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Source-linked reports with geographic coverage including Georgia.
Water Resources Data for Georgia, Water Year 1986
This volume of the annual hydrologic data report of Georgia is one of a series of annual reports that document hydrologic data gathered from the U.S. Geological Survey's surface- and ground-water data-collection networks in each State, Puerto Rico, and the Trust Territories. These records of streamflow, ground-water levels, and quality of water provide the hydrologic information needed by State, local, and Federal agencies, and the private sector for developing and managing our Nation's land and water resources. Hydrologic data for Georgia are contained in 1 volume.
Movement and fate of ethylene dibromide (EDB) in ground water in Seminole County, Georgia
An investigation to assess the movement and fate of ethylene dibromide (EDB) in the Upper Floridan aquifer (formerly the principal artesian aquifer) was conducted, because a previous investigation conducted in August 1983, had found EDB contamination of the aquifer in about a 4 sq mi area in central Seminole County, Georgia. Analyses of water from wells resampled in June 1985 indicate that EDB was present in the groundwater 2 yr after last being applied as a soil fumigant. The investigation revealed that groundwater recharge and irrigation pumping between August 1983 and June 1985 did not substantially change the areal extent of EDB in the Upper Floridan aquifer but concentrations of EDB seem to be declining. The highest concentrations again were found in two irrigation wells near Buck Hole, a sinkhole in a swampy depression in central Seminole County. EDB concentrations in these two wells ranged from 1.5 to 13 micrograms/L. Samples from two of three wells in the residuum near Buck Hole also had detectable concentrations of EDB. The presence of EDB in water samples from wells tapping the residuum and wells tapping the Upper Floridan aquifer indicates that agriculturally applied EDB has moved downward from the surface soils through the residuum and into the aquifer. Results of aquifer tests conducted in a similar geohydrologic setting suggest that local pumping from the highly transmissive aquifer may accelerate downward movement of water and EDB. Potentiometric surface maps of the Upper Floridan aquifer indicate that east of Fishpond Drain, where the highest concentrations of EDB were detected, the direction of groundwater flow and the direction of potential EDB transport generally is south-southeasterly. However, the movement of an EDB plume from the area of relatively high concentrations near Buck Hole along inferred groundwater flow lines was not detected. (Author 's abstract)
Hydrogeology, chemical quality, and availability of ground water in the Upper Floridan aquifer, Albany area, Georgia
Large withdrawals of groundwater in the 1500 sq mi Albany area of southwestern Georgia have lowered water levels in deep aquifers as much as 140 ft. This study was conducted to evaluate the development potential of the shallow Upper Floridan aquifer as an alternate source of groundwater, especially for public supply. The Upper Floridan stores and transmits large quantities of water, mainly in a zone of high permeability in the lower part of the aquifer. The transmissivity of the aquifer ranges from < 10,000 sq ft/day northwest of Albany, to as much as 150 ,000 sq ft/day south and southeast of Albany. Twenty-eight years of agricultural and industrial pumping has not produced a long-term decline of the water level in the Upper Floridan; the aquifer system remains at equilibrium. The Upper Floridan yields hard, calcium bicarbonate-type water but concentrations do not exceed State drinking water standards. In most of the study area , contaminants applied to or spilled on the land surface eventually can be expected to percolate through the overburden and reach the aquifer. Thus, it is important that wells be sited away from areas that have been used for the storage and disposal of potential contaminants and, probably to a lesser extent, the application of agricultural chemicals. In the area of greatest development potential east of the Flint River, wells may penetrate major groundwater conduits. By limiting drawdown during well development and during production, the likelihood of causing sinkholes to form can be minimized. Closed depressions, or sinks, throughout the Dougherty Plain probably are unsuitable as well sites, because (1) they are subject to flooding, (2) they collect water from upgradient areas and could concentrate potential contaminants, (3) water probably percolates through their bottoms and could transport contaminants into the aquifer, and (4) the depressions may overlie limestone cavities filled with sand or clay that could interfere with well yield, development, and production. (Author 's abstract)
Simulation of flood hydrographs for Georgia streams
Flood hydrographs are needed for the design of many highway drainage structures and embankments. A method for simulating these flood hydrographs at ungaged sites in Georgia is presented in this report. The O'Donnell method was used to compute unit hydrographs and lagtimes for 355 floods at 80 gaging stations. An average unit hydrograph and an average lagtime were computed for each station. These average unit hydrographs were transformed to unit hydrographs having durations of one-fourth, one-third, one-half, and three-fourths lagtime, then reduced to dimensionless terms by dividing the time by lagtime and the discharge by peak discharge. Hydrographs were simulated for these 355 floods and their widths were compared with the widths of the observed hydrographs at 50 and 75 percent of peak flow. The dimensionless hydrograph based on one-half lagtime duration provided the best fit of the observed data. Multiple regression analysis was then used to define relations between lagtime and certain physical basin characteristics; of these characteristics, drainage area and slope were found to be significant for the rural-stream equations and drainage area, slope, and impervious area were found to be significant for the Atlanta urban-stream equation. A hydrograph can be simulated from the dimensionless hydrograph, the peak discharge of a specific recurrence interval, and the lagtime obtained from regression equations for any site in Georgia having a drainage area of less than 500 square miles. For simulating hydrographs at sites having basins larger than 500 square miles, the U.S. Geological Survey computer model CONROUT can be used. This model routes streamflow from an upstream channel location to a user-defined location downstream. The product of CONROUT is a simulated discharge hydrograph for the downstream site that has a peak discharge of a specific recurrence interval.
Water resources activities, Georgia District, 1985
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Ground-water data for Georgia, 1985
Continuous water level records from 146 wells and water level measurements from an additional 1,100 wells in Georgia during 1985 provide the basic data for this report. Hydrographs for selected wells illustrate the effects that changes in recharge and discharge have had on the groundwater reservoirs in the State. Daily mean water levels are shown in hydrographs for 1985. Monthly mean water levels are shown for the 10-year period 1976-86. During 1985, annual mean water levels were generally lower than in 1984, and ranged from 11.4 feet lower to 0.6 feet higher. Much of the decline can be attributed to below-normal precipitation from mid-1984 to mid-1985. Water quality samples also are collected periodically throughout Georgia and analyzed as part of areal and regional groundwater studies. Along the coast, the chloride concentration in the Floridan aquifer system generally remained stable in the Savannah and Brunswick areas. (USGS)
Water resources data for Georgia, water year 1985
Water resources data for the 1985 water year for Georgia consists of records of stage, discharge, and water quality of streams; stage and contents of lakes and reservoirs; and ground-water levels. This report contains discharge records of 109 gaging stations; stage for 11 gaging stations; stage and contents for 18 lakes and reservoirs; water quality for 109 continuing-record stations; peak stage and discharge only for 121 crest-stage partial-record stations and 6 miscellaneous sites; and water levels of 27 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.
Simulation of flood hydrographs for Georgia streams
Flood hydrographs are needed for the design of many highway drainage structures and embankments. A method for simulating these flood hydrographs at ungaged sites in Georgia is presented in this report. The O'Donnell method was used to compute unit hydrographs and lagtimes for 355 floods at 80 gaging stations. An average unit hydrograph and an average lagtime were computed for each station. These average unit hydrographs were transformed to unit hydrographs having durations of one-fourth, one-third, one-half, and three-fourths lagtime, then reduced to dimensionless terms by dividing the time by lagtime and the discharge by peak discharge. Hydrographs were simulated for these 355 floods and their widths were compared with the widths of the observed hydrographs at 50 and 75 percent of peak flow. The dimensionless hydrograph based on one-half lagtime duration provided the best fit of the observed data. Multiple-regression analysis was then used to define relations between lagtime and certain physical basin characteristics, of which drainage area and slope were found to be significant for the rural-stream equations, and drainage area, slope, and impervious area were found to be significant for the Atlanta urban-stream equation. A hydrograph can be simulated from the dimensionless hydrograph, the peak discharge of a specific recurrence interval, and the lagtime obtained from regression equations for any site with less than a 500 square mile drainage area in Georgia. For simulating hydrographs at sites with basins larger than 500 square miles, the U.S. Geological Survey computer model CONROUT can be used. This model routes streamflow from an upstream channel location to a user-defined location downstream. The product of CONROUT is a simulated discharge hydrograph for the downstream site, which has a peak discharge of a specific recurrence interval. The diffusion-analogy routing method with single linearization was used in this study.
Occurrence and availability of ground water in the Athens region, northeastern Georgia
A study was conducted to assess the occurrence and availability of groundwater in the crystalline rocks of the Piedmont area in northeastern Georgia and to determine whether groundwater is a viable alternative or supplemental source for industrial, public and private supplies. The area is underlain by a variety of metamorphic and igneous rocks. The quantity of water that a rock unit can supply to wells is determined by the number, capacity, and interconnection of the secondary openings. Of an estimated 10,000 successful wells drilled in the Athens Region, 972 wells are reported by drilling contractors to supply from 20 to 300 gal/min. Studies of well sites revealed that high yielding wells can be developed only where the water bearing units have undergone significant increases in secondary permeability. This occurs mainly in association with (1) contact zones between rock units of contrasting character, (2) contact zones within multilayered rock units, (3) fault zones, (4) stress-relief fractures, and (5) shear zones. Groundwater may be a viable alternative or supplemental source for industrial, public, and private supplies in much of the Athens Region. In 1980, groundwater made up 38% (18 million gal/day) of the total water used in the area. Yields of 20 to more than 200 gal/min are obtained from wells throughout most of the region, and the water is generally of good chemical quality and is suitable for drinking and many other uses. Concentrations of dissolved constituents are fairly consistent throughout the area. Except for iron, manganese, and fluoride, dissolved constituents rarely exceed drinking water standards. (Lantz-PTT)
Low-flow profiles of the upper Ocmulgee and Flint rivers in Georgia
This report provides low-flow information for use in evaluating the capacity of streams to supply withdrawals or to accept waste loads from potential new industries without exceeding the limits of State water-quality standards. The report is the first phase of a study of all stream basins north of the Fall Line in Georgia. It covers the Piedmont part if the Ocmulgee and Flint River basins. The low-flow characteristic presented is the minimum average flow for 7 consecutive days with a 10-year recurrence interval. The data are presented graphically as low-flow profiles (low flow as a function of distance along a stream channel) and as drainage-area profiles (drainage area as a function of distance along a stream channel). Low-flow profiles were constructed by interpolation or extrapolation from points of known low-flow data. Low-flow profiles are included for all stream reaches where low-flow data of sufficient accuracy are available to justify computation of the profiles. Drainage-area profiles are included for all stream basins larger than 5 sq mi. Flow records were not adjusted for diversions or other factors that cause measured flows to represent other than natural flow conditions. Profiles for 7-day minimum flows are omitted for stream reaches where natural flow is known to be significantly altered. (Author 's abstract)
Verification of regression equations for estimating flood magnitudes for selected frequencies on small natural streams in Georgia
In 1976 the U.S. Geological Survey, in cooperation with the Georgia Department of Transportation, began a program to monitor small natural streams in Georgia to verify the accuracy of the flood frequency estimating equations for the five flood frequency regions that were published in a previous study. Data collection consisted of obtaining an additional 10 yr of annual peak flow records at 24 gaging stations and establishing and collecting annual peak flow records at 15 additional gaging sites in areas of the State where data were unavailable. Data also were collected for an additional 10 yr at four gaging stations that were converted to continuous record gaging stations in 1976. The flood frequency equations were verified by comparing the observed and regression equation estimated discharges for the 2-, 25-, and 100-yr floods: (1) for the 28 gaging stations continued an additional 10 yr; (2) for the 15 gaging stations that have about 10 yr of record where data were unavailable; and (3) for all gaging stations on drainage areas of < 50 sq mi for which data were available in all five flood frequency regions. The rainfall-runoff model simulated discharges from the previous study also were verified by comparisons of the observed and the rainfall-runoff model simulated discharges for the 2-, 25-, and 100-yr floods for gaging stations calibrated in the previous study. These comparisons, based on student 's t-test statistics at the 0.05 level of significance, indicated that all the flood frequency equations computed in the previous study are valid and unbiased except for Regions 2 and 3, where the equations appear to be slightly biased. The comparison of the discharges simulated by the rainfall-runoff model with the observed discharges for the gaging stations that have 20 yr of record were unbiased, but simulated discharges for stations having 10 yr of record were biased, probably because of ' loss of variance ' in the averaging procedures of the rainfall-runoff model and the short length of record. The flood-frequency estimating equations computed in the previous study have been verified and are considered to be valid for natural streams in Georgia that have drainage areas of 0.1 to 20 sq mi. (Author 's abstract)
Maps showing mines, prospects, and mineral sites in the Tray Mountain Roadless Area and vicinity, Northern Georgia
The Tray Mountain Roadless Area, a 36,300-acre tract in the Chattahoochee National Forest, northeastern Georgia, lies within the Blue Redge physiographic province. The roadless area is composed of Precambrian(?)-age metamorphic rocks from two tectonic units, the Hayesville thrust sheet and the "Helen belt" (Nelson, 1982) (fig. 1). The Hayesville thrust sheet consists mostly of biotite gneiss and schist, fine-grained biotite-feldspar gneiss, metasandstone, quartzite, and amphibolite; ultramafic bodies, some granitic gneiss, and small pegmatites are also present. The Helen belt contains mostly metagraywacke, metasandstone, quartzite, graphite schist, amphibolite, some ultramafic bodies, and granitic gneiss. Two "gold belts" and an area of mineralization associated with ultramafic rocks are on lands adjacent to the roadless area. Mining within the roadless area has not been extensive, and there is no current mineral activity in the surrounding region.
Aeromagnetic map and analysis of aeromagnetic and aeroradioactivity data in the Blood Mountain, Chattahoochee, and Tray Mountain Roadless Areas, northern Georgia
The data for the aerornagnetic map of the Blood Mountain, Chattahoochee, and Tray Mountain Roadless Areas and vicinity were compiled from two separate airborne surveys {U.S. Geological Survey, 1977, 1981) produced in cooperation with the State of Georgia. These surveys were flown by fixed - wing aircraft in 1976 and 1981 at 500 ft (150 m) above mean terrain along rarallel flight lines oriented northwest-southeast. Flight-line spacing is 0.5 mi (0.8 km} for the 1981 survey, which covers the major part of the map, and l mi (1.6 km) for the 1976 survey, which covers the southeast corner of the map. The 1976 survey was adjusted to the magnetic level of the 1981 survey and recontoured where the surveys join. The International Geomagnetic Reference Field (Barraclough and Fabiano, 1975) has been removed from the data of each survey.
Sediment data for Georgia streams, water years 1958-82
Sediment data have been collected regularly in Georgia by the U.S. Geological Survey since 1957. The data were collected in cooperation with a number of State and Federal agencies. The frequency of data collection varied and several sampling methodologies were used. This report presents suspended-sediment-concentration data for 179 sites, suspended-sediment particle-size for 16 sites, and bed-material particle-size data for 19 sites collected from October 1957 to September 1982. (USGS)