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Full-Text Articles in Physical Sciences and Mathematics
Numerical Methods 101 - Convergence Of Numerical Models, David B. Thompson
Numerical Methods 101 - Convergence Of Numerical Models, David B. Thompson
United States Geological Survey: Staff Publications
A numerical model is convergent if and only if a sequence of model solutions with increasingly refined solution domains approaches a fixed value. Furthermore, a numerical model is consistent only if this sequence converges to the solution of the continuous equations which govern the physical phenomenon being modeled. Given that a model is consistent, it is insufficient to apply it to a problem without testing for sensitivity to the size of the time and distance steps which form the discrete approximation of the solution domain. That is, convergence testing is a required component of any modeling study.
Two models were …
Vedernikov's Number As A Measure Of Flow Stability, Cheng-Lung Chen
Vedernikov's Number As A Measure Of Flow Stability, Cheng-Lung Chen
United States Geological Survey: Staff Publications
In 1946, Vedernikov developed a stability criterion for uniform flow in open channels. A global parameter proposed by Vedernikov has been widely accepted as a measure of flow stability. Recognizing the significance of the role of the parameter playing in the stability of open-channel flows, hydraulicians have thenceforth called it the Vedernikov number. Alternatively, the Vedernikov number may be considered as an extended form of the Froude number because it equals the Froude number mUltiplied by an exponent of the hydraulic radius in the uniform-flow formula and a shape factor of channel section. A stability criterion can thus be formulated …
A Brief Literature Review Of Open-Channel Current Meter Testing, Kirk G. Thibodeaux
A Brief Literature Review Of Open-Channel Current Meter Testing, Kirk G. Thibodeaux
United States Geological Survey: Staff Publications
The U.S. Geological Survey (USGS) has undertaken the task of conducting an evaluation of the USGS's standard water-flow current meter, the Price type-AA current meter. The first part of the USGS's task was to conduct a comprehensive literature review to determine the extent and types of testing that has been conducted to evaluate the performance of various types of current meters used for open-channel flow measurements. The meter types included in the review were the vertical-axis mechanical type, the horizontal-axis mechanical type, the electromagnetic type, and the point-velocity acoustic (ultrasonic) type current meters. The review revealed that current meters have …
First- And Second-Order Patterns Of Stress In The Lithosphere: The World Stress Map Project, Mary Lou Zoback
First- And Second-Order Patterns Of Stress In The Lithosphere: The World Stress Map Project, Mary Lou Zoback
United States Geological Survey: Staff Publications
To date, more than 7300 in situ stress orientations have been compiled as part of the World Stress Map project. Of these, over 4400 are considered reliable tectonic stress indicators, recording horizontal stress orientations to within < ±25 °. Remarkably good correlation is observed between stress orientations deduced from in situ stress measurements and geologic observations made in the upper 1-2 km, well bore breakouts extending to 4-5 km depth and earthquake focal mechanisms to depths of-20 km. Regionally uniform stress orientations and relative magnitudes permit definition of broad-scale regional stress patterns often extending 20-200 times the approximately 20-25 km thickness of the upper brittle lithosphere. The "first-order" midplate stress fields are believed to be largely the result of compressional forces applied at plate boundaries, primarily ridge push and continental collision. The orientation of the intraplate stress field is thus largely controlled by the geometry of the plate boundaries. There is no evidence of large lateral stress gradients (as evidenced by lateral variations in stress regime) which would be expected across large plates if simple resistive or driving basal drag tractions (parallel or antiparallel to absolute motion) controlled the intraplate stress field. Intraplate areas of active extension are generally associated with regions of high topography: western U.S. Cordillera, high Andes, Tibetan plateau, western Indian Ocean plateau. Buoyancy stresses related to crustal thickening and/or lithospheric thinning in these regions dominate the intraplate compressional stress field due to plate-driving forces. These buoyancy forces are just one of several categories of "second-order" stresses, or local perturbations, that can be identified once the first-order stress patterns are recognized. These second-order stress fields can often be associated with specific geologic or tectonic features, for example, lithospheric flexure, lateral strength contrasts, as well as the lateral density contrasts which give rise to buoyancy forces. These second-order stress patterns typically have wavelengths ranging from 5 to 10+ times the thickness of the brittle upper lithosphere. A two-dimensional analysis of the amount of rotation of regional horizontal stress orientations due to a superimposed local stress constrains the ratio of the magnitude of the horizontal regional stress differences to the local uniaxial stress. For a detectable rotation of 15 °, the local horizontal uniaxial stress must be at least twice the magnitude of the regional horizontal stress differences. Examples of local rotations of SHmax orientations include a 750-85 ° rotation on the
northeastern Canadian continental shelf possibly related to margin-normal extension derived from sediment-loading flexural stresses, a 50 °-60 ° rotation within the East African rift relative to western Africa due to extensional buoyancy forces caused by lithospheric thinning, and an approximately 90 ° rotation along the northern margin of the Paleozoic Amazonas rift in central Brazil. …
Introduction To Special Section On The Cajon Pass Scientific Drilling Project, Mark D. Zoback, Arthur H. Lachenbruch
Introduction To Special Section On The Cajon Pass Scientific Drilling Project, Mark D. Zoback, Arthur H. Lachenbruch
United States Geological Survey: Staff Publications
Over the past few decades a generally accepted conceptual model for the thermomechanics of the San Andreas fault was based on three factors believed to have been supported by observation: (1) maximum horizontal shear stress increases with depth in the crust at the rate of 7-8 MPa/km (as indicated by measurements in relatively shallow boreholes), roughly the same rate of shear stress increase as in other regions [e.g., McGarr et al., 1982], (2) the maximum horizontal stress direction in the vicinity of the fault was oriented at about 300-45 ° to its strike (as indicated by the predominance of right-lateral …
A Reconnaissance Study Of Herbicides And Their Metabolites In Surface Water Of The Midwestern United States Using Immunoassay And Gas Chromatography/Mass Spectrometry, E. Michael Thurman, Donald A. Goolsby, Michael Meyer, Margaret Mills, Michael L. Pomes, Dana W. Kolpin
A Reconnaissance Study Of Herbicides And Their Metabolites In Surface Water Of The Midwestern United States Using Immunoassay And Gas Chromatography/Mass Spectrometry, E. Michael Thurman, Donald A. Goolsby, Michael Meyer, Margaret Mills, Michael L. Pomes, Dana W. Kolpin
United States Geological Survey: Staff Publications
Preemergent herbicides and their metabolites, particularly atrazine, deethylatrazine, and metolachlor, persisted from 1989 to 1990 in the majority of rivers and streams in the midwestern United States. In spring, after the application of herbicides, the concentrations of atrazine, alachlor, and simazine were frequently 3-10 times greater than the U.S. Environmental Protection Agency maximum contaminant level (MCL). The concentration of herbicides exceeded the MCLs both singly and in combination. Two major degradation products of atrazine (deisopropylatrazine and deethylatrazine) also were found in many of the streams. The order of persistence of the herbicides and their metabolites in surface water was atrazine …
Mesh-Generating Computer Program For The Feswms-2dh Surface-Water Flow Model, Kirk G. Thibodeaux
Mesh-Generating Computer Program For The Feswms-2dh Surface-Water Flow Model, Kirk G. Thibodeaux
United States Geological Survey: Staff Publications
A mesh-generating computer program, GNMESH, has been developed to generate two-dimensional finite element meshes for the U.S. Federal Highway Administration's FESWMS-2DH, a two-dimensional depth averaged finite element flow model. GNMESH uses a modified mapping technique that incorporates piecewise Hermitian and weighted interpolation schemes to layout the generated mesh within given or calculated flow tubes. Minimum required input data for GNMESH is required when the program is run using its default settings. These input data consists of the X, Y, and Z coordinates of points defining a minimum of three cross sections, the roughness coefficients at the given cross sections, an …
Flux Of Metals Between Sediment And The Water Column, N. S. Simon, K. O. Dennen
Flux Of Metals Between Sediment And The Water Column, N. S. Simon, K. O. Dennen
United States Geological Survey: Staff Publications
The role of nitrogen-containing compounds in the flux of metals between sediment and the overlying water column is discussed.
Rainfall-Runoff Relations For The Puget Sound Area, R. S. Dinicola
Rainfall-Runoff Relations For The Puget Sound Area, R. S. Dinicola
United States Geological Survey: Staff Publications
The characteristics of rainfall-runoff relations were hypothesized for the study area using existing information. These hypotheses were incorporated into the Hydrologic Simulation Program-FORTRAN, and the model was calibrated concurrently at 21 stream-gage sites in the study area. The simulation errors after model calibration were not large enough to reject the hypothesized characteristics. A proxy-basin validation effort was performed.
Watershed Models For Resources Management Decisions, Alan M. Lumb
Watershed Models For Resources Management Decisions, Alan M. Lumb
United States Geological Survey: Staff Publications
Comprehensive hydrologic analyses can be very effective for the assessment of hydrologic effects of land use and climate changes, but the costs and expertise is often prohibitive. Progress has been made in four areas to reduce the costs and expertise required: (1) Watershed Data Management (WDM) system for the storage and retrieval of data used and generated by the model, (2) an expert system for the calibration of the model, (3) use of Geographical Information Systems to generate distributed parameters for the model, and (4) easy to use software for applications of the model.
Bridge Scour Data Management, Mark N. Landers
Bridge Scour Data Management, Mark N. Landers
United States Geological Survey: Staff Publications
A Bridge Scour Data Management System has been developed by the U.S. Geological Survey to support preparation, compilation, and analysis of bridge scour measurement data. Users may interactively store, retrieve, select, update, and display bridge scour and associated data. Interactive processing makes use of full-screen menus and form fill-ins, and an instruction window. Optional help and limits windows provide additional information for each of about 150 items in the data set for each bridge-scour site. The data set items include all of the essential information from a detailed scour measurement. Each data set has four categories of information: site data; …
Modeling Flow And Flood-Plain Storage In A Tidally Affected River, A. G. Strickland, Jerad D. Bales
Modeling Flow And Flood-Plain Storage In A Tidally Affected River, A. G. Strickland, Jerad D. Bales
United States Geological Survey: Staff Publications
A one-dimensional, unsteady-flow model was calibrated, validated, and tested for a 30.4-mile reach of the tidally affected Roanoke River, North Carolina. The model includes a storage reservoir to represent the two-dimensional processes associated with flood-plain storage and release in the one-dimensional flow model. Simulated and measured water levels differed by less than 0.5 foot, and the average absolute difference between simulated and measured flows was 7 percent.
Usgs Urban Stonnwater Investigations In The Dallas-Fort Worth, Texas Metroplex, R. Brad Jennings, Tim H. Raines, Lucia G. Colangione
Usgs Urban Stonnwater Investigations In The Dallas-Fort Worth, Texas Metroplex, R. Brad Jennings, Tim H. Raines, Lucia G. Colangione
United States Geological Survey: Staff Publications
Stormwater runoff in urban and industrialized areas carries a considerable amount of pollutants to nearby lakes and streams. In an effort to control this source of pollution, the U.S. Environmental Protection Agency has issued stormwater regulations to control these discharges. Municipalities with a population of 100,000 or more must undertake a process to obtain permits to control the quality of their storm runoff. The Dallas-Fort Worth metroplex includes seven cities that must meet these regulations and obtain permits. The U.S. Geological Survey is assisting the North Texas Council of Governments and its associated cities in meeting the water science requirements …
In Situ Stress Measurements To 3.5 Km Depth In The Cajon Pass Scientific Research Borehole: Implications For The Mechanics Of Crustal Faulting, Mark D. Zoback, John H. Healy
In Situ Stress Measurements To 3.5 Km Depth In The Cajon Pass Scientific Research Borehole: Implications For The Mechanics Of Crustal Faulting, Mark D. Zoback, John H. Healy
United States Geological Survey: Staff Publications
Measurements of in situ stress orientation and magnitude at the site of the Cajon Pass research borehole have been made from depths of 0.9-3.5 km using the hydraulic fracturing technique and analysis of stress-induced well bore breakouts. The results of these measurements support two important conclusions about the mechanics of crustal faulting. First, the magnitudes of measured in situ stresses indicate ratios of shear to normal stress. on favorably oriented fault planes that are consistent with predictions based on Mohr-Coulomb theory and laboratory-determined coefficients of friction in the range of 0.6-1.0 assuming hydrostatic pore pressure (this is commonly known as …
United States Geological Survey Bridge Scour Evaluation Program In Texas, David D. Dunn, Henry R. Hejl Jr.
United States Geological Survey Bridge Scour Evaluation Program In Texas, David D. Dunn, Henry R. Hejl Jr.
United States Geological Survey: Staff Publications
The Federal Highway Administration has mandated that all bridges in the Federal Aid System crossing over water be evaluated for scour susceptibility. The United States Geological Survey and the Texas Department of Transportation (TXDOT) have initiated a multi-year, multi-phase program to develop scour evaluation and analysis procedures that will allow TXDOT to quickly and efficiently evaluate some 11,000 bridges crossing over water in the state.
Wspro Files For Slope-Area Computations, Janice M. Fulford
Wspro Files For Slope-Area Computations, Janice M. Fulford
United States Geological Survey: Staff Publications
A new program based on the U. S. Geological Survey slope-area program for indirectly computing peak discharges allows users to employ input data formats used by the water surface profile program WSPRO. The program source is written in Fortran 77 and can be ported easily to any computer that has standard Fortran 77 compilers. The program has been run on mini-computers and personal computers and does not use or require graphics capability, a color monitor, or a mouse.
Characteristics Of U.S. Geological Survey Discharge Measurements For Water Year 1990, Janice M. Fulford
Characteristics Of U.S. Geological Survey Discharge Measurements For Water Year 1990, Janice M. Fulford
United States Geological Survey: Staff Publications
The U.S. Geological Survey (USGS) Water Resources Division makes ten of thousands of stream discharge measurements each year throughout the United States and Puerto Rico. The majority of the measurements requires the use of point velocity instrumentation. Interest in new instrumentation technology and the performance of in-use instrumentation prompted a survey of current-meter usage and discharge measurement data for water year 1990. This paper is a summary of survey results: the velocity, discharge and depth ranges measured; the types of meters used; and the measurement problems encountered.
Stress-Strain Relation In Debris Flow Analysis, Chi-Hai Ling, Cheng-Lung Chen, Chyan-Deng Jan
Stress-Strain Relation In Debris Flow Analysis, Chi-Hai Ling, Cheng-Lung Chen, Chyan-Deng Jan
United States Geological Survey: Staff Publications
In debris flow analysis, the generalized viscop1astic fluid (GVF) model can be used as the constitutive equations. When the yield stress is negligible, the shear expression in the GVF model for simple shear flow reduces to r = µ1 (du/dz)n, where r is the shear stress, µ1 is the consistency index, du/dz is the shear rate, and n is the flow behavior index. In this paper the r versus du/dz relation is studied by running experiments with 14 mm dry glass spheres in a conveyor-belt flume. A comparison of the estimated r with the measured du/dz …
Topographic Effects On Stormflow Acidity, David Wolock
Topographic Effects On Stormflow Acidity, David Wolock
United States Geological Survey: Staff Publications
This paper describes the theoretical and observed effects of topography on stormflow acidity in upland, forested watersheds. The theoretical effects were determined by a sensitivity analysis using the hydrologic model TOPMODEL. The observed effects were determined by an analysis of topographic and stormflow acidity data collected from eight watersheds in Wales, Great Britain. Results of the analyses indicated that the observed effects of topography were consistent with the theoretical expectations; that is, topography has an important effect on flow path, and that flow path, in turn, has an effect on stormflow acidity.
Network Applications Of The Usgs Branch Model, Raymond W. Schaffranek
Network Applications Of The Usgs Branch Model, Raymond W. Schaffranek
United States Geological Survey: Staff Publications
Applications of a numerical model for simulating unsteady flow in dendritic or interconnected open-channel networks are presented to demonstrate the model's potential for addressing environmental problems and formulating engineering decisions in water-resources investigations. The model is computationally robust and readily adaptable to a broad spectrum of hydraulic conditions and open-channel configurations. The four-point, implicit, finite difference model has been implemented on numerous open-channel reaches and networks in support of various water-resources investigations conducted within the U.S. Geological Survey. In this paper, network applications of the model to a residential canal system in Cape Coral, Florida; to a distributary system of …
Incorporating Hydraulic Structures In An Open-Channel Model, Eric D. Swain
Incorporating Hydraulic Structures In An Open-Channel Model, Eric D. Swain
United States Geological Survey: Staff Publications
The open-channel flow model, BRANCH, is a routinely used numerical tool for modeling rivers, canals, and waterway networks. Although a simplified hydraulic structure representation is included in the model, no universal subroutine that can represent hydraulic structures by their rating curve equations has been included in the BRANCH model.
Accordingly, a subroutine has been developed that specifies flow through a structure by a stage-discharge relation. The structure flow equation is used to generate coefficients in the solution matrix that represent the structure in the same computational format as the open-channel flow equations. Field applications have shown that this new subroutine …
Sr-Isotope Record Of Quaternary Marine Terraces On The California Coast And Off Hawaii, Kenneth R. Ludwig, Daniel R. Muhs, Kathleen R. Simmons, James G. Moore
Sr-Isotope Record Of Quaternary Marine Terraces On The California Coast And Off Hawaii, Kenneth R. Ludwig, Daniel R. Muhs, Kathleen R. Simmons, James G. Moore
United States Geological Survey: Staff Publications
Strontium-isotopic ratios of dated corals have been obtained from submerged reefs formed during Quaternary glacial periods off the Hawaiian islands. These data, combined with data from deep-sea sediments, tightly constrain the secular variation of marine 87Sr/86Sr for the past 800,000 yr. Although long-term trends are apparent, no significant (>0.02‰), rapid (<100,000 yr) excursions in 87Sr/86Sr were resolved nor did we observe any samples with 87Sr/86Sr greater than that of modern seawater. Strontium in mollusks from elevated marine terraces formed during interglacial periods on the southern California coast show resolvable and consistent variations in …
Aminostratigraphy And Oxygen Isotope Stratigraphy Of Marine Terrace Deposits Palos Verdes Hills And San Pedro Areas Los Angeles County California, Daniel R. Muhs, Gifford H. Miller, Joseph F. Whelean, George L. Kennedy
Aminostratigraphy And Oxygen Isotope Stratigraphy Of Marine Terrace Deposits Palos Verdes Hills And San Pedro Areas Los Angeles County California, Daniel R. Muhs, Gifford H. Miller, Joseph F. Whelean, George L. Kennedy
United States Geological Survey: Staff Publications
Amino acid and oxygen isotope data for fossils from terraces of the Palos Verdes Hills and San Pedro areas in Los Angeles County California shed new light on the ages of terraces sea level history marine paleotemperatures and late Quaternary tectonics in this region Low terraces on the Palos Verdes peninsula correlate with the 80 ka and 125 ka sea level highstands that are also recorded as terraces on other coasts In San Pedro the Palos Verdes sand the deposit on what is mapped as the first terrace by Woodring and others 1946 was previously thought to be a single …
Stable Isotope Study Of Water-Rock Interaction And Ore Formation, Bayhorse Base And Precious Metal District, Idaho, Robert R. Seal Ii, Robert O. Rye
Stable Isotope Study Of Water-Rock Interaction And Ore Formation, Bayhorse Base And Precious Metal District, Idaho, Robert R. Seal Ii, Robert O. Rye
United States Geological Survey: Staff Publications
The Bayhorse base and precious metal district situated east of the Idaho batholiths in south-central Idaho. The ores occur near the Nevada Mountain granitic stock as veins cutting the lower Paleozoic Ramshorn Slate and the Garden Creek Phyllite, and as fillings around breccias fragments within the Bayhorse Dolomite. The veins are dominated by siderite and tetrahedrite, with lesser quartz and galena, whereas the breccias ores dominantly comprise only quartz and galena. Mineralization and intrusive activity were contemporaneous during Cretaceous time. Fluid inclusion and stable isotope data indicate that mineralization formed from hot (ca. 375° -225°C), CO2-rich (≤8.3 ± …
Residence Times In River Basins As Determined By Analysis Of Long-Term Tritium Records, Robert L. Michel
Residence Times In River Basins As Determined By Analysis Of Long-Term Tritium Records, Robert L. Michel
United States Geological Survey: Staff Publications
The US Geological Survey has maintained a network of stations to collect samples for the measurement of tritium concentrations in precipitation and streamflow since the early 1960s. Tritium data from outflow waters of river basins draining 4500-75 000 km2 are used to determine average residence times of water within the basins. The basins studied are the Colorado River above Cisco, Utah: the Kissimmee River above Lake Okeechobee, Florida; the Mississippi River above Anoka, Minnesota; the Neuse River above Streets Ferry Bridge near Vanceboro, North Carolina; the Potomac River above Point of Rocks. Maryland; the Sacramento River above Sacramento, California: …
The Last Interglacial-Glacial Transition In North America: Evidence From Uranium-Series Dating Of Coastal Deposits, Daniel R. Muhs
The Last Interglacial-Glacial Transition In North America: Evidence From Uranium-Series Dating Of Coastal Deposits, Daniel R. Muhs
United States Geological Survey: Staff Publications
Considerable uncertainty exists as to whether the last interglacial was relatively "short" (~10 ka) or "long" (-20-60 ka), although most investigators generally agree that the last interglacial correlates with all or part of deep-sea oxygen-isotope stage 5. A compilation of reliable U-series ages of marine terrace corals from deposits that have been correlated with isotope stage 5 indicates that there were three relatively high sea-level stands at ca 125-120 ka, ca. 105 ka, and ca. 85-80 ka, and these ages agree with the times of high sea level predicted by the Milankovitch orbital-forcing theory. At a number of localities, however, …
Superambient Heat Capacities Of Synthetic Stibnite, Berthierite, And Chalcostibite: Revised Thermodynamic Properties And Implications For Phase Equilibria, Robert R. Seal Ii, Richard A. Robie, Paul B. Barton Jr., Bruce Hemingway
Superambient Heat Capacities Of Synthetic Stibnite, Berthierite, And Chalcostibite: Revised Thermodynamic Properties And Implications For Phase Equilibria, Robert R. Seal Ii, Richard A. Robie, Paul B. Barton Jr., Bruce Hemingway
United States Geological Survey: Staff Publications
Stibnite (Sb2S3), berthierite (FeSb2S4), and chalcostibite (CuSbS2) are important antimony-bearing minerals. Stibnite is the main ore mineral of antimony and occurs as an important accessory in many epigenetic ore deposits, especially in later stages of deposition or in peripheral facies of mineralization. Berthierite is a common accessory mineral in antimony deposits. Its occurrence, particularly in gold-antimony deposits, has received considerable scientific attention. Furthermore, stibnite, berthierite, and chalcostibite represent important reference phases for understanding phase equilibria in more complex systems, such as those containing tetrahedrite-tennantite solid solutions.
Stress Field Constraints On Intraplate Seismicity In Eastern North America, Mary Lou Zoback
Stress Field Constraints On Intraplate Seismicity In Eastern North America, Mary Lou Zoback
United States Geological Survey: Staff Publications
Focal mechanisms of 32 North American midplate earthquakes (mb = 3.8-6.5) were evaluated to determine if slip is compatible with a broad-scale regional stress field derived from plate-driving forces and, if so, under what conditions (stress regime, pore pressure, and frictional coefficient). Using independent information on in situ stress orientations from well bore breakout and hydraulic fracturing data and assuming that the regional principal stresses are in approximately horizontal and vertical planes ( ± 10 °), the constraint that the slip vector represents the direction of maximum resolved shear stress on the fault plane was used to calculate relative …