Relating nitrogen sources and aquifer susceptibility to nitrate in shallow ground waters of the United States
B. T. Nolan
2001, Ground Water (39) 290-299
Characteristics of nitrogen loading and aquifer susceptibility to contamination were evaluated to determine their influence on contamination of shallow ground water by nitrate. A set of 13 explanatory variables was derived from these characteristics, and variables that have a significant influence were identified using logistic regression (LR). Multivariate LR models...
Associations of grassland birds with landscape factors in southern Wisconsin
Christine Ribic, D. W. Sample
2001, American Midland Naturalist (146) 105-121
We investigated the association of grassland birds with field- and landscape-level habitat variables in south-central Wisconsin during 1985–1987. Landscape-level variables were measured and digitized at 200, 400 and 800 m from the perimeter of 38 200 m × 100 m strip transects. A mixture of field and landscape variables was...
An analytical solution for transient flow of Bingham viscoplastic materials in rock fractures
B. Amadei, W. Z. Savage
2001, International Journal of Rock Mechanics and Mining Sciences (38) 285-296
We present below an analytical solution to model the one-dimensional transient flow of a Bingham viscoplastic material in a fracture with parallel walls (smooth or rough) that is subjected to an applied pressure gradient. The solution models the acceleration and the deceleration of the material as the pressure gradient changes...
A model for nematode locomotion in soil
H. William Hunt, Diana H. Wall, Nicole DeCrappeo, John S. Brenner
2001, Nematology (3) 705-716
Locomotion of nematodes in soil is important for both practical and theoretical reasons. We constructed a model for rate of locomotion. The first model component is a simple simulation of nematode movement among finite cells by both random and directed behaviours. Optimisation procedures were used to fit the simulation output...
Morphometrics, sexual dimorphism, and growth in the Angonoka tortoise (Geochelone yniphora) of western Madagascar
Lora L. Smith, Miguel Pedrono, Robert M. Dorazio, Jack Bishko
2001, African Journal of Herpetology (50) 9-18
The most recent description of the morphology of the rare endemic Madagascar tortoise,Geochelone yniphora was based on fewer than 20 specimens. We collected morphological data for 200 free‐ranging tortoises from five populations over a four‐year period. Tortoises ranged in size from 43.5 mm carapace length at hatching to a maximum of...
Constants for mercury binding by organic matter isolates from the Florida Everglades
J.M. Benoit, R.P. Mason, C.C. Gilmour, G. R. Aiken
2001, Geochimica et Cosmochimica Acta (65) 4445-4451
Dissolved organic matter (DOM) has been implicated as an important complexing agent for Hg that can affect its mobility and bioavailability in aquatic ecosystems. However, binding constants for natural Hg-DOM complexes are not well known. We employed a competitive ligand approach to estimate conditional stability constants for Hg complexes...
Alien plant invasion in mixed-grass prairie: Effects of vegetation type and anthropogenic disturbance
D.L. Larson, P.J. Anderson, W. Newton
2001, Ecological Applications (11) 128-141
The ability of alien plant species to invade a region depends not only on attributes of the plant, but on characteristics of the habitat being invaded. Here, we examine characteristics that may influence the success of alien plant invasion in mixed-grass prairie at Theodore Roosevelt National Park, in western North...
Hydrothermal element fluxes from Copahue, Argentina: A "beehive" volcano in turmoil
J.C. Varekamp, A.P. Ouimette, S.W. Herman, A. Bermudez, D. Delpino
2001, Geology (29) 1059-1062
Copahue volcano erupted altered rock debris, siliceous dust, pyroclastic sulfur, and rare juvenile fragments between 1992 and 1995, and magmatic eruptions occurred in July– October 2000. Prior to 2000, the Copahue crater lake, acid hot springs, and rivers carried acid brines with compositions that reflected close to congruent rock dissolution....
Rotund versus skinny orogens: Well-nourished or malnourished gold?
R.J. Goldfarb, D.I. Groves, S. Gardoll
2001, Geology (29) 539-542
Orogenic gold vein deposits require a particular conjunction of processes to form and be preserved, and their global distribution can be related to broad-scale, evolving tectonic processes throughout Earth history. A heterogeneous distribution of formation ages for these mineral deposits is marked by two major Precambrian peaks (2800-2555 Ma and...
Permeability reduction in granite under hydrothermal conditions
C.A. Morrow, Diane E. Moore, D.A. Lockner
2001, Journal of Geophysical Research B: Solid Earth (106) 30551-30560
The formation of impermeable fault seals between earthquake events is a feature of many models of earthquake generation, suggesting that earthquake recurrence may depend in part on the rate of permeability reduction of fault zone materials under hydrothermal conditions. In this study, permeability measurements were conducted on intact, fractured, and...
hypoDD-A Program to Compute Double-Difference Hypocenter Locations
Felix Waldhauser
2001, Open-File Report 2001-113
HypoDD is a Fortran computer program package for relocating earthquakes with the double-difference algorithm of Waldhauser and Ellsworth (2000). This document provides a brief introduction into how to run and use the programs ph2dt and hypoDD to compute double-difference (DD) hypocenter locations. It gives a short overview of the DD...
Simulated effects of pumping irrigation wells on ground-water levels in western Saginaw County, Michigan
Christopher J. Hoard, David B. Westjohn
2001, Water-Resources Investigations Report 2001-4227
Success of agriculture in many areas of Michigan relies on withdrawal of large quantities of ground water for irrigation. In some areas of the State, water-level declines associated with large ground-water withdrawals may adversely affect nearby residential wells. Residential wells in several areas of Saginaw County, in Michigan's east-central Lower...
Digital data used to relate nutrient input to water quality in the Chesapeake Bay watershed
John W. Brakebill, Stephen D. Preston, Sarah K. Martucci
2001, Open-File Report 2001-251
Digital data sets compiled by the U.S. Geological Survey were used as input for a collection of Spatially Referenced Regressions On Watershed (SPARROW) attributes for the Chesapeake Bay region including parts of Delaware, Maryland, New York, Pennsylvania, Virginia, West Virginia, and the District of Columbia. These regressions use a nonlinear...
MODFLOW-2000, the U.S. Geological Survey modular ground-water model: User guide to the LMT6 package, the linkage with MT3DMS for multi-species mass transport modeling
Chunmiao Zheng, Mary Catherine Hill, Paul A. Hsieh
2001, Open-File Report 2001-82
MODFLOW-2000, the newest version of MODFLOW, is a computer program that numerically solves the three-dimensional ground-water flow equation for a porous medium using a finite-difference method. MT3DMS, the successor to MT3D, is a computer program for modeling multi-species solute transport in three-dimensional ground-water systems using multiple solution techniques, including the...
Abstracts from "Coastal Marsh Dieback in the Northern Gulf of Mexico: Extent, Causes, Consequences, and Remedies
C. Edward Proffitt, Tammy Michelle Charron
Robert E. Stewart Jr., editor(s)
2001, Information and Technology Report 2001-0003
In the spring of 2000, scientists discovered a new and unprecedented loss of salt marsh vegetation in coastal Louisiana and other areas along the northern coast of the Gulf of Mexico. This dieback of salt marsh vegetation, sometimes called the brown marsh phenomenon', primarily involved the rapid browning and dieback...
Geochemistry and origins of mineralized waters in the Floridan aquifer system, northeastern Florida
G. G. Phelps
2001, Water-Resources Investigations Report 2001-4112
Increases in chloride concentration have been observed in water from numerous wells tapping the Floridan aquifer system in northeastern Florida. Although most increases have been in the eastern part of Duval County, Florida, no spatial pattern in elevated chloride concentrations is discernible. Possible sources of the mineralized water include modern...
Ground-water flow in the shallow aquifer system at the Naval Weapons Station Yorktown, Virginia
Barry S. Smith
2001, Water-Resources Investigations Report 2000-4077
The Environmental Directorate of the Naval Weapons Station Yorktown, Virginia, is concerned about possible contamination of ground water at the Station. Ground water at the Station flows through a shallow system of layered aquifers and leaky confining units. The units of the shallow aquifer system are the Columbia aquifer, the...
Map Showing Susceptibility to Earthquake-Induced Landsliding, San Juan Metropolitan Area, Puerto Rico
Marilyn Santiago, Matthew C. Larsen
2001, Open-File Report 2001-39
Analysis of slope angle and rock type using a geographic information system indicates that about 68 percent of the San Juan metropolitan area has low to no susceptibility to earthquake-induced landslides. This is at least partly due to the fact that 45 percent of the San Juan metropolitan area is...
Use of a watershed-modeling approach to assess hydrologic effects of urbanization, North Fork Pheasant Branch basin near Middleton, Wisconsin
Jeffrey J. Steuer, R. J. Hunt
2001, Water-Resources Investigations Report 2001-4113
The North Fork Pheasant Branch Basin in Dane County, Wisconsin is expected to undergo development. There are concerns that development will adversely affect water resources with increased flood peaks, increased runoff volumes, and increased pollutant loads. To provide a scientific basis for evaluating the hydrologic system response to development the...
Simulation of flow and evaluation of bridge scour at Horse Island Chute Bridge near Chester, Illinois
Richard J. Huizinga, Paul H. Rydlund Jr.
2001, Water-Resources Investigations Report 2001-4176
The evaluation of scour at bridges throughout the State of Missouri has been ongoing since 1991, and most of these evaluations have used one-dimensional hydraulic analysis and application of conventional scour depth equations. Occasionally, the conditions of a site dictate that a more thorough hydraulic assessment is required. To provide...
Simulations of flooding on the Tennessee River in the vicinity of U.S. Highway 231 near Huntsville, Alabama
T. Scott Hedgecock
2001, Water-Resources Investigations Report 2001-4114
A two-dimensional finite-element surface-water model was used to study the effects of proposed modifications to the U.S. Highway 231 corridor on water-surface elevations and flow distributions during flooding in the Tennessee River Basin south of Huntsville, Madison County, Alabama. Flooding was first simulated for the March 19, 1973, flood for...
Gore Creek watershed, Colorado — Assessment of historical and current water quantity, water quality, and aquatic ecology, 1968–98
Kirby H. Wynn, Nancy J. Bauch, Nancy E. Driver
2001, Water-Resources Investigations Report 99-4270
The historical and current (1998) water-quantity, water-quality, and aquatic-ecology conditions in the Gore Creek watershed are described as part of a study by the U.S. Geological Survey, done in cooperation with the Town of Vail, the Eagle River Water and Sanitation District, and the Upper Eagle Regional Water Authority. Interpretation...
An alternative regionalization scheme for defining nutrient criteria for rivers and streams
Dale M. Robertson, David A. Saad, Ann M. Wieben
2001, Water-Resources Investigations Report 2001-4073
To protect and manage rivers and streams (hereafter, collectively referred to as streams) in the United States, the U.S. Environmental Protection Agency (USEPA) is establishing regionally based nutrient criteria that reflect the natural variability in water quality. As a basic approach to establish these criteria, the USEPA has divided the...
Preliminary evaluation of the importance of existing hydraulic-head observation locations to advective-transport predictions, Death Valley regional flow system, California and Nevada
Mary C. Hill, D. Matthew Ely, Claire R. Tiedeman, Grady M. O’Brien, Frank A. D’Agnese, Claudia C. Faunt
2001, Water-Resources Investigations Report 2000-4282
When a model is calibrated by nonlinear regression, calculated diagnostic statistics and measures of uncertainty provide a wealth of information about many aspects of the system. This report presents a method of ranking the likely importance of existing observation locations using measures of prediction uncertainty. It is suggested that continued...
Aquifer-characteristics data for West Virginia
Mark D. Kozar, Melvin V. Mathes
2001, Water-Resources Investigations Report 2001-4036
Specific-capacity, storage-coefficient, and specific-yield data for wells in West Virginia were compiled to provide a data set from which transmissivity could be estimated. This data can be used for analytical and mathematical groundwater flow modeling. Analysis of available storage-coefficient and (or) specific-yield data indicates the Ohio River alluvial aquifer has...
