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At least 1,135 records · Page 63Linked to original sources

USGS2026

Monazite and xenotime U-Pb geochronology and thermometry of the Blue Ridge and Inner Piedmont of North Carolina: Implications for the thermal-metamorphic evolution of the southern Appalachian metamorphic “core”

The southern Appalachian orogen preserves a complex distribution of metamorphism and deformation varying in timing, magnitude, and spatial extent. These complexities give rise to disparate interpretations for southern Appalachian tectonic evolution, which complicates the testing and interpretation of tectonic models in this system. New monazite (Mnz) and xenotime (Xtm) laser ablation split stream (LASS) analyses alongside Mnz-Xtm thermometry in the orogenic core in the eastern Blue Ridge (EBR), western Inner Piedmont (WIP), and Cat Square terranes (CST) of North Carolina yield new constraints that define distinct pro- and retrograde metamorphic events. The EBR preserves two prograde thermal events: the Taconic (∼470-440 Ma, >660°C) and Neoacadian (∼380-340 Ma, 600–700°C), separated by a period of cooling (exhumation?) and followed by garnet breakdown from 339 to 329 Ma. Evidence of pervasive Neoacadian ductile deformation in the EBR is largely limited to the Brevard fault zone (BFZ), indicating that a major rheological gradient existed across the BFZ during the Neoacadian and early Alleghanian. Southeast of the BFZ, in the WIP and CST, monazite data define a protracted Neoacadian evolution from early mineral growth at ∼405 Ma at ∼450–600°C to >700°C at ∼360 Ma, followed by early Alleghanian retrograde metamorphism and deformation (<345 Ma, 350–500°C). These constraints, together with previously reported thermobarometric data, define a P-T-t evolution for the WIP and CST consistent with Neoacadian crustal flow, while the coeval presence of a thermal-rheological boundary along the BFZ further supports a model of Neoacadian crustal “escape” flow within the orogen.

North Carolina↗

USGS1979

Geologic and hydrologic aspects of tunneling in the Twin Cities area, Minnesota

This report presents the results of a pilot study of geologic and hydrologic aspects of tunneling in part of the Minneapolis-St. Paul (Twin Cities) metropolitan area, Minnesota. The Minnesota Geological Survey collected, compiled and interpreted geologic and engineering-test data and the U.S. Geological Survey complies and interpreted hydrologic data. The report was prepared on behalf of the U.S. Department of Transportation and funding was provided by that agency. A similar pilot study was recently made in the Los Angeles area, California (Yerkes and others, 1977).

Minnesota↗

USGS2014

Airborne electromagnetic data and processing within Leach Lake Basin, Fort Irwin, California

From December 2010 to January 2011, the U.S. Geological Survey conducted airborne electromagnetic and magnetic surveys of Leach Lake Basin within the National Training Center, Fort Irwin, California. These data were collected to characterize the subsurface and provide information needed to understand and manage groundwater resources within Fort Irwin. A resistivity stratigraphy was developed using ground-based time-domain electromagnetic soundings together with laboratory resistivity measurements on hand samples and borehole geophysical logs from nearby basins. This report releases data associated with the airborne surveys, as well as resistivity cross-sections and depth slices derived from inversion of the airborne electromagnetic data. The resulting resistivity models confirm and add to the geologic framework, constrain the hydrostratigraphy and the depth to basement, and reveal the distribution of faults and folds within the basin.

California↗

USGS1962

Surface water records of New Mexico, water year 1962

The surface-water records for the 1962 water year for gaging stations, partial- record stations, and miscellaneous sites within the State of New Mexico are given in this report. For convenience there are also included records for a few pertinent gaging stations in bordering States. The records were collected and computed by the Water Resources Division of the U. S. Geological Survey, under the direction of W. L. Heckler, district engineer, Surface Water Branch. This report is the second in a series presenting, annually, basic data on surface-water records by States. Through September 30, 1960, the records of discharge and stage of streams and contents and stage of lakes or reservoirs were published in an annual series of U. S. Geological Survey water-supply papers entitled "Surface Water Supply of the United States." Since 1951 there have been 20 volumes in the series; each volume covered an area whose boundaries coincided with those of certain natural drainage areas. The records in New Mexico were contained in Parts 7, 8, and 9 of that series. Beginning with the 1961 water year, streamflow records and related data will be released by the Geological Survey in annual reports on a State-boundary basis. Dis-tribution of these basic-data reports will be limited and primarily for local needs. The records later will be published in Geological Survey water-supply papers at 5-year intervals. These 5-year water-supply papers will show daily discharge and will be compiled on the same geographical areas previously used for the annual series; however, some of the 14 parts of conterminous United States will be further subdivided. The records for New Mexico will be published in water-supply papers covering Part 7 for stations in the Lower Mississippi River drainage, Part 8 for Western Gulf of Mexico drainage, and Part 9 for Colorado River drainage. For 1960 water year, the WSP Numbers for these parts were 1711, 1712, 1713 respectively. A compilation of records for these parts through 1950 water year is contained in WSP Nos. 1311, 1312, 1313 respectively; a 1951-60 compilation series will have WSP Nos. 1731, 1732, 1733.

New Mexico↗

USGS2026

Terrain-based map of mélange and intact rock at the junction of Coastal and Central Belt rocks of the Franciscan Complex between Gualala and Ukiah, northern California Coast Ranges

A terrain-based map of a large area of Franciscan Complex between the San Andreas and Maacama faults east of Point Arena, California, provides much new detail compared to prior mapping. The new map reveals an unusual, structurally disrupted area that is defined by northwest-trending patches of erosionally resistant topography interspersed in subdued topography. These two terrain types, here termed Hard and Soft, are distinguished using differences in the detailed shapes of individual topographic elements that in these rocks are indicative of relatively intact rock and severely sheared mélange. The disrupted area lies at the junction between rocks of two different parts of the Franciscan Complex: sandstone and argillite of the Coastal belt to the northwest and mélange and variously metamorphosed sandstone and other rocks of the Central belt to the southeast. The rocks in the disrupted area seem to consist largely of Coastal belt sandstone interspersed in Central belt mélange. They are separated from areally continuous Coastal belt to the west by the newly defined Cedars fault and from continuous mélange of the Central belt to the east by the newly defined Boonville fault. A plausible history to account for Coastal belt rocks and Central belt mélange now interspersed at the same structural level in the disrupted area is westward thrusting of Central belt over Coastal belt on the Coastal belt thrust, located mostly above the present level of exposure, followed by extensional dip-slip faulting involving both the disrupted area and its bounding faults. Most of the study area has been mapped on the ground only in reconnaissance. The terrain map was prepared largely by interpretation of small-scale aerial photographs, with distinctions in the steepness of slopes and curvature of ridge and side-hill crests made from the photographs. These distinctions were then confirmed by differences in their areal abundance determined through quantitative mapping of slope and curvature. Most of the remainder of the map was prepared in the same fashion directly from the slope and curvature maps. Geologic identities are assigned to as much of the area as possible, but some resistant parts, mostly in the disturbed area, remain identified solely as Hard terrain. Some units, mostly along the southern edge of the map, are compiled from published sources. This report serves as a description and explanation of the associated spatial database (Wentworth, 2025), which consists of attributed line and polygon shape files and metadata describing them.

California↗

USGS2008

Floods of May and June 2004 in central and eastern Ohio: FEMA disaster declaration 1519

Several severe thunderstorms that passed through Ohio between May 17 and June 17, 2004, produced large amounts of rain in an already wet central and eastern Ohio, resulting in flooding in this region from May 18 to June 21, 2004. Record peak streamflow occurred at three U.S. Geological Survey (USGS) streamgages. Damages caused by the flooding resulting from these storms were severe enough that 25 counties in central and eastern Ohio were declared Federal disaster areas. In all, there were two storm- or flood-related deaths, 3,529 private structures damaged or destroyed, and an estimated $43 million in damages. This report describes the meteorological factors that resulted in severe flooding in central and eastern Ohio between May 18 and June 21, 2004, and addresses the damages caused by the storms and flooding. Peak-stage, peak-streamflow, and recurrence-interval data are reported for selected USGS streamgages. Flood profiles determined by the USGS are presented for selected streams.

Ohio↗

USGS1978

Description of wells at Beale Air Force Base and vicinity, California

The study area occupies approximately 168 square miles of the Sacramento Valley. The study area boundary is the Yuba River in the north, the Feather River in the west, the Bear River in the south, and the Sierra Nevada foothills in the east. Between December 1976 and March 1977, 640 wells were selectively canvassed and 274 water levels were taken in the wells canvassed Thirty-six water levels measured in March and April 1976 are recorded in this report. Descriptive data for water wells and water levels are recorded in table 1, and location of wells is shown on maps 1-23.

California↗

USGS1980

Effects of herbicide usage on water quality of selected streams in Wyoming

During 1977 and 1978 the Wyoming Department of Agriculture, in conjunction with county weed and pest control districts, conducted a noxious-weed-control program in Wyoming. The herbicides primarily used were picloram, 2,4-D, and dicamba. The U.S. Geological Survey, in cooperation with the Wyoming Department of Agriculture, sampled and analyzed water from selected streams for these herbicides plus silvex; 2,4,5-T; and 2,4-DP. This report contains data for samples collected during 1977 and 1978. The most commonly detected herbicides in water samples were 2,4-D with 41-percent nonzero values and picloram with 34.5-percent nonzero values. Herbicide occurrence in bottom-material samples was uncommon; dicamba was found with 9-percent nonzero values. The maximum herbicide concentration in water was 1.1 micrograms per liter of 2,4-D, and the maximum herbicide concentration in bottom material was 8.0 micrograms per kilogram of 2,4-D. Based on available toxicity data and water-quality criteria, these herbicide concentrations do not constitute dangerous or harmful concentrations to humans or to the environment.

Wyoming↗

USGS2019

Triangle area water supply monitoring project, North Carolina-Summary of monitoring activities, quality assurance, and data, October 2015–September 2017

Surface-water supplies are important sources of drinking water for residents in the Triangle area of North Carolina, which is located within the upper Cape Fear and Neuse River Basins. Since 1988, the U.S. Geological Survey and a consortium of local governments have tracked water-quality conditions and trends in several of the area’s water-supply lakes and streams. This report summarizes data collected through this cooperative effort, known as the Triangle Area Water Supply Monitoring Project, during October 2015 through September 2016 (water year 2016) and October 2016 through September 2017 (water year 2017). Major findings for this period include the following: More than 5,000 individual measurements of water quality were made at a total of 20 sites—7 in the Neuse River Basin and 13 in the Cape Fear River Basin. Only the measurements from the photic zone and 1 meter below the water surface are documented in this report. Twenty-nine water-quality properties or constituents are presented in this report; State water-quality thresholds exist for 11 of these. All observations met State water-quality thresholds for hardness, chloride, fluoride, sulfate, and nitrate plus nitrite. North Carolina water-quality thresholds were exceeded one or more times for dissolved oxygen, dissolved-oxygen percent saturation, pH, water temperature, turbidity, and chlorophyll a .

North Carolina↗

USGS2021

Triangle Area Water Supply Monitoring Project, North Carolina—Summary of monitoring activities, quality assurance, and data, October 2017–September 2019

Surface-water supplies are important sources of drinking water for residents in the Triangle area of North Carolina, which is located within the upper Cape Fear and Neuse River Basins. Since 1988, the U.S. Geological Survey and a consortium of local governments have tracked water-quality conditions and trends in several of the area’s water-supply lakes and streams. This report summarizes data collected through this cooperative effort, known as the Triangle Area Water Supply Monitoring Project, from October 2017 through September 2018 (water year 2018) and from October 2018 through September 2019 (water year 2019). Major findings for this period include the following: More than 7,500 individual measurements of water quality were made at 20 sites—7 in the Neuse River Basin and 13 in the Cape Fear River Basin. For the lake sites, only measurements from the photic zone and 1 meter below the water surface are documented in this report. Thirty-six water-quality properties or constituents are presented in this report; the State of North Carolina water-quality thresholds are presented for 11 of these. All observations met the State of North Carolina water-quality thresholds for water temperature, hardness, chloride, fluoride, sulfate, and nitrate plus nitrite. The State of North Carolina water-quality thresholds were exceeded one or more times for dissolved oxygen, dissolved-oxygen percent saturation, pH, turbidity, and chlorophyll a .

North Carolina↗

USGS2007

Flood of July 27-31, 2006, on the Grand River near Painesville, Ohio

Two separate weather systems produced storms resulting in more than 11 inches of rain in parts of Lake County, Ohio, on July 27-28, 2006. As a result of the storms and ensuing flooding caused by the weather systems, the counties of Lake, Geauga, and Ashtabula were declared Federal and State disaster areas, with damages estimated at $30 million and one fatality in Lake County. About 600 people were evacuated in Lake County. The U.S. Geological Survey streamflow-gaging station at Grand River near Painesville, Ohio (station 04212100), had a record peak stage of 19.35 feet (elevation, 614.94 feet), with a record peak streamflow of 35,000 cubic feet per second, and an estimated recurrence interval of approximately 500 years. This report describes the meteorological factors that resulted in severe flooding on the Grand River near Painesville from July 27 to July 31, 2006, and addresses the damages caused by the storms and flooding. Peak-stage, peak-streamflow, and recurrence-interval data are reported for the Grand River near Painesville. A plot of high-water marks is also presented for the Grand River in a reach that includes the City of Painesville, Painesville Township, the Village of Fairport Harbor, and the Village of Grand River.

Open-File Report↗

USGS1970

Digital computer terrain mapping from multispectral data, and evaluation of proposed Earth Resources Technology Satellite (ERTS) data channels, Yellowstone National Park preliminary report

Digital computer processing of 12 wavelength bands of visible and reflective infrared scanner data has resulted in successful automatic computer mapping of eight terrain units in a Yellowstone National Park test site. Target areas in the scene were selected for training the computer. Statistical parameters of radiance such as mean, standard deviation, divergence, and covariance were computed for each category of material. These data were used in the computer program to determine which channels are most useful for recognition of all object categories studied, and to actually classify all the unknown data points into the known categories. The following terrain types have been mapped with greater than 80 percent accuracy in a 12-square-mile area with 1,800 feet of relief: bedrock exposures, talus, vegetated rock rubble, glacial kame terrace, glacial till, forest, bog, and water, and shadows. In addition, shadows of clouds and cliffs are depicted. In addition, studies were made of the effectiveness of the proposed Earth Resources Technology Satellite (ERTS) data channels as compared to the computer-selected best four channels in the automatic recognition and mapping of the same terrain types based on simulations, using the same set of data. These simulations resulted in maps whose accuracies were only a few percent less than that using the best set of four channels; they indicate that the ERTS data channels are likely to be successful for terrain analysis of a wide variety of categories encompassing a broad range of spectral reflectance. These studies also indicate that, for a broad range of terrain categories, many' combinations of 3 or 11 channels of data would be satisfactory. We need worry about careful selection of specific wavelength bands only if there is a specific category being sought.

Idaho, Montana, Wyoming↗

USGS1996

Effectiveness of highway-drainage systems in preventing contamination of ground water by road salt, Route 25, southeastern Massachusetts; description of study area, data collection programs, and methodology

Four test sites along a 7-mile section of Route 25 in southeastern Massachusetts, each representing a specific highway-drainage system, were instrumented to determine the effectiveness of the drainage systems in preventing contamination of ground water by road salt. One of the systems discharges highway runoff onsite through local drainpipes. The other systems use trunkline drainpipes through which runoff from highway surfaces, shoulders, and median strips is diverted and discharged into either a local stream or a coastal waterway. Route 25 was completed and opened to traffic in the summer of 1987. Road salt was first applied to the highway in the winter of 1987-88. The study area is on a thick outwash plain composed primarily of sand and gravel. Water-table depths range from 15 to 60 feet below land surface at the four test sites. Ground-water flow is in a general southerly direction, approximately perpendicular to the highway. Streamflow in the study area is controlled primarily by ground-water discharge. Background concentrations of dissolved chloride, sodium, and calcium-the primary constituents of road salt-are similar in ground water and surface water and range from 5 to 20, 5 to 10, and 1 to 5 milligrams per liter, respectively. Data-collection programs were developed for monitoring the application of road salt to the highway, the quantity of road-salt water entering the ground water, diverted through the highway-drainage systems, and entering a local stream. The Massachusetts Highway Department monitored road salt applied to the highway and reported these data to the U.S. Geological Survey. The U.S. Geological Survey designed and operated the ground-water, highway- drainage, and surface-water data-collection programs. A road-salt budget will be calculated for each test site so that the effectiveness of the different highway-drainage systems in preventing contamination of ground water by road salt can be determined.

Open-File Report↗

USGS2001

Analytical data for waters of the Harvard Open Pit, Jamestown Mine, Tuolumne County, California, March 1998-September 1999

The Jamestown mine is located in the Jamestown mining district in western Tuolumne County, California (see Fig. 1). This district is one of many located on or near the Melones fault zone, a major regional suture in the Sierra Nevada foothills. The districts along the Melones fault comprise the Mother Lode gold belt (Clark, 1970). The Harvard pit is the largest of several open pits mined at the Jamestown site by Sonora Mining Corporation between 1986 and 1994 (Fig. 2; Algood, 1990). It is at the site of an historical mine named the Harvard that produced about 100,000 troy ounces of gold, mainly between 1906 and 1916 (Julihn and Horton, 1940). Sonora Mining mined and processed about 17,000,000 short tons of ore, with an overall stripping ratio of about 4.5:1, yielding about 660,000 troy ounces of gold (Nelson and Leicht, 1994). Most of this material came from the Harvard pit, which attained dimensions of about 2700 ft (830 m) in length, 1500 ft (460 m) in width, and 600 ft (185 m) in depth. The bottom of the pit is at an elevation of 870 ft (265 m). Since mining operations ceased in mid-1994, the open pit has been filling with water. As of November, 2000, lake level had reached an elevation of about 1170 ft (357 m). Water quality monitoring data gathered after mine closure showed rising levels of arsenic, sulfate, and other components in the lake, with particularly notable increases accompanying a period of rapid filling in 1995 (County of Tuolumne, 1998). The largest potential source for arsenic in the vicinity of the Harvard pit is arsenian pyrite, the most abundant sulfide mineral related to gold mineralization. A previous study of weathering of arsenian pyrite in similarly mineralized rocks at the Clio mine, in the nearby Jacksonville mining district, showed that arsenic released by weathering of arsenian pyrite is effectively attenuated by adsorption on goethite or coprecipitation with jarosite, depending upon the buffering capacity of the pyrite-bearing rock (Savage and others, 2000). Although jarosite would be expected to dissolve in water having the composition of the developing pit lake, iron oxyhydroxide species (ferrihydrite and goethite) would be stable, and strong partitioning of arsenic onto suspended particles or bottom sediments containing these iron phases would be expected. Arsenic release to the lake would not be expected until stratification develops, producing a reducing, non-circulating hypolimnion in which the iron phases would be destroyed by dissolution. The fact that arsenic concentrations increased rapidly before the pit lake was deep enough to stratify shows that arsenic may not be attenuated in the ways that the earlier Clio mine area study indicated, and suggested that our understanding of release and transport of arsenic in this environment is incomplete. Therefore, in 1997 we decided to study the chemical evolution of the Harvard pit lake as part of a project on environmental impacts of gold mining in the Sierra Nevada, and in early 1998 we developed a cooperative study with several of the investigators in the Stanford University Department of Geological and Environmental Sciences who had done the Clio study. The U.S. Geological Survey portion of the project has been funded by the Mineral Resources Program. It is anticipated that a better understanding of the release and transport of arsenic into the Harvard pit lake and its accumulation there will contribute to more accurate predictions of arsenic release from weathering of sulfide-bearing rocks exposed by mining or other activities or events, and to better forecasts of pit lake evolution in this and similar environments, leading to more effective monitoring and mitigation strategies. An accurate predictive model is needed for the Harvard pit lake to forecast trends in metal concentrations, particularly arsenic, and also concentrations of major cations and anions. As the lake approaches pre-mining groundwater levels the lake water could move down the hydrologic gradient to the southeast into domestic wells, and could also affect the surface water of Woods Creek (see Figures 1-3). This report presents data for water samples collected from March, 1998 through September, 1999. Selected preliminary data for the pit lake for the 1998 calendar year have been reported (Savage and others, 2000).

California↗

USGS1952

Evaluation of streamflow records in Flathead River basin, Montana

This report presents data which are, in general, supplementary to those of the surface-water investigations made in the past by the Geological Survey. Those investigations have consisted essentially of the operation of the many gaging stations on the Flathead River and tributaries. The data presented were obtained from a detailed field investigation of the various manmade devices that are factors influencing the quantity or regimen of the flow at the gaging stations. These factors include diversions from the stream, bypass channels carrying water around the gaging stations, return flow from irrigation or other projects, storage and release of flood waters, and other similar factors. Where feasible, the location, size, effect upon the streamflow, periods of use, method of operation, and similar information are given. The information is segregated into sections corresponding to areas determined by the location of gaging stations. An index of streamflow records is included. A section dealing with the adequacy of .available water-resources data, including location and period of record, also is included. This information is given in general terms only, and is portrayed mainly by maps and graphs.

Montana↗

USGS2013

Water resources of Assumption Parish, Louisiana

Information concerning the availability, use, and quality of water in Assumption Parish, Louisiana, is critical for proper water-supply management. The purpose of this fact sheet is to present information that can be used by water managers, parish residents, and others for management of this vital resource. Information on the availability, past and current use, use trends, and water quality from groundwater and surface-water sources in the parish is presented. Previously published reports and data stored in the U.S. Geological Survey’s National Water Information System (http://waterdata.usgs.gov/nwis) are the primary sources of the information presented here. In 2010, about 21.4 million gallons per day (Mgal/d) of water were withdrawn in Assumption Parish, including about 12.4 Mgal/d from surface-water sources and 9.03 Mgal/d from groundwater sources. Withdrawals for industrial use accounted for about 16.4 Mgal/d or 76 percent of the total water withdrawn. Other categories of use included public supply, rural domestic, livestock, general irrigation, and aquaculture.Water-use data collected at 5-year intervals from 1960 to 2010 indicated that water withdrawals peaked in 2000 at about 29.7 Mgal/d.

Louisiana↗

USGS1998

Hydrogeology and simulation of ground-water flow in the Paluxy aquifer in the vicinity of Landfills 1 and 3, U.S. Air Force Plant 4, Fort Worth, Texas

Ground-water contamination of the surficial terrace alluvial aquifer has occurred at U.S. Air Force Plant 4, a government-owned, contractor-operated facility, northwest of Fort Worth, Texas. A poorly constructed monitoring well, P–22M, open to the underlying middle zone of the Paluxy aquifer was installed at landfill 3, October 1987, allowing leakage of contaminated ground water to reach the Paluxy aquifer. This well was plugged and abandoned in November 1995. Additionally, volatile organic compounds have been detected in fractures in the Goodland-Walnut confining unit, the hydrogeologic unit separating the terrace alluvial aquifer from the underlying Paluxy aquifer, beneath the western part of landfill 1. Volatile organic compounds in concentrations near the analytical detection limit were detected in the upper Paluxy prior to the drilling of well P–22M. The ground-water-flow simulation model described in this report was developed to examine the best logistically feasible location to install recovery wells to capture the low concentration (less than 100 micrograms per liter) trichloroethylene plume beneath landfills 1 and 3 (west Paluxy plume). Once the recovery wells were installed (1996), the simulation model was recalibrated with new data. This report documents the capture area of the installed recovery wells. Four geologic units are pertinent to this site-specific model. From oldest to youngest, these are the Glen Rose Formation, Paluxy Formation, Walnut Formation, and Goodland Limestone. The Glen Rose Formation is relatively impermeable in the study area and forms the confining unit underlying the Paluxy Formation. The Paluxy Formation forms the Paluxy aquifer, which is a public drinking water supply for the City of White Settlement. The Walnut Formation and Goodland Limestone form the Goodland-Walnut confining unit overlying the Paluxy aquifer. Near landfill 3, gamma-ray logs indicate three distinct zones of the Paluxy Formation; upper, middle, and lower. The formation is about 170-feet thick near landfill 3, and each zone is about 57-feet thick. Two steady-state simulations using the computer program MODFLOW were analyzed using the particle-tracking computer program, MODPATH. One simulation is the calibration simulation using Paluxy aquifer water-level data for May 1993. The second simulation includes the installed recovery wells. A variably spaced grid was designed for the model. The smallest grid cells, 25 by 25 feet, are in the vicinity of landfills 1 and 3. The largest cells, 4,864.5 by 1,441.5 feet, are at the northwestern corner of the model grid near the Parker-Tarrant County line. The modeling was accomplished with three layers representing the upper, middle, and lower zones of the Paluxy aquifer. Particles, which represent contaminant molecules moving in solution with the ground water, were tracked from well P–22M and an area below landfill 1, at the top of the upper zone of the Paluxy aquifer, for 9 years (forward tracking). The forward tracking estimates where contaminants might move by advection from 1987 to 1996. Analysis of backward tracking from the new recovery wells indicates that the simulated contributing area to the recovery wells intercepts the contaminant plume, minimizing off-site migration of the west Paluxy plume. To determine the effectiveness of the recovery wells, monitoring wells southeast of Building 14 have been installed (1996–97) for sampling.

Texas↗

USGS2018

Comparison of NEXRAD multisensor precipitation estimates to rain gage observations in and near DuPage County, Illinois, 2002–12

In this report, precipitation data from 2002 to 2012 from the hourly gridded Next-Generation Radar (NEXRAD)-based Multisensor Precipitation Estimate (MPE) precipitation product are compared to precipitation data from two rain gage networks—an automated tipping bucket network of 25 rain gages operated by the U.S. Geological Survey (USGS) and 51 rain gages from the volunteer-operated Community Collaborative Rain, Hail, and Snow (CoCoRaHS) network—in and near DuPage County, Illinois, at a daily time step to test for long-term differences in space, time, and distribution. The NEXRAD–MPE data that are used are from the fifty 2.5-mile grid cells overlying the rain gages from the other networks. Because of the challenges of measuring of frozen precipitation, the analysis period is separated between days with or without the chance of freezing conditions. The NEXRAD–MPE and tipping-bucket rain gage precipitation data are adjusted to account for undercatch by multiplying by a previously determined factor of 1.14. Under nonfreezing conditions, the three precipitation datasets are broadly similar in cumulative depth and distribution of daily values when the data are combined spatially across the networks. However, the NEXRAD–MPE data indicate a significant trend relative to both rain gage networks as a function of distance from the NEXRAD radar just south of the study area. During freezing conditions, of the USGS network rain gages only the heated gages were considered, and these gages indicate substantial mean undercatch of 50 and 61 percent compared to the NEXRAD–MPE and the CoCoRaHS gages, respectively. The heated USGS rain gages also indicate substantially lower quantile values during freezing conditions, except during the most extreme (highest) events. Because NEXRAD precipitation products are continually evolving, the report concludes with a discussion of recent changes in those products and their potential for improved precipitation estimation. An appendix provides an analysis of spatially combined NEXRAD–MPE precipitation data as a function of temperature at an hourly time scale and indicates, among other results, that most precipitation in the study area occurs at moderate temperatures of 30 to 74 degrees Fahrenheit. However, when precipitation does occur, its intensity increases with temperature to about 86 degrees Fahrenheit.

Illinois↗