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On September 2, 1895, U.S. Geological Survey (USGS) hydrographer Cyrus
Babb, with assistance from North Carolina State Geologist Joseph Holmes,
established a streamflow-measurement gage on the French Broad River at
Asheville (fig. 1). This streamflow gage, which was the first in the
South and only the third east of the Mississippi River, has been relocated
twice but otherwise has been in continuous operation. The USGS has worked
cooperatively for 100 years in North Carolina with Federal, State, and
local agencies to provide credible data and unbiased scientific
information. In 1995, the USGS operated about 400 streamflow-
ground-water- and water-quality-measurement stations in North Carolina.
The wide range in physiographic and geologic conditions across North
Carolina (fig. 2) reflects the diversity of earth science issues in the
State. The rocks that underlie the State yield rich soils and metallic and
industrial mineral resources. They also provide the framework over and
through which the State's water resources flow. |
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Figure 1. Streamflow-gaging station in nearly continuous
operation since 1895 on the French Broad River at Asheville.
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Figure 2. Map of North Carolina and diagrammatic geologic
section of the State.
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The 17 major rivers in the State supply drinking water to users in North
Carolina and adjoining States. The rivers also are used for commerce,
recreation, and wastewater discharge. The USGS, in cooperation with more
than 20 Federal, State, and local agencies, collects continuous streamflow
records at about 183 sites across the State. Intermittent measurements of
streamflow are made at about 70 sites in support of the State's
water-quality management program. The USGS also collects water-quality
data at more than 60 stream and lake sites. These data are required for
daily and long-term management of the State's surface-water resources,
determining the extent and severity of droughts, characterizing and
predicting conditions during floods, and monitoring and interpreting the
effects of human activities on streamflow and water quality. |
More than one-half of North Carolina's population relies on ground water
for water supply. The USGS collects and publishes ground-water data
collected from about 115 wells across the State. These data are needed to
determine the effects of human stresses, climate, topography, and geology
on ground-water storage. |
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Reservoirs supply drinking water to about one-third of the State's
residents and also provide valuable recreational opportunities and habitat
for wildlife. The USGS provides scientific information to a number of
State and local agencies that are responsible for protecting the water
quality of these important resources.
Eroded sediment from watersheds often accumulates in water-supply
reservoirs and lessens their storage capacity. USGS studies indicate that
sedimentation has reduced the storage volume of Lake Michie, near Durham,
by more than 20 percent between 1926 and 1992. Long-term monitoring by the
USGS indicates that the amount of sediment transported from land to surface
waters differs geographically across the State. The highest amounts are in
the YadkinÐPee Dee, the Catawba, and the upper Cape Fear River Basins--all
located in the heavily populated Piedmont region. |
The USGS, in cooperation with the Triangle Area Water-Supply Monitoring
Steering Committee, continues to investigate water quality in Falls and
Jordan Lakes and in six smaller reservoirs nearby. Falls and Jordan Lakes
supply drinking water to about 500,000 people in the RaleighÐDurham area.
Intensive sampling for suspended sediment, nutrients, metals, organic
pollutants, and the pathogens Cryptosporidium and Giardia keeps managers
informed of conditions that could threaten public health and use of the
reservoirs.
The Catawba River and its reservoirs supply drinking water and
hydroelectric power to the Hickory and Charlotte metropolitan areas. The
USGS, in cooperation with several local government agencies, is
investigating water quality in three of these reservoirs--Rhodhiss Lake,
Lake Hickory, and Mountain Island Lake. The studies use detailed computer
models to simulate the movement of contaminants and provide alternatives
for management of water quality.
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North Carolina is an important producer of industrial minerals including
lithium, mica, feldspar, phosphate, pyro-phyllite, and clays for brick
manufacture. Supplies of sand, gravel and stone for aggregate are
available for infrastructure repair and construction. Although metallic
minerals are not mined at present, the State contains reserves of gold,
copper, lead, zinc, silver, titanium, zirconium, tin and tungsten.
Competition for land, water, and biological resources is affecting the
local availability of clay, limestone, sand and gravel, building stone,
slate, and other industrial minerals. |
The USGS, in cooperation with the North Carolina Geological Survey (NCGS),
is preparing an inventory of known metallic and industrial mineral
resources. By using geological, geophysical, and geochemical studies, the
USGS also is preparing an assessment of potential undiscovered mineral
resources in the State. This information can assist Federal and State
land-management agencies, regional planners, industry, and local
governments in ensuring sound management and use of the State's substantial
mineral resources. |
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The USGS, in cooperation with Duke University, is conducting a
sand-transport study off Wrightsville Beach--the site of a beach
replenishment program for the last 30 years. Information on the movement
of sand in the nearshore area is used by coastal engineers to develop and
carry out strategies to protect and nourish beaches. During storms and the
post-storm recoveries of a beach, large quantities of sand are moved
offshore and back onshore. A side-scan sonar survey and sediment cores
collected off Wrightsville Beach show that sediment is transported from the
beach to the inner shelf (fig. 3). Gravelly shell hash from the
beachface, where it was placed as an artificial replenishment, was detected
offshore. This provides direct evidence of net offshore sediment
transport. These findings suggest that the beaches and the offshore region
must be treated as a single system to understand the transport of sand in
the nearshore and to evaluate erosion-mitigation measures. |
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Figure 3. Sidescan sonar mosaic of the area offshore of
Wrightsville Beach. Dark tones on the image represent areas of finer
grained sediments; light tones represent areas of coarser grained sediments.
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The USGS conducts regional ground-water studies to define aquifers, map
water levels, develop regional aquifer simulation models, and develop local
ground-water flow models. Ground-water levels in many areas of the Coastal
Plain are declining because of heavy pumping. For example, USGS studies
indicate that the ground-water levels in the upper Cape Fear aquifer in
parts of Bladen County have declined 90 feet (fig. 4); elsewhere in the
Coastal Plain, water levels have declined nearly 150 feet since the early
1900's. These studies are used by the North Carolina Division of Water
Resources and by numerous local governments to manage ground-water supplies
in the Coastal Plain. |
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Figure 4. Ground-water-level decline in the upper Cape
Fear aquifer of the southern Coastal Plain between fall of 1992 and fall of
1994.
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Several U.S. Department of Defense sites in North Carolina have some level
of contamination caused by past production, storage, or use of fuels,
chemical agents and munitions. Since the mid-1980's, the USGS has been
collecting hydrologic data and conducting investigative studies at Fort
Bragg, Camp Lejeune, and the Cherry Point Marine Corps Air Station (fig.
5). Goals of the studies include characterizing regional and site
hydrogeology, defining the extent of soil and ground-water contamination,
determining contaminant transport pathways, and predicting the fate of
contaminants. Innovative techniques for site characterization, chemical
detection, and biological remediation have been developed and tested as
part of these studies. The USGS monitors the progress of implemented
remedial actions and applies knowledge gained from one site to
another. |
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Figure 5. U.S. Department of Defense facilities near
Raleigh.
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North Carolina's topography is illustrated by 962 topographic maps at a
scale of 1:24,000 (1 inch equals 2,000 feet). These maps depict basic
natural and cultural features of the landscape, such as lakes and streams,
highways and railroads, boundaries, and geographic names. Contour lines
are used to depict the elevation and shape of terrain. These maps are
among the most popular and versatile products of the USGS and are useful
for civil engineering, land-use planning, natural-resource monitoring, and
other technical applications. The USGS, in cooperation with the NCGS, has
photorevised 10 percent of the State's 1:24,000-scale topographic maps near
Salisbury and Reidsville. In addition, several layers of information on
the printed maps are being converted to digital (computer-readable) files.
Political boundaries, water features, and transportation features are
available as digital line-graph files for about 90 percent of the maps in
the North Carolina series. Elevation data are available for about 80
percent of the State in a digital elevation-model format. The USGS has a
work-sharing agreement with the North Carolina Center for Geographic Information
and Analysis (CGIA) to produce digital data at the 1:24,000 scale for
two-thirds of the State. |
A digital orthophoto quarter-quadrangle (DOQ) is derived from digital
aerial photographs that combine the image characteristics of a photograph
with the scale accuracies of a map, and can be a component in geographic
information systems. The pixel resolution of a DOQ is 1 to 3 meters. The
USGS, in collaboration with the NCGS, the North Carolina Department of
Transportation, and the CGIA, is producing DOQ's for the eastern and
central portions of the State using 1993 leaf-off black and white
photography. This statewide program is coordinated through the State
Mapping Advisory Committee, which is a component of the Geographic
Information Coordinating Council that was established by the Governor.
Twenty-eight percent of the DOQÕs for the State are complete (October
1996). Matching State and Federal funds have been identified to complete
the State DOQ coverage. The USGS and the CGIA, in cooperation with the
South Carolina Department of Natural Resources, are preparing color
infrared DOQ's along the North Carolina-South Carolina border. |
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The USGS, in cooperation with the NCGS, has Earth Science Information
Centers (ESIC's) in the NCGS offices in Raleigh and Asheville. As part of
the national ESIC network, these offices provide computer-based searches
for information regarding paper maps, digital and remotely sensed data, and
other Earth science information. Data to ESIC offices are updated
annually. |
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At the request of the National Park Service, the USGS is conducting
bedrock, surficial, and geochemical studies in a 250-square-mile area of
the Great Smoky Mountains National Park. Results of the studies will
become part of a new computerized data base for use in improving management
of the Nation's most visited National Park. |
The statemap component of the National Geologic Mapping Program (NGMP)
provides funds to the NCGS for geologic mapping near Asheville and Raleigh.
Through edmap, another component of the NGMP, funding is provided to train
new field geologists. Geologic maps are essential for addressing many
geologic-related problems, such as land use and infrastructure planning,
mineral resource identification, and environmental assessment and planning. |
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The determination of circulation patterns and rates of movement of
water-borne materials in estuaries typically requires specialized
hydrographic data collection and the development of complex computer
models. Information on flow and transport is needed to allocate wasteloads
from point and nonpoint sources for protection of water quality, to
interpret water-quality and biological data, and to predict rates of
movement and dilution of spilled or released substances. The USGS, in
cooperation with the North Carolina Department of Environment, Health and
Natural Resources, has developed flow and transport models for segments of
the Roanoke, the Pamlico (fig. 6), and the Neuse River estuaries. These
models can be applicable in the management of water quality and the
protection of aquatic habitat. |
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Figure 6. Simulated solute-concentration distribution
resulting from actual tidal and wind conditions and a hypothetical release
of 25 million gallons per day and an initial strength of 100 percent
concentration.
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To provide information on the water quality of the Nation's water
resources, the USGS has implemented the National Water-Quality Assessment
(NAWQA) Program through a series of study units that encompass major
drainage basins and population centers. The goals of the NAWQA Program
are to describe current water-quality conditions, define long-term trends
in water quality, and provide an understanding of the natural and human
factors that affect water quality. Results from the NAWQA Program studies
provide policymakers, resource managers, and the public with an improved
scientific basis from which to evaluate water-quality-management
programs.
Parts of three NAWQA Program study units are located in North Carolina
(fig. 7). The AlbemarleÐPamlico drainage study began in 1991 and focuses
on evaluating the effects of land use on surface- and ground-water quality.
More than 80 wells and 100 surface-water sites have been sampled for
organic and inorganic chemicals (fig. 8). Data collection for the Upper
Tennessee and the Santee studies began in 1995.
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Figure 7. National Water-Quality Assessment Program study
units in North Carolina.
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Figure 8. Sampling shallow ground-water for nutrients and
pesticides.
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fs-033-96.pdf 679K