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At least 109 records · Page 6Linked to original sources
USGS2004

Hydrogeology and ground-water flow at Levee 31N, Miami-Dade County, Florida, July 2003 to May 2004: As part of the Comprehensive Everglades Restoration Plan

Introduction The Levee 31N Seepage Management Pilot Project began in 2001, as part of the Comprehensive Everglades Restoration Plan (CERP). The pilot project seeks to determine the appropriate technology needed to control seepage from Everglades National Park (ENP), and provide the appropriate amount of ground-water flow to minimize potential impacts to the West Well Field and Biscayne Bay. To meet these needs, a levee cut-off wall (vertical subsurface barrier) has been proposed along Levee 31N in Miami-Dade County to reduce seepage flow from ENP. During the wet season, ground water would be captured by wells adjacent to Levee 31N and diverted into a buffer area adjacent to ENP where sheetflow would be reestablished. An integrated, multidisciplinary investigation of ground-water flow is currently in progress by the South Florida Water Management District (SFWMD) and U.S. Army Corps of Engineers as part of the Levee 31N Seepage Management Pilot Project. Pre-seepage pilot wall ground-water flow patterns are being assessed through use of in situ heat-pulse flowmeter measurements, monitoring the vertical changes in hydraulic head and temperature, ground-water age dating, and measurement of the vertical change in ambient ground-water quality. A high-resolution hydrogeologic framework is needed as part of this effort. In 2003, the U.S. Geological Survey (USGS) initiated a study to characterize the surficial aquifer system in detail to a depth of about 100 feet below ground level in the Levee 31N study area, and to delineate karst preferential ground-water flow zones. This study was part of a cooperative agreement between the USGS and the SFWMD (USGS Joint Funding Agreement No. 04E0FL208011 and SFWMD Agreement No. CPO40324), and funded through CERP.

Florida↗
USGS2014

USGS Field Activities 11CEV01 and 11CEV02 on the West Florida Shelf, Gulf of Mexico, in January and February 2011

During January and February 2011 the U.S. Geological Survey (USGS), in cooperation with the University of South Florida (USF), conducted geochemical surveys on the west Florida Shelf. Data collected will allow USGS and USF scientists to investigate the effects of climate change on ocean acidification within the northern Gulf of Mexico, specifically, the effect of ocean acidification on marine organisms and habitats. This work is part of a larger USGS study on Climate and Environmental Variability (CEV). The first cruise was conducted from January 3 – 7 (11CEV01) and the second from February 17 - 27 (11CEV02). To view each cruise's survey lines, please see the Trackline page. Both cruises took place aboard the R/V Weatherbird II , a ship of opportunity led by Dr. Kendra Daly (USF), which departed and returned from Saint Petersburg, Florida. Data collection included sampling of the surface and water column (referred to as station samples) with lab analysis of pH, dissolved inorganic carbon (DIC), and total alkalinity. Augmenting the lab analysis was a continuous flow-through system with a Conductivity-Temperature-Depth (CTD) sensor, which also recorded salinity, and pH. Corroborating the USGS data are the vertical CTD profiles collected by USF. The CTD casts measured continuous vertical profiles of oxygen, chlorophyll fluorescence, optical backscatter, and transmissometer. Discrete samples for nutrients, chlorophyll, and particulate organic carbon/nitrogen were also collected during the CTD casts.

Florida↗
USGS1996

Statistical summaries of ground-water level data collected in the Suwannee River Water Management District, 1948 to 1994

Since 1948, ground-water level data have beensystematically collected from selected wells in theSuwannee River Water Management District (SRWMD) by the U.S. Geological Survey (USGS),the SRWMD, and other agencies. Records of waterlevels in the SRWMD (fig. 1), collected by the USGS and SRWMD through 1990, and by the SRWMD from 1990 to 1994, have been published for many years in the USGS annual report series "Water Resources Data for Florida." However, no systematic statistical summaries of water levels in the SRWMD have been previously published. The need for such statistical summary data forevaluations of drought severity, ground-water supplyavailability, and minimum water levels for regulatory purposes increases daily as demands for ground-water usage increase. Also, much of the base flow of the Suwannee River is dependent upon ground water. As the population and demand for ground water for drinking water and irrigation purposes increase, the ability to quickly and easily predict trends in ground-water availability will become paramount. In response to this need, the USGS, in cooperation with the SRWMD, compiled this report. Ground-water sta tistics for 136 sites are presented as well as figures showing water levels that were measured in wells from 1948 through September 1994. In 1994, the SRWMD and the USGS began a long- term program of cooperative studies designed tobetter understand minimum and maximum streamflows and ground-water levels in the SRWMD. Minimum and maximum flows and levels are needed by the district to manage the surface- and ground-water resources of the SRWMD and to maintain or improve the various ecosystems. Data evaluation was a necessary first step in the long- term SRWMD ground-water investigations program, because basic statistics for ground-water levels are not included in the USGS annual data reports such as "Water Resources Data for Florida, Water Year 1994" (Fran klin and others, 1995). Statistics included in this report were generated using the USGS computer pro gram ADAPS (Automatic Data Processing System) to characterize normal ground-water levels and depar tures from normal. The report has been organized so that the statisti cal analyses of water levels in the wells are presentedfollowing this introductory material, a description ofthe hydrogeology in the study area, and a description of the statistics used to present the water-level data. Specifically, the report presents statistical analyses for each well, as appropriate, in the following manner: Description of the well.Hydrographs of ground-water levels for the period of record, for the last 10 years of record, and for the last 5 years of record. Graphs of maximum, minimum, and mean of monthly mean ground-water levels for wells with 5 or more years of record.Frequency hydrographs (25, 50, and 75 percent) of monthly mean ground-water levels for wells with 5 or more years of record. Water-level data and statistical plots are grouped by county and sorted within the county by ascendingsite identification number. Well locations are plottedon county maps preceding the well descriptions andhydrographs.

Open-File Report↗
USGS2014

Methods for estimating the magnitude and frequency of floods for urban and small, rural streams in Georgia, South Carolina, and North Carolina, 2011

Reliable estimates of the magnitude and frequency of floods are essential for the design of transportation and water-conveyance structures, flood-insurance studies, and flood-plain management. Such estimates are particularly important in densely populated urban areas. In order to increase the number of streamflow-gaging stations (streamgages) available for analysis, expand the geographical coverage that would allow for application of regional regression equations across State boundaries, and build on a previous flood-frequency investigation of rural U.S Geological Survey streamgages in the Southeast United States, a multistate approach was used to update methods for determining the magnitude and frequency of floods in urban and small, rural streams that are not substantially affected by regulation or tidal fluctuations in Georgia, South Carolina, and North Carolina. The at-site flood-frequency analysis of annual peak-flow data for urban and small, rural streams (through September 30, 2011) included 116 urban streamgages and 32 small, rural streamgages, defined in this report as basins draining less than 1 square mile. The regional regression analysis included annual peak-flow data from an additional 338 rural streamgages previously included in U.S. Geological Survey flood-frequency reports and 2 additional rural streamgages in North Carolina that were not included in the previous Southeast rural flood-frequency investigation for a total of 488 streamgages included in the urban and small, rural regression analysis. The at-site flood-frequency analyses for the urban and small, rural streamgages included the expected moments algorithm, which is a modification of the Bulletin 17B log-Pearson type III method for fitting the statistical distribution to the logarithms of the annual peak flows. Where applicable, the flood-frequency analysis also included low-outlier and historic information. Additionally, the application of a generalized Grubbs-Becks test allowed for the detection of multiple potentially influential low outliers. Streamgage basin characteristics were determined using geographical information system techniques. Initial ordinary least squares regression simulations reduced the number of basin characteristics on the basis of such factors as statistical significance, coefficient of determination, Mallow’s Cp statistic, and ease of measurement of the explanatory variable. Application of generalized least squares regression techniques produced final predictive (regression) equations for estimating the 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probability flows for urban and small, rural ungaged basins for three hydrologic regions (HR1, Piedmont–Ridge and Valley; HR3, Sand Hills; and HR4, Coastal Plain), which previously had been defined from exploratory regression analysis in the Southeast rural flood-frequency investigation. Because of the limited availability of urban streamgages in the Coastal Plain of Georgia, South Carolina, and North Carolina, additional urban streamgages in Florida and New Jersey were used in the regression analysis for this region. Including the urban streamgages in New Jersey allowed for the expansion of the applicability of the predictive equations in the Coastal Plain from 3.5 to 53.5 square miles. Average standard error of prediction for the predictive equations, which is a measure of the average accuracy of the regression equations when predicting flood estimates for ungaged sites, range from 25.0 percent for the 10-percent annual exceedance probability regression equation for the Piedmont–Ridge and Valley region to 73.3 percent for the 0.2-percent annual exceedance probability regression equation for the Sand Hills region.

Georgia, North Carolina, South Carolina↗
USGS2001

U.S. Geological Survey Karst Interest Group: proceedings, St Petersburg, Florida February 13-16, 2001

Karst and similar landscapes are found in a wide range of biogeographic classes. In the U.S. for example, Everglades, Mammoth Cave, and Hawaii Volcanoes National Parks have little in common - except karst or pseudokarst, and a cultural past (even though these are very different). This diversity of geologic settings makes karst difficult to categorize and work with when designing a national program such as the recent NPS-USGS Geo-Indicators effort. A GIS-based approach with multiple datalayers is the only sane way to understand and convey the many relationships, in X, Y, and Z axes, between component ecosystems and cultural resources within karst and pseudokarst landscapes. Obviously, karst and cultural landscapes cross modern political as well as biogeographic boundaries. Here again, three-dimensional data are the foundation for understanding similar to that in anatomy and physiology: structure and function. In understanding where the most vulnerable 'pressure points' exist within karst landscapes, we can target landscape-scale ecosystem management to greatest effect. USGS and the National Cave and Karst research Institute could play an extremely significant role in cave and karst management on a national scale beyond NPS or other agency boundaries via cooperative management of three-dimensional karst datasets analogous to programs in several states.

Florida↗
USGS1997

Progress report on sediment analyses at selected faunal monitoring sites in north-central and northeastern Florida Bay

Florida Bay is a shallow, subtropical lagoon at the southern tip of the Florida peninsula. The 2200 square kilometer, triangular-shaped area is the site of modern carbonate sediment formation and deposition. The intricate ecosystem of the bay has undergone significant changes as the result of natural influences and human intervention. The purpose of this study is to investigate carbonate sediment characteristics and distribution in conjunction with faunal and floral to determine the substrate preferences of associated fauna and flora. The modern data provide the proxy data for down-core analyses of sediments, fauna and flora in order to document ecosystem changes in the bay. Selected sediment samples collected during 1996 from 18 sites in the northeastern and central bay were analyzed for insoluble residues, organic content, total carbonate, and percent of silt and clay sized particles. Insoluble residues range from 0.8% of the sediment in a shell lag to 11.5% with an average of 5.1%. Organic content ranged from a minimum of 1.43% of the sediment to 18.05% with an average of 7.6%. The total carbonate content ranged from 72.56% to 97.81%, averaging 87.98%. The percent silt and clay sized particles ranged from 13.75% to 63.62% for the samples analyzed. The insoluble residue content shows a general trend of decreasing insoluble residues from the northeastern bay toward the southwest. Organic content is variable throughout the bay and does not show a regional trend. Several sites show a trend of higher organic content in the samples collected in February as compared to those collected in July. Lithologic examination indicated that, in addition to the carbonate mud (less than 63mm), sample components included whole and fragmented mollusks, foraminifers, bryozoans, ostracods, and organic matter. The insoluble residues consisted of quartz sand and silt, clays and siliceous fossils. A component of the insoluble residues may be dust derived from Africa and transported to southern Florida by the prevailing winds. This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards or with the North American Stratigraphic Code. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Open-File Report↗
USGS1980

Evaluation of remote hydrologic data-acquisition systems, west-central Florida

The study provides an evaluation of the hydrologic applications of a land-line and two satellite data-relay systems operated during 1977-78 in the Southwest Florida Water Management District. These systems were tested to evaluate operational and reliability characteristics. Telephone lines were used to relay data in the land-line system, and the Geostationary Operational Environmental Satellite (GOES) and Land satellite (Landsat) were used in the satellite system. The land-line system was tested for 15 months at a streamflow site. Accurate data were obtained 94% of the time during the test period. Data losses were attributed to telephone-line interference, low-battery voltage, and vandalism. The GOES system was tested at a rainfall site for 17 months. During this period, 79% of the transmissions received from the station were relayed by the GOES system to the U.S. Geological Survey computer, resulting in successful processing of 88% of all possible rainfall observations. On the average, seven data transmissions were completed each day. The Landsat system was tested at a rainfall site for about 17 months and for about 8 months at a streamflow site. During these periods of operation, only about 2% of all data observations for the stations were successfully relayed by the Landsat system to the U.S. Geological Survey computer. An average of about three data transmissions was completed each day for each site. (USGS).

Florida↗
USGS2026

Methods for estimating selected low-flow frequency and mean annual flow statistics at gaged and ungaged locations on streams in Georgia, North Carolina, and South Carolina

The U.S. Geological Survey, in cooperation with the Georgia Department of Natural Resources (Environmental Protection Division), North Carolina Department of Environmental Quality (Division of Water Resources), North Carolina Department of Public Safety (Office of Recovery and Resiliency), and South Carolina Department of Environmental Services, updated low-flow frequency, mean annual flow, and flow-duration statistics at 843 streamgages in and near Georgia, North Carolina, and South Carolina. The low-flow frequency statistics are annual minimum 1-day average flow with a 10-year recurrence interval (1Q10), annual minimum 7-day average flow for 2- and 10-year recurrence intervals (7Q2 and 7Q10, respectively), and annual minimum 30-day average flow with 2- and 3-year recurrence intervals (30Q2 and 30Q3, respectively). Monthly 1Q10 and 7Q10, and W7Q10 flow statistics for the winter period (November–March) also are presented. By using data from 604 of the streamgages on streams with streamflows that are not substantially affected by regulation or diversion and are not tidally influenced, regional regression equations were developed to predict flow statistics with prediction intervals at ungaged locations on streams with those same criteria. The regional regression analysis included data from 132 streamgages from adjacent States Alabama, Florida, Tennessee, and Virginia. The final regional regression equations include variables such as drainage area, streamflow variability, precipitation, percentage of impervious area, and percentage of the basin in various ecoregions. The low-flow statistics for the streamgages analyzed and the regional regression equations will be integrated into the U.S. Geological Survey StreamStats application ( https://www.usgs.gov/streamstats ) for Georgia, North Carolina, and South Carolina. StreamStats generates basin characteristics needed to compute low-flow frequency statistics for ungaged locations. A trend analysis of annual minimum 7-day average flows was done for 78 streamgages with at least 30 years of continuous record. Trends were evaluated for 30-, 50‑, 70-, and 90-year periods, ending in climate year 2021, and independence and short- and long-term persistence assumptions were considered. For all trend analysis assumptions, most streamgages did not exhibit significant trends in annual minimum 7-day average flows. Trends in annual precipitation and air temperature were similarly evaluated for the period 1895–2021 to assess the variability of climate for Georgia, North Carolina, and South Carolina.

Georgia, North Carolina, South Carolina↗
USGS2014

Integration of seismic-reflection and well data to assess the potential impact of stratigraphic and structural features on sustainable water supply from the Floridan aquifer system, Broward County, Florida

The U.S. Geological Survey and Broward County water managers commenced a 3.5-year cooperative study in July 2012 to refine the geologic and hydrogeologic framework of the Floridan aquifer system (FAS) in Broward County. A lack of advanced stratigraphic knowledge of the physical system and structural geologic anomalies (faults and fractures originating from tectonics and karst-collapse structures) within the FAS pose a risk to the sustainable management of the resource. The principal objective of the study is to better define the regional stratigraphic and structural setting of the FAS in Broward County. The objective will be achieved through the acquisition, processing, and interpretation of new seismic-reflection data along several canals in Broward County. The interpretation includes integration of the new seismic-reflection data with existing seismic-reflection profiles along Hillsboro Canal in Broward County and within northeast Miami-Dade County, as well as with data from nearby FAS wellbores. The scope of the study includes mapping the geologic, hydrogeologic, and seismic-reflection framework of the FAS, and identifying stratigraphic and structural characteristics that could either facilitate or preclude the sustainable use of the FAS as an alternate water supply or a treated effluent repository. In addition, the investigation offers an opportunity to: (1) improve existing groundwater flow models, (2) enhance the understanding of the sensitivity of the groundwater system to well-field development and upconing of saline fluids, and (3) support site selection for future FAS projects, such as Class I wells that would inject treated effluent into the deep Boulder Zone.

Florida↗
USGS2001

Environmental quality and preservation; reefs, corals, and carbonate sands; guides to reef-ecosystem health and environment

Introduction In recent years, the health of the entire coral reef ecosystem that lines the outer shelf off the Florida Keys has declined markedly. In particular, loss of those coral species that are the building blocks of solid reef framework has significant negative implications for economic vitality of the region. What are the reasons for this decline? Is it due to natural change, or are human activities (recreational diving, ship groundings, farmland runoff, nutrient influx, air-borne contaminants, groundwater pollutants) a contributing factor and if so, to what extent? At risk of loss are biologic resources of the reefs, including habitats for endangered species in shoreline mangroves, productive marine and wetland nurseries, and economic fisheries. A healthy reef ecosystem builds a protective offshore barrier to catastrophic wave action and storm surges generated by tropical storms and hurricanes. In turn, a healthy reef protects the homes, marinas, and infrastructure on the Florida Keys that have been designed to capture a lucrative tourism industry. A healthy reef ecosystem also protects inland agricultural and livestock areas of South Florida whose produce and meat feed much of the United States and other parts of the world. In cooperation with the National Oceanic and Atmospheric Administration's (NOAA) National Marine Sanctuary Program, the U.S. Geological Survey (USGS) continues longterm investigations of factors that may affect Florida's reefs. One of the first steps in distinguishing between natural change and the effects of human activities, however, is to determine how coral reefs have responded to past environmental change, before the advent of man. By so doing, accurate scientific information becomes available for Marine Sanctuary management to understand natural change and thus to assess and regulate potential human impact better. The USGS studies described here evaluate the distribution (location) and historic vitality (thickness) of Holocene reefs in South Florida, relative to type of underlying bedrock morphology, and their varied natural response to rising sea level. These studies also assess movement and accumulation of sands, relative to direction of prevailing energy, and origin of the component sand grains. Geophysical data collected with highresolution sound-wave instruments that provide pictures of the sediment and bedrock are used to interpret sediment thickness. Reef thickness is determined by collecting limestone rock cores by drilling. Drill cores through reefs are used to identify the coral species that built them and to determine how reefs reacted to rising sea level. These data are supplemented by using isotope-dating techniques to derive the carbon-14 (C14) age of the corals and mangrove peat in the cores. Mangrove peat forms in very shallow water and at the shoreline but is found today buried beneath offshore reefs.

Open-File Report↗
USGS2019

Assessment of bird exposure to lead at Tyndall and Beale Air Force Bases, 2016–17

Soil contamination by lead (Pb) from past small munitions training on Beale Air Force Base, California, and Tyndall Air Force Base, Florida, may result in adverse effects for passerine birds that utilize the locations. A study was conducted during 2016-17 by the U.S. Geological Survey, in cooperation with the U.S. Fish and Wildlife Service and U.S. Air Force, at both Air Force Bases (AFBs) to assess the risk of bird exposure to Pb. Two different methods were used to estimate exposure. The first was analysis of blood and feather samples collected from birds captured on both AFBs, and the second was food chain modeling using data on Pb concentrations in dietary items (invertebrates and seeds) collected from both AFBs. Lead concentrations in blood and feathers for birds captured at Beale AFB indicate low exposure and risk; potential toxicity is possible based on blood and feather data for birds from Tyndall AFB. Food chain modeling utilizing dietary contamination indicates a risk likelihood of up to 35 percent at Beale AFB and up to 34 percent at Tyndall AFB. Lead exposure from incidental soil ingestion increased risk likelihood at both AFBs and is a significant uncertainty in this risk assessment. A companion data release for data collected during this project can be found at https://doi.org/10.5066/P92YXMQ2 .

California, Florida↗
USGS2024

Societal benefits of cyanobacteria harmful algal bloom management in Lake Okeechobee in Florida—Potential damages avoided during the 2018 event under U.S. Army Corps of Engineers Harmful Algal Bloom Interception, Treatment, and Transformation System scenarios

Freshwater harmful algal blooms (HABs) formed by blue-green algae, or cyanobacteria, have emerged as a global environmental problem. Their negative impacts on aquatic ecosystems can affect the benefits nature provides to human society by reducing water quality; inhibiting aquatic recreation; killing fish, wildlife, and pets; and posing a risk to human health. To manage harmful algal blooms, the Engineer Research and Development Center of the U.S. Army Corps of Engineers is developing an advanced technology called the Harmful Algal Bloom Interception, Treatment, and Transformation System (HABITATS), which has been tested in pilot demonstrations upstream of spillways at HAB-affected waterbodies in Florida. The U.S. Geological Survey and cooperators from the U.S. Department of the Interior Office of Policy Analysis investigated the societal benefits of HABITATS technology by using data from an actual 2018 harmful algal bloom in Lake Okeechobee to characterize the observed societal impacts and then comparing observed effects to hypothetical scenarios of HABITATS deployment. This study estimated an economic value of $5.5 million in foregone recreation as a result of closed boating ramp facilities and other restrictions on aquatic recreation such as fishing and swimming during the 2018 cyanobacteria harmful algal bloom outbreak. The change in housing sales prices that could have resulted from murky water or bad odor during that outbreak was estimated as $2.3 million. The team also investigated drinking water contamination and human illness but did not find significant societal impacts in this case. If HABITATS had been deployed, the avoided losses less the cost of management could have provided net societal benefits that ranged between negative $2.1 million and positive $0.8 million, depending on the vertical distribution of algae in the water column and the HABITATS version used. The study’s estimated societal benefit is undoubtedly a lower bound estimate because current scientific knowledge is inadequate to characterize, or monetize, all the impacts.

Florida↗
USGS1993

Application of ground-penetrating radar methods in determining hydrogeologic conditions in a karst area, west-central Florida

Ground-penetrating radar (GPR) is useful as a surface geophysical method for exploring geology and subsurface features in karst settings. Interpretation of GPR data was used to infer lithology and hydrogeologic conditions in west-central Florida. This study demonstrates how GPR methods can be used to investigate the hydrogeology of an area. GPR transmits radio- frequency electromagnetic waves into the ground and receives reflected energy waves from subsurface interfaces. Subsurface profiles showing sediment thickness, depth to water table and clay beds, karst development, buried objects, and lake-bottom structure were produced from GPR traverses obtained during December 1987 and March 1990 in Pinellas, Hillsborough, and Hardee Counties in west-central Florida. Performance of the GPR method is site specific, and data collected are principally affected by the sediment and pore fluids, conductances and dielectric constants. Effective exploration depths of the GPR surveys through predominately unsaturated and saturated sand and clay sediments at five study sites ranged from a few feet to greater than 50 feet below land surface. Exploration depths were limited when high conductivity clay was encountered, whereas greater exploration depths were possible in material composed of sand. Application of GPR is useful in profiling subsurface conditions, but proper interpretation depends upon the user's knowledge of the equipment and the local hydrogeological setting, as well as the ability to interpret the graphic profile.

Water-Resources Investigations Report↗
USGS2004

Effectiveness of a pressurized stormwater filtration system in Green Bay, Wisconsin: A study for the environmental technology verification program of the U.S. Environmental Protection Agency

A pressurized stormwater filtration system was installed in 1998 as a stormwater-treatment practice to treat runoff from a hospital rooftop and parking lot in Green Bay, Wisconsin. This type of filtration system has been installed in Florida citrus groves and sewage treatment plants around the United States; however, this installation is the first of its kind to be used to treat urban runoff and the first to be tested in Wisconsin. The U.S. Geological Survey (USGS) monitored the system between November 2000 and September 2002 to evaluate it as part of the U.S. Environmental Protection Agency's Environmental Technology Verification Program. Fifteen runoff events were monitored for flow and water quality at the inlet and outlet of the system, and comparison of the event mean concentrations and constituent loads was used to evaluate its effectiveness. Loads were decreased in all particulate-associated constituents monitored, including suspended solids (83 percent), suspended sediment (81 percent), total Kjeldahl nitrogen (26 percent), total phosphorus (54 percent), and total recoverable zinc (62 percent). Total dissolved solids, dissolved phosphorus, and nitrate plus nitrite loads remained similar or increased through the system. The increase in some constituents was most likely due to a ground-water contribution between runoff events. Sand/silt split analysis resulted in the median silt content of 78 percent at the inlet, 87 percent at the outlet, and 3 percent at the flow splitter.

Wisconsin↗
USGS1979

Evaluation of methods for estimating ground-water withdrawals in western Kansas

During 1978, methods of estimating ground-water withdrawals in western Kansas were examined and evaluated, using both existing data from the files of the U.S. Geological Survey and newly collected data. Values for annual ground-water withdrawals reported to the Division of Water Resources, Kansas State Board of Agriculture, by water users probably contain substantial errors because most individual users do not possess the means to measure or accurately estimate the discharge rates of their wells. Such reported values are estimated to average 10 to 15 percent higher than the actual discharge rate. Values obtained from discharge-totaling meters are reasonably accurate, but few wells are equipped with these meters, and the cost of equipping all wells with meters may be prohibitive. Measured rates of power consumption can give good estimates of total withdrawal from wells where the power consumption is measured. However, power-consumption values cannot be extrapolated reliably from one well to another. Three techniques are regarded as promising for estimating areal ground-water withdrawals from readily collected data: Examination of a small sample of withdrawal values from metered wells indicates that the statistical approach used by Luckey (1972) may be applied to western Kansas to estimate total withdrawal with acceptable accuracy in a large area from a statistical sample of measured values. Measured values of irrigation application at a small number of selected wells might be used to compute total withdrawal for irrigation by crop type and precipitation zone. Evaluation of reported values of irrigation-water application for selected crops in zones of generally similar precipitation showed that, although the reported values are judged to be erroneously high, the reported values were consistent with each other and with average precipitation. Power-consumption coefficients may be used to calculate an average coefficient for an area. The method described by Luckey (1972) was used to calculate the number of power-consumption coefficients that would have to be determined to estimate the mean power consumption of wells pumped by electric or natural-gas engines. The results indicate that as few as 100 values would produce results accurate to within 10 percent of the true average at the 95-percent confidence level. Thus, power coefficients for a particular type of irrigation system in any given area can be used even though values of power coefficients have little transfer value from well to well. Efforts by the Instrument Development Laboratofy of the U.S. Geological Survey to design improved instruments for measuring ground-water withdrawals have produced two promising results: An electronic running-time meter (Running-time Sentry) that was tested during 1978 in western Kansas and Florida appears to give accurate values of total pumping time. Large-scale testing of this prototype running-time meter is planned for 1979. A low-cost discharge-totaling meter (REELTOT), based on the concept of sensing the velocity head in a pipe with differential-pressure transducers permanently installed in the pipe, is nearly complete. Early prototypes of this instrument may be tested in western Kansas during 1979. For the remainder of this study, the three techniques for estimating areal ground-water withdrawals described above will be tested on a larger scale in Groundwater Management District No. 1, an area of about 1,800 square miles in west-central Kansas. About 150 randomly selected wells will be equipped with Running-time Sentry units and monitored for total withdrawal, instantaneous discharge, and power consumption. A few wells will be equipped with prototype discharge-totaling meters. The performance of the Sentry units and discharge-totaling meters will be evaluated. Areal estimates of withdrawal from measured withdrawal values, from average power-consumption coefficients, and from irrigation application by crop will be calculated and compared with each other and with reported values of withdrawal.

Kansas↗
USGS1999

Canal and wetland flow transport interaction; coupling models for canal and wetland interactions in the South Florida ecosystem

Introduction The U.S. Geological Survey is one of several agencies participating in the scientific effort to provide knowledge that can help protect and preserve the ecosystem of south Florida. One project of the intergovernmental South Florida Ecosystem Program (SFEP) is focused on developing a computer model to simulate the flow of water and analyze the transport of waterborne chemical constituents between canals and wetlands. Quantification of dynamic flows within the south Florida ecosystem is vital to understanding the implications of the residence time of water, potentially nutrient-enriched (with nitrates or phosphates) or contaminant-laden (with metals or pesticides), that can alter plant life and affect biological communities. Nutrients carried in the water conveyed by canals draining agricultural areas and dispersed into wetlands by canal discharges, by levee overflows, or by seepage are considered to be a major contributor to changes in the types of vegetation found in the Everglades. Freshwater inflows, typically of varying magnitudes and durations, not only influence the salinity of Florida Bay but also potentially carry toxic substances that can affect and alter the Bay's aquatic biota. The simulation capability being developed within the SFEP can be useful for identifying approaches to alleviate adverse impacts of excessive or deficient flows and transported constituents. Through strategic use of a simulation model, cause-and-effect relations between discharge sources, flow magnitudes, transport processes, and changes in vegetation and biota can be investigated. The effects of driving forces on nutrient cycling and contaminant transport can then be quantified, evaluated, and considered in the development of remedial management plans.

Florida↗
USGS1999

Hydrogeology and analysis of aquifer characteristics in west-central Pinellas County, Florida

The U.S. Geological Survey, in cooperation with Pinellas County, Florida, conducted an investigation to describe the hydrogeology and analyze the aquifer characteristics in west-central Pinellas County. A production test well and four monitor wells were constructed in Pinellas County at Walsingham Park during 1996-97. Water-quality sampling, static and dynamic borehole geophysical surveys, and hydraulic tests were conducted at the wells to delineate the hydrogeology at Walsingham Park. A 9-day aquifer test was conducted to determine the hydraulic characteristics of the aquifer system and observe the changes in water quality due to pumping. A numerical model was constructed to simulate the aquifer test and calculate values for hydraulic conductivity and storage coefficient for permeable zones and confining units at Walsingham Park. Final calibrated values for hydraulic conductivity for the different permeable zones and confining units at the test site were 18 feet per day for Upper Zone A, 750 feet per day for Lower Zone A, 1 foot per day for Zone B, 1x10-4 feet per day for the intermediate confining unit, and 10 feet per day for the semiconfining unit separating Upper Zone A and Lower Zone A. Final calibrated values for storage coefficient were 3.1x10-4 for Upper Zone A, 8.6x10-5 for Lower Zone A, 2.6x10-5 for Zone B, 3.1x10-4 for the intermediate confining unit, and 4.3x10-5 for the semiconfining unit separating Upper Zone A and Lower Zone A. Estimates of transmissivity for Upper Zone A and Lower Zone A were about 2,500 and 37,500 feet squared per day, respectively.

Florida↗
USGS2021

Groundwater chemistry, hydrogeologic properties, bioremediation potential, and three-dimensional numerical simulation of the sand and gravel aquifer at Naval Air Station Whiting Field, near Milton, Florida, 2015–20

The U.S. Geological Survey completed a study between 2015 and 2020 of groundwater contamination in the sand and gravel aquifer at a Superfund site in northwestern Florida. Groundwater-quality samples were collected from representative monitoring wells located along a groundwater-flow pathway and analyzed in the field and laboratory. In general, ambient groundwater in the sand and gravel aquifer is acidic, dilute, and oxic. Groundwater age-dating results indicate recharge to the contaminated parts of the aquifer occurred between the 1970s and 1980s. Natural gamma, electromagnetic induction, and borehole nuclear magnetic resonance logs indicated that aquifer hydraulic conductivities generally increased with depth as the aquifer formation material became coarser, characteristic of a prograding marginal-marine delta depositional environment. Aquifer formation material incubated with radiocarbon (carbon-14) cis -1,2-Dichloroethylene demonstrated biodegradation directly to carbon dioxide in contaminated and uncontaminated parts of the aquifer. A three-dimensional, numerical groundwater-flow MODFLOW model of the sand and gravel aquifer in the study area was constructed. The calibrated model reasonably reproduced measured groundwater heads and streamflows. Moreover, the model can be used to run simulations of outcomes of potential remedial strategies, such as monitored natural attenuation, as part of future feasibility studies in the area.

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