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At least 1,567 records · Page 87Linked to original sources
USGS1986

Recent developments in the U. S. Geological Survey's Landsat image mapping program

At the 1984 ASPRS-ACSM Convention in Washington, D. C. a paper on 'The Emerging U. S. Geological Survey Image Mapping Program' was presented that discussed recent satellite image mapping advancements and published products. Since then Landsat image mapping has become an integral part of the National Mapping Program. The Survey currently produces about 20 Landsat multispectral scanner (MSS) and Thematic Mapper (TM) image map products annually at 1:250,000 and 1:100,000 scales, respectively. These Landsat image maps provide users with a regional or synoptic view of an area. The resultant geographical presentation of the terrain and cultural features will help planners and managers make better decisions regarding the use of our national resources.

Conference Paper↗
USGS1986

Repetitive digital NOAA-AVHRR data for Alaskan engineering and scientific applications

Selected digitally enhanced NOAA - Advanced Very High Resolution Radiometer (AVHRR) images taken by the NOAA 6, 7, 8 and 9 Polar Orbiting Satellites demonstrate the capability and application of repetitive low-resolution satellite data to Alaska's engineering and science community. Selected cloud-free visible and thermal infrared images are enhanced to depict distinct oceanographic and geologic processes along Alaska's west coast and adjacent seas. Included are the advance of the Bering Sea ice field, transport of Yukon River sediment into Norton Sound, and monitoring of plume trajectories from the Mount Augustine volcanic eruptions. Presented illustrations are representative of the 94 scenes in a cooperative USGS EROS/NOAA Alaskan AVHRR Digital Archive. This paper will discuss the cooperative efforts in establishing the first year data set and identifying Alaskan applications.

Alaska↗
USGS1990

Urban hydrology in the desert, Antelope Valley, California

A study of urban hydrology in Antelope Valley includes data collection, analysis of rainfall and runoff frequencies, and comparison of results from various rainfall-runoff models. This paper discusses only parts of the project that include data collection and frequency analyses.

Conference Paper↗
USGS1990

Computational open-channel hydraulics for movable-bed problems

As a major branch of computational hydraulics, notable advances have been made in numerical modeling of unsteady open-channel flow since the beginning of the computer age. According to the broader definition and scope of 'computational hydraulics,' the basic concepts and technology of modeling unsteady open-channel flow have been systematically studied previously. As a natural extension, computational open-channel hydraulics for movable-bed problems are addressed in this paper. The introduction of the multimode method of characteristics (MMOC) has made the modeling of this class of unsteady flows both practical and effective. New modeling techniques are developed, thereby shedding light on several aspects of computational hydraulics. Some special features of movable-bed channel-flow simulation are discussed here in the same order as given by the author in the fixed-bed case.

Conference Paper↗
USGS1990

Relative efficiency of four parameter-estimation methods in steady-state and transient ground-water flow models

Parameters in numerical ground-water flow models have been successfully estimated using nonlinear-optimization methods such as the modified Gauss-Newton (GN) method and conjugate-direction methods. This paper investigates the relative efficiency of GN and three conjugate-direction parameter-estimation methods on two-dimensional, steady-state and transient ground-water flow test cases. The steady-state test cases are included to compare the performance of the algorithm with published examples. The three conjugate-direction methods are the Fletcher-Reeves (FR) and quasi-Newton (QN) regression methods, and combination Fletcher-Reeves quasi-Newton (FR-QN). All three are combined with Newton's method of calculating step size. The numerical ground-water flow model is described by McDonald and Harbaugh.

Conference Paper↗
USGS1989

Criteria for a sediment data set

The transport of sediment through a hydrologic system or basin is an extremely complex phenomenon. Many factors affect this movement. Criteria are established for an 'ultimate' or complete sediment data set, and guidelines are given for the collection of alluvial data. The paper describes what parameters need to be measured and stored to obtain a complete sediment and hydraulic data set that could be used to compute sediment transport using any prominently known sediment-transport equation. The criteria address only the collection of data for noncohesive sediment.

Conference Paper↗
USGS1989

Changes along a seawall and natural beaches: Fourchon, LA

This paper compares shoreline and beach morphology changes and responses to storms from 1985 to 1988 along sections of a rapidly eroding coast at the Bayou Lafourche headland, Louisiana. A beach consisting of a cement-filled bag seawall and nourishment was compared with natural beaches to the west and east of the project. Local patterns of beach response could be attributed to several recent processes and historical conditions. Hurricane Gilbert, which made landfall in Mexico, caused about 70% of the sediment loss on both the artificially-stablized and the natural shorelines over this three-year period.

Conference Paper↗
USGS1989

Survey of three-dimensional numerical estuarine models

This paper surveys the existing 3-D estuarine hydrodynamic and solute transport models by a review of the commonly used assumptions and approximations, and by an examination of the methods of solution. The model formulations, methods of solution, and known applications are surveyed and summarized in tables. In conclusion, the authors present their modeling philosophy and suggest future research needs.

Conference Paper↗
USGS1991

Data standardization. The key to effective management

Effective management of the nation's water resources is dependent upon accurate and consistent hydrologic information. Before the emergence of environmental concerns in the 1960's, most hydrologic information was collected by the U.S. Geological Survey and other Federal agencies that used fairly consistent methods and equipment. In the past quarter century, however, increased environmental awareness has resulted in an expansion of hydrologic data collection not only by Federal agencies, but also by state and municipal governments, university investigators, and private consulting firms. The acceptance and use of standard methods of collecting and processing hydrologic data would contribute to cost savings and to greater credibility of flow information vital to responsible assessment and management of the nation's water resources. This paper traces the evolution of the requirements and uses of open-channel flow information in the U.S., and the sequence of efforts to standardize the methods used to obtain this information in the future. The variable nature of naturally flowing rivers results in continually changing hydraulic properties of their channels. Those persons responsible for measurement of water flowing in open channels (streamflow) must use a large amount of judgement in the selection of appropriate equipment and technique to obtain accurate flow information. Standardization of the methods used in the measurement of streamflow is essential to assure consistency of data, but must also allow considerable latitude for individual judgement to meet constantly changing field conditions.

Conference Paper↗
USGS1992

Computer simulation of dry layered granular flow down an incline composed of grains

Experiments show that gravity-driven dry granular flows are essentially layered for smooth spheres. This paper describes layer-to-layer interaction in the flow. Assuming two-dimensional flow and neglecting the interaction of grains within the same layer, one may idealize the problem as an elastic sphere under external forces moving down an incline within a layer of identical spheres placed equally apart. The moving sphere is thus subjected to the total gravitational force which includes the weight of a specified number of layers of spheres above it and its own weight. With such a mechanical approach, estimates can be made for the magnitudes of collisional and non-collisional stresses.

Conference Paper↗
USGS1991

Is April to July runoff really decreasing in the Western United States?

Global warming has been the topic of a great deal of heated discussion and debate in recent years, both in the lay press and in scientific journals. The debate is about whether we are beginning to detect signs of a buildup of greenhouse gases on a global scale. A major part of the debate concerns the possible effects on climate and on the future availability of water resources. The ongoing drought in California has added impetus to the debate, serving notice of the serious consequences of any prolonged decrease in the availability of adequate water supplies. This paper has three primary objectives: (1) To evaluate the ramifications of using fractional runoff rather than total runoff to define trends in runoff; (2) to analyze additional streamflow data for the presence and extent of trends in annual and seasonal runoff volume for the conterminous Western United States; and (3) to examine the influence of the current California drought on indicators of trend.

Conference Paper↗
USGS1991

Assessing the effects of microbial metabolism and metabolities on reservoir pore structure

The effect of microbial treatment on pore structure of sandstone and carbonatereservoirs was determined. Understanding how different bacterial strains and their metabolic bioproducts affect reservoir pore structure will permit the prudent application of microorganisms for enhanced oil recovery. The microbial strains tested included Clostridium acetobutylicum, a polymer-producing Bacillus strain, and an unidentified halophilic anaerobe that mainly produced acids and gases. Electrical conductivity, absolute permeability, porosity and centrifuge capillary pressure were used to examine rock pore structures. Modifications of the pore structure observed in the laboratory cores included pore enlargement due to acid dissolution of carbonates and poare throat reduction due to biomass plugging. This paper shows that careful selection of microbes based on proper understanding of the reservoir petrophysical characteristics is necessary for applications of microbially enhanced oil recovery. These methods and results can be useful to field operators and laboratory researchers involved in design and screening of reservoirs for MEOR. The methods are also applicable in evaluation of formation damage caused by drilling, injection or completion fluids or stimulation caused by acids.

Conference Paper↗
USGS1991

Use of electronic microprocessor-based instrumentation by the U.S. geological survey for hydrologic data collection

The U.S. Geological Survey is acquiring a new generation of field computers and communications software to support hydrologic data-collection at field locations. The new computer hardware and software mark the beginning of the Survey's transition from the use of electromechanical devices and paper tapes to electronic microprocessor-based instrumentation. Software is being developed for these microprocessors to facilitate the collection, conversion, and entry of data into the Survey's National Water Information System. The new automated data-collection process features several microprocessor-controlled sensors connected to a serial digital multidrop line operated by an electronic data recorder. Data are acquired from the sensors in response to instructions programmed into the data recorder by the user through small portable lap-top or hand-held computers. The portable computers, called personal field computers, also are used to extract data from the electronic recorders for transport by courier to the office computers. The Survey's alternative to manual or courier retrieval is the use of microprocessor-based remote telemetry stations. Plans have been developed to enhance the Survey's use of the Geostationary Operational Environmental Satellite telemetry by replacing the present network of direct-readout ground stations with less expensive units. Plans also provide for computer software that will support other forms of telemetry such as telephone or land-based radio.

Conference Paper↗
USGS1991

One perspective on spatial variability in geologic mapping

This paper discusses some of the differences between geologic mapping and soil mapping, and how the resultant maps are interpreted. The role of spatial variability in geologic mapping is addressed only indirectly because in geologic mapping there have been few attempts at quantification of spatial differences. This is largely because geologic maps deal with temporal as well as spatial variability and consider time, age, and origin, as well as composition and geometry. Both soil scientists and geologists use spatial variability to delineate mappable units; however, the classification systems from which these mappable units are defined differ greatly. Mappable soil units are derived from systematic, well-defined, highly structured sets of taxonomic criteria; whereas mappable geologic units are based on a more arbitrary hierarchy of categories that integrate many features without strict values or definitions. Soil taxonomy is a sorting tool used to reduce heterogeneity between soil units. Thus at the series level, soils in any one series are relatively homogeneous because their range of properties is small and well-defined. Soil maps show the distribution of soils on the land surface. Within a map area, soils, which are often less than 2 m thick, show a direct correlation to topography and to active surface processes as well as to parent material.

Conference Paper↗
USGS1992

Remote sensing of water clarity and suspended sediments in coastal waters

Processing of data for estimation of suspended sediment concentrations and water clarity in turbid coastal water requires three components: (1) correction of raw data to water reflectance; (2) establishment of appropriate general models relating reflectance characteristics to materials in the water; and (3) determination of the coefficients of the models appropriate for the area under study. This paper presents equations and procedures appropriate for this processing. It provides example coefficients and data for the NOAA advanced very high resolution radiometer, which is the most appropriate sensor for investigating larger estuaries and turbid coastal systems until the launch of an ocean color imager (SeaWiFS) in late 1993.

Conference Paper↗
USGS1991

Implications of accelerated sea-level rise on Louisiana coastal environments

Natural and human-induced processes have combined to produce high rates of relative sea-level rise and coastal land loss in Louisiana. This paper presents historical trends in sea-level rise and the implication of predicted accelerated rise scenarios on Louisiana's coastal environments. Mean eustatic sea-level in the Gulf of Mexico is 0.23 cm/yr. In Louisiana, relative sea-level rise, which combines eustacy and subsidence, averages from 0.50 cm/yr in the chenier plain to 1.0 cm/yr in the delta plain. Subsidence due to the compaction of Holocene sediments is believed to be the major component influencing these high rates of rise. Subsidence contributes up to 80% of the observed relative sea-level rise in coastal Louisiana. The Environmental Protection Agency (EPA) predicts the rate of sea-level rise to increase over the next century due to global climate change. If these predictions are accurate, a dramatic increase in the coastal land loss conditions in Louisiana can be expected.

Conference Paper↗
USGS1992

Numerical simulation of a sphere moving down an incline with identical spheres placed equally apart

This paper describes a numerical study of an elastic sphere moving down an incline with a string of identical spheres placed equally apart. Two momentum equations and a moment equation formulated for the moving sphere are solved numerically for the instantaneous velocity of the moving sphere on an incline with different angles of inclination. Input parameters for numerical simulation include the properties of the sphere (the radius, density, Poison's ratio, and Young's Modulus of elasticity), the coefficient of friction between the spheres, and a damping coefficient of the spheres during collision.

Conference Paper↗
USGS1994

Critical and supercritical flows in two unstable, mountain rivers, Toutle river system, Washington

Critical and supercritical flows are generally considered to be rare occurrences in natural river channels. This paper presents data and results pertaining to the existence of measured critical and supercritical flows at gaging stations on the North Fork Toutle River (NFT) and Toutle River main stem (TR). The data set includes 930 discharge measurements made by the staff of the U.S. Geological Survey, Cascades Volcano Observatory, between 1980 and 1989.

Conference Paper↗