends increases in the funding of research on coastal processes, to 

provide adequate scientific knowledge to support decisions about protecting or abandoning coastal 

facilities as sea level rises. 

Committee on Options for Preserving Cape Hatteras Lighthouse, 1988, Saving Cape Hatteras lighthouse from 

the sea- Options and policy implications: Washington, D.C., National Academy Press, 135 p . 

The Cape Hatteras lighthouse, the tallest brick lighthouse in the United States, is a symbol of the 

erosion problem on the southern Atlantic Coast. This report, commissioned by the National Park 

Service, documents the options the Park Service has to preserve the lighthouse and recommends that 

it be relocated rather than protected in place. The choices discussed also apply to many other 

National Parks, where historic buildings are subject to destruction by erosion. 
Penland, Shea, Ramsey, K.E., McBride, R.A., Maslow, T.F., and Westphal, K.A., 1989, Relative sea level rise and 

subsidence in Louisiana and the Gulf of Mexico: Baton Rouge, La., Louisiana Geological Survey Coastal 

Geology Technical Report No.3, 65 p. 

Documents the rates of land loss in Louisiana and the northern Gulf of Mexico through the combined 

action of subsidence due to compaction and sea-level rise. Highest rates were found for the 

Mississippi River Delta plain; the authors extrapolate a relative sea-level rise of 1.5-2 meters over the 

next century. 

BEACH AND WAVE MECHANICS 

Bascom, Willard, 1980, Waves and beaches; the dynamics of the ocean surface (revised and updated): Garden 

City, N.Y., Anchor Press/Doubleday, 366 p. 

A highly readable book that describes the theory of wave action and the considerable effects that 

waves can have on beaches, ships, and other engineered structures. 

King, C.A.M., 1972, Beaches and coasts (2d ed.): New York, St. Martin's Press, 570 p. 

Examines different types of beaches and coasts and the wave and wind processes that shape them. 

Many of the examples are from Great Britain. 

SHORE DEVELOPMENT 

Culliton, T.J., Warren, M.A., Goodspeed, T.R., Remer, D.G., Blackwell, C.M., and McDonough, J.J., III, 1990, 50 

years of population change along the Nation's coasts, 1960-2010: Rockville, Md., National Oceanic and 

Atmospheric Administration Coastal Trends Series, 2d report, 41 p. 

Provides information on current and future population trends along the Nation's coastlines, which are 

grouped into five major regions: Northeast, Southeast, Great Lakes, Gulf of Mexico, and Pacific. 

Size, distribution, and density projections are given for regions, States, and counties. 

Kaufman, Wallace, and Pilkey, O.H., Jr., 1983, The beaches are moving; the drowning of America's shoreline 

(with a new epilogue): Durham, N.C., Duke University Press, 336 p. 

Originally published in 1979 and reprinted with a new epilogue in 1983 to accompany the series 

"Living with the Shore" (see below). The authors hold strong views against building structures near 

the coastline; this nontechnical book explains the natural coastal processes that form and change 

beaches and describes some of the problems that arise when we attempt to control these natural 

processes. 

Morrison, H.R., and Lee, C.E., 1981, America's Atlantic Isles: Washington, D.C., National Geographic Society, 

200 p. 

Beautiful photographs and readable text describe the wide variety of islands found along the U.S. 

Atlantic shoreline from Maine to Florida, as well as the range of wildlife and human communities 

that inhabit this region. 

Pilkey, O.H., and Neal, W.J., series editors, Living with the shore: Durham, N.C., Duke University Press. 

This series currently contains 14 volumes, each of which examines the shoreline of an individual 

State (Florida has two volumes, for East and West Florida). The books are intended for a nontechnical audience; they review the geologic history, the history of development, the coastal processes 

affecting the shoreline, human intervention on the shore, government programs affecting coastal 

real estate, and safeguards to take when buying or building to prepare for storms and hurricanes. 

The books also contain a detailed analysis of the entire shoreline with recommendations of where 

and where not to buy shore property. 

Yassa, W.E., and Hartman, E.M., Jr., 1976, Beach forms and coastal processes: MESA New York Bight Atlas 

Monograph 11, 50 p. 

Presents findings on natural and manmade beaches, dunes, shoreline structures, beach growth and 

erosion, and storm effects along the New York Bight, the part of the Atlantic coastline from Long 

Island to New Jersey. This paper is one of a series of technical monographs providing decision 

makers with information on the complex coastal processes of the Bight and the human impact on 

these processes. The series was a cooperative effort between the National Oceanic and Atmospheric 

Administration and the New York State Sea Grant Institute. 
Federal Agencies With Regulatory or 

Research Responsibilities for Our Coasts 

Federal Emergency Management Agency (independent Federal organization) administers the 

National Flood Insurance Program (NFIP), which provides Federally subsidized insurance protection 

in many coastal and flood-prone areas of the United States. Making NFIP self-supporting and eliminating Federal subsidies are major goals. 

National Oceanic and Atmospheric Administration (U.S. Department of Commerce) conducts studies 

of wetlands and coastal habitats that support marine resources; prepares nautical charts and geodetic 

surveys of coastal areas; monitors storm activities; operates an environmental satellite system; 

administers a grants program for marine research. 

National Park Service (U.S. Department of the Interior) administers an extensive system of public 

lands, including lakeshores and seashores, set aside for the protection of natural environments, the 

preservation of historic properties, and the education and enjoyment of our citizens. 

National Science Foundation (independent Federal organization) supports fundamental, long-term 

coastal research in the earth sciences and in engineering fields. This support is made through grants, 

contracts, and agreements awarded to universities and other research groups. 

U.S. Army Corps of Engineers (U.S. Department of Defense) conducts applied research and 

development for design, construction, operation, and maintenance activities related to harbors, 

navigational waterways, and coastal protection. The Corps also administers laws for protecting 

navigable waters and related coastal resources such as wetlands. 

U.S. Coast Guard (U.S. Department of Transportation) is responsible for enforcing laws related to the 

protection of marine environments; provides a national response center that investigates oil and 

chemical spills, initiates penalty actions, and monitors and coordinates cleanups. 

U.S. Environmental Protection Agency (independent Federal agency) funds and conducts contaminant studies and related coastal research; regulates the discharge of coastal pollutants and the 

disposal of dredged sediments. 

U.S. Fish and Wildlife Service (U.S. Department of the Interior) manages extensive coastal lands as 

wildlife preserves; conducts research on coastal wetlands, fish and wildlife populations, and changes 

in habitat. 

U.S. Geological Survey (U.S. Department of the Interior) conducts research on the geologic 

framework of coasts and on sediment-transport processes; collects and analyzes hydrologic data; 

makes topographic, geologic, and hydrologic maps of coastal areas; investigates ancient and modern 

coastal environments. 

U.S. Minerals Management Service (U.S. Department of the Interior) studies the potential impact of 

offshore activities, including the placement and construction of petroleum pipelines, on coastal 

wetlands and resources; funds research through State geoscience agencies for identifying mineral 

resources in the coastal zone. 

U.S. Soil Conservation Service (U.S. Department of Agriculture) carries out detailed soil surveys for 

coastal and wetland regions; identifies superior plant varieties for erosion control in coastal zones. 
Back cover: High water levels in Lake Michigan created an unusual hazard 

for Chicago motorists in the mid-1980's. 
DANGEROUS WAVES 

- PARK AT YOUR RISK 

No fREE cnnows 

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