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At least 451 records · Page 25Linked to original sources
USGS2011

Effectiveness of catch basins equipped with hoods in retaining gross solids and hydrocarbons in highway runoff, Southeast Expressway, Boston, Massachusetts, 2008-09

Stormwater mobilizes litter and other debris along the roadway where it is transported to the highway drainage systems. Initial treatment for stormwater runoff typically is provided by catch basins in highway settings. Modification of catch basins to include hoods that cover the catch-basin outlet is intended to enhance catch-basin performance by retaining floatable debris and various hydrophobic organic compounds that tend to float on the water surface within the sump of the catch basin. The effectiveness of six deep-sump off-line catch basins equipped with hoods in reducing the mass of gross solids greater than 0.25 inches in diameter and concentrations of oil and grease (OG) and total petroleum hydrocarbons (TPH) was examined along the Southeast Expressway, in Boston, Massachusetts. Two deep-sump catch basins were equipped with cast-iron hoods. Three were equipped with molded plastic hoods, known as an Eliminator, and a single catch basin was equipped with a fiberglass anti-siphoning hood, known as a Snout. Samples of gross solids greater than 0.25 inches in diameter, excluding gravel and metallic materials, were routinely collected for a 6-month period from a collection structure mounted at the end of each catch-basin outlet pipe. After about 6 months, all floatable, saturated low-density and high-density solids were removed from each catch basin. In addition to the collection of samples of gross solids, samples of sump water from five catch basins and flow-weighted composite samples of stormwater from the outlet of one catch basin were collected and analyzed for concentrations of OG and TPH. A mass balance approach was used to assess the effectiveness of each catch basin equipped with a hood in retaining gross solids. The effectiveness of the deep-sump catch basins fitted with one of three types of hoods in retaining gross solids ranged from 27 to 52 percent. From 45 to 90 percent of the gross solids collected from the catch-basin sumps were composed of materials made of high-density plastics that did not float in water, and as a result, the effect that the catch-basin hoods had on these materials likely was marginal. The effectiveness for the deep-sump hooded catch basins, excluding the mass of high-density materials identified in the solids collected from the outlet pipe and the sump of the catch basins, ranged from 13 to 38 percent. The effectiveness for each catch basin, based solely on the material that remained floating at the end of the monitoring period, was less than 11 percent; however, these values likely underestimate the effectiveness of the hooded catch basins because much of the low-density material collected from the sumps may have been retained as floatable material before it was saturated and settled during non-storm conditions. The effectiveness of the catch basins equipped with hoods in reducing gross solids was not greatly different among the three types of hoods tested in this study. Concentrations of OG and TPH collected from the water surface of the catch-basins varied from catch basin to catch basin and were similar to concentrations of flow-weighted composite samples collected during storms. Comparisons indicate concentrations of OG and TPH in flow-weighted composite samples collected at the outlet of a catch basin equipped with an Eliminator hood were not substantially different from concentrations of the respective constituents in flow-weighted composite samples collected during a previous study from catch basins containing cast-iron hoods in the same study area. The similarity between these flow-weighted concentrations and the concentrations of the respective constituents in a vertical profile sample collected from the catch-basin sump indicates that OG and TPH are emulsified in the sump of each catch basin during storms and circumvent the hoods.

Massachusetts↗
USGS2021

Instruments, methods, rationale, and derived data used to quantify and compare the trapping efficiencies of four types of pressure-difference bedload samplers

Bedload and ancillary data were collected to calculate and compare the bedload trapping efficiencies of four types of pressure-difference bedload samplers as part of episodic, sediment-recirculating flume experiments at the St. Anthony Falls Laboratory, University of Minnesota, Minneapolis, in January–March 2006. The bedload-sampler experiments, which were conceived, organized, and led by the U.S. Geological Survey’s Office of Surface Water, were part of a broader suite of experiments performed in the rectangular, concrete-lined, sediment-recirculating Main Channel Facility (“main channel flume”). Collectively referred to as “StreamLab06,” the experiments were conducted under the auspices of the National Center for Earth-Surface Dynamics, University of Minnesota. Four pressure-difference-type bedload samplers—a standard Helley-Smith, US BLH-84, Elwha, and Toutle River-2—were deployed by using hand-held rods in the main flume in a series of trials during steady flows as part of the first two of seven phases of the StreamLab06 experiments. The Phase I flows were released over a sand bed. Gravel composed the bed during the Phase II flows. Bedload samples were collected during flows ranging from 2.0 cubic meters per second (near the incipient motion of bed material) to 5.5 cubic meters per second. A total of 2,030 bedload samples were collected—1,000 as part of 19 sand-bed trials, and 1,030 as part of 27 gravel-bed trials. Bedload was captured in five contiguous weigh drums inside a slot spanning the full width of the main flume channel 8.5 meters downstream from the cross-section in which the bedload samplers were deployed. The contents of each drum were automatically weighed and recorded as a time series about every 1.1 seconds. Each drum automatically, independently, and episodically dumped its contents into the bottom of the slot upon the accumulation of a pre-determined mass of entrapped sediment, after which the drum continued to capture and weigh bedload. An auger at the bottom of the slot evacuated the accumulating sediment to a side-channel pump that piped the captured sediments upstream and discharged them back to the flume. Bedload-transport rates were calculated from measurements of the masses of material trapped by the bedload samplers and from the data produced by the automated bedload capture-and-weigh system of the main channel flume. These data were used to compute at-a-point and mean bedload-transport rates for subsequent use in developing bedload-trapping efficiency (calibration) coefficients for each bedload sampler and for comparing the relative trapping efficiencies of the manually deployed bedload samplers. The data were collected to enable the use of several computational methods for deriving bedload-trapping coefficients. Continuous ancillary data including stage, water discharge, and water temperature were automatically collected and stored. Flow depths were manually measured and recorded concurrent with each at-a-point bedload-sampler deployment. Other information obtained during parts of the experiments included longitudinal water-surface slope, bedload particle-size distributions, and suspended-sediment concentrations and percent sand analyzed from samples collected by depth integration with a US DH-48 isokinetic suspended-sediment sampler. This report describes the types and availability of the bedload and ancillary data derived through the StreamLab06 experiments. The data are available from the St. Anthony Falls Laboratory and the U.S. Geological Survey through a data release. Also included are selected descriptive and historical information as well as the background, experimental design, experimental caveats, and other factors relevant to the production of the bedload-transport and ancillary data produced through Phases I and II of the StreamLab06 experiments.

Open-File Report↗
USGS2025

Real-time oil spill concentration assessment through fluorescence imaging and deep learning

Oil spills may pose severe ecological and socioeconomic threats, necessitating rapid and accurate environmental assessment. Traditional assessment methods used to determine the extent of a spill including gas chromatography-mass spectrometry, satellite imaging, and visual surveys, are often time-consuming, expensive, and limited by weather conditions or sampling constraints. Furthermore, these methods frequently struggle to provide real-time data crucial for prompt decision-making during spill emergencies. This study addresses these limitations by combining fluorescence imaging, deep learning, a mobile application, and a data management system for automated and real-time oil spill assessment. Our approach leverages a convolutional neural network architecture for feature extraction coupled with a custom regression model, trained and evaluated on a self-curated comprehensive dataset of 1,530 fluorescence images from two distinct oil types, a napthalenic crude oil and an aromatic-napthalenic crude oil, at concentrations ranging from 0 to 500 mg/L. The proposed approach demonstrates superior performance compared to both traditional machine learning models and more complex deep learning architectures, achieving an R² score of 0.9958 and RMSE of 9.28. The application enables rapid, cost-effective field measurements with robust data tracking and analysis capabilities. This research advances oil spill monitoring technology with a scalable solution that balances accuracy, speed, and accessibility for real-time environmental assessment and emergency response.

Journal of Hazardous Materials↗
USGS2003

Analysis of aquifer mineralization by paleodrainage channels

Mineralization of groundwater resources is a problem in south-central Kansas, due to the penetration of saline water from Permian bedrock formations into the overlying alluvial aquifer. One of the mechanisms involved in the mineralization involves small bedrock features of high permeability located in places occupied by streams and rivers in past geological eras. These geological features are termed 'paleodrainage channels'. The permeability of the overlying aquifer can be significantly smaller than that of the channel fill material. The comparatively fast migration of saline water through these channels of high permeability is associated with the transfer of minerals into the overlying freshwater aquifer. This study applies a set of boundary layer approaches to quantify the process of mineral transfer from the channels into the aquifer. The methods used in the present study provide quick estimation and evaluation of the dilution of the channel flow, as well as mineral concentration profile changes in the mineralized zone created in the overlying aquifer. More generally, the method can also be useful for the analysis and evaluation of various types of groundwater contamination in heterogeneous aquifers. The application of the method is exemplified by a complete set of calculations characterizing the possible mineralization process at a specific channel in south central Kansas. Sensitivity analyses are performed and provide information about the importance of the various parameters that affect the mineralization process. Some possible scenarios for the aquifer mineralization phenomena are described and evaluated. It is shown that the channel mineralization may create either several stream tubes of the aquifer with high mineral concentration, or many stream tubes mineralized to a lesser extent. Characteristics of these two patterns of aquifer mineralization are quantified and discussed. ?? 2003 Published by Elsevier Science B.V.

Journal of Hydrology↗
USGS2022

Characterization of subsurface conditions and recharge at the irrigated four-plex baseball field, Fort Irwin National Training Center, California, 2018–20

The U.S. Geological Survey performed subsurface and geophysical site characterization of the irrigated four-plex baseball field in the Langford Valley–Irwin Groundwater Subbasin, as part of a research study in cooperation with the U.S. Environmental Protection Agency, the Agricultural Research Service, and the Fort Irwin National Training Center, California. To help meet future demands, the Fort Irwin National Training Center is evaluating the efficacy of gravity-fed drywells to enhance storm-water recharge into the Langford Valley–Irwin Groundwater Subbasin by bypassing fine-grained, less permeable deposits between land surface and the water table. The amount, rate, and location of recharge beneath an irrigated baseball field in the groundwater basin at the Fort Irwin National Training Center is not well understood, so data were collected using physical and geophysical techniques to characterize subsurface materials, geologic controls, and the vertical movement of water through the unsaturated zone to the water table near the drywell at the Fort Irwin National Training Center. Based on the data collected and interpreted from these techniques, several fine-grained deposits were identified. Although these deposits appear to impede the downward movement of water through the unsaturated zone locally, they are not laterally continuous, and water appears to continue to move downward when it reaches the edges of the deposits. These data will help managers evaluate recharge at the site and determine if the use of gravity-fed drywells enhances recharge from surface runoff.

California↗
USGS2018

Burn severity controls on postfire Araucaria‐Nothofagus regeneration in the Andean Cordillera

Aim The aim of the study was to investigate postfire regeneration patterns of Araucaria‐Nothofagus forests on the west slope of the Andes; to evaluate the relationship between remotely sensed burn severity and forest mortality; and to assess controls of burn severity on forest response at local spatio‐temporal scales. Location Araucanía region in the western Andean Range of south‐central Chile where fire occurred during the 2001–2002 season. Methods Sampling of prefire stand structure and postfire vegetation response was performed along a burn severity gradient a decade after the fire. We evaluated the relationship between field‐measured tree mortality and satellite‐derived burn severity using a generalized linear model. We fit zero‐inflated mixture models to regeneration data of each genus to assess the importance of abiotic variables, stand characteristics, and biotic interactions. Results The relative version of the delta Normalized Burn Ratio explained 85% of the variability in canopy mortality. Nearly 12,000 hectares burned; the majority at high severity (67%). Regeneration densities of both genera were lower at higher levels of burn severity and higher with greater total basal area (live, dead, and down trees). The relative effect size of burn severity on regeneration was nearly twice as large for Nothofagus , which suggests information legacies of Araucaria have cascading effects on postdisturbance material legacies. Main conclusions Araucaria‐Nothofagus mortality from wildfire can be readily mapped using satellite‐derived burn severity. Although environmental site characteristics and biotic interactions mediate regeneration, basal area, and burn severity are the main mechanisms controlling regeneration. Forest refugia and postfire regeneration are vulnerable to recurrent fire. Therefore, we expect future fire (either increased severity or frequency), driven by landscape level changes, as a potential mechanism that can reduce local resilience of these forests as initial postfire material legacies (e.g., refugia and regeneration) are removed from the landscape. Our findings highlight an approach to quantify important attributes of forest disturbance and refugia, and identify areas for monitoring postdisturbance regeneration as the forests throughout south‐central Chile and Argentina face a multitude of potential change agents.

Journal of Biogeography↗
USGS1996

Improved method for measuring water imbibition rates on low-permeability porous media

Existing methods for measuring water imbibition rates are inadequate when imbibition rates are small (e.g., clay soils and many igneous rocks). We developed an improved laboratory method for performing imbibition measurements on soil or rock cores with a wide range of hydraulic properties. Core specimens are suspended from an electronic strain gauge (load cell) in a closed chamber while maintaining the lower end of the core in contact with a free water surface in a constant water level reservoir. The upper end of the core is open to the atmosphere. During imbibition, mass increase of the core is recorded continuously by a datalogger that converts the load cell voltage signal into mass units using a calibration curve. Computer automation allows imbibition rate measurement on as many as eight cores simultaneously and independently. Performance of each component of the imbibition apparatus was evaluated using a set of rock cores (2.5 cm in diameter and 2–5 cm in length) from a signle lithostratigraphic unit composed of non-to-moderately welded ash-flow tuff (a glass-rich pyroclastic rock partially fused by heat and pressure) with porosities ranging from 0.094 to 0.533 m 3 m -3 . Reproducibility of sample handling and testing procedures was demonstrated using replicate measurements. Precision and accuracy of load cell measurements were assessed using mass balance calculations and indicated agreement within a few tenths of a percent of total mass. Computed values of sorptivity, S , ranged from 8.83 × 10 -6 to 4.55 × 10 -4 m s -0.5 . The developed method should prove useful for measuring imbibition rates on a wide range of porous materials.

Soil Science Society of America Journal↗
USGS2010

The influence of nutrients and physical habitat in regulating algal biomass in agricultural streams

This study examined the relative influence of nutrients (nitrogen and phosphorus) and habitat on algal biomass in five agricultural regions of the United States. Sites were selected to capture a range of nutrient conditions, with 136 sites distributed over five study areas. Samples were collected in either 2003 or 2004, and analyzed for nutrients (nitrogen and phosphorous) and algal biomass (chlorophyll a ). Chlorophyll a was measured in three types of samples, fine-grained benthic material (CHL FG ), coarse-grained stable substrate as in rock or wood (CHL CG ), and water column (CHL S ). Stream and riparian habitat were characterized at each site. TP ranged from 0.004–2.69 mg/l and TN from 0.15–21.5 mg/l, with TN concentrations highest in Nebraska and Indiana streams and TP highest in Nebraska. Benthic algal biomass ranged from 0.47–615 mg/m 2 , with higher values generally associated with coarse-grained substrate. Seston chlorophyll ranged from 0.2–73.1 μg/l, with highest concentrations in Nebraska. Regression models were developed to predict algal biomass as a function of TP and/or TN. Seven models were statistically significant, six for TP and one for TN; r 2 values ranged from 0.03 to 0.44. No significant regression models could be developed for the two study areas in the Midwest. Model performance increased when stream habitat variables were incorporated, with 12 significant models and an increase in the r 2 values (0.16–0.54). Water temperature and percent riparian canopy cover were the most important physical variables in the models. While models that predict algal chlorophyll a as a function of nutrients can be useful, model strength is commonly low due to the overriding influence of stream habitat. Results from our study are presented in context of a nutrient-algal biomass conceptual model.

Environmental Management↗
USGS2022

Prospective and retrospective evaluation of the U.S. Geological Survey public aftershock forecast for the 2019-2021 Southwest Puerto Rico Earthquake and aftershocks

The M w "> M w 6.4 Southwest Puerto Rico Earthquake of 7 January 2020 was accompanied by a robust fore‐ and aftershock sequence. The U.S. Geological Survey (USGS) has issued regular aftershock forecasts for more than a year since the mainshock, available on a public webpage. Forecasts were accompanied by interpretive and informational material, published in English and Spanish. Informational products included narrative “scenarios” for how the aftershock sequence could play out, infographics, and a report on the potential duration of the aftershock sequence through the next decade. Forecasts are based on the epidemic‐type aftershock sequence (ETAS) model and generated using the USGS AftershockForecaster software—an interactive graphical user interface built on the OpenSHA platform ( Field et al. , 2003 ). The initial forecast is based on past sequences in similar tectonic environments; subsequent forecasts are tuned to the ongoing sequence via Bayesian model updating. Probabilistic aftershock forecasts for the next day, week, month, and year were publicly released and archived at a daily to monthly tempo, allowing for a truly prospective test of the forecast. Here, we evaluate the forecast over the first year of the recorded aftershocks. The ETAS‐based forecast performed well overall, successfully capturing both the chance of having at least one earthquake of a given magnitude in a forecast interval as well as the non‐Poissonian distribution of the total number of aftershocks within an interval. A retrospective analysis shows that the ETAS model is a substantial improvement over the existing Reasenberg and Jones (1989) forecast model. The exercise also reveals some limitations of the current model, in particular, with respect to nonstationarities in the aftershock magnitude distribution and model parameters throughout the evolving sequence.

Puerto Rico↗
USGS2009

In-Flight performance of MESSENGER's Mercury dual imaging system

The Mercury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, launched in August 2004 and planned for insertion into orbit around Mercury in 2011, has already completed two flybys of the innermost planet. The Mercury Dual Imaging System (MDIS) acquired nearly 2500 images from the first two flybys and viewed portions of Mercury's surface not viewed by Mariner 10 in 1974-1975. Mercury's proximity to the Sun and its slow rotation present challenges to the thermal design for a camera on an orbital mission around Mercury. In addition, strict limitations on spacecraft pointing and the highly elliptical orbit create challenges in attaining coverage at desired geometries and relatively uniform spatial resolution. The instrument designed to meet these challenges consists of dual imagers, a monochrome narrow-angle camera (NAC) with a 1.5?? field of view (FOV) and a multispectral wide-angle camera (WAC) with a 10.5?? FOV, co-aligned on a pivoting platform. The focal-plane electronics of each camera are identical and use a 1024??1024 charge-coupled device detector. The cameras are passively cooled but use diode heat pipes and phase-change-material thermal reservoirs to maintain the thermal configuration during the hot portions of the orbit. Here we present an overview of the instrument design and how the design meets its technical challenges. We also review results from the first two flybys, discuss the quality of MDIS data from the initial periods of data acquisition and how that compares with requirements, and summarize how in-flight tests are being used to improve the quality of the instrument calibration. ?? 2009 SPIE.

Conference Paper↗
USGS2016

Juvenile magma recognition and eruptive dynamics inferred from the analysis of ash time series: The 2015 reawakening of Cotopaxi volcano

Forecasting future activity and performing hazard assessments during the reactivation of volcanoes remain great challenges for the volcanological community. On August 14, 2015 Cotopaxi volcano erupted for the first time in 73 years after approximately four months of precursory activity, which included an increase in seismicity, gas emissions, and minor ground deformation. Here we discuss the use of near real-time petrological monitoring of ash samples as a complementary aid to geophysical monitoring, in order to infer eruption dynamics and evaluate possible future eruptive activity at Cotopaxi. Twenty ash samples were collected between August 14 and November 23, 2015 from a monitoring site on the west flank of the volcano. These samples contain a range of grain types that we classified as: hydrothermal/altered, lithic, juvenile, and free crystals. The relative proportions of theses grains evolved as the eruption progressed, with increasing amounts of juvenile material and a decrease in hydrothermally altered material. In samples from the initial explosion, juvenile grains are glassy, microlite-poor and contain hydrothermal minerals (opal and alunite). The rising magma came in contact with the hydrothermal system under confinement, causing hydro-magmatic explosions that cleared the upper part of the plumbing system. Subsequently, the magmatic column produced a thermal aureole in the conduit and dried out the hydrothermal system, allowing for dry eruptions. Magma ascent rates were low enough to allow for efficient outgassing and microlite growth. Constant supply of magma from below caused quasi-continuous disruption of the uppermost magma volume through a combination of shear-deformation and gas expansion. The combination of increasing crystallinity of juvenile grains, and high measured SO 2 flux indicate decreasing integrated magma ascent rates and clearing of the hydrothermal system along transport pathways in a system open to gas loss. The near real-time monitoring of ash samples combined with traditional geophysical monitoring techniques during the reawakening of Cotopaxi allowed us to gain a much clearer understanding of events than when using traditional geophysical monitoring alone.

Cotopaxi volcano↗
USGS2003

Evaluation of an expandable, breakaway radiocollar for white-tailed deer fawns

We evaluated an expandable, breakaway VHF radiocollar design for use on white-tailed deer (Odocoileus virginianus) from birth to about 1 year of age. A similar collar design has been used on caribou (Rangifer tarandus), but we found that the collar did not expand quickly enough to accommodate increase in neck circumference of fawns during the first 2 months of life. Consequently, we modified the stitching pattern so that the first expansion fold opened faster. We monitored performance of this modification on free-ranging and captive fawns. Also, we collected data on neck growth in fawns to document design requirements of expandable collars for white-tailed deer. Mean neck circumference at ???14 days of age of free-ranging fawns in Pennsylvania was 17.8 cm (SD=1.67, n=62) for males and 17.3 cm (SD=1.50, n=52) for females. Based on measurements of captive fawns, neck circumference increased 8.8 cm from birth to August, 2.5 cm from August to October, and 2.6 cm from October to March. Observations of captive fawns fitted with dummy radiocollars indicated that collars expanded when needed and caused no apparent discomfort to fawns. We detected no problems with use of 86 collars on 113 free-ranging fawns for >270 days and recovered radiocollars expanded as designed. The elastic collar material failed on 3 collars (3%) after 142, 207, and 226 days on fawns, and 1-5 radiocollars (???4%) were cast by fawns. Our modification to this radiocollar design reduced fawn discomfort or suffering, allowing researchers to better comply with principles of the Animal Welfare Act.

Wildlife Society Bulletin↗
USGS2015

Mineral potential for sediment-hosted copper deposits in the Islamic Republic of Mauritania (phase V, deliverable 75)

The presence of Neoproterozoic through Cambrian, continental, siliciclastic sedimentary rocks interbedded with dolomitic carbonates, shales, and glacial tillites similar to the Katanga Supergroup host rocks of the Central African Copperbelt and other sediment-hosted copper-bearing Proterozoic sequences worldwide, is first order criteria for consideration of the Neoproterozoic units of the Taoudeni Basin in Mauritania as prospective for sediment-hosted copper deposits. Review of the National Mineral Occurrences Database (Marsh and Anderson, 2015) and previous literature suggest that only a handful of small sediment-hosted copper occurrences have been found to date in Mauritania and that the resource potential for this deposit type is low. In the northern Taoudeni Basin, the most important occurrence is at Taradent. This occurrence consists of three mineralized horizons in the lower Neoproterozoic Char Group in three outcrop areas separated by alluvium over a strike length of 12 kilometers (km). The most extensively mineralized horizon consists of malachite and disseminated copper sulfides, and is concentrated at the base of a dolomitic interval, consistent with a reduced faciestype sediment-hosted copper deposit model. Additional and poorly described copper occurrences in the Taoudeni Basin margin sedimentary rocks in northeastern Mauritania, such as Chegga Guettatira and Sidi Bara, may be sediment-hosted copper occurrences and extend the potential throughout this portion of the Basin. Additional potential for sediment-hosted copper deposits is indicated in reports by the British Geological Survey (BGS; Gunn and others, 2004) and BRGM (Salpeteur, 2005) in the Neoproterozoic-Cambrian sedimentary rocks (Teniagouri Group) of the central and southern Taoudeni Basin at a number of occurrences in the vicinity of Fouges, Weringuel, and Gig Zig. These occurrences exhibit characteristics consistent with a reduced-facies-type sediment-hosted copper deposit model and based on correlation of similar host rocks extend the potential throughout the entire Taoudeni Basin margin. Very poorly described copper occurrences in the northeastern and southeastern part of the Basin at Kreb en Naga, Kreb en Naga SW, Berbere, Dhar Nema, Dhar Nema 2, Saile, and Nejam-Medroume all are described as occurring in sedimentary rocks and are hosted by or are in close proximity to voluminous outcrops of Jurassic microgabbros (also referred to as dolerite or diabase). Uncertainty exists as to whether they are sediment-hosted copper occurrences. They are likely more closely analogous to copper occurrences associated with mafic igneous activity. The determination of whether reported copper occurrences and associated sedimentary rocks at Kreb en Naga and Kreb en Naga SW in the northeastern Taoudeni Basin and the Dhar Nema occurrences in the southeastern Taoudeni are permissive of sediment-hosted copper mineralization was inconclusive due to the absence of copper showings. While sedimentary host rocks at these locations must be broadly considered permissive, the absence of other favorable geologic features in these areas indicates that the potential for mineral deposits of this type is low. The widespread presence of mafic sills and dikes of Jurassic age throughout these areas and descriptions of associated minor copper mineralization suggests that many of the copper occurrences in these areas are not of the sediment-hosted copper type. Highly speculative potential exists in the Coastal Basin for Revett-type copper deposits in unexposed Jurassic-Cretaceous sandstones that may contain structural traps with gas accumulations. Eocene continental red bed sandstones of the Gorgol Formation, where overlain by the shallow marine sedimentary rocks of the Rinndiao Formation, represent an additional low potential rock sequence within the southeastern portion of the Coastal Basin that is permissive of sediment-hosted copper deposits. Field examinations of outcrop areas in the vicinity of many of the known occurrences were performed in late 2007 to provide additional criteria for evaluating the potential for this type of mineralization in Mauritania. In general, the geographic coordinates of occurrences are imprecise and many of the occurrences could not be located. Examination of outcrops of the Char Group in the Taradent area confirms the permissive nature of these rocks for reduced-facies-type sediment-hosted copper deposits. Inspection of weak copper mineralization hosted by black shales at several occurrences in the Gadel-Maylime area confirms that these occurrences are also of the reduced-faciestype and that the black and green shales of the Bouly and Ould Yenje Formations are permissive. Reported copper analyses up to 0.75 percent copper at Taradent and a single analysis of mineralized shale in the Gadel-Maylime area containing 0.55 percent copper indicate that low grade ore material exists at these locations. However indications that such copper grades are continuous over significant intervals and present in large tonnages are lacking. Although mineral occurrence data and descriptive geological information are adequate to delineate areas favorable for sediment-hosted copper deposits, this review indicates that potential for this type of deposit in Mauritania is low.

Open-File Report↗
USGS2022

Remote sensing of visible dye concentrations during a tracer experiment on a large, turbid river

Understanding dispersion in rivers is critical for numerous applications, such as characterizing larval drift for endangered fish species and responding to spills of hazardous materials. Injecting a visible dye into the river can yield insight on dispersion processes, but conventional field instrumentation yields limited data on variations in dye concentration over time at a few, fixed points. Remote sensing can provide more detailed, spatially distributed information on the dye's motion, but this approach has only been tested in clear-flowing streams. The purpose of this study was to assess the potential of remote sensing to facilitate tracer studies in more turbid rivers. To pursue this objective, we injected Rhodamine WT dye into the Missouri River and collected field spectra from a boat, videos from a small unoccupied aircraft system (sUAS), and orthophotos from an airplane. Applying an optimal band ratio analysis (OBRA) algorithm to the field spectra revealed strong correlations ( R 2 = 0.936) between a spectrally based quantity and in situ concentration measurements. OBRA also performed well for broadband RGB (red, green, blue) images extracted from the sUAS-based videos; the resulting concentration maps were used to produce animations that captured movement of the dye pulse. Spectral mixture analysis of repeat orthophoto coverage yielded relative concentration estimates that provided a synoptic perspective on dispersion of the dye throughout the entire 13.8 km reach over the full 2.5-hr duration of the experiment. The results of this study demonstrate the potential to remotely sense tracer dye concentrations in large, highly turbid rivers.

Missouri↗
USGS1970

Methods and applications of electrical simulation in ground-water studies in the lower Arkansas and Verdigris River Valleys, Arkansas and Oklahoma

The Arkansas River Multiple-Purpose Plan will provide year-round navigation on the Arkansas River from near its mouth to Muskogee, Okla., and on the Verdigris River from Muskogee to Catoosa, Okla. The altered regimen in the Arkansas and Verdigris Rivers will affect ground-water conditions in the adjacent alluvial aquifers. In 1957 the U.S. Geological Survey and U.S. Army Corps of Engineers entered into a cooperative agreement for a comprehensive ground-water study of the lower Arkansas and Verdigris River valleys. At the request of the Corps of Engineers, the Geological Survey agreed to provide (1) basic ground-water data before, during, and after construction of the Multiple-Purpose Plan and (2) interpretation and projections of postconstruction ground-water conditions. The data collected were used by the Corps of Engineers in preliminary foundation and excavation estimates and by the Geological Survey as the basis for defining the hydrologic properties of, and the ground-water conditions in, the aquifer. The projections of postconstruction ground-water conditions were used by the Corps of Engineers in the planning, design, construction, and operation of the Multiple-Purpose Plan. Analysis and projections of ground-water conditions were made by use of electrical analog models. These models use the analogy between the flow of electricity in a resistance-capacitance circuit and the flow of a liquid in a porous and permeable medium. Verification provides a test of the validity of the analog to perform as the aquifer would, within the range of historic forces. The verification process consists of simulating the action of historic forces which have acted upon the aquifer and of duplicating the aquifer response with the analog. The areal distribution of accretion can be treated as an unknown and can be determined by analog simulation of the piezometric surface in an aquifer. Comparison of accretion with depth to piezometric surface below land surface shows that accretion decreases with decreasing depth to water level. The decrease in accretion is attributed mostly to the increase in evapotranspiration from the aquifer, and where water levels are very near the land surface, to the rejection of recharge. The maximum accretion and the decrease in accretion with the decrease in depth to water are dependent upon the climate and the thickness and lithology of the fine-grained material overlying the aquifer. Dams on the Arkansas and Verdigris Rivers will impose a direct change in water levels in the aquifers adjacent to the rivers. This change will be attenuated by the resultant change in accretion to the aquifer. The analogs of aquifers in the valleys were used to determine the change in ground-water level from preconstruction to postconstruction conditions.

Water Supply Paper↗
USGS1987

Synopsis of wetland functions and values: bottomland hardwoods with special emphasis on eastern Texas and Oklahoma

Bottomland hardwood wetlands are the natural cover type of many floodplain ecosystems in the southeastern United States. They are dynamic, productive systems that depend on intermittent flooding and moving water for maintenance of structure and function. Many of the diverse functions performed by bottomland hardwoods (e.g., flood control, sediment trapping, fish and wildlife habitat) are directly or indirectly valued by humans. Balanced decisions regarding bottomland hardwoods are often hindered by a limited ability to accurately specify the functions being performed by these systems and, furthermore, by an inability to evaluate these functions in economic terms. This report addresses these informational needs. It focuses on the bottomland hardwoods of eastern Texas and Oklahoma, serving as an introduction and entry to the literature. It is not intended to serve as a substitute for reference to the original literature. The first section of the report is a review of the major functions of bottomland hardwoods, grouped under the headings of hydrology, water quality, productivity, detritus, nutrients, and habitat. Although the hydrology of these areas is diverse and complex, especially with respect to groundwater, water storage at high flows can clearly function to attenuate peak flows, with possible reductions in downstream flooding damage. Water moving through a bottomland hardwood system carries with it various organic and inorganic constituents, including sediment, organic matter, nutrients, and pollutants. When waterborne materials are introduced to bottomland hardwoods (from river flooding or upland runoff), they may be retained, transformed, or transported. As a result, water quality may be significantly altered and improved. The fluctuating and flowing water regime of bottomland hardwoods is associated with generally high net primary productivity and rapid fluxes of organic matter and nutrients. These, in turn, support secondary productivity in the bottomland hardwoods and downstream through detrital export. A large number of studies detail the extensive utilization of bottomland hardwoods by animals. Several basic habitat components contribute to this support function, including: 1. Fluctuating water levels and permanent bodies of water, 2. Hard mast (e.g., acorns), 3. Dens and cavities, 4. High soil fertility, 5. Diversity of food and cover, 6. Predominance of woody plant communities, 7. Close proximity of diverse structural features, and 8. Linear features providing movement corridors. The second section of the report focuses on the bottomlands of eastern Texas and Oklahoma, including topics such as climate, soils, water resources, historical perspective, vegetation, and fauna. Considerable attention is given to structural characteristics in this section, in order to provide contrasts with bottomland hardwood ecosystems in other areas. In general, the bottomland hardwoods of eastern Texas and Oklahoma are very similar to those elsewhere in the southeastern United States. Differences include the occurrence and relative importance of some community types and plant species and the greater importance of reservoir construction as a source of bottomland hardwoods loss in eastern Texas and Oklahoma. Again, information on faunal utilization is extensive relative to the information available concerning other functions.

Oklahoma;Texas↗
USGS1999

Steady-state flow of solid CO2: Preliminary results

To help answer the question of how much solid CO 2 exists in the Martian south polar cap, we performed a series of laboratory triaxial deformation experiments at constant displacement rate in compression on jacketed cylinders of pure, polycrystalline CO 2 . Test conditions were temperatures 150 < T < 190 K, hydrostatic confining pressures 5≤ P ≤40 MPa, and strain rates 4.5×10 −8 ≤ ε ≤4.3×10 −4 s −1 . Most of the measurements follow a constitutive law of the form ε = Aσ n exp(−Q/RT), where σ is the applied differential stress, R is the gas constant, and the other constants have values as follows: A = 10 3 86 MPa −n s −1 , n = 5.6, and Q = 33 kJ/mol. Solid CO 2 is markedly weaker than water ice. Our results suggest that the south polar cap on Mars is unlikely to be predominately solid CO 2 , because the elevation and estimated age of the cap is difficult to reconcile with the very weak rheology of the material.

Geophysical Research Letters↗
USGS2008

Fischer-assays of oil-shale drill cores and rotary cuttings from the greater Green River basin, southwestern Wyoming

Chapter 1 of this CD–ROM is a database of digitized Fischer (shale-oil) assays of cores and cuttings from boreholes drilled in the Eocene Green River oil shale deposits in southwestern Wyoming. Assays of samples from some surface sections are also included. Most of the Fischer assay analyses were made by the former U.S. Bureau of Mines (USBM) at its laboratory in Laramie, Wyoming. Other assays, made by institutional or private laboratories, were donated to the U.S. Geological Survey (USGS) and are included in this database as well as Adobe PDF-scanned images of some of the original laboratory assay reports and lithologic logs prepared by USBM geologists. The size of this database is 75.2 megabytes and includes information on 971 core holes and rotary-drilled boreholes and numerous surface sections. Most of these data were released previously by the USBM and the USGS through the National Technical Information Service but are no longer available from that agency. Fischer assays for boreholes in northeastern Utah and northwestern Colorado have been published by the USGS. Additional data include geophysical logs, groundwater data, chemical and X-ray diffraction analyses, and other data. These materials are available for inspection in the office of the USGS Central Energy Resources Team in Lakewood, Colorado. The digitized assays were checked with the original laboratory reports, but some errors likely remain. Other information, such as locations and elevations of core holes and oil and gas tests, were not thoroughly checked. However, owing to the current interest in oil-shale development, it was considered in the public interest to make this preliminary database available at this time. Chapter 2 of this CD–ROM presents oil-yield histograms of samples of cores and cuttings from exploration drill holes in the Eocene Green River Formation in the Great Divide, Green River, and Washakie Basins of southwestern Wyoming. A database was compiled that includes about 47,000 Fischer assays from 186 core holes and 240 rotary drill holes. Most of the oil yield data are from analyses performed by the former U.S. Bureau of Mines oil shale laboratory in Laramie, Wyoming, with some analyses made by private laboratories. Location data for 971 Wyoming oil-shale drill holes are listed in a spreadsheet that is included in the CD–ROM. These Wyoming Fischer assays and histograms are part of a much larger collection of oil-shale information, including geophysical and lithologic logs, water data, chemical and X-ray diffraction analyses on the Green River oil-shale deposits in Colorado, Utah, and Wyoming held by the U.S. Geological Survey. Because of an increased interest in oil shale, this CD–ROM containing Fischer assay data and oil-yield histograms for the Green River oil-shale deposits in southwestern Wyoming is being released to the public. Microsoft Excel spreadsheets included with Chapter 2 contain the Fischer assay data from the 426 holes and data on the company name and drill-hole name, and location. Histograms of the oil yields obtained from the Fischer assays are presented in both Grapher and PDF format. Fischer assay text data files are also included in the CD–ROM.

Wyoming↗