On the formation of granulites
S.R. Bohlen
1991, Journal of Metamorphic Geology (9) 223-229
The tectonic settings for the formation and evolution of regional granulite terranes and the lowermost continental crust can be deduced from pressure–temperature–time (P–T–time) paths and constrained by petrological and geophysical considerations.P–T conditions deduced for regional granulites require transient, average geothermal gradients of greater than 35°C km−1, implying minimum heat flow in...
The southeastern Illinois earthquake of 10 June 1987: The later aftershocks
C.J. Langer, G. A. Bollinger
1991, Bulletin of the Seismological Society of America (81) 423-445
The 10 June 1987 southeastern Illinois earthquake (mbLg = 5.2) was the seventh in a series of moderate magnitude (≧ 4.5) MMI VII shocks to occur in the Wabash Valley seismic zone of southeastern Illinois and southwestern Indiana since 1891. Located about 200 km east of St. Louis, Missouri, the...
Estimation of suspended-sediment rating curves and mean suspended-sediment loads
Charles G. Crawford
1991, Journal of Hydrology (129) 331-348
Suspended-sediment loads are often estimated from an empirical relation between suspended-sediment load (L) and streamflow (S). This relation is usually defined as a power function, L = aSh, and is referred to as a suspended-sediment rating curve. This function can be formulated as either a linear or non-linear model to...
Coupled surface-water and ground-water model
Eric D. Swain, Eliezer J. Wexler
1991, Conference Paper
In areas with dynamic and hydraulically well connected ground-water and surface-water systems, it is desirable that stream-aquifer interaction be simulated with models of equal sophistication and accuracy. Accordingly, a new, coupled ground-water and surface-water model was developed by combining the U.S. Geological Survey models MODFLOW and BRANCH. MODFLOW is the...
Crustal resistivity structure from magnetotelluric soundings in the Colorado Plateau-Basin and Range provinces, central and western Arizona
D. P. Klein
1991, Journal of Geophysical Research (96) 12313-12331
Resistivity structure to about 25 km depth is defined from two-dimensional modeling of 29 magnetotelluric (MT) soundings (0.002–5 Hz) that traverse 280 km of the southwestern Colorado Plateau, transition zone, and Basin and Range provinces in Arizona. From the surface to 5 km depth, the MT...
Capture zones for simple aquifers
Carl D. McElwee
1991, Ground Water (29) 587-590
Abstract. The protection and cleanup of aquifers is a matter of high priority for all states and the federal government. One concept that is receiving increased attention is that of wellhead protection. Capture zones showing the area influenced by a well within a certain time are...
Interfacing data analysis and numerical modeling for tidal hydrodynamic phenomena
R. T. Cheng, J.R. Burau, J. W. Gartner
B. B. Parker, editor(s)
1991, Book chapter, Tidal Hydrodynamics
No abstract available....
Importance of hydrologic data for interpreting wetland maps and assessing wetland loss and mitigation
V. Carter
1991, Biological Report - US Fish & Wildlife Service (90) 79-85
The US Geological Survey collects and disseminates, in written and digital formats, groundwater and surface-water information related to the tidal and nontidal wetlands of the United States. This information includes quantity, quality, and availability of groundwater and surface water; groundwater and surface-water interactions (recharge-discharge); groundwater flow; and the basic surface-water...
Origin of late dolomite cement by CO2-saturated deep basin brines: evidence from the Ozark region, central United States
D. L. Leach, G.S. Plumlee, A. H. Hofstra, G. P. Landis, E. L. Rowan, J.G. Viets
1991, Geology (19) 348-351
Studies of fluid inclusions in regionally extensive late dolomite cement (LDC) throughout the Ozark region show that CO2 effervescence was widespread during dolomite precipitation. On the basis of quantitative analyses of inclusion fluids, reaction-path modeling shows that LDC with trace amounts of sulfides can...
Pre-exploitation state of the Ahuachapán geothermal field, El Salvador
Z. Aunzo, C. Laky, B. Steingrimsson, G.S. Bodvarsson, M.J. Lippmann, A.H. Truesdell, C. Escobar, A. Quintanilla, G. Cuellar
1991, Geothermics (20) 1-22
The lithology and structural features of the Ahuachapán geothermal area and their impact on the movement of cold and hot fluids within the system are described, as well as the development and evaluation of the natural state model of the field. Four major lithologic units are present in Ahuachapán and...
Exploration drilling and reservoir model of the Platanares geothermal system, Honduras, Central America
F. Goff, S.J. Goff, S. Kelkar, L. Shevenell, A.H. Truesdell, J. Musgrave, H. Rufenacht, W. Flores
1991, Journal of Volcanology and Geothermal Research (45) 101-123
Results of drilling, logging, and testing of three exploration core holes, combined with results of geologic and hydrogeochemical investigations, have been used to present a reservoir model of the Platanares geothermal system, Honduras. Geothermal fluids circulate at depths ??? 1.5 km in a region of active tectonism devoid of Quaternary...
Sensitivity analysis of a ground-water-flow model
Lynn J. Torak
Lennon Gerard P.Rouhani Shahrokh, editor(s)
1991, Conference Paper, Symposium on Ground Water
A sensitivity analysis was performed on 18 hydrological factors affecting steady-state groundwater flow in the Upper Floridan aquifer near Albany, southwestern Georgia. Computations were based on a calibrated, two-dimensional, finite-element digital model of the stream-aquifer system and the corresponding data inputs. Flow-system sensitivity was analyzed by computing water-level residuals obtained...
Improved selenium recovery from tissue with modified sample decomposition
W. G. Brumbaugh, M.J. Walther
1991, Journal of the Association of Official Analytical Chemists (74) 570-571
The present paper describes a simple modification of a recently reported decomposition method for determination of selenium in biological tissue by hydride generation atomic absorption. The modified method yielded slightly higher selenium recoveries (3-4%) for selected reference tissues and fish tissue spiked with selenomethionine....
Clarifications and corrections of the dates of issue of some publications containing descriptions of North American birds
M. Ralph Browning, Burt L. Monroe Jr.
1991, Archives of Natural History (18) 381-405
The date of issue of a work containing a new scientific name determines the date the name is available and, therefore, the priority of the name with respect to other applied to the same taxon. Differences between the dates printed in publications and the actual dates of issues often...
Hydrogeology and water quality of glacial-drift aquifers in the Bemidji-Bagley area, Beltrami, Clearwater, Cass, and Hubbard Counties, Minnesota
J. R. Stark, J. P. Busch, M. H. Deters
1991, Water-Resources Investigations Report 89-4136
Unconfined and the upper confined aquifers in glacial drift are the primary sources of water in a 1,600 square-mile area including parts of Beltrami, Cass, Clearwater, and Hubbard Counties, Minnesota. The unconfineddrift aquifer consists of coarse sand and gravel in the center of the study area. The total area underlain...
A method to estimate canal leakage to the Biscayne Aquifer, Dade County, Florida
D.A. Chin
1990, Water-Resources Investigations Report 90-4135
The leakage characteristics of channels that partially penetrate the Biscayne aquifer and have reduced bed permeability were studied. Leakage characteristics were described in terms of a reach transmissivity-defined as the volume flow rate out of the channel per unit length of the channel per unit drawdown, where drawdown is defined...
Solving groundwater flow problems by conjugate-gradient methods and the strongly implicit procedure
Mary C. Hill
1990, Water Resources Research (26) 1961-1969
The performance of the preconditioned conjugate-gradient method with three preconditioners is compared with the strongly implicit procedure (SIP) using a scalar computer. The preconditioners considered are the incomplete Cholesky (ICCG) and the modified incomplete Cholesky (MICCG), which require the same computer storage as SIP as programmed for a problem with...
Ground-water resources and simulated effects of withdrawals in the East Shore area of Great Salt Lake, Utah
David W. Clark, Cynthia L. Appel, Patrick M. Lambert, Robert L. Puryear
1990, Technical Publication 93
The ground-water resources in the East Shore area of Great Salt Lake, Utah, were studied to better define the ground-water system; to document changes in ground-water levels, quality, and storage; and to simulate effects of an increase in ground-water withdrawals. The East Shore aquifer system is in basin-fill deposits, and...
Base of moderately saline ground water in San Juan County, Utah
Lewis Howells
1990, Technical Publication 94
The base of moderately saline ground water (water that contains from 3,000 to 10,000 milligrams per liter of dissolved solids) was delineated for San Juan County, Utah, based on water-quality data and on formation-water resistivities determined from geophysical well logs using the resistivity-porosity, spontaneous-potential, and resistivity-ratio methods. These data and...
Lava domes modeled as brittle shells that enclose pressurized magma, with application to Mount St. Helens
R.M. Iverson
J.H. Fink, editor(s)
1990, Book chapter, Language flows and domes
Estimating groundwater exchange with lakes: 1. The stable isotope mass balance method
David P. Krabbenhoft, Carl J. Bowser, Mary P. Anderson, John W. Valley
1990, Water Resources Research (26) 2445-2453
Groundwater inflow and outflow contributions to the hydrologic budget of lakes can be determined using a stable isotope (18O/16O) mass balance method. The stable isotope method provides a way of integrating the spatial and temporal complexities of the flow field around a lake, thereby offering an appealing alternative to the...
Estimating groundwater exchange with lakes: 2. Calibration of a three-dimensional, solute transport model to a stable isotope plume
David P. Krabbenhoft, Mary P. Anderson, Carl J. Bowser
1990, Water Resources Research (26) 2455-2462
A three-dimensional groundwater flow and solute transport model was calibrated to a plume of water described by measurements of δ18O and used to calculate groundwater inflow and outflow rates at a lake in northern Wisconsin. The flow model was calibrated to observed hydraulic gradients and estimated recharge rates. Calibration of...
An efficient deterministic-probabilistic approach to modeling regional groundwater flow: 1. Theory
Chung-Cheng Yen, Gary L. Guymon
1990, Water Resources Research (26) 1559-1567
An efficient probabilistic model is developed and cascaded with a deterministic model for predicting water table elevations in regional aquifers. The objective is to quantify model uncertainty where precise estimates of water table elevations may be required. The probabilistic model is based on the two-point probability method which only requires...
An efficient deterministic-probabilistic approach to modeling regional groundwater flow: 2. Application to Owens Valley, California
Gary L. Guymon, Chung-Cheng Yen
1990, Water Resources Research (26) 1569-1581
The applicability of a deterministic-probabilistic model for predicting water tables in southern Owens Valley, California, is evaluated. The model is based on a two-layer deterministic model that is cascaded with a two-point probability model. To reduce the potentially large number of uncertain variables in the deterministic model, lumping of uncertain...
Land use and land cover digital data from 1:250,000- and 1:100,000- scale maps
Water Resources Division, U.S. Geological Survey
1990, Data Users Guide 4
The Earth Science Information Centers (ESIC) distribute digital cartographic/geographic data files produced by the U.S. Geological Survey (USGS) as part of the National Mapping Program. The data files are grouped into four basic types. The first type, called a Digital Line Graph (DLG), is line map information in digital form....
