Water-resources data for the 2002 water year for North Carolina consist of records of ground-water levels and water quality of ground water; records of stage, discharge, and water quality of streams; and stage and contents of lakes and reservoirs. This report contains ground-water-level data from 143 observation wells and ground-water-quality data from 72 wells. The collection of water-resources data in North Carolina is a part of the National Water-Data System operated by the U.S. Geological Survey in cooperation with State, municipal, and other Federal agencies.
Records of ground-water levels were published from 1935 to 1974 in a series of Water-Supply Papers entitled "Ground-Water Levels in the United States." Water-supply papers can be found in the libraries of principal cities and universities throughout the United States or can be purchased from the U.S. Geological Survey, Earth Science Information Center, Open-File Reports Section, Denver Federal Center, Box 25286, Mail Stop 517, Denver, Colorado 80225.
Ground-water-level data beginning with the 1975 water year are published only in reports on a State-by-State basis. Beginning with the 1975 water year these Survey reports carry an identification number consisting of the two-letter State abbreviation, the last two digits of the water year, and the volume number. For example, this report is identified as "U.S. Geological Survey Water-Data Report NC-02-2. Water-data reports are for sale by the National Technical Information Service, U.S. Department of Commerce, Springfield, Virginia 22161.
Cooperative agreements between the U.S. Geological Survey and organizations of the State of North Carolina for the systematic collection of water-resources data began in 1895 and continued through 1909. Following a lapse of 8 years, the State of North Carolina resumed cooperation in October 1918. Organizations that have cooperative agreements with the U.S. Geological Survey and assisted in collecting the water-resources data contained in this report are:
The following organizations have cooperative agreements with the U.S. Geological Survey and assisted in the data-collection program by furnishing funds or services:
Brunswick County
Lumber River Council of Governments
The following Federal agencies assisted in the data-collection program by furnishing funds or services:
U.S. Marine Corps, Camp Lejeune
U.S. Marine Corps, Cherry Point, MCAS
U.S. Environmental Protection Agency
OBJECTIVE CONCEPT FOR GROUND-WATER-LEVEL DATA
The ground-water-level data collected during the 2002 water year from observation wells in the statewide program and special project wells are published in this report. The statewide program is a cooperative program between the U.S. Geological Survey (USGS) and the North Carolina Department of Environment and Natural Resources (DENR). Observation wells for this program are located so that the most significant data are obtained from the fewest number of wells in the major aquifers of the State. Monitoring wells for this program are categorized in one of two networks based on specific objectives (table 1). The first network, the natural-effects network, has the objective of measuring the effects of natural stresses on ground-water storage. This network contains climatic-effects wells, which monitor the effects of climate, such as rainfall and the duration of the growing season, on ground-water storage in unconfined aquifers. This network also contains terrane-effects wells which are used to define the effects of different depths to the water table, and topography and geology on ground-water storage in response to climatic stresses. The second network, the induced-effects network, defines the effect of human-induced stress on the ground-water system; the major induced stress being ground-water withdrawal by pumping. Within the induced-effects network are local-effects wells located near large-capacity pumping wells or well fields. These local-effects wells are used to measure daily or weekly water-level fluctuations. Areal-effects wells, also in the induced-effects network, are used to determine the status of ground-water storage in an aquifer over a large area and to aid in determining the areal extent of major aquifers.
The particular effect each well in the statewide program monitors is explained in the information header for each well. The headers for the special project wells contain a reference to those projects.
The major aquifers in North Carolina can be divided into two zones related to the physiographic provinces of the State. The Piedmont and Blue Ridge Provinces (fig. 1 GIF/PDF) extend across the western 60 percent of the State and are, for the most part, underlain by fractured, igneous and metamorphic rocks (fig. 2 GIF/PDF). The fractured igneous and metamorphic rocks have low permeability but are, nevertheless, the major aquifers in the Piedmont and Blue Ridge Provinces. These rocks are covered almost everywhere by regolith, which is either a clayey or sandy saprolite consisting of weathered parent material, or sand and clayey-sand alluvium. The regolith, although not a major aquifer, contains most of the ground water in storage and is a source of water to the underlying igneous and metamorphic rock aquifers. All observation wells in the Piedmont and Blue Ridge Provinces that were measured in the 1998 water year tapped the regolith.
The Coastal Plain Province covers the eastern 40 percent of North Carolina, where aquifers are within a wedge of sedimentary rock layers that dip and thicken to the southeast (fig. 2 GIF/PDF). The Coastal Plain sediments have been divided by Winner and Coble (1996) into 10 aquifers separated by confining units.
Ground water in the regolith of the Piedmont and Blue Ridge Provinces and in the surficial aquifer of the Coastal Plain Province generally is unconfined. Ground water in the other Coastal Plain aquifers generally is under confined conditions.
| Table 1.--Type, objective, and use of data from the North Carolina observation-well program [Adapted from Winner, 1981] |
||
| Type | Objective | Use of data |
|---|---|---|
| Natural effects | ||
| Climatic effects | To define effects of climate on ground-water storage. | Hydrographs showing natural changes in storage. |
| Terrane effects | To define effects of climate on ground-water storage as modified by topography and geology. | Hydrographs showing natural changes in storage as modified by topography and geology. |
| Induced effects | ||
| Local effects |
To define effects of ground-water withdrawals on storage near points of withdrawal. To define the hydraulic characteristics of aquifers To define effectiveness of confining beds in separating aquifers. |
Maps showing potentiometric-surface depressions. Hydrographs showing changes in water levels with time. Graphs showing water levels during pumping conditions as a function of pumping rates. |
| Areal effects |
To determine status of storage over the entire areal extent of the aquifer. To define regional continuity of aquifers. |
Regional water-level maps. Maps showing net change in storage over a specific time period. Define recharge and discharge areas for areal extensive aquifers. |
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