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A. R. Brockman

Publications and source records attributed to A. R. Brockman.

7 recordsLinked to original sources
USGS1993

Well-construction, water-level, and ground-water-quality data for Prince William County, Virginia, 1992

Well-construction, water-level, and ground-water- quality data were collected by the U.S. Geological Survey during 1989-92 in Prince William County, Virginia. The data are presented on a map, in tables, and in hydrographs to record ambient ground-water quality. Well construction data include descriptions of 182 well sites. Water-level data include measurements from 159 wells that were collected in the spring and fall of 1991 and hydrographs from six of the wells. Ground-water- quality data collected at 87 wells include analyses for major dissolved constituents, trace metals, nutrients, dissolved organic carbon, radon-222, and alkalinity. Environmental or stable isotope analyses were collected at 57 wells and dissolved gas analyses were collected at 18 wells. Field proper- ties were also recorded during sampling.

Open-File Report↗
USGS1990

Simulation of ground-water flow in aquifers in Cretaceous rocks in the central Coastal Plain, North Carolina

The principal sources of water-supply in Cretaceous rocks in the central Coastal Plain of North Carolina are the Peedee, Black Creek, and upper Cape Fear aquifers. Ground-water withdrawals from these aquifers have increased from about 0.25 million gallons per day in 1910 to over 29 million gallons per day in 1986, causing water-level declines as much as 160 feet. The maximum rate of water-level decline in 1986 is about 11 feet per year in the Black Creek aquifer. A quasi-three dimensional ground-water flow model was constructed and calibrated for the period 1900 to 1986 to simulate past water-level declines and to estimate the effects of future pumpage. Comparisons of 1,867 observed and model-computed heads were made at 323 well sites. The average difference between computed and observed water levels is -1 foot. About 68 percent of all the differences between computed and observed water levels falls in the range from -21.0 to 21.0 feet. Simulation indicates that the 29 million gallons per day of pumpage in 1986 was supplied by (1) increased recharge (net discharge of 2 million gallons per day in 1900 changed to net recharge of 18 million gallons per day in 1986), (2) increased lateral inflow to the aquifers of about 8 million gallons per day, and (3) depletion of ground-water storage of about 1 million gallons per day. Two pumping scenarios simulated head changes through 1991 and were based on (1) constant pumpage at the 1986 rates in each aquifer, and (2) continuing increases in pumping rates from 1986 through 1991 and rates varying from 10 to 19 percent per year for the three pumped aquifers. For scenario 1, water-level declines exceeded 5 feet locally; however, water-level rises of about 1 foot occurred in two areas. For scenario 2, water-level declines ranged from 1 foot to 30 feet in some pumping centers.

North Carolina↗
USGS1990

Ground-water pumpage and water-level declines in the Peedee and Black Creek aquifers in Onslow and Jones counties, North Carolina, 1900-86

Two aquifers in sediments of Cretaceous age, The Peedee and Black Creek aquifers, have become a major source of freshwater in Onslow and Jones Counties in North Carolina since about 1960. Prior to 1960, most water systems in this area withdrew water from younger sand or limestone beds that overlie the Peedee and Black Creek aquifers. Water-quality and economic considerations related to the treatment of water from these shallower aquifers led to increased use of the Peedee and Black Creek aquifers. Water withdrawals from the Black Creek and Peedee aquifers were about 10,000 gallons per day in 1933. By 1986, total withdrawals were about 7.8 million gallons per day, about 90 percent of which was supplied from the Black Creek aquifer. As a result of these withdrawals, ground-water levels have declined throughout Onslow and Jones Counties. The average rate of decline in static water levels in the Peedee aquifer is about 0.6 feet per year in central Jones County and about 1.4 feet per year in northern Onslow County. Rates of water level decline in the Black Creek aquifer average about 8.3 feet per year in Jones County to about 12 feet per year in northern Onslow County. Water levels in the Peedee aquifer have declined as much as 40 feet in Jones County and 80 feet in northern Onslow County since about 1900. During the same period, water levels in the Black Creek aquifer have declined as much as 120 and 160 feet in Jones and northern Onslow Counties, respectively.

North Carolina↗