Shoreline movements Report 1 : Cape Henry, Virginia, to Cape Hatteras, North Carolina, 1849-1980

[From the U.S. Government Printing Office, www.gpo.gov]

TECHNICAL REPORT CERC-83-1

SHORELINE MOVEMENTS
US Army Corps
of Engineers Report 1
CAPE HENRY, VIRGINIA, TO
CAPE HATTERAS, NORTH CAROLINA, 1849-1960

by
Craig H. Everts
National Oceanic Coastal Engineering Research Center
and Atmospheric U. S. Arm Engineer Waterways Experiment Station
Administration y
P. 0. Box 631, Vicksburg, Miss. 39180

and
Jeter P. Battley, Jr., and Peter N. Gibson
National Ocean Service
National Oceanic and Atmospheric Administration
U. S. Department of Commerce
6001 Executive Blvd., Rockville, Md. 20852

July 1983
Report 1 of a Series

Approved For Public Release; Distribution Unlimited

GB
495.4
.E9_3
1983 Prepared for Office, Chief of Engineers, U. S. Army
Washington, D. C. 20314
and National Oceanic and Atmospheric Administration
Rockville, Md. 20852

Destroy this report when no longer needed. Do not return
it to the originator.

The findings in this report are not to be construed as an official
Department of the Army position unless so designated.
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Citation of trade names does not constitute an
official endorsement or approval of the use of
such commercial products.

Unclassified
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REPORT DOCUMENTATION PAGE BEFORE COMPLETING FORM
1. REPORT NUMBER GOVT ACCESSION NO. 3. RECIPIENT'S CATALOG NUMBER
Technical Report CERC-83-1

4. TITLE (and Subtitle) 5. TYPE OF REPORT & PERIOD COVERED
SHORELINE MOVEMENTS; Report 1: CAPE HENRY, Report I of a series
VIRGINIA, TO CAPE HATTERAS, NORTH CAROLINA,
1849-1980 6. PERFORMING ORG. REPORT NUMBER

7. AUTHOR(a) S. CONTRACTOR GRANT NUMBER(.)
Craig H. Everts
Jeter P. Battley, Jr.
Peter N. Gibson
9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT, PROJECT, TASK
U. S. Army Engineer Waterways Experiment Station AREA & WORK UNIT NUMBERS
Coastal Engineering Research Center
P. 0. Box 631, Vicksburg, Miss. 39180 and
U. S. Department of Commerce 12. REPORT DATE
National Oceanic and Atmospheric Administration July 1983
National Ocean Service 13. NUMBER OF PAGES
6001 Executive Blvd., Rockville, Md. 20852 113
11 CONTROLLING OFFICE NAME AND ADDRESS IS. SECURITY CLASS. (.1 this rePort)
bffice, Chief of Engineers, U. S. Army Unclassified
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16. DISTRIBUTION STATEMENT (of this Report)
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Property of CSC Library

18. SUPPLEMENTARY NOTES
Available from National Technical Information Service, 5285 Port Royal Road,
Springfield, Va. 22161.
U - S - DEPARTMENT OF COMMERCI NOA
19. KEY WORDS (Continue on reverse aids It necessary and Identify by block numbel@;UASTAL SERVICES CENTER
Atlantic coast 2234 SOUTH HOBSON AVENUE
Beach erosion CHARLESTON, SC 29405-241-
Coastal morphology
Shorelines

20, A8ST-RACr(CAvth@ aware"ra* &fib ffnecvraary aad identify by block nuambat)
Shoreline position changes between about 1850 and 1980 along the ocean
coastal reach from 12 km west of Cape Henry, Virginia, to 8 km west of Cape
Hatterasi North Carolina, are documented in this report. In places where the
ocean shoreline is on an island or spit, shoreline changes in the sound or bay
are also given. Shoreline movement maps at a scale of 1:24,000 constitute the
basic data set included in the report. Composite reproductions of these maps
are shrinkwrapped separately. In addition, ocean and sound shoreline changes
(Continued)
C-@
LA DD FORM 14n EDITION OF I NOV 6S, IS OBSOLETE.
JAN 73

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20. ABSTRACT (Continued).

averaged for 1-minute-latitude- (or longitude-) distance increments are pro-
vided.
Consistent alongshore trends in the shoreline change rate are evident
only from Virginia Beach south to the Virginia-North Carolina border and for
about 15 km north of Cape Hatteras. Other areas experienced variable rates of
shoreline change. The highest average shoreline change rate, about -2.0 m/year,
occurred between 1917 and 1949. From about 1850 to 1917, the shoreline change
rate averaged -0.1 m/year, and for the past 30 years it has averaged about
-0.9 m/year.

Unclassified
SECURITY CLASSIFICATION OF THIS PAGE(Whon Dot. Entered)

PREFACE

This report is the result of a cooperative effort of the National Ocean
Service (NOS), National Oceanic and Atmospheric Administration, 'U. S. Depart-
ment of Commerce, and the Coastal Engineering Research Center (CERC) of the
U. S. Army Engineer Waterways Experiment Station (WES). The study, based on a
comparison of historic survey data contained in the archives of NOS, was
funded jointly by the Office, Chief of Engineers, and the National Oceanic and
Atmospheric Administration. All survey data reduction and quality control
were performed by NOS; data analyses and report preparation were accomplished
primarily by CERC.
The report was prepared by Dr. Craig H. Everts, CERC, and
Messrs. Jeter P. Battley, Jr., and Peter N. Gibson, NOS. The work was car-
ried out under the general supervision of Mr. N. E. Parker, Chief, Engineer-
ing Development Division, CERC; Mr. R. P. Savage, Chief, Research Division,
CERC; and Dr. R. W. Whalin, Chief, CERC. At CERC, Mr. Edward Hands developed
a computer program to analyze shoreline change data and Mr. Jon Berg reduced
the data. The section on historic inlets was researched by Ms. Marie Ferland,
CERC. Reviewers included Drs. Robert Byrne and Robert Dolan and
Messrs. William Birkmeier, Edward Hands, Thomas Jarrett, James Melchor,
Neill Parker, and S. Jeffress Williams.
Commander and Director of WES during the publication of this report was
COL Tilford C. Creel, CE. Technical Director was Mr. F. R. Brown.

CONTENTS

Page
PREFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I

LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

LIST OF FIGURES . . . . . ... . . . . . . . . . . . . . . . . . . . . . 4

CONVERSION FACTORS, INCH-POUND TO METRIC (SI)
UNITS OF MEASUREMENT . . . . . . . . . . . . . . . . . . . . . . . . . 8

PART I: INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . 9

PART II: STUDY AREA . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Geographical Setting . . . . . . . . . . . . . . . . . . . . . . 12
Historic Inlets . . . . . . . . . . . . . . . . . . . . . . . . . 16
Inlet location . . . . . . . . . . . . . . . . . . . . ;. . 16
Accuracy of inlet location . . . . . . . . . . . . . . . . . 25
Continental Shelf . . . . . . . . . . . . . . . . . . . . . . . . 26
Tides, Winds, and Waves . . . . . . . . . . . . . . . . . . . . . 29
Tides and other sea level fluctuations . . . . . . . . . . . 29
Wind conditions . . . . . . . . . . . . . . . . . . . . . . 32
Waves . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Coastal Storms . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Coastal Structures . . . . . . . . . . . . . . . . . . . . . . . 38

PART III: DATA REDUCTION . . . . . . . . . . . . . . . . . . . . . . . 44

Data Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Shoreline Definition . . . . . . . . . . . . . . . . . . . . . . . 44
Methods Used to Revise the 1980 Mean High Water Line . . . . . . 50
Data Reduction Procedures . . . . . . . . . . . . . . . . . . . . 51
Quality Control and Potential Errors . . . . . . . . . . . . . . 52
PART IV: DATA ANALYSIS AND DISCUSSION . . . . . . . . . . . . . . . . 55
Analysis Methodology . . . . . . . . . . . . . . . . . . . . . . . 55
Shoreline Change Rates . . . . . . . . . . . . . . . . . . . . . 58
Listing of shoreline change rates . . . . . . . . . . . . . 58
Ocean shoreline change rates . . . . . . . . . . . . . . . . 62
Sound shoreline change rates . . . . . . . . . . . . . . . . 71
Oregon Inlet . . . . . . . . . . . . . . . . . . . . ... . . 71
Cape Hatteras and Cape Henry . . . . . . . . . . . . . . . . 78
Variation in shoreline change rates with time . . . . . . . 78
Changes in island width and position . . . . . . . . . . . 84
PART V: PREDICTION OF FUTURE SHORELINE CHANGES . . . . . . . . . . . . 92
Temporal Predictions . . . . . . . . . . . . . . . . . . . . . . 92
Spatial Predictions . . . . . . . . . . . . . . . . . . . . . . . 92
Barrier island migration and narrowing . . . . . . . . . . 93
Alongshore sediment transport reversal . . . . . . . . . . . 96
Sound shoreline change . . . . . . . . . . . . . . . . . . . 97
Inlets and shore erosion . . . . . . . . . . . . . . . . . 99
Capes and shoreline change . . . . . . . . . . . . . . . . . 102
Shoreface-connected ridges and shoreline change . . . . . . 103

Page
PART VI: SUMMARY AND CONCLUSIONS . . . . . . . . . . . . . . . . . . . 106

REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

NOAA/NOS shoreline movement maps, 1852-1980, are shrink-
wrapped as a separate enclosure to this report.

LIST OF TABLES
No. Page
1 References to Maps and Charts Used to Establish Historic
Inlet Locations . . . . . . . . . . . . . . . . . . . . . . . . . 18
2 History of Rudee Inlet, Virginia . . . . . . . . . . . . . . . . . 20
3 Coastal Structures, Cape Henry to Cape Hatteras . . . . . . . . . . 41
4 Historic Shoreline Surveys, Cape Henry to
Cape Hatteras, 1847-1980 . . . . . . . . . . . . . . . . . . . . . 46
5 Ocean Shoreline Changes in Virginia West of Cape Henry . . . . . . 59
6 Ocean Shoreline Changes in Virginia South of Cape Henry . . . . . . 59
7 Ocean Shoreline Changes in North Carolina North of
Cape Hatteras . . . . . . . . . . . . . . . . . . . . . . . . . . 6o
8 Ocean Shoreline Changes West of Cape Hatteras . . . . . . . . . . . 61
9 Sound Shoreline Changes, Cape Henry to Cape Hatteras . . . . . . . 63
10 Pamlico Sound Shoreline Changes West of Cape Hatteras . . . . . . . 64
11 Summary of Mean Shoreline Changes, Oceanside . . . . . . . . . . . 82
12 Summary of Mean Shoreline Changes, Soundside . . . . . . . . . . . 82
13 Combined Ocean- and Soundside Shoreline Changes . . . . . . . . . . 85

LIST OF FIGURES

1 Location map . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2 Cape Hatteras viewed toward the northwest . . . . . . . . . . . . 13
3 Frontal dune along the Atlantic Ocean side of Hatteras Island . . . 13
4 Jockey's Ridge at Nags Head, N. C., rises almost 50 m . . . . . . 14
5 Sand dunes encroaching on cottages and a forest at Kill
Devil Hills, N. C . . . . . . . . . . . . . . . . . . . . . . . . 14
6 Pea Island, N. C., viewed south across Oregon Inlet . . . . . . . 15
7 Relic beach ridges at Cape Henry, Va . . . . . . . . . . . . . . . 15
8 View north across Oregon Inlet . . . . . . . . . . . . . . . . . . 16
9 Locations of persistent inlets reported open on maps and charts
between Cape Hatteras and Cape Henry from 1585 to 1980 . . . . . 17
10 Inlet channel, possible related to the now-closed Trinity Harbor
Inlet, in Currituck Sound west of the CERC field research
facility . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
11 Barrier Island width versus duration of time inlets were open
after 1585 between Cape Hatteras and Cape Henry . . . . . . . . . 24
12 Probable site of a large pre-1585 inlet at Kitty Hawk, N. C . . . . 27

No. Page
13 Continental shell profiles taken between Virginia Beach, Va.,
and Hatteras Island, N. C., to 30 km from shore . . . . . . . . . 28
14 Tide ranges, Cape Henry to Cape Hatteras . . . . . . . . . . . . . 30
15 Tide frequencies for ocean shoreline at Kitty Hawk, N. C., for
several classes of storms: (a) landfalling, (b) alongshore,
(c) inland, (d) exiting hurricanes, (e) winter storms,
(f) all storms . . . . . . . . . . . . . . . . . . . . . . . . . 31
16 Surface wind roses, Cape Henry and vicinity, from data
collected 1850-1960 . . . . . . . . . . . . . . . . . . . . . . . 33

17 Surface wind roses, Cape Hatteras and vicinity, from
data collected 1850-1960 . . . . . . . . . . . . . . . . . . . . 34
18 Annual cumulative significant wave height distribution based
on 20 years of hindcast data measured at 10-m water depth
off Kitty Hawk, N. C . . . . . . . . . ... . . . . . . . . . . . . 35
19 Wave rose diagram showing the significant wave height and direc-
tion of wave propagation for combined 20-year hindcast data in
10-m water depth at station 81 off Kitty Hawk, N. C . . . . . . . 36
20 Yearly storm surge return period for extratropical storms at
Hampton Roads, Va . . . . . . . . . . . . . . . . . . . . . . . . 37
21 Number of tropical cyclones reaching the North Carolina
coast, by sector, for the period 1886-1970 . . . . . . . . . . . 38
22 Recreational Pier at Virginia Beach, Va., a typical fishing
pier for the study area . . . . . . . . . . . . . . . . . . . . . 39
23 View toward north of groins near Cape Hatteras Lighthouse . . . . 40
24 Weir jetty system at Rudee Inlet, Virginia Beach, Va . . . . . . . 42
25 U. S. Geological Survey 1:24,000 quadrangles used as base
maps in the study . . . . . . . . . . . . . . . . . . . . . . . . 45
26 Digitization procedure for correcting shoreline position loca-
tion when original shoreline movement map distortions exist . . . 52
27 Definition sketch illustrating parameters used to obtain
shoreline change rates for a north-south-trending ocean
shoreline . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
28 Ocean shoreline change rates from near Cape Henry to Cape
Hatteras, from about 1850 to 1980 . . . . . . . . . . . . . . . . 65
29 Standard deviation of ocean shoreline position changes between
Cape Henry and Cape Hatteras . . . . . . . . . . . . . . . . . . 66
30 Average ocean shoreline change rates for the 36-km-long reach
south of Cape Henry in the periods 1859-1925 and 1925-1980 . . . 67
31 Average ocean shoreline change rates for two survey periods in
the reach between Duck, N. C., and Cape Hatteras . . . . . . . . 68

No. Page
32 Average ocean shoreline change rates at Virginia Beach for four
successive surveys between 1925 and 1980: (a) 1925-1942(44),
(b) 1942(44)-1962, (c) 1962-1980 . . . . . . . . . . . . . . . . 69
33 Extreme ocean shoreline excursions from about 1850 to 1980,
Cape Henry to Cape Hatteras . . . . . . . . . . . . . . . . . . . 70
34 Sound shoreline change rates for the reach between Back Bay, Va.,
and 12 km west of Cape Hatteras . . . . . . . . . . . . . . . . . 72
35 Standard deviation of sound shoreline position changes between
Cape Henry and Cape Hatteras . . . . . . . . . . . . . . . . . . 73
36 Average sound shoreline change rates, for the periods from about
1850 to 1915 and from about 1915 to 1980, between Nags Head
and Cape Hatteras, N. C . . . . . . . . . . . . . . . . . . . . . 74
37 Changes in ocean and sound shorelines adjacent to Oregon Inlet,
N. C., for five surveys between 1852 and 1980 . . . . . . . . . . 75
38 Migration rates of Oregon Inlet throat for five survey intervals
between 1849 and 1980 . . . . . . . . . . . . . . . . . . . . . . 76

39 Relative locations and orientations of the narrowest section
of the Oregon Inlet throat, 1849-1980 . . . . . . . . . . . . . . 77
40 Plan view changes in land area in the vicinity of Oregon Inlet,
N. C., 1849-ig8o . . . . . . . . . . . . . . . . . . . . . . . . 77
41 Changes in mean high-water shoreline at Cape Point, Cape
Hatteras, between 1852 and 1980 . . . . . . . . . . . . . . . . . 79
42 Relative plan area of the subaerial projection for Cape
Hatteras, 1852-1980* . . . . . . . . . . . . . . . . . . . . . . . 80
43 Location of Cape Hatteras point between 1952 and 1990 . . . . . . 80
44 Changes in mean high-water shoreline at Cape Henry between
1852 and 1980 . . . . . . . . . . . . . . . . . . . . . . . . . . 81
45 Shoreline change rates, averaged by survey period, for east-
facing ocean shorelines and west-facing sound shorelines . . . . 83
46 Shoreline change rates, averaged by survey period, for west-
facing ocean and sound shorelines . . . . . . . . . . . . . . . . 83
47 Island width changes between about 1850 and 1980, from Cape
Henry to west of Cape Hatteras . . . . . . . . . . . . . . . . . 87
48 Island width change rates, 1852-1917 and 1917-1980, between
Kitty Hawk and Cape Hatteras, N. C . . . . . . . . . . . . . . . . 88
49 Rates of position change of island axis between about 1850 to
1980, Cape Henry to west of Cape Hatteras . . . . . . . . . . . . 89
50 Rates of position change of island axis, 1852-1917 and
1917-1980, between Kitty Hawk and Cape Hatteras, N. C . . . . . . 90
51 Relationship of apparent ocean shoreline change to Capes,
shoreface-connected ridges, and Oregon Inlet . . . . . . . . . . 94

No. Page
52 Ocean shoreline changes from about 1850 to 1980, Cape Henry
to Cape Hatteras, as a function of island width in 1980 . . . . . 98
53 Sound shoreline changes from about 1850 to 1980, Cape Henry to
Cape Hatteras, as a function of island width in 1980 . . . . . . 99
54 Bathymetry seaward of the ocean shore between Cape Henry and
Cape Hatteras . . . . . . . . . . . . . . . . . . . . . . . . . . 104
55 Shoreline orientation referenced to true north between Cape
Henry and Cape Hatteras . . . . . . . . . . . . . . . . . . . . . 105

CONVERSION FACTORS, INCH-POUND TO METRIC (SI)
UNITS OF MEASUREMENT

Inch-pound units of measurement used in this report can be converted to metric
(SI) units as follows:

Multiply By To Obtain
cubic yards 0.7645549 cubic meters
feet 0.3048 meters

inches 0.0254 meters
knots (international) 0.514444 meters per second
miles (U. S. statute) 1.609347 kilometers
miles per hour 1.609347 kilometers per hour

SHORELINE MOVEMENTS

Report I

CAPE HENRY, VIRGINIA, TO CAPE HATTERAS, NORTH CAROLINA, 1849-1980

PART 1: INTRODUCTION

1. This report describes results of a cooperative National Oceanic and
Atmospheric Administration (NOAA), National Ocean Service (NOS), and U. S.
Army Engineer Waterways Experiment Station, Coastal Engineering Research
Center (CERC), study of shoreline changes. The study area comprises the ocean
coast south from Cape Henry, Virginia, to west of Cape Hatteras, North Caro-
lina, and the sound-side coast of the barrier islands between each of the
Capes (Figure 1). Changes in shoreline position from 1852 to 1980 are treated
using survey data from NOS and its predecessor, the U. S. Coast and Geodetic
Survey (C&GS). (NOAA/NOS-CERC shoreline movement maps, 1852-1980, are in-
cluded as a separate enclosure to this report.)
2. Shoreline changes of a quantifiable nature are presented covering
what is probably the longest period of historic survey record of the area
available. Although maps exist dating back to 1585 (Cumming 1966), prior to
1849 the position of the shoreline was not located with sufficient accuracy to
allow a comparison of that feature on different maps. The early maps, however,
do provide a valuable reference for locating inlets that were open during the
past 400 years. Langfelder et al. (1970), in a study of coastal erosion in
North Carolina, used aerial photographs dating from 1945, for which measure-
ments were made at approximately 300-m intervals along the beach. Dolan
et al. (1979) also using aerial photographs but measuring at 100-M intervals,
established erosion rates in Virginia, North Carolina, and elsewhere, based
upon data spanning 30 years or more for over half the area and over 15 years
for the whole area. Dolan et al. (1979, p 603) note their total measurement
error as potentially as much as t25 m for rate-of-change calculations. The
frequency of the aerial survey was much greater than that of shoreline surveys
used in this study, but the total aerial study duration was less than 25 per-
cent that of this study. This longer data span (130 years) allows a more
extended analysis of temporal variations in shoreline change rates.

LONGITUDE
6 07
37'00 + CHESAPEAKE '75'59
BA Y LATITUDE
CAPE HENRY 36`55

VIRGINIA BEACH 50'
NOR@ O@ K RUDEEINLET
36 45'

40
BACK
BA Y
35
@Ll RGINIA
36 30 + NORTH CAROLINA 36@30'

25:

COROLLA
C' 20'

36 15
7-

DUCK 10,

KITTY HAWK
05,

CROATAN SHORES
SOUND MILL DEVIL HILLS) 36-00
Z6 00 ALOE M@RLE NAGSHEAD
4:719
MANTEO BODIE IS,
50'
WANCHIESE
OREGONINLET
35'45
PEA IS.

40
SCALE
20 10 0 20 40 KM RODANTHE 35
WAVES
SALVO
35 30 + J5130'

25'
.10 AVON 20'
HATTERASIS
CO BUXTON J5 15'
9 HATTERAS CAPE HA TrERAS
,,O%p HAFTERASINLET LONGITUDE
OCRACOKE IS '5'31

75'36'
OCRACOKE
35'00'+ + INLET +

Figure 1. Location map (the study area shoreline is shown as
a heavy line; data are not available where the heavy line is
dashed. The northwest boundary of the study area is 12 km
west of Cape Henry at the Chesapeake Bay entrance; the south-
west boundary is 8 km west of Cape Hatteras)

3. This report provides a long-term basic data set for use in manage-
ment and engineering decisions related to the coastal zone. In the absence of
other data, past shoreline changes usually provide the best available basis
for predicting future changes. An extrapolation of past changes is not with-
out risk, though. Man's actions may have affected the natural coastal change
processes and thereby altered the rates of change. Probably more importantly,
the material processes themselves may have altered over time t@ereby varying
the shoreline change rate; Hayden (1975), for example, has identified rela-
tively large changes in storm-wave climate in this century at Cape Hatteras.
4. Historic shoreline change data are direct, believable, and explicit
and can be updated as new data become available. Shoreline changes obtained
from historic charts for a specific time period also are invariant. Past
shoreline changes based on NOS surveys can be supported in a court of law.
S. Coastal engineers use past shoreline changes in the design of proj-
ects for shoreline stabilization, flood prevention as a result of storm surges,
and maintenance of navigable depths in coastal waterways. A knowledge of past
changes in shoreline position is a useful and often necessary basis from which
to predict the effects of natural processes and proposed modifications on the
coastal zone.
6. This is an empirical report. It serves to explain and enhance the
shoreline change maps which go with it. Since it is sometimes difficult to
determine trends from maps alone, average changes have been calculated for
each minute of latitude (north-south-trending shoreline) and longitude (east-
west-trending shoreline). Relationships are established between the shoreline
change rates and (a) shore orientation, (b) location of capes, (c) proximity
to present inlets and inlets that were historically open, (d) shore-connected
ridges, and (e) an alongshore sediment transport nodal reach. A brief de-
scription of wind, wave, tide, and sedimentological parameters in the study
area is provided in Part II for readers interested in those factors; however,
because their records are insufficiently detailed or too short with respect to
shoreline changes, these parameters are not used further in this report.

PART II: STUDY AREA

Geographical Setting

7. The study area encompasses 210 km of Atlantic Ocean barrier island
coast. It begins in the north 12 km west of Cape Henry, Virginia, and extends
south to 8 km west of Cape Hatteras, North Carolina (Figure 1). A bay and
four sounds back the barrier islands along the southern 175 km,of ocean shore.
These include Back Bay, Currituck Sound, Albermarle Sound, Roanoke Sound, and
Pamlico Sound. Presently, only Oregon Inlet connects a sound and the ocean
in the study area. Rudee Inlet provides ocean access from a small lake near
Virginia Beach.
8. Currituck Banks now extends south from Back Bay, Virginia, to
Oregon Inlet, North Carolina. A past segment of the Banks from the vicinity
of Kitty Hawk, North Carolina, to Oregon Inlet is still called Bodie Island.
Beyond Oregon Inlet, the barrier is known as Pea Island about as far south as
Rodanthe, North Carolina, and as Hatteras Island from Rodanthe to Hatteras
Inlet, North Carolina; the boundary between the two lies at the site of now-
closed New Inlet. Hatteras Island is sharply angled to the southwest at Cape
Hatteras. The Cape is one of the most conspicuous cuspate headlands along the
Atlantic Coast (Figure 2).
9. The barrier islands vary in width from 0.5 to almost 5 km. A
frontal dune backs most of the barrier beach (Figure 3). Dunes west of the
frontal dune, most notably Jockey's Ridge, North Carolina (Figure 4), also are'
found along some sections. Hennigar (1979) found these dunes to be moving to
the southwest at Kill Devil Hills) North Carolina (Figure 5), and elsewhere.
In most locations, aeolian, overwash, and relict flood-tidal delta flats ex-
tend from the dunes to the sound (Figure 6). Relic beach ridges exist in the
flats area at Kitty Hawk, west of Cape Hatteras, and at Cape Henry (Figure 7).
10. Sand size varies in an alongshore direction, across the beach and
from season to season. From the Virginia-North Carolina line to Cape Hatteras,
the median foreshore sand size is 0.44 mm, with a slight average increase from
north to south (Shideler 1973). Within this area, the beach from between
Corolla and Duck to Kitty Hawk, North Carolina, is composed of anomalously
large, iron-stained quartz and feldspar sand in the 1-mm-diameter range.
Beach sand north of the States boundary is finer. Average dune sand size in

Figure 2. Cape Hatteras viewed toward the northwest (the Atlantic
Ocean is in the foreground; Pamlico Sound is in the background)

@7-7'

Figure 3. Frontal dune along the Atlantic Ocean side of
Hatteras Island between Salvo and Avon, N. C.

,MOOR"
TWWW
44

Figure 4. Jockey's Ridge at Nags Head, N. C., rises almost 50 m (the
Atlantic Ocean shore is in the foreground; Albemarle Sound is in the
background) (Hennigar 1979)

77777---7-- 7-

"Pit
A',

Figure 5. Sand dune encroaching on cottages and a forest at Kill Devil
Hills, N. C. (dune movement is to the southwest; i.e., toward the left
background of the photograph)

.... ...... .

Figure 6. Pea Island, N. C., viewed south across Oregon Inlet (overwash
and flood-tide delta flats comprise most of the western two-thirds of
the island; the Atlantic Ocean is at the left; Pamlico Sound is at the
right of this photograph)

1_0

Figure 7. Relic beach ridges at Cape Henry, Va. (these ridges formed in
the past as the cape built north and eastward; Virginia Beach is at the
foreground)

the study area is 0.27 mm and does not vary from north to south.

Historic Inlets

11. Inlets have played and continue to play an important role in shore-
line evolution in the study area. At present only two inlets, Rudee and
Oregon, are open; in the past as many as seven have been open simultaneously.
The inlets act as traps for littoral sediments which move into the lagoons
from adjacent ocean beaches and in this way contribute to ocean shoreline re-
treat. The sound shoreline is often moved toward the mainland by sand accre-
tion in flood-tidal deposits behind the islands and adjacent to open inlets
(Figure 8). Closed inlet locations are frequently distinguishable by a bulge
in the sound shoreline.

Inlet location
12. Figure 9 shows the extent of inlets reported open since 1585 on

On-

'7"

Figure 8. View north across Oregon Inlet (most of the
large shoreline lobes and islands in Pamlico Sound at
the left are relic flood-tidal shoals and other inlet
features created as Oregon Inlet migrated south; the
sound shoreline, therefore, moved west as the inlet
trapped beach sand)

CHESAPEAKE MAP OR CHART Is m
BAY DATE AND REFERENCE
CAPE HENRY LATITUDE I t I I I I I
36'65'

VIRGINIA BEACH so, ...
K RUDEEINLET
NORFOL D
-N- 36*45'

7
BACK _A 40'
BAY
KIRGINJA_ 35'
NORTH CAROLINA
36-30' + 36-30' A
C ... T.C.
A A C...
CIAROTUCK A
25'
COROLLA
20'
C)
M
>
36*15'
7-
T-ITE ......
DUCK
10*

KITTY HAWK 05'
SOUND CROATAN SHORES
346r'00' ALEICIARL-0 (KILL DEVIL HILLS) 36'00'
NAGS READ
0@ MANTE '00 BODIE IS. 55' ..
WANCHESE 50, . "N.K
..E..N -.0N
OREGONINLET
0 ....
35*45'
PEA IS.
ICANANDO C,,-,-K1-.
40' OGGFRIEAD
SCALE A
19
20 10 0 20 40 KIM RODANTHE 35' NEW
- WAVES s 1.
SALVO 21.
35-30' + 35*30' El OGG-E,
LEGEND
25' INLE IT" SA EASIM(LAR NAME
SITEDTATWSAME/ EAPSYLOCATION
INLET WIT DIFFERENT/NO NAME
1.60 AVON 20' SITED AT SIM LAR LOCATION
A LARGE PROMINENT INLET NAMED IN
co HA TTERAS IS SOURCE
BUXTON 35'15' 8 LARGE INLET UNNAMED IN SOURCE
HATTERAS CAPE NA rTERAS C WALL IN LE T OPE N I NG INTO A SOUND
D WALL INLET WITH NO ADJACENT
SOUNO

Figure 9. Location of persistent inlets reported open on maps and charts between Cape
Hatteras and Cape Henry from 1585 to 1980 (Table I lists map and chart dates and
secondary references; inlet names are shown here as they appear in the sources. Inlets
with solitary boxed letters (see Legend) appear to have been isolated in time and lo-
cation; solid and stippled bars (see Legend) show time connections between open inlets
in consecutive sources) (Caffeys Inlet data from Fisher (1962))

Table 1
References to Maps and Charts Used to Establish
Historic Inlet Location (Figure 97

Reference
Number
(Fig. 9) Date Author Secondary Reference
1 1585 White Cumming (1966)
2 1590 White-DeBry Cumming (1966)
3 1606 Mercator-Flordius Cumming (1966)
4 1657 Comberford Cumming (1966)
5 1672 Ogilby-Moxon Cumming (1966)
6 1733 Moseley Cumming (1966)
7 1770 Collet Cumming (1966)
8 1775 Mouzon Cumming (1966)
9 1808 Price-Strother Cumming (1966)
10 1833 MacRae-Brazier Cumming (1966)
11 1952 NOAA/NOS-CERC shoreline change maps*
12 1859 NOAA/NOS-CERC shoreline change maps
13** 1861 Bachman Cumming (1966)
1861 Colton Cumming (1966)
15 1865 U. S. Coast Survey Cumming (1966)
16 1882 Kerr-Cain Cumming (1966)
17'-'- 1896 Post Route Map Cumming (1966)
18 1917 NOAA/NOS-CERC shoreline change maps
19 1949 NOAA/NOS-CERC shoreline change maps
20 1962 NOAA/NOS-CERC shoreline change maps
21 1975 NOAA/NOS-CERC shoreline change maps
22 1980 NOAA/NOS-CERC shoreline change maps

Published as a separate inclusion to this report.
Maps not discussed in Fisher (1962).

the maps and charts of the times found in Cumming (1966), on NOAA/NOS-CERC
shoreline change maps dating from 1852, or, in the case of Caffeys Inlet, ac-
cording to data collected by Fisher (1962). The following inlets warrant
specific comment on their locations as shown in Figure 9.
13. Rudee Inlet. The inlet shown at approximately 36'48' in several of
the very early maps (1585, 1590, and 1606) was located by position in relation
to geomorphic features rather than by latitude, since latitude was less ac-
curate for location purposes prior to the late 1700's. The inlet was possibly
open in 1682 (Cumming 1966, figure on p 14); however, on a copy of a 1682 map
"Rudee" was written next to a lake which has the same general configuration of
Rudee Lake today. A history of Rudee Inlet after 1927 is given in Table 2.
14. "Back Bay" Inlet at latitude 36133'-34' (1590, 1606). On the
original maps, this inlet did not open into a large sound or bay but instead
appeared as a small indentation in the coastline. Comparing geomorphological
features and the mainland shoreline shows that this inlet sequence actually
existed just south of Back Bay, opposite Knotts Island. It was most likely
the precursor to Old Currituck Inlet which was shown in later years as having
closed at approximately this location (1833, 1861 (Colton), 1865, 1882); the
1882 map states that Old Currituck Inlet closed in 1775.
15. Caffeys Inlet at latitude 36015'. Early mention of this inlet in
a report by the North Carolina Fisheries Commission Board (1923, p 33) shows
that the inlet was open for a short time between 1780 and 1800. The location
can be deduced from the text to be south of Currituck Inlet, but no map was
included in the report.
16. Dunbar (1958, p 218) placed the inlet at approximately 36'13',
calling it Carthys Inlet and showing it open from at least 1798 to 1811. He
concluded that the inlet opened at the site of Trinity(e) Harbor (1585-?) and
that the same location was later called South Inlet (1808, 1833, 1861), though
the inlet had actually closed by that time.
17. Fisher (1962, p 90) shows Caffeys Inlet to be north of the town of
Duck at 36'15' and open from 1770 to 1811, maximum. He bases this location
on the existence of a large, relict, flood-tidal delta feature which he felt
was a more likely site than the relatively narrow segment of the island at
36*13' where the Caffeys Inlet Coast Guard Station is now located. Fisher's
location is shown in Figure 9.
18. The Price-Strother map of 1808 shows an unnamed inlet at 360111,

Table 2
History of Rudee Inlet, Virginia (from U. S. Army
Engineer District, Norfolk (1982))

Date Event
pre-1927 Shallow drainage ditch that opened and closed frequently
1927 Virginia Highway Department constructed a concrete culvert and
built a highway over it
1933 Hurricane destroyed both the culvert and the highway
1933-1952 Inlet open but less than 18 in. deep (and meandering to some
degree) ,
1952 Virginia Beach Erosion Commission organized
1953 Virginia Beach Erosion Commission constructed two short jet-
ties on either side of the inlet and a sheet pile wall on
north side
1954-1962 A fixed dredge was installed on the end of the south jetty to
bypass sand
1962 "Ash Wednesday" storm destroyed the bypassing plant
1962-present Small dredges have operated periodically with limited suc-
cess. Several commercial dredging operations have also
been completed to �6 ft* mean low water (mlw) project depth
1968 Existing jetties were extended north, by 560 ft, and south, by
280 ft, in addition to a 477-ft-long timber weir. Also, a
1001000-cu yd sand trap was dredged to -16 ft
1975 Waterways Experiment Station (WES) installed a test jet-pump
bypassing system
1975 Virginia Beach purchased the system from WES. This system was
operating through 1982
1979-spring A commercial dredge opened the filled sand trap and removed
approximately 100,000 cu yd of material
1980-spring A commercial dredge opened the sand trap and removed approxi-
mately 100,000 cu yd of material

A table for converting the inch-pound units of measure in this report to
metric (SI) units is found on page 8.

but placement by geomorphic features corresponding to current maps indicates
that the latitude is actually 36014'-15'. This is most likely the inlet known
as Carthys and Caffeys (and perha'ps South in 1861 maps).
19. South Inlet at latitude 36*16'-18'. Dunbar (1958, p 138) makes two
references to South Inlet (1830, 1833); he states that the inlet had actually
closed by the referenced time and was "...probably an example of cartographic
perpetuation of a feature no longer in existence." He gives no reason for the
change in name from Caffeys to South Inlet, though he considers them to be at
the same location.
20. South Inlet appears at approximately 36*16'-17' on the 1861 maps
that Cumming (1966) considered during his study. It is probably not signifi-
cant that South Inlet appears on the Bachman map because the map is inaccurate.
Colton also shows South Inlet on his 1861 map, but it is quite possible that
all inlets on his map should be shifted to the north by approximately 5' of
latitude; if South Inlet were shifted northward, it could be considered part
of the Currituck Inlet system found between 36.'26'-27' at that time. South
Inlet is shown in Figure 9, but it may not represent a single event at that
location.
21. Trinity Harbor Inlet at latitude 36'12'. Dunbar (1958, p 216)
placed Trinity Harbor (1585-?) at approximately 36'13' and regarded it as the
precursor to Carthys Inlet, now the site of Caffeys Inlet Coast Guard Station,
which was open from at least 1798 to 1811. Interestingly, Dunbar's location
of Caffeys Inlet is V-2' south of the large flood-tidal delta sequence at a
narrow section of the barrier beach mentioned in paragraph 17.
22. Fisher (1962, p 110) discussed the location of Trinity Harbor and
concluded that Dunbar's assumption of its location was incorrect because it
would be unusual for an inlet to open on the site of an earlier inlet. He
goes on to say that Trinity Harbor was most likely located further to the
north at 36'17' where there is a relict inlet feature (presently called
Beasley Bay).
23. The White-DeBry map of 1590 (Figure 9) shows Trinity Harbor to be
north of the wide Kitty Hawk/Southern Shores feature, directly east of a small
embayment and just south of an unnamed inlet with associated islands. Close
examination of this 1590 map and comparison with current maps suggests that a
location of 36*11'-12' is more accurate; Fisher's placement to the north by
almost 5' of latitude seems to be based almost entirely on the relict inlet

feature. In addition to the 1590 and 1606 maps, strong evidence for the
existence of Trinity Harbor Inlet at the more southerly location includes:
a. A channel of 5- to 7-ft depths (where adjacent water depths are
2-3 ft on the average) in Currituck Sound (Figure 10).
b. Inlet/channel fill sediments recorded (Field 1973) from cores
taken when the CERC Field Research Facility was constructed.
c. A slight westward bulge in the Currituck Sound shoreline which
could be the remnant of a reworked flood-tidal delta.

24. 1657 Comberford map. This map depicts two large unnamed inlets
open in the stretch of coast between Currituck Sound andpresent-day Oregon
Inlet. The two inlets extend for the equivalent of at least 5' and 2', re-
spectively, of latitude fronting Roanoke Island for most of its length; this
is probably a distortion, since earlier and later maps showed much narrower
inlets. Placement of both of these class B inlets in Figure 9 (possibly
Roanoke and Gunt) at the midpoint of the location listed on the 1657 map is
subjective.
25. Kitty Hawk Bay region at latitude 36*00' to 36115'. Three distinc-
tive features suggest a prehistoric inlet in this region:
a. A wide "field" of long beach ridges (Figure 11), recurving and
ending abruptly to the south at Kitty Hawk Bay, which could
have been formed during the migration of an inlet.
b. Kitty Hawk Bay itself and the narrow section of the barrier
island which separates the bay from the Atlantic Ocean.
c. Collington Island, a large feature composed of both sandy
areas and salt marsh, which closely resembles a relict flood-
tidal delta.

Early maps (1585, 1590, and 1606, to name the earliest) delineate this multi-
ple feature quite clearly. Therefore, depositional processes that formed the
feature were active before 1585, and the area has (approximately) maintained
its present configuration through historic time.
26. Chacandepeco Inlet at latitude 35116'-17'. In 1923, the North
Carolina Fisheries Commission Board (1923, p 17) suggested that an inlet be
opened 3 miles north of the Hatteras Lighthouse to increase the fishing poten-
tial of Pamilco Sound. This was considered to be an optimum location for an
inlet because of (a) the existence of "Cape Channel," a deep channel in
Pamlico Sound; (b) the narrowness of the island; and (c) the distance from
another major inlet. Previous existence of an inlet, however, was not

mentioned.

-A
36'14'
cli

36*12'
JARVISBURG

COASTAL
ENGINEERING
RESEARCH
CENTER
FIELD RESEARCH
FACILITY

D
36*10'

36'08'
MAMIE.

SOUTHERN.'
SHORES

3eo6, L

Figure 10. Inlet channel, possibly related the now-closed Trinity
Harbor Inlet, in Currituck Sound west of the CERC Field Research
Facility (contour lines show depth in feet)

9 ISLAND WIDTH, M DURATION OF TIDAL INLETS, YEARS
37-M + CHESAPEAKE
0.1 + 8 8
CAPE HE- LATITUDE M W Lo M V

VIRGINIA BEACH RUDEE INLET
NORFOLK RUDEE INLET so*

7-
BACK 40
OA
@LIRGIN@A_ 35
+ NOR TH CAROLINA 36'30* 11 ACTUALLY UNNAMED ON ALL MAPS
NEW CURRITUCK INLET

COROLLA
I @
20* ETO INLET
0

C
VARIABLE OF LATERAL
DUCK 10* MITRINITY HARBOR INLET MIGRATION
C, OR CARTOGRAPHIC
KITTY HAWK 06 VARIATION
SOUND CROATAN SHORES
@w- 4 ALD FILE MILL DEVIL HILLS) 36-00'
MAGSHEAD ROANOKE INLET

OREGONINLET
0OOIf Is OREGON INLET
WA 10
Is. 3V45
NO NEW INLET
X., SCALE 6a- --J
20 10 0 20 -0 X. 011M NEW LOGGERHEAD
NONE= 35
WAVES PORT FERNANDO/HATORASK/GUNT
+ SALVO 35'30 CHICKINACOMMACK INLET

AVON
-TEXAS IS 70 1 1
11 CO BUXTON 0
HATTERAS CAPE HA rTERAS 00 200 YEARS

-r1E.AS INLET
OC.ACOXE Is -rl@
OCRACOX LEGEND
35-00 + + INLET + LENGTH OF TIME (YEARS)
INLET OF SAMEISIMILAR
NAME AND LOCATION
0 2,000 4,000 6,000 8,000 WAS OPEN
ISLAND WIDTH, M LENGTH OF TIME (YEARS)
rf!q INLET MAY HAVE BEEN
BACK BAY

MUSK

CAFFEYS
I@POF

OPEN ALTHOUGH NAME
WAS CHANGEDIUNLiSTED
NORTH AND SOUTH
POSITIONS SHOWN ON
DIFFERING 1861 MAPS

Figure 11. Barrier island width versus duration of time tidal inlets were open after
1585 between Cape Hatteras and Cape Henry (width was measured on NOAA 1:80,000
(scale) Nautical Charts 1227, 12204, and 11555

27. Dunbar (1958, p 217) stated that the inlet was open from 1585 to
1687 and called Chacandepeco by the Indians. He also noted that, although
the inlet was shown on Comberford's 1657 map, it could have been copied from
earlier maps and not actually open at that time.
28. Fisher (1962, p 92-93) concluded that an inlet was open from pre-
1585 to 1672 at 36016.5'; his conclusion was based largely on the presence of
Cape Channel and the island's low and narrow profile in 1961. He showed that
this inlet was recorded as open on 11 maps between 1585 and 1657. On four of
those maps (1585, 1590, 1606, 1657), which were analyzed in this study, how-
ever,.evidence of an open inlet was lacking. During the 1962 (Ash Wednesday)
storm, an ephemeral inlet was opened at this site; because of the conflicting
evidence it was not included in Figure 9 as a persistent inlet.
Accuracy of inlet location
29. Use of past and present inlets in an attempt to develop a relation-
ship between inlets and shoreline change requires that historic, and if pos-
sible, prehistoric inlets be identified and accurately located. NOS shoreline
maps were used to compare inlet locations after 1852 with those on maps used
in Cumming's (1966) report. The locations of inlets on the NOS maps are con-
sidered accurate.
30. In Figure 9, the two positions listed for Oregon Inlet in 1861
(Bachman and Colton in Cumming 1966) are included to show the possible varia-
tion due to (a) cartographic mislocation of the inlets or (b) mislocation dur-
ing the original survey work. The Bachman map is entitled "Panarama [sic] of
the Seat of War, Birds Eye View of North and South Carolina, a part of
Georgia." It is an oblique map, very schematically drawn, lacking latitude
and longitude coordinates, and the location and existence (or nonexistence)
of particular inlets on it should be viewed with caution. The Colton map of
the same year is more accurately drawn, though its description emphasized the
railroad and overland transportation routes and no discussion of the coastline
is included. There is an obvious lack of correlation between the general
trend of Oregon Inlet's present position and the 1861 positions; however, if
the entire sequence of inlets shown on the Colton Map (i.e., Oregon, New, un-
named, and Loggerhead) are shifted to the north by 3'-5' of latitude, this
dramatic offset is eliminated. This seems to be a more reasonable solution
than keeping the inlets in their 1861-mapped position and assuming a "zig-zag"
migration pattern.

31. Navigation accuracy increased through time. Evidence of this grow-
ing sophistication in positioning tools and techniques can be seen in the
noticeable decrease in the width of the inlet sequences. Prior to the 19th
century, New Currituck, Roanoke, and Chickinacommock Inlet sequences are all
at least 5' of latitude wide, while the sequences of Oregon (assuming that
the offset of 1861 is a distortion), New, and New/Loggerhead Inlets are all
approximately 3' of latitude wide. With time, more accurate measurements re-
sulted is less lateral variation in the map position of inlets. Inlet loca-
tions on maps other than those produced by NOS are potentially inaccurate by
up to �5 minutes.of latitude (i.e., the approximate amount by which early
measurement methods could vary and still produce a map with the general con-
figuration of the existing shoreline). This reasoning could help to explain
the dramatic change in location of Roanoke Inlet between 1657 and 1770 shown
in Figure 9.
32. Another explanation for the variation over time of inlet locations
is north or south inlet migration. The NOS maps show, for example, that
Oregon Inlet has migrated south over the past 130 years, at the rate of 29 m/
year, for almost 2 minutes of latitude. If the migration sweep of other
inlets falls within the same range, an inlet remaining open for 100 years or
so could move �2 minutes in latitude.
A large shoreline bulge into the sound is often a good geomorphic
clue to the presence of an inlet which was open in the past. Currituck Inlet
is clearly related to a wide section of the island (Figure 11). Musketo.
Inlet, however appears to be located several minutes north of a large island
bulge (Figure 9); quite likely, the bulge is the site of historic Musketo
Inlet. The very large width change from Kitty Hawk to Nags Head is likely re-
lated to prehistoric Kitty Hawk Inlet (Figure 12). Roanoke Inlet, shown as
having varied widely in an alongshore distance (Figure 9), is centered at a
shoreline bulge; possibly more than one inlet existed in this reach. An
island bulge is also associated with the sites of the now-closed New and
Loggerhead Inlets shown on NOS shoreline maps (Figure 11).

Continental Shelf

34. A barrier island shoreline is to a large extent shaped by ocean
waves which move across the continental shelf onto.the shoreface and break

IF 4."

If
A

Figure 12. Probable site of a large pre-1585 inlet at Kitty Hawk,
N. C. (Inlet was located in the left-central part of the picture
(Fisher 1962). Note the longshore bar as evidenced by breaking
waves in the Atlantic Ocean at the right side of the photograph.
The Wright Brothers Memorial is located in the left foreground)

near the beach. The shoreface, or inner part of the continental shelf, has a,
concave profile; seaward of the shoreface, the continental shelf is planar
and dips away from the coast. Because wave form is modified and wave energy
is dissipated in shallow water, the width of the continental shelf is a factor
in regulating the amount of wave energy which reaches and is expended at the
coast. The shelf width to the 180-m (100-fathom) isobath narrows from 126 km
east of Cape Henry to 48 km east of Cape Hatteras.
35. Because of its decreasing width, the slope of the continental shelf
increases from north to south. Thedepth at the base of the steep, concave
shoreface also increases in that direction (Figure 13). The profiles shown
in the figure are averages of nine profiles, spaced 1.5 km apart, at each
location. An analysis of seismic data from the study area suggests the shore-
face may be resting unconformably upon older sediments of the planar and
seaward-dipping continental shelf; this implies the concave shoreface is
shaped by processes (waves, currents) active today or in the recent past.

PROFILE
10 NUMBER
1

E 10 0 0
9 0 0 0
5 2

10
0 0

20 - 0
0 3
25 -

3D -

35 -
0 5 10 15 20 25 30
DISTANCE, km

NOS
PROFILE PROFILE CHART PROFILE
NUMBER LOCATION NO. AZIMUTH LATITUDE LONGITUDE

1 V I RG I N IA BEACH, 1227 77' 36*49.18' 75*58.06'
VIRGINIA

2 SOUTH OF FRESH POND 1227 80, 36'29.38' 75'51.34'
HILL, NORTH CAROLINA

3 NAGS HEAD, 1229 6V 35'54.60' 7V35.82'
NORTH CAROLINA

4 WRECK-HATTE RAS ISLAND - GULL 1232 950 35'28.17' 75028.86'
ISLAND BAY, NORTH CAROLINA
Figure 13. Continental shelf profiles taken between Virginia Beach, Va.,
and Hatteras Island, N. C., to 30 km from shore (the averaged profile is
a solid line; dotted profile is a mathematical fit to the average pro-
file) (after Everts 1976)

36. Bathymety further seaward on the continental shelf reflects both
past and present processes. In the study area, the shelf is a broad sand plain
molded into north-south-trending sand ridges and troughs of up to 10-m relief
(Swift et al. 1978a, p 21). Two shelf-valley complexes were generated by the
landward displacement of the Chesapeake Bay and Albemarle Sound estuaries as
sea level rose in the Holocene epoch. Each complex has left an imprint on the
inner shelf: one lies seaward of the shoreface of Virginia Beach, Virginia,
and the other off Nags Head, North Carolina (Swift et al. 1978a, p 20).

37. Four clusters of closely spaced ridges trend oblique to the shore-
line and tie to the shoreface between Cape Henry and Cape Hatteras. They are,
from north to south, False Cape Shoals, Oregon Shoals, Wimble Shoals, and
Kinakeet Shoals. Swift et al. (1978b, p 270-271) note these characteristics
of shoreface-connected ridges: (a) the ridges rest on surfaces exposed as
the shoreface retreats to the west, (b) shoreface-connected ridges form angles
with the coast opening into the direction of prevailing flow (i.e., from north
to south), (c) sand on the seaward (downcurrent) flanks is finer than sand on
the landward (upcurrent) flanks, (d) ridges tend to be steeper on the seaward
side except next to their shoreface connection, and (e) ridges tend to migrate
downcoast and offshore. These ridges are emphasized because they appear to
have an influence on adjacent shoreline retreat rates.

Tides, Winds, and Waves

38. The data in paragraphs 39-46 are presented for reference only and
are not used in the analysis section; they provide background on the dynamic
conditions which have existed in recent times.

Tides and other sea level fluctuations
39. An astronomical tide is the periodic rising and falling of the
water surface resulting,from the gravitational attraction of the moon and sun
on the rotating earth. The period of a complete tidal cycle in the study
area is 12.4 hours; the mean and spring tide ranges from NOS Tide Tables for
1981 are shown in Figure 14.
40. Sometimes superimposed on the astronomical tides is storm surge;
i.e., wind and wave setup and water surface differences caused by barometric
variations. Wind setup is the vertical rise in water level at a lee shore
caused by wind shear stresses on the water surface. Wave setup is another
superelevation of the water surface, caused by the onshore mass transport of
water by waves. In the sounds 20 km or more away from Oregon Inlet, the
astronomical tide range is less than 0.3 m, but the wind setup may raise the
water surface a meter or more for a 1-year wind event. Return periods for
storm surge along the ocean shore at Kitty Hawk are shown in Figure 15 (Ho
and Tracey 1975).
41. A changing sea level occurring over a period of years may have a
profound effect on shoreline position. Changes on the order of years in sea

LONGITUDE
0
76 07'
1-0,0
P, 0 TIDE RANGE, M
37000'+ CHESAPEAKE -1 75 59'
SAY LATITUDE 0 0.5 1.0 1.5
CAPE HEIVR Y 36 055' -

VIRGINIA BEACH 50'
NORFOLK RUDEEINLEr
-PA 36045'

40'
BACK 7ft
BA Y 0 35'
36'30' NORTH CAROLINA 36 030'

25'
COROLLA
0 20'
C.
0
36 15'

0 DUCK 10,

KITTY HAWK 05,
CROA AN SHORES 0
36 00' ALOEMIIALF SOUN MILL DEVIL HILLS) 36 00'
," NAGSHEAD
0@1 55'
E 80DIE is
50'
WANCHESE 0
OREGON iwE r
o
PEA IS 35 45'

40'
20 10 0 SCALE 20 40 KM RODANTHE 35'
WAVES
35 030' + SALVO 35 030'
00 25'

AVON 20'
Cp HArTERASIS BUXTON 35 015'
ATTERAS CAPE NA rrERAS MEAN SPRING
IIA,IEIIAI,,vL,r-----_ LONGITUDE
OCRACOKE IS
4@@ 75031'
1 -175 036'
0 OCRACOKE
35 00'-4- + NLEr +

Figure 14. Tide ranges, Cape Henry to Cape Hatteras (from NOS tide
tables, 1981, for ocean sites (above mlw))

14
WRIGHT MONUMENT

LL a

LU b
X
LU
C

6 d

4
5 10 so 100 500 1000 5000
RETURN PERIOD, YEARS

Figure 15. Tide frequencies for the ocean shoreline at Kitty Hawk, N. C.,
for several classes of storms: (a) landfalling, (b) alongshore,
(c) inland, (d) exiting hurricanes and tropical storms, (e) winter
storms, (f) all storms (from Ho and Tracey 1975)

surface elevation may cause a reshaping of the beach, nearshore, and inner
continental shelf profile; a rising sea relative to land will probably cause
the shoreline to retreat.
42. Sea level change data are not available in the study area. How-
ever, tide gage records (Hicks 1981) from Norfolk, Virginia, and Charleston,
South Carolina, exist, respectively, for the periods 1928 through 1978 and
1922 through 1978. The average rate of sea level rise relative to land at
Norfolk was +4.4 mm/year, but the trend may be one of a declining rise rate
(Everts 1981); from 1940 to 1978 the average was +3.7 mm/year, or about
15 percent less than the 1928 to 1978 average. At Charleston the 1922-to-
1978 average was +3.6 mm/year, but Hicks' (1981) data show a 1940-to-1978
rate of only +2.5 mm/year and indicate a decline in the rate of sea level

rise relative to land.
4
f

b
,,,@@e
d

Wind conditions
43. Wind direction and mean scalar speed in the study area are given
in Figures 16 and 17. Mean annual velocities increase slightly to the south.
A velocity of 16 km/hour, 10 m above the ground, is required to initiate sand
movement. Speeds of 25 km/hour are required to sustain transport (Bagnold
1941). Winds at or above these speeds are predominantly onshore from the
northeast and occur most frequently during the winter months. The effects of
northwest winds, which are potentially important, may be lessened because of
local sheltering due to forests on the west side of the barriers (Hennigar
1979).

Waves
44. Changes in shoreline configuration result from a combination of
(a) wave action which mobilizes sediment and (b) wave-, wind-,' and tide-
induced currents which transport the mobilized sediment.
45. Wave data are available from gages situated at Virginia Beach,
Virginia, and Nags Head, North Carolina (Thompson 1977). The Virginia Beach
gage, located at a depth of 5.5 to 6 m of water msl on t he north side and near
the seaward end of the 15th Street fishing pier, was a step resistance, staff
relay gage in noncontinuous operation between 1962 and 1971. At Nags Head a
step resistance, staff relay gage was in operation, with some short periods of
inoperation, between 1963 and 1972. In 1972 a continuous wire*staff gage was
installed at a depth of 5 m of water msl on the north side and 50 m from the
end of Jeannettes Fishing Pier. A third gaging site, recently operational,
is the CERC Field Research Facility, just north of Duck, North Carolina. Wave
data have been available from that site since 1979.
46. The Wave Information Study, Phase III (Jensen 1983), provides hind-
cast wave data for 20-year time periods for the study area. Using those hind-
cast results, Figure 18 shows the annual cumulative significant wave height
distribution for waves which approach from all directions at station 81 at a
10-m water depth off Kitty Hawk, North Carolina. The mean and maximum sig-
nificant wave heights are, respectively, 0.89 m and 4.70 m. Figure 19 is a
wave rose diagram for the same location off Kitty Hawk showing the significant
wave height and direction of wave propagation for the combined 20-year hind-

cast data.

JANUARY FEBRUARY MARCH

17 16
17 14 13
115 x A 13
16 2707 12 151 14 1 @
kI )1 15 2491 12 16 2829 12
15 12 k15 212' 11 4 1.I
14 14 14

APRIL MAY JUNE

15 13
14 13 12 0"' 12 9 @ 12
1 114 ' ' 1 1 121 12
14 2912 11 2620 10, 1 U I
2 - F 110, 9 10 2470 10
12 12 % 9
15 13 12 11
1

JULY AUGUST SEPTEMBER

10 -12 12 1011- 12 12 13 15 15
1 1 A I I f 11N 11 12 1
10 2974110 10 2407 11 11 2072 11
9 % % 3 )01
2 12 1

12 11

OCTOBER NOVEMBER DECEMBER

16 15 15
16 15 17 17
114 N ) 1 14 14 14 13
12 6 215 %11%
11 2314 1 2 6 1520
132 11 14 211 211
11 13 14

DIRECTION FREQUENCY:
BARS, EACH CIRCLE = 20%.

SCALAR MEAN SPEED 25% OF ALL WINDS
(KNOTS) -04- WERE FROM NORTH-
OBSERVA ION COUNT 06 EAST
07 MEAN SPEED (KNOTS)
PERCENT OF CALMS 085 10 IS INDICATED BY THE
12 PRINTED NUMBER AT
13 05 THE END OF EACH
BAR
MEAN SCALAR SPEED
OF ALL OBSERVED EAST
WINDS WAS 10 KNOTS
@ U'71 4
"I
12

14@

04
T@l 0 N 4
IT OF @COUNTO
CALMS @13.5 0@k

Figure 16. Surface wind roses, Cape Henry and vicinity,
from data collected 1850-1960

JANUARY FEBRUARY MARCH

is 17
16 17 16 18 14
17 17 % is
2069 3,
17 055 14 17 17 2269 13
Ii I %\ 2 15 2@4'
17 .115 17 16
6 is ,16

APRIL MAY JUNE

17 14
15 14 12 13 13
1 15 1 1 19 1 12 @%
15 2163 12 2079 11 11982 11
3;3' % 2 %311,
is 15 12
14 13 11

JULY AUGUST SEPTEMBER

12 oo@ 15
1 12 101, 12 11
11 N x I I I I , . /112
I 1 181910 10 1832 11 11 1829 12
1 31 1 % \ 3 'o 9; 0,
13 12
11

OCTOBER NOVEMBER DECEMBER

17
17 16 -,
if,5 16 7 14 117 14
1 15 15 16
13 1876 14 16 isio '13 16 1822'14
k 1 3 1 13' 1151
13 13 1W 15 16 15 15 .1-1

DIRECTION FREQUENCY:
BARS, EACH CIRCLE = 20%.
SCALAR MEAN SPEED 25% OF ALL WINDS
WERE FROM NORTH-
(KNOTS -04 EAST
OBSERVATION COUNT 07 06 MEAN SPEED (KNOTS)
0085 10 IS INDICATED BY THE
PERCENT OF CALMS 12 05/ PRINTED NUMBER AT
-13 THE END OF EACH
BAR
MEAN SCALAR SPEED
OF ALL OBSERVED EAST
WINDS WAS 10 KNOTS
'N
(e'D
1 *7
i@4
@t7
6

00 �44
ATION COUNT
0
N
0 LMS
T F @CA
i 3@o

Figure 17. Surface wind roses, Cape Hatteras and vicinity,
from data collected 1850-1960

Ui
x
LU

0
10-1 100 101 102
PERCENT GREATER THAN INDICATED

Figure 18. Annual cumulative significant wave height distribution based on
20 years of hindcast data measured at 10-m water depth off Kitty Hawk, N. C.
(after Jensen, draft report)

LEGEND

WAVE HEIGHT

OVER 2.99 M
80 PERCENT
60 OF WAVES
2.50-2.99 M W 0
25
t
2.00-2.49 M U)
< W 70
0 W

115
1.50-1.99 M 160

1.00-1.49 M

0.50-0.99 M
V;7
STATION 81
0.00-0.49 M JAN-DEC
58440 CASES
A
PERCENT OF WAVES A
OCCURRING FROM
THIS DIRECTION FOR
THE 20 YEARS

Figure 19. Wave rose diagram showing the 'significant wave height
and direction of wave propagation for combined 20-year hindcast
data in a 10-m water depth at station 81 off Kitty Hawk, N. C.
(from Jensen 1983)

Coastal Storms

47. Extratropical (northeasters) and tropical (hurricanes) storms play
a major role in changing the position of the shoreline. Figure 20 from Eber-
sole (1982) shows the frequency of occurrence of storm surge for extratropical
storms at Hampton Roads, Virginia, the closest tidal reference station to the
study area (about 20 km west of Cape Henry). The figure was produced using
hourly values of water level data from 1952 to 1971. Ebersole (1982) found
that about 20 years of data provided a relatively stationary tidal probability

RETURN PERIOD, YEARS
1.01 1.1 2 5 10 20 50 100 200
7

5n)4
2
cr
0 000
0
W so
3

0.001 0.1 0.3 0.5 0.7 0.8 0.9 0.95 0.98 0.99 0.995
FREQUENCY OF OCCURRENCE

Figure 20. Yearly storm surge return period for extratropical
storms at Hampton Roads, Va. (after Ebersole 1982)

density function. Figure 20 illustrates the yearly return period for extra-
tropical storms which produce the given storm surge elevations.
48. 'Hayden (1975) studied secular variations in storm occurrence. In a
hindcast study of extratropical storms (i.e., with waves greater than 1.6 m),
he found that storm occurrences were at a maximum in March between 1942 and
1960, but that the maximum had moved to January by 1974. The mean annual
number of storms with waves over 1.6 m did not vary significantly (the annual
average was about 34); however, Hayden (1975, p 982) found the number of
events in which the waves exceeded 2.5 m had increased 1.9 times between the
1942-1965 period and the 1965-1974 period. Hayden notes that the increased
frequency of large stormwaves is consistent with observed trends in shoreline

erosion.
49. Hurricanes generally move from southwest to northeast in the study
area (Ho and Tracey 1975), with an increase in the frequency of hurricanes
from Cape Henry to Cape Hatteras (Figure 21). Simpson and Riehl (1981, p 109,
292) show below-average frequencies predominated from 1895 to 1930; in 1931

TC H GH

VIRGINIA
-----------
ELIZABETH CiTY F -Z -2

ANTE
PLYMOUTH*
E 8 7 3
WASHINGTON

NEW
BE@N
MOR E H EA D
JACKSONVILLE" CITY b
J

c
WILMINGTON-

SOUTHPORT-.:
'% .. B
SOUTH CAROLINA

TC LEGEND
H
GH TC - ALL TROPICAL CYCLONES (40 MPH OR HIGHER)
H -ALL HURRICANES (74 MPH OR HIGHER)
GH - GREAT HURRICANES (125 MPH OR HIGHER)

Figure 21. Number of tropical cyclones (hurricanes) reaching the North
Carolina coast', by sector, for the period 1886-1970

hurricane frequency rose to an above average level and remained there until
1960 when another decline began.

Coastal Structures

50. Various types of structures have been constructed on the beach and
in the nearshore zone along the study area coast (Table 3). They were con-
structed to serve four general needs: recreation and research (piers, Fig-
ure 22), coastal protection (bulkheads), coastal stabilization (groins, Fig-
ure 23), and navigation improvements (jetties, Figure 24). Jetties and groins
modify the directional distribution of energy approaching the adjacent shore-
line and act as barriers to longshore sand transport; piers also modify the
movement of sand in an alongshore direction.
51. In addition to fixed coastal structures, beach fills and dunes or

-AMA-*

Z-

Figure 22. Recreational pier at Virginia Beach, Va., a typical
fishing pier for the study area (note the,shoreline bulge
created at the pier by a decrease in the rate of sediment
transport parallel to shore. The decrease probably occurred
because the pier piles created a partial obstruction to shore-
parallel flow and because the pier piles in the water dissipate
some of the wave energy)

6@
M

4
PA

77RI,

Figure 23. View toward north of groins near Cape Hatteras
Lighthouse; Cape Hatteras Point is about 1 km south of the
lighthouse (note the change in shoreline orientation at
the groin system. Sand moving from north to south is
partially trapped and held north of the groins. The beach
to the south (bottom of photograph) consequently receives
less sand than it loses, and erosion is accelerated)

Table 3
Coastal Structures, Cape Henry to Cape Hatteras-.

Location Structure Number Remarks

West of Lynnhaven
Inlet, Va. Fishing pier 1

Virginia Beach, Va. Fishing pier I

Virginia Beach, Va. Bulkhead 1

Virginia Beach, Va. Jetties 2 Rudee Inlet, South Structure, is
a weir jetty

Duck, N. C. Research pier 1 550 m long or 2 to 3 times as long
as the fishing piers located
south of Kitty Hawk, N. C.

Kitty Hawk to South
Nags Head, N. C. Fishing pier 5

Rodanthe, N. C. Fishing pier I

Salvo, N. C. Fishing pier 1

Cape Hatteras
Light, N. C. Groins 3

Oceanfront only, 1980 conditions.

igloo

Figure 24. Weir jetty system at Rudee Inlet, Virginia Beach, Va.
(Sand movement at this location is predominantly south to north
(left to right in the photograph). Sand moves over the low weir
section and is periodically pumped to nourish the recreation
beaches north of the north jetty)

sand fences have been constructed to prevent flooding from the Atlantic Ocean
and to slow or halt shoreline retreat. The most extensive beach fill efforts

have taken place at Virginia Beach, where sand has been placed on the beach
for the last 25 years: between 1952 and 1976, over 4.5 million cu m of sand
were placed along 8 km of shoreline, mostly within the 5.5-km reach north of
Rudee Inlet (Goldsmith et al. 1977). Sand sources were (a) a stockpile at
Cape Henry where material dredged from Thimble Shoal Channel in the Chesapeake
Bay entrance was stored, (b) Lakes Rudee and Wesley and Owl Creek, (c) Lynn-
haven Waterway, and (d) upland borrow sources (currently from south,of Rudee
Inlet). The net alongshore movement is about 200,000 cu m of sediment/year to
the north at Rudee Inlet. Bypassing is presently accomplished using the weir
jetty system shown in Figure 24: sand passes over the low weir crest into a
sheltered depositional basin from which it is periodically pumped north across
Rudee Inlet to the Virginia Beach problem area.
52. In response to rapid shoreline retreat north of Cape Hatteras, the

National Park Service contracted to have 240,000 cu m of sand placed on the
beach in 1966 (Dolan 1972a). That fine-grained sand, taken from Pamilico
Sound, was soon lost. Three groins were then constructed by the U. S. Navy
in 1970. Further erosion north of the groins was addressed by a beach-
replenishment project in 1972 when 170,000 cu m of beach sand from Cape Point
was placed; in 1973, 750,000 cu m were added from the same source.
53. Between 1936 and 1940, sand fences were built along various reaches
of the study area by the Civilian Conservation Corps to create and maintain
continuous dunes (Dolan 1972b). Over 900,000 m of fencing was erected on
Bodie, Pea, and Hatteras Islands, most of it near the beach. Following a
severe storm in March 1962, a dune was constructed along 30 km of oceanfront
between Nags Head and Kitty Hawk. In the 1950's and 1960's the U. S. Depart-
ment of the Interior, National Park Service, constructed and stabilized dunes
in the Cape Hatteras National Seashore (i.e., from South Nags Head to past the
southern limit of the study area).

PART III: DATA REDUCTION

Data Sources

54. Forty-two historical NOS and C&GS shoreline surveys and maps, at
scales varying from 1:5000 to 1:40,000 and dating from 1849 through 1975,
exist for the study area. The earliest surveys (up to around 1927) were
"topographic surveys" and were practically all completed by planetable. Since
1927, aerial photography and photogrammetric methods (thus photogrammetric
surveys) have been used increasingly to provide topographic information along
the coast (Shalowitz 1964, p 52)_
55. Eighteen 1:24,000-scale U. S. Geological Survey (USGS) quadrangles
were selected to be the base maps for this project (Figure 25). They were re-
vised by the Cartographic Revision Section of the Photogrammetry Division of
NOS with 1:24,000-scale color photography, taken on 16 March 1980 at near high
water, covering both sides of the barrier island and all of the ocean coast
within the project. This procedure is described more fully below. The
historical sheets available for each base map, with their scales and dates of
survey, are listed in Table 4. A particular sheet may often be listed on more
than one base map; each base map usually comprises sheets of varying scales
and area limits.

Shoreline Definition

56. Topographic surveys, in support of hydrographic surveys, have been
compiled by NOS since the early 1800's. These surveys are the basis for the
delineaton of the shoreline on the nautical charts published by the Agency.
According to Shalowitz (1964), the authority on the historical significance
of early topographic surveys of NOS, "The most important feature on a topo-
graphic survey is the high-water line." High-water line (HWL) is a general
term; because it is used in this report as the shoreline, it must be defined
as actually surveyed through the years by NOS and its predecessors.
57. About 1840, Ferdinand Hassler, the first Superintendent of the
Survey, issued the earliest instructions for topographic work. Those instruc-
tions (Volume 17, Coast Survey, Scientific, 1844-1846, handwritten) included
the following:

LONGITUDE
07

3 7 00' + CHESAPEAKE '5 59
BA Y 43 LATITUDE
CAPE HENRY 36 55

VIRI INIA BEACH 50*

'@ORF (;.
44 'r,A 36 45
45
7- 40
7ft

46 15
@@I RGINI.@_
36 30 + NORTH CAROLINA 48 36 30
25
4i
0"
C)
49 'S
50 51

KI TY HAWK 15

SOUND 52
36 orl ALSEVApLE 53 54

MAN Q(&'@
WANCHESE 50*
ON IIVL
55 35 45
7A IS

40
SCALE 5 S
20 10 0 20 40 KM 57 1 IODANTHE 35
35@ 30 + 58 3N 30
25

59 20
CO BUXTON 3 515
CAPE HATTERAS
LONGITUDE
OCRACOKE is. 60 75 31
--T 75 36
OCRACOKE
35 00' + + ifVLET +

Figure 25. U. S. Geological Survey 1:24,000 quadrangles used as base maps
in this study

17. On the sea shore and the rivers subject to the
tides, the high and low water lines are to be surveyed
accurately; and the kind of ground contained between
them, whether sand, rock, shingle or mud marked
accordingly. The low water line is taken by offsets
whilst running the high water, and when not too far
apart from each other, but when their distance is
great they must be surveyed separately: a couple of
hours before the end of the ebb, and the same time

45
@
KI

5 2

@IAXP'Fr

Table 4
Historic Shoreline Surveys, Cape Henry to Cape Hatteras, 1847-1980

Sheet Name* T-Sheet Date of Survey Scale Map Number

Cape Henry T-507 1852 20K 1
T-753 Apr-May 1859 20K 2
T-3647 1916 30K 3
T-4139, Sect 1 Oct 1925 20K 4
T-8301 1944 20K 5
T-11704 May 1962 10K 6
T-11705 May 1962 10K 7
T-11706 May 1962 10K 8
Base map 43 16 March 1980 24K 43

Virginia Beach T-753 Apr-May 1859 20K 2
T-4139, Sect I Oct 1925 20K 4
T-8299 1942 20K 9
T-11709 Mar, May, Sept 1962 10K 10
Base map 44 16 March 1980 24K 44

North Bay T-743 ' Feb, Mar 1859 20K 11
T-4139, Sect 2 Oct 1925 20K 4
T-4139, Sect 1 Oct 1925 20K 4
Base map 45 16 March 1980 24K 45

Knotts Island T-736 Nov, Dec 1858 20K 12
T-743 Feb, Mar 1859 20K 11
T-4139, Sect 2 Oct 1925 20K 4
Base map 46 16 March 1980 24K 46

Barco NW T-657 1857 20K 13
Base map 47 16 March 1980 24K 47

Barco NE T-657 1857 20K 13
Base map 48 16 March 1980 24K 48

Barco SE T-381, Sect 1 1852 20K 14
T-381, Sect 2 1852 20K 14
Base map 49 16 March 1980 24K 49

Powells Point NE T-381, Sect 2 1852 20K 14
Base map 50 16 March 1980 24K 50

Kitty Hawk NW T-292 1849 20K 15
Base map 51 16 March 1980 24K 51

(Continued)
1J. S. Geological Survey quadrangle; see Figure 25.
(Sheet I of 3)

Table 4 (Continued)

Sheet Name T-Sheet - Date of Survey Scale Map Number

Kitty Hawk SW T-292 1849 20K 15
T-3538 1915 40K 20
Base map 52 16 March 1980 24K 52

Manteo T-351 1851 20K 16
T-3538 1915 40K 20
T-9159 Dec 1949 20K 17
Base map 53 16 March 1980 24K 53

Roanoke Island NE T-354 Jan 1849 20K 18
T-3538 1915 40K 20
T-9160 May 1949 20K 19
Base map 54 16 March 1980 24K 54

Oregon Inlet T-354 Jan 1849 20K 18
T-3538 1915 40K 20
T-9278 Dec 1949 20K 21
T-11672 1963-64 10K 22
T-11665 1963-64 10K 23
T-12140 1963-64 10K 24
TP-00887 1975 5K 25
TP-00889 1975 5K 26
Base map 55 16 March 1980 24K 55

Pea Island T-367 Mar, Apr 1852 20K 27
T-3707 1917 40K 28
T-8711, Sect 1 1946 10K 29
T-8711, Sect 2 1946 1OK 29
T-12147 May 1962 10K 30
T-12562 Oct 1963 1OK 31
Base map 56 16 March 1980 24K 56

Rodanthe T-367 Mar, Apr 1852 20K 27
T-3707 1917 40K 28
T-8712, Sect 1 1946 10K 32
T-8712, Sect 2 1947 10K 32
T-12437 April 1963 20K 33
Base map 57 16 March 1980 24K 57

Little Kinnakeet T-377 Jan, Feb 1852 20K 34
T-3707 1917 40K 28
T-8713, Sect 1 1946 10K 35
T-8713, Sect 2 1946 10K 35
T-12438 April 1963 20K 36
Base map 58 16 March 1980 24K 58

(Continued)
(Sheet 2 of 3)

Table 4 (Concluded)

Sheet Name T-Sheet Date of Survey Scale Map Number

Buxton T-377 Jan, Feb 1852 20K 34
T-790 1860 20K 37
T-1246 1872 20K 38
T-3707 1917 40K 28
T-8714, Sect 1 1946 10K 39
T-8714, Sect 2 1946 IOK 39
TP-00507 April 1974 20K 40
Base map 59 16 March 1980 24K 59

Cape Hatteras T-377 Jan, Feb 1852 20K 34
T-790 1860 20K 37
T-1246 1872 20K 38
T-3707 1917 40K 28
T-8718 1947 IOK 41
T-12442 April 1963 20K 42
TP-00507 April 1974 20K 40
Base map 60 16 March 1980 24K 60

(Sheet 3 of 3)

during the commencement of the flood tides will be the
proper time for taking the low water line, and your
operations must be so timed, as to be on the shore on
those periods.
18. You will establish points along the shores, and
mark them securely by means of stakes, At suitable
distances, for the use of the hydrographical parties
in taking their sounding--and also furnish them with
the high and low water line, from your map, they may
require.

58. The first specific instruction regarding the nature of the line to
be surveyed is contained in the Plane Table Manual (Wainwright 1889), which
states: "In tracing the shoreline on an exposed sandy coast, care should be
taken to discriminate [sic] between the average high-water line and the storm
water line." Still later, Shalowitz (1964, p 1 74) elaborated by stating:
The mean high-water line along a coast is the inter-
section of the plane of mean high water with the shore.
This line, particularly along gently sloping beaches,
can only be determined with precision by running spirit
levels along the coast. Obviously, for charting pur-
poses, such precise methods would not be justified,
hence, the line is determined more from the physical
appearance of the beach. What the topographer actu-
ally delineates are the markings left on the beach by
the last preceeding high water, barring the drift cast
up by storm tides. On the Atlantic coast, only one
line of drift would be in evidence .... If only one line
of drift exists, as when a higher tide follows a lower
one, the markings left by the lower tide would be
obliterated by the higher tide and the tendency would
,be to delineate the line left by the latter, or pos-
sibly a line slightly seaward of such drift line.
In addition to the above, the topographer, who is an
expert in his field, familiarizes himself with the tide
in the area, and notes the characteristics of the beach
as to the relative compactness of the sand (the sand
back of the high-water line is usually less compact
and coarser), the difference in character and color
of the sun cracks on mud flats, the discoloration of
the grass on marshy areas, and the tufts of grass or
other vegetation likely along the high-water line.

59. Historical references are included to emphasize that it was the
intention of all the agency's topographic surveys to determine the line of
mean high water (MHWL) for delineation on maps. With the exception of tidal
marsh areas, where in most cases the outer limit of vegetation is mapped,
the MHWL delineated on the surveys by the experienced topographer or

photogrammetrist was that line at the time of the survey or the date of
photography.
60. With the advent of precision aerial photography, the compilation
of a "T-sheet" for photohydro support opened a new dimension in shoreline
compilation. When stereoscopic instruments and known tide data were used, the
MHWL could be accurately determined by aerial photography. This method was
.,supplemented, when possible, by profile points run from vertical bench marks
to verify the photointerpretation. When beach profiles were run on the more
contemporary surveys, they were referenced to the nearest tide station. If
this was a tertiary (i.e., temporary) station, the readings were referenced
to a primary station.

Methods Used to Revise the 1980 Mean High Water Line

61. To make this study as current as possible, 1JSGS quadrangle maps
were revised to show a 1980 MHWL. The revision was made using 1980 color
aerial photographs flown for this study. Date and time of the photography
were correlated with the stage of the tide, and a detailed stereoscopic ex-
amination of the photographs was made to determine the 1980 MHWL. This pro-
cess was completed by the Cartographic Revision Section of the Photogrammetry
Division of NOS. Their method was by direct transfer of the photointerpreted
line (see paragraph 60) from 1:24,000-ratioed film positives to the USGS base
maps. Using the ratioed photography, the base maps (manuscripts) were held
planimetrically to local physical features. In absence of triangulation sta-
tions to position the manuscript accurately against the photographs, it is
possible to use "hard" planimetric features, such as road intersections or
other permanent physical structures without great relief, to assure good photo-
graphic positioning. In areas where there were not enough features to assure
proper positioning, stereomodels were set on the National Ocean Survey Analyt-
ical Plotter (NOSAP). NOSAP is a high-precision stereoscopic plotter that
allows the operator to bridge over areas of sparse control and accurately
determine the correct relationship between photographic models and the base
maps. Due to time restraints, no field check of the office-determined 1980
MHWL was made. All shorelines compiled by this method were reviewed to assure
a uniformity of the photointerpreted shoreline, accuracy of compilation, and

proper symbolization. These maps were then digitized, checked, and reviewed
in the manner identical to that used for all historical source maps.

Data Reduction Procedures

62. Copies of all historical maps used as source data in this study
were obtained from the NOS vault in Riverdale, Maryland, through the NOS Re-
production Division. Copies were initially bromide prints (a photographic
process which provides a long shelf-life copy) and were later made into more
stable matte-finish film positives. Historical sheets covering the study area
were examined to determine which sections of shoreline would be included in
the study, and those were highlighted using a yellow felt marker. Only those
areas and sections of shoreline for which data from other NOS historical maps
would be available for comparison were used.
63. Digitizing of the shoreline on each historical map and each base
map, revised for.contemporary shoreline, was the next task. This,procedure
was completed by the Data Translation Branch, Environmental Data and Informa-
tion Service, Asheville, North Carolina. The digitizing was completed on a
Calma-graphics III system, with a repeatability factor of �0.001 in. and a
maximum absolute error of �0.003 in. The digitized data tapes were then pro-
cessed using a program developed by the NOS Marine Data Systems Project for
use with the NOAA UNIVAC computer (GPOLYT2); this program allows for the con-
versions of the digitized data to geographic positions (GP's). Since many of
the historic sheets used in the study were completed before the North American
Horizontal Datum of 1927 (NA 1927) was established, the GP's for these sheets
were converted to that datum so that accurate comparisons between pre- and
post-NA 1927 surveys could be made. Conversion was completed mathematically,
based on the conversion factors for triangulation stations in the area, on a
program also written by the NOS Marine Data Systems Project.
64. After processing of the data was completed, plot tapes were gen-
erated using the NOS McGraphics program, and the plot tapes were used, with a
Calcomp 748 plotter and Calcomp 925 Controller, to plot the shoreline movement
maps. This task was completed with the assistance of the NOS Automated
Cartography Group.

Quality Control and Potential Errors

65. All sections of shoreline from the source maps were digitized so
that all shorelinepoints could be converted into GP's and replotted at any
desired scale (before the final portrayal scale of 1:24,000 for the shoreline
movement maps was chosen, other scales were tested to determine which map
scale would portray the data in the most readable form). Digitizing also re-
moved inherent media di.stortion caused by the age of the original manuscripts.
The mechanics and mathematics of the digitizing system required that all pro-
jection (latitude and longitude) intersections completely enclose the data to
be digitized. By assigning known and true values for each projection inter-
section, the GPOLYT2 program adjusted each of the shoreline points enclosed
within a projection cell, based on the true values of the intersections versus
the digitized -and computed values for those same intersections. The values
for each shoreline point are thus correct in'their position relative to the
known (true) projection intersections and to known triangulation data
(Figure 26).

+t -

+ DIGITIZED VALUES

4- CORRECTED VALUES
ADJUSTED TO TRUE
VALUESFOR
INTERSECTIONS

Figure 26. Digitization procedure for correcting shoreline position
locations when original shoreline movement map distortions exist

66. Following the digitizing process, each sheet was reviewed visually
with the use of a raw data plot in which shoreline positions were shown at the
same scale as the original map. The plotted shoreline was superimposed on the
original map and checked for completeness and accuracy of tracking during dig-
itization. This review helped to minimize a potential source of human error
that could occur during the digitizing process.

67. Other sources of potential error also were considered. The most
difficult of these to determine accurately was the location accuracy of the
MHWL on the source surveys and maps, on either (a) the early surveys prior to
approximately 1930 and (b) the group of maps based on photogrammetric surveys.
In discussing the early surveys, Shalowitz (1964, p 175) has stated:
The accuracy of the surveyed line here considered is
that resulting from the methods used in locating the
line at the time of survey. It is difficult to make
any absolute estimates as to the accuracy of the early
topographic surveys of the Bureau. In general, the
officers who executed these surveys used extreme care
in their work. The accuracy was of course limited by
the amount of control that was available in the area.
With the methods used, and assuming the normal control,
it was possible to measure distances with an accuracy
of I meter (Annual Report, U. S. Coast and Geodetic
Survey 192 (1880)) while the position of the plane-
table could be determined within 2 or 3 meters of its
true position. To this must be added the error due to
the identification of the actual mean high water line
on the ground, which may approximate 3 to 4 meters.
It may therefore be assumed that the accuracy of loca-
tion of the high-water line on the early surveys is
within a maximum error of 10 meters and may possibly
be much more accurate than this. This is the accuracy
of the actual rodded points along the shore and does
not include errors resulting from sketching between
points. The latter may, in some cases, amount to as
much as 10 meters, particularly where small indenta-
tions are not visible to the topographer at the
planetable.
The accuracy of the high-water line on early topo-
graphic surveys of the Bureau was thus dependent upon
a combination of factors, in addition to the personal
equation of the individual topographer. But no large
errors were allowed to accumulate. By means of the
triangulation control, a constant check was kept on
the overall accuracy of the work.
On aerial photographs, the MHW line is located to within 0.5 mm at map scale
(USC&GS 1944). This translates to less than 5 m on the ground for a map scale
of 1:10,000, or 9.99 m on the ground for a map scale of 1:20,000. Since the
great majority of source maps were of a larger scale than the 1:24,000 base
maps, the 0.5-mm accuracy of source maps made using aerial photography was at
least maintained by reducing most of the source maps to the common base scale
of 1:24,000. Present NOS survey maps are even more accurate. In a recent
shoreline mapping project in the state of Florida using NOS charts, 36 random

features such as road intersections and shoreline features, including points
of marsh, were scaled from the map compiled from aerial photography. Where
these features were then located by field traverse and the geodetic coordinate
values compared, the check revealed a maximum error of �3.0 m. This accuracy
is not claimed for all surveys, but it does serve as an indicator of the ac-
curacy of surveys conducted within NOS.
68. The last source of potential error is the conversion of digitized
values to GP's. Digitizing equipment automatically recorded 1,000 coordinate
values for every inch of shoreline traced, which values were then corrected
to true latitude and longitude positions, as previously discussed. The
GPOLYT2 program printout provided a final error column each for "Latitude Y"
and "Longitude X," which were examined on each printout. In the event any of
the figures exceeded 0.5 mm (at map scale), the digitizing effort was rejected
and the original sheet was redigitized. Although the maximum allowable error
from this source was 4.99 m on the ground for a 1:10,000-scale map and 9.99 m
on the ground for a 1:20,000-scale map, rarely were the error column values as
high as 0.5 mm; in most cases, they were 0.2 mm or smaller. As such, the
possible errors from this source were more likely to be in the vicinity of
1.99 m on the ground for a 1:10,000-scale map and 3.99 m on the ground for a
1:20,000-scale map. Since most data were finally portrayed at a scale smaller
than the map being digitized, the shoreline movement maps produced are well
within map accuracy standards.

PART IV: DATA ANALYSIS AND DISCUSSION

69. Reproductions of composite shoreline movement maps are enclosed
separately. These maps are useful in a qualitative way; i.e., they provide an
easy means of observing the changes that have occurred in the past. Because
of slight variations in shoreline position created in the printing process,
however, they should not be digitized for quantitative use in coastal manage-
ment, engineering, or research. To enable the data these maps represent to
be so used, the following paragraphs describe the techniques used in this
study to quantify shoreline change.
70. An analysis routine was used to average shoreline change parameters
for specified longshore distances. Because geographic point analyses were
based on latitude and longitude, a reasonable distance to use was one keyed to
those measures. Based on shore orientation, a 1-minute-latitude (about 2 km)
or -longitude (about 1.5 km) distance was selected to averagelong-term shore-
line changes. It deserves mention that the shoreline change rate given is
the average for the entire shoreline within the 1-minute coastal reach, not
the rate at particular sites 1 minute apart. The distinction is an important
one because measurements made at a constant alongshore interval seem to be
subject to a bias depending upon the particular interval chosen (Hayden et al.
1979).

Analysis Methodology

71. Shoreline change rates resulting from the following analyses,
although averages in space, are based on particular points in time. Nothing
is included that identifies what happened to the shoreline in the interval
between shoreline surveys; the analyses simply distribute the change uniformly
over the separating time increment. The rates given in this report are the
shore-normal rates of movement averaged for a fixed shore-length increment;
they were obtained using changes in plan area between successive latitude or
longitude boundaries 1 minute apart. For each survey set from time t a plan
area AW was specified using fixed latitude and longitude boundaries (three
of the boundaries used) and the shoreline (the fourth boundary) (Figure 27).'
The latitude and longitude boundaries were invariant in time; only the shore-
line boundary changed. That change in shoreline position between surveys

I'LONGITUDE

LU
A

SOUND OCEAN
SHORELINE

OCEAN
SHORELINE

Figure 27. Definition sketch illustrating parameters used to obtain
shoreline change rates for a north-south-trending ocean shoreline
(a north-south trend is defined as 3150 < a > 450)

created a change in plan area. The difference in plan area for each time
interval, divided by the shoreline length 91 and the number of years between
surveys, produced an annual shoreline change rate S for a particular survey

interval
NE

OCEAN
0
- --- TSHRELINE

A(t A(t i-1)
Si = (t i ti-1 )k (1)

where i varies from 2 to n , and n equals number of surveys. This shore-
line change rate is the average shore-normal movement landward (-) or seaward
(+) of the shoreline. This approach was used to quantify changes in both the
ocean and sound shoreline between survey dates.
72. A straight-line shoreline length Y. was used because the average
shore-normal rate of change in shoreline position was desired. Generally, the
ocean and sound shoreline orientation, a (Figure 27), did not vary at any
site by more than a degree during the study period. This indicates that shore-
line changes within 1-minute increments were mostly shore-n-ormal; i.e., the
coastline in the interval did not pivot a great deal. Therefore, the length
9. between latitude or longitude boundaries 1 minute apart remained almost
constant. The use of the straight-line distance k rather than the actual
shoreline distance was preferred on the sound side because (a) that shore was
often very irregular and (b) one objective of the study was to compare ocean
and sound shoreline changes. The sound shoreline change must, therefore, be
viewed as the average rate of shore-normal movement based on changes in plan
area and including nearshore islands. The straight-line shoreline length k
is thus a fairly constant, easily measured, and reasonable scaling factor to
transform changes in area to shore-normal shoreline changes.
73. Areas, as shown in Figure 27, were digitized at NOS for each
1-minute increment. In the sound, islands immediately off the coast were in-
cluded in the area computations because they had often been part of the coast
at an earlier time; the islands were included only when they were clearly near
the barrier island and when the sound beyond the island was open and wide.
74. The least-squares shoreline change rate S k is the slope of the
best fit line to a plot of shoreline positions A i Ik (Equation 1) versus time
of each of the surveys in that 1-minute shoreline reach, or

n
A. A
(t
S = i=l (2)
k n (t 2
n=l

where

n
I
t n t 1 (3)

and

n
n E A1 (4)
n=l

It is immaterial whether time is consistently taken as the date of the earlier
or the later of the two surveys compared. The standard deviation SD of
annual rates of shoreline change is

n 2
SD n 1 2 2: (Si (5)
i=2

where

n
1 S. (6)
n E I
i=2

Shoreline Change Rates

Listing of shoreline change rates
75. Shoreline changes, averaged (a) by varying shoreline distances
(b) over the total survey period and parts of that period, are presented
without interpretation in this section. Reasons for shoreline changes and
relationships between shoreline changes and shelf bathymetry, inlets, capes,

and shore orientation are discussed in the next section.
76. Tables 5-8 are listings of shoreline change rates for the period of
approximately 1850 to 1980 for the following ocean shoreline reaches:
Table 5: Virginia, west of Cape Henry
1

Table 5
Ocean Shoreline Changes in Virginia West of Cape Henry*

1852- Survey Dates
1852- 1852- 1859- 1916- 1944- 19 2-
Shoreline Longitude 1859 1980--'-* 1916 1916 1944 1962 1980
76006' 1.3 -o.4 -1.2 0.1 -0.9 3.7
Lynhaven Inlet
76004' 1.0 0.8 1.8 o.6 0.8
76003' 1.3 1.1 1.0 1.7 2.2
76002' 1.7 0.5 3.3 1.6 3.7
76001' -6.8 -1.2 -1.5 -0.7 -o.6 1.1
76000' -1.1 -0.7 -3.2 0.5 o.4

75059' 0.2 -0.5 1.1 0.2 2.0
Cape Henry

Shoreline change averaged between survey dates shown, in m/year; negative
value indicates shoreline retreat.
Least-squares estimate of shoreline change rate.

Table 6
Ocean Shoreline Changes in Virginia South of Cape Hen

I.Su t!s I
,gfveyID
1852- 1852- 1858- 1858- 1859- 1859- 9jg 925- 1925- 1925- 1942- 1942- 1944- 1962 -
Shoreline Latitude 1916 1980-* 1925 1980*'- 1925 1944 1980** 1944 1942 1944 1980 1962 1980 1962 1980

Cape Henry
36055' -0.5 0.2 1.1 0.2 2.0
36*541 0@5 0.7 0.4 2.9
36:53' 0.2 0.1 0.3 0.2 -0.9 1.2
36 52'@ -0.1 0.0 0.2 0.1 -0.5 0.7

Virginia Beach
36'51' -0.3 -0.2 -0.3 -0.5 -0.5 1.4
36050' 0.0 0.0 -1.7 0.2 o.6 1.4
36049, -o.6 -0.5 0.5 -6.4 -0.9 -0.8

Rudee Inlet

360481 -1.0 -0.7 -0.5 -0.1 0.1
36047' -1.0 -0.7 -1.2 -0.2 0.3
36*46' -0.9 -0.9 -2.3 -0.8 -0.1
36*45' -0.8 -1.1 -3.7 -1.4 -0.3
36144' -1.4
36*43'
360421 -2.3 -2.4 -2.5
36041, -3.4 -3.0 -2.5
36*40, -2.3 -2.1 -1.9
36*39, -1.2 -1.5 -1.8
36038' -1.3 -0.8 -0.1
36037' -1.5 -0.9 -0.1
36036'
36'351 -0.4 -0.4 -0.3
36'34' -0.5 -0.2 0.2
36033' 1.4 0.9 0.2
36*32' 1.3 1.0 0.6
36031, 2.0 1.3 0.5
36o3o, 1.6 1.1 o.4

Shoreline change averaged between survey dates shown, in m/year; negative value indicates shoreline retreat.
Least-squares estimate of shoreline change rate.

Table 7
Ocean Shoreline Changes in North Carolina North of Cape Hatteras*

Survey Bates
1849- 1849- 1849- 1852- 1852- 1872- 1915- 1915- 1946- 1949- 1949- 1963- 1963- 1975-
Shoreline Latitude 1872 1915 1980** 1946 1980** 1915 1949 1980 1975 1963 1980 1975 1980 1980

Southern Shores

36oO9' 0.0
36*08' 0.1
36*07' -0.2
36*06' 0.0 -0.5 -1.1
36*05' 0.1 -0.6 -1.4

Kitty Hawk Beach
36*04' 0.7 -0.6 -1.9
36*03' 0.7 -0.5 -1.7
36*02' 1.5 -0.4 -2.3

Croatan Shores

36*01' -1.7
36*00' -2.3
35*59' 1.2 -0.7 -4.0 -2.3 -0.4
35*58' -0.2 -0.8 -1.7 -1.3 -0.9
35*57' -1.7 -1.4 -1.1

Nags Head
35*56' -1.2 -1.3 -1.4
35*55' -1.1 -0.7 -0.2 -0.5 -0.9
35o54' -1.3 -0.7 0.1 0.3 0.5
35*53' -1.4 -1.2 -0.9 -1.0 -1.1
35*52' 0.0 -0.7 -1.8 -1.3 -0.7
35'51' -0.8 -0.8 -0.8 -0.9 1.2 -2.8
35*50' -2.0 -1.5 0.0 -1.3 -3.3 -2.3
35*49' -3.6 -3.0 -0.8 -2.7 -6.3 -3.2 -3.9

Oregon Inlet
35*45' 0.1 -4.3 -7.0
35o44' -2.8 -2.9 -2.2 -4.9
35*43' -1.9 -1.8 -0.1 -3.1
35*42' -1.7 -1.3 1.0 -1.2
35*41' 0.1 0.0 0.5 -1.7
35*40' 0.0 -0.2 -1.4 0.5
35*39' -0.1 4.8
35o38' -3.2 -1.0 0.1 1.7
35*37' -3.7 -3.8 -4.5 -3.3 -5.3 0.7
35*36' -1.5 -3.2 -4.6 -4.5 -7.1 -2.2
35*35' 0.3 -1.6 -1.9 -4.3 -2.0 -11.2

Rodanthe

35*34' -0.4 -0.2 -0.1 -0.2 1.1 -1.4
35*33' 0.4 0.3 -0.8 0.4 3.2 0.4
35*32' 0.2 -0.3 -1.0 -0.4 -2.7 2.6
35*31' -0.6 0.0 -0.2 0.7 1.3 2.1
35*30' 0.2 0.5 0.9 0.8 0.2 1.2
35*29' 1.5 0.2 -1.5 -0.8 -2.5 1.9
35*28' 1.4 0.1 -1.7 -0.8 -2.5 2.1
35*27' -0.3 -0.3 0.5 -wO.l -2.6 0.8
35*26' 1.2 -0.5 -2.4 -2.0 -2.6 -0.7
35*25' 1.5 -0.5 -4.1 -2.3 -1.3 0.5

Little Kinnakeet

35o24' 2.0 -0.3 -3.9 -2.6 -1.6 -0.8
35*23' 5.0 1.2 -5.8 -2.5 0.3 1.8
35*22' 4.0 0.2 -8.5 -3.9 1.2
35*21' 0.8 -0.5 -1.9

Avon

35*20' -0.1 -0.3 -1.3 -0.6 0.1
35*19' 0.3 -1.0 -3.2 -2.0 -1.1 1.2
35*18' -0.4 -2.0 -5.6 -3.7 -1.4 0.0
35*17' -2.4 -3.3 -5.2 -4.2 -3.2 -2.2
35*16' -2.5 -4.2 -5.3 -3.7 -3.5 -3.2
35*15' -10.2 -5.2 -6.3 -4.0 -3.2 -2.3 -1.9
35*14'

Cape Hatteras

Shoreline change averaged between survey dates shown, in m/year; negative value indicates shoreline retreat.
Least-squares estimate of shoreline change rate.

Table 8
Ocean Shoreline Changes'West of Cape Hatteras'*'.

Survey Dates
1860- 1860- 1872- 1917- 1946- 1963- 1975-
Shoreline Longitude 1872 1980-k* 1917 1946 1963 1975 1980

Cape Hatteras

75032' -1.2 7.6 11.5 10.1 -13.5 29.0 -8.1

75033' 7.0 5.6 5.7 10.5 -5.4 2.7 22.9

75034' 24.0 8.6 2.9 15.7 lo.4 -6.o 21.7

75035t 9.6 1.2 -1.8 5.9 -2.3 -1.2 2.3

75036' 3.5 -0.3 -1.3 -0.8 1.6 -o.4 3.2

Shoreline change averaged between survey dates shown; in m/year, negative
value indicates shoreline retreat.
Least-squares estimate of shoreline change rate.

Table 6: Virginia, south of Cape Henry
Table 7: North Carolina, north of Cape Hatteras
Table 8: North Carolina, west of Cape Hatteras
For the same period, Tables 9 and 10 list shoreline change rates for the fol-
lowing soundside shoreline reaches:
Table 9: Cape Henry to Cape Hatteras
Table 10: Pamlico Sound, west of Cape Hatteras
Ocean shoreline change rates
77. 1850 to 1980. The mean rate of change for the ocean shoreline over
the approximately 130-year study period is shown in Figure 28. For those
ocean reaches without rates shown, either no shoreline change values were
available (i.e., the Corrolla to Duck, North Carolina, reach), or a major
change in shore orientation (i.e., Capes Henry and Hatteras) or a break in the
barrier island system (i.e., Oregon Inlet) precluded the determination of a
usable ocean shoreline change rate. Between about 1850 and 1980 where data
were available, approximately 28 percent of the ocean shore prograded, 68 per-
cent retreated, and 4 percent did not change position.
78. Average shoreline change rates should be used with caution for
planning and design purposes because large temporal and spatial variations in
the rates have occurred in the past and can be anticipated to occur in the
future. The standard deviation of shoreline position changes with time is a
measure of these temporal variations. Large standard deviation values indi-
cate a large variability in shoreline change rates between different surveys;
smaller values indicate the shoreline change rate has been more nearly con-
stant from one survey interval to the next. Figure 29 shows the standard
deviation and the number of surveys used to calculate it for the east-facing
ocean shore. Shoreline changes north of Oregon Inlet were relatively constant
from 1852 to 1980 when compared to the changes south of Oregon Inlet to Cape
Hatteras. Greater variations in shoreline position are the norm for the
latter 60-km-long reach.
79. Partial study period. Dates of survey allow a separation of the
data set into two nearly equal time intervals. It is useful to compare ocean
shoreline changes for those two periods for several reasons. During the
period from about 1850 to 1915-1925, the shoreline underwent mostly natural
changes, except for the dune vegetation loss caused by grazing animals. Dur-
ing the period from 1915-1925 to 1980, human intervention in the form of

Table 9

Sound Shoreline Changes, Cape Henry to Cape Hatteras*

Survey Dates
Shoreline 1849- 1849- 1852- 1852- 1852- 1857- 1858- 1859- 1915- 1917- 1917- 1946- 1946- 1949- 1949- 1963- 1963- 1975-
Latitude 1915 1980** 1917 1946 1980** 1980** 1980** 1980 1949 1946 1949 1963 1980 1963 1980 1975 1980 1980
36*42' 0.3
36*41' -1.2
36*40' -6.4
36*39' -10.8
36*38' -4.1
36*37' -7.5
36*36't -1.5
36*34' -0.1
36*33' -0.4
36*32' 1.0
36*31' -4.4
36o3O' -0.4
36*28' 0.9
36*27' 2.3
36*26' -1.0
36*25' 0.1
36*24' 1.3
36*21' -0.2
36*20' 0.0
36*19' -1.6
36*18' 1.0
36'17' 2.2
36*16' 1.3
36*15' -1.3
36*14' -0.9
36*13' -0.1
36*08' -0.3
36*05' 0.1
36*04' -0.3
36*03' -1.2
36*02' 3.1
35*58' -0.7 -0.8 -1.4 -0.1
35*57' -0.2 0.2 0.9 0.2
35*56' -1.2 -1.0
35*55' 2.3 1.4 0.8 -0.9
35*54' -0.4 -0.3 -0.4 0.1
35*53' -2.8 -1.5 0.1 -0.6
35*52' 2.6 1.3 -0.1 -0.2
35*51' 13.1 6.8 0.8 -0.4 -0.1
35*50' 3.9 2.4 1.6 -0.7 0.2
35*49' 0.2 -OA -0.3 -1.2 0.3
Oregon Inlet -0.5
35'45' -1.4 -5.8 12.2
35*44' 1.3 1.1 0.7 0.0
35*43' 1.5 1.0 -0.6 -1.3
35*42' 5.3 4.2 0.1 -0.4
35*41' 11.1 8.7 -0.7 -1.1
35*40' 4.4 3.0 -3.5 -1.5
35*39' -2.2 -2.0 -1.8
35*38' 21.5 1.0 -1.5
35*37' 4.0 2.4 1.2 -0.3 -0.7
35*36' 1.4 0.3 -1.3 0.2 -0.6
35*35' -0.8 -0.4 0.1 0.2 -0.6
35*34' 0.1 -0.1 -0.4 -0.4 -0.1
35*33' -0.1 -0.4 -1.0 -0.3 -0.1
35*32' 0.4 -0.4 -1.9 -0.5 0.2
35*31' 0.6 -0.4 -2.3 -0.7 0.3
35*29' -0.8 -0.4 0.3 -0.1 -0.3
35*28' -0.7 '-0.6 -0.4 -0.5 -.0.2
35*27' -0.9 -0.8 -0.9 -0.5 -0.5
35'26' -1.2 -0.9 -0.7 -0.8 -0.4
35*25' -1.0 -0.8 -0.6 -0.9 0.0
35'24' -1.0 -0.6 0.0 -0.3 0.2
35*23' -1.4 -1.0 -0.6 -0.8 0.0
35*22' -0.9 -0.8 -1.9 0.9
35'21' -0.8 -1.3 -2.0 -1.7
35*20' -1.2 -1.1 -1.2 -0.9
35'19' -1.3 -1.0 -0.7 -0.4
35'17' -0.2 -0.1 -0.5 0.8

Shoreline change averaged between su"ey dates shown , in m/year; negative value indicates shoreline retreat.
Least-squares estimate of shoreline change rate.
t Some latitudes not included because data were unavailable.

Table 10
Pamlico Sound Shoreline Changes West of Cape Hatteras*

Survey Dates
1860- 1860- 1872- 1917- 1946-
Shoreline Longitude 1972 1980** 1917 1946 1980
75032' -0.5 -0.3

75033' -0.9 -1.1 -1.0 -1.4 -0.8

75034' 4.1 -2.5 -4.1 -3.1 -o.6

75035' -0.5 -1.5 -1.7 -1.7 -1.2

75036' 2.1 -1.5 -4.o 1.6 -1.4

Shoreline change averaged between survey dates shown, in m/year; negative
value indicates shoreline retreat.
Least-squares estimate of shoreline change rate.

OCEAN SHORELINE CHANGE, ABOUT 1850 TO 1980, IN M/YEAR
-5 -4 -3 -2 -1 0 1 2

LONGITUDE
76-07

37-00 + CHESAPEAKE
BAY ...... CC=
CAPE HENRY LATITUDE
36*55'

VIRGINIA BEACH
NORFOLK RUDEE INLET 50

16'41
r,-,J7 7
BACK 40'
BA Y C) LEGEND YICIWIZ4
--VIRGINIA- 35' 99Z
36-3V + NORTH CAROLINA 36*30 ADJACENT LINES
OF LATITUDE/
25 LONGITUDE KNOWN
COROLLA
ADJACENT LINES
20
n OF LATITUDE/ NO DATA
M LONGITUDE UNKNOWN
C 'P 36-15'
7-

DUCK 'o.

KITTY HAWK
05
SOUND CROATAN SHORES
Zoo- AeE.APLE MILL DEVIL HILLS) 36oOO
MAGSHEAD
Ln 55
N E
% 0 BODIE I&
WANCHESE 50'
OREGONINLET
PEA IS. 35-45'

SCALE 40

WAVES
20 10 0 40 KM SALVO
RODANTHE 35'

35-30' + 35-30'

#0 25*

AVON 20
%CO HA r rERAS IS. BUXTON
HATTERAS CAPE NA TTERAS 35-15,
@ mArTERAS INLET ------------ LONGITUDE
OCRACOKE 1 1 11*31
OCRACOKE 'vw 8.6
5.6
35-M + + INLET + 7.6

Figure 28. Ocean shoreline change rates from near Cape Henry to Cape Hatteras,
from about 1850 to 1980 (least-squares shoreline change rate is the slope of
the best fit line to shoreline position versus time of each survey in each
1-minute reach)

STANDARD DEVIATION OF
MEASURED SHORE CHANGE RATES NUMBER OF SURVEYS
37 DO + C.ESA1[.1F + 0 1 2 3 4 5 0 2 4 6 8
BA Y CAPE HENRY LATITUDE
36'55

VIRGINIA BEACH 50
@0.1 @A RUDtEINLET

36@45

.0
BA 7:1 :
@@IRGINIA 35 77Lr-!3
36'30 + NORTH CAROLINA 36@30

25
COROLLA

20
0

36 15

DUCK 10

KITTY HAWK
05
SOUND CROATAN SHORES
36'00 11LOM"LE WILL DEVIL HILLS1 36 N1
C, NAGSHEAD
51
MAN ED
BODIE Is
WA CHESE 50
OREGONINLEt
Z A
35 45
PEA IS

SCALE 40
20 10 0 20 .0 5.1
RODANTHE 35
WAVES
J@ 30 + SALVO 35 30

25 6.6

AVON 20
".00 CO rTIRASIS BUXTON 3515 9.4
HATTERAS CAPE HA T 15.5

r rF PAS III F T
OCRACOKE IS __,k

OCRACOKE
m + + "LET +

Figure 29. Standard deviation of ocean shoreline position changes between
Cape Henry and Cape Hatteras

artificial dune-building occurred along much of the ocean shore; it was also
in this latter period that recreation became the dominant industry in the area.
Figure 30 shows average ocean shoreline change rates for the two periods in
the 36-km-long coastal reach south of Cape Henry; Figure 31 illustrates the
same parameters for the reach between Duck and Cape Hatteras, North Carolina.
The study area was divided into two areas because of the long intervening
reach for which shoreline position data were unavailable. Shoreline change
rates at Virginia Beach, Virginia, for the most recent 55 years of survey data
are illustrated in Figure 32; they are included separately because the influ-
ence of man in recent times at Virginia Beach has increased significantly.
80. Extreme shoreline position excursion is another measure of shore-
line change variability (Figure 33). Taken over the 130-year period of record
this provides the maximum landward and seaward position to which the shoreline
moved, based on infrequently-taken survey data, the actual extreme shoreline

LATITUDE
LEGEND 36'551- CAPE HENRY
VIRGINIA
ABOUT 1858 TO BEACH
ABOUT 1925
0-6 ABOUT 1925 TO
1980 36'50'
RUDEEINLET

36'45'

36'40'

36 35' FA L E CAPE

36'30'

-4 -3 -2 -1 0 1 2
AVERAGE SHORELINE CHANGE RATES, M/YEAR

Figure 30. Average ocean shoreline change rates for the 36-km-long
reach south of Cape Henry in the periods 1859-1925 and 1925-1980
o
FALSE CAPE

6 7

LATITUDE
SOUTHERN SHORES 36*10'

KITTY HAWK
BEACH

CROA TAN 36*00'
SHORES
NAGSHEAD LEGEND

0----* ABOUT 1850 TO
ABOUT 1915
--35*50' 9---m ABOUT 1915 TO
1980

OREGON
INLET

35*40'

----------
RODANTHE

35030'

A VON 35'20'

CAPE HA TTERAS

-7 -6 -5 -4 -3 -2 1 0 1 2 3 4 5
AVERAGE OCEAN SHORELINE CHANGE RATES, M/YEAR

Figure 31. Average ocean shoreline change rates for two survey
periods (about 1850 to about 1915 and about 1915 to 1980) in
the reach between Duck, N. C. (latitude 36106'), and Cape
Hatteras (latitude 35*15')
5030'
@3

LATITUDE

CAPEHENRY

06-.
W55'- -

LEG END

1925-1942(44)
1942(44)-1962
-35*52' N 1962-1980

@RUDEE INLET

35'48' 1 1 1
-2 0 1 2 3

AVERAGE OCEAN SHORELINE CHANGE RATES, M/YEAR

Figure 32. Average ocean shoreline change rates at
Virginia Beach for four successive surveys between
1925 and 1980: (a) 1925-1942(44), (b) 1942(44)-1962?
and (c) 1962-1980

DATES NO. OF
EXTREME SHORELINE
POSITION EXCURSION, M SURVEYS
0 0 0
If) 0 co
37-00 + CHESAPEAKE 0 100 200 300 400 @20 @, @, o r.
BA Y CAPEHENRY LATITUDE -T-1
36'55'

VIRGINIA 13EACH 50'
NORFOLK RUDEFINLET

36*45

8ACK 40'
BA Y
KIRGINI@@_ 35
36'30 + NORTH CAROLINA 36'30'

25'
COROLLA DATA
0 20 @NO DATA
36'15-

DUCK 10'

KITTY HAWK 05
SOUND CROATAN SHORES
WILL DEVIL HILLS)
36-00 ALBEIARLE 36'00
NAGSHEAD
09 0 5, 408.9
MANTEO 0 BODIE IS 'DATA'
WANCHESE 50 F
PREGONINLET
0
PEA IS 35'45
457.6
SCALE 0 40
20 10 0 20 40 KM RODAN THE 35
WAVES
SALVO
35' .30 + 35'30'

25'

AVON z 20' 411.3
0 HATTERASIS 489.3
BUXTON 35., 688.4
V0 HATTERAS CAP, HArTERAS
LEGEND
HArrERASINLtr
OCRACOKE IS-*
4@@ 11 SHORE RETREAT
OCRACOKE
35"00 + + INL E T + SHORE PROGRADATION
Figure 33. Extreme ocean shoreline excursions from about 1850 to 1980,
Cape Henry to Cape Hatteras

excursion probably was larger than appears because only a few shoreline posi-
tions were measured. In over one-half the surveyed shore reach, the extreme
shoreline position change occurred between the first and last surveys, in-
dicating a relatively continuous shore retreat or advance. Because of this
trend, patterns shown in Figure 33 are similar to mean shoreline change rate
patterns shown in Figure 28. Areas of retreat are more numerous than areas

of advance.
Sound shoreline change rates
81. 1850 to 1980. Shoreline changes on the sound side of the barrier
islands exhibit few consistencies in an alongshore direction (Figure 34).
The largest retreat rates occurred in the Back Bay area, a constricted fresh-
water region reported to be free of inlets in historic time (Figure 9).
Accretionary trends adjacent to and south of Oregon Inlet appear to be inlet-
associated. The consistent 0.5- to 1.5-m/year retreat of the sound shore-
line south of Salvo, North Carolina, also occurs in an area where inlets
persistent in historic times have not been reported. Figure 35 illustrates
the standard deviation of shoreline pos'ition change in the sounds through

time.
82. Partial study period. Figure 36 shows changes in the sound
shoreline for the same periods illustrated for the ocean shoreline in Fig-
ure 31. The 1852-1980-averaged sound shoreline change rate was -0.1 m/year,
a retreat which is 13 percent of the average retreat rate (-0.8 m/year) of

the ocean shore.
83. In the sound adjacent to Oregon Inlet the standard deviation of
shoreline change (Figure 35) is very large, suggesting fluctuations that are
likely inlet-related. South of Rodanthe, the shoreline retreated in a rela-
tively continuous manner. Infrequent and severe storms probably caused the
changes in this area. However, the storm effects, which are usually localized
in time and location, were probably lost in spatial averaging, especially con-
sidering the large survey interval of this study.
Oregon Inlet
84. Oregon Inlet was opened in 1846 by a severe coastal storm. Ini-
tially, large quantities of water moved through New Inlet (Figure 9) into
Pamlico Sound. Precipitation and runoff further increased the volume of
water in the sound; when the wind direction changed to the west, some of this
ponded water was carried seaward north of the site of present-day Oregon Inlet

SOUND SHORELINE CHANGE, ABOUT 1850 TO 1980, IN M/ YEAR
LONGITUDE -8 -6 -4 -2 0 2 4 6 8
76-07*

37000 5*59,
+
BAY LATITUDE
CAPE HENRY 36*55'

VIRGINIA BEACH 50'
NORFOLK RUDEEINLET
36'45'
I-
I
7- 40'
BACK -10.8
SA Y
RGINI� _ 35'
36-30'+ NORTH CAROLINA 36*30'

26' LEGEND
COROLLA
20' -ADJACENT LINES
OF LATITUDE/
36*15'
7- LONGITUDE KNOWN

C DUCK 10' ADJACENT LINES
KITTY HAWK OF LATITUDE/ C
05' LONGITUDE UNKNOWN
CROATAN &NO ES
Zoo. 10""ALE SOUN MILL DEVIL HILLSI 36*00'
NAGSHEAD

BODIE IS.
WANCHESE 50' . . . . . .
0 OREGONINLET
PEA IS.. 35*45

SCALE 40' 8.7
20 10 0 20 40 KM RODANTHE 35' 5
WAVES
35-30' + SALVO 35*30'

'OPP 25'
VON 20'
MA TrERAS IS. BUXTON 3VIS,
HATTERAS CAPE HATTERAS
op_- 75-31'
OCRACOKEIS.-P 15"' MATTERASINIET LONGITUDE
75*36, E END =cPA1
T LINES
ADJ CEN 7
OF TI TUDE/
Lo ITU 0
-7N DE KN WN
.rNT II.I

OCRACOKE
35'00'+ + iNLEr +
Figure 34. Sound shoreline change rates for the reach between Back Bay, Va., and
12 km west of Cape Hatteras, from about 1850 to 1980 (least-squares shoreline
change rate is the slope of the best fit line to shoreline position versus time
of each survey in each 1-minute reach)

STANDARD DEVIATION OF MEASURED
37-00 + CHESAPEAKE 4- + SOUTHSIDE SHORE CHANGE RATES NUMBER OF SURVEYS
SAY CAPE HENR Y LATITUDE 1 2 3 4 5 0 2 4 6
36-55' 1
VIRGINIA REACH 50'
NORFOLK RUDEEMLET

16'41'

z
BACK t 40'
BA Y I-)
@QRGINIA 35'
36-30' + NORTH CAR3 I A 36*30'

25'
COROLLA

0 20'

36'15'
7-
0 DUCK 10'

KITTY HAWK 05'
CROATAN SHORES
SOUND 1XII
3V@00 'L60AARLE L DEVIL HILLS) 36'00
10 NAGSHEAD
5&'
0 SODIE IS
6.6
WANCHESE so
OREGON INLET
0
PEA IS. 35*45, - - - - - - - - 9.2
00
6.9
SCALE 40' 4
12.6
20 10 0 20 40 KNI RODANTME 35
M0Z3EEZNWEII:::@=I WAVES
JV30' + SALVO 35*30'
10\1 #0 AVON 25'
R 20 - - - - 39.4
T:RTERAS IS U.T.N
AT AS CAPE MA rrERAS 35oI5 .7 77'116-@.

HATTERASiNcEr
OCRACOKE Is -@;@
OCRACOK
35-00 + + INLET +
9

7k:=

Figure 35. Standard deviation of sound shoreline position changes between
Cape Henry and Cape Hatteras, from about 1850 to 1980

LATITUDE

3eOO' CROA TAN SHORES

NAGS HEAD

35@50' _J@ 13.1
LEGEND

*--o ABOUT 1850 TO OREGONINLET
ABOUT 1915
ii-a ABOUT 1915 TO
1980 35'40'

RODANTHE

i r 35030'

A VON

CAPE HA TTERAS

-4 -2 0 2 4
AVERAGE SOUND SHORELINE CHANGES, M/YEAR

Figure 36. Average sound shoreline changes, for the periods from
about 1850 to about 1915 and from about 1915 to 1980, between
Nags Head and Cape Hatteras, N. C.

(Cumming 1966). With time, a channel was cut and deepened. Tidal currents
through the inlet throat have since kept it from filling with littoral sedi-
ments carried in a shore-parallel direction.
85. The inlet has not remained fixed in its original position, nor has
its shape nor the shape of the adjacent islands remained constant. Figure 37
shows the changes that have occurred since the inlet opened. (The dashed line
is the 1849 shoreline included for comparison purposes; note that a short
reach of shoreline south of Oregon Inlet was not surveyed during the 1915-1917
period.) Between about 1849 and 1980 the average inlet migration rate (i.e.,
the shore-parallel (north-south) movement of the midpoint of the narrowest
part of the inlet throat) to the south for Oregon Inlet was approximately
29 m/year. As shown in Figure 38 this rate varied greatly from one survey
interval to the next. The most rapid movement of the midpoint, 87.5 m/year
south between 1963 and 1975, occurred just after a severe storm on 6 and
7 March when the inlet widened and migrated north.
IL

LATITUDE
3e55'

cet

SCALE

1 o 1 2 3KM

35'50'

OREGON
INLET

%
35*45'

NEW
INLET

35'40'

1946 1915-17 1849
1980 1963

36'35'

Figure 37. Changes in ocean and sound shorelines adjacent to
Oregon Inlet, N. C., for five surveys between 1852 and 1980

100 -

75 -

> 0
CCZ
M
W
Z 25
WW

cc
Z
0 25
< AVERAGE
Cr
0
W
F_0 50

Z
Z
W 75

1975
1849 1915-17 1946 1963 1980 SURVEY DATES
100 ikI I AL 1
1850 1900 1950
DATE MIDWAY BETWEEN SURVEYS
Figure 38. Migration rates of Oregon Inlet throat for five
survey intervals between 1849 and 1980

86. Figure 39 shows the relative locations and orientations of the
narrowest section of the Oregon Inlet throat measured during six surveys
between 1849 and 1980. Also shown are changes in narrowest inlet throat
width, the relative location of the center of the inlet throat, and the di-
rection of inlet throat migration. This figure emphasizes three interesting

features:
a. The width of the inlet throat in 1963, about 2.5 km, was over
twice as large as the width average which is about 1.2 km. The
throat was expanded during the storm of March 1962, mostly at
the expense of the island to the north.
b. With the exception of the 1962 storm period (1963 survey) when
the center of the inlet throat moved north, migration was in a
generally south direction.
c. Except for immediately after the 1962 storm, the orientation
of the channel at the narrowest section was approximately
north-south; i.e., a line connecting the two sides of the
inlet at its narrowest section was oriented east-west.
87. The change in land area adjacent to Oregon Inlet very likely re-
flects the inlet influence on the nearby shorelines. This land area (Fig-
ure 40) above mean high water has been declining since the inlet opened;
with the exception of the 1963-1980 interval, the loss has averaged about

1849 (1.05)

6---PA THL INE OF
L) 1963(2,50)
z INLETMIGRATION
<

1915(l.22)

0
z
1949(l.27)

1975(l.28) 0 1980 (0.901

1 1 1
EAST-WEST DISTANCE, KM

Figure 39. Relative locations and orientations of the narrowest section of
Oregon Inlet throat, 1849-1980 (dates given are dates of survey; numbers in
parentheses are inlet widths in kilometers)

10 - LEGEND

TOTAL AREA
AREA NORTH OF INLET
AREA SOUTH OF INLET

OREGONINLET

6 -
x

Cr.

0-
1849 1915 1949 1963 1980
SURVEY DATE
\
a
T
A
0TA
EA
LAREA
No RTH OF
S UT
N
1*0 AREA H F IN
0 0

OR EGON INLET

Figure 40. Plan view changes in land area in the
vicinity of Oregon Inlet, N. C., 1849-1980

-16,000 sq m/year. The land region included in the analysis extended 8 km
north and 8 km south of the inlet as it existed in 1849 (Figure 37). The net
loss for the total system, which may include some effects of New Inlet, re-
sulted from shoreline retreat adjacent to the inlet; this probably represents
a transfer of sand from the ocean shoreline region to the sound by inlet cur-
rents. Note that the decrease in plan area was continuous south of the inlet
but the variable plan area changed north of the inlet. The increase to the
north occurred as the result of a spit which built south as the inlet migrated
south.

Cape Hatteras and Cape Henry
88. The land protrusion of Cape Hatteras (Figure 2) has changed sig-
nificantly in plan area and shape since the first survey in 1852 (Figure 41).
Figure 42 shows that a decrease in land area occurred as the east-facing coast
retreated (eroded) to the west and the south-facing coast prograded (accreted).
Figure 28 shows evidence of the ocean shoreline retreat at the Cape Hatteras
lighthouse. In 1870-, when the lighthouse was built, the shoreline was 600 m
east of its 1980 position. Retreat has been continuous except for a brief
period in the 1940's where a slight progradation occurred. Figure 43 shows
that Cape Point moved about 0.5 km in a net southwesterly direction between
1852 and 1980. The figure also shows that Cape Point fluctuated greatly in
position during that period and that the present position is likely a tempo-
rary site.
89. Cape Henry, during the same period, changed in a different way
(Figure 44). The east-facing shore moved east (prograded), while the
north-facing Chesapeake Bay shore moved south (eroded). The changes at Cape
Henry were nearly an order of magnitude smaller than the changes at Cape

Hatteras.
Variations in shoreline change rates with time
90. Shoreline change rates varied greatly with time. The extent of
this variation is illustrated in Tables 11 and 12. The periods shown on the
tables, 1852-1917, 1917-1949, and 1949-1980, are expedients based on available
survey data. The shoreline change data, when averaged by reach (Figures 45
and 46) suggest these trends:
a. Shoreline retreat on the east-facing ocean coast was at a maxi-
mum during the 1917-1949 period (Figure 45). Greatest shore
stability occurred between 1852 and 1917.

75'32' 75*31' 7 5@ 30'
rt T 35* 15'
./ J 1852
1980 / I
1,975_::@ /
1963 1872
1947 It

1917

1860

35' 14'

CAPE HATTERAS

SCALE 1:24,000 35'13'
1/2 0 112 1 MI

1000 0 1000 2000 300 0 5000 6000 7000 FT

0.5 0 0.5 1 KM

Figure 41. Changes in the mean high-water shoreline at Cape Point,
Cape Hatteras, between 1852 and 1980 (dates indicate the year of
the shoreline survey)

010

RELATIVE PLAN ARE

in
En 0
SOUTH NORTH I I
0 hi

rt
0 W.

0
1-h w v

rt,H

03 c
00 to m
ct cn 0 <
C) ct m
(D to QD J.-b -<
NN, 0
rt >
00 @:r -A
Lp m

0
INA,

rt m 00 D)
> co C) m
cn ti
IT

00 m
rt (o L
co

la,
t-h
0
Pi
00
0

76002' 76001' 76'00' 75059'
36* 56'

CAPE HENRY

LEGEND -A
(SOURCE OF MEAN HIGH WATER LINE)
I z
MARCH 1980 NOS AERIAL PHOTOGRAPHY A
1962 F I E LD SU RVEY C-1

............... 1944 FIELD SURVEY

1925 FIELD SURVEY

1916 FIELD SURVEY
1859 F I E LD SU RVEY- 36055'

1852 FIELD SURVEY

0
M
00
Z
A
\jx@
NORTH
VIRGINIA
BEACH

SCALE 1:24,000 36*54'
1 1/2- 0 1/2 1 M1

1000 0 1000 2000 3000 4000 5000 6000 7000 FT

1 0.5 0 0.5 1KM
monoME:::Zz:===
1927 NORTH AMERICAN DATUM
POLYCONIC PROJECTION

Figure 44. Changes in the mean high water shoreline at Cape Henry between 1852 and 1980

Table 11
Summary of Mean Shoreline Changes, Oceanside

Mean Shoreline Change for These Survey Periods
Coastal Reach 1852-1917 1917-1949 1949-1980 1852-1980

.11
West of Cape Henry 0.2 (5)" 0.5 (7) 1.2 (7) 0.2 (7)
Cape Henry to
Oregon Inletf -0.0 (20) -1.2 (18) -0.3 (21) -o.6 (4o)
Oregon Inlet to
Cape Hatterastt 0.4 (21) -2.9 (23) -1.3 (30) -1.1 (28)

West of
Cape Hatteras 4.5 (5) 8.3 (5) 2.0 (5) 4.5 (5)
Average 0.6 (51) -0.8 (53) -0.4 (63) -0.4 (80)

Mean N-S ocean coast = -0.8 m/year; n = 75

Mean E-W ocean coast = +2.0 m/year; n = 12

Table 12
Summary of Mean Shoreline Changes, Soundside

Mean Shoreline Change for These Survey Periods, m/year-4r
Coastal Reach 1852-1917 1917-1949 1949-1980 1852-1980

West of Cape Henry -- -- -- --
Cape Henry to
Oregon Inlet 2.0 (9)** 0.1 (10) -0.2 (10) -0.5 (40)
Oregon Inlet to
Cape Hatterast 0.7 (24) 0.3 (20) -0.2 (27) 0.3 (19)

West of
Cape Hatteras$ -1.9 (4) -1.0 (5) -0.9 (5) -1.7 (4)
Average 0.7 (37) 0.1 (35) -0.3 (42) -0.3 (63)

Mean N-S sound shore = -0.1 m/year; n = 70

Mean E-W sound shore = -1.2 m/year; n = 5

Positive = shoreline moves seaward; negative shoreline moves toward
mainland.
Number in parentheses is number of 1-minute reaches included in analysis;
number varies for different time periods because surveys are not continuous
for entire coast.
t Data coverage = approx. 60 percent of total shoreline.
tt Data coverage = approx. 90 percent of total shoreline.
Data coverage (1852-1980) = approx. 80 percent of total shoreline.

2 - q11 SOUNDSIDE
C HENRY TO
OREGONINLET

SOUNDSIDE
OREGONINLET
TO C. HATTERAS

2 0

OCEANSIDE
11@sc. HENRY TO
OREGONINLET

OCEANSIDE
z jREGONINLET
-2 TO C. HATTERAS

4
1852-1917 1917-1949 1949-1980
SURVEY PERIOD

Figure 45. Shoreline change rates,averaged by survey period, for east-
facing ocean shorelines and west-facing sound shorelines

OCEANSIDE
WEST OF C. HATTERAS

4 -

OCEANSIDE
0 WEST OF C, HENRY

z 0 -

SOUNDSIOE
WEST OF
C. HATTERAS

-41
1852-1917 1917-1949 1949-1980
SURVEY PERIOD

Figure 46. Shoreline change rates, averaged by survey period, for
west-facing ocean and sound shorelines

b. The temporal trend, but not the magnitude, of east-facing ocean
coast changes was similar north and south of Oregon Inlet
(Figure 45).
c. North- and south-facing ocean coasts (Figure 46) were accre-
tional in the 5- to 10-km study reaches west of the capes for
all survey periods. The trends of change were not similar;
however, the small number of reaches sampled in each area
(Table 11) may preclude a realistic comparison.
d. The west-facing shoreline trend in the sounds was one of con-
tinuous change from progradation (movement into the sounds)
to retreat (movement toward the ocean) between 1852 and 1980
(Figure 45). The trends were similar north and south of Oregon
Inlet.
e. Between 1852 and 1980, the north-facing shoreline west of Cape
Hatteras decreased its net retreat (Figure 46). This trend was
the opposite of that measured for the west-facing sound shore-
line (Figure 45).
f. Ocean and sound shoreline changes generally did not follow
similar trends through time. While the east-facing ocean
shoreline retreated at a maximum rate between 1917 and 1949,
the west-facing sound shoreline (i.e., the shoreline on the
other side of the barrier island) reached a maximum retreat
rate in the 1949-1980 period. Only the north-facing ocean
shoreline at Cape Henry and the north-facing sound shoreline
at Cape Hatteras (Figure 46) showed similar behavioral trends
through time.
Changes in island width and position
91. Where data covering both ocean and sound shorelines are available,
an analysis of island width and position provides useful information on the
particular ways in which the islands have changed shape. When averaged for
the period of about 1850 to 1980, the east-facing ocean shore retreated an
average 0.8 m/year. In the same period the average retreat rate of the west-
facing sound shoreline was 0.1 m/year. This resulted in an average island
narrowing of 0.9 m/year.
92. Because the average ocean shore retreat exceeded the average rate
of sound shore retreat, the island axis (i.e., the midpoint between,shore-
lines) moved landward (west) an average 0.35 m/year. However, as Table 13
shows, in most time periods and along most reaches, the island axis moved sea-
ward at more locations than it moved landward. This island axis movement,
though, should not be confused with the classical definition of barrier island
migration which assumes that both oceanside and soundside shorelines move
toward the continental land mass. Island migration occurs when the o cean
shoreline erodes and, concurrently, the sound shoreline progrades as sand is

Table 13

Combined Ocean- and Soundside Shoreline Changes

Number of 1-minute Latitude/Longitude Shoreline
Increments Which Moved
Survey Period North of South of West of No
1852-1980 Oregon Inlet Oregon Inlet Cape Hatteras Total Change

Island* widens 8 4 2 14

Island narrows 16 15 2 33

Island axis moves
toward sound 12 7 0 19

Island axis moves
toward ocean 10 12 4 26

Survey Period
1852-1980

Island widens 4 9 2 15
3
Island narrows 4 7 2 13

Island axis moves
toward sound 6 6 0 12

Island axis moves
toward ocean 2 13 4 19

Survey Period
1946-1980

Island widens 1 7 2 10

Island narrows 9 18 3 30

Island axis moves
toward sound 9 12 0 21
Island axis moves 1
toward ocean 0 12 4 16

Island as shown here also includes the peninsula or spit north of Oregon
Inlet.

transported (a) across the island by overwash or wind or (b) through inlet
openings directly to the sound shoreline.
93. A general indication of island behavior is shown in Table 13 for
three regions (i.e.,.north and south of Oregon Inlet and west of Cape Hat-
teras) in the study area. Note that island narrowing, by portion of the
coast, is the most common change, while island widening is the least common
behavior. Slightly more segments of the island system moved seaward than
landward. Table 13 references direction of movement by 1-minute latitude or
longitude increments. The following four changes are noteworthy:
a. For the measured segments, island narrowing greatly exceeded
island widening when averaged for the 130-year study period.
However, during the 1852-1917 period, island widening and nar-
rowing were almost equal. Between 1946 and 1980, three times
as much of the measured island system narrowed as widened.
b. Island-narrowing-to-widening ratios were generally similar
north and south of Oregon Inlet. This suggests that the con-
ditions which led to the island width changes, while they
varied through time, were consistent throughout the study area.
c. Over the study period, the island axis moved seaward at slightly
more places than it moved landward. This situation, however,
varied by survey period. Between 1852 and 1917 seaward move-
ment prevailed, while between 1946 and 1980 landward movement
of the axis prevailed.
d. For the measured portions of the study area, trends in island
narrowing or widening did not indicate particular movements of
the island axis.
94. Figures 47-50 show the rates of island width change and the rates
of change in position of the island axis for different time periods. Fig-
ures 48 and 50 are limited to the section between Kitty Hawk and Cape Hatteras,
North Carolina, because that is the only area in which data were available for
both the periods 1852-1917 and 1917-1980. These figures illustrate the fol-
lowing alongshore changes in island width and position through time:
a. The largest island width changes occurred near Back Bay, Vir-
ginia (Figure 47). This is an area of large ocean (Figure 28)
and sound (Figure 34) shoreline retreats.
b. Increases in island width between Kitty Hawk and Oregon Inlet
(Figure 47) came as a result of progradation of the sound
shoreline (Figure 34) during a period of ocean shore retreat
(Figure 28) (the area near Croatan Shores was not influenced
by an inlet during the study period). The south-facing ocean
coast west of Cape Hatteras was also an area of island width
increase; however, here the increase occurred because of ocean
shore progradation (Figure 28).

LONGITUDE

CHANGEIN ISLAND WIDTH, MIYEAR
3-7-00 + CHESAPEAKE 75o59'
SAY LATITUDE -14 -12 -10 -8 -6 -4 -2 0 2 4 6
CAPE HENR Y 36*55' - --

V I FIG I MI A OF ACH 50'
NORFOLK RUDEEINLET 36-45'
BACK 7-A 40* OF e e
RA Y iF@ 'k
@LIRGINIA 35
C
36'30'+ NORTH CAROLINA 36*30' X? t q
=3

25'
COROLLA

36-15

DUCK 10'

KITTY HAWK D5'
SOUN CROATAN SHONE&
00 36@001 A',,,ARLE (KILL DEVIL HILLS11 36*00'
MAGSHEAD

N E
% EDDIE IS. 3Z=S=
WARCHESE 0 1.
" 1) OREGONINLET
PEA IS. 35-45'

SCALE 40'
20 10 0 20 40 KM RODANTHE 35'
WAVES
SALVO
35-30- + 35-30'

25,

AVON 20'
0 HATTERASIS
BUXTON 35-15*
,,.,I,lr 04ATTERAS CAPE MA "ERAS
IS. _.%@ :P NA rTERAS Ift ET --------- LONGITUDE
OCRACOKE I 1 :5'31*
OCRACOK 536'
3S'00 + INLET +
Figure 47. Island width changes between about 1850 and 1980, from Cape Henry
To west of Cape Hatteras

b
37-00'+ CHESAPEAKE + -CHANGE IN ISLAND WIDTH, M/YEAR
LATITUDE -8 -4 0 4 8 -8 -4 0 4 8
CAPE HENRY 35-55-

VIRGINIA BEACH 50,
NORFOLK RUDEE INLET I
36-46-

7-
&A 40
BAY 0
KIRGINIA_ 35'
36-30- NORTH CAROLINA 36-30'

25'
COROLLA

0
0
36-15

0. DUCK 10,

KITTY HAWK
05,
SOUND CROATAN SHORES
00 H
00 "'ENIARLE WILL DEVIL ILLS1 36*00'
MAGSHEAD

E
BODIE 11
IN HE so, 12.3
OREGONMET
0
PEA IS' 35'4S'
It
SCALE 40'
20 10 0 29 @OKM
RODANTHE 35'
WAVES
35-30- + SALVO 35P30'

25*

AVON 20,
TTERAS 15,
BUXTON
000CO MATTEARAS N 35-15'
CAPE NA TTERAS 1852-1917 1917-1980
HATTERASINLEr
OCRACOKE 1&-,*
4@@ SURVEY PERIOD
OCRACOK
35-00'+ + INLET +

Figure 48. Island width change rates, 1852-1917 and 1917-1980, between Kitty Hawk and Cape Hatteras, N. C.

LONGITUDE
76-07'

MIGRATION OF ISLAND AXIS, M/YEAR
37-00- + CHESAPEAKE I '..
BAY LATITUDE -4 -3 -2 -1 0 1 3 4
CAPE NENR Y 36*55'

VIRGINIA BEACH 50'
14ORFOLK RUDEEINLET
A 36'.5'

BACK 40
BAY
@LIFIGINIA_ 35'
36-30- + NORTH CAROLINA 36'30*

25
COROLLA
20'
C)
C')
36-15

DUCK 10'

KITTY HAWK 05 C:E
SOUND CROA AN SHORES
ZOO, ALOE,,ALE IKILL DEVIL HILLS1 36-00
NAOSHEAD
DO 55

80DIE IS.
WAFW#CHESE so
OREGONINLET
'1!- 35'45'
PEA IS..
20 10 0 SCALE n Q K. 1 40'
RODA THE 35
11111=111INIZZINNEEZZZ301111101=1 WAVES
SALVO
35-30- + 35'30'

25'

AVON 20'

BUXTON 35-15
HATTERAS CAPE HA
000CO "A I-TERAS IS rrERAS
OCRACOKE IS RASINLET --------- LONGITUDE
HA rTE

OC COKE
35*00 + + INLET +

Figure 49. Rates of position change of island axis between about 1850 and 1980, Cape Henry
to west of Cape Hatteras (island axis = midpoint between ocean and sound shorelines)

MIGRATION OF ISLAND AXIS, MIYEAR
37-M + CHESAPEAKE +
SAY LATITUDE -8 -4 0 4 8 -8 -4 0 4
CAPE HENRY 36'55

VIRGINIA BEACH so,
NORFOLK RUDEE INL E r
W45

BA K 40
BAY
@Q RGINIA _ 35
36-30 + NORTH CAROLINA 36*30

25'
COROLLA
20

36-15

DUCK 10

KITTY HAWK 05
SOUND CROATAN SHORES
Zoo AL ,,,RLE WILL DEVIL HILLS1 36*00
NAGSHEAO
10 Ss
N
BODIE IS
WAN 'SE
I' OREGONMLET
PEA IS 35-45

SCALE 40
20 10 0 n 40 KM ROOANTHE 36
IIIIIIIIEZ01:30009=301111101=1 WAVES
SALVO
35-30 + 35*30

AVON 20
rTERAS IS
11100CO HATMTEARAS OUXTON 35*15*
CAPE HATTERAS 1852-1917 1917-1980
HATTERASIMLET
OCRACOKE IS.
SURVEY PERIOD

OC ACOKE
35-00 + + INLET +
Figure 50. Rates of position change of island axis, 1852-1917 and 1917-1980,
between Kitty Hawk and Cape Hatteras, N. C. (island axis = midpoint between
77@

ocean and sound shoreline)

c. Island narrowing south of Oregon Inlet (Figure 47) generally
occurred as a result of combined ocean and sound shore retreat
(Figures 28 and 34).
d. Island width changes varied greatly in time in both magnitude
and direction (Figure 48). The period 1852-1917 was one of
slightly greater island widening; between 1917 and 1980,
island narrowing predominated.
e. Island axis migration rates (Figure 49) may be positive
(seaward-moving) in Back Bay but, because island narrowing
along both shorelines predominated here (Figure 47), to con-
sider this axis migration as island migration is misleading.
It is best thought of as island narrowing, with retreat of the
sound shoreline greater than the ocean shoreline.
f. Changes directly north and south or Oregon Inlet are the result
of inlet processes: the ocean shoreline has retreated and the
sound shoreline has prograded (Figures 28 and 34). Processes
associated with Oregon Inlet and New Inlet (Figure 9) are
responsible.
g. Island migration was similar in direction for the 1852-1917 and
1917-1980 survey periods, with one exception (Figure 50): the
island axis in the.region centered on Avon, North Carolina,
moved seaward in the'former period and toward the mainland in
the latter period. This change in direction is primarily the
result of a shifting ocean shoreline (Figure 28).

PART V: PREDICTION OF FUTURE SHORELINE CHANGES

95. The NOS shoreline change maps show what happened between Cape Henry
and Cape Hatteras from 1850 to 1980. An analysis of the maps quantifies the
changes both spatially and temporally. Data regarding historical shoreline
changes can provide useful information with whi@h to predict future changes.
When the causes of change are imperfectly known, however, it is difficult to
predict future changes by extrapolating past trends because the future may
not mimic the past. It is not apparent from the results of this study that
the magnitude of future changes in shoreline behavior can be forecast. How-
ever, future changes at specific sites can probably be estimated for any given
time period relative to the average changes which have occurred in the rest of
the study area. This section treats these aspects of shoreline change pre-
diction separately.

Temporal Predictions

96. Great variability was found in change rates within the 1850-1980
survey period. It is not unreasonable to assume future changes will be dif-
ferent from the 1850-1980 average. The survey record of shoreline changes in
the study area is relatively short, intermittant, and nonuniform in frequency;
it also lacks noticeable trends through time (Tables 11 and 12, and Figures 45
and 46). Consequently, there is limited shoreline change data available with
which to extrapolate shoreline changes into the future. In addition, because
of the multiplicity of processes involved, it is impossible to evaluate the
relative importance of man's impact relative to changes in the natural pro-
cesses that caused the shore to accrete or erode.

Spatial Predictions

97. Many changes in shoreline position are likely related to local
conditions. Because wave, wind, and current data are unavailable over the
130-year survey period and throughout the study reach, a direct causal rela-
tionship cannot be established to predict those changes. However, most of the
alongshore variations in shoreline change appear to be influenced by the prox-
imity of the shoreline to inlets, capes, and nearby shore-connected ridges

(Figure 51). The relationship between shoreline change and these features
appears reasonable and informative, but the relationship does not consider the
actual processes causing the changes. Extrapolation of future shoreline
changes using both past shoreline change data and the relationships between
those changes and local features improves the forecasts, but even these pre-
dictions must be treated with caution. Clearly, an effort to establish the
causes of the shoreline changes related to local features is warrented.
Barrier island migration and narrowing
98. Barrier islands along the mid-Atlantic coast very likely formed on
the Continental Shelf considerably east of their present positions during a
period when sea level was much lower than it is today (Swift et al. 1972).
As sea level rose, the islands are thought to have migrated toward the con-
tinental land mass--or west in the study area. For this migration to have oc-
curred, the ocean side of the islands must have retreated and the sound side
must have prograded. During migration the islands likely had alternating
periods of net island narrowing and widening superimposed on the longer term
landward migration. Conditions favoring island migration are those that move
sand from the ocean side of the islands to the sound side. In the study area,
this would mean one or more of the following conditions:
a. Overwash transport. The optimum conditions are a narrow island
T-probably less than I km in width, and maybe quite a bit less);
a low island where dunes are absent, or low and discontinuous;
minimum vegetation, especially those shrubs and trees that
would hinder overwash; and storm surges of long duration in
which the water level exceeds the island elevation.
b. Aeolian transport. The optimum condition is a strong onshore
wind that exceeds 25 km/hour (that necessary for sand transport)
for long periods of time; a wide, dry beach area that serves as
a source for wind-carried sand; and an absence of vegetation so
that the windblown sand can be carried to the sound side of
the island. (A low, narrow island would probably allow a more
speedy trip for a sand grain from ocean to sound but is not
necessary for effective aeolian sand transport.)
c. Inlet-related transport. Most important to island migration is
the presence of many large and relatively permanent inlets
which intercept sand moving in the littoral zone and move it
in a net westward direction. An inlet is capable of removing
a large portion of the sand moving in an alongshore direction
and transferring it to shoals in the sound or to the sound
shoreline adjacent to the inlet. As the number, size, and
persistence of the inlets increase, the amount of sand moved
in a landward direction increases and the probability of island
migration increases.

OCEAN SHORELINE CHANGE, ABOUT 1850-1980, MIYEAR

-5 -4 -3 -2 -1 0 1 2

37'00 + CHESAPEAKE +
DAY CAPE HENRY LATITUDE
36'65' @@Z= -77-
VIRGINIA BEACH 50
NORFOLK RUDEEINLET CAPE HENRY

36-45
@7
_W7
BA K 40
SAY
35 FALSE CAPE SHOAL
C%2
36 30 NORTH CAROLINA 36*30 LEGEND.
E3 CAPEINFLUENCE
25 EM SHOREFACE - CONNECTED RIDGE
COROLLA INFLUENCE
= INLETINFLUENCE
20
0
INFERRED BOUNDARIES
SITE OF RIDGE INTERSECTION WITH
7-
SHOREFACE
DUCK 10

KITTY HAWK 05
SOUND CAOATAN SHORES
36-00 ALBEMARLE WILL DEVIL HILLS) 36-00 -.r
NAGS HEAD
5, OREGON SHOAL
60DIE IS 44
ANC"ESE
OREGONINLEr
0 OREGON INLET
35'4S
PEAIS

SCALE 40
20 10 0 20 40 KM RODANTHE 35
WAVES
SALVO WIMBLE SHOAL
35'30 + 35'30

25 KINEKEET SHOAL
101, AVON 20 . .....
HArr RAS IS BUXTON CAPE HATTERAS
HATTERAS CAPE mA rTERAS 35*,5

HArTERASIAMET
OCRACOKE'S

OCRACOKE
35'00 + + INLET +

Figure 51. Relationship of apparent ocean shoreline change to capes, shoreface-
connected ridges (shoals), and Oregon Inlet

99. The data presented herein have shown that although islands in the
study area narrowed over the 130-year study period (Figures 47 and 48), they
did not migrate in the classic sense toward the mainland because both the

ocean and sound shorelines retreated toward the island. The reasons island

migration has ceased are not clear. Quite likely, overwash has not been an
important mechanism in sound shoreline progradation for the last several
hundred years. Today, the islands are probably too wide in most places for
overwash penetration across the entire island (Leatherman and Fisher 1976).
In addition, prior to about 1800 the islands were well vegetated with trees
.and shrubs (Hennigar 1979) which would have either inhibited overwash or been
destroyed had frequent or severe overwash conditions existed. In the nine-
teenth and early.twentieth centuries, aeolian transport may have been of some
local significance because poor land practices had left the island barren
(Hennigar 1979). However, at other times wind-transported sand probably did
not account for much sound shoreline progradation. If island migration oc-
curred in the study area between 1585 and 1850, it was probably the result of
inlet processes. Figure 9 shows that the number and permanency of inlets have
decreased in the study area from 1585 to the present time; if migration is not
occurring today, it is probably because the impact of inlets is too small.
Only Oregon Inlet now acts as a sediment trap in the study area; significantly,
the barriers adjacent to it are migrating in a westerly direction.
100. The reasons for island narrowing are also not clear; nor is it
clear when the narrowing cycle began or when it will end. Sand losses from
the front and back of the islands in the recent past may have been partially
caused by a rise of sea level relative to land--a vertical rise of probably
4 mm/year in the study area since 1930.(Hicks 1981) (on a static shore slope
of 1:40, for example, this would translate to an apparent shore retreat of
0.1 m/year). Quite likely a relative sea level rise would also have caused
dynamic changes in the beach that would-have increased the shore retreat rate;
this effect cannot be quantified at present. Long-term changes in wave and
wind conditions also could have forced the ocean and sound shores to retreat
or accrete, especially if the frequency and duration of storms had changed
substantially. An added factor, frequently not considered, is that unconsoli-
dated marine coasts may retreat under "normal" conditions. Whether the rate
of relative sea level rise will increase or decline and whether wind and wave
conditions will produce more or less erosion in the future are unknown.

101. Island narrowing must have begun before 1850. It will, of course,
end when the islands disappear or when one or both shorelines begin to pro-
grade. At the present average rate of island narrowing (0.9 m/year), it will
take almost 1700 years for a 1500-m-wide island to narrow to nothing. Before
that happens, though, overwash, if allowed, will likely begin to transport
sand to the sound shoreline and island migration will commence. A reasonable
forecast based on past behavior is that narrowing will probably continue in
the foreseeable future.
Alongshore sediment transport reversal
102. Waves approaching shore at acute angles and winds with a shore-
parallel component create alongshore currents. Sediment mobilized by wave
activity is moved by these currents. Over the period of a year the amount of
sand moved one way is rarely balanced by that which is moved the other way; the
difference is the net volume of littoral sand which moved preferentially in one
direction. This net volume and the direction it is moved may change from year
to year and over longer time periods as the wave and wind climate changes.
103. Study results tell us little about the net volume moved; however,
they provide some indication of the direction of net sediment transport. Other
studies have suggested that, on the long-term average, 2 X 10 5 cu m/year of
sediment moves north at Rudee Inlet* and 5 x 10 5 cu m/year moves south at Ore-
gon Inlet (U. S. Army Engineer District, Wilmington 1980). This net transport
indicates that a change in the net alongshore sediment transport direction--
i.e., a transport reversal--occurs somewhere between the two inlets. Evidence
from this study suggests that the reversal occurs near latitude 36'41' (Fig-
ure 28 shows a very uniform decrease in the shoreline retreat rate north and
south of that site (the north end of Back Bay)) to create a divergent long-
shore sediment transport nodal zone; i.e., a place where sand moves alongshore
to both the north and the south away from the site. Losses north and south
of latitude 36'41' are nearly equal and decrease progressively with distance.
Shoreline retreat rates are expected to decrease if a divergent nodal zone
exists because sediment moving away from the node will reach adjacent beaches
and thereby reduce the loss rates there.
104. The large shoal complex east of the Chesapeake Bay entrance

Personal Communication, James Melchor, 1991, Oceanographer, U. S. Army
Engineer District, Norfolk, Va.

influences the refraction path of waves approaching the coast from north to
east. The effect of the topographic high is to bend waves approaching from
north of shore-normal to approach from the south. This mechanism tends to
create a northward-directed current, which supports the inference that an
alongshore sediment transport nodal zone exists near latitude 36*41'.
105. At Rudee Inlet, the net alongshore transport rate of 2 x 10 5 cu M/
year based on recent dredging records, is 60 percent of an estimated
3.4 X 10 5 cu m/year cummulative volume loss north of the nodal zone. The
latter value is based on long-term shoreline change rates (Figures 28), the
alongshore distribution of those rates, and a 10-m shoreface depth (Haller-
meier 1977). Therefore, in recent times 60 percent of the sediments lost from
the beaches appear to have moved in an alongshore direction primarily inshore
of the ends of the Rudee Inlet jetties (Figure 24). Loss rates in the nodal
zone area are based on 130 years' record and variations from one survey to the
next were small (Figure 29), indicating that conditions have not varied as
much there as elsewhere in the study area. Some of the unaccounted-for 40 per-
cent of lost sediment may have been moved west by overwash or wind transport,
or east and offshore into water that is deeper than the jetty ends. In addi-
tion, the static effect of sea level rise relative to land at 0.4 mm/yr (Hicks
1981) on a beach sloping at 1:30 would be a yearly loss of 26,000 cu m, or
about 20 percent of the unaccounted-for sediment. Rising sea level may have
had an additional, unquantifiable effect on the dynamics of the system.
Sound shoreline change
106. Dune construction, either by natural or artificial means, is
usually accomplished at the expense of sand in the littoral zone. To compen-
sate for the lost sand, the shoreface and beach profile, and, consequently,
the shoreline, will retreat. This was probably the case following construc-
tion of the continuous dune between South Nags Head and Cape Hatteras which
was begun artificially, using sand fences, between 1936 and 1940. Dune pro-
file data and rates at which the dune grew are unavailable; however, if a
final 5-m-high-by-60-m-wide dune with about a 3-m-high overwash platform re-
sulted and a shoreface depth (i.e., the depth from mean sea level (MSL) to
base of shoreface) of 10 m is assumed, the removal of that volume of sand from
the littoral zone would result in a shoreline retreat of 11 m. Dune-building
may be a factor in the increased shore erosion between Oregon Inlet and Cape
Hatteras between 1917 and 1949 (Figure 45).

107. Driven by storm surges (Figure 15), overwash probably occurred
frequently in the study area before dune construction; however, it likely had
only a minor effect on the ocean and sound shorelines (Figures 52 and 53).
Shoreline position changes do not seem to be related to island width for either
the ocean or sound shorelines, except near existing or recently closed inlets.
Away from inlets, the sound shoreline where the island was less than 900 m
wide retreated at an average rate of 0.6 m/year (Figure 53), which is greater
than the average retreat rate for island sections where the width was greater.
Accordingly, overwash probably did not significantly affect the sound shore-
line during the period from 1850 to 1980. If the effect were important, the
sound shoreline at narrow places on the island would have likely prograded as
sand moved from the beaches into the sound.
108. Away from inlets, the retreat of the sound shoreline can be ac-
counted for mostly by sea level rise. At an average surface gradient of 1:100
near the sound shoreline, and a sea level rise of 0.004 m/year (Hicks 1981),
the sound shoreline retreat rate would be 0.4 m/year, or nearly the actual
rate measured. This rate will vary in the future as the sea level change

rate relative to the island varies.

LEGEND

z cr2 *OPEN N-S FACING COAST
W W 8 NEAR PASTOR PRESENT
U @: INLET
0
0
z
<

0
Ui 41
z0
<
4 016
W *0
z M

0 LU
z cr
< 0
z U)
< z
2 LU 2 -0

-3M
500 1000 1500 2000 2500 3000 3500 4000 4500
ISLAND WIDTH, M

Figure 52. Ocean shoreline changes from about 1850 to 1980, Cape Henry
to Cape Hatteras, as a function of island width in 1980 (shoreline
changes are shown in Figure 28)

m 0) rt W W 0 0-3 rD Fl- 0 m @o ct
pi 1:71 o r_ H. 0 0) t-b 0 " " " ;:r
0 0 IV- " " 0 D) C-) @71
cn r_ @_a (D ct IT 0 En re w m H.
H. ct (D Q rD 0 0 r_r @r r) rb L@. ct OIQ
0 ft 1.4 H. Ct (D M ct (A CA @:;'0 W z
00 co H. 0 N (a Ct A) C) P1
H. O@ rt* I,-j - 0 En C) n o m .4 %@o 0) CD
0) IT 0 Ct I::r. En (D
rt 0 ct Ow
co 0 @o
0 C) :31 rD rt 0@ 010 0 03 10 m (D
0 tl M 10 P @3' L- m 0 " :3" TO MAINLAND
ol rD " rD 0) OQ w W m H. M, 0 r_ rt 1_@ 0 0) MEAN SHORELIN
m m W. m CL rt. 0 r) " En H- Z5 :c < " (D " CA cn
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t"I al CL H- El N 0 rb P, & :e iI
0 fD " 0 t:r IT p w rD m 0 H.
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191, m kel ul 9 W (D H-
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P- M, Fl- In r+ 4) H. 0) w 0 m
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M I-h - Id r+ m J=. OQ m rD
m IT 0 1:r m 0 IT F- En Ch IT W
H. C+ " 0. 1-- 0 (D M 0 w =
r) = H. r+ @o CA r+ r+ w
r_Tl IT 0 P, H. IT 0
0. (D ::$

inlet increases. (The past site of New Inlet (Figure 9), just north of
Rodanthe, also has experienced major erosion since 1850 (Figure 31).) The
sound shoreline has been affected to a lesser extent (Figures 34 and 36), but
the net change has been one of progradation. This shoreline adjustment adja-
cent to Oregon Inlet is related to the normal alongshore sediment transport
(see paragraph 103) of beach sand. When this sand reaches the inlet throat,
some is carried landward by flood-tidal currents and deposited within the in-
let system. The large shoal area in Pamlico Sound west of the throat at Oregon
Inlet is evidence of that inlet's trapping capacity. The sand composing those
shoals is coarser than the sound sands upon which the shoal area rests. In-
lets such as Oregon Inlet probably trap sand until the sound shoals have grown
to attain a quasi-equilibrium condition, at which time the volume of beach
sand which enters the inlet on a flood tide is balanced by the volume carried
out on the subsequent ebb tide. The trapping rate of an inlet normally de-
creases with time after the inlet opens. However, when an inlet moves paral-
lel to shore as Oregon Inlet has done (29 m/year on the average, Figure 38)
the entrapment rate may not decrease very rapidly because the flood-tidal
shoals never attain a quasi-equilibrium state of development.
112. An analysis of Oregon Inlet sand gains relative to adjacent ocean
shore sand losses provides an approximate means to illustrate that most of
the adjacent shoreline retreat is inlet-caused. Approximately 32,000 sq m/
year (4.2 X 106 sq m, total) of barrier island surface area has been lost
since 1849 within 8 km of Oregon Inlet (Figure 40) (to some extent, these
values have also been influenced by previously open New Inlet (Figure 9)).
To calculate the volume of sand moved, the depth to which the shoreface
profile has been modified must be considered; a reasonable depth (Hallermeier
1977) is about 10 m. Using the surface area lost (Figure 40) and the assumed
10-m depth to which erosion occurred, approximately 4 X 10 7 cu m of sediment
was lost from the barrier islands adjacent to Oregon Inlet between 1852 and
1980. The ebb- and flood-tide shoals in Oregon Inlet cover an estimated
2.5 x 107 sq m of Pamlico Sound. At an average estimated thickness of 2 m,
7
these inlet deposits contain 5 x 10, cu m of sands transported from the ad-
jacent islands. Thus, according to this very crude analysis, the sands lost
from the beaches near Oregon Inlet can be accounted for within the inlet sys-
tem, primarily in Pamlico Sound flood-tide deposits. Of course, superimposed
on the inlet-caused ocean shoreline change, is the long-term 0.8-m/year

100

retreat which exists for the entire study reach.
113. It is interesting to note that the sand entrapment rate has re-
mained relatively constant since 1849 (Figure 40). The only perturbation
occurred during the 1949-1963 period when the March storm of 1962 greatly
changed the inlet (Figures 38, 39, and 40). Poststorm recovery, however, re-
turned the system to its prestorm condition; Oregon Inlet is apparently still
trapping sand (1980) at about the rate it trapped it in the first 66 years
after it opened. As long as Oregon Inlet remains open and unstructured and
continues to migrate south, the sand entrapment rate should remain near its
1852-1980 average value of 3 X 105 cu m/year. Adjacent ocean shoreline be-
havior should remain similar to that shown in Figure 28. As the inlet mi-
grates south, the inlet-influenced ocean shoreline 8 km north and south of
the throat also will migrate south.
114. Small, structured Rudee Inlet is presently not acting as a sand
trap; littoral sand that is moved into the inlet throat is returned to Vir-
ginia Beach by hydraulic means. In the future this inlet will not likely
affect adjacent beaches as long as present (1980) conditions prevail.
115. Past inlets. Inlets have been located, in historic times, in two
regions: in northern Currituck Sound and centered around Oregon Inlet (Fig-
ure 9). Probably the largest prehistoric inlet (pre-1585), as evidenced
primarily by beach ridges, was located at Kitty Hawk, North Carolina (Fig-
ure 11). Small ephemeral inlets have been opened during storms, but natural
movements of sand along the coast have caused them to close within a few years.
Only relatively stable passages through the barrier spits and islands are in-
cluded in Figure 9.
116. Sands are deposited in flood-tidal shoals within the sound, on
adjacent sound shorelines, and in ebb-tidal shoals in the ocean after an inlet
opens. The net sand loss from adjacent beaches is reflected in an increase
in the rate of ocean shoreline recession. Conversely, the sound at the inlet
gains sand. If the inlet subsequently closes, the flood-tidal shoals fre-
quently form a new shoreline or islands in the sound (Figure 37). Inlet
closure is usually accompanied by ocean shoreline readjustment such that is-
land width at the site of the former inlet increases; i.e., the ocean shore-

line builds seaward.
117. An anomalously wide portion of a barrier island is often a clue to
the previous existence of an inlet. In Figure 11, which plots island width

101

with inlet location and the length of time the inlet was open, the anomalous
island widths shown near latitudes 36'15' and 36100' most likely reflect pre-
1585 inlets. The existence of these sites indicates that the islands have
existed in or near their present locations for at least the past 400 years.
118. Wide portions of barrier islands are usually less susceptable to
a new inlet opening than are narrow portions. Thus, while the existence of
an anomalously wide island reach often reflects the past site of an inlet, it
probably is not a prime site where a new inlet will open. However, ocean and
sound hydraulic characteristics, which were once maximized at the previous
inlet location, probably did not change much; therefore, that general region
remains a potential site for a new inlet. These sites can be identified in
Figure 11.
119. Inlet effects on the ocean coast are rapidly muted after the inlet
closes. Within a decade after closure, the effect of an inlet on the adjacent
shorelines is no longer noticeable (see New Inlet, for example, in Figure 37).
This occurs because alongshore sediment transport and the landward transport
of ebb-tidal shoal material act to straighten the ocean side of the previously
inward-flaired coast.
120. Conversely, the effects of an inlet on the sound shoreline may per-
sist for hundreds of years (see Kitty Hawk Inlet, for example, in Figure 11).
In the years after the inlet closes, the flood-tidal shoals may become islands,
or may weld to the adjacent sound shores and spread and become less pronounced

with time.
Capes and shoreline change
121. Cape influence is reflected in the behavior of adjacent ocean
beaches. It appears that changes in the east-facing ocean shoreline at least
14 km south of Cape Henry and 10 km north of Cape Hatteras are dominated by
the respective capes (Figures 28 and 31).
122. At Cape Henry the east-facing shoreline prograded while the nearby
north-facing shoreline retreated (Figure 44), a situation that will likely
continue into the future. The progradation could increase if additional arti-
ficial beach fill is placed on Virginia Beach. Some of the recently placed
fill material moved north and was deposited along the east-facing shoreline
(Figure 28).
123. The position of Cape Point at Cape Hatteras is highly variable
(Figure 41), and its year-to-year movements do not appear to be predictable.

102

In general, though, the longer trend term appears to be to the south and west),
as reflected in changes on the nearby shoreline (Figure 28). North of the
cape, the shoreline movement has been one of retreat to the west, with the
greatest westward retreat nearest the cape. West of the cape, the shoreline
has prograded; this movement has occurred for a long time and is referenced in
a large number of east-west-trending ridges. Future shoreline changes north
and west of Cape Hatteras will likely be similar to those that have occurred

in the past.

Shoreface-connected
ridges and shoreline change
124. Shoreface-connected ridges also appear to significantly influence
the ocean shoreline in the study area. These linear ridges with a maximum of
10-m relief extend up to 10 km offshore from the shoreface in a northeast
direction; side slopes are usually not more than a few degrees. Fields of
such ridges are common from Long Island to Florida (Swift et al. 1972). Loca-
tions of the four shoreface-connected ridges along the east-facing ocean in
the study area are shown in Figure 54 and listed in the tabulation below.

Name Latitude
False Cape Shoal 36033'
Oregon Shoal 35052'
Wimble Shoal 35033'
Kinekeet Shoal 35023'

125. The ridges intersect the shoreface about 5 km south of some of the
most prominant concave seaward shorelines in the study area (Figure 55).
Except at inlets, these are the major sites along the east-facing ocean reach
where the shore orientation varies greatly. The shoreline at and south of the
ridge intersection is generally convex in a seaward direction. In all cases
the site of the intersection is along a reach where the shoreline is rapidly
changing from a northwesterly to a northerly direction.
126. Shoreline changes associated with the shoreface-connected ridges
are predictable. Shorelines north of ridge intersections retreated, while
those to the south usually prograded. One exception is south of Oregon Shoal
where the shoreline retreated, probably because of the influence of Oregon
Inlet. Shoreline changes adjacent to the ridge intersections appear to vary
with time in a relatively consistent manner. Data shown in Figures 30 and 31
suggest the ridge influence is moving south.

103

SHORELINE IN FEET

0Z 1@
0
9
_77

LONGITUDE
76-07

37-00- + CHESAPEAKE 7059 m
DAY LATITUDE
"PENENRY

VIRGINIA ISFAC. NOS 11555
RuDEEI.IE,
ORFOLK DEC 6 .1980
Ww

Q
RA K
@QRGINIA_ 35
M'30'+ NORTH CAROLINA X*30

25 at
WROLLA

WIS

K 10

KITTY HAWK 05
0 CROA AN SHORES
Zoo "06NIA"I (KILL DEVIL HILLS) Woo
1ASSMIA" NOS 12204
65
N E FEB 21,1981
Bo.IE IS -4.
IRA ESE SO
OREGONINLET
m. Is 35-45

SCALE
20 Io o n 10KM RMANTHE 35 C==:b
WAVES RIMS,
"LVO
@@-3. + 35-30

AVON
m
11E.AS IS BUXTON v
-AS CA-YERAS WIS

AS
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35-00 + AWKE NOS 1155 m
+ '.LEI + DEC 6,19850

Figure 54. Bathymetry seaward of the ocean shore between Cape Henry and Cape Hatteras (the
shore-normal scale is greatly exaggerated to show the alongshore variability in bathymetry;
arrows identify sites where northeast-trending ridges intersect the shoreface)

SHORELINE ORIENTATION
(TRUE NORTH = 0)
37-00' + CHESAPEAKE +
BAY LATITUDE 30e 3150 3250 335' 3450 35e 0050 Ole
CAPE HENRY 36,55,

VIRGINIA REACH 50'
NORFOLK RUDEEMET
-A 36'45'

7- 40'
8A CK
BAY
35'
RGIN12@ _
36-30' + NORTH CAROLINA 36*30'

25'
COROLLA
20'

0
DUCK 10'

KITTY HAWK 05'
SOUND CROATAN SHORES
36-00" ALOEM,RLE (KILL DEVIL HILLS) 36*00'
NAGSHEAD
0 55'
C> N E
k SOME IS.
WANCHESE 50'
OREGONINLEr
35-45'
PEA IS.

40'
SCALE
20 10 0 20 40 KM RODANTHE 35'
=3011111111=1 WAVES
SALVO
35-30- + 35*30'

25'

AVON 70'
HATTERAS IS,
""40 CO BUXTON 35*15,
HATTERAS CAPE HATTERAS

RATTERASINLET
OCRACOKE IS-,A

OCRACOKE
35'00 + + INLET +
Figure 55. Shoreline orientation referenced to true north between Cape Henry and Cape Hatteras
(arrows identify sites where northeast-trending ridges intersect the shoreface)

PART VI: SUMMARY AND CONCLUSIONS

127. Shoreline change maps of the ocean and sound shorelines from west
of Cape Henry to west of Cape Hatteras were produced using historic NOS shore-
line maps. The accuracy of the shoreline change maps is estimated to be at
least within �10 m. Using a digitizing procedure, average shoreline change
rates were quantified for 2-km-long reaches of the study coast. Predicting
the magnitude of shoreline change rates for future years is difficult because
of undefined temporal changes in the processes which produce the changes.
Relative shoreline change rates, however, can be forecast with some confidence
in an alongshore direction; that is, the relative rates at adjacent shore
locations can be forecast based on relationships with geomorphic features at
or near the locations. The following characteristics of shoreline change in
the study area can be concluded from this study:
a. Shoreline change rates have varied greatly from one time period
to another (Tables 11, 12). Because of these variations and
the difficulties encountered in attempting to account for them,
accurate quantitative forecasts of the absolute magnitude of
shoreline change decades into the future are not possible using
data acquired in this study. However, very likely the general
erosional trend which existed between 1850 to 1980 will
continue.
b. Barrier spits and islands generally narrowed between about 1850
and 1980. This narrowing contrasts with geological evidence
that the barriers have migrated landward in the past thousands
of years. Island migration, in the classic sense, is ocean
shore retreat and simultaneous sound shore progradation; i.e.,
island movement toward the continental landmass. Island nar-
rowing in the 130-year study period may be a higher frequency
trend within the longer term trend of island migration which
occurs in association with sea level rise relative to land.
c. The barrier islands appear to be too wide (1980) to migrate as
the result of overwash processes. Overwash-transported beach
sands rarely reach the sound side of the islands.
d. Island width (Figure 12) correlates well with two inlet systems
that existed before 1585 (geomorphic evidence) and inlets that
existed after 1585 (evidence in maps and charts).
e. Inlets in the study area have tended to open and close in
specific regions, but not in the same places in these regions.
Because inlets often (but not always) caused the island to
widen after the inlet closed, the historic inlet area became
less susceptible as a site for a new inlet. But because the
hydraulic characteristics of the ocean and sound caused the
region to remain susceptible as a new inlet site, new inlets

106

tended to opennear the sites of past inlets. Sites where
inlets existed in the past 400 years (see Figure 9) are
(1) Nags Head to Rodanthe and (2) Duck, North Carolina, to
the Virginia State line.
f. Oregon Inlet, the only unstructured inlet that has been open
in the study area for the entire study period, apparently af-
fected the ocean coastline at least 8 km north and probably
8 km south of its 1980 location (Figure 37). Shoreline changes
to the south were masked by the opening and closing of New
Inlet. Shore erosion decreased exponentially away from the
inlet (Figure 28). A rough calculation of ocean shoreline
losses and Pamlico Sound sand gains indicates that nearly all
the Atlantic Ocean sand lost from 8 km north and south of the
inlet was deposited in Pamlico Sound. This net movement of
sand in a westerly direction could, on a time scale of hundreds
or thousands of years, be a major factor in island migration.
Today, inlet processes are the major mechanism for moving lit-
toral sand in a westward direction. Wind is probably second in
importance.
Because of near-continuous southward migration of Oregon Inlet
(about 29 m/year), the amount of littoral sand trapped in the
flood-tidal shoals of Pamlico Sound appears to have been con-
stant through time (about 3 x 10 cu m/year (Figure 40)).
h. Evidence of inlets that closed before 1585, most notably at
Kitty Hawk, suggests the islands have not moved appreciably
(i.e., not more than one-fourth the island width) in at least
the past 400 years (Figure 12).
i. Capes affect adjacent beaches. In the past 130 years, the
east-facing beach south of Cape Henry accreted, while the east-
facing beach north of Cape Hatteras eroded (Figure 28). Con-
currently, the north-facing beach west of Cape Henry eroded
and the south-facing beach west of Cape Hatteras accreted. The
net change is a very slight clockwise rotation and southward
movement of the cape boundaries. The eastward progradation of
Cape Henry and the southward progradation of Cape Hatteras are
similar to longer term geologic changes in these areas as re-
flected in the orientation of beach ridges (Figures 2 and 7).
Erosion north of Cape Henry and north of Cape Hatteras does not
reflect past geologic changes; however, because these changes
have occurred for at least 130 years, they can be expected to
continue into the future.
A divergent alongshore transport nodal zone, identified using
shoreline change data, exists near latitude 36*41'. This ap-
pears to be the only site of net alongshore sediment transport
reversal along the east-facing ocean coast between Capes Henry
and Hatteras.
k. Overwash probably has not been a major factor in producing
changes in the sound shoreline. Most of the retreat in the
sounds away from inlet influences can be accounted for by
considering sea level rise on a gently sloping shore.

107

1. Shoreface-connected ridges intersect the ocean coast at four
places. In each location, the shoreline north of the ridge
intersection retreated, while the shoreline prograded south of
the intersection. The ridge intersections are about 5 km south
of the most prominent concave shore reaches (Figure 55) away
from inlets. At and south of the ridge intersections, the
shoreline changes rapidly from a northwesterly to a northerly
orientation.
m. Characteristics of the shoreface-connected ridges are not
dependent upon the net alongshore sediment transport direction.
The False Cape Shoal is near a transport reversal; other ridges
are located in areas where the net transport is to the south.

108

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