Geology Reports⌕ Search

SEARCH · Geology Reports

Results for “Processes”

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

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

At least 1,369 records · Page 76Linked to original sources
USGS1985

ANNIE - INTERACTIVE PROCESSING OF DATA BASES FOR HYDROLOGIC MODELS.

ANNIE is a data storage and retrieval system that was developed to reduce the time and effort required to calibrate, verify, and apply watershed models that continuously simulate water quantity and quality. Watershed models have three categories of input: parameters to describe segments of a drainage area, linkage of the segments, and time-series data. Additional goals for ANNIE include the development of software that is easily implemented on minicomputers and some microcomputers and software that has no special requirements for interactive display terminals. Another goal is for the user interaction to be based on the experience of the user so that ANNIE is helpful to the inexperienced user and yet efficient and brief for the experienced user. Finally, the code should be designed so that additional hydrologic models can easily be added to ANNIE.

Conference Paper↗
USGS1984

PROCESSING OF SCANNED IMAGERY FOR CARTOGRAPHIC FEATURE EXTRACTION.

Digital cartographic data are usually captured by manually digitizing a map or an interpreted photograph or by automatically scanning a map. Both techniques first require manual photointerpretation to describe features of interest. A new approach, bypassing the laborious photointerpretation phase, is being explored using direct digital image analysis. Aerial photographs are scanned and color separated to create raster data. These are then enhanced and classified using several techniques to identify roads and buildings. Finally, the raster representation of these features is refined and vectorized. 11 refs.

Conference Paper↗
USGS1988

Ice gouge processes in the Alaskan Beaufort Sea

A generalized picture of ice gouge characteristics from shallow inshore depths to the outer shelf at about 60 m of water is presented. Data from recent studies show that the size and quantity of gouging increases in an offshore direction to depths of about 45 m where this trend then reverses and the features decrease in size and quantity as the shelf break is approached. Ice gouges are oriented east-west and this suggests that most gouging is caused by ice approaching from the east, possibly driven by the Beaufort Sea gyre. The most intense gouging occurs in the stamukhi zone, between 20 and 40 m of water, and is caused by a high rate of ice keel production owing to shearing forces between mobile and stable sea ice. Inshore of the stamukhi zone, ice gouging still presents a significant hazard but their greatly decreased size and number make it possible to design against this hazard.

Technical Council on Cold Regions Engineering Mono↗
USGS1987

GEOMETRIC PROCESSING OF DIGITAL IMAGES OF THE PLANETS.

New procedures and software have been developed for geometric transformations of images to support digital cartography of the planets. The procedures involve the correction of spacecraft camera orientation of each image with the use of ground control and the transformation of each image to a Sinusoidal Equal-Area map projection with an algorithm which allows the number of transformation calculations to vary as the distortion varies within the image. When the distortion is low in an area of an image, few transformation computations are required, and most pixels can be interpolated. When distortion is extreme, the location of each pixel is computed. Mosaics are made of these images and stored as digital databases.

Photogrammetric Engineering and Remote Sensing↗
USGS1988

Composition of massive sulfide deposits from the sediment-covered floor of Escanaba Trough, Gorda Ridge: implications for depositional processes

Massive sulfide deposits with two distinct compositions are spatially related to volcanic edifices that penetrate up to 500 m of turbiditic sediment in Escanaba Trough (ET), southern Gorda Ridge. The mineralogy, metal content, sulfur isotope composition, and hydrocarbon content of massive sulfides from ET reflect the extensive interaction between underlying turbiditic sediment and hydrothermal fluid. Pyrrhotite-rich sulfide mounds are inferred to have formed under gentle temperature and chemical gradients related to diffuse, low-velocity flow through disrupted sediment near the sediment-capped hills.

Canadian Mineralogist↗
USGS1989

Spectral analysis and filtering techniques in digital spatial data processing

A filter toolbox has been developed at the EROS Data Center, US Geological Survey, for retrieving or removing specified frequency information from two-dimensional digital spatial data. This filter toolbox provides capabilities to compute the power spectrum of a given data and to design various filters in the frequency domain. Three types of filters are available in the toolbox: point filter, line filter, and area filter. Both the point and line filters employ Gaussian-type notch filters, and the area filter includes the capabilities to perform high-pass, band-pass, low-pass, and wedge filtering techniques. These filters are applied for analyzing satellite multispectral scanner data, airborne visible and infrared imaging spectrometer (AVIRIS) data, gravity data, and the digital elevation models (DEM) data. -from Author

Photogrammetric Engineering and Remote Sensing↗
USGS1992

Study of salt transport processes in Delaware Bay

The study described here is a subset of a broader climate-related study, and is focused primarily on salinity intrusion into Delaware Bay and River. Given changes in freshwater discharge into the Delaware River as determined from the larger study, and given probable sea level rise estimates, the purpose here is to calculate the distribution of salinity within Delaware Bay and River. The approach adopted for this study is composed of two parts: an analysis of existing physical data in order to derive a basic understanding of the salt dynamics, and numerical simulation of future conditions based on this analysis. There are two important constraints in the model used: it must resolve the spatial scales important to the salt dynamics, and it must be sufficiently efficient to allow extensive sensitivity studies. This has led to the development of a 3D model that uses harmonic decomposition in time and irregular finite elements in space. All nonlinear terms are retained in the governing equations, including quadratic bottom stress, advection, and wave transport (continuity nonlinearity). These equations are coupled to the advection-diffusion equation for salt so that density gradient forcing is included in the momentum equations. Although this study is still in progress, the model has reproduced sea level variations and the 3D structure of tidal and residual currents very well. In addition, the study has addressed the effects of a 1-meter rise in mean sea level on hydrodynamics of the study area. Current work is focused on salt dynamics.

Conference Paper↗