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At least 937 records · Page 52Linked to original sources

A review of timing accuracy across the Global Seismographic Network

The accuracy of timing across a seismic network is important for locating earthquakes as well as studies that use phase‐arrival information (e.g., tomography). The Global Seismographic Network (GSN) was designed with the goal of having reported timing be better than 10 ms. In this work, we provide a brief overview of how timing is kept across the GSN and discuss how clock‐quality metrics are embedded in Standard for Exchange of Earthquake Data records. Specifically, blockette 1001 contains the timing‐quality field, which can be used to identify time periods when poor clock quality could compromise timing accuracy. To verify the timing across the GSN, we compare cross‐correlation lags between collocated sensors from 1 January 2000 to 1 January 2020. We find that the mean error is less than 10 ms, with much of the difference likely coming from the method or uncertainty in the phase response of the instruments. This indicates that timing across the GSN is potentially better than 10 ms. We conclude that unless clock quality is compromised (as indicated in blockette 1001), GSN data’s timing accuracy should be suitable for most current seismological applications that require 10 ms accuracy. To assist users, the GSN network operators have implemented a “gsn_timing” metric available via the Incorporated Research Institutions for Seismology Data Management Center that helps users identify data with substandard timing accuracy (the 10 ms design goal of the GSN).

Seismological Research Letters↗

Frontier areas and resource assessment: Case of the 1002 area of the Alaska North Slope

The U.S. Geological Survey's 1998 assessment of the 1002 Area of the Arctic National Wildlife Refuge significantly revised previous estimates of the area's petroleum supply potential. The mean (or expected) value of technically recoverable undiscovered oil for the Study Area (Federal 1002 Area, adjacent State waters, and Native Lands) is estimated at 10.4 billion barrels of oil (BBO) and for the Federal 1002 Area the mean is 7.7 BBO. Accumulation sizes containing the oil are expected to be sufficiently large to be of economic interest. At a market price of $21 per barrel, 6 BBO of oil in the Study area is expected to be economic. The Assessment's methodology, results, and the reasons for the significant change in assessments are reviewed. In the concluding section, policy issues raised by the assessment are discussed.

Alaska↗

Coluber (= Masticophis) flagellum piceus (Red Racer). Arboreal/nocturnal behavior

Many species of snakes display arboreal behavior and are often found in vegetation many meters above ground. Mojave Desert snake species rarely get very far above the ground surface and are perhaps limited by predominantly low growing vegetation. Coluber flagellum piceus is considered strictly diurnal and although may ascend vegetation while active, is thought to retreat to subterranean refugia at night. Werler and Dixon (2000. Texas Snakes: Identification, Distribution, and Natural History. University of Texas Press, Austin. 437 pp.) stated “The western coachwhip is active above ground only during daylight hours. It almost invariably retires to depths of an animal burrow before sundown, where it spends the night.” The normal morning activity period for C. flagellum appears to be from approximately 0700–1000 h from June through September (Jones and Whitford 1989. Southwest. Nat. 34:460–467). Secor and Nagy (1994. Ecology 75:1600–1614), and Secor (1995. Herpetol. Monogr. 9:169–186) determined that the average body temperature for active above ground activity of C. flagellum was (33.1°C + 0.1°C, range of 24.0°C–40.8°C, N = 502), stating that coachwhip snakes were seldom active on the surface with body temperatures below 28°C. Here, I report a C. f. piceus that apparently spent the night draped in a Creosote Bush ( Larrea tridentata ).

Nevada↗

Relationships of three species of bats impacted by white-nose syndrome to forest condition and management

Forest management activities can have substantial effects on forest structure and community composition and response of wildlife therein. Bats can be highly influenced by these structural changes, and understanding how forest management affects day-roost and foraging ecology of bats is currently a paramount conservation issue. With populations of many cave-hibernating bat species in eastern North America declining as a result of white-nose syndrome (WNS), it is increasingly critical to understand relationships among bats and forest-management activities. Herein, we provide a comprehensive literature review and synthesis of: (1) responses of northern long-eared ( Myotis septentrionalis ) and tri-colored ( Perimyotis subflavus ) bats—two species affected by WNS that use forests during summer—to forest management, and (2) an update to a previous review on the ecology of the endangered Indiana bat ( Myotis sodalis ).

General Technical Report↗

Recent advances in statistical methods for the estimation of sediment and nutrient transport in rivers

This paper reviews advances in methods for estimating fluvial transport of suspended sediment and nutrients. Research from the past four years, mostly dealing with estimating monthly and annual loads, is emphasized. However, because this topic has not appeared in previous IUGG reports, some research prior to 1990 is included. The motivation for studying sediment transport has shifted during the past few decades. In addition to its role in filling reservoirs and channels, sediment is increasingly recognized as an important part of fluvial ecosystems and estuarine wetlands. Many groups want information about sediment transport [ Bollman , 1992]: Scientists trying to understand benthic biology and catchment hydrology; citizens and policy-makers concerned about environmental impacts (e.g. impacts of logging [ Beschta , 1978] or snow-fences [ Sturges , 1992]); government regulators considering the effectiveness of programs to protect in-stream habitat and downstream waterbodies; and resource managers seeking to restore wetlands.

Reviews of Geophysics↗

Global stocks of selected mineral-based commodities

Introduction The U.S. Geological Survey, National Minerals Information Center, analyzes mineral and metal supply chains by identifying and describing major components of mineral and material flows from ore extraction, through intermediate forms, to a final product. This report focuses on an important component of the world’s supply chain: the amounts and global distribution of major consumer, producer, and exchange stocks of selected mineral commodities. In this report, the term “stock” is used instead of “inventory” and refers to accumulations of mined ore, intermediate products, and refined mineral-based commodities that are in a form that meets the agreed-upon specifications of a buyer or processor of intermediate products. These may include certain ores such as bauxite, concentrates, smelter products, and refined metals. Materials sometimes referred to as inventory for accounting purposes, such as ore contained in a deposit or in a leach pile, or materials that need to be further processed before they can be shipped to a consumer, are not considered. Stocks may be held (owned) by consumers, governments, investors, producers, and traders. They may serve as (1) a means to achieve economic, social, and strategic goals through government policies; (2) a secure source of supply to meet demand and to mitigate potential shortages in the supply chain; (3) a hedge to mitigate price volatility; and (4) vehicles for speculative investment. The paucity and uneven reliability of data for stocks of ores and concentrates and for material held by producers, consumers, and merchants hinder the accurate estimating of the size and distribution of this portion of the supply chain for certain commodities. This paper reviews the more visible stocks held in commodity exchange warehouses distributed throughout the world.

Scientific Investigations Report↗

Statistical methods in water resources

Preface This book began as class notes for a course we teach on applied statistical methods to hydrologists of the Water Resources Division, U. S. Geological Survey (USGS). It reflects our attempts to teach statistical methods which are appropriate for analysis of water resources data. As interest in this course has grown outside of the USGS, incentive grew to develop the material into a textbook. The topics covered are those we feel are of greatest usefulness to the practicing water resources scientist. Yet all topics can be directly applied to many other types of environmental data. This book is not a stand-alone text on statistics, or a text on statistical hydrology. For example, in addition to this material we use a textbook on introductory statistics in the USGS training course. As a consequence, discussions of topics such as probability theory required in a general statistics textbook will not be found here. Derivations of most equations are not presented. Important tables included in all general statistics texts, such as quantiles of the normal distribution, are not found here. Neither are details of how statistical distributions should be fitted to flood data -- these are adequately covered in numerous books on statistical hydrology. We have instead chosen to emphasize topics not always found in introductory statistics textbooks, and often not adequately covered in statistical textbooks for scientists and engineers. Tables included here, for example, are those found more often in books on nonparametric statistics than in books likely to have been used in college courses for engineers. This book points the environmental and water resources scientist to robust and nonparametric statistics, and to exploratory data analysis. We believe that the characteristics of environmental (and perhaps most other 'real') data drive analysis methods towards use of robust and nonparametric methods. Exercises are included at the end of chapters. In our course, students compute each type of analysis (t-test, regression, etc.) the first time by hand. We choose the smaller, simpler examples for hand computation. In this way the mechanics of the process are fully understood, and computer software is seen as less mysterious. We wish to acknowledge and thank several other scientists at the U. S. Geological Survey for contributing ideas to this book. In particular, we thank those who have served as the other instructors at the USGS training course. Ed Gilroy has critiqued and improved much of the material found in this book. Tim Cohn has contributed in several areas, particularly to the sections on bias correction in regression, and methods for data below the reporting limit. Richard Alexander has added to the trend analysis chapter, and Charles Crawford has contributed ideas for regression and ANOVA. Their work has undoubtedly made its way into this book without adequate recognition. Professor Ken Potter (University of Wisconsin) and Dr. Gary Tasker (USGS) reviewed the manuscript, spending long hours with no reward except the knowledge that they have improved the work of others. For that we are very grateful. We also thank Madeline Sabin, who carefully typed original drafts of the class notes on which the book is based. As always, the responsibility for all errors and slanted thinking are ours alone.

Techniques of Water-Resources Investigations↗

Monitoring recreation on federally managed lands and waters—Aspects of visitor use

Federally managed public lands and waters receive about 1 billion recreational visits each year. Data on these visitors can aid in guiding policy decisions, managing resources effectively, and communicating the economic contributions of lands and waters. This report explores the methods used by agencies to collect data on aspects of recreational visitor use to Federal lands and waters (apart from visitation numbers, which are the focus of a companion publication). Aspects of recreational visitor use include visitor demographics, recreational activity participation, visitor satisfaction, visitor attitudes and experiences, trip characteristics, and economic contributions. We review practices used to understand aspects of visitor use across seven Federal agencies, revealing similarities such as the use of visitor intercept surveys and coverage of similar topic area, and differences in how survey programs are operationalized and how specific questions on visitor surveys are worded. We also evaluate emerging technologies, such as geolocated social media and mobile device location data, for their potential to aid in understanding aspects of visitor use. This report concludes with potential opportunities to enhance data collection and coordination, ensuring cost-effective data collection and informed decision-making.

SocArXiv↗

Monitoring recreation on federally managed lands and waters—Aspects of visitor use

Federally managed public lands and waters receive around 1 billion recreational visits each year. Data on these visitors can aid in guiding policy decisions, managing resources effectively, and communicating the economic contributions of lands and waters. This report explores the methods used by agencies to collect data on aspects of recreational visitor use to Federal lands and waters (apart from visitation numbers, which are the focus of a companion publication). Aspects of recreational visitor use include visitor demographics, recreational activity participation, visitor satisfaction, visitor attitudes and experiences, trip characteristics, and economic contributions. We review practices used to understand aspects of visitor use across seven Federal agencies, revealing similarities such as the use of visitor intercept surveys and coverage of similar topic areas, and differences in how survey programs are operationalized and how specific questions on visitor surveys are worded. We also evaluate emerging technologies, such as geolocated social media and mobile device location data, for their potential to aid in understanding aspects of visitor use. This report concludes with potential opportunities to enhance data collection and coordination, ensuring cost-effective data collection and informed decision making.

Scientific Investigations Report↗

Updated study reporting levels (SRLs) for trace-element data collected for the California Groundwater Ambient Monitoring and Assessment (GAMA) Priority Basin Project, October 2009-March 2013

Groundwater samples have been collected in California as part of statewide investigations of groundwater quality conducted by the U.S. Geological Survey for the Groundwater Ambient Monitoring and Assessment (GAMA) Priority Basin Project (PBP). The GAMA-PBP is being conducted in cooperation with the California State Water Resources Control Board to assess and monitor the quality of groundwater resources used for drinking-water supply and to improve public knowledge of groundwater quality in California. Quality-control samples (source-solution blanks, equipment blanks, and field blanks) were collected in order to ensure the quality of the groundwater sample results. Olsen and others (2010) previously determined study reporting levels (SRLs) for trace-element results based primarily on field blanks collected in California from May 2004 through January 2008. SRLs are raised reporting levels used to reduce the likelihood of reporting false detections attributable to contamination bias. The purpose of this report is to identify any changes in the frequency and concentrations of detections in field blanks since the last evaluation and update the SRLs for more recent data accordingly. Constituents analyzed were aluminum (Al), antimony (Sb), arsenic (As), barium (Ba), beryllium (Be), boron (B), cadmium (Cd), chromium (Cr), cobalt (Co), copper (Cu), iron (Fe), lead (Pb), lithium (Li), manganese (Mn), molybdenum (Mo), nickel (Ni), selenium (Se), silver (Ag), strontium (Sr), thallium (Tl), tungsten (W), uranium (U), vanadium (V), and zinc (Zn). Data from 179 field blanks and equipment blanks collected from March 2006 through March 2013 by the GAMA-PBP indicated that for trace elements that had a change in detection frequency and concentration since the previous review, the shift occurred near October 2009, in conjunction with a change in the capsule filters used by the study. Results for 89 field blanks and equipment blanks collected from October 2009 through March 2013 were evaluated for potential contamination bias by using the same approach developed by Olsen and others (2010). Some data collected by the National Water-Quality Assessment (NAWQA) Program for the Southern California Coastal Drainages study unit were included to supplement the GAMA-PBP data. The detection frequency and upper threshold of potential contamination bias (BD-90/90) were determined from field-blank and equipment-blank data for each trace element. The BD-90/90 is the 90th percentile concentration of potential extrinsic contamination calculated by using the binomial probability distribution for greater than 90 percent confidence. Additionally, data from laboratory blanks and blind blanks analyzed by the National Water Quality Laboratory (NWQL) during water years 2010 through 2013, and compiled by the USGS Branch of Quality Systems (BQS), were considered for each trace element. These results were compared to each constituent’s reporting level to determine whether an SRL was necessary to minimize the potential for detections in the groundwater samples, attributed principally to contamination bias. Results of the evaluation were used to set SRLs for trace-element data for about 1,135 samples of groundwater collected by the GAMA-PBP between October 2009 and March 2013. Ten trace elements analyzed (Sb, As, Be, B, Cd, Li, Se, Ag, Tl, and U) had blank results that did not necessitate establishing SRLs during this review or the review by Olsen and others (2010). Five trace elements analyzed (Al, Ba, Cr, Sr, and V) had blank results that necessitated establishing an SRL during the previous review but did not need an SRL starting October 2009. One trace element (Fe) had field and laboratory-blank results that necessitated keeping the previous SRL (6 micrograms per liter [μg/L]). Two trace elements (Ni and W) had quality-control results that warranted decreasing the previous SRL, and five trace elements (Cu, Pb, Mn, Mo, and Zn) had field, laboratory, or blind blank results that warranted establishing an SRL for the first time or increasing the previous SRL. SRLs for Cu (2.1 μg/L), Pb (0.82 μg/L), Mn (0.66 μg/L), Mo (0.023 μg/L), Ni (0.21 μg/L), W (0.023 μg/L), and Zn (6.2 μg/L) were changed to these levels starting October 2009, based on the BD-90/90 concentration for field blanks or the 99th percentile concentration for laboratory or blind blanks. The SRL for Fe was maintained at 6 μg/L, based on the minimum laboratory reporting level for iron. SRLs for these eight constituents were at least an order of magnitude below the regulatory benchmarks established for drinking water for health and aesthetic purposes; therefore, the practice of reporting concentrations below the SRLs as less than or equal to (≤) the measured value would not prevent the identification of values greater than the drinking-water benchmarks. Co was detected in 99 percent of field blanks, and with a BD-90/90 concentration of 0.38 μg/L, all groundwater results starting October 2009 were coded as “reviewed and rejected.” Co does not currently have a regulatory benchmark for drinking water. The primary sources of contamination for trace elements inferred from this review are the equipment or processes used in the field to collect the samples or in the laboratory. In particular, contamination in field blanks of Co and Mn was attributed to the high-capacity 0.45-micrometer pore-size capsule filters that were in regular use beginning in October 2009 by several USGS programs, including the GAMA-PBP and NAWQA Program, for filtering samples for analysis of trace elements. The SRLs determined in this report are intended to be used for GAMA groundwater-quality data for samples collected October 2009 through March 2013, or for as long as quality-control data indicate contamination similar to what was observed in this report; quality-control data should be continuously reviewed and SRLs re-assessed on at least a study-unit basis.

California↗

Progress report on the Killigwa anticlinorium, 1953

This report was prepared to assist in the planning of seismic profiles to be run across the anticlinorium in the vicinity of the Kiligwa River. The stratigraphy and structure of the mapped area south of the anticlinorium are reviewed. Two facies of the Lisburne formation, a calcarenite-hydroclastic limestone facies and a black shale, black chert and dark limestone facies, have been distinguished. In the southern foothills, the black shale facies appears to have been thrust from the south over the limestone facies. The available evidence indicates that the Lisburne formation, as limestone or a more proximal facies was doposited over the area of the anticlinorium. Following a redefinition of the Torok formation in the type area, strata formerly mapped as Torok have here been designated Castle Mountain formation. The depositional history of the Castle Mountain formation reflects active orogeny. Lenses of coarse clastics appear to have been dumped in local basins; equivalent beds to the north are much finer. A basal zone of sandstone may be more extensive and may correlate with the sandstones noted along and north of the anticlinorium.

Alaska↗

Diagnostic methodology is critical for accurately determining the prevalence of ichthyophonus infections in wild fish populations

Several different techniques have been employed to detect and identify Ichthyophonus spp. in infected fish hosts; these include macroscopic observation, microscopic examination of tissue squashes, histological evaluation, in vitro culture, and molecular techniques. Examination of the peer-reviewed literature revealed that when more than 1 diagnostic method is used, they often result in significantly different results; for example, when in vitro culture was used to identify infected trout in an experimentally exposed population, 98.7% of infected trout were detected, but when standard histology was used to confirm known infected tissues from wild salmon, it detected ~50% of low-intensity infections and ~85% of high-intensity infections. Other studies on different species reported similar differences. When we examined a possible mechanism to explain the disparity between different diagnostic techniques, we observed non-random distribution of the parasite in 3-dimensionally visualized tissue sections from infected hosts, thus providing a possible explanation for the different sensitivities of commonly used diagnostic techniques. Based on experimental evidence and a review of the peer-reviewed literature, we have concluded that in vitro culture is currently the most accurate diagnostic technique for determining infection prevalence of Ichthyophonus, particularly when the exposure history of the population is not known.

Journal of Parasitology↗

An annotated bibliography for lamprey habitat in the White Salmon River, Washington

The October 2011 decommissioning of Condit Dam on the White Salmon River at river kilometer (rkm) 5.3 removed a significant fish passage barrier from the White Salmon River basin for the first time in nearly a century. This affords an opportunity to regain a potentially important drainage basin for Pacific lamprey ( Entosphenus tridentatus ) production. In anticipation of Pacific lamprey recolonization or reintroduction, aquatic resource managers, such as the Yakama Nation (YN), are planning to perform surveys in the White Salmon River and its tributaries. The likely survey objectives will be to investigate the presence of lamprey, habitat conditions, and habitat availability. In preparation for this work, a compilation and review of the relevant aquatic habitat and biological information on the White Salmon River was conducted. References specific to the White Salmon River were collected and an annotated bibliography was produced including reports containing: •Spatial information about where various habitat surveys or monitoring have occurred over the past 20 years; •Database information relevant to habitat attributes (for example, pools, riffles, or glides); •Riparian surveys along major tributary streams; •Water temperature and sediment information; •Lamprey surveys, observations, and collections; •Spawning gravel surveys; and •Surveys that inventory habitat degradation or other environmental factors that may limit potential future productivity of lamprey.

Washington↗

Geographic Variation in Hirundo pyrrhonota (Cliff Swallow) from Northern North America

The number of subspecies recognized in Hirundo pyrrhonota Vieillot (Cliff Swallow) from Alaska, Canada, and the northern contiguous United States ranges from one (Peters 1960) to three (e.g., Jewett et al. 1953, Oberholser, 1920, breeding from central Alaska to the central Great Basin, and two disjunct populations of nominate pyrrhonota , breeding on the west coast and east of the Rocky Mountains. Although various authors have reported measurements of wing chord, they have not provided quantitative data for other plumage characters, and they disagree in the characterizations and ranges of the subspecies they recognize. Because of this, I reviewed the geographic variation among the northern populations. My study is confined to specimens from Alaska, Canada, and the contigeous United States south to Merced County in California, both slopes of the Rocky Mountains from Montana and Colorado, and northern half of the eastern United States from Kansas east to Virginia (Figure 1). The A.O.U. (1957) gave the breeding range of hypopolia as extending from Alaska and Mackenzie to southeastern British Columbia, the eastern parts of Washington, Oregon, and central-eastern California, central Nevada, northern Utah, Montana, and northwestern Wyoming, and the range of nominate pyrhonota as from southwestern British Columbia, western Oregon and Washington to southern California, southern Nevada, southern and eastern Utag, and east of the Rocky Mountains. I excluded specimens of H. p. ganieri Phillips, 1986, a subspecies (Browning 1990) that breeds from at least west-central Tennessee to Texas, and H. p. tachina Oberholser, 1903 (sensu Phillips 1986), which breeds north to central California, Utah, Arizona, and new Mexico. I follow Phillips (1973) for the use of the generic name Hirundo for the Cliff Swallow, Hellmayr (1935) for the use of the specific name pyrrhonota .

Western Birds↗

Gas bubble disease: mortalities of coho salmon, Oncorhynchus kisutch, in water with constant total gas pressure and different oxygen-nitrogen ratios

A review of the literature regarding gas-bubble disease can be found in a recent publication by Rucker (1972); one by the National Academy of Science (Anonymous in press); and an unpublished report by Weitkamp and Katz (1973)." Most discussions on gas-bubble disease have dealt with the inert gas, nitrogen-oxygen was given a secondary role. It is important to know the relationship of nitrogen and oxygen when we are concerned with the total gas pressure in water. Where water becomes aerated at dams or falls, oxygen and nitrogen are usually about equally saturated, however, many of the samples analyzed from the Columbia River indicate that nitrogen is often about 7% higher than oxygen when expressed as a percentage. When oxygen is removed from water by metabolic and chemical action, or when oxygen is added to the water by photosynthesis, there is a definite change in the ratio of oxygen and the inert gases (mainly nitrogen with some argon, etc.). This present study shows the effect of varying the oxygen and nitrogen ratio in water on fingerling coho salmon, Oncorh.llnchllS kislltch, while maintaining a constant total gas pressure. The primary purpose of these experiments was to determine differences in lethality of various gas ratios of oxygen and nitrogen at a constant total gas pressure of 119%. I also wished to determine whether there was a difference in susceptibility between sizes and stocks of juvenile coho. Also to be examined was the effect of reducing the oJl:ygen while holding the nitrogen constant.

Fishery Bulletin↗

Global nonfuel mineral exploration trends 2001-2015

This review summarizes significant exploration trends related to active sites and budgets, mineral commodities and regional factors for the years 2001-2015. Data were compiled by specialists in the USGS-NMIC, and reported annually in the USGS-NMIC Minerals Yearbook series and in the May issue of Mining Engineering magazine. External data for these analyses were derived from industry sources, published literature, and SNL Metals & Mining, an offering of S&P Global Market Intelligence (New York, NY).

Mining Engineering↗