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G. A. Hearne

Publications and source records attributed to G. A. Hearne.

5 recordsLinked to original sources
USGS1995

Vulnerability of the uppermost ground water to contamination in the greater Denver area, Colorado

Information about vulnerability of ground water to contamination is needed to facilitate ground-water management. Vulnerability of ground water refers to the intrinsic characteristics that determine the sensitivity of the water to being adversely affected by an imposed contaminant load. Within the greater Denver area, vulnerability of the uppermost ground water to contamination from the surface was assessed by considering the intrinsic characteristics included in a method developed by the U.S. Environmental Protection Agency and the National Water Well Association, the DRASTIC method. The seven geohydrologic characteristics considered are: (1) Aquifer media, (2) hydraulic conductivity, (3) unsaturated media, (4) depth to water, (5) recharge, (6) soil media, and (7) land-surface slope. Recharge from precipitation generally is less than 2 inches per year; no effort was made to quantify the variation of recharge throughout the study area. Data for geology, depth to water, soils, and elevation were obtained and processed to produce maps of the other six characteristics. Spatial and attribute data for these maps were stored and processed by geographic-information-system software to produce a map showing vulnerability of the uppermost ground water to contamination from the surface. This report describes the assessment of each geohydrologic characteristic and the 157 vulnerability response units that were delineated within the greater Denver area. These response units are unique with respect to the geohydrologic characteristics considered. The uppermost ground water within each of the vulnerability response units are described in a series of tables, which include qualitative and selected quantitative data and the vulnerability rating assigned for each of the seven geohydrologic characteristics.

Water-Resources Investigations Report↗
USGS1988

Hydrologic analysis of the Rio Grande basin north of Embudo, New Mexico, Colorado and New Mexico

Water yield was estimated for each of the five regions that represent contrasting hydrologic regimes in the 10,400 square miles of the Rio Grande basin above Embudo, New Mexico. Water yield was estimated as 2,800 cubic feet per second for the San Juan Mountains, and 28 cubic feet per second for the Taos Plateau. Evapotranspiration exceeded precipitation by 150 cubic feet per second on the Costilla Plains and 2,400 cubic feet per second on the Alamosa Basin. A three-dimensional model was constructed to represent the aquifer system in the Alamosa Basin. A preliminary analysis concluded that: (1) a seven-layer model representing 3,200 feet of saturated thickness could accurately simulate the behavior of the flow equation; and (2) the 1950 condition was approximately stable and would be a satisfactory initial condition. Reasonable modifications to groundwater withdrawals simulated 1950-79 water-level declines close to measured value. Sensitivity tests indicated that evapotranspiration salvage was the major source, 69 to 82 percent, of groundwater withdrawals. Evapotranspiration salvage was projected to be the source of most withdrawals.

Colorado, New Mexico↗
USGS1987

Ground-water flow and quality near Canon City, Colorado

Water in aquifers that underlie the Lincoln Park area near Canon City, Colorado, contains measurable concentrations of chemical constituents that are similar to those in raffinate (liquid waste) produced by a nearby uranium ore processing mill. The objective of this study was to expand the existing geohydrologic data base by collecting additional geohydrologic and water quality, in order to refine the description of the geohydrologic and geochemical systems in the study area. Geohydrologic data were collected from nine tests wells drilled in the area between the U.S. Soil Conservation Service dam and Lincoln Park. Lithologic and geophysical logs of these wells indicated that the section of Vermejo Formation penetrated consisted of interbedded sandstone and shale. The sandstone beds had a small porosity and small hydraulic conductivity. Groundwater flow from the U.S. Soil Conservation Service dam to Lincoln Park seemed to be along an alluvium-filled channel in the irregular and relatively undescribed topography of the Vermejo Formation subcrop. North of the De Weese Dye Ditch, the alluvium becomes saturated and groundwater generally flows to the northeast. Water samples from 28 sites were collected and analyzed for major ions and trace elements; selected water samples also were analyzed for stable isotopes; samples were collected from wells near the uranium ore processing mill, from privately owned wells in Lincoln Park, and from the test wells drilled in the intervening area. Results from the quality assurance samples indicate that cross-contamination between samples from different wells was avoided and that the data are reliable. Water in the alluvial aquifer underlying Lincoln Park is mainly a calcium bicarbonate type. Small variations in the composition of water in the alluvial aquifer appears to result from a reaction of water leaking from the De Weese Dye Ditch with alluvial material. Upward leakage from underlying aquifers does not seem to be significant in determining the chemical composition of water in the alluvial aquifer. (Author 's abstract)

Water-Resources Investigations Report↗
USGS1980

A computer program for simulating geohydrologic systems in three dimensions

This document is directed toward individuals who wish to use a computer program to simulate ground-water flow in three dimensions. The strongly implicit procedure (SIP) numerical method is used to solve the set of simultaneous equations. New data processing techniques and program input and output options are emphasized. The quifer system to be modeled may be heterogeneous and anisotropic, and may include both artesian and water-table conditions. Systems which consist of well defined alternating layers of highly permeable and poorly permeable material may be represented by a sequence of equations for two dimensional flow in each of the highly permeable units. Boundaries where head or flux is user-specified may be irregularly shaped. The program also allows the user to represent streams as limited-source boundaries when the streamflow is small in relation to the hydraulic stress on the system. The data-processing techniques relating to ' cube ' input and output, to swapping of layers, to restarting of simulation, to free-format NAMELIST input, to the details of each sub-routine 's logic, and to the overlay program structure are discussed. The program is capable of processing large models that might overflow computer memories with conventional programs. Detailed instructions for selecting program options, for initializing the data arrays, for defining ' cube ' output lists and maps, and for plotting hydrographs of calculated and observed heads and/or drawdowns are provided. Output may be restricted to those nodes of particular interest, thereby reducing the volumes of printout for modelers, which may be critical when working at remote terminals. ' Cube ' input commands allow the modeler to set aquifer parameters and initialize the model with very few input records. Appendixes provide instructions to compile the program, definitions and cross-references for program variables, summary of the FLECS structured FORTRAN programming language, listings of the FLECS and FORTRAN source code, and samples of input and output for example simulations. (USGS)

Open-File Report↗