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Richard H. Johnston

Publications and source records attributed to Richard H. Johnston.

18 recordsLinked to original sources
USGS1997

Hydrologic budgets of regional aquifer systems of the United States for predevelopment and development conditions

Ground-water budgets are presented in this report for 14 regionally extensive aquifer systems; pumpage from 11 of these systems provided from 40 to 50 percent of the ground water withdrawn in the United States during the 1970's and 1980's. The budgets are based on simulation results from computer-based models developed as part of the Regional Aquifer-System Analysis Program of the U.S. Geological Survey. Most of the models cover large areas (30,000-300,000 square miles) and generally are constructed with coarse-mesh finite-difference grids designed to simulate regional ground-water flow. The groundwater budgets derived from these models generally do not include local flow that enters and exits regional aquifers after traveling only a few miles or flow in overlying surficial aquifers. Budgets are presented for predevelopment and recent pumping conditions for most of the aquifer systems.

Professional Paper↗
USGS1994

Regional Aquifer-System Analysis Program of the U.S. Geological Survey, 1978-1992

The major ground-water systems of the United States have been investigated by the U.S. Geological Survey (USGS) through its Regional Aquifer-System Analysis (RASA) Program. During the first 15 years of the program (1978-92), 25 regional aquifer systems, including the most heavily pumped aquifers in the Nation, were intensively studied. As of mid-1992, 18 of the regional aquifer studies are completed or nearly so; 7 of the regional aquifer studies are ongoing, and compilation of a national ground-water atlas is in progress. This report summarizes the status of each RASA study and briefly describes the hydrology of the 25 regional aquifer systems. Important study results and examples of applications of study results are presented for some of the completed RASA investigations. The major contributions of the RASA Program are (1) assembly of data from numerous local studies and long-time data collections into systematic regional data bases; (2) comprehensive descriptions of the geologic, hydrologic, and geochemical characteristics of the regional aquifer systems; and (3) an understanding of how the regional ground-water-flow systems function under natural (predevelopment) and current (developed) conditions. To provide the comprehensive system descriptions, many of the RASA studies present, for the first time, maps depicting the hydrogeologic frameworks, water chemistry, potentiometric surfaces, and other aspects of entire regional aquifer systems. To provide an understanding of how the flow systems function, several of the completed RASA studies provide, for the first time, hydrologic budgets for both predevelopment and developed conditions. The results of the RASA Program are contained in nearly 900 reports published by the USGS, as well as various State and local agencies, and in articles published in scientific journals. A series of U.S. Geological Survey Professional Papers are being published to summarize and synthesize the results of each RASA study.

Circular↗
USGS1988

Summary of the hydrology of the Floridan aquifer system in Florida and in parts of Georgia, South Carolina, and Alabama

The Floridan aquifer system is one of the major sources of ground-water supplies in the United States. This highly productive aquifer system underlies all of Florida, southern Georgia, and small parts of adjoining Alabama and South Carolina, for a total area of about 100,000 square miles. About 3 billion gallons of water per day is withdrawn from the aquifer for all uses, and, in many areas, the Floridan is the sole source of freshwater. The aquifer system is a sequence of hydraulically connected carbonate rocks (principally limestone and some dolomite) that generally range in age from Late Paleocene to Early Miocene. The rocks vary in thickness from a featheredge where they crop out to more than 3,500 ft where the aquifer is deeply buried. The aquifer system generally consists of an upper aquifer and a lower aquifer, separated by a less permeable confining unit of highly variable properties. In parts of north Florida and southwest Georgia, there is little permeability contrast within the aquifer system. Thus in these areas the Floridan is effectively one continuous aquifer. The upper and lower aquifers are defined on the basis of permeability, and their boundaries locally do not coincide with those for either time-stratigraphic or rock-stratigraphic units. Low-permeability clastic rocks overlie much of the Floridan aquifer system. The lithology, thickness, and integrity of these low-permeability rocks have a controlling effect on the development of permeability and ground-water flow in the Floridan locally. The Floridan aquifer system derives its permeability from openings that vary from fossil hashes and networks of many solution-widened joints to large cavernous openings in karst areas. Diffuse flow pre-dominates where the small openings occur, whereas conduit flow may occur where there are large cavernous openings. For the Upper Floridan aquifer, transmissivities are highest (greater than 1,000,000 ft squared per day) in the unconfined karst areas of central and northern Florida. Lowest transmissivities (less than 50,000 ft squared per day) occur in the Florida panhandle and southernmost Florida, where the Upper Floridan aquifer is confined by thick clay sections. The hydraulic properties of the Lower Floridan aquifer are not well known; however, this unit also contains intervals of very high transmissivity that have been attributed to paleokarst development. The dominant feature of the Floridan flow system, both before and after ground-water development, is Upper Floridan aquifer springs, nearly all of which occur in unconfined and semiconfined parts of the aquifer in Florida. Before ground-water development, spring flow and point discharge to surface-water bodies was about 88 percent of the estimated 21,500 cubic ft per second total discharge. Current discharge (early 1980's) is about 24,100 cubic ft per second, 75 percent of which is spring flow and discharge to surface-water bodies, 17 percent is withdrawal from wells, and 8 percent is diffuse upward leakage. Pumpage has been and continues to be supplied primarily by the diversion of natural outflow from the aquifer system and by induced recharge rather than by loss of water from aquifer storage. The approximately 3 billion gallons per day pumped from the Floridan aquifer system has resulted in long-term regional water-level declines of more than 10 ft in three broad areas of the flow system: (1) coastal Georgia and adjacent South Carolina and northeast Florida, (2) west-central Florida, and (3) the Florida panhandle. Saltwater has encroached as a result of pumping in a few coastal areas. In general, the water chemistry in the Upper Floridan is related to flow and proximity to the freshwater-saltwater interface. In the unconfined or semiconfined areas where flow is vigorous, dissolved-solids concentrations are low (less than 250 milligrams per liter). Where the system is more tightly confined, flow is more sluggish and concentrations are higher (grea

Alabama, Florida, Georgia, South Carolina↗
USGS1988

Ground-water hydraulics, regional flow, and ground-water development of the Floridan aquifer system in Florida and in parts of Georgia, South Carolina, and Alabama

The Floridan aquifer system is one of the major sources of groundwater supplies in the United States. This productive aquifer system underlies all of Florida, southeast Georgia, and small parts of adjoining Alabama and South Carolina, for a total area of about 100,000 square miles. About 3 billion gallons of water per day were withdrawn from the aquifer system in 1980, and in many areas the Floridan is the sole source of freshwater. The Floridan aquifer system is a sequence of hydraulically connected carbonate rocks (principally limestone with some dolomite) ranging in age generally from late Paleocene to early Miocene. The rocks vary in thickness from a featheredge where they crop out to more than 3,500 feet where the aquifer is deeply buried. The aquifer system generally consists of an upper aquifer and a lower aquifer separated by a lesspermeable confining unit of highly variable properties. In parts of north Florida and southwest Georgia, where little permeability contrast exists among the units, the Floridan is effectively one continuous aquifer. The upper and lower aquifers, named the Upper Floridan aquifer and the Lower Floridan aquifer, are defined on the basis of permeability and their boundaries locally do not coincide with those for either time-stratigraphic or rock-stratigraphic units. Overlying much of the Floridan aquifer system are low-permeability clastic rocks. The lithology, thickness, and integrity of these rocks determine the degree of confinement and influence the distribution of natural recharge, discharge, and ground-water flow in the Floridan. The permeability of the Floridan aquifer system is derived from small openings including fossil hashes and solution-widened joints as well as large cavernous openings in karst areas. Diffuse flow predominates where the small openings occur, whereas conduit flow may occur where large cavernous openings are. Transmissivities are highest (greater than 1,000,000 feet squared per day) in the unconfined karst areas of central and northern Florida. Lowest transmissivities (less than 50,000 feet squared per day) occur in panhandle Florida and southernmost Florida where the Upper Floridan aquifer is confined by thick clay sections. The hydraulic properties of the Lower Floridan aquifer are not well known; however, intervals of high transmissivity occur that have been attributed to paleokarst development. Springs, nearly all of which occur in unconfined and semiconfined parts of the Upper Floridan aquifer in Florida are the dominant feature of the Floridan flow system. Before ground-water development, spring flow and point discharge to surface-water bodies were about 88 percent of the estimated 21,500 cubic feet per second total discharge, or about 19,000 cubic feet per second. Diffuse upward leakage, which occurs primarily in confined areas, accounted for the remaining 12 percent or about 2,500 cubic feet per second. Most of the recharge necessary to sustain springflow and aquifer discharge to streams and lakes occurs relatively close to springs and areas of point discharge to surface-water bodies. Recharge to the Upper Floridan is highest, averaging 10-20 inches per year, in unconfined or semiconfined spring areas. The proximity of high recharge to high discharge implies a vigorous and well-developed shallow flow system in the unconfined and semiconfined parts of the Upper Floridan aquifer. Ground-water flow is very sluggish in the parts of the aquifer system that are deeply buried and tightly confined, primarily southeast Georgia and northeast Florida, south Florida, and far-west panhandle Florida. Discharge to springs, streams, and lakes is practically nonexistent in the tightly confined areas and natural discharge occurs almost exclusively by diffuse upward leakage through thick overburden. The regional flow system has not been appreciably altered by groundwater development. However, increasing pumpage that reached 3 billion gallons per day by 1980 has resulted in long-term regional water level decline of more than 10 feet in three broad areas: coastal Georgia, adjacent South Carolina, and northeast Florida; west-central Florida; and panhandle Florida. Saltwater encroachment as a result of pumping has occurred locally in coastal areas. Pumpage from the Upper Floridan aquifer is supplied primarily by reduction of natural discharge and by increased recharge rather than by depletion of aquifer storage. About 20 percent is from reduced discharge to springs, streams, and lakes, about 20 percent is from reduced upward leakage, and about 60 percent is from increased recharge. Compared to predevelopment conditions, discharge to springs, streams, and lakes is reduced by less than 5 percent, upward leakage is reduced by about 30 percent, and recharge is increased by about 12 percent. Total recharge and, therefore, discharge increased from a predevelopment rate of 21,500 cubic feet per second to about 24,100 cubic feet per second by 1980. A considerable area remains of the Floridan aquifer system where large ground-water supplies may be developed. This area is largely inland from the coasts and characterized by high transmissivity and minimal development prior to the early 1980's. The major constraint on future development probably is degradation of water quality rather than water-quantity limitations.

Alabama, Florida, Georgia, South Carolina↗
USGS1987

Potentiometric surface of the upper Floridan aquifer in Florida and in parts of Georgia, South Carolina, and Alabama, May 1985

A map, constructed as a part of the Floridan Regional Aquifer-System Analysis (RASA), shows the potentiometric surface of the Upper Floridan aquifer for May 1985. It is based on measurements of water level or artesian pressure made in about 2 ,500 wells during the period May 13 to 24, 1985. Only measurements from tightly cased wells open exclusively to the Upper Floridan aquifer were used to make the map. These included 1,425 wells in Florida, 924 in Georgia, 133 in South Carolina, and 21 in Alabama. The potentiometric surface of the Upper Floridan aquifer changed little between 1980 and 1985. Significant water level declines were observed only in southwest Georgia and west-central Florida. Low rainfall during early 1985 and associated pumping for irrigation caused the declines in both areas. (Lantz-PTT)

Alabama, Florida, Georgia, South Carolina↗
USGS1982

Summary of hydrologic testing in Tertiary limestone aquifer, Tenneco offshore exploratory well--Atlantic OCS, lease-block 427 (Jacksonville NH 17-5)

A summary of hydrologic testing in an offshore oil-test well (LB427) drilled for Tenneco, Inc., 55 miles east of Fernandina Beach, Florida, is presented. The interval tested (1,050 to 1,070 feet below sea level) is in a calcarenite that is equivalent to the Ocala Limestone (late Eocene) of onshore Florida and South Georgia. At this site the Ocala forms the highly productive Tertiary limestone aquifer system of the southeastern United States. Pressure-head measurements indicate an equivalent freshwater head of 24 to 29 feet above sea level. These pressure-head measurements and an earlier one made in the nearby JOIDES J- I hole are the only hydraulic head determinations to date in the offshore extensions of any of the aquifers underlying the Atlantic coastal plain. A drill-stem test recovered water samples containing about 7,000 milligrams per liter chloride. However, seawater used in the drilling process apparently contaminated the samples and the formation water is considered slightly fresher. The head and salinity data from the Tenneco well suggest that the sampled interval lies in the transition zone between fresh and seawater in the limestone aquifer. These data, when viewed with similar data from JOIDES J-I, show the transition zone to slope very slightly landward. The interface position is probably intermediate between a position compatible with present-day heads and a position compatible with predevelopment heads.

Water Supply Paper↗
USGS1980

Summary of hydrologic testing in Tertiary limestone aquifer, Tenneco offshore exploratory well-Atlantic OCS, lease block 427 (Jacksonville NH-17-5)

A summary of hydrologic testing in an offshore oil-test well drilled for Tenneco, Inc. 55 miles east of Fernandina Beach, Florida, is presented. The interval tested (1,050 to 1,070 feet below sea level) is in a calcarenite that is equivalent to the Ocala Limestone (late Eocene) of onshore Florida and South Georgia. At this site the Ocala forms the highly productive Tertiary limestone aquifer system of the southeastern United States. Pressure-head measurements indicate an equivalent freshwater head of 24 to 29 feet above sea level. These pressure-head measurements and an earlier one made in the nearby JOIDES J-1 hole are the only hydraulic head determinations to date in the offshore extensions of any of the aquifers underlying the Atlantic coastal plain. A drill-stem test recovered water samples containing about 7,000 milligrams per liter chloride. However, seawater used in the drilling process apparently contaminated the samples and the formation water is considered slightly fresher. The head and salinity data from the Tenneco well suggest that the sampled interval lies in the transition zone between fresh and seawater in the limestone aquifer. These data, when viewed with similar data from JOIDES J-1, show the transition zone to slope very slightly landward. Heads at both wells are compatible with the onshore flow system as it existed prior to development.

Florida↗
USGS1978

Susceptibility of coastal plain aquifers to contamination, Fairfax County, Virginia; a computer composite map

A map is presented that classifies the Coastal Plain of Fairfax County, Virginia according to the susceptibility of the principal sand aquifers to contamination from surface sources. The following classification is used: (1) areas where leachate can readily enter the principal sand aquifers, (2) areas offering great natural protection against migration of leachate into the aquifers, and, (3) areas where the contamination risk is uncertain and onsite investigations are needed. Approximately 20 percent of the area is in the high-risk category. The map is computer generated and was made by combining four source maps depicting those hydrogeologic factors related to movement of contaminants into the aquifers. These factors are (1) lithologic character of the upper 25 feet of sediments, (2) clay thickness above uppermost sand aquifer, (3) hydraulic gradient direction and head difference between water table and artesian head in principal aquifer, and (4) areal occurrence of moderate to high transmissiviry aquifers. The map is designed to be used by planners with little or no earth-science background, however, a technical discussion for hydrologists and geologists is also provided. (Woodard-USGS)

Open-File Report↗
USGS1978

Planning report for the southeastern limestone regional aquifer system analysis

The southeastern limestone aquifer system is one of the major sources of ground water in the United States. Over 3 billion gallons of water are pumped daily making the aquifer the principal source of municipal, industrial, and agricultural water supply in large parts of Florida and Georgia and to a lesser extent in South Carolina, and Alabama. Another important use is the disposal of industrial wastes and treated sewage into parts of the limestone system containing saline water. A variety of problems have developed in the aquifer in recent years, principally declining water levels, saltwater intrusion in coastal areas, water-quality degradation, and inadequate supplies of fresh ground water locally. In 1978 the U.S. Geological Survey began a study whose goal is to provide a complete description of the hydrogeologic framework, geochemistry, and regional flow system of the limestone aquifer. A 4-year effort is planned that will include: (1) synthesis of all existing data and presentation on a series of regional hydrogeological and geochemical maps; (2) obtaining new hydrogeological information to fill data voids -- particularly where ongoing State and Federal programs are not likely to generate such data; and (3) design and calibration of a regional digital model of the aquifer system and detailed models of problem areas. Computer simulation will be used extensively to assess the effects of large withdrawals of ground water and waste injection into the aquifer.

Alabama, Florida, Georgia, South Carolina↗
USGS1977

Combined use of digital aquifer models and field base-flow data to identify recharge-leakage areas of artesian aquifers

As a result of continuous pumping since the 1890's, a regional cone of depression encompassing 363 km 2 has developed within the artesian Miocene Cheswold aquifer at Dover, Del. The aquifer is not being recharged significantly by leakage near the center of the cone, nor is major recharge induced in the updip subcrop area. The source of pumped water is apparently an area of about 65 km 2 northwest of Dover, where vertical leakage is substantial. This area was delineated by use of a digital aquifer model and streamflow data. A model of the unconfined aquifer was used to compute the unconfined aquifer's natural discharge to streams, assuming no leakage to underlying artesian aquifers. The area of substantial leakage to the underlying Cheswold was delineated as being coincident with that area where model-computed values of stream discharge were substantially larger than actual values of stream discharge determined in the field.

Delaware↗
USGS1976

Preliminary appraisal of ground water in the Franconia area, Virginia

A brief study of ground-water conditions in the Franconia, Virginia area was made using available data and rapid reconnaissance techniques: (1) to select optimum sites for water wells (2) to identify regionally favorable sites for recharge pits or surface-retention ponds for the disposal of excess storm-water runoff. The principal sources of ground water in the Franconia area are narrow elongate sand lenses within the Coastal Plain. The subsurface distribution of these sand lenses is unknown due to the lack of deep test drilling. However, a previous study of surface exposures suggests that the lenses are elongate in an east-west direction. Measurements of base flow and specific conductance of water in the small streams in the area were used to delineate sites most likely to be underlain by the sand lenses. A water-table contour map and shallow sub-surface geologic map can be used for preliminary selection of sites for recharge pits and retention ponds.

Virginia↗