Search USGS⌕ Search

Geology topics

Research about Tennessee

Source-linked reports with geographic coverage including Tennessee.

At least 109 records · Page 6Linked to original sources
USGS2010

Suspended-sediment concentration regimes in Tennessee biological reference streams

Suspended-sediment-concentration (SSC) regimes of five biological reference streams in Tennessee were characterized from 15-minute SSC records spanning 1 to 4 water years (October 1 through September 30) between 2004 and 2008. These streams represent least disturbed conditions for their respective ecoregions and have exceptional biodiversity in terms of fish or aquatic invertebrates. SSC regimes in streams, when plotted in terms of duration above a given SSC at a given annual frequency such as the annual maximum or the annual tenth longest duration, can be compared directly to published biological impairment thresholds derived from experimental trials. Based on such comparison, the SSC regimes of all five reference streams reached published impairment thresholds at least 10 times per water year for all years of record. The results suggest that the published impairment thresholds are not directly applicable to streams in Tennessee and, by extension, the southeastern United States.

Tennessee↗
USGS2008

Relating streamflow characteristics to specialized insectivores in the Tennessee River Valley: a regional approach

Analysis of hydrologic time series and fish community data across the Tennessee River Valley identified three hydrologic metrics essential to habitat suitability and food availability for insectivorous fish communities in streams of the Tennessee River Valley: constancy (flow stability or temporal invariance), frequency of moderate flooding (frequency of habitat disturbance), and rate of streamflow recession. Initial datasets included 1100 fish community sites and 300 streamgages. Reduction of these datasets to sites with coexisting data yielded 33 sites with streamflow and fish community data for analysis. Identification of critical hydrologic metrics was completed using a multivariate correlation procedure that maximizes the rank correlation between the hydrologic metrics and fish community resemblance matrices. Quantile regression was used to define thresholds of potential ranges of insectivore scores for given values of the hydrologic metrics. Increased values of constancy and insectivore scores were positively correlated. Constancy of streamflow maintains wetted perimeter, which is important for providing habitat for fish spawning and increased surface area for invertebrate colonization and reproduction. Site scores for insectivorous fish increased as the frequency of moderate flooding (3 times the median annual streamflow) decreased, suggesting that insectivorous fish communities respond positively to less frequent disturbance and a more stable habitat. Increased streamflow recession rates were associated with decreased insectivore scores. Increased streamflow recession can strand fish in pools and other areas that are disconnected from flowing water and remove invertebrates as food sources that were suspended during high-streamflow events.

Tennessee↗
USGS2008

Age-class structure and variability of two populations of the bluemask darter etheostoma (Doration) sp.

The bluemask darter Etheostoma ( Doration ) sp. is an endangered fish endemic to the upper Caney Fork system in the Cumberland River drainage in central Tennessee. Darters ( Etheostoma spp.) are typically short-lived and exhibit rapid growth that quickly decreases with age. Consequently, estimating age of darters from length-frequency distributions can be difficult and subjective. We used a nonparametric kernel density estimator to reduce subjectivity in estimating ages of bluemask darters. Data were collected from a total of 2926 bluemask darters from the Collins River throughout three growing seasons. Additionally, data were collected from 842 bluemask darters from the Rocky River during one growing season. Analysis of length-frequencies indicated the presence of four age classes in both rivers. In each river, the majority of the population was comprised of fish <3 y old. Some age-one individuals were sexually mature, but the majority of the reproductive population was comprised of older fish. Differences in age-class structure among years reflected variable year-class strength in the Collins River that seemed related to summer discharge. Male and female growth rates differed significantly (P < 0.05); males were typically larger than females of the same age after the first growing season and the majority of age-three individuals were males. Growth rates in the Collins and Rocky Rivers were similar for each sex (P > 0.05). In both rivers, females were more abundant than males.

Tennessee↗
USGS2008

Estimated use of water in the Upper Duck River watershed, central Tennessee, and water-demand projections through 2030

Future municipal water demand was estimated for the Bedford, Coffee, Marshall, and Maury-southern Williamson water-service areas in the upper Duck River watershed in central Tennessee through 2030. The Duck River, a primary source of municipal water, provided a total of 24.3 million gallons per day (Mgal/d) or 92 percent of the total water use in the study area during 2000. Municipal water use increased 46 percent from 1981 to 2000 (from 18.0 to 26.3 Mgal/d). Water demand for municipal use is expected to continue to increase through 2030 because of the recent intensive and anticipated growth in the residential and commercial sectors. Constant-rate models were used to estimate future municipal water demand. Data on residential and nonresidential billing accounts and estimates of public use and losses were used to calibrate the models. Two watershed scenarios for each water-supply system that depends on the Duck River for supply were simulated. Scenario 1 considered monthly water demand during typical weather conditions as represented by monthly per account use during 2003 and a rate of growth in customer accounts from 1999 to 2003. Results showed that total municipal water use could increase about 104 percent to 51 Mgal/d by 2030, residential water use could increase about 140 percent to 24 Mgal/d, nonresidential water use could increase about 110 percent to 17 Mgal/d, and public use and losses could increase about 83 percent to 11 Mgal/d. Scenario 2 considered monthly water demand during drought conditions as represented by monthly per account use during 2000 and recent growth in customer accounts from 1999 to 2003 or, for selected water-supply systems, an increasing rate of growth. Results showed that total municipal water use could increase about 120 percent to 55 Mgal/d, residential water use could increase about 160 percent to 26 Mgal/d, nonresidential water use could increase about 122 percent to 18 Mgal/d, and public use and losses could double and increase to 12 Mgal/d. For both scenarios the model assumed that the Duck River would supply all future surface-water needs in the study area, that ground-water resources would be sufficient to meet growing demands of the water-supply systems that depend on ground water, and that the amount of surface water sold to water-supply systems primarily dependent on ground water would remain the same through 2030.

Tennessee↗
USGS2007

Variability in measured bedload-transport rates

Variability in bedload-transport rates during constant water discharge is an inherent part of the bedload-transport process. Although this variability has been measured extensively in the laboratory, similar information generally is not available from field measurements. During a four-day period of nearly constant water discharge, four sets of consecutively collected bedload samples, ranging from 43 to 120 samples, were obtained at the same cross channel location using a standard 65-pound Helley-Smith bedload sampler. When the measured transport rates are converted to dimensionless rates and plotted as cumulative frequency distributions, they show good agreement with a theoretical probability distribution function of rates derived for the case of ripples on dunes. The distributions show that during constant water discharge individual measured rates at a fixed point vary from near zero to four times the mean rate, and 60 percent of the sampled rates will be less than the mean. Because of the large variation in transport rates that occurs at every location in the cross section, many observations are required to establish an accurate estimate of the mean rate at any given location.

Tennessee↗
USGS2007

Soil gas screening for chlorinated solvents at three contaminated karst sites in Tennessee

Soil gas was sampled using active sampling techniques and passive collectors at three sites in Tennessee to evaluate the effectiveness of these techniques for locating chlorinated solvent sources and flowpaths in karst aquifers. Actively collected soil gas samples were analyzed in the field with a portable gas chromatograph, and the passive soil gas collectors were analyzed in the lab with gas chromatography/mass spectrometry. Results of the sampling indicate that the effectiveness of both techniques is highly dependent on the distribution of the contaminants in the subsurface, the geomorphic and hydrogeologic characteristics of the site, and, in one case, on seasonal conditions. Both active and passive techniques identified areas of elevated subsurface chlorinated solvent concentrations at a landfill site where contamination remains concentrated in the regolith. Neither technique detected chlorinated solvents known to be moving in the bedrock at a manufacturing site characterized by thick regolith and an absence of surficial karst features. Passive soil gas sampling had varied success detecting flowpaths for chloroform in the bedrock at a train derailment site characterized by shallow regolith and abundant surficial karst features. At the train derailment site, delineation of the contaminant flowpath through passive soil gas sampling was stronger and more detailed under Winter conditions than summer.

Tennessee↗
USGS2006

Integrating human impacts and ecological integrity into a risk-based protocol for conservation planning

Conservation planning aims to protect biodiversity by sustainng the natural physical, chemical, and biological processes within representative ecosystems. Often data to measure these components are inadequate or unavailable. The impact of human activities on ecosystem processes complicates integrity assessments and might alter ecosystem organization at multiple spatial scales. Freshwater conservation targets, such as populations and communities, are influenced by both intrinsic aquatic properties and the surrounding landscape, and locally collected data might not accurately reflect potential impacts. We suggest that changes in five major biotic drivers—energy sources, physical habitat, flow regime, water quality, and biotic interactions—might be used as surrogates to inform conservation planners of the ecological integrity of freshwater ecosystems. Threats to freshwater systems might be evaluated based on their impact to these drivers to provide an overview of potential risk to conservation targets. We developed a risk-based protocol, the Ecological Risk Index (ERI), to identify watersheds with least/most risk to conservation targets. Our protocol combines risk-based components, specifically the frequency and severity of human-induced stressors, with biotic drivers and mappable land- and water-use data to provide a summary of relative risk to watersheds. We illustrate application of our protocol with a case study of the upper Tennessee River basin, USA. Differences in risk patterns among the major drainages in the basin reflect dominant land uses, such as mining and agriculture. A principal components analysis showed that localized, moderately severe threats accounted for most of the threat composition differences among our watersheds. We also found that the relative importance of threats is sensitive to the spatial grain of the analysis. Our case study demonstrates that the ERI is useful for evaluating the frequency and severity of ecosystemwide risk, which can inform local and regional conservation planning.

Tennessee↗
USGS2006

Hydraulics of sheetlike solution cavities

The sheetlike solution cavities that supply water to most wells in central Tennessee are 100 to 2,500 feet wide and less than 0.2 inch high. These dimensions have a scale similar to those in Hele-Shaw models. Both logical and mathematical evidence indicate laminar ground-water flow, except close to pumping wells. The Theis nonequilibrium formula may be used to analyze aquifer-test data and to calculate significant values for transmissivity and storage. The Navier-Stokes equation and the Darcy equation for steady-state conditions may be used to estimate cavity dimensions.

Tennessee↗
USGS2005

Tree mortality, canopy turnover, and woody detritus in old cove forests of the southern Appalachians

A long-term study of tree mortality, canopy turnover, and coarse woody detritus inputs was conducted in cove forests of the Great Smoky Mountains, Tennessee, USA. Seven old-growth stands were studied over a 10-yr period using 0.6–1.0 ha plots. Annual mortality of trees >10 cm dbh was 0.5–1.4% among stands (mean 0.7%). The highest mortality rate among canopy trees was exhibited by trees >80 cm dbh. An increase in mortality rate with canopy tree size was evident for two (Tsuga canadensis and Acer saccharum) of the three most abundant species in the forest. The increase in mortality with tree size had implications for canopy turnover and detritus input. Gap disturbance frequency was estimated at 0.008–0.019 forest area/yr, giving a return interval of ∼130 yr or less. Standing death was the most common mode of mortality (59%). Annual rates of snag formation were 1.4 snags/ha for trees >10 cm dbh and 0.4 snags/ha for trees >50 cm dbh. The density of large snags (>50 cm dbh) was 5 snags/ha. Snags accounted for 8% of the total standing tree basal area and 23% of the coarse woody detritus mass (total of 48 Mg/ ha). The mean annual rate of coarse woody detritus input was 3.0 Mg/ha. A decay rate constant was estimated at 0.07, yielding a detritus half-life of 10 yr. Although mean mortality rates and canopy turnover in old cove forests were moderate in comparison with other old forests of eastern North America, input and accumulation of coarse woody detritus were high for the region. This resulted, in part, from the relatively large sizes attained by canopy trees and the fact that larger trees tended to suffer higher mortality. In comparison to forests worldwide, rates of mortality, canopy gap formation, and decay of coarse woody detritus were intermediate.

Tennessee↗
USGS2004

Hydrogeology and ground-water-flow simulation in the former airfield area of Naval Support Activity Mid-South, Millington, Tennessee

Naval Support Activity Mid-South is a Department of the Navy base located in Millington, Tennessee. The facility was home to the Naval Aviation Technical Training Center from 1943 until 1996. As part of the Base Closure and Realignment Act of 1990, the primary training mission of the facility was realigned and most of the northern part of the base, referred to as the Northside and consisting primarily of an airfield, was transferred to the city of Millington in January 2000. During environmental investigations at the base, plumes of dissolved chlorinated solvents resulting from past aircraft maintenance and training operations were identified in shallow ground water beneath the airfield area. The airfield area containing the plumes has been designated as Area of Concern (AOC) A. Chlorinated solvents, primarily trichloroethene (TCE), are the principal contaminants in ground water at AOC A, with TCE identified in concentrations as high as 4,400 micrograms per liter. The nature and extent of these plumes at AOC A were addressed during a Resource Conservation and Recovery Act Facility Investigation, and selected options for remediation currently are being implemented under a corrective action program. As part of these efforts, the U.S. Geological Survey (USGS) is working with the Navy and its consultants to study the hydrogeologic framework of the base and surrounding area, with a focus on AOC A. Since 1997, investigations at and near the facility have produced data prompting revisions and additions to information published that year in two USGS reports. The updates are presented in this report and consist primarily of (1) refinements to selected hydrogeologic maps presented in the 1997 reports, on the basis of data collected from new wells at on- and off-base locations, (2) additional hydraulic-conductivity data collected for the alluvial-fluvial deposits aquifer at AOC A, and (3) construction of a potentiometric-surface map of the shallow aquifer for the former part of the Naval Support Activity Mid-South Northside and adjacent off-base locations for February and March 2000 water-level conditions. Additionally, a numerical ground-water-flow model of AOC A was developed and calibrated to the February and March 2000 potentiometric-surface data, the results of which also are presented in this report. Particle-tracking simulations were used with the model to simulate ground-water-flow paths from two sites suspected of being contaminant source areas at AOC A. The flow paths indicated by the particle tracking simulations agree reasonably well with maps of the interpreted extents of TCE plumes. The time-of-travel plots show that advective travel times from the two suspected source areas to the model boundary are controlled by relative proximities of the source areas to a part of AOC A identified from investigations and simulated with the model as having the highest horizontal hydraulic conductivity.

Tennessee↗
USGS2003

Development of hardwood seed zones for Tennessee using a geographic information system

For species that have no or limited information on genetic variation and adaptability to nonnative sites, there is a need for seed collection guidelines based on biological, climatological, and/or geographical criteria. Twenty-eight hardwood species are currently grown for reforestation purposes at the East Tennessee State Nursery. The majority of these species have had no genetic testing to define guidelines for seed collection location and can be distributed to sites that have a very different environment than that of seed origin(s). Poor survival and/or growth may result if seedlings are not adapted to environmental conditions at the planting location. To address this problem, 30 yr of Tennessee county precipitation and minimum temperature data were analyzed and grouped using a centroid hierarchical cluster analysis. The weather data and elevational data were entered into a Geographic Information System (GIS) and separately layered over Bailey's Ecoregions to develop a seed zone system for Tennessee. The seed zones can be used as a practical guideline for collecting seeds to ensure that the resulting seedlings will be adapted to planting environments.

Tennessee↗
USGS2003

Lithology and shear-wave velocity in Memphis, Tennessee

We have derived a new three-dimensional model of the lithologic structure beneath the city of Memphis , Tennessee , and examined its correlation with measured shear - wave velocity profiles. The correlation is sufficiently high that the better-constrained lithologic model may be used as a proxy for shear - wave velocities, which are required to calculate site-amplification for new seismic hazard maps for Memphis . The lithologic model and its uncertainties are derived from over 1200 newly compiled well and boring logs, some sampling to 500 m depth, and a moving-least-squares algorithm. Seventy-six new shear - wave velocity profiles have been measured and used for this study, most sampling to 30 m depth or less. All log and velocity observations are publicly available via new web sites.

Tennessee↗
USGS2003

Flood-frequency prediction methods for unregulated streams of Tennessee, 2000

Up-to-date flood-frequency prediction methods for unregulated, ungaged rivers and streams of Tennessee have been developed. Prediction methods include the regional-regression method and the newer region-of-influence method. The prediction methods were developed using stream-gage records from unregulated streams draining basins having from 1 percent to about 30 percent total impervious area. These methods, however, should not be used in heavily developed or storm-sewered basins with impervious areas greater than 10 percent. The methods can be used to estimate 2-, 5-, 10-, 25-, 50-, 100-, and 500-year recurrence-interval floods of most unregulated rural streams in Tennessee. A computer application was developed that automates the calculation of flood frequency for unregulated, ungaged rivers and streams of Tennessee. Regional-regression equations were derived by using both single-variable and multivariable regional-regression analysis. Contributing drainage area is the explanatory variable used in the single-variable equations. Contributing drainage area, main-channel slope, and a climate factor are the explanatory variables used in the multivariable equations. Deleted-residual standard error for the single-variable equations ranged from 32 to 65 percent. Deleted-residual standard error for the multivariable equations ranged from 31 to 63 percent. These equations are included in the computer application to allow easy comparison of results produced by the different methods. The region-of-influence method calculates multivariable regression equations for each ungaged site and recurrence interval using basin characteristics from 60 similar sites selected from the study area. Explanatory variables that may be used in regression equations computed by the region-of-influence method include contributing drainage area, main-channel slope, a climate factor, and a physiographic-region factor. Deleted-residual standard error for the region-of-influence method tended to be only slightly smaller than those for the regional-regression method and ranged from 27 to 62 percent.

Tennessee↗
USGS2002

Hydrogeology and ground-water-flow simulation of the Cave Springs area, Hixson, Tennessee

The ground-water resource in the Cave Springs area is used by the Hixson Utility District as a water supply and is one of the more heavily stressed in the Valley and Ridge Physiographic Province. In 1999, ground-water withdrawals by the Hixson Utility District averaged about 6.4 million gallons per day (Mgal/d) from two pumping centers. The Hixson Utility District has historically withdrawn about 5.8 Mgal/d from wells at Cave Springs. In 1995 to meet increasing demand, an additional well field was developed at Walkers Corner, located about 3 miles northeast of Cave Springs. From 1995 through 2000, pumping from the first production well at Walkers Corner averaged about 1.8 Mgal/d. A second production well at Walkers Corner was approved for use in 2000. Hixson Utility District alternates the use of the two production wells at Walkers Corner except when drought conditions occur when they are used simultaneously. The second production well increased the capacity of the well field by an additional 2 Mgal/d. The aquifer framework in the study area consists of dense Paleozoic carbonate rocks with secondary permeability that are mantled by thick residual clay-rich regolith in most of the area and by coarse-grained alluvium in the valley of North Chickamauga Creek. Cave Springs, one of the largest springs in Tennessee, derives its flow from conduits in a carbonate rock (karst) aquifer. Production wells at Cave Springs draw water from these conduits. Production wells at Walkers Corner primarily draw water from gravel zones in the regolith near the top of rock. Transmissivities estimated from hydraulic tests conducted across the Cave Springs area span a range from 240 to 900,000 feet squared per day (ft 2 /d) with a median value of 5,200 ft 2 /d. Recharge to the aquifer occurs from direct infiltration of precipitation and from losing streams. Most recharge occurs during the winter and spring months. Computer modeling was used to provide a better understanding of the ground-water-flow system and to simulate the effects of additional ground-water withdrawals. A numerical ground-water-flow model of the ground-water system was constructed and calibrated using MODFLOW 2000. Modeling results indicate that losing streams along the base of the Cumberland Plateau escarpment at the western edge of the study area are an important source of recharge to the ground-water system, supplying about 50 percent of the recharge to the study area. Direct infiltration of precipitation accounts for the remaining recharge to the study area. In 1999, ground-water withdrawals of 6.4 Mgal/d [9.9 cubic feet per second (ft 3 /s)] equaled about 11 percent of the total simulated ground-water recharge. The remaining ground-water recharge discharges to rivers (48 percent, 41.1 ft 3 /s), springs (19 percent, 16.8 ft 3 /s), and Chickamauga Lake (22 percent, 19.0 ft 3 /s). Drawdown at the Walkers Corner well field in 2000 was about 33 feet at the center of a cone of depression that is elongated along strike. If additional pumping at Walkers Corner increases withdrawals by 2 Mgal/d, simulated drawdown at the Walkers Corner well field increases to about 60 feet and simulated ground-water discharges decrease by amounts of 1.0 ft 3 /s to Chickamauga Lake, 0.8 ft 3 /s to North Chickamauga Creek, 0.5 ft 3 /s to Lick Branch-Rogers Spring drainage, 0.5 ft 3 /s to Poe Branch, and 0.2 ft 3 /s to Cave Springs.

Tennessee↗
USGS2002

Duration and Frequency Analysis of Lowland Flooding in Western Murfreesboro, Rutherford County, Tennessee, 1998-2000

Periodic flooding occurs at lowlands and sinkholes in and adjacent to the flood plain of the West Fork Stones River in the western part of Murfreesboro, Tennessee. Flooding in this area commonly occurs during the winter months from December through March. The maximum water level that flood waters will reach in a lowland or sinkhole is controlled by the elevation of the land surrounding the site or the overflow outlet. Maximum water levels, independent of overflow from the river, were estimated to be reached in lowlands and sinkholes in the study area every 1 to 4 years. Minor overflow from the West Fork Stones River (less than 1 foot in depth) into the study area has been estimated to occur every 10 to 20 years. Moderate overflow from the river (1 to 2 feet in depth) occurs on average every 20 to 50 years, while major river overflow (in excess of 2 feet in depth) can be expected every 50 years. Rainfall information for the area, and streamflow and water-level measurements from the West Fork Stones River, lowlands, sinkholes, caves, and wells in the study area were used to develop a flood-prone area map, independent of overflow from the river, for the study area. Water-level duration and frequency relations, independent of overflow from the river, were estimated for several lowlands, sinkholes, and wells in the study area. These relations are used to characterize flooding in lowland areas of western Murfreesboro, Rutherford County, Tennessee.

Tennessee↗