Search USGS⌕ Search

SEARCH · Search USGS

Results for “Computers and Geology”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,747 records · Page 97Linked to original sources
USGS2023

Summary and conclusions

Executive Summary Chromium concentrations in rock and aquifer material in Hinkley and Water Valleys in the Mojave Desert, 80 miles northeast of Los Angeles, California, are generally low compared to the average chromium concentration of 185 milligrams per kilogram (mg/kg) in the average bulk continental crust. Chromium concentrations in felsic, coarse-textured “Mojave-type” deposits, composed of Mojave River stream (alluvium) and lake-margin (beach) deposits sourced from the Mojave River, are as low as 5 mg/kg, with a median concentration of 23 mg/kg in aquifer materials adjacent to the screened intervals of sampled wells. The most abundant chromium-containing mineral within aquifer materials in Hinkley and Water Valleys is magnetite. Magnetite is resistant to weathering, and about 90 percent of chromium remains within unweathered mineral grains. However, chromium-containing hornblende diorite and basalt are present in surrounding uplands, and chromium-containing actinolite is present within some aquifer materials. Although geologic abundance of chromium is clearly important, hexavalent chromium, Cr(VI), concentrations in alkaline oxic groundwater are related to additional factors. Hexavalent chromium concentrations in groundwater are influenced by a combination of processes including (1) mineralogy and the weathering rates of chromium-containing minerals; (2) texture of aquifer deposits; (3) accumulation of chromium weathered from minerals within surface coatings on mineral grains; (4) oxidation of accumulated Cr(III) to Cr(VI) in the presence of manganese oxides (Mn oxides), including the abundance and oxidation states of those Mn oxides; (5) pH-dependent desorption of chromium from coatings on the surfaces of mineral grains into groundwater during appropriate aqueous geochemical conditions; and (6) age (time since recharge) of groundwater. The pH of groundwater increases with groundwater age (time since recharge) as a result of silicate weathering, and desorption of Cr(VI) from aquifer deposits increases with increasing pH as long as groundwater remains oxic. In the absence of the detailed geologic, geochemical, and hydrologic data collected as part of this study, pH-dependent sorption, evaluated as the Cr(VI) occurrence probability at the measured pH, is an effective indicator of natural or anthropogenic Cr(VI). The Pacific Gas and Electric Company (PG&E) Hinkley compressor station is used to compress natural gas as it is transported through a pipeline from Texas to California. Between 1952 and 1964, cooling water containing Cr(VI) was discharged to unlined ponds and released into groundwater in unconsolidated aquifers. The extent of groundwater containing evidence of at least some anthropogenic Cr(VI) was 5.5 square miles (mi 2 ) and was estimated using a summative scale incorporating geologic, geochemical, and hydrologic data collected from more than 100 wells between March 2015 and November 2017. The summative-scale Cr(VI) plume extent is larger than the 2.2 mi 2 extent of the October–December 2015 (Q4 2015) regulatory Cr(VI) plume but is smaller than the 8.3 mi 2 maximum mapped extent of Cr(VI) greater than the interim regulatory Cr(VI) background concentration of 3.1 micrograms per liter (μg/L). The summative-scale Cr(VI) plume is within felsic, low-chromium aquifer material deposited by the Mojave River described as Mojave-type deposits and is within the area covered by the PG&E monitoring well network. Background Cr(VI) concentrations were calculated using the computer program ProUCL 5.1 as the upper 95-percent tolerance limit, UTL 95 , using data from wells outside the summative-scale Cr(VI) plume extent collected between April 2017 and March 2018. The overall UTL 95 for undifferentiated, unconsolidated deposits in the eastern and western subareas and the northern subarea upgradient of the Mount General fault in Hinkley Valley was 3.8 μg/L; this value is similar to the overall UTL 95 value of 3.9 μg/L calculated for Mojave-type deposits in Hinkley and Water Valleys, and is similar to the maximum Cr(VI) concentration of older groundwater in contact with Mojave-type deposits of 3.6 μg/L. In most cases the overall UTL 95 value may be an acceptable Cr(VI) background value near the Cr(VI) plume margin; however, UTL 95 values for the various subareas in Hinkley and Water Valleys provide greater resolution of Cr(VI) background that may be important for some purposes. The UTL 95 values for undifferentiated, unconsolidated deposits in the eastern, western, and northern subareas upgradient of the Mount General fault were 2.8, 3.8, and 4.8 μg/L, respectively. The UTL 95 value of 2.8 μg/L for wells screened in undifferentiated, unconsolidated deposits in the eastern subarea is important for plume management because the Hinkley compressor station and most of the summative-scale Cr(VI) plume are within the eastern subarea. A UTL 95 value of 2.3 μg/L was calculated for Mojave-type deposits downgradient from the Hinkley compressor station. This value represents Cr(VI) concentrations that may have been present in that part of the aquifer had Cr(VI) not been released from the Hinkley compressor station, and it reflects coarser textured deposits in this area and the proximity of those deposits to recharge areas along the Mojave River that results in younger (post-1952), less alkaline groundwater than in wells farther downgradient. This value may be a suitable metric for Cr(VI) cleanup goals within the Cr(VI) plume after regulatory updates. A separate UTL 95 value of 5.8 μg/L was calculated for mudflat/playa deposits and older groundwater near Mount General in the eastern subarea. The UTL 95 values calculated for undifferentiated, unconsolidated deposits in the northern subarea downgradient from the Mount General fault and in Water Valley, including lacustrine (lake) deposits and material eroded from basalt and Miocene deposits, were 9.0 and 6.4 μg/L, respectively. Hexavalent chromium concentrations in more than 70 domestic wells sampled between January 27 and 31, 2016, ranged from less than the study reporting level of 0.1–4.0 μg/L, with a median concentration of 1.2 μg/L. Hexavalent chromium concentrations in water from domestic wells did not exceed UTL 95 values within subareas where the wells were located. Water from 47 percent of domestic wells sampled between January 27 and 31, 2016, had arsenic, uranium, or nitrate concentrations above a maximum contaminant level. Anthropogenic Cr(VI) within groundwater downgradient from the Hinkley compressor station is treated by PG&E using bioremediation by adding ethanol as a reductant within a volume of aquifer known as the in situ reactive zone (IRZ). Laboratory microcosm studies showed that Cr(VI) is rapidly reduced to Cr(III) with additions of ethanol. Reduced Cr(III) is sorbed and is sequestered into crystalline iron and manganese oxides on the surfaces of mineral grains within the microcosms during a period of several months. Trivalent chromium was reoxidized back to Cr(VI) within 2 weeks of return to oxic (oxygen present) conditions within the microcosms. As much as 10 percent of added Cr was oxidized to Cr(VI) in microcosms prepared using recent Mojave River aquifer material, and as much as 20 percent of added Cr was oxidized to Cr(VI) in microcosms prepared using older Mojave River aquifer material. Less Cr(VI) (less than 3 percent of Cr added before reduction) was released to the aqueous phase, and this release occurred following longer time periods of oxygen exposure. Sequestration of chromium with manganese oxides during reduction facilitates reoxidation of Cr(III) to Cr(VI) under oxic conditions. Future maintenance of anoxic (oxygen absent) conditions would ensure continued sequestration of chromium as Cr(III) within IRZ treated portions of the Cr(VI) plume. Although Cr(VI) within the summative-scale Cr(VI) plume may have an anthropogenic history associated with releases from the Hinkley compressor station, Cr(VI) concentrations less than the UTL 95 values for the various subareas may not require regulatory attention. The regulatory Cr(VI) plume can be updated using the UTL 95 values calculated as part of this study. The updated regulatory Cr(VI) plume extent would lie within the summative-scale Cr(VI) plume extent. The authority to establish regulatory Cr(VI) background values, clean-up goals, and future site management practices resides with the Lahontan Regional Water Quality Control Board.

California↗
USGS2008

Bathymetric contour maps of lakes surveyed in Iowa in 2005

The U.S. Geological Survey, in cooperation with the Iowa Department of Natural Resources, conducted bathymetric surveys on seven lakes in Iowa during 2005 (Arrowhead Pond, Central Park Lake, Lake Keomah, Manteno Park Pond, Lake Miami, Springbrook Lake, and Yellow Smoke Lake). The surveys were conducted to provide the Iowa Department of Natural Resources with information for the development of total maximum daily load limits, particularly for estimating sediment load and deposition rates. The bathymetric surveys provide a baseline for future work on sediment loads and deposition rates for these lakes. All of the lakes surveyed in 2005 are man-made lakes with fixed spillways. Bathymetric data were collected using boat-mounted, differential global positioning system, echo depth-sounding equipment, and computer software. Data were processed with commercial hydrographic software and exported into a geographic information system for mapping and calculating area and volume. Lake volume estimates ranged from 47,784,000 cubic feet (1,100 acre-feet) at Lake Miami to 2,595,000 cubic feet (60 acre-feet) at Manteno Park Pond. Surface area estimates ranged from 5,454,000 square feet (125 acres) at Lake Miami to 558,000 square feet (13 acres) at Springbrook Lake.

Iowa↗
USGS2013

Flood-inundation maps for the White River at Spencer, Indiana

Digital flood-inundation maps for a 5.3-mile reach of the White River at Spencer, Indiana, were created by the U.S. Geological Survey (USGS) in cooperation with the Indiana Office of Community and Rural Affairs. The inundation maps, which can be accessed through the USGS Flood Inundation Mapping Science Web site at http://water.usgs.gov/osw/flood_inundation/, depict estimates of the areal extent and depth of flooding corresponding to selected water levels (stages) at the USGS streamgage White River at Spencer, Indiana (sta. no. 03357000). Current conditions for estimating near-real-time areas of inundation using USGS streamgage information may be obtained on the Internet at http://waterdata.usgs.gov/. National Weather Service (NWS)-forecasted peak-stage inforamation may be used in conjunction with the maps developed in this study to show predicted areas of flood inundation. In this study, flood profiles were computed for the stream reach by means of a one-dimensional step-backwater model. The model was calibrated by using the most current stage-discharge relation at the White River at Spencer, Indiana, streamgage and documented high-water marks from the flood of June 8, 2008. The hydraulic model was then used to compute 20 water-surface profiles for flood stages at 1-foot intervals referenced to the streamgage datum and ranging from the NWS action stage (9 feet) to the highest rated stage (28 feet) at the streamgage. The simulated water-surface profiles were then combined with a geographic information system digital elevation model (derived from Light Detection and Ranging (LiDAR) data) in order to delineate the area flooded at each water level. The availability of these maps along with Internet information regarding the current stage from the Spencer USGS streamgage and forecasted stream stages from the NWS will provide emergency management personnel and residents with information that is critical for flood response activities, such as evacuations and road closures, as well as for post-flood recovery efforts.

Indiana↗
USGS2012

Estimation of natural historical flows for the Manitowish River near Manitowish Waters, Wisconsin

The Wisconsin Department of Natural Resources is charged with oversight of dam operations throughout Wisconsin and is considering modifications to the operating orders for the Rest Lake Dam in Vilas County, Wisconsin. State law requires that the operation orders be tied to natural low flows at the dam. Because the presence of the dam confounds measurement of natural flows, the U.S. Geological Survey, in cooperation with the Wisconsin Department of Natural Resources, installed streamflow-gaging stations and developed two statistical methods to improve estimates of natural flows at the Rest Lake Dam. Two independent methods were used to estimate daily natural flow for the Manitowish River approximately 1 mile downstream of the Rest Lake Dam. The first method was an adjusted drainage-area ratio method, which used a regression analysis that related measured water yield (flow divided by watershed area) from short-term (2009–11) gaging stations upstream of the Manitowish Chain of Lakes to the water yield from two nearby long-term gaging stations in order to extend the flow record (1991–2011). In this approach, the computed flows into the Chain of Lakes at the upstream gaging stations were multiplied by a coefficient to account for the monthly hydrologic contributions (precipitation, evaporation, groundwater, and runoff) associated with the additional watershed area between the upstream gaging stations and the dam at the outlet of the Chain of Lakes (Rest Lake Dam). The second method used to estimate daily natural flow at the Rest Lake Dam was a water-budget approach, which used lake stage and dam outflow data provided by the dam operator. A water-budget model was constructed and then calibrated with an automated parameter-estimation program by matching simulated flow-duration statistics with measured flow-duration statistics at the upstream gaging stations. After calibration of the water-budget model, the model was used to compute natural flow at the dam from 1973 to 2011. Daily natural flows at the dam, as computed by the adjusted drainage-area ratio method and the water-budget method, were used to compute monthly flow-duration values for the period of historical data available for each method. Monthly flow-durations provide a means for evaluating the frequency and range in flows that have been observed for each month over the course of many years. Both methods described the pattern and timing of measured high-flow and low-flow events at the upstream gaging stations. The adjusted drainage-area ratio method generally had smaller residual errors across the full range of observed flows and had smaller monthly biases than the water-budget method. Although it is not possible to evaluate which method may be more "correct" for estimating monthly natural flows at the dam, comparisons between the results of each method indicate that the adjusted drainage-area ratio method may be susceptible to biases at high flows due to isolated storms outside of the Manitowish River watershed. Conversely, it appears that the water-budget method may be susceptible to biases at low flows because of its sensitivity to the accuracy of reported lake stage and outflows, as well as effects of upstream diversions that could not be fully compensated for with this method. Results from both methods are useful for understanding the natural flow patterns at the dam. Flows for both methods have similar patterns, with high median flows in spring and low median flows in late summer. Similarly, the range from monthly high-flow durations to low-flow durations increases during spring, decreases during summer, and increases again during fall. These seasonal patterns illustrate a challenge with interpreting a single value of natural low flow. That is, a natural low flow computed for September is not representative of a natural low flow in April. Moreover, alteration of natural flows caused by storing water in the Chain of Lakes during spring and releasing it in fall causes a change in the timing of high and low flows compared with natural conditions. That is, the lowest reported dam outflows occurred in spring and highest reported outflows occurred in fall, which is opposite the natural patterns.

Wisconsin↗
USGS1998

Yields and trends of nutrients and total suspended solids in nontidal areas of the Chesapeake Bay basin, 1985-96

Excessive concentrations of nutrients and suspended solids in water adversely affect water quality in the Chesapeake Bay. High levels of nutrients in the Bay result in algal blooms and suspended solids reduce water clarity, both of which decrease the amount of light reaching submerged aquatic vegetation (SAV). The die off and decomposition of algae and SAV deplete oxygen supplies in the water. Low dissolved oxygen (DO) levels (less than 5.0 milligrams per liter for aquatic life, U.S. Environmental Protection Agency, 1986) can lead to fish kills and stress other living resources in the Bay. In 1987, the Chesapeake Bay Agreement called for a 40-percent reduction in the amount of controllable nutrients reaching the Chesapeake Bay by the year 2000. This goal was based on results of computer simulations that predicted that periods of low DO would be reduced or eliminated if nutrient inputs to the Bay were reduced by that amount. In an effort to achieve that goal, nutrient-reduction strategies, including banning phosphate detergents, upgrading sewagetreatment plants, controlling runoff from agricultural and urban areas, and preserving forest and wetland areas (Zynjuk, 1995), were implemented in many areas of the basin to help reduce nutrient inputs to the Bay. In 1997, a basinwide reevaluation of the 40-percent reduction goal was initiated to determine if that goal is achievable and to identify and document any changes in water quality and living resources in response to nutrient-reduction strategies. In support of this reevaluation, the U.S. Geological Survey (USGS) designed a database and retrieved water-quality data from approximately 1,300 nontidal stream sites in the Chesapeake Bay Basin (Langland and others, 1995). At 84 of the 1,300 sites, where sufficient data were available, trends, yields, and annual loads of nutrients and suspended solids were estimated for 1985 through 1996. This report presents: (1) spatial distribution of available nutrient and suspended-solids data for the 84 sites, (2) yields of nutrients and total suspended solids, and (3) trends in concentrations of nutrients and total suspended solids. Results presented here are limited to analyses for total nitrogen (TN), nitrate nitrogen (NO3), total phosphorus (TP), and total suspended solids (TSS).

Water-Resources Investigations Report↗
USGS1979

Beach-cusp formation

Field experiments on beach-cusp formation were undertaken to document how the cuspate form develops and to test the edge-wave hypothesis on the uniform spacing of cusps. These involved observations of cusps forming from an initially plane foreshore. The cuspate form was observed to be a product of swash modification of an intertidal beach ridge as follows. A ridge, cut by a series of channels quasi-equally spaced along its length, was deposited onto the lower foreshore. The ridge migrated shoreward with flood tide, while the longshore positions of the channels remained fixed. On ebb tide, changes in swash circulation over the ridge allowed the upwash to flow shoreward through the channels and the channel mouths were eroded progressively wider until adjacent mouths met, effecting a cuspate shape. Measured spacings of cusps, ranging in size from less than 1 m to more than 12 m, agree well with computed spacings due to either zero-mode subharmonic or zero-mode synchronous edge waves. Edge-wave-induced longshore variations in run up will cause water ponded behind a ridge to converge at points of low swash and flow seaward as relatively narrow currents eroding channels spaced at one edge-wave wavelength for synchronous edge waves or one half wavelength for subharmonic edge waves. The channels are subsequently modified into cusp troughs as described above.

Marine Geology↗
USGS1973

Thermochemical approximations for sulfosalts

Most sulfosalts may be regarded as intermediate phases on joins between simple sulfide components (e.g., all lead sulfbismuthinides lie on the PbS-Bi 2 S 3 join). Many of the structures are characterized by subunits whose individual structures are similar to those of the component simple sulfides (e.g., galena-like and stibnite-like layers in the lead sulfantimonides). Therefore, as a first approximation one may estimate the properties of many sulfosalts in terms of mixtures of the simple sulfides.Recent work has shown that the free energy of reaction from the end-member sulfides, delta G m , for more than 20 sulfosalts is usually less negative than the hypothetical ideal free energy of mixing and that the standard free energy of formation, delta G degrees , per gram atom of sulfur in the formula may be represented as:delta G degrees = (N a delta G a degrees + . . . N i delta G i [degree) + (1.2 + or - 0.8)(N a RT ln N a + . . . N i RT ln N i )where N i is the mole fraction of the i-th simple sulfide component, R is the gas constant, and T is temperature in kelvins. The first term is far larger than the second. Estimates made for compounds in which the structural environment for the metals is quite different from that in the end-member sulfides, e.g., enargite, are subject to the greatest uncertainty.The estimated free energies may permit prediction of solubilities to a precision sufficient for many purposes, e.g., for H. C. Helgeson's computer-modeled hydrothermal systems. One may introduce some predictive capability into experimental design and anticipate some aspects of phase diagrams. This is especially true for redox reactions such as the behavior of proustite in the oxidized zone or the partial reduction of jamesonite to antimony + galena + pyrrhotite. However, other aspects, such as the prediction of the configuration of joins, e.g., PbS-As 2 S 3 , requires greater precision than the present rough estimates.

Economic Geology↗
USGS2012

Updates to watershed modeling in the Potholes Reservoir basin, Washington-a supplement to Scientific Investigation Report 2009-5081

A previous collaborative effort between the U.S. Geological Survey and the Bureau of Reclamation resulted in a watershed model for four watersheds that discharge into Potholes Reservoir, Washington. Since the model was constructed, two new meteorological sites have been established that provide more reliable real-time information. The Bureau of Reclamation was interested in incorporating this new information into the existing watershed model developed in 2009, and adding measured snowpack information to update simulated results and to improve forecasts of runoff. This report includes descriptions of procedures to aid a user in making model runs, including a description of the Object User Interface for the watershed model with details on specific keystrokes to generate model runs for the contributing basins. A new real-time, data-gathering computer program automates the creation of the model input files and includes the new meteorological sites. The 2009 watershed model was updated with the new sites and validated by comparing simulated results to measured data. As in the previous study, the updated model (2012 model) does a poor job of simulating individual storms, but a reasonably good job of simulating seasonal runoff volumes. At three streamflow-gaging stations, the January 1 to June 30 retrospective forecasts of runoff volume for years 2010 and 2011 were within 40 percent of the measured runoff volume for five of the six comparisons, ranging from -39.4 to 60.3 percent difference. A procedure for collecting measured snowpack data and using the data in the watershed model for forecast model runs, based on the Ensemble Streamflow Prediction method, is described, with an example that uses 2004 snow-survey data.

Washington↗
USGS2013

Bathymetric surveys of selected lakes in Missouri--2000-2008

Years of sediment accumulation and abnormally dry conditions in the Midwest in 1999 and 2000 led to the water level decline of many water-supply lakes in Missouri, and caused renewed interest in modernizing outdated area/volume tables for these lakes. The U.S. Geological Survey, in cooperation with the Missouri Department of Natural Resources and the U.S. Army Corps of Engineers, surveyed the bathymetry of 51 lakes in Missouri from July 2000 to May 2008. The data were used to provide water managers with area/volume tables and bathymetric maps of the lakes at the time of the surveys. In 50 of the lakes, bathymetric surveys were made using a boat-mounted single-beam survey-grade fathometer. In Clearwater Lake, bathymetric data were collected primarily using a boat-mounted survey-grade multibeam fathometer, and some bathymetric data were collected using a single-beam fathometer in areas of the lake that were inaccessible to the multibeam fathometer. Data processing, area/volume table computation, and bathymetric map production were completed for each lake.

Missouri↗
USGS2009

Analysis of Water-Quality Trends for Selected Streams in the Water Chemistry Monitoring Program, Michigan, 1998-2005

In 1998, the Michigan Department of Environmental Quality and the U.S. Geological Survey began a long-term monitoring program to evaluate the water quality of most watersheds in Michigan. Major goals of this Water-Chemistry Monitoring Program were to identify streams exceeding or not meeting State or Federal water-quality standards and to assess if constituent concentrations reflecting water quality in these streams were increasing or decreasing over time. As part of this program, water-quality data collected from 1998 to 2005 were analyzed to identify potential trends. Sixteen water-quality constituents were analyzed at 31 sites across Michigan, 28 of which had sufficient data to analyze for trends. Trend analysis on the various water-quality data was done using the uncensored Seasonal Kendall test within the computer program ESTREND. The most prevalent trend detected throughout the state was for chloride. Chloride trends were detected at 8 of the 28 sites; trends at 7 sites were increasing and the trend at 1 site was decreasing. Although no trends were detected for various nitrogen species or phosphorus, these constituents were detected at levels greater than the U.S. Environmental Protection Agency recommendations for nutrients in water. The results of the trend analysis will help to establish a baseline to evaluate future changes in water quality in Michigan streams.

Scientific Investigations Report↗
USGS1982

Water-quality assessment of White River between Lake Sequoyah and Beaver Reservoir, Washington County, Arkansas

The Arkansas Department of Pollution Control and Ecology and U.S. Geological Survey conducted a water quality assessment be made of the White River and, that a steady-state digital model be calibrated and used as a tool for simulating changes in nutrient loading. The city of Fayetteville 's wastewater-treatment plant is the only point-source discharger of waste effluent to the river. Data collected during synoptic surveys downstream from the wastewater-treatment plan indicate that temperature, dissolved oxygen, dissolved solids, un-ionized ammonia, total phosphorus, and floating solids and depositable materials did not meet Arkansas stream standards. Nutrient loadings below the treatment plant result in dissolved oxygen concentrations as low as 0.0 milligrams per liter. Biological surveys found low macroinvertebrate organism diversity and numerous dead fish. Computed dissolved oxygen deficits indicate that benthic demands are the most significant oxygen sinks in the river downstream from the wastewater-treatment plant. Benthic oxygen demands range from 2.8 to 11.0 grams per meter squared per day. Model projections indicate that for 7-day, 10-year low-flow conditions and water temperature of 29 degrees Celsius, daily average dissolved oxygen concentrations of 6.0 milligrams per liter can be maintained downstream from the wastewater-treatment plant if effluent concentrations of ultimate carbonaceous biochemical oxygen demand and ammonia nitrogen are 7.5 (5.0 5-day demand) and 2 milligrams per liter respectively. Model sensitivity analysis indicate that dissolved oxygen concentrations were most sensitive to changes in stream temperature. (USGS)

Water-Resources Investigations Report↗
USGS1984

Sedimentation survey of Fena Reservoir, Guam, Mariana Islands, 1979

Fena Reservoir, in south-central Guam, was constructed in 1950-51 to provide a dependable water supply for the U.S. Navy. At the request of the U.S. Navy, the U.S. Geological Survey conducted a sedimentation survey of the Fena Reservoir during the months of November and December 1979. The sedimentation survey showed that at the spillway elevation, the reservoir has a surface area of 195 acres and a volume of 7,863 acre-ft. Data from a network of 30 triangulation stations and 32 cross sections indicated a decrease of 440 acre-feet in reservoir capacity since 1949 due to the accumulation of sediment. Area capacity curves for 1949, 1973, and 1979 and a bathymetric map of the reservoir were constructed. The combination of denser water due to lower temperature and suspended sediment load appears to create a density current within the reservoir. Particle size analyses and unit-weight computation are provided to define the physical characteristics of the accumulated sediment. (Author 's abstract)

Water-Resources Investigations Report↗
USGS1999

Geochemical data for stream-sediment, heavy-mineral-concentrate, and rock samples collected from the Fortyseven Creek gold-arsenic-antimony-tungsten prospect, southwestern Alaska

In the summer of 1991, we conducted a reconnaissance geochemical survey around the Fortyseven Creek Au-As-Sb-W prospect that is located in the southwestern part of the Sleetmute quadrangle. At that time, this project was a small part of a more comprehensive Alaska Mineral Resource Assessment Program (AMRAP) study of the Sleemute quadrangle. AMRAP studies were conducted by the U.S. Geological Survey (USGS) to fulfill requirements of the Alaska National Interests Lands Conservation Act (Public Law 96-487, 1980) to survey certain federal lands to determine their mineral potential. Although AMRAP is no longer in operation, this study represents a small topical study that was conducted during the Sleetmute quadrangle AMRAP study. The objective of the Fortyseven Creek work was to characterize the geochemistry of samples collected downstream from the Fortyseven Creek prospect, as well as mineralized and altered rock samples collected from the prospect. In this report, we describe the samples collected in 1991, the methods used for the analysis of the samples, and the geochemical data for these samples. The data in this report are also available in digital form on computer diskette in Gray and others (1999). An interpretation of these data appears in Gray and others (1998).

Alaska↗
USGS2018

Development of a hydraulic model and flood-inundation maps for the Wabash River near the Interstate 64 Bridge near Grayville, Illinois

A two-dimensional hydraulic model and digital flood‑inundation maps were developed for a 30-mile reach of the Wabash River near the Interstate 64 Bridge near Grayville, Illinois. The flood-inundation maps, which can be accessed through the U.S. Geological Survey (USGS) Flood Inundation Mapping Science web site at http://water.usgs.gov/osw/flood_inundation/ , depict estimates of the areal extent and depth of flooding corresponding to selected water levels (stages) at the USGS streamgage on the Wabash River at Mount Carmel, Ill (USGS station number 03377500). Near-real-time stages at this streamgage may be obtained on the internet from the USGS National Water Information System at http://waterdata.usgs.gov/ or the National Weather Service (NWS) Advanced Hydrologic Prediction Service (AHPS) at http://water.weather.gov/ahps/ , which also forecasts flood hydrographs at this site (NWS AHPS site MCRI2). The NWS AHPS forecasts peak stage information that may be used with the maps developed in this study to show predicted areas of flood inundation. Flood elevations were computed for the Wabash River reach by means of a two-dimensional, finite-volume numerical modeling application for river hydraulics. The hydraulic model was calibrated by using global positioning system measurements of water-surface elevation and the current stage-discharge relation at both USGS streamgage 03377500, Wabash River at Mount Carmel, Ill., and USGS streamgage 03378500, Wabash River at New Harmony, Indiana. The calibrated hydraulic model was then used to compute 27 water-surface elevations for flood stages at 1-foot (ft) intervals referenced to the streamgage datum and ranging from less than the action stage (9 ft) to the highest stage (35 ft) of the current stage-discharge rating curve. The simulated water‑surface elevations were then combined with a geographic information system digital elevation model, derived from light detection and ranging data, to delineate the area flooded at each water level. The availability of these maps, along with information on the internet regarding current stage from the USGS streamgage at Mount Carmel, Ill., and forecasted stream stages from the NWS AHPS, provides emergency management personnel and residents with information that is critical for flood-response activities such as evacuations and road closures, as well as for postflood recovery efforts.

Illinois↗
USGS2004

Hydrogeology and quality of ground water in Orange County, Florida

Ground water is the main source of water supply in central Florida and is critical for aquatic habitats and human consumption. To provide a better understanding for the conservation, development, and management of the water resources of Orange County, Florida, a study of the hydrogeologic framework, water budget, and ground-water quality characteristics was conducted from 1998 through 2002. The study also included extensive analyses of the surface-water resources, published as a separate report. An increase in population from about 264,000 in 1960 to 896,000 in 2000 and subsequent urban growth throughout this region has been accompanied by a substantial increase in water use. Total ground-water use in Orange County increased from about 82 million gallons per day in 1965 to about 287 million gallons per day in 2000. The hydrogeology of Orange County consists of three major hydrogeologic units: the surficial aquifer system, the intermediate confining unit, and the Floridan aquifer system. Data were compiled from 634 sites to construct hydrogeologic maps and sections of Orange County. Water-level elevations measured in 23 wells tapping the surficial aquifer system ranged from about 10.6 feet in eastern Orange County to 123.8 feet above NGVD 29 in northwestern Orange County from March 2000 through September 2001. Water levels also were measured in 14 wells tapping the Upper Floridan aquifer. Water levels fluctuate over time from seasonal and annual variations in rainfall; however, water levels in a number of wells tapping the Upper Floridan aquifer have declined over time. Withdrawal of ground water from the aquifers by pumping probably is causing the declines because the average annual precipitation rate has not changed substantially in central Florida since the 1930s, although yearly rates can vary. A generalized water budget was computed for Orange County from 1991 to 2000. Average rates for the 10-year period for the following budget components were computed based on reported measurements or estimates: precipitation was 53 inches per year (in/yr), runoff was 11 in/yr, spring discharge was 2 in/yr, and net lateral subsurface outflow and exported water was 1 in/yr. Evapotranspiration was 39 in/yr, which was calculated as the residual of the water-budget analysis, assuming changes in storage were negligible. Water-quality samples were collected from April 1999 through May 2001 from a total of 26 wells tapping the surficial aquifer system, 1 well tapping the intermediate confining unit, 24 wells tapping the Upper Floridan aquifer, 2 springs issuing from the Upper Floridan aquifer, and 8 wells tapping the Lower Floridan aquifer. These data were supplemented with existing water-quality data collected by the U.S. Geological Survey and St. Johns River Water Management District. Concentrations of total dissolved solids, sulfate, and chloride in samples from the surficial aquifer system generally were low. Concentrations of nitrate were higher in samples from the surficial aquifer system than in samples from the Upper Floridan or Lower Floridan aquifers, probably as a result of agricultural and residential land use. Water type throughout most of the Upper Floridan and Lower Floridan aquifers was calcium or calcium-magnesium bicarbonate, probably as a result of dissolution of the carbonate rocks. Water type in both the surficial and Floridan aquifer systems in eastern Orange County is sodium chloride. Concentrations of total dissolved solids, sulfate, and chloride in the aquifers increase toward eastern Orange County. Data from 16 of 24 wells in eastern Orange County with long-term water-quality records indicated distinct increases in concentrations of chloride over time. The increases probably are related to withdrawal of ground water at the Cocoa well field, causing an upwelling of deeper, more saline water. The most commonly detected trace elements were aluminum, barium, boron, iron, manganese, and strontium. In addition, arse

Water-Resources Investigations Report↗
USGS1995

Data for and adjusted regional regression models of volume and quality of urban storm-water runoff in Boise and Garden City, Idaho, 1993-94

The U.S. Environmental Protection Agency requires information on the volume and quality of urban storm-water runoff to apply for a permit to discharge this water into the Boise River under the National Pollutant Discharge Elimination System Program. Concentrations of selected chemical constituents in storm runoff were determined from samples collected at four storm-sewer outfalls in Boise from October 1993 through June 1994 and at one outfall in Garden City from September through October 1994. Samples were analyzed for specific conductance, pH, alkalinity, water temperature, oxygen demand, fecal indicator bacteria, major ions, dissolved and suspended solids, nutrients, trace elements, and numerous organic compounds. The measurement of storm-runoff volume and mean concentrations of constituents were used to estimate storm-runoff loads. Previously developed U.S. Geological Survey regional regression models of runoff and 11 chemical constituents were evaluated to assess their suitability for use in urban areas in Boise and Garden City. Data collected in the study area were used to develop adjusted regional models of storm-runoff volumes and mean concentrations and loads of chemical oxygen demand, dissolved and suspended solids, total nitrogen and total ammonia plus organic nitrogen as nitrogen, total and dissolved phosphorus, and total recoverable cadmium, copper, lead, and zinc. Explanatory variables used in these models were drainage area, impervious area, land-use information, and precipitation data. Mean annual runoff volume and loads at the five outfalls were estimated from 904 individual storms during 1976 through 1993. Two methods were used to compute individual storm loads. The first method used adjusted regional models of storm loads and the second used adjusted regional models for mean concentration and runoff volume. For large storms, the first method seemed to produce excessively high loads for some constituents and the second method provided more reliable results for all constituents except suspended solids. The first method provided more reliable results for large storms for suspended solids.

Idaho↗
USGS2024

Automatic identification and quantification of volcanic hotspots in Alaska using HotLINK: The hotspot learning and identification network

An increase in volcanic thermal emissions can indicate subsurface and surface processes that precede, or coincide with, volcanic eruptions. Space-borne infrared sensors can detect hotspots—defined here as localized volcanic thermal emissions—in near-real-time. However, automatic hotspot detection systems are needed to efficiently analyze the large quantities of data produced. While hotspots have been automatically detected for over 20 years with simple thresholding algorithms, new computer vision technologies, such as convolutional neural networks (CNNs), can enable improved detection capabilities. Here we introduce HotLINK: the Hotspot Learning and Identification Network, a CNN trained to detect hotspots with a dataset of −3,800 satellite-based, Visible Infrared Imaging Radiometer Suite (VIIRS) images from Mount Veniaminof and Mount Cleveland volcanoes, Alaska. We find that our model achieves an accuracy of 96% (F1-score 0.92) when evaluated on −1,700 unseen images from the same volcanoes, and 95% (F1-score 0.67) when evaluated on −3,000 images from six additional Alaska volcanoes (Augustine Volcano, Bogoslof Island, Okmok Caldera, Pavlof Volcano, Redoubt Volcano, Shishaldin Volcano). In comparison with an existing threshold-based hotspot detection algorithm, MIROVA (Coppola et al., Geological Society, London, Special Publications, 2016, 426, 181–205), our model detects 22% more hotspots and produces 12% fewer false positives. Additional testing on −700 labeled Moderate Resolution Imaging Spectroradiometer (MODIS) images from Mount Veniaminof demonstrates that our model is applicable to this sensor’s data as well, achieving an accuracy of 98% (F1-score 0.95). We apply HotLINK to 10 years of VIIRS data and 22 years of MODIS data for the eight aforementioned Alaska volcanoes and calculate the radiative power of detected hotspots. From these time series we find that HotLINK accurately characterizes background and eruptive periods, similar to MIROVA, but also detects more subtle warming signals, potentially related to volcanic unrest. We identify three advantages to our model over its predecessors: 1) the ability to detect more subtle volcanic hotspots and produce fewer false positives, especially in daytime images; 2) probabilistic predictions provide a measure of detection confidence; and 3) its transferability, i.e., the successful application to multiple sensors and multiple volcanoes without the need for threshold tuning, suggesting the potential for global application.

Alaska↗
USGS2016

Groundwater hydrology and estimation of horizontal groundwater flux from the Rio Grande at selected locations in Albuquerque, New Mexico, 2009–10

The Albuquerque area of New Mexico has two principal sources of water: (1) groundwater from the Santa Fe Group aquifer system, and (2) surface water from the Rio Grande. From 1960 to 2002, pumping from the Santa Fe Group aquifer system caused groundwater levels to decline more than 120 feet while water-level declines along the Rio Grande in Albuquerque were generally less than 40 feet. These differences in water-level declines in the Albuquerque area have resulted in a great deal of interest in quantifying the river-aquifer interaction associated with the Rio Grande. In 2003, the U.S. Geological Survey, in cooperation with the Bureau of Reclamation, acting as fiscal agent for the Middle Rio Grande Endangered Species Collaborative Program, and the U.S. Army Corps of Engineers, began a study to characterize the hydrogeology of the Rio Grande inner valley alluvial aquifer in the Albuquerque area of New Mexico. The study provides hydrologic data in order to enhance the understanding of rates of water leakage from the Rio Grande to the alluvial aquifer, groundwater flow through the aquifer, and discharge of water from the aquifer to riverside drains. The study area extends about 20 miles along the Rio Grande in the Albuquerque area. Piezometers and surface-water gages were installed in paired transects at eight locations. Nested piezometers, completed at various depths in the alluvial aquifer, and surface-water gages, installed in the Rio Grande and riverside drains, were instrumented with pressure transducers. Water-level and water-temperature data were collected from 2009 to 2010. Water levels from the piezometers indicated that groundwater movement was usually away from the river towards the riverside drains. Annual mean horizontal groundwater gradients in the inner valley alluvial aquifer ranged from 0.0024 (I-25 East) to 0.0144 (Pajarito East). The median hydraulic conductivity values of the inner valley alluvial aquifer, determined from slug tests, ranged from 30 feet per day (ft/d) (Montaño) to 120 ft/d (Central) for paired transects, with a median hydraulic conductivity for all transects of 50 ft/d. Daily mean groundwater fluxes from the river through the inner valley alluvial aquifer computed using Darcy’s Law and the slug test results ranged from about 0.01 ft/d (Montaño West) to between 1.0 and 2.0 ft/d (Central East). Median annual groundwater fluxes from the river through the inner valley alluvial aquifer determined using the Suzuki-Stallman method was greatest at Alameda East (0.50 ft/d) and lowest at Alameda West (0.25 ft/d). The results from both methods agreed reasonably well. Seepage investigations conducted by measuring discharge in the east and west riverside drains provided information for computing changes in flow within the drains and for evaluating results from Darcy’s Law and Suzuki-Stallman method flux calculations. Discharge measured in the east riverside drain between the Barelas Bridge and the I-25 bridge indicated that the flow in the east riverside drain increased by an average of 56.5 cubic feet per day per linear foot (ft 3 /d/ft) of drain. Discharge measured in the west riverside drain between the Central bridge and the I-25 bridge indicated that flow increased between west drain miles 0 and 4, an average of 53.8 ft 3 /d/ft of drain, and that flow increased between west drain miles 7 and 10, an average of 44.9 ft 3 /d/ft of drain. In comparison to the seepage measurement results, the groundwater fluxes from the river through the inner valley alluvial aquifer calculated from Darcy’s Law (q slug ) and by the Suzuki-Stallman method (q heat ) would account for 20–36 percent or 53–95 percent, respectively, of the total flow in the east riverside drain and 22–31 percent or 19–26 percent, respectively, of the total flow in the west drain. These results indicate that the drains likely also receive water from outside the inner valley. The spatial variability of horizontal hydraulic gradients and groundwater fluxes can be primarily attributed to variability in the distances between the river and riverside drains throughout the study area and geologic heterogeneities in the alluvial aquifer. Temporal variability in the water levels, which control the horizontal hydraulic gradients and fluxes between the Rio Grande and the riverside drains, can be primarily attributed to seasonal fluctuations in river stage and irrigation practices.

New Mexico↗