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Research about Georgia
Source-linked reports with geographic coverage including Georgia.
Water-resources activities, Georgia District, 1991
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Water-supply potential of major streams and the upper Floridan Aquifer in the vicinity of Savannah, Georgia
Long-term pumping from the Upper Floridan aquifer in the Savannah, Georgia, area has lowered ground-water levels, resulting in increased salinity of ground water by seawater encroachment at Hilton Head Island, S.C., and by saltwater intrusion at Brunswick, Ga. Increased pumpage could cause further salinization of the ground-water resources. The Savannah and Ogeechee Rivers can be considered potential water-supply sources for the Savannah, Ga., area, on the basis of historic stream flow records and water-quality constituents and properties examined. Analyses of stream-discharge data indicate that the minimum average discharges for 7 consecutive days for a 10-year recurrence interval (7010), was 5,460 cubic feet per second (ft3/s) at Savannah River near Clyo, Ga., and 192 ft3/s at Ogeechee River near Eden, Ga. For example, 90 percent of the time, flows in excess of the 7010 discharges are about 900 and 200 ft3/s, respectively. However, Georgia Department of Natural Resources, Environmental Protection Division, imposes a non-depletable flow criterion; thus, the actual quantity of water available for withdrawal probably would be less than flows in excess of minimum flow criteria, such as the 7Q10. A ground-water flow model was developed and used in conjunction with other previously calibrated models in the coastal area to simulate the effects of additional pumping on water levels near sites of seawater encroachment at Hilton Head Island and saltwater intrusion at Brunswick. Based on model simulations and the constraint of preventing water-level declines at locations of encroachment and intrusion, the potential of the Upper Floridan aquifer to supply additional water in the Savannah area is limited under present (1985) hydrologic conditions. The water-supply potential ranges from less than 1 million gallons per day (Mgal/d) in Liberty, McIntosh, most of Bryan, and southern Chatham Counties, Ga., and in southern Beaufort County, S.C., to more than 5 Mgal/d in northern Jasper and northern Beaufort Counties, S.C. Because of the limited water- supply potential, hypothetical alternatives involving redistributions, redistributions and small increases, and decreases in pumpage were simulated to determine the effects on water levels. These simulations indicate that reductions and redistributions of pumping would not adversely affect water levels at locations of encroachment and intrusion. Increased pumping would cause water-level declines, which might increase salinization of the fresh-water aquifer. .
Water resources data, Georgia, water year 1991
Water resources data for the 1991 water year for Georgia consists of records of stage, discharge, and water quality of streams; stage and contents of lakes and reservoirs; ground-water levels; and precipitation quality. This report contains discharge records of 114 gaging stations; stage for 28 gaging stations; stage and contents for 18 lakes and reservoirs; water quality for 138 continuing-record stations; water quality for 1 miscellaneous site; peak stage and discharge only for 97 crest-stage partial-record stations and 8 miscellaneous sites; water levels of 25 observation wells. These data represent that part of the National Water Data System collected by the U.S. Geological Survey and cooperating State and Federal agencies in Georgia.
Seismicity map of the state of Georgia
This map is one of a series of seismicity maps produced by the U.S. Geological Survey that show earthquake data of individual states or groups of states at the scale of 1:1,000,000. This maps shows only those earthquakes with epicenters located within the boundaries of Georgia, even though earthquakes in nearby states or countries may have been felt or may have cause damage in Georgia. The data in table 1 were used to compile the seismicity map; these data are a corrected, expanded, and updated (through 1987) version of the data used by Algermissen (1969) for a study of seismic risk in the United States. The locations and intensities of some earthquakes were revised and intensities were assigned where none had been before. Many earthquakes were added to the original list from new data sources as well as from some old data sources that has not been previously used. The data in table 1 represent best estimates of the location of the epicenter, magnitude, and intensity of each earthquake on the basis of historical and current information. Some of the aftershocks from large earthquakes are listed, but not all, especially for earthquakes that occurred before seismic instruments were universally used. The latitude and longitude coordinates of each epicenter were rounded to the nearest tenth of a degree and sorted so that all identical locations were grouped and counted. These locations are represented on the map by a triangle. The number of earthquakes at each location is shown on the map by the Arabic number to the right of the triangle. A Roman numeral to the left of a triangle is the maximum Modified Mercoili intensity (Wood and Neumann, 1931) of all earthquakes at that geographic location, The absence of an intensity value indicates that no intensities have been assigned to earthquakes at that location. The year shown below each triangle is the latest year for which the maximum intensity was recorded.
Chloride concentrations in the Upper Floridan Aquifer in the coastal area of Georgia, May 1990
No abstract available.
Potentiometric surface of the upper Floridan Aquifer, in the Albany area, Georgia, October, 1990
No abstract available.
Potentiometric surface of the Claiborne Aquifer in southwestern Georgia, October 1990
No abstract available.
Potentiometric surface of the upper Floridan Aquifer, in the Valdosta area, Georgia, October, 1990
No abstract available.
Potentiometric surface of the Clayton Aquifer in Georgia, October 1990
No abstract available.
Maps and cross sections depicting the shallow seismic stratigraphy of the continental shelf and slope off Georgia from interpretation of high-resolution seismic-reflection data
A seismic-stratigraphic study that used existing USGS high-resolution seismic-reflection profiles was made in the area of the TACTS coreholes. This report presents interpreted cross sections and isopach and structure-contour maps that resulted from that study and some preliminary conclusions. Structure contour maps showing depth below sea level to the upper Eocene, Oligocene, lower Miocene, middle Miocene, lower Pliocene, upper Pliocene, and Quaternary strata are presented. Maps that show the thickness of Oligocene, lower and middle Miocene, middle Miocene, lower Pliocene, upper Pliocene, and Quaternary strata and the total sediment thickness above the phosphatic middle Miocene strata are also shown.
Ground-water conditions in Georgia, 1990
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Geohydrology and evaluation of water-resource potential of the Upper Floridan aquifer in the Albany area, southwestern Georgia
In the Albany area of southwestern Georgia, the Upper Floridan aquifer lies entirely within the Dougherty Plain district of the Coastal Plain physiographic province, and consists of the Ocala Limestone of late Eocene age. The aquifer is divided throughout most of the study area into an upper and a lower lithologic unit, which creates an upper and a lower water-bearing zone. The lower water-bearing zone consists of alternating layers of sandy limestone and medium-brown, recrystallized dolomitic limestone, and ranges in thickness from about 50 to 100 feet. It is highly fractured, and exhibits well-developed permeability by solution features that are responsible for transmitting most of the ground water in the aquifer. Transmissivity of the lower water-bearing zone ranges from about 90,000 to 178,000 feet squared per day. The upper water-bearing zone is a finely crystallized-to-oolitic, locally dolomitic limestone having an average thickness of about 60 feet. Transmissivities in the upper water-bearing zone are considerably less than those in the lower water-bearing zone. The Upper Floridan aquifer is overlain by about 20 to 120 feet of undifferentiated overburden consisting of fine-to-coarse quartz sand and noncalcareous clay. A clay zone about 10 to 30 feet thick may be continuous throughout the southwestern part of the Albany area, and where present, causes confinement of the Upper Floridan aquifer and creates perched ground water after periods of heavy rainfall. The Upper Floridan aquifer is confined below by the Lisbon Formation, a mostly dolomitic limestone that contains trace amounts of glauconite. The Lisbon Formation is at least 50 feet thick in the study area, and acts as an impermeable base to the Upper Floridan aquifer. The quality of ground-water in the Upper Floridan aquifer is suitable for most uses; wells generally yield water of the hard, calcium-bicarbonate type that generally meets the U.S. Environmental Protection Agency's Primary or Secondary Drinking Water Regulations. The water-resource potential of the Upper Floridan aquifer was evaluated by compiling results of test drilling and aquifer testing in the study area, and by conducting computer simulations of the ground-water-flow system under the seasonal-low conditions of November 1985, and under conditions of pumping within a 12square-mile area located southwest of Albany. Results of test drilling, aquifer testing, and water-quality analyses indicate that, in the area southwest of Albany, geohydrologic conditions in the Upper Floridan aquifer, undifferentiated overburden, and Lisbon Formation were favorable for the aquifer to provide a large quantity of water without having adverse effects on the ground-water system. The confinement of the Upper Floridan aquifer by the undifferentiated overburden and the rural setting of the area of potential development decreases the likelihood that chemical constituents will enter the aquifer during development of the ground-water resources. Computer simulations of ground-water flow in the Upper Floridan aquifer, incorporating conditions for regional flow across model boundaries, leakage from rivers and other surface-water features, and vertical leakage from the undifferentiated overburden, were conducted by using a finite-element model for groundwater flow in two dimensions. Comparison of computed and measured water levels in the Upper Floridan aquifer for November 1985 at 74 locations indicated that computed water levels generally were within 5 feet of the measured values, which is the accuracy to which measured water levels were known. Water-level altitudes ranged from about 260 feet to 130 feet above sea level in the study area during calibration. Aquifer discharge to the Flint River downstream from the Lake Worth dam was computed by the calibrated model to be about 1 billion gallons per day; about 300 million gallons per day greater than was measured for similar low-flow conditions. The excess computed discharge was attributed partially to stream withdrawals for industrial use, non-reported use, and channel evaporation, but mostly to increased gradients and increased flow from the aquifer to the river than existed during calibration. Results from the calibrated finite-element model indicate that ground-water flow is dominated by inflow from regional-flow components to the west, north, and east of the study area, and by outflow to the Flint River downstream from the Lake Worth dam. Simulation results indicated that directions of ground-water flow were not changed appreciably by pumping at the November 1985 rates. However, vertical leakage from the undifferentiated overburden caused local deviations in the regional flow pattern. A sensitivity analysis that was performed on 18 hydrologic factors affecting the flow system in the Upper Floridan aquifer showed that computed water levels changed the most (were the most sensitive) in response to changes in hydraulic conductivity of the aquifer, vertical leakage coefficient and water level in the undifferentiated overburden, and stage of the Flint River downstream from the Lake Worth dam. Computed water levels were least sensitive to changes in well pumpage, flow across the northern boundary and from Lake Worth, the boundary coefficient for the Flint River downstream from the Lake Worth dam, and flow from Cooleewahee Creek. Simulations of six pumping scenarios in the area of potential development southwest of Albany showed that the Upper Floridan aquifer is capable of providing at least 72 million gallons per day from five locations (14.4 million gallons per day each) within this area without causing adverse affects on the flow system. The 72million-gallon-per-day scenario yielded a maximum drawdown of about 9.4 feet, which placed the water level in the Upper Floridan aquifer about 50 feet above the top of the lower water-bearing zone. Hence, the likelihood of aquifer dewatering, well interference, or sinkhole development from pumping as much as 72 million gallons per day from within the area of potential development is small. All pumping scenarios showed that about 81 percent of the ground-water pumpage was derived from regional flow that would have discharged to the Flint River downstream from the Lake Worth dam. The dominant ground-water-flow direction toward the Flint River was not changed and no induced recharge from the Flint River entered the potential-development area. Induced recharge from the undifferentiated overburden contributed to about 1.5 percent of the total volume pumped during the simulations.
Water resources data, Georgia, water year 1990
Water resources data for the 1990 water year for Georgia consists of records of stage, discharge, and water quality of streams; stage and contents of lakes and reservoirs; ground-water levels; and precipitation quality. This report contains discharge records of 117 gaging stations; stage for 28 gaging stations; stage and contents for 18 lakes and reservoirs; water quality for 128 continuing-record stations; peak stage and discharge only for 93 crest-stage partial-record stations and 8 miscellaneous sites; water levels of 25 observation wells; and water quality for 1 precipitation quality site. These data represent that part of the National Water Data System collected by the U.S. Geological Survey and cooperating State and Federal agencies in Georgia.
Preliminary geologic and hydrologic evaluation of a small watershed near Plains, Georgia
No abstract available.