Effect of discharge on the chlorophyll a distribution in the tidally-influenced Potomac River
J. P. Bennett, J.W. Woodward, D.J. Shultz
1986, Estuaries (9) 250-260
In the tidal Potomac River, high river discharges during the spring are associated with high chlorophylla concentrations in the following in the following summer, assuming that summertime light and temperature conditions are favorable. Spring floods deliver large loads of particulate N and P to the tidal river. This particulate N and...
Seismically induced landslides: current research by the US Geological Survey.
E. L. Harp, R. C. Wilson, D. K. Keefer, G. F. Wieczorek
1986, Geologia Applicata e Idrogeologia (21) 159-173
We have produced a regional seismic slope-stability map and a probabilistic prediction of landslide distribution from a postulated earthquake. For liquefaction-induced landslides, in situ measurements of seismically induced pore-water pressures have been used to establish an elastic model of pore pressure generation. -from Authors...
Tidal reorientation and the fracturing of Jupiter's moon Europa
A. S. McEwen
1986, Nature (321) 49-51
The most striking characteristic of Europa is the network of long linear albedo markings over the surface, suggestive of global-scale tectonic processes. Various explanations for the fractures have been proposed: Freezing and expansion of an early liquid water ocean1, planetary expansion due to dehydration of hydrated silicates2, localization by weak...
Geochemical evaluation of the geothermal resources in the San Marcos region, Guatemala
R.O. Fournier, B.B. Hanshaw
1986, Applied Geochemistry (1) 189-197
The chemical and isotopic compositions of hot springs in the San Marcos region of Guatemala are internally consistent with a hydrologic model in which a deep 240°C reservoir and one or more shallow 195–200°C reservoirs are present. Variations in hot-spring water...
10Be distribution in soils from Merced River terraces, California
M.J. Pavich, L. Brown, J. Harden, J. Klein, R. Middleton
1986, Geochimica et Cosmochimica Acta (50) 1727-1735
The distribution and residence time of cosmogenic 10Be in clay-rich soil horizons is fundamental to understanding and modelling the migration of 10Be on terrestrial sediments and in groundwater solutions. We have analyzed seven profiles of clay-rich soils developed from terrace sediments of the Merced River, California. The terraces and soils of increasing...
Migration of volcanism in the San Francisco volcanic field, Arizona
K. L. Tanaka, E.M. Shoemaker, G. E. Ulrich, E.W. Wolfe
1986, Geological Society of America Bulletin (97) 129-141
The remanent magnetization of volcanic rocks has been determined at 650 sites in the San Francisco volcanic field in the southern part of the Colorado Plateau. The polarity of remanent magnetization—combined with K-Ar age determinations, spatial and petrographic associations, stratigraphic relations, and state of preservation...
Adaptation of the Carter-Tracy water influx calculation to groundwater flow simulation
Kenneth L. Kipp
1986, Water Resources Research (22) 423-428
The Carter-Tracy calculation for water influx is adapted to groundwater flow simulation with additional clarifying explanation not present in the original papers. The Van Everdingen and Hurst aquifer-influence functions for radial flow from an outer aquifer region are employed. This technique, based on convolution of unit-step response functions, offers a...
HYDRODYNAMIC SIMULATION OF THE UPPER POTOMAC ESTUARY.
Raymond W. Schaffranck
1986, Conference Paper
Hydrodynamics of the upper extent of the Potomac Estuary between Indian Head and Morgantown, Md. , are simulated using a two-dimensional model. The model computes water-surface elevations and depth-averaged velocities by numerically integrating finite-difference forms of the equations of mass and momentum conservation using the alternating direction implicit method. The...
Nonlinear-regression groundwater flow modeling of a deep regional aquifer system
Richard L. Cooley, Leonard F. Konikow, Richard L. Naff
1986, Water Resources Research (22) 1759-1778
A nonlinear regression groundwater flow model, based on a Galerkin finite-element discretization, was used to analyze steady state two-dimensional groundwater flow in the areally extensive Madison aquifer in a 75,000 mi2 area of the Northern Great Plains. Regression parameters estimated include intrinsic permeabilities of the main aquifer and separate lineament zones,...
Carbon isotope systematics of a mantle "hotspot": A comparison of Loihi Seamount and MORB glasses
R.A. Exley, D.P. Mattey, D.A. Clague, C.T. Pillinger
1986, Earth and Planetary Science Letters (78) 189-199
The carbon isotope geochemistry of glasses from Loihi Seamount has been compared with that of MORB glasses. Stepped heating shows two carbon components in both sample suites: (1) isotopically light carbon (avg. δ13C = −26.3‰) released < 600°C, ascribed to surficial...
Applications of UThPb isotope systematics to the problems of radioactive waste disposal
J. S. Stuckless
1986, Chemical Geology (55) 215-225
Concentrations of U, Th and Pb, and the isotopic composition of Pb for whole-rock samples of granitoids show: (1) that open-system behavior is nearly universal in the surface and near-surface environment; and (2) that elemental mobility is possible to depths of several hundred meters. Several identified or at least postulated...
Uranium geochemistry in geopressured-geothermal aquifers of the U.S. Gulf Coast
T. F. Kraemer, Y.K. Kharaka
1986, Geochimica et Cosmochimica Acta (50) 1233-1238
Formation water from U.S. Gulf Coast geopressured-geothermal sandstone aquifers has been analyzed to determine the geochemistry of uranium in these systems. Results of chemical analyses and chemical equilibrium modeling indicate the formation waters are in equilibrium with uraninite (UO2) and coffinite (USiO4). The 234U238U">234U238U activity ratios...
Evaluation of gas data from high-temperature fumaroles at Mount St. Helens, 1980-1982
T.M. Gerlach, T. J. Casadevall
1986, Journal of Volcanology and Geothermal Research (28) 107-140
The Mount St. Helens fumarole gases show linear composition trends during periods of noneruptive degassing between September 1980 and October 1981. The trends are characterized by increasing H2O and decreasing CO2 and sulfur. Maximum fumarole temperatures also show a linear decrease during this period. High-temperature fumarole gases collected from the...
Recent patterns of sulfate variability in pristine streams
H.F. Lins
1986, Atmospheric Environment - Part A General Topics (20) 367-375
Systematic modes of spatial and temporal variation in a 13-y record of stream sulfate from a nationwide network of headwater sampling stations are defined using principal components. Based on the undisturbed nature of the sampling network, it is suggested that these modes of stream sulfate variability are analogues for variations...
The origin of fluids in the salt beds of the Delaware Basin, New Mexico and Texas
J. R. O’Neil, C.M. Johnson, L. D. White, E. Roedder
1986, Applied Geochemistry (1) 265-271
Oxygen and hydrogen isotope analyses have been made of (1) brines from several wells in the salt deposits of the Delaware Basin, (2) inclusion fluids in halite crystals from the ERDA No. 9 site, and (3) local ground waters of meteoric...
VISCOPLASTIC FLUID MODEL FOR DEBRIS FLOW ROUTING.
Cheng-lung Chen
1986, Conference Paper
This paper describes how a generalized viscoplastic fluid model, which was developed based on non-Newtonian fluid mechanics, can be successfully applied to routing a debris flow down a channel. The one-dimensional dynamic equations developed for unsteady clear-water flow can be used for debris flow routing if the flow parameters, such...
Obstacles facing the Venus radar mapper - The implications of gestalt formation in stereo-radargrammetry
R.L. Wildey
1986, Earth, Moon and Planets (36) 41-48
The question of adapting to radar images the existing hardware that form topographic maps through stereo-photogrammetric models, is examined in principle. Such hardware utilizes a human/computer hybrid. Although the problem of brightness differentials between corresponding landmarks can be dealt with pseudo-photoclinometrically, the main problem is whether the perspective in a...
A finite element model for tidal and residual circulation
Roy A. Walters
1986, Communications in Numerical Methods in Engineering (2) 393-398
Harmonic decomposition is applied to the shallow water equations, thereby creating a system of equations for the amplitude of the various tidal constituents and for the residual motions. The resulting equations are elliptic in nature, are well posed and in practice are shown to be numerically well-behaved. There are a...
To accrete or not accrete, that is the question
Roland E. von Huene
1986, Geologische Rundschau (75) 1-15
Along modern convergent margins tectonic processes span a spectrum from accretion to erosion. The process of accretion is generally recognized because it leaves a geologic record, whereas the process of erosion is generally hypothetical because it produces a geologic hiatus. Major conditions that determine the dominance of accretion or erosion...
A comparison of several methods for the solution of the inverse problem in two-dimensional steady state groundwater flow modeling
Logan K. Kuiper
1986, Water Resources Research (22) 705-714
Two geostatistical approaches for the estimation of hydraulic conductivity and hydraulic head from hydraulic conductivity and hydraulic head measurements are developed for two-dimensional steady flow with sinks. For both approaches the field of the logarithm of hydraulic conductivity (log-conductivity) is represented as a random field with mean θ1+θ2x+θ3y where xand y denote Cartesian coordinates,...
Simulation of fluid flow and energy transport processes associated with high-level radioactive waste disposal in unsaturated alluvium
David W. Pollock
1986, Water Resources Research (22) 765-775
Many parts of the Great Basin have thick zones of unsaturated alluvium which might be suitable for disposing of high-level radioactive wastes. A mathematical model accounting for the coupled transport of energy, water (vapor and liquid), and dry air was used to analyze one-dimensional, vertical transport above and below an...
RAINFALL-LOSS PARAMETER ESTIMATION FOR ILLINOIS.
Linda S. Weiss, Audrey L. Ishii
1986, Conference Paper
The U. S. Geological Survey is currently conducting an investigation to estimate values of parameters for two rainfall-loss computation methods used in a commonly used flood-hydrograph model. Estimates of six rainfall-loss parameters are required: four for the Exponential Loss-Rate method and two for the Initial and Uniform Loss-Rate method. Multiple...
The modification of an estuary
F.H. Nichols, James E. Cloern, Samuel N. Luoma, D. H. Peterson
1986, Science (231) 567-573
The San Francisco Bay estuary has been rapidly modified by human activity. Diking and filling of most of its wetlands have eliminated habitats for fish and waterfowl; the introduction of exotic species has transformed the composition of its aquatic communities; reduction of freshwater inflow by more than half has changed...
A tubular-coring device for use in biogeochemical sampling of succulent and pulpy plants
W. L. Campbell
1986, Journal of Geochemical Exploration (25) 397-399
A hand-operated, tubular-coring device developed for use in biogeochemical sampling of succulent and pulpy plants is described. The sampler weighs about 500 g (1.1 lb); and if 25 × 175 mm (1 × 7 in) screw-top test tubes are used as...
RECOVERY OF FRESHWATER STORED IN SALINE AQUIFERS IN PENINSULAR FLORIDA.
Michael L. Merritt
1986, Conference Paper
Subsurface freshwater storage has been operationally tested at seven sites in central and south Florida. Injection was into a high chloride water aquifer at six sites, and into a high sulfate water aquifer at the seventh. Recovery efficiency has ranged from 0 to 75 percent in high chloride water aquifers,...
