A comparison of the IGBP DISCover and University of Maryland 1 km global land cover products
M.C. Hansen, B. Reed
2000, International Journal of Remote Sensing (21) 1365-1373
Two global 1 km land cover data sets derived from 1992-1993 Advanced Very High Resolution Radiometer (AVHRR) data are currently available, the International Geosphere-Biosphere Programme Data and Information System (IGBP-DIS) DISCover and the University of Maryland (UMd) 1 km land cover maps. This paper makes a preliminary comparison of the...
Digital elevation models derived from small format lunar images
Mark R. Rosiek, Randolph L. Kirk, Elpitha Howington-Kraus
2000, Conference Paper, ASPRS 2000 proceedings : start the 21st century : launching the geospatial information age
No abstract available....
Nutrients discharged to the Mississippi River from eastern Iowa watersheds, 1996-1997
Kent Becher, Douglas J. Schnoebelen, Kimberlee K. Akers
2000, Journal of the American Water Resources Association (36) 161-173
The introduction of nutrients from chemical fertilizer, animal manure, wastewater, and atmospheric deposition to the eastern Iowa environment creates a large potential for nutrient transport in watersheds. Agriculture constitutes 93 percent of all land use in eastern Iowa. As part of the U.S. Geological Survey National Water Quality Assessment Program,...
Basin level statistical properties of topographic index for North America
Praveen Kumar, Kristine L. Verdin, Susan K. Greenlee
2000, Advances in Water Resources (23) 571-578
For land–atmosphere interaction studies several Topmodel based land-surface schemes have been proposed. For the implementation of such models over the continental (and global) scales, statistical properties of the topographic indices are derived using GTOPO30 (30-arc-second; 1 km resolution) DEM data for North America. River basins and drainage...
Chamber measurement of surface-atmosphere trace gas exchange: Numerical evaluation of dependence on soil interfacial layer, and source/sink products
G.L. Hutchinson, G.P. Livingston, R. W. Healy, Robert G. Striegl
2000, Journal of Geophysical Research D: Atmospheres (105) 8865-8875
We employed a three-dimensional finite difference gas diffusion model to simulate the performance of chambers used to measure surface-atmosphere tace gas exchange. We found that systematic errors often result from conventional chamber design and deployment protocols, as well as key assumptions behind the estimation of trace gas exchange rates...
Age and Pb-Sr-Nd isotopic systematics of plutonic rocks from the Green Mountain magmatic arc, southeastern Wyoming: Isotopic characterization of a Paleoproterozoic island arc system
Wayne R. Premo, R. R. Loucks
2000, Rocky Mountain Geology (35) 51-70
Three new U-Pb zircon ages and the Pb-Sr-Nd isotopic systematics of 24 whole-rock samples from mainly plutonic rocks of the Sierra Madre and Medicine Bow Mountains near the Colorado-Wyoming border help establish the Green Mountain magmatic arc as a Paleoproterozoic, variably eroded, island arc terrane. The Green Mountain magmatic arc,...
Geomorphometry-Diversity in quantitative surface analysis
Richard J. Pike
2000, Progress in Physical Geography: Earth and Environment (24) 1-20
A widening variety of applications is diversifying geomorphometry (digital terrain modelling), the quantitative study of topography. An amalgam of earth science, mathematics, engineering and computer science, the discipline has been revolutionized by the computer manipulation of gridded terrain heights, or digital elevation models (DEMs). Its rapid expansion continues. This article...
Monitoring beach morphology changes using small-format aerial photography and digital softcopy photogrammetry
Cheryl Hapke, Bruce M. Richmond
2000, Environmental Geosciences (7) 32-37
Current methods of monitoring beach morphology changes commonly involve the establishment of Global Positioning System profiles that are surveyed on a regular basis. Although this method produces precise measurements of coastal topography, it is costly in time and effort and may result in large data gaps between profiles. Much of...
Trends in surface-water quality during implementation of best-management practices in Mill Creek and Muddy Run Basins, Lancaster County, Pennsylvania
Edward H. Koerkle
2000, Fact Sheet 168-99
Analyses of water samples collected over a 5-year period (1993-98) in the Mill Creek and Muddy Run Basins during implementation of agricultural best-management practices (BMP’s) indicate statistically significant trends in the concentrations of several nutrient species and in nonfilterable residue (suspended solids). The strongest trends identified were those indicated by...
Using OTIS to model solute transport in streams and rivers
Robert L. Runkel
2000, Fact Sheet 138-99
Solute transport in streams and rivers is governed by a suite of hydrologic and geochemical processes. Knowledge of these processes is needed when assessing the fate of contaminants that are released into surface waters. The study of solute fate and transport often is aided by solute transport models that mathematically...
Water levels and ground-water discharge, regional aquifer system of the midwestern Basins and Arches Region, in parts of Indiana, Ohio, Illinois, and Michigan
Sandra M. Eberts
2000, Hydrologic Atlas 725
Aquifers in Quaternary glacial deposits and the underlying Silurian and Devonian carbonate bedrock in parts of Indiana, Ohio, Illinois, and Michigan compose the regional aquifer system under investigation as part of the Midwestern Basins and Arches Regional Aquifer System Analysis (Midwestern Basins and Arches—RASA) project of the U.S. Geological Survey...
Compositional analyses of small lunar pyroclastic deposits using Clementine multispectral data
Lisa R. Gaddis, Bernard Ray Hawke, Mark S. Robinson, Cassandra Coombs
2000, Journal of Geophysical Research E: Planets (105) 4245-4262
Clementine ultraviolet-visible (UVVIS) data are used to examine the compositions of 18 pyroclastic deposits (15 small, three large) at 13 sites on the Moon. Compositional variations among pyroclastic deposits largely result from differing amounts of new basaltic (or juvenile) material and reworked local material entrained in their ejecta upon eruption....
Evaluation of seismic slope-performance models using a regional case study
Scott B. Miles, David K. Keefer
2000, Environmental and Engineering Geoscience (6) 25-39
This paper compares four permanent displacement models based on Newmark's sliding-block analogy for assessing regional seismic slope-performance. The models vary primarily by the ground motion descriptor used to correlate with Newmark displacement. The first uses peak ground-acceleration (PGA). The second uses PGA but normalizes displacements by predominant period and equivalent...
National land-cover pattern data
Kurt H. Riitters, James D. Wickham, James Vogelmann, K. Bruce Jones
2000, Ecology (81) 604
Land cover and its spatial patterns are key ingredients in ecological studies that consider large regions and the impacts of human activities. Because land-cover maps show only cover types and their locations, further processing is needed to extract pattern information and to characterize its spatial variability. We are producing a...
Development of a pore network simulation model to study nonaqueous phase liquid dissolution
Leslie A. Dillard, Martin J. Blunt
2000, Water Resources Research (36) 439-454
A pore network simulation model was developed to investigate the fundamental physics of nonequilibrium nonaqueous phase liquid (NAPL) dissolution. The network model is a lattice of cubic chambers and rectangular tubes that represent pore bodies and pore throats, respectively. Experimental data obtained by Powers [1992] were used to develop and validate the...
Formation of submarine flat-topped volcanic cones in Hawai'i
D. Clague, James G. Moore, J.R. Reynolds
2000, Bulletin of Volcanology (62) 214-233
High-resolution bathymetric mapping has shown that submarine flat-topped volcanic cones, morphologically similar to ones on the deep sea floor and near mid-ocean ridges, are common on or near submarine rift zones of Kilauea, Kohala (or Mauna Kea), Mahukona, and Haleakala volcanoes. Four flat-topped cones on Kohala were explored and sampled...
Effort explores 130 Million years of Antarctic paleoenvironment
Yngve Kristoffersen, I.D. Goodwin, Alan K. Cooper
2000, Eos, Transactions, American Geophysical Union (81) 36-37
Antarctic climate history has been dominated by events and turning points with causes that are poorly understood. To fill the gaps in our knowledges new effort is underway in the international geologic community to acquire and coordinate the circum‐Antarctic geologic data needed to derive and model paleoenvironments of the past...
Changes in North Atlantic deep-sea temperature during climatic fluctuations of the last 25,000 years based on ostracode Mg/Ca ratios
Gary S. Dwyer, Thomas M. Cronin, Paul A. Baker, Julio Rodriguez-Lazaro
2000, Geochemistry, Geophysics, Geosystems (1)
We reconstructed three time series of last glacial-to-present deep-sea temperature from deep and intermediate water sediment cores from the western North Atlantic using Mg/Ca ratios of benthic ostracode shells. Although the Mg/Ca data show considerable variability (“scatter”) that is common to single-shell chemical analyses, comparisons between cores, between core top...
Self-ordering and complexity in epizonal mineral deposits
Richard W. Henley, Byron R. Berger
2000, Annual Review of Earth and Planetary Sciences (28) 669-719
Epizonal base and precious metal deposits makeup a range of familiar deposit styles including porphyry copper-gold, epithermal veins and stockworks, carbonate-replacement deposits, and polymetallic volcanic rock-hosted (VHMS) deposits. They occur along convergent plate margins and are invariably associated directly with active faults and volcanism. They are complex in form, variable...
Stable isotope evolution and paleolimnology of ancient Lake Creede
Robert O. Rye, Philip M. Bethke, David B. Finkelstein
2000, GSA Special Papers (346) 233-265
The lacustrine carbonate and travertine (tufa) deposits of ancient Lake Creede preserve a remarkable record of the isotopic evolution of the lake. That record indicates that the δ18O of the lake water, and by analogy its salinity, evolved through evaporation. Limited and less reliable data on hydrous minerals and fluid...
Trace metal-rich Quaternary hydrothermal manganese oxide and barite deposit, Milos Island, Greece
J.R. Hein, G. Stamatakis, J.S. Dowling
2000, Applied Earth Sciences (109) 67-76
The Cape Vani Mn oxide and barite deposit on Milos Island offers an excellent opportunity to study the three-dimensional characteristics of a shallow-water hydrothermal system. Milos Island is part of the active Aegean volcanic arc. A 1 km long basin located between two dacitic domes in northwest Milos is filled...
Streamflow changes in the Sierra Nevada, California, simulated using a statistically downscaled general circulation model scenario of climate change
Robert L. Wilby, Michael D. Dettinger
2000, Book chapter, Linking climate change to land surface change
Simulations of future climate using general circulation models (GCMs) suggest that rising concentrations of greenhouse gases may have significant consequences for the global climate. Of less certainty is the extent to which regional scale (i.e., sub-GCM grid) environmental processes will be affected. In this chapter, a range of downscaling techniques...
Hydrologic and geologic characteristics of the Yucca Mountain site relevant to the performance of a potential repository
R.A. Levich, R.M. Linden, R.L. Patterson, J. S. Stuckless
2000, GSA Field Guides (2) 383-414
Yucca Mountain, located ~100 mi northwest of Las Vegas, Nevada, has been designated by Congress as a site to be characterized for a potential mined geologic repository for high-level radioactive waste. This field trip will examine the regional geologic and hydrologic setting for Yucca Mountain, as well as specific results...
Can contaminant transport models predict breakthrough?
Wei-Shyuan Peng, Duane R. Hampton, Leonard F. Konikow, Kiran Kambham, Jeffery J. Benegar
2000, Groundwater Monitoring & Remediation (20) 104-113
A solute breakthrough curve measured during a two-well tracer test was successfully predicted in 1986 using specialized contaminant transport models. Water was injected into a confined, unconsolidated sand aquifer and pumped out 125 feet (38.3 m) away at the same steady rate. The injected water was spiked with bromide for...
Late Cenozoic crustal extension and magmatism, southern Death Valley region, California
J.P. Calzia, O.T. Ramo
2000, GSA Field Guides (2) 135-164
The late Cenozoic geologic history of the southern Death Valley region is characterized by coeval crustal extension and magamatism. Crustal extension is accommodated by numerous listric and planar normal faults as well as right- and left-lateral strike slip faults. The normal faults sip 30°-50° near the surface and flatten and...
