SEARCH · Search USGS

Results for “Detailed procedure”

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

SourceResearch connectionFrom yearThrough year

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

At least 163 records · Page 9Linked to original sources

USGS2016

Assessing potential scour using the South Carolina bridge-scour envelope curves

Summary Bridge-scour equations presented in the Federal Highway Administration Hydraulic Engineering Circular No. 18 reflect the current state-of-the practice for predicting scour at bridges. Although these laboratory-derived equations provide an important resource for assessing scour potential, there is a measure of uncertainty when applying these equations to field conditions. The uncertainty and limitations have been acknowledged by laboratory researchers and confirmed in field investigations. Because of the uncertainty associated with bridge-scour equations, HEC-18 recommends that engineers evaluate the computed scour depths obtained from the equations and modify the resulting data if they appear unreasonable. Perhaps the best way to evaluate the reasonableness of predicted scour is to compare it to field measurements of historic scour. Historic field data show scour depths resulting from high flows and provide a reference for evaluating predicted scour. It is rare, however, that such data are available at or near a site of interest, making the evaluation of predicted scour as compared to field data difficult if not impossible. Realizing the value of historic scour measurements, the U.S. Geological Survey (USGS), in cooperation with the South Carolina Department of Transportation (SCDOT), conducted a series of three field investigations to collect historic scour data with the goal of understanding regional trends of scour at riverine bridges in South Carolina. Historic scour measurements, including measurements of clear-water abutment, contraction, and pier scour, as well as live-bed contraction and pier scour, were made at more than 200 bridges. These field investigations provided valuable insights into regional scour trends and yielded regional bridge-scour envelope curves that can be used as supplementary tools for assessing all components of scour at riverine bridges in South Carolina. The application and limitations of these envelope curves were documented in four reports. Because each report addresses different components of bridge scour, it was recognized that there was a need to develop an integrated procedure for applying the envelope curves to help assess scour potential at riverine bridges in South Carolina. The result of that effort is detailed in Benedict and others (2016) and summarized in this fact sheet.

South Carolina↗

USGS1988

Methods for delineating flood-prone areas in the Great Basin of Nevada and adjacent states

The Great Basin is a region of about 210,000 square miles having no surface drainage to the ocean; it includes most of Nevada and parts of Utah, California, Oregon, Idaho, and Wyoming. The area is characterized by many parallel mountain ranges and valleys trending north-south. Stream channels usually are well defined and steep within the mountains, but on reaching the alluvial fan at the canyon mouth, they may diverge into numerous distributary channels, be discontinuous near the apex of the fan, or be deeply entrenched in the alluvial deposits. Larger rivers normally have well-defined channels to or across the valley floors, but all terminate at lakes or playas. Major floods occur in most parts of the Great Basin and result from snowmelt, frontal-storm rainfall, and localized convective rainfall. Snowmelt floods typically occur during April-June. Floods resulting from frontal rain and frontal rain on snow generally occur during November-March. Floods resulting from convective-type rainfall during localized thunderstorms occur most commonly during the summer months. Methods for delineating flood-prone areas are grouped into five general categories: Detailed, historical, analytical, physiographic, and reconnaissance. The detailed and historical methods are comprehensive methods; the analytical and physiographic are intermediate; and the reconnaissance method is only approximate. Other than the reconnaissance method, each method requires determination of a T-year discharge (the peak rate of flow during a flood with long-term average recurrence interval of T years) and T-year profile and the development of a flood-boundary map. The procedure is different, however, for each method. Appraisal of the applicability of each method included consideration of its technical soundness, limitations and uncertainties, ease of use, and costs in time and money. Of the five methods, the detailed method is probably the most accurate, though most expensive. It is applicable to hydraulic and topographic conditions found in many parts of the Great Basin. The historical method is also applicable over a wide range of conditions and is less expensive than the detailed method. However, it requires more historical flood data than are usually available, and experience and judgement are needed to obtain meaningful results. The analytical method is also less expensive than the detailed method and can be used over a wide range of conditions in which the T-year discharge can be determined directly. Experience, good judgement, and thorough knowledge of hydraulic principles are required to obtain adequate results, and the method has limited application in other than rigid-channel situations. The physiographic method is applicable to rigid-boundary channels and is less accurate than the detailed method. The reconnaissance method is relatively imprecise, but it may be the most rational method to use on alluvial fans or valley floors with discontinuous channels. In general, a comprehensive method is most suitable for use with rigid-bank streams in urban areas; only an approximate method seems justified in undeveloped areas.

Water Supply Paper↗

USGS1995

Scour measurements at bridge sites during 1993 Upper Mississippi River Basin flood

The record flood on the upper Mississippi River basin during the summer of 1993 provided a rare opportunity for collection of data on streambed scour at bridges and for testing of scour data collection equipment under extreme hydraulic conditions. Real-time scour measurements at bridges are categorized into one of three classes according to their objective: inspection measurements, limited-detail measurements, and detailed measurements. All three types of measurements were made during the 1993 flood. Recent advances in technology and improved application of existing technology allow hydraulic and channel bathymetry data to be collected more accurately, in greater detail, and more efficiently than previously possible. Two limited-detail and two detailed data sets are presented. The observed depths of scour are consistently less than the depths of pier scour estimated by use of recommended procedures. Additional data processing, analysis, and visualization are required to characterize and understand complex processes measured by use of state-of-the-art instrumentation.

Upper Mississippi River basin↗

USGS2002

Steady shape analysis of tomographic pumping tests for characterization of aquifer heterogeneities

Hydraulic tomography, a procedure involving the performance of a suite of pumping tests in a tomographic format, provides information about variations in hydraulic conductivity at a level of detail not obtainable with traditional well tests. However, analysis of transient data from such a suite of pumping tests represents a substantial computational burden. Although steady state responses can be analyzed to reduce this computational burden significantly, the time required to reach steady state will often be too long for practical applications of the tomography concept. In addition, uncertainty regarding the mechanisms driving the system to steady state can propagate to adversely impact the resulting hydraulic conductivity estimates. These disadvantages of a steady state analysis can be overcome by exploiting the simplifications possible under the steady shape flow regime. At steady shape conditions, drawdown varies with time but the hydraulic gradient does not. Thus transient data can be analyzed with the computational efficiency of a steady state model. In this study, we demonstrate the value of the steady shape concept for inversion of hydraulic tomography data and investigate its robustness with respect to improperly specified boundary conditions.

Water Resources Research↗

USGS1969

Measurement of discharge by the moving-boat method

This chapter describes the procedures for measuring discharge in large streams by the moving-boat technique. During the traverse of a boat across a stream, a sonic sounder records the geometry of the cross section, and a continuously operating current meter senses the combined stream and boat velocities. These data are converted to discharge for the cross section quickly, efficiently, and inexpensively. Measurements obtained by the moving-boat technique compare within 5 percent of measurements obtained by conventional means. Field and office procedures applicable to this method are outlined. Theory of technique is developed and equipment required is described. Selection and preparation of the cross section is detailed. A complete facsimile example of computation of a moving-boat measurement is given, and the determination and application of adjustment factors are described.

Techniques of Water-Resources Investigations↗

USGS1975

Bacterial diseases of fishes: Diagnostic procedures for gram-negative pathogens

A diagnostic scheme employing 10 media, 4 reagents, and 5 specific antiserums has been devised for identification of gram-negative pathogens of fishes. The scheme is not intended for detailed speciation of organisms, but for generic identification of organisms associated with infected fishes. Diagnosis can be accomplished in 24 h with selective media and antiserums, and in no more than 72 h with other media and reagents.

Journal of the Fisheries Research Board of Canada↗

USGS1978

Digital model of ground-water flow in the Piceance Basin, Rio Blanco and Garfield Counties, Colorado

The digital model used to simulate ground-water flow in the aquifer system in the basin drained by Piceance and Yellow Creeks in northwestern Colorado is described in detail. The model is quasi three-dimensional in that it simulates ground-water flow in a multiaquifer system by assuming horizontal flow in the aquifers and vertical flow through the confining layers separating the aquifers. The model uses the iterative alternating-direction implicit procedure to solve the finite-difference flow equations. The digital model is documented by a program listing and flow charts. Data used in the model and sample output are presented to document the simulation of steady-state flow in the aquifer system. The variables used in the computer program and program options are discussed in detail. (Woodard-USGS)

Water-Resources Investigations Report↗

USGS1991

Quasi-static fault growth and shear fracture energy in granite

The failure process in a brittle granite sample can be stabilized by controlling axial stress to maintain a constant rate of acoustic emission. As a result, the post-failure stress curve can be followed quasistatically, extending to hours the fault growth process which normally would occur violently in a fraction of a second. Using a procedure originally developed to locate earthquakes, acoustic emission arrival-time data are inverted to obtain three-dimensional locations of microseisms. These locations provide a detailed view of fracture nucleation and growth.

Nature↗

USGS2014

Validation of the SCEC broadband platform V14.3 simulation methods using pseudo spectral acceleration data

This paper summarizes the evaluation of ground motion simulation methods implemented on the SCEC Broadband Platform (BBP), version 14.3 (as of March 2014). A seven-member panel, the authorship of this article, was formed to evaluate those methods for the prediction of pseudo-‐spectral accelerations (PSAs) of ground motion. The panel’s mandate was to evaluate the methods using tools developed through the validation exercise (Goulet et al. ,2014), and to define validation metrics for the assessment of the methods’ performance. This paper summarizes the evaluation process and conclusions from the panel. The five broadband, finite-source simulation methods on the BBP include two deterministic approaches herein referred to as CSM (Anderson, 2014) and UCSB (Crempien and Archuleta, 2014); a band-‐limited stochastic white noise method called EXSIM (Atkinson and Assatourians, 2014); and two hybrid approaches, referred to as G&P (Graves and Pitarka, 2014) and SDSU (Olsen and Takedatsu, 2014), which utilize a deterministic Green’s function approach for periods longer than 1 second and stochastic methods for periods shorter than 1 second. Two acceptance tests were defined to validate the broadband finite‐source ground methods (Goulet et al., 2014). Part A compared observed and simulated PSAs for periods from 0.01 to 10 seconds for 12 moderate to large earthquakes located in California, Japan, and the eastern US. Part B compared the median simulated PSAs to published NGA-‐West1 (Abrahamson and Silva, 2008; Boore and Atkinson, 2008; Campbell and Bozorgnia, 2008; and Chiou and Youngs, 2008) ground motion prediction equations (GMPEs) for specific magnitude and distance cases using a pass-‐fail criteria based on a defined acceptable range around the spectral shape of the GMPEs. For the initial Part A and Part B validation exercises during the summer of 2013, the software for the five methods was locked in at version 13.6 (see Maechling et al., 2014). In the spring of 2014, additional moderate events were considered for the Part A validation, and additional magnitude and distance cases were considered for the Part B validation, for the software locked in at version 14.3. Several of the simulation procedures, specifically UCSB and SDSU, changed significantly between versions 13.6 and 14.3. The CSM code was not submitted in time for the v14.3 evaluation and its detailed performance is not addressed in this paper. As described in Goulet et al. (2014) and Maechling et al. (2014), the BBP generates a variety of products, including three-‐component acceleration time series. A series of post-‐processing codes were developed to provide individual component PSAs and average median horizontal-‐component PSA (referred to as RotD50; Boore, 2010) for oscillator periods ranging from 0.01 to 10 seconds, as well as median PSA values computed using the NGA-‐West 1 GMPEs. The BBP was also configured to provide statistical analysis of simulation results relative to recordings (Part A) and GMPEs (Part B) as described further in sections below. As part of our evaluation, we reviewed documentation provided by each of the developers, which included the technical basis behind the methods and the developer’s self-‐assessments regarding the extrapolation capabilities (in terms of magnitude and distance ranges) of their methods. Two workshops were held in which methods and results were presented, and the panel was given the opportunity to question the developers and to have detailed technical discussions. A SCEC report (Dreger et al., 2013) describes the results of this review for BBP version 13.6. This paper summarizes that work and presents results for the more recent BBP 14.3 validation.

Seismological Research Letters↗

USGS1999

Successful aquatic animal disease emergency programmes

The authors provide examples of emergency programmes which have been successful in eradicating or controlling certain diseases of aquatic animals. The paper is divided into four parts. The first part describes the initial isolation of viral haemorrhagic septicaemia (VHS) virus in North America in the autumn of 1988 from feral adult chinook ( Oncorhynchus tshawytscha ) and coho salmon ( O.kisutch ) returning for spawning. The fish disease control policies at both State and Federal levels in the United States of America required quarantine and emergency eradication measures upon the finding of certain exotic fish pathogens, including VHS virus. The procedures for emergency plans, destruction of stocks and disinfection of facilities are described, as well as challenge experiments with the North American strains of VHS virus and the detection of the virus in marine fish species (cod [ Gadus macrocephalus ] and herring [ Clupea harengus pallasi ]) in the Pacific Ocean. The second part of the paper outlines the aquatic animal legislation in Great Britain and within the European Union, in regard to contingency plans, initial investigations, action on the suspicion of notifiable disease and action on confirmation of infection. The legal description is followed by an account of an outbreak of viral haemorrhagic septicaemia in turbot (Scophthalmus maximus) in Great Britain, including the stamping-out process at the affected farm and investigations conducted to screen other farms in the vicinity for possible infection. The third part provides a historical review of the build-up of infectious salmon anaemia (ISA) in Norway and the attempts to control the disease using legal measures in the absence of detailed knowledge of the aetiology, epizootiology, pathogenesis, etc. of the disease. The measures taken show that the spread of ISA can be controlled using restrictions on the movement of fish, disinfection procedures, etc. However, acceptance and understanding of the chosen strategy by the fish farmers is a pre-requisite to reach that goal. Finally, the paper summarises future needs for national and international legislation, including the development of standard approaches for control, the creation of appropriate infrastructures and a better understanding of the epidemiology of aquatic animal diseases.

Revue Scientifique et Technique↗

USGS2016

Using structural equation modeling to link human activities to wetland ecological integrity

The integrity of wetlands is of global concern. A common approach to evaluating ecological integrity involves bioassessment procedures that quantify the degree to which communities deviate from historical norms. While helpful, bioassessment provides little information about how altered conditions connect to community response. More detailed information is needed for conservation and restoration. We have illustrated an approach to addressing this challenge using structural equation modeling (SEM) and long-term monitoring data from Rocky Mountain National Park (RMNP). Wetlands in RMNP are threatened by a complex history of anthropogenic disturbance including direct alteration of hydrologic regimes; elimination of elk, wolves, and grizzly bears; reintroduction of elk (absent their primary predators); and the extirpation of beaver. More recently, nonnative moose were introduced to the region and have expanded into the park. Bioassessment suggests that up to half of the park's wetlands are not in reference condition. We developed and evaluated a general hypothesis about how human alterations influence wetland integrity and then develop a specific model using RMNP wetlands. Bioassessment revealed three bioindicators that appear to be highly sensitive to human disturbance (HD): (1) conservatism, (2) degree of invasion, and (3) cover of native forbs. SEM analyses suggest several ways human activities have impacted wetland integrity and the landscape of RMNP. First, degradation is highest where the combined effects of all types of direct HD have been the greatest (i.e., there is a general, overall effect). Second, specific HDs appear to create a “mixed-bag” of complex indirect effects, including reduced invasion and increased conservatism, but also reduced native forb cover. Some of these effects are associated with alterations to hydrologic regimes, while others are associated with altered shrub production. Third, landscape features created by historical beaver activity continue to influence wetland integrity years after beavers have abandoned sites via persistent landforms and reduced biomass of tall shrubs. Our model provides a system-level perspective on wetland integrity and provides a context for future evaluations and investigations. It also suggests scientifically supported natural resource management strategies that can assist in the National Park Service mission of maintaining or, when indicated, restoring ecological integrity “unimpaired for future generations.”

Colorado↗

USGS2015

Collections management plan for the U.S. Geological Survey Woods Hole Coastal and Marine Science Center Data Library

The U.S. Geological Survey Woods Hole Coastal and Marine Science Center has created a Data Library to organize, preserve, and make available the field, laboratory, and modeling data collected and processed by Woods Hole Coastal and Marine Science Center staff. This Data Library supports current research efforts by providing unique, historic datasets with accompanying metadata. The Woods Hole Coastal and Marine Science Center’s Data Library has custody of historic data and records that are still useful for research, and assists with preservation and distribution of marine science records and data in the course of scientific investigation and experimentation by researchers and staff at the science center. The data accession and retention policies employed by the Woods Hole Coastal and Marine Science Center Data Library are based on scientific need and the National Archives and Records Administration standards for Federal records retention. Criteria for inclusion of data and records into the Data Library, the scope of the Data Library holdings, and operating procedures for the management and running of the library are designed to support the research operations of the U.S. Geological Survey. This report explains the roles and detailed responsibilities of library and scientific staff, and provides step-by-step instructions for managing the collections of the Woods Hole Coastal and Marine Science Center Data Library.

Open-File Report↗

USGS2010

Accounting for intracell flow in models with emphasis on water table recharge and stream-aquifer interaction: 2. A procedure

Intercepted intracell flow, especially if cell includes water table recharge and a stream ((sink), can result in significant model error if not accounted for. A procedure utilizing net flow per cell ( F n ) that accounts for intercepted intracell flow can be used for both steady state and transient simulations. Germane to the procedure is the determination of the ratio of area of influence of the interior sink to the area of the cell ( A i / A c ). A i is the area in which water table recharge has the potential to be intercepted by the sink. Determining A i / A c requires either a detailed water table map or observation of stream conditions within the cell. A proportioning parameter M , which is equal to 1 or slightly less and is a function of cell geometry, is used to determine how much of the water that has potential for interception is intercepted by the sink within the cell. Also germane to the procedure is the determination of the flow across the streambed ( F s ), which is not directly a function of cell size, due to difference in head between the water level in the stream and the potentiometric surface of the aquifer underlying the streambed. The use of F n for steady state simulations allows simulation of water levels without utilizing head-dependent or constant head boundary conditions which tend to constrain the model-calculated water levels, an undesirable result if a comparison of measured and calculated water levels is being made. Transient simulations of streams usually utilize a head-dependent boundary condition and a leakance value to model a stream. Leakance values for each model cell can be determined from a steady state simulation, which used the net flow per cell procedure. For transient simulation, F n would not include F s . Also, for transient simulation it is necessary to check F n at different time intervals because M and A i / A c are not constant and change with time. The procedure was used successfully in two different models of the aquifer system in the Ozarks. The use of F n was essential to the two model studies because most model cells in both models contained water table recharge and multiple sinks.

Water Resources Research↗

USGS2024

Semi-automated methods to develop a unified geographic information system dataset

Geospatial data describing the topography, natural features, human-built features, and land uses of a particular area or region can come from independent data providers and, therefore, vary in format, data encoding, and geographic coverage. Because of the complexity of the processes and procedures required for unifying these heterogeneous data into a dataset with consistent format, encoding, and coverage, fully automated procedures for data unification do not exist. However, a combination of manual and automated procedures—semi-automated methods—can substantially reduce the time required for data unification while improving accuracy. This report presents three semi-automated data-unification methods in detail. Although these methods are not new in principle, their details are the result of original development work, and they serve as examples that can be reused, adapted, or generalized to provide head starts to future data-unification projects. The format of this report can be used and refined to encourage the publication of future reports and more widespread sharing of semi-automated methods.

Techniques and Methods↗

USGS2013

A fluid-driven earthquake swarm on the margin of the Yellowstone caldera

Over the past several decades, the Yellowstone caldera has experienced frequent earthquake swarms and repeated cycles of uplift and subsidence, reflecting dynamic volcanic and tectonic processes. Here, we examine the detailed spatial-temporal evolution of the 2010 Madison Plateau swarm, which occurred near the northwest boundary of the Yellowstone caldera. To fully explore the evolution of the swarm, we integrated procedures for seismic waveform-based earthquake detection with precise double-difference relative relocation. Using cross-correlation of continuous seismic data and waveform templates constructed from cataloged events, we detected and precisely located 8710 earthquakes during the three-week swarm, nearly four times the number of events included in the standard catalog. This high-resolution analysis reveals distinct migration of earthquake activity over the course of the swarm. The swarm initiated abruptly on January 17, 2010 at about 10 km depth and expanded dramatically outward (both shallower and deeper) over time, primarily along a NNW-striking, ~55º ENE-dipping structure. To explain these characteristics, we hypothesize that the swarm was triggered by the rupture of a zone of confined high-pressure aqueous fluids into a pre-existing crustal fault system, prompting release of accumulated stress. The high-pressure fluid injection may have been accommodated by hybrid shear and dilatational failure, as is commonly observed in exhumed hydrothermally affected fault zones. This process has likely occurred repeatedly in Yellowstone as aqueous fluids exsolved from magma migrate into the brittle crust, and it may be a key element in the observed cycles of caldera uplift and subsidence.

Wyoming↗

USGS1978

Flood damage assessment using computer-assisted analysis of color infrared photography

Use of digitized aerial photographs for flood damage assessment in agriculture is new and largely untested. However, under flooding circumstances similar to the 1975 Red River Valley flood, computer-assisted techniques can be extremely useful, especially if detailed crop damage estimates are needed within a relatively short period of time. Airphoto interpretation techniques, manual or computer-assisted, are not intended to replace conventional ground survey and sampling procedures. But their use should be considered a valuable addition to the tools currently available for assessing agricultural flood damage.

Journal of Soil and Water Conservation↗

USGS2006

An overview of the LANDFIRE Prototype Project

This chapter describes the background and design of the Landscape Fire and Resource Management Planning Tools Prototype Project, or LANDFIRE Prototype Project, which was a sub-regional, proof-of-concept effort designed to develop methods and applications for providing the high-resolution data (30-m pixel) needed to support wildland fire management and to implement the National Fire Plan and Healthy Forests Restoration Act. In addition, this chapter provides synopses of the many interrelated procedures necessary for development of the 24 LANDFIRE Prototype products (see table 1 and appendix 2-A). Throughout this chapter, direction is provided for where, in this report and elsewhere, additional detailed information is available.

General Technical Report↗

USGS2021

Progress in protecting air travel from volcanic ash clouds

The Eyjafjallajökull eruption of 2010 demonstrated the far-reaching impact of ash clouds and the vulnerability of our jet-based society to them, prompting a review of procedures to detect, warn, and forecast ash cloud hazards to aviation. The years since 2010 have seen marked improvements in satellite technology, more accurate ash-dispersion models that integrate simulations with observations, and more thoroughly vetted and harmonized procedures for forecasting and communicating hazards. In the coming decade, we expect these trends to continue, with formal warning products migrating from text and simplified maps to 4D data streams. This paper details some of these advancements and challenges ahead.

Bulletin of Volcanology↗