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Physical Environments
INTRODUCTION
Physical Geography
North Carolina’s physical environment varies over the state.
In part, it is this diversity that makes the state’s geography interesting. To understand North Carolina’s people and environments
a geographic appraisal of its physical environments is necessary. What then is physical geography and what is meant by a
geographic appraisal? Geography is comprised of three branches,
physical, cultural, and regional. Within each of these branches
are many component parts. In physical geography these parts
include water (hydrology, oceanography), animal and plant life
(zoogeography, biogeography), soils (soil science), rocks (geology), landforms (geomorphology), and weather and climate (meteorology, climatology). Physical geography is not just the study
of these individual elements of the physical environment. It is
the interaction of each with one another and with people. Physical geography helps to specify these relationships, and it emphasizes the “spatial” aspects of the relationships. This spatial
component allows us to view and comprehend the patterns that
comprise the earth’s surface. Geographers create and use maps
as the ‘tool’ to achieve this (through the art and science of cartography). Throughout this book there is extensive use of maps
and graphics to help in viewing and analyzing the geographic
perspectives of North Carolina. The science of geography provides understandings of the cause and effect of these elements
and the processes that create the spatial patterns. The physical
section (Chapters 1, 2 and 3) introduces the important elements
of North Carolina’s physical geography.
Figure 1.1: Physical Setting - Vertical Sections.
Atmosphere
The atmosphere includes the “life-supporting” layer of air;
its lowest level to about ten miles is known as the troposphere. It
is within this zone that weather conditions occur. The atmosphere,
particularly the troposphere, provides a most important natural
resource: climate and its short-term character, weather. Most of
North Carolina is situated in the climate region known as Humid Subtropical, although there are many variations of this
throughout the state. Moisture is adequate throughout the year
and is capable of supporting dense forests as well as a great
variety of agricultural crops with only limited or localized irrigation or drainage needs. Temperatures are moderate with long
summers and brief winters. Snow does occur throughout the state,
but the mountains receive the steadiest supply throughout the
winter months. Air masses accounting for this climate (Figure
1.2) are controlled by a variety of phenomena such as latitude,
Environmental Systems
Consideration of the physical setting requires discussion
of the systems involved. Here is illustrated the three parts of our
environment that involve and impact people (Figure 1.1). These
parts of the physical setting are atmosphere, bio-hydrosphere,
and lithosphere. We will look in some detail at how each contributes to the total physical environment, we will assess their
implications for the people who live in the bio-hydrosphere, and
we will define the impacts on the atmosphere and lithosphere
across the state.
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elevation, mountains, land cover characteristics, land and water
surface differences, and more recently the possible impacts of
‘el nino’ and ‘la nina’.
in the state are also an essential component of the physical environment. While the state receives an average annual precipitation of 122 centimeters (48 inches), precipitation ranges from
97 (38 inches) to just over 154 centimeters (100 inches). It is
also important to note these variations and diversity throughout
the state also characterize the systems that carry and deliver this
water. These systems are discussed later in this chapter, as well
as in Chapter 2.
Lithosphere
The lithosphere consists of surface materials and their formations downward to about 40 to 80 kilometers below the earth’s
surface. It is generally thought of as comprising not just the minerals and rocks but also the land surface, soils, and groundwater.
Resources provided in the lithosphere are the foundation for
vegetative growth, natural and managed, and some economic
activities such as mining and energy production. Soils also take
on new functions as areas are settled or urbanized. Soils not
only produce trees and food, but also handle waste and construction, with their properties becoming increasingly important
considerations. Soils are a complex mix of minerals derived from
parent rock, organic matter from plant and animal life, water,
and air. As a consequence, soils vary greatly according to rock
type, climate, natural vegetation, location, elevation, degree of
slope, solar orientation, and age. The coupling of these characteristics configure the land surface. Land surface is a product of
the rock types and their associated tectonics or movement, as
well as the erosional and depositional processes acting on them.
Analyzing land surface form includes consideration of slope,
local relief or changes in elevation, and profile type in addition
to prominent ridgelines and summits, escarpments, water features, and sandy areas.
Figure 1.2: Air Mass Origins and General Circulation Patterns.
Bio-hydrosphere
The bio-hydrosphere is the thin layer where living organisms and water co-exist on the earth’s surface. This includes the
life layer of plants and animals as well as the surface waters that
support this life and also modify the landscape. North Carolina’s
most dominant landscape characteristic is forest cover (Figure
1.3). The mountain and coastal regions include 26 counties having greater than 65% or more of their land in trees, while the
Piedmont region has been modified heavily by human activities. A wide variety of human activity, in the Coastal Plains and
Piedmont, has modified much of the vegetative cover through
the management of pine forests for their commercial value. One
thing is certain; this state exhibits great diversity from the western reaches of a Smoky Mountain valley to the eastern most
edge of an exposed sand dune of a barrier island. Water resources
PHYSICAL SETTING
World and Regional Context
Spatial Expanse
The location of North Carolina on the earth has impacts
on its physical environment. It is in the Western Hemisphere on
the North American continent, and it is within the political jurisdiction of the United States of America. Within this context it
has an East Coast setting that is centrally located between the
states of Maine and Florida. North Carolina’s norther- most border is 36°30’ North Latitude while its southern-most extent is
around 33°50’ North Latitude. Its eastern-most edge is situated
about the 75°20’ West Longitude and the western extent reaches
84°25’ West Longitude.
Comparatively speaking the state has a vast east to west
expanse, as it is over 805 km (500 mi) wide. Its north to south
expanse is not nearly as great, varying from 322 km (200 mi) in
the eastern parts to 161 km (100 mi) in the west-central section
to less than 40 km (25 mi) in the western most part. North Caro-
Figure 1.3: Forest Cover (percent by county).
Source: North Carolina Statistical Abstract 1994.
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lina has approximately 137,269 square kilometers (53,000 sq mi) of
land area. CP1.1 illustrates the setting in the world and southeastern United States and shows the state’s regions and counties. It is bordered to the north by Virginia, to the west by Tennessee, to the south by Georgia and South Carolina and to the
east by the Atlantic Ocean. North Carolina is easily recognized
by its long narrow form and the outer banks or barrier islands off
the coast. This spatial expanse also helps explain some of the
physical differences in the state.
degrees north latitude, which is representative of North Carolina’s
average latitudinal location), and a high latitude location. At each
of these locations note the total land area that the sun’s rays are
concentrated on. The angle at which the sun’s rays strike the
surface is referred to as the angle of incidence. At North
Carolina’s average latitudinal location the noon angle of incidence varies from about 78 degrees for summer to 31 degrees
for winter, and causes marked seasonal differences in the amount
and intensity of solar energy received and thus the average air
temperature.
In addition to the solar angle, the length of daylight also
influences air temperature. Hours of daylight received at the latitude of North Carolina vary from a maximum of 14.5 during
summer to a minimum of 9.5 during winter. Temperature differences are further complicated by the mountain environments in
the western part of the state (this particular aspect is explained
Geologic Activity
The theory of plate tectonics describes the earth’s plates
and their past and present interactions or movements and has
influenced many aspects of geology. Tectonic activity is directly
related to location on a plate. Around the edges of the plates is
where the most violent activity occurs. North Carolina is centrally located on the North American plate. This does not mean
that there is no tectonic activity. On the contrary, there are fault
lines and earthquakes although currently there is little or no activity with critical impacts. However, we do know that there
have been major geologic events that have affected this slice of
the earth, such as the creation of the Appalachian Mountains
and the uplifting of the Carolina coastal area. Box 1A illustrates
recent geologic activity in the Carolinas.
The state is bordered by the Appalachian Mountains to
the west and by the Atlantic Ocean to the east. Its elevation varies from sea level on the eastern most edges of the state to 2037
meters (6,684 ft) at the peak of Mount Mitchell in Mitchell
County (CP 1.2), highest peak in the eastern United States.
Weather and Climate
In this section we set the stage for understanding the basic
elements of climate and weather. Weather and climate, critical
aspects of our physical environment, are treated in detail in Chapter 2.
Figure 1.4: Sun’s Noon Angles. Varying mid-day insolation intensity
is illustrated for three distinct latitudinal environments: equator,
mid-latitude, and high latitude.
Source: Modified from McKnight, 1997.
Sun Angles
Earth-sun relationships are a key component in creating
the varied environments of our planet, generating both daily (rotation) and seasonal (revolution) characteristics. The angle at
which solar energy strikes the earth’s surface varies with degree
of latitude and with time of year. Resulting daily and seasonal
rhythms in turn act as fundamental controls of air temperatures,
winds, ocean circulation, precipitation, and storms – all of which
taken together make up the earth’s varied climates (Strahler
1987).
The earth’s axis is tilted at 23.5 degrees from perpendicular. This means that the most direct rays, hence the strongest, of
solar radiation are between 23.5 degrees north and south of the
equator. Since North Carolina lies between 34 and 36.5 degrees
north latitude, the strongest rays strike on June 21 (also known
as the summer solstice). The weakest sun angle occurs on December 22 during the winter solstice. Figure 1.4 illustrates the
sun’s noon angle at the equator, a mid-latitude location (35.5
further in Chapter 2).
Atmospheric Heating and Air Masses
Solar radiation is the only important source of energy reaching the earth’s surface and atmosphere. Incoming solar radiation is referred to as insolation. Insolation has daily, as well as
seasonal, variations. Additionally, the heating and cooling of different surfaces also varies greatly. Variation of surface conditions causes differential heating and cooling. In other words, the
properties of different surfaces will dictate the rate at which surfaces heat and cool. For example, if the same amount of insolation is received by land and water surfaces, land will heat more
rapidly than water, and land will also reach a higher temperature
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Box 1A: Earthquakes.
Magnitude is a measurement of
the quantity of energy released by
an earthquake. It is measured by
the Richter Scale, developed in
1935 by Charles Richter. Scale
numbers range from 0 to 9 and
are logarithmic, with nature’s own
force setting the upper limit. On
the Richter Scale a magnitude of
5.3 represents a moderate earthquake, while a strong earthquake
might have a magnitude of 6.3.
Great earthquakes have a magnitude greater than 8.0.
On April 13, 1998, an earthquake that measured 3.9 in
magnitude shook the Piedmont. Its epicenter was 25 miles
north-northeast of Camden, South Carolina. Almost two
months later on June 4; another quake occurred had a
magnitude of 3.2. Its epicenter was 10 miles northwest of
Kannapolis, near Mooresville, and between 10 to 15 miles
under ground. We are not in California, but we are still
susceptible to geologic activity. Faults, which are deep
underground in the Carolinas, can produce these ‘minor’
quakes. Pressure builds up and after decades of silence is
released rapidly by the earth’s movement; this movement is
known as an earthquake. The figure above illustrates recent
quake activity. Predicting quakes within a specified time
period is difficult to impossible, but selecting locations of
the most likely area of occurrence is more realistic. Quakes
can create a lot of panic and fear because people in the
Carolinas are just not accustomed to dealing with them. There
were no reports of injuries or significant damage for the June
4 quake, but for a few seconds, it shook buildings, rattled
windows, and scared a lot of residents near Lake Norman
(Charlotte Observer 1998). Although it appears that we are
not in any present danger, scientists warn that there may be a
future quake with a magnitude of 6.0 or better on the East
Coast. The most likely epicenters, Charleston, South Carolina
and eastern Tennessee, are not in the state. However, they are
close enough that considerable damage could occur. Safety
precautions have been taken in the construction of Duke
Energy Corporation’s two nuclear facilities, McGuire Nuclear
Station near Lake Norman and the Catawba Nuclear Station,
to withstand such a quake.
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than water. However, land also loses heat rapidly while water will
maintain a more stable temperature. Surface differentials in turn
helps to generate the characteristics of the atmosphere above a
particular surface or region. Air above a large water body will
maintain its temperature and will also contain moisture placed
into the atmosphere through evaporation. Conversely, air above
a landmass will have little moisture present in it. Air masses are
then circulated or moved across the earth’s surface. North Carolina is affected by maritime tropical (warm and moist) air masses
formed over the Gulf of Mexico and the Atlantic Ocean. In addition, the state is impacted by continental polar air mass (dry
and cool in winter, but quite warm in summer) formed over the
continental interior region. Air masses, their origins, and global
circulation pattern help to generate our daily weather (Figure
1.2).
The atmosphere, especially in the lower level of the troposphere, defines a most important natural resource, climate,
and its short-term character, weather. North Carolina lies within
a general climate region known as Humid Subtropical. Through
our lifetime we don’t expect climate conditions to vary greatly,
but all of us are impacted daily by weather. As mentioned earlier, air masses accounting for climate are controlled by a variety of phenomena that impact global circulation patterns. All of
these phenomena make us aware that climate is an important
resource, and we are also fully aware of the devastating effects
it may have in influencing the weather of our daily lives. It influences the way in which we dress for the day, the way we
build our homes, where we choose to live in the state, and many
other facets. In most cases, we have adapted well to the limits of
our physical environment. But, no matter how well we do this,
nature reminds us periodically to respect its power. Localized
and widespread effects of hurricanes, tornadoes, floods, power
outages, and frost damage to crops are some of the problems
directly relating to the atmosphere which have implications on
human activities. More subtle problems involve the degradation
of air and water quality, long-term effects of vegetation modification, land surface changes, and hazardous waste disposal. All
of these are reminders of nature’s force.
ern most reaches of Cape Hatteras (CP 1.3) to its western most
border south of the Great Smoky Mountains (CP 1.4). Elevations range from sea level to peaks exceeding 1,829 meters (6,000
ft). Such a varied landscape makes it difficult to categorize and
characterize the state without considering the regional context
and its spatial variability.
Geographers recognize four primary regions within North
Carolina (Chapter 9). These are the Mountains, Piedmont, Coastal
Plain, and Tidewater regions (see CP 1.1). The number of counties associated with each region, amount of area (both land and
water) covered by each and the percent of the state each region
covers are illustrated in Table 1.1. Each primary region is endowed with suitable physical and cultural similarities to clearly
distinguish it from the others. Mapping data to discover the spatial patterns that emerge within the state is a common tool in
gaining a geographer’s view or “geographic perspective.” Comparing mapped variations within and between regions can often
help define areas of high or low concentrations or the setting of
a particular activity and the placing of it within the state’s spatial context. Throughout this text maps allow the reader to note
coincidences between and among different variables and to place
these within a regional context. Our four primary regions are
used extensively and an understanding of each of their component parts is needed.
Changes in the physical landscape are apparent as one
moves through the state. While they may not be as pronounced
from south to north as they are from east to west, these variations do impact people and their activities. Geographers are interested in why things occur where they do, and often answers
affecting people and their livelihood are found in the physical
geography of the state.
Lay of the Land
Among the important components that help create the
physical landscape are land cover (vegetation), elevation, slope,
aspect or direction of slope, soils, and geology. People and their
cultural activities have over the centuries modified these components, and thus shaped the complexities of the landscape mosaic that exists in North Carolina today.
Primary Regions
Geology
The flat surface of the coast contrasts greatly with the
mountains of the west. As noted earlier, North Carolina is a state
with diverse physical and cultural characteristics from the east-
Emerald was designated as the state’s precious stone in
1973 and granite, in 1979, was named as the state rock. Geogra-
Regions
Number of Counties Land Area (km. sq.) Land Area (mi. sq.) Percent of Total
Mountain
24
26,367
10,180
20.9
Piedmont
35
42,535
16,423
33.7
Coastal Plain
22
34,543
13,337
27.4
Tidewater
19
22,735
8,778
18.0
State Totals
100
126,180
48,817
100.0
Table 1.1: The State’s Primary Regions.
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spatial characteristics of the state’s 10 major geologic belts, and
descriptions and examples of each belt follows.
The Coastal Plain is comprised of marine sedimentary
rocks that gradually thicken toward the coast. It is the largest
geologic belt, covering about 45 percent of the state’s land area.
Sand and clay are the most common sediment types in this belt,
with a significant amount of limestone occurring in the southern
part of the Coastal Plain. Well drilling information provides a
valuable source of data of the depth and the spatial extent of this
belt. Near Aurora, in Beaufort County, phosphate mining is the
state’s most important mineral resource in terms of dollar value
(Photo 1.1). Phosphate is an important component in fertilizer.
Additionally, mining of industrial sand (for producing container
and flat glass) and ferrosilicon (which is used for filtration and
sandblasting) can be found in the Sand Hills (CP 1.5) (North
Carolina Geologic Survey, 1991).
The Eastern Slate Belt contains slightly metamorphosed
volcanic and sedimentary rocks similar to those of the Carolina
slate belt. Rocks are poorly exposed and partially covered by
Coastal Plain sediments. Metamorphic rocks, 500-600 millions
years old, are intruded by younger, 300 million years old, granitic bodies. Gold was once mined in the area, while crushed
stone, clay, sand, and gravel are still mined today (North Carolina Geologic Survey 1991).
Granite, gneiss, and schist comprise the geology of the
Raleigh Belt. Earlier this century a number of small building
stone quarries existed, but today crushed stone for construction
and road aggregate support the extraction industry of this belt
(North Carolina Geologic Survey 1991).
phers ask what caused these to be abundant and important resources of the state. Where do these resources exist, what is their
spatial extent, and are they coupled with other resources or economic activity within the state? The earth formed four and onehalf billion years ago. North Carolina, as we know it today, is
relatively young when thinking of it in the context of the age of
the earth. Three major classes of rock types common in the state
are igneous, metamorphic, and sedimentary. Figure 1.5 illustrates the generalized geologic structure with major fault lines
and the varying major classes of rock types. This begins our
basic understanding of the state’s geology.
North Carolina has a long and complex geologic history.
Periods of uplifting and subsidence, along with accompanying
erosion and deposition of materials have helped provide our
current geologic setting. Sea floor spreading has caused the North
American continental plate to shift westward from an original
position adjacent to North Africa and Western Europe. The many
parallel fault lines throughout the state mark places where stress
has been relieved. Pressure build up has caused a change or
metamorphism of some rock such as the belts of metasedimentary
rock, gneiss, schist, and Carolina slate in the Piedmont.
Geologic Belts
Understanding the state’s spatial and temporal geologic
relationships is essential. Areas of similar rock type and age, as
well as geologic history, provide a description of the states geologic belts. Figure 1.5 illustrates an increasing age and complexity of rock types from east to west. Figure 1.6 shows the
Figure 1.5: Rock Types and Faults.
Source: Modified from North Carolina Center of Geographic Information and Analysis, 1998.
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Figure 1.6: Major Geologic Belts.
Source: Modified from North Carolina Geologic Survey, 1991.
The Carolina Slate Belt consists of heated and deformed
volcanic and sedimentary rocks. It was the site of a series of
oceanic volcanic islands about 550-650 million years ago. Numerous abandoned gold mines dot the area, which reminds us
that North Carolina led the nation in gold production prior to the
1849 California Gold Rush. Because companies are still showing interest, gold mining continues to be a minor extractive industry in this belt. Mineral production includes crushed stone
for road aggregate and pyrophyllite for refractories, ceramics,
Triassic Basins are filled with sedimentary rocks that formed
about 100-190 million years ago. Streams carried mud, silt, sand,
and gravel from nearby highlands into rift valleys (similar to those
of Africa today). As can be seen in Figure 1.6, there are three
locations of these basins within the state. Two are located in the
eastern section, while the other is in the northwestern Piedmont
region. Mudstones are mined and processed to make brick, sewer
pipe, and structural and drain tile (North Carolina Geologic Survey 1991).
Photo 1.1: Near Aurora in Beaufort County is the
largest phosphate mine in the state. An important component in fertilizer, phosphate is
mined close to and sometimes extracted from
under the Pamlico Sound. Phosphate is the
state’s most important resource in terms of dollar value.
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Photo 1.2: Mining wastes are piled high above
adjacent residential area, along NC 274
north of Bessemer City in Gaston County.
filler, paint and insecticide carriers (North Carolina Geologic Survey 1991).
Further west lies the Charlotte Belt in the south and central sections with the Milton Belt to the north. Mostly igneous
rocks from 300-500 million years old, such as granite (CP 1.6),
diorite, and gabbro, comprise the Charlotte Belt (Photo 1.2).
Gneiss, schist and other metamorphosed intrusive rocks make
up the Milton Belt. Both of these belts provide good sources of
crushed stone for road aggregate and some cut for building purposes (North Carolina Geologic Survey 1991).
The Kings Mountain Belt, the smallest belt in the state,
consists of moderately deformed and metamorphosed volcanic
and sedimentary rocks which are about 400-500 million years
old. Lithium deposits here provide raw materials for chemical
compounds, ceramics, glass, greases, batteries, and television
glass (Photo 1.3) (North Carolina Geologic Survey 1991).
In the western most section of the Piedmont region, the
Inner Piedmont Belt is the most intensely deformed and metamorphosed segment. Metamorphic rocks range from 500-750
million years in age. Younger granitic rocks have intruded areas
of gneiss and schist (Photo 1.4). CP 1.7 shows the Stone Mountain State Park monadnock that is popular for recreational activities like hiking and climbing in Wilkes County. Forming the
boundary between the Blue Ridge and the Inner Piedmont Belt
is the northeast trending Brevard fault zone. Although this zone
of strongly deformed rocks is one of the major structural features in the southern Appalachians, its origin is poorly understood. Crushed stone for road aggregate and building construction is the principal commodity extracted and produced. Photo
1.5 shows the largest open-face granite quarry in the world, lo-
Photo 1.3: Crowders Mountain, located just a
few miles southwest of Gastonia in Gaston
County and part of the Kings Mountain
Belt, is composed of metamorposed volcanic-sedimentary rocks and is world-famous
for its lithium deposits.
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Photo 1.4: Some 25 miles north of Winstonsalem in Surry County, this rural setting
depicts the rolling terrain of the Inner
Piedmont Belt and of the Piedmont region. The familiar silhouette of Pilot
Mountain, one of the Piedmont granitic
monadnocks, is in the background.
cated at Mount Airy (North Carolina Geologic Survey 1991).
To the west is the mountainous region of the Blue Ridge
Belt. It is composed of rocks from over one billion to about onehalf billion years old and has a complex mixture of igneous,
sedimentary, and metamorphic rock that have been repeatedly
squeezed, fractured, faulted and twisted into folds (CP 1.8). Deposits of feldspar, mica, and quartz are basic materials used in
the ceramic, paint, and electronic industries. Olivine is mined
for use as refractory material and foundry molding sand. Precious stones of garnet, moonstone, ruby, saphire, aquamarine,
amethyst, hiddenite, rutile, quartz, and emerald are found in this
belt. The largest single emerald crystal found in North America
was mined at the Rist Mine at Hiddenite in 1969 and weighed
1,438 carats. A 13.14 carat emerald cut gem, the Carolina Emerald, was also found at this mine (North Carolina Geologic Survey 1991).
North Carolina leads the nation with important mineral
deposits including feldspar, lithium, scrap mica, olivine, and pyrophyllite. Additionally, the State ranks second in phosphate rock
production and ranks in the top five in clay and crushed granite
production. Figures 1.7a, b, and c show the spatial characteristics of mineral producing areas, mine earnings, and mining employment, respectively. It is important to note the role that geologic processes have and will continue to play in the relevant
aspects of rocks and minerals, land surface, soils and groundwater potential (North Carolina Geologic Survey 1991).
Figure 1.8 illustrates the state’s geologic time scale including the major geologic events. When comparing this table
with the Generalized Geologic Map (CP 1.9) we see the spatial
component of the geologic time scale as it exists today.
Land Surface and Topography
Elevation or topography varies across the state with the
most marked difference in an east-west direction (CP 1.10). While
this graphic does well to give us an idea of what the generalities
of elevation are, a shaded relief map (CP 1.11) shows a more
detailed and intricate design of the land surface within the state.
A shaded relief depiction of the state allows us to better visual-
Figure 1.7: Mining Activity.
Source: Modified from North Carolina Geologic Survey, 1991.
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Figure 1.8: Geologic Time Scale.
Source: Modified from North Carolina Geologic Survey, 1991.
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Photo 1.5: At the Mt. Airy Granite Mining
Company, Precambrian granite is being
“peeled off” in one of the largest open-face
granite quarry operation.
ize the state’s subtle relief changes. Relief is the local or regional
change in elevation between high and low points of land surface.
The eastern-most portion of the state begins at sea level
with the outer banks (CP 1.12), a series of barrier islands separating the Atlantic Ocean and the sounds (Photo 1.6). These features are a result of sediments being moved by offshore currents
as the coast slowly emerges (Box 1B). Poorly drained areas,
sand flats, bays, and sounds characterize the Tidewater region
(Photo 1.7). Westward across the Coastal Plain there is another
noticeable change in elevation when one reaches the Fall Zone.
Here elevation gradually increases to over 91 meters (300 ft)
above sea level. As we approach this zone the land surface becomes gently rolling with the prominent Sand Hills on the southwest margin.
Further westward the Piedmont area consists of irregular
rolling plains with a local relief of 30 to 91 meters (100 to 300
ft). Elevations reach 457 meters (1,500 ft) some 322 kilometers
(200 mi) west of the Fall Zone. About 45 percent of the state is
occupied by the Piedmont. From between one-half to three-quarters of its surface profile is in gentle slopes (up to 8%) on the
upland surface. The term plateau is sometimes used in describing the Piedmont area. Remnants of more resistant rock, known
as monadnocks, form high hills and crests. Often called mountains by the early settlers of the region, these include the Brushy
Mountains in Alexander, Caldwell, and Wilkes Counties; Kings
Mountain in Cleveland and Gaston Counties, Sauratown Mountains in Stokes County; South Mountains in Burke, Cleveland,
and Rutherford counties; and the Uwharrie Mountains in
Davidson, Montgomery, and Randolph counties (CP 1.13). Located close to the large population centers of the Piedmont Crescent the mountains provide recreational activities, camping, hiking, and fishing in the state and national forests, and game lands
are popular leisure activities. The local terrain also proves to be
easily formed into artificial lakes and reservoirs. These are used
as water supplies for nearby cities, for flood control, and as open
space for recreation.
Photo 1.6: Hatteras Island, where Sea Island Wildlife Refuge meets a small village with a considerable number of vacation homes. Note the
low vegetation that helps stabilize these island dunes.
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Box 1B: Barrier Island Formation.
Coastal barriers stretch in an irregular chain from Maine
to Texas. These elongated, narrow landforms are composed
of sand and other loose sediments transported by waves, currents, and wind. The term “barrier” identifies the structure as
one that protects other features. North Carolina’s barrier islands protect its mainland from the destructive effects of powerful storms (refer to Chapter 2) and their resulting waves.
Barrier islands are dynamic landforms, and as such they are
constantly changing. Popularity of these islands as vacation
destinations has placed ever-increasing development pressures
on these shifting landforms. This protection is vital to the
productivity of estuary and lagoon habitats. Natural or human disturbances to these barrier islands will have an impact
on this productivity (refer to Chapter 8 for Hurricane Floyd’s
impact) (Leatherman 1988).
Barrier islands can originate and develop in a number
of different ways. However there are three main theories of
barrier island genesis (Hoyt, Leatherman, and Dolan and
Lins):
a: Barrier island formation by spit accretion and inlet breaching.
A) spit growth and later segmentation by inlets (a);
B) mainland beach ridge submergence (b); and
C) up-building of submarine bars
North Carolina’s Outer Banks is best explained by
Hoyt’s model (b). These probably were once the dunes of
ancient beaches formed when sea level was much lower. During the past 15,000 years rising seas breached the dune line,
creating the shallow sounds behind them and leaving the dune
islands high and dry (Figure 1.8) (Early 1993). Conversely,
the Carolina capes may have evolved from Pleistocene-age
river deltas formed when sea level was (91 m/300 ft) lower
than present (a). As sea level rose these large deltaic sand
bodies were reworked by waves and currents and pushed landward. In the process, sand spits could have grown off these
eroding deltaic headlands, forming the barriers that eventually bridge the capes (Leatherman 1988).
Whatever the origin of these islands may be there is no
question that they are attracting more and more people every
year. With the instability of these islands for urban infrastructure and dangers from severe storms, loss of life is not uncommon. Understanding the natural dynamics of barrier islands is the key to recognizing and estimating the short and
long term hazards of living on them (Dolan and Lins 1986).
b: Hoyt’s theory of barrier island formation by drowning of a
mainland dune ridge.
Source:Leatherman, Barrier Island Handbook, 1988.
12
Photo 1.7: The Intracoastal Waterway passes
through Hyde County, providing a safe route
for waterborne goods and leisure travel.
The Mountain Region rises abruptly from the Piedmont
along an escarpment known as the Brevard Fault. Along the eastern part of this region is the Blue Ridge Mountains with elevations to about 1,219 meters (4,000 ft) and a few peaks to almost
1,829 meters (6,000 ft). Here we have a class of open, low mountains with a profile type of over three-quarters in gentle slopes.
Within the state, 43 peaks exceed 1,829 meters (6,000 ft)
in elevation and 82 peaks are between 1,524 to 1,829 meters
(5,000 to 6,000 ft). Varying from 24 to 80 kilometers (15 to 50
mi) wide, the Great Smoky and the Unaka Mountains form the
western part of this region. They are low mountains with some
elevations exceeding 1,829 meters (6,000 ft). Mount Mitchell,
the highest peak in the eastern North America, reaches 2,037
meters (6,684 ft) and is part of the Black Mountains, a cross
ridge between the Blue Ridge and Smoky Mountains (North
Carolina Geologic Survey 1991).
Land Cover and Use
parent. Barrier Islands are popular for beach vacations and the
resort areas of Kitty Hawk, Nags Head, Hatteras, Ocracoke, Atlantic Beach, Long Beach, Holden Beach, and Sunset Beach appear on the map. On the opposite end of the state, we see the
urban centers of Asheville, Hickory, and the many smaller mountain communities like Jefferson, Boone, Spruce Pine, Brevard,
Cullowee, and Murphy, nestled on the valley floors. Note also
the easily identifiable escarpment of the Brevard Fault which
can be seen as land cover changes from grassland and pastures
mixed with forests in the Piedmont to the heavily forested Mountain region. In the southern part of the Coastal Plain Region appears, in stark contrast, an area spotted with elliptical lakes and
wetlands, with some of them cultivated. Known as the Carolina
Bays, these wetlands are of disputed origin (Box 1C). The patterns of land cover and use that are present in CP 1.14 are fascinating and merit reference throughout the use of this book. Percent Land Cover (Figure 1.9) illustrates the distribution among
the major land cover types found in the state. Forest cover domi-
Differences in geologic structure create differences in land
surface and topography, which in turn influence differences in
the land use and cover. Land cover includes natural and cultivated vegetation, lending itself to classification and to the mapping of resulting features. Land use, on the other hand, refers to
how people utilize the land. Mapping of land cover is often accomplished through the use of remotely sensed imagery acquired
from satellites (CP 1.14). A detailed description of acquisition,
classification and mapping is included in Box 1C. Differing uses
of the land in each of the state’s primary regions reflect some of
the impacts of geologic processes. Several patterns readily
emerge. Notice the vast amount of cultivated land in the Coastal
and Tidewater regions in contrast to the urbanization of the Piedmont. A crescent of urban centers emerges in the south central
part of the state from Charlotte, northward to Winston-Salem,
High Point, and Greensboro, then eastward through Burlington,
Durham, and Raleigh. Also, there is observable urban activity in
the Coastal Plain Region in the Fayetteville and Jacksonville
areas. In the Tidewater, Wilmington as well as the long narrow
corridors of coastal developments along the outer banks are ap-
Figure 1.9: Percent Land Cover.
Source: Modified from North Carolina Center of Geographic
Information and Analysis, 1998.
13
nates the state, broadleaf deciduous forest covering over 40
percent and needle bearing evergreen forest covering over 19
percent of land area.
WATER RESOURCES
Introduction
Water is an essential component of the physical environment. While the value of our water resources is great, the pressure of human use is considerable and in some places excessive
and detrimental to the local quality of life. A growing population has placed increasing demands on water for use in recreation, power generation, industry, agriculture, and domestic activities (Table 1.2). While these are coupled with many opportunities, if this resource is not cared for the problems of pollution,
flooding, misuse, and overuse are the result. An understanding
of water as a resource, and the ways it impacts our lives is, therefore, critical to an appreciation of land and life in North Carolina.
Hydrologic Cycle
The system of movement, exchange, and storage of the
earth’s water in the forms of a gas, liquid or solid is known as
the hydrologic cycle (Figure 1.10). While this demonstrates how
natural systems move water through our environment, North
Carolinians are well aware that people have modified these systems in different ways and in doing so have changed the environment in which we live. People dam, drain, pump, divert, and
consume water. All these actions impact our landscape and place
demands on the precious resource, water.
Distribution of Earth’s Water
Oceans hold 97.2 percent of the water on earth. This portion is, of course, salt or brackish water. Another 2.15 percent is
held in ice sheets and glaciers, and 0.62 percent is held in ground
water supplies. The remaining amount, 0.03 percent, is water in
stream channels, fresh water lakes, soil water, saline lakes and
inland seas, or in the atmosphere. A truly small amount of the
earth’s water resource, about two-thirds of one percent, is available to a water-hungry, industrializing and urbanizing expanding earth population.
Figure 1.10: Hydrologic Cycle.
Source: Modified from North Carolina Water, 1994.
Surface Water
An average annual precipitation of 122 centimeters (48 in)
over the state amounts to some 159 trillion liters (42 trillion gl) of
water with two-thirds of this returning to the atmosphere through
evapotranspiration. Evapotranspiration is the water loss to the
atmosphere by evaporation from the soil and other surfaces plus
transpiration from vegetation. The remaining one-third finds its
way as land surface or underground water, to eventually reach
the sea. About 88 percent of our surface land area of 136,197
square kilometers (52,586 sq mi) drains 42 trillion liters (11 trillion
gl) into the Atlantic Ocean, and 11 trillion liters (3 trillion gl) drain
from the remaining 12 percent into the Gulf of Mexico.
Major River Systems and Drainage Basins
Figure 1.11 illustrates the major surface drainage patterns
with the Eastern Divide, commonly referred to as the Eastern
Continental Divide. Seventeen major river systems comprise the
states drainage basins or watersheds. Table 1.3 lists these watershed areas and stream lengths.
The Blue Ridge Mountains form the Eastern Divide that
separates surface drainage flow east and west. Impeding surface
flow are almost 50,000 lakes and reservoirs. All of those in the
Mountains and Piedmont are artificial. The two largest are
Fontana Lake on the Little Tennessee River and Lake Norman
on the Catawba River (CP 1.15).
Type of Use
Liters (millions)
Domestic and Commercial
2,983
Thermoelectric
27,520
Industrial and Mining
1,991
Agriculture
662
33,156
Total Water Used per Day
Table 1.2 Water Use by Sector.
Source: Modified from North Carolina Water, 1994.
14
Gallons (millions) Percent
788
9
7,270
83
526
6
175
2
8,760
100
Watershed Name
Broad River
Cape Fear River
Catawba River
Chowan River
French Broad River
Hiawassee River
Little Tennessee River
Lumber River
Neuse River
New River
Pasquotank River
Roanoke River
Savannah River
Tar-Pamlico River
Watauga River
White Oak River
Yadkin-Pee Dee River
Square Kilometers Square Miles Stream Kilometers Stream Miles
3,919
1,513
2,334
1,450
24,144
9,322
9,984
6,204
8,508
3,285
4,896
3,042
3,569
1,378
1,259
782
7,327
2,829
6,619
4,113
1,665
643
1,587
986
4,652
1,796
4,339
2,696
8,638
3,335
3,674
2,283
16,149
6,235
4,828
3,000
1,950
753
1,336
830
9,415
3,635
747
464
9,068
3,501
3,885
2,414
443
171
336
209
14,429
5,571
3,885
2,414
531
205
455
283
3,274
1,264
446
277
18,702
7,221
9,423
5,855
Table 1.3 North Carolina Watershed Areas and Stream Lengths.
Source: North Carolina State University Cooperative Extension Service, 1997.
Box 1C: State Wide Land Cover – A Comprehensive Mapping Project.
The North Carolina Geographic Information Coordinating Council (GICC), established by Governor Hunt through
Executive Order Number 16, directs a statewide data coordination initiative. This initiative is detailed in the “Strategic
Plan for Geographic Information Coordination in North Carolina,” adopted in 1994 by the Council. The Center for Geographic Information and Analysis (CGIA) provides staff support to the Council and its five standing committees: State
Mapping Advisory Committee (SMAC), Geographic Information Systems (GIS) Technical Advisory Committee, State
Government GIS Users Committee, the Affiliated GIS Users
Group, and the Federal Interagency Committee. Additionally,
CGIA manages and distributes much of the State’s digital
geographic data. The individual data sets, created by many
government agencies, form a growing resource that is used
by all public agencies, lead regional organizations, universities, community colleges, utilities, and the private sector.
A full service agency, CGIA works with clients on the
generation, analysis, and distribution of geographic information. Services include system analysis and needs assessment,
system setup assistance, programming, training, data layer
creation and digitization, geographic data analysis, custom
hard copy maps and overlays, plotting services, report generation, and digital data distribution. All work is performed
on a cost recovery basis.
This land cover mapping project was developed and
expedited by CGIA and is a new addition to the North Carolina
Corporate Geographic Database. The data layer is a combined
effort on the part of both federal and state agencies, as well as
other entities.
The land cover data is a result of a combination of
twenty-two multi-temporal Landsat Thematic Mapper (TM)
satellite data scenes. One TM satellite scene covers an area
of approximately 185 by 185 km (115 mi ). This data is a
raster or grid data structure, with each raster representing a
30 by 30 m ground grid cell size. Consequently, objects of
this size or smaller will not be included in a data set with this
spatial dimension. While satellite imagery at this spatial resolution can give enough detail to be useful at the state or county
level, it may not be appropriate for use by small communities, towns, and cities. This seamless data covers the State.
EarthSat classified the data through digital image processing
techniques into 23 original land cover categories, based on
the 1994 CGIA publication “A Standard Classification System for the Mapping of Land Use and Land Cover.” The final
product as seen on CP 1.14 is a combined version of the original data as the detail of such a file is too great to show at this
scale.
For more information about CGIA and available digital data about North Carolina visit their home page on the
World Wide Web: http://www.cgia.state.nc.us.
15
Natural lakes are only found in the Coastal Plain and the
Tidewater regions occupying depressions in flat, peaty areas such
as Lake Mattamuskeet, the largest lake in the state with a surface area of almost 43,000 acres, and smaller elliptical ‘Carolina Bays.’ Carolina Bays are a unique land surface (CP 1.16a
and b), which still causes much discussion on just how they were
formed (Box 1D). The bays vary in size from less than 20 meters
to over 3 kilometers, with the more notable bays including Lake
Waccamaw and White Lake.
Stream flow or runoff varies greatly with location, and
daily and seasonal fluctuations. This affects water quality and
use as well as the propensity for flooding. Physical and cultural
environmental factors control stream flow. These include type,
amount and intensity of precipitation, summer air temperature,
evapotranspiration rates, size of drainage basin, topography, soils,
surficial geology, groundwater discharge, and land cover. Human activity also affects stream flow through different types of
land use, amount of impervious materials (rooftops, asphalt, and
concrete), as well as impoundment structures (sedimentation
ponds). Average runoff is greatest in the headwaters of the French
Broad River in Jackson and Transylvania Counties, amounting
to over 2.5 million gallons per square mile. Some of the highest
amounts of rainfall are located in this area of the state and environmental conditions provide high runoff amounts. In contrast,
the northern Piedmont has the lowest runoff with less than 0.6
million gallons per square mile.
Surface Geology and geologic processes are controlling
factors of the drainage pattern development created through the
erosion process. A dendritic or tree-like pattern characterizes
drainage in the Piedmont, with most rivers flowing toward the
southeast. Rivers in this region often appear muddy as tiny clay
particles from adjacent soils are suspended in the water.
In the Coastal Plain streams tend to parallel each other
and then either meander in broad flood plains or become braided
near the coast. This is because they are carrying a much greater
silt load than the water volume can handle (CP 1.17).
The western drainage has a more rectangular pattern often
dictated by differences in rock type or geology. Most of the
streams in the Mountain Region have little or no flood plains
because erosion is still carving the area, forming many V-shaped
valleys (CP 1.18), and often contain numerous waterfalls and
rapids as elevation changes occur rapidly (CP 1.19 and Photo
1.8). However, the New River Basin, the third largest of this
region, tells a different story. Years ago, an ancient mountain
range was eroded almost to sea level before today’s Appalachian
Mountains rose and lifted the basin. Rejuvenated and revitalized, the river’s erosion continued with more vigor. Presently,
the course being carved by this river meanders through the landscape, and the path traveled resembles that of one in the Coastal
Plain. It is rare that rivers in mountainous regions have these
characteristics, but that is why this river is often called the‘Old’
New River. Watauga County is the source of the New River,
(Photo 1.9 and 1.10).
North Carolina State University Cooperative Extension
Service described each of the seventeen basins in the map publication “North Carolina Watersheds” (Figure 1.11). The
decriptions give insight into more than the rivers as just a source
of water, by providing valuable information on the individual
character and importance of each basin, and are summarized
here with.
Located in the southwestern part of the state is the Broad
River basin. It flows through Hickory Nut Gorge, with its scenic
boulder gardens in the Rocky Broad, down to Lake Lure. Lake
Lure is a popular recreation and tourism destination and was
also the site for the movie “Dirty Dancing.”
The Cape Fear River Basin is entirely within the state’s
borders and comprises its largest watershed. Tributaries of this
basin include the Haw and Deep Rivers which drain much of the
Triangle and Triad urban areas and flow in a southeasterly direction, as do all of the basins that begin in the Piedmont or
Coastal Plain regions except for the Roanoke Basin. Its upper
reaches are drained by Town Fork Creek, and then by the northeast flowing Dan River. The latter joins the Roanoke River in
Virginia.
Photo 1.8: Pearson Falls in Polk County is one of
the many waterfalls that characterize the area
as surface water drains the Mountain-Piedmont
region border.
16
Photo 1.9: South Fork of the New River, a Wild
and Scenic River, was designated a national
Heritage River in 1998. The river flows north
through Ashe County prior to entering Virginia.
During the summer, Jordan Lake (in the upper Cape Fear
Basin) is home to more American Bald Eagles than anywhere in
the United States. The lower Cape Fear Basin is native habitat
for the rare and indigenous Venus Flytrap plant and the Redcockaded Woodpecker.
Headwaters of the Catawba River originate in the rugged
terrain of the of the Blue Ridge, where the Linville River has
carved a spectacular gorge more than 610 meters (2,000 ft). These
headwater streams are classified as Trout Waters, and this is one
of four rivers designated as a State Scenic River. The main channel of the Catawba River has seven hydropower reservoirs in
North Carolina beginning with Lake James and continuing to
Lake Wylie at the South Carolina border. These reservoirs provide electrical power, water supplies, and recreation for the most
densely populated watershed of the state. They also receive
treated wastewater, as well as overflows of sewage from private
and public septic systems.
The Chowan River basin is part of the Albemarle-Pamlico
estuarine system and is one of the smaller basins in the State. All
of the streams and rivers in this system are free flowing or tidal
freshwater. Most of the surface water in this basin originates as
groundwater from the adjacent swamps rather than runoff from
the surrounding land. This illustrates the important role that wetlands play in parts of our State’s freshwater supply.
Mountainous topography characterizes the French Broad
River basin, which contains Mount Mitchell. Whitewater rafting, canoeing, kayaking, and trout fishing enthusiasts find this
basin a favorite recreational destination.
The Lumber River is a unique blackwater river. It is flanked
by ancient forests of Bald Cypress trees, some of which are more
than 1,000 years old. Flowing south to join the Pee Dee River in
South Carolina, much of the river corridor has been designated
as a State Natural and Scenic River .
Photo 1.10: It is hoped that the recently bestowed ‘Heritage River’
designation will help provide protection against further development along the banks of the New
River.
17
Box 1D: An Unique and Interesting Landscape - The Carolina Bays.
Photograph Courtesy of Tom Ross.
An aerial view of Robeson, Columbus, and most of the
surrounding counties of the southern Coastal Plain reveal a
strange series of elliptical or oval pattern, whose long axis is
oriented northwest to southeast, that dot the landscape. Features like these are shallow depressions and are sometimes
filled with water and are known as “Carolina Bays”. Tom
Ross, a geographer at UNC-Pembroke, has investigated this
unique and interesting landscape. He notes that while the theories of origin abound from the extraterrestrial to more recent
and earthly theories that combine terrestrial factors, it is important to note the spatial extent and uses of the “Bays”.
Carolina Bays are found mainly in North Carolina and
South Carolina, although their area of occurrence extends from
southeastern New Jersey to northeastern Florida. Recent studies indicate that there are some 500,000 bays, but regardless
of the total number, these bays give the Coastal Plain a unique
character. Most bays consist of darker soils than the surrounding landscape and are partially surrounded by a low broad
sand rim. Bays are barely visible to the untrained eye at ground
level, but from the air even inexperienced observers can detect their presence.
Carolina Bays are ancient lakebeds, most of which have
dried up during the past several thousand years. However, in
periods of heavy precipitation, most bays collect runoff water,
which is held for several hours or days above the zone of
saturation. A few bays have a natural, constant source of water,
the two largest being Lake Waccamaw and Bay Tree Lake. A
dozen or so other bays are permanently ponded, but most are
swampy or wetland areas that contain water only during wet
periods. The term Carolina Bay is derived from the numerous
sweet, red and loblolly bay trees growing in and around the
Bays, not because they are maritime bodies. Carolina Bay
vegetation is not restricted to bay trees, however. It is common
to find vegetated lakes, grass-sedge prairies and cypress-gum
swamps in Bays. Other Bays support pond and loblolly pine,
and in drier portions, scrub oaks (Figure 11.6).
Human activity is impacting Carolina Bays. Pressures
of development, recreation, and agriculture are changing the
ecology of the Bays. Bulldozing, ditching, draining, and
pumping may hide or even destroy all evidence that the Bays
ever existed.
18
Figure 1.11: Surface Waters and River Basins.
Source: Modified from North Carolina Center of Geographic Information and Analysis, 1998.
Emptying into the Pamlico Sound, the mouth of the Neuse
River flows approximately 322 kilometers (200 miles) from its
headwaters in the Triangle urban area. As this river flows towards the southeast, it crosses the Fall Zone (see Chapter 3),
with this elevation change increasing the velocity and providing
the power for the river to carve out cliffs and canyons more than
30 meters (100 feet) deep.
The New River originates on the western slopes of the
Blue Ridge and flows northward through Virginia and West Virginia, draining into the Kanawha, Ohio and Mississippi rivers
before reaching the Gulf of Mexico. This river is designated as a
national Wild and Scenic River as well as being bestowed the
recent distinction of a Heritage River by former President Clinton
(Photos 1.9 and 1.10). It is also a favorite river for canoeing,
tubing, and trout fishing.
Most of the water resources in the Pasquotank River basin
are contained in estuaries and wetlands, along with 3,513 square
kilometers (1,356 square miles) of saltwater. The waters of the
Pasquotank are also black waters, stained by the naturally occurring acidic tannins that leach from the organic soils of the
surrounding land.
Photo 1.11: The Boone Reservoir in
Watauga County is an artificial
Blue Ridge lake that is fed by a
small mountain watershed at the
headwaters of the New River. Topography, or local relief, handicaps development of large-scale
reservoirs as those along the river
courses of the Piedmont Region.
19
The Roanoke River basin extends from the north-central
portion of the state to the Albemarle Sound. Trout populations
are supported in the western section of the watershed while the
eastern section includes one of the largest intact and least disturbed bottomland hardwood forests in the mid-Atlantic region,
with forest canopies that tower more than 30 meters (100 feet)
above the river. The primary sources of water in the watershed
are from twelve artificial lakes on the Roanoke and its tributaries in this state and in Virginia.
Headwaters of the Savanna River watershed originate in
southwestern North Carolina and then flow through South Carolina and Georgia and into the Atlantic Ocean. Portions are designated as a state Natural and Scenic River and other portions
are included in the Nationwide Rivers Inventory. More than 203
centimeters (80 inches) of rainfall per year fall in this basin,
highest in eastern North America, and it is known for some of
the most spectaular waterfalls of the east coast.
The Tar-Pamlico watershed includes the largest natural lake
of the state. Lake Mattamuskeet, winter home for dozens of songbird and waterfowl species, also supports an unusual freshwater
population of Blue Crab and the state’s largest breeding population of Ospreys. Included in the watershed are the Swanquarter
and Pocosin Lakes National Wildlife Refuges.
Draining westward into Tennessee is the mountainous terrain of the Watauga River watershed. This small watershed has
an excellent reputation for its trout fishing and beautiful scenery. The Watauga River Gorge is one of the deepest in the State
and has exceptional whitewater paddling. Over 15% of the waters in this basin are classified as High Quality Waters or Outstanding Resource Waters.
Most of the surface water of the White Oak River basin is
saltwater with only 446 kilometers (277 miles) of freshwater
streams. This river is habitat for many endangered or threatened
coastal species, including the Leatherback and Hawksbill Turtles
and the Croatan Crayfish. Its waters are also home for alligators
and many delicious seafood favorites including shrimp, clams,
oysters, and crabs. Unique for a coastal river, the banks of the
White Oak are lined with steep cliffs, which are remnants of
acient ocean dunes.
Rising on the slopes of the Blue Ridge escarpment, the
Yadkin-Pee Dee River system flows across the Mountain, Piedmont, and part of the Coastal Plain regions before entering South
Carolina. This watershed includes the Uwharrie mountains,
which are among the oldest mountains in the United States and
the site of the country’s first gold rush in 1799.
Clean Water Act introduced the topic of seasonal and temporary
wetlands. These areas are vulnerable to potential development
(Audubon 1996). Whatever the definition of wetlands is, we
know that they provide a valuable resource for wildlife habitat,
whether they are permanent or temporary. Figure 1.12 illustrates
a cross section of a typical wetland. Wetlands purify our drinking water, protect us from floods, and help support fish, waterfowl, and other wildlife. Refer to CP 1.14 to visualize the spatial
extent of the wetlands within North Carolina.
Surface Water Use
Surface water use in North Carolina varies with location
and purpose. The largest use of water in North Carolina is for
generating hydroelectricity. The Catawba River is heavily developed for this function. To generate electricity water flows
through a turbine, which turns a generator that produces electricity, and then water returns to the river. Although hydro generation is a clean system for the generation of energy, it does
require that the river be ‘controlled’ to avoid major fluctuations
in water quantity and assure a constant production level of hydroelectricity. Many industrial applications also require water
that is used as a coolant and then returned to the river (see Chapter 12).
Production of electricity in nuclear power generation facilities is a good example of such a use. This does not affect the
structure of the water, but it does impact its temperature. Agriculture is another major use of water in the State. Water used to
irrigate crops may become part of the plant. While some of this
is transpired back to the atmosphere, some of the water used in
irrigation is absorbed by the soil, some will flow back as surface
runoff, and some may become part of the groundwater supply.
Domestic and commercial uses also place demands on the quantity and quality of the water available. Our everyday activities
of doing laundry, washing the car, filling swimming pools, watering the lawn, and the like all place high demands on the water
supply. Table 1.2 details total water use and use by sector per
day.
Wetlands
An important surface water resource in North Carolina is
wetlands. Defining a wetland has become an important topic in
the United States during the past several years. Citizens concerned with their own property rights have taken an active role
in helping to define what is and what is not a wetland. The United
States’ first truly broad set of water-quality laws, known as the
Clean Water Act, was passed in 1972. The 1995 revision to the
Figure 1.12: Wetland
20
Our Primary problem is whether there is enough water in a
local system to provide for uses. Areas that are experiencing
rapid growth and development may be prime shortage areas.
Another concern is the quality of water as it is used for various
functions. It may become so contaminated with various pollutants that it becomes unusable for human consumption, cooking
and drinking, as well as in irrigation. Today, even some of the
industrial uses require drinking quality water (North Carolina
Water, 1994).
Surface Water Pollution (point versus non-point sources)
People have modified the surface drainage patterns,
through changes in the water flow, and have contaminated our
surface waters with large amounts of wastes. Surface water pollution occurs in many ways and can be classified into two broad
categories or sources, point and non-point.
Point pollution sources are where direct contamination
occurs through the dumping of piped wastes or other systems of
discharge. Such was the case in western North Carolina with
this kind of pollution of the Pigeon River from the Champion
International plant contamination (CP 1.20).
Non-point sources cover large areas that create a cumulative impact on the quality of water. This often occurs through
varied agricultural practices, development, or recreational areas
such as golf courses. This is often a result of fertilizers, high
animal wastes, or large amounts of sediment finding their way
to surface water flow. This type of pollution occurs throughout
the state at varying scales but perhaps is concentrated in the
Coastal Plains and Piedmont regions where agriculture is a dominant activity. As by its definition it is difficult to assess exactly
where this pollution begins.
Ground Water
Ground water refers to all subsurface water. Figure 1.10,
Hydrologic Cycle, illustrates how water moves through the environment. Note that there are several factors that affect ground
water vulnerability. These are yearly rainfall, depth to water,
aquifer type, soil type, and elevation. Ground water infiltrates
subsurface materials through cracks and pores, and supplies about
70 percent of domestic water used. Natural springs act as a discharge source, however, most of the groundwater is accessed
through drilled wells to support human activity such as domestic uses or farming. Rates of flow and total storage amounts vary
greatly according to the subsurface materials. The level of the
groundwater will also vary with the intensity of recharge (rainfall) and discharge (water usage) into the water-bearing layer of
rock, or aquifer.
Acquifers and the Ground Water Table
An aquifer is a rock mass or layer of both high porosity
and high permeability that readily transmits and holds ground
water. Ground water is subsurface water occupying the saturated zone and moving under the force of gravity. Figure 1.13
illustrates a cross sectional view of subsurface materials that
produce various aquifer situations. This geologic structure is crucial to the subsurface areas that will or will not have productive
aquifer regions.
Productive aquifers are abundant in the Coastal Plains.
The geologic situation consisting of deep layers of porous unconsolidated sediments, or sedimentary rock, presents a setting
for high yields of groundwater. A combination of limestone and
sand forms the best aquifer with wells yielding over 1,000 gallons per minute. Comparison of the Geologic Structure (Figure
1.5) with the Productive Aquifers (Figure 1.14) map, and the
Ground Water Yields (Figure 1.15) map, illustrates a positive
correlation between these data sets. Those areas possessing underlying sedimentary rock are the most productive aquifers, while
areas consisting of metamorphic or igneous rock types have much
lower aquifer productivity.
Groundwater in the Mountains and Piedmont is generally
of low yield due to the predominance of hard crystalline rock. A
limited amount of water may be held in the upper layer of weathered bedrock, or porous saprolite. Water moves through the joints
and fractures serving as pipelines to drilled or dug wells. Occa-
Figure 1.13: Aquifers.
Source: Modified from North Carolina Geologic Surevy, 1991 and the North Carolina Atlas, 1985.
21
sionally an artesian spring will discharge along the base of a
slope where the water table reaches the surface. The best yields
in these regions coincide with areas having thick layers of saprolite and a large, low basin area for recharge.
Ground Water Use in North Carolina
Management of our water is a critical issue, not just the
amount but the quality. Human activity can adversely effect
groundwater supplies. The clearing of forest areas and the draining of wetland for farming have reduced the recharge of groundwater. Discharge has been increased through the drilling of more
wells to service development of resort areas, especially along
the coast. In some cases this has resulted in saltwater intrusion
and contamination of groundwater supplies. Dredging of channels for navigation and the straightening of streams to improve
surface drainage have likewise disturbed the natural balance of
the groundwater system.
Figure 1.14: Productive Aquifers.
Source: United States Department of Agriculture, A Forest Atlas of
the South, 1969.
Threats to Ground Water
Saltwater Intrusion
Saltwater intrusion is a problem found in most coastal areas, and North Carolina is no exception. Extensive development
of the areas adjacent to saltwater has created a need for additional fresh water. As fresh water is pumped out of the ground,
surrounding fresh water flows into the aquifer to replace the water
that has been pumped out. If fresh water is pumped out faster
than it can be replaced, then water from other sources will flow
into the aquifer. In the Tidewater region this water may come
from sounds, marshes, ponds, channels, and estuaries.
Pollution
Ground water contamination is just as possible as surface
water contamination. As the use of ground water continues to
increase, so does the possibility of contamination. The major
focus simply stated is the contamination of the aquifer. It occurs
much like saltwater intrusion, except that the seepage are contaminants from other sources. Commercial, industrial, institutional, and residential land uses are all potential pollution sources.
When space is made in the aquifer through increased pumping
and use of ground water, then the source of the recharge becomes the dominant factor. The water may be seeping from an
already contaminated surface or another ground water source.
Increasing concern in the State has been placed on underground
industrial gasoline and domestic fuel oil tanks buried during the
1940’s, 50’s, and 60’s that are failing and creating potential
groundwater pollution.
The Clean Water Act of 1972 and its 1995 revision coupled
with the more recent Safe Water Drinking Act may still fall short
to protect and reflect our current situation. This is tough, partly
because the conditions of water are difficult to capture in the
kind of unambiguous statistics lawmakers like, and partly because it has become increasingly apparent that the sources of
pollution are not just industrial and municipal institutions that
can be controlled by specific laws. The burden of pollution belongs to all of us.
Chapter 8 and the regional chapters (10-13) illustrate these
environmental concerns as they impact our need for both the
quality and quantity of our fresh water supply.
Figure 1.15: Ground Water Yield.
Source: Modified from the North Carolina Atlas,1975.
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