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At least 1,531 records · Page 85Linked to original sources
USGS1985

U. S. G. S. MODULAR GROUND-WATER FLOW MODEL: DESIGNED TO BE UNDERSTOOD AND ADAPTED.

The paper discusses a carefully designed model program and its complementary complete description of all of the physical and mathematical concepts used in the model. The model program consists of a series of independent subroutines called modules. Modules are grouped by hydrologic function into 'packages. ' A report describing the model was written in three levels. At one level the hydrologic concepts on which the model is based are explained. The second level describes how the concepts were incorporated into the program. The third level describes specific modules in sufficient depth to permit modifications to the model.

Conference Paper↗
USGS1984

QUANTIFICATION OF IN-SITU GAS HYDRATES WITH WELL LOGS.

This study evaluates in detail the expected theoretical log responses and the actual log responses within one stratigraphically controlled hydrate horizon in six wells spaced throughout the Kuparuk Oil Field. Detailed examination of the neutron porosity and sonic velocity responses within the horizon is included. In addition, the theoretical effect of the presence of hydrates on the neutron porosity and sonic velocity devices has been examined in order to correct for such an effect on the calculation of formation properties such as porosity and hydrate saturation. Also presented in the paper is a technique which allows the conclusive identification of a potential hydrate occurrence.

Conference Paper↗
USGS1984

DISCRIMINATION OF GRANITOIDS AND MINERALIZED GRANITOIDS IN THE MIDYAN REGION, NORTHWESTERN ARABIAN SHIELD, SAUDI ARABIA, BY LANDSAT MSS DATA-ANALYSIS.

Landsat multispectral scanner (MSS) band and band-ratio databases of two scenes covering the Midyan region of northwestern Saudi Arabia were examined quantitatively and qualitatively to determine which databases best discriminate the geologic units of this semi-arid and arid region. Unsupervised, linear-discriminant cluster-analysis was performed on these two band-ratio combinations and on the MSS bands for both scenes. The results for granitoid-rock discrimination indicated that the classification images using the MSS bands are superior to the band-ratio classification images for two reasons, discussed in the paper. Yet, the effects of topography and material type (including desert varnish) on the MSS-band data produced ambiguities in the MSS-band classification results. However, these ambiguities were clarified by using a simulated natural-color image in conjunction with the MSS-band classification image.

Conference Paper↗
USGS1985

Geodetic accuracy of Landsat-4 Multispectral Scanner and Thematic Mapper data

EROS Data Center is evaluating the geodetic accuracy of Landsat-4 data from both the Multispectral Scanner (MSS) and Thematic Mapper (TM) processing systems. Geodetic accuracy is a measure of the precision of Landsat data registration to the Earth's figure. This paper describes a geodetic accuracy assessment of several MSS and TM scenes, based on the geodetic referencing information supplied on a standard Landsat 4 computer compatible tape.

Conference Paper↗
USGS1984

COORDINATION OF FEDERAL DIGITAL CARTOGRAPHIC ACTIVITIES.

Throughout the Federal Government, applications are emerging for spatial data bases that require digital cartographic data as a framework. This paper describes some major applications of spatial data in the Federal Government, and it discusses the extent to which these data needs are being coordinated. Efforts are outlined towards further coordination of digital cartographic data bases and production in the Federal Government.

Conference Paper↗
USGS1984

REMOTE-SENSING MINERAL DISCOVERIES IN THE MOJAVE DESERT OF CALIFORNIA.

As a result of remote sensing studies in the Mojave Desert of California three previously unknown stockwork molybdenum systems have been discovered. It is not known if economic deposits of molybdenum and associated minerals occur in these areas; there is, however, sufficient data to judge that these areas are worthy of further exploration. The purpose of this paper is to present case histories of two of these discoveries. These discoveries have been made from laboratory analyses of Landsat multispectral scanner images to map limonitic materials and from field reconnaissance to determine if the limonite is due to hydrothermal alteration. In those areas that seemed most promising, airborne spectrometer surveys were employed to mapped Al-OH minerals, and audio-magnetotelluric (AMT) and telluric-traversing surveys were performed to obtain information at depth.

Conference Paper↗
USGS1988

Stochastic system identification in structural dynamics

Recently, new identification methods have been developed by using the concept of optimal-recursive filtering and stochastic approximation. These methods, known as stochastic identification, are based on the statistical properties of the signal and noise, and do not require the assumptions of current methods. The criterion for stochastic system identification is that the difference between the recorded output and the output from the identified system (i.e., the residual of the identification) should be equal to white noise. In this paper, first a brief review of the theory is given. Then, an application of the method is presented by using ambient vibration data from a nine-story building.

Conference Paper↗
USGS1988

Federal microcomputer software for urban hydrology

The purpose of this paper is to describe the development, availability, and general use of selected urban hydrology microcomputer software developed by: U.S. Soil Conservation Service (SCS); U.S. Army Corps of Engineers, Hydrologic Engineering Center (HEC); U.S. Environmental Protection Agency (EPA); and U.S. Geological Survey (USGS). The discussion is limited to software used for design and planning for urban stormwater flows.

Conference Paper↗
USGS1988

Predicting tidal currents in San Francisco Bay using a spectral model

This paper describes the formulation of a spectral (or frequency based) model which solves the linearized shallow water equations. To account for highly variable basin bathymetry, spectral solutions are obtained using the finite element method which allows the strategic placement of the computation points in the specific areas of interest or in areas where the gradients of the dependent variables are expected to be large. Model results are compared with data using simple statistics to judge overall model performance in the San Francisco Bay estuary. Once the model is calibrated and verified, prediction of the tides and tidal currents in San Francisco Bay is accomplished by applying astronomical tides (harmonic constants deduced from field data) at the prediction time along the model boundaries.

Conference Paper↗
USGS1988

Calibration of water-velocity meters

The U.S. Geological Survey, Department of the Interior, as part of its responsibility to appraise the quantity of water resources in the United States, maintains facilities for the calibration of water-velocity meters at the Gulf Coast Hydroscience Center's Hydraulic Laboratory Facility, NSTL, Mississippi. These meters are used in hydrologic studies by the Geological Survey, U.S. Army Corps of Engineers, U.S. Department of Energy, state agencies, universities, and others in the public and private sector. This paper describes calibration facilities, types of water-velocity meters calibrated, and calibration standards, methods and results.

Conference Paper↗
USGS1986

ESTIMATION OF URBAN STORM-RUNOFF LOADS.

The United States was divided into three regions, on the basis of mean annual rainfall, to decrease the variability in storm-runoff constituent loads and to improve regression relations with basin and climatic characteristics. Multiple-regression analyses, in progress, are being refined to determine the best regression models for each of the storm-runoff constituent loads in each of the three regions. These techniques, when finalized, can be used to estimate storm-runoff constituent loads for gaged and ungaged urban watersheds. The preliminary standard errors of estimate for five constituents examined to date ranged from 54 to 223 percent, and the coefficients of determination (r**2) ranged from 0. 39 to 0. 94. Total storm rainfall and total contributing drainage area appear to be the most significant independent variables in the regression models. This paper is a progress report on preliminary results of estimating storm-runoff constituent loads for ungaged watersheds.

Conference Paper↗
USGS1986

STRONG-MOTION INSTRUMENTATION OF STRUCTURES IN CHARLESTON, SOUTH CAROLINA AND ELSEWHERE.

Instrumentation of structures is part of earthquake hazard mitigation program of many institutions, including the United States Geological Survey (USGS). The USGS Strong-Motion Instrumentation of Structures Program is designed to complement other programs and to implement its own, within budget and other constraints. This paper reviews the overall national effort, cites examples of structures implemented and describes progress made to date. A recent example of instrumentation of an eight-story building in Charleston, South Carolina is documented.

Conference Paper↗
USGS1986

ANALYSIS OF THE U. S. GEOLOGICAL SURVEY STREAMGAGING NETWORK.

This paper summarizes the results from the first 3 years of a 5-year cost-effectiveness study of the U. S. Geological Survey streamgaging network. The objective of the study is to define and document the most cost-effective means of furnishing streamflow information. In the first step of this study, data uses were identified for 3,493 continuous-record stations currently being operated in 32 States. In the second step, evaluation of alternative methods of providing streamflow information, flow-routing models, and regression models were developed for estimating daily flows at 251 stations of the 3,493 stations analyzed. In the third step of the analysis, relationships were developed between the accuracy of the streamflow records and the operating budget. The existing streamgaging networks in four Districts were further analyzed to determine the impacts that satellite telemetry would have on the cost effectiveness. Satellite telemetry was not found to be cost effective on the basis of hydrologic-data collection alone, given present cost of equipment and operation.

Conference Paper↗
USGS1989

High-resolution two dimensional advective transport

The paper describes a two-dimensional high-resolution scheme for advective transport that is based on a Eulerian-Lagrangian method with a flux limiter. The scheme is applied to the problem of pure-advection of a rotated Gaussian hill and shown to preserve the monotonicity property of the governing conservation law.

Conference Paper↗
USGS1989

Recent progress on hydrodynamic modeling of San Francisco Bay, California

A hydrodynamic modeling study of the effects of freshwater inflow on circulation and mixing in San Francisco Bay has been underway since 1985. This paper describes the multidimensional hydrodynamic models being used on the study and review recent progress with their applications. Particular modeling considerations for San Francisco Bay and future modeling plans are discussed.

Conference Paper↗
USGS1989

Regionalization of flood characteristics

Regionalization procedures are used to transfer flood characteristics from gaged to ungaged locations. These procedures are an extension of the gaging network that allows planners and designers to make estimates of flood frequency at ungaged sites of interest. The U.S. Geological Survey has a long time involvement in the development of these regionalization procedures. This paper describes the evolution of these regionalization procedures from the index-flood procedure used in the 1940's to the multiple regression procedure based on generalized least squares that is currently being used.

Conference Paper↗
USGS1987

NONHOMOGENEOUS TERMS IN THE UNSTEADY FLOW EQUATIONS: MODELING ASPECTS.

A study is in progress to identify the relative significance, effects, and benefits attributable to the use of one-dimensional, unsteady, open-channel, flow-simulation models employing a variety of nonhomogeneous terms in their equation formulations. Nonhomogeneous terms being analyzed include those representing bed slope, frictional resistance, nonprismatic channel geometry, lateral flow, and (surface) wind stress. After an initial theoretical discussion, the results of a set of numerical experiments are presented that demonstrate cause-and-effect relationships and intercomparisons achieved by neglect or improper treatment of important nonhomogeneous terms. Preliminary results of this study are discussed and presented in this paper, both in the form of qualitative considerations and quantitative tabular findings. These results are expected to yield a definitive set of guidelines and suggestions useful to model engineers.

Conference Paper↗
USGS1989

Simulated water-quality changes in detention basins

A study has begun to simulate movement of stormflow through detention basins at four locations in the Irondequoit Creek watershed and determine the effect on peak flow and water quality. Two types of basins were simulated for each site - a temporary-storage basin, which impounds water during high flows, and a maximum-storage basin, which maintains a permanent pool of water. This paper describes the simulated stormflow attenuation and suspended-sediment removal by both types of basins at the four sites. It also examines the effect of particle-size distribution on sediment removal in both types of basins; the relation of suspended-sediment loads to adsorbed phosphorus, lead, and zinc loads; and the effect that these basins could have on the transport of suspended constituents to Irondequoit Bay, to which Irondequoit Creek is the only large tributary.

Conference Paper↗