USGS Science⌕ Search

Geology topics

E. R. Banta

Publications and source records attributed to E. R. Banta.

11 recordsLinked to original sources
USGS2008

Building model analysis applications with the Joint Universal Parameter IdenTification and Evaluation of Reliability (JUPITER) API

The open-source, public domain JUPITER (Joint Universal Parameter IdenTification and Evaluation of Reliability) API (Application Programming Interface) provides conventions and Fortran-90 modules to develop applications (computer programs) for analyzing process models. The input and output conventions allow application users to access various applications and the analysis methods they embody with a minimum of time and effort. Process models simulate, for example, physical, chemical, and (or) biological systems of interest using phenomenological, theoretical, or heuristic approaches. The types of model analyses supported by the JUPITER API include, but are not limited to, sensitivity analysis, data needs assessment, calibration, uncertainty analysis, model discrimination, and optimization. The advantages provided by the JUPITER API for users and programmers allow for rapid programming and testing of new ideas. Application-specific coding can be in languages other than the Fortran-90 of the API. This article briefly describes the capabilities and utility of the JUPITER API, lists existing applications, and uses UCODE_2005 as an example.

Computers & Geosciences↗
USGS2000

MODFLOW-2000, the U.S. Geological Survey modular ground-water model; user guide to the observation, sensitivity, and parameter-estimation processes and three post-processing programs

This report documents the Observation, Sensitivity, and Parameter-Estimation Processes of the ground-water modeling computer program MODFLOW-2000. The Observation Process generates model-calculated values for comparison with measured, or observed, quantities. A variety of statistics is calculated to quantify this comparison, including a weighted least-squares objective function. In addition, a number of files are produced that can be used to compare the values graphically. The Sensitivity Process calculates the sensitivity of hydraulic heads throughout the model with respect to specified parameters using the accurate sensitivity-equation method. These are called grid sensitivities. If the Observation Process is active, it uses the grid sensitivities to calculate sensitivities for the simulated values associated with the observations. These are called observation sensitivities. Observation sensitivities are used to calculate a number of statistics that can be used (1) to diagnose inadequate data, (2) to identify parameters that probably cannot be estimated by regression using the available observations, and (3) to evaluate the utility of proposed new data. The Parameter-Estimation Process uses a modified Gauss-Newton method to adjust values of user-selected input parameters in an iterative procedure to minimize the value of the weighted least-squares objective function. Statistics produced by the Parameter-Estimation Process can be used to evaluate estimated parameter values; statistics produced by the Observation Process and post-processing program RESAN-2000 can be used to evaluate how accurately the model represents the actual processes; statistics produced by post-processing program YCINT-2000 can be used to quantify the uncertainty of model simulated values. Parameters are defined in the Ground-Water Flow Process input files and can be used to calculate most model inputs, such as: for explicitly defined model layers, horizontal hydraulic conductivity, horizontal anisotropy, vertical hydraulic conductivity or vertical anisotropy, specific storage, and specific yield; and, for implicitly represented layers, vertical hydraulic conductivity. In addition, parameters can be defined to calculate the hydraulic conductance of the River, General-Head Boundary, and Drain Packages; areal recharge rates of the Recharge Package; maximum evapotranspiration of the Evapotranspiration Package; pumpage or the rate of flow at defined-flux boundaries of the Well Package; and the hydraulic head at constant-head boundaries. The spatial variation of model inputs produced using defined parameters is very flexible, including interpolated distributions that require the summation of contributions from different parameters. Observations can include measured hydraulic heads or temporal changes in hydraulic heads, measured gains and losses along head-dependent boundaries (such as streams), flows through constant-head boundaries, and advective transport through the system, which generally would be inferred from measured concentrations. MODFLOW-2000 is intended for use on any computer operating system. The program consists of algorithms programmed in Fortran 90, which efficiently performs numerical calculations and is fully compatible with the newer Fortran 95. The code is easily modified to be compatible with FORTRAN 77. Coordination for multiple processors is accommodated using Message Passing Interface (MPI) commands. The program is designed in a modular fashion that is intended to support inclusion of new capabilities.

Open-File Report↗
USGS1997

Use of 234U and 238U isotopes to evaluate contamination of near-surface groundwater with uranium-mill effluent: A case study in south-central Colorado, U.S.A.

The 234U/238U alpha activity ratio (AR) was determined in 47 samples of variably uraniferous groundwater from the vicinity of a uranium mill near Canon City, Colorado. The results illustrate that uranium isotopes can be used to determine the distribution of uranium contamination in groundwater and to indicate processes such as mixing and chemical precipitation that affect uranium concentrations. Highly to moderately contaminated groundwater samples collected from the mill site and land immediately downgradient from the mill site contain more than 100 ??g/l of dissolved uranium and typically have AR values in the narrow range of 1.0-1.06. Other samples from the shallow alluvial aquifer farther downgradient from the mill contain 10-100 ??g/1 uranium and plot along a broad trend of increasing AR (1.06-1.46) with decreasing uranium concentration. The results are consistent with mixing of liquid mill waste (AR ??? 1.0) with alluvial groundwater of small, but variable, uranium concentrations and AR of 1.31.5. In the alluvial aquifer, the spatial distribution of wells with AR values less than 1.3 is consistent with previous estimates of the probable distribution of contamination, based on water chemistry and hydrology. Wells more distant from the area of probable contamination have AR values that are consistently greater than 1.3 and are indicative of little or no contamination. The methodology of this study can be extended usefully to similar sites of uranium mining, milling, or processing provided that local geohydrologic settings promote uranium mobility and that introduced uranium contamination is isotopically distinct from that of local groundwater.

Environmental Geology↗
USGS1993

Data from core analyses, aquifer testing, and geophysical logging of Denver Basin bedrock aquifers at Castle Pines, Colorado

This report contains data pertaining to the geologic and hydrologic characteristics of the bedrock aquifers of the Denver basin at a site near Castle Pines, Colorado. Data consist of a lithologic- description of about 2,400 ft of drill core and laboratory determinations of mineralogy, grain size, bulk and grain density, porosity, specific yield, and specific retention for selected core samples. Water-level data, atmospheric-pressure measurements, aquifer-compression measurements, and borehole geophysical logs also are included.

Open-File Report↗
USGS1993

Water resources of Washakie County, Wyoming

Data on the surface- and ground-water resources are complied to summarize the water resources of Washakie County. This study, prepared in cooperation with the Wyoming State Engineer, is one in a series investigating the water resources of Wyoming counties . The three principal types of streams in the county are perennial, intermittent, and ephemeral. Perennial streams have continuous streamflows, and high streamflows are associated with snowmelt runoff; low streamflows usually occur in the winter months when the snowpack is frozen and ground-water discharge is at its smallest rate. Intermittent and ephemeral streams are characterized by periods of no flow, and high streamflows are associated with snowmelt or thunderstorms. The principal aquifers are as follows: alluvium of Quaternary age, Willwood Formation of Tertiary age, Fort Union Formation of Tertiary age, and the formations of primarily Paleozoic age--Goose Egg Formation, Tensleep Sandstone, Madison Limestone, Bighorn Dolomite, and Flathead Sandstone. Reported yields from wells completed in the alluvium ranged from 10 to 40 gallons per minute, and reported yields from wells completed in the Willwood Formation ranged from 1 to 28 gallons per minute. Yields as large as 2,500 gallons per minute are reported from wells completed in the Madison Limestone, Bighorn Dolomite, and Flathead Sandstone. Calcium magnesium sodium sulfate water and sodium sulfate water with concentrations of dissolved solids greater than 1,000 milligrams per liter are common in the alluvium, Willwood Formation and Fort Union Formation. Water samples from six of eight wells completed in the Willwood Formation have trace concentrations of herbicides. Calcium carbonate water with small dissolved-solids concentrations is common in the aquifers in Paleozoic formations.

Wyoming↗
USGS1989

Hydrologic effects of pumpage from the Denver basin bedrock aquifers of northern El Paso County, Colorado

The Denver groundwater basin underlies a 6,700 sq-mi area in eastern Colorado. To assess current conditions of the four bedrock aquifers in the basin, water levels, streamflow gain and loss, and other data were collected. Current aquifer conditions in the southern part of the basin and likely response to various 100-year pumping scenarios were analyzed using a digital finite-difference model. Simulated predevelopment flow through the bedrock aquifers was about 59 cu ft/sec. Water level changes between 1978 and 1985, likely caused by variations in precipitation and in pumping and by lowering of the water table in the overlying Black Squirrel Creek alluvial aquifer, ranged from rises of more than 40 ft to declines of as much as 80 ft. In 1985, pumping from the bedrock aquifers was about 56 cu ft/sec. Simulations indicate that 43% of the pumpage came from a decrease in volume of groundwater in storage; 37% came from induced recharge and captured discharge. The remaining 20% came from a transient high rate of recharge from precipitation. A baseline 100-yr simulation, beginning in 1985, indicated minimal drawdowns for constant pumping at 1985 rates in the southern part of the basin. Other simulations indicated that the pumpage required to supply the needs of the projected population would be accompanied by drawdowns of as much as 1,300 ft and by large decreases in amount of groundwater in storage. Pumpage from a hypothetical well field, located where the aquifers are thickest , and from the aquifers underlying Colorado Springs also was simulated. (USGS)

Water-Resources Investigations Report↗
USGS1987

Geology and hydrology of the deep bedrock aquifers in eastern Colorado

Deep bedrock aquifers are present in rocks of Cretaceous through Pennsylvanian age in eastern Colorado. These aquifers are the Laramie-Fox Hills (the uppermost aquifer studied), Fort Hays-Codell, Dakota-Cheyenne, Entrada-Dockum, Lyons, and Fountain. Structural mapping indicates the aquifers are 2,000 to 9,000 ft below land surface in most of eastern Colorado but outcrop in local areas in a narrow band along the Front Range of the Rocky Mountains. Recharge primarily occurs in outcrops and produces a northerly or easterly groundwater flow to discharge areas along the South Platte or Arkansas Rivers. Deep aquifers also discharge by underflow to Kansas and Nebraska. Some water-yielding strata in the Dakota-Cheyenne aquifer are not in hydraulic connection with the aquifer, and abnormal fluid pressures, trapped hydrocarbons, and high dissolved-solids concentrations are found in these strata. Temperature and dissolved-solids mapping indicate water temperatures of 100 to 210 in northeastern Colorado and a zone of relatively fresh water extending through a 7,000 sq mi area of the Dakota-Cheyenne aquifer in southeastern Colorado. Water levels in the Laramie-Fox Hills aquifer continue to decline as much as 12 ft/yr in local areas near Denver.

Colorado↗
USGS1986

Example evaluation of a permit application for a proposed hazardous-waste landfill in eastern Adams County, Colorado

A project was undertaken by the U.S. Geological Survey in cooperation with the U. S. Environmental Protection Agency to demonstrate methods by which RCRA (Resources Conservation and Recovery Act of 1976) Part B permit applications might be evaluated. The purpose of the project was to prepare a report that would supplement a series of case studies to be made available to permit writers in the U.S. Environmental Protection Agency. Four sites in the United States were chosen for their potential applicability to geologically similar sites. The Adams County, Colorado, site was chosen to be representative of sites in the Upper Cretaceous Pierre Shale. The intent of this report is to provide an example of how available earth-science information might be used in evaluating an application and not to evaluate the acceptability of the site. Because this study is an evaluation of a permit application, the data used are limited to the data supplied in the application and in published reports. Of the five criteria required by the U.S. Environmental Protection Agency to be addressed in the permit application considered in the case study, the application was evaluated to be inadequate in addressing three criteria: (1) Site characterization, (2) ability to monitor the location, and (3) flow paths and 100-foot time of travel. Details of the inadequacies and a description of the information needed to eliminate the inadequacies are included in the report. (USGS)

Water-Resources Investigations Report↗
USGS1985

The Dakota aquifer near Pueblo, Colorado: Faults and flow patterns

The Dakota Sandstone and the underlying Purgatoire Formation consisting of the Glencairn Shale and Lytle Sandstone Members form a board outcrop at the southeastern margin of the Canon City Embankment. The two formations form the Dakota aquifer, which supplies water to many domestic, stock, and irrigation wells in addition to a few municipal wells in the 12-township study area. Five large faults and several small faults, all apparently of high angle, are found in the study area. Analysis of water levels and water quality shows that parts of some of these faults restrict the flow of groundwater in the Dakota aquifer. Lithology of the rocks, particularly in the Dakota Sandstone and in the Glencairn Shale Member, is extremely variable. The lithology appears to affect the flow regime, possibly by determining how a particular segment of a fault affects flow. (USGS)

Colorado↗