Geology topics
Research about Georgia
Source-linked reports with geographic coverage including Georgia.
Impact of flow regulation and power plant effluents on the flow and temperature regimes of the Chattahoochee River - Atlanta to Whitesburg, Georgia
A calibrated and verified transient flow temperature model was used to evaluate the effects of flow regulation and powerplant loadings on the natural temperature regime of the Chattahoochee River in northeast Georgia. Estimates were made of both instantaneous and average natural temperatures in the river during an eight-day period in August 1976. Differences between the computed average natural temperature and an independent estimate of natural temperature based on observed equilibrium temperatures were less than 0.5°C. The combined thermal effects of flow regulation and powerplant effluents resulted in mean daily river temperatures downstream of the powerplants about equal to or less than computed mean natural temperatures during the period of interest. An independent analysis of historical river and air-temperature data, although considerably less accurate than model computations, provided substantially the same result. The range and rates of change of computed natural diurnal temperature fluctuations were considerably less than those presently observed (1976) in the river. The models also were used to simulate summer river temperatures using estimated year 2000 flow conditions and meteorologic data collected during 1976. Except during periods of peak water-supply demand, differences between computed year 2000 river temperatures and observed present-day temperatures were less than 2°C.
Erosion, sediment discharge, and channel morphology in the Upper Chattahoochee River basin, Georgia
Average annual rates of sheet erosion and sediment discharge were computed for several watersheds in the Upper Chattahoochee River basin in Georgia. Erosion yields ranged from about 900 to 6,000 tons per year per square mile in nine watersheds and were greatest where land use is largely agricultural or transitional. Suspended sediment yields from the same watershed ranged from about 300 to 800 tons per year per square mile and were greatest from urban areas and least from mostly forested watersheds. The impact of suspended sediment on stream quality was evaluated for 14 watersheds. In general, 60 percent or more of the total annual discharge of trace metals and phosphorus was contributed by suspended sediment. Yields of trace metals and nutrients in suspension were consistently greater in urban watersheds. Turbidity in basin streams increased geometrically with increasing concentrations of suspended sediment. (Woodard-USGS)
Magnitudes, nature, and effects of point and nonpoint discharges in the Chattahoochee River basin, Atlanta to West Point Dam, Georgia
On an average annual basis and during the storm period of March 12-15, 1976, nonpoint-source loads for most constituents were larger than point-source loads at the Whitesburg station, located on the Chattahoochee River about 40 miles downstream from Atlanta, GA. Most of the nonpoint-source constituent loads in the Atlanta to Whitesburg reach were from urban areas. Average annual point-source discharges accounted for about 50 percent of the dissolved nitrogen, total nitrogen, and total phosphorus loads and about 70 percent of the dissolved phosphorus loads at Whitesburg. During a low-flow period, June 1-2, 1977, five municipal point-sources contributed 63 percent of the ultimate biochemical oxygen demand, and 97 percent of the ammonium nitrogen loads at the Franklin station, at the upstream end of West Point Lake. Dissolved-oxygen concentrations of 4.1 to 5.0 milligrams per liter occurred in a 22-mile reach of the river downstream from Atlanta due about equally to nitrogenous and carbonaceous oxygen demands. The heat load from two thermoelectric powerplants caused a decrease in dissolved-oxygen concentration of about 0.2 milligrams per liter. Phytoplankton concentrations in West Point Lake, about 70 miles downstream from Atlanta, could exceed three million cells per millimeter during extended low-flow periods in the summer with present point-source phosphorus loads. (Woodard-USGS)
Effects of nutrients on algal growth in West Point Lake, Georgia
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Ground-water levels and quality data for Georgia, 1977
This report begins a publication format that will present annually both water-level and water-quality data. In this format the information is presented in two-page units: the left page includes text which summarizes the information for an area or subject and the right page consists of one or more illustrations. Daily mean water-level fluctuations and trends are shown in hydrographs for the previous year and fluctuations for the monthly mean water level the previous 10 years for selected observation wells in Georgia. The selected wells best illustrate the effects of changes in recharge and discharge in the various ground-water reservoirs in the State. A short narrative explains fluctuations and trends in each hydrograph.
Water resources data for Georgia, water year 1977
Water resources data for the 1977 water year for Georgia consists of records of stage, discharge, and water quality of streams; stage and contents of lakes and reservoirs. This report contains discharge records for 100 gaging stations; stage for 9 gaging stations; stage and contents for 16 lakes and reservoirs; water quality for 19 continuous stations and 110 periodic stations; and peak stage and discharge only for 151 crest-stage partial-record stations. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State and Federal agencies in Georgia.
Low-flow frequency of Georgia streams
This report contains analyses of low-flow data and tabulations of computed low-flow frequency for all stream sites in Georgia where suitable flow records have been collected. These include 134 continuous-record gaging stations and 102 partial-record gaging stations. Frequency records for gaging stations with short records have been adjusted where possible to more closely represent results that would have been obtained from longer records. Variations in time and place of low-flow characteristics, per unit of drainage area, are demonstrated. Low flows for 7 consecutive days with a 10-year recurrence interval vary from 0 to more than 1.0 cubic feet per second per square mile [(ft 3 /s)/mi 2 ]. In the Blue Ridge province in the northern part of the State, unit low flows range from 0.3 to 0.8 (ft 3 /s)/mi 2 ; in the Valley and Ridge province in the northwest they range from 0.05 to 0.04 (ft 3 /s)/mi 2 ; and in the Piedmont province they range from 0.1 to 1.1 (ft 3 /s)/mi 2 . There is a contrast in unit rates of low flow between the upper zone of the Coastal Plain where most flows are high, and the lower zone where most flows are low. Flows in the upper zone are in the range of 0.1 to 1.1 (ft 3 /s)/mi 2 , but in the lower zone only the largest streams have appreciable flow during low-flow periods.
A preliminary appraisal of the impact of agriculture on ground-water availability in southwest Georgia
Irrigated acreage in the study area in southwest Georgia increased from 130,000 acres in 1976 to 261,000 in 1977. Acreage irrigated entirely by ground water increased 85 percent for the same period. The largest quantity of ground water used for irrigation was in the Dougherty Plain district, where 92 percent of supplemental irrigation water comes from wells. In the Tifton Upland district, ground water is the source for only 16 percent of the irrigation water used. The major ground-water reservoir supplying the irrigation water is the principal artesian aquifer. The Dougherty Plain, because of the gently rolling land surface and large fields, is suitable for the use of large self-propelled center-pivot irrigation systems requiring 1,200 to 1,500 gallons per minute. The installed pump capacity of the irrigation systems in the Dougherty Plain using ground water was 1.8 billion gallons per day in 1977. The total amount of water pumped for irrigation in the Dougherty Plain in 1977 was more than 42 billion gallons, 30 billion gallons more than in 1976. This quantity could be considerably higher in 1978 as preparations were being made to irrigate more than 214,000 acres during the 1978 growing season. There were no concentrations of selected organic compounds or trace metals used in agricultural chemicals above the recommended limits for public consumption in water analyzed from 19 wells. However, concentrations of total nitrite plus nitrate ranged from 0.3 to 7.8 milligrams per liter in wells in the Dougherty Plain, and this could indicate that the downward percolation of water through sandy soils has carried soluble nitrate, a byproduct of fertilizer, into the ground-water reservoir.
Accuracy of selected land use and land cover maps in the Greater Atlanta region, Georgia
The land use and land cover maps at 1:100000 scale and at 1:24 000 scale in the Greater Atlanta Region were tested for accuracy. At 1:100 000 scale, 381 points were selected using a stratified systematic unalined sampling technique. Of these 381 points, 343 points or 90 percent were found to be correct. At 1:24 000 scale, 71 points were tested for accuracy. Of these 71 points, 62 points or 87 percent were found to be accurate. Confidence intervals were determined based on the assumption that the data exhibited a binomial distribution. With 95-percent confidence the accuracy of the 1:100 000-scale maps was between 87 and 93 percent, and the accuracy of the 1:24 000-scale maps was between 79 and 96 percent. The accuracy of the interpretations was consistent from category to category.
Aeroradioactivity map of parts of the Rome, Atlanta, and Phenix City 1° x 2° quadrangles, Georgia
No abstract available.
Aeromagnetic map of parts of the Rome, Atlanta, and Phenix City 1° x 2° quadrangles, Georgia
No abstract available.
Low-flow characteristics of the upper Flint River, Georgia
Low-flow data for locations on the main stem and for low-flow contributions of tributaries are analyzed and plotted as "flow profiles" for several different historical events on the upper Flint River in Georgia, for the reach from the vicinity of Griffin down to the vicinity of Culloden. Also shown as a flow profile are minimum average 7-day flows to be expected at the 10-year recurrence interval.
Preliminary report on Belair Exploratory Trench No. 10-76 near Augusta, Georgia
The Belair Exploratory Trench #10-76 was dug in October,1976, for the purpose of testing the conclusions of Prowell, O'Connor, and Rubin, 1975, and O'Connor and Prowell, 1976, concerning the time of latest movement along the Belair fault zone. The trench site is located 800 meters (2600 ft.) S27°W of the old Belair railroad station on U.S. Route 1 & 78 (see inset on Plate 1) in the southernmost clay pit of the Georgia Vitrified Brick and Clay Company. The trench was oriented almost nor-mal to the strike of the Belair fault zone (N27°E) about 100 meters (330 ft.) south of the trench exposure reported by Prowell, O'Connor, and Rubin, 1975. In this report, we are maintaining the terminology of Prowell, O'Connor, and Rubin, 1975, in defining the main fault as the fault that juxtaposes the crystalline phyllites and the Coastal Plain sediments (Plate 1 - at meter 106). Similarly, we refer to the eastside of the Belair fault zone as the upblock and the west side as the downblock.
Ground-water resources and geology of Colquitt County, Georgia
Limestone beds of Eocene, Oligocene, and lower Miocene age, called the principal artesian aquifer, are the chief source of ground water for Colquitt County. Because streams are small, undependable and relatively inaccessible to most users, ground water is the most important source for increased industrial and agricultural water use. Southeast of Moultrie the principal artesian aquifer is very productive, and has transmissivity in excess of 145,000 feet squared per day (13,500 meters squared per day). A structural or paleogeographic feature called the Suwannee strait traverses the county from near the southwest corner to the northeast corner. In this strait, limestone in the principal artesian aquifer is partly replaced by fine-grained clastic sediment, impairing transmissivity and making wells hard to construct. Transmissivity is much lower northwest of the strait than it is southeast, probably because of facies changes in the aquifer. In the belt of the hypothesized Ochlockonee fault, water containing greater-than-usual concentrations of dissolved solids is produced. This anomaly could be the result of the fault having acted as a conduit when the vertical hydraulic gradient was upward from a deeper aquifer, or be the result of the movement of ground water from a sulfate-rich source in the sediments of the Suwannee strait. In south-central Colquitt County, clay-capped permeable beds extending above potentiometric surfaces create conditions favorable for breathing wells. Predominantly clastic beds of Miocene age overlie the Suwannee Limestone. These beds have a transmissivity of about 2,280 feet squared per day (215 meters squared per day), but they are of comparatively little importance because larger yields can be obtained from the underlying principal artesian aquifer. Moreover, wells are difficult to construct in the poorly consolidated clastic sediments, and water from these shallow beds is likely to be depleted during droughts. The ground water is generally hard, but is otherwise of good quality. One exception is near the hypothesized Ochlockonee fault where water contains higher-than-usual concentrations of various ions, especially sulfate. Another exception occurs along the axis of the Suwannee strait where clay minerals in the channel facies may soften the water by ion exchange.
Water resources data for Georgia, water year 1976
Water resources data for the 1976 water year for Georgia consists of records of stage, discharge, and water quality of streams; stage and contents of lakes and reservoirs. This report contains discharge records for 99 gaging stations; stage for 9 gaging stations, stage and contents for 16 lakes and reservoirs; water quality for 20 continuous stations and 108 periodic stations. Also included are 115 crest-stage stations, 3 miscellaneous discharge measurements and miscellaneous sediment samples at 24 gaging stations. Records for a few pertinent stations in bordering States are also included in this report. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State and Federal agencies in Georgia.
Digital model analysis of the principal artesian aquifer, Savannah, Georgia area
A digital model of the principal artesian aquifer has been developed for the Savannah, Georgia, area. The model simulates the response of the aquifer system to various hydrologic stresses. Model results of the water levels and water-level changes are shown on maps. Computations may be extended in time, indicating changes in pumpage were applied to the system and probable results calculated. Drawdown or water-level differences were computed, showing comparisons of different water management alternatives. (Woodard-USGS)
Preliminary flood-frequency relations for urban streams, Metropolitan Atlanta, Georgia
A method is presented for estimating the magnitude and frequency of floods for urban streams in metropolitan Atlanta. The method is based on adjustments to the natural stream flood-frequency and rainfall-frequency characteristics of the local area as defined by urban flood studies in other areas. The effects of urbanization on flood-peak runoff are estimated from the percentage of drainage basin that is impervious and the percentage of drainage area served by storm sewers. Equations are presented for estimating the 2-, 5-, 10-, 25-, 50-, and 100-year flood peak discharges for basin sizes from 0.5 to 100 square miles in the Atlanta metro area.