The Windows®-based application Hantush is designed to determine aquifer parameters simultaneously and uniquely based on time-drawdown data collected from a single observation well near a pumping well partially penetrating a leaky confined aquifer.  The Hantush (1964) solution is analyzed inversely for the identification of hydraulic properties using the Taylor series and a nonlinear least-squares method. The computer program determines the horizontal hydraulic conductivity, the vertical hydraulic conductivity, the storage coefficient, and the leakage factor of the overlying aquitard from field measured time-drawdown data and other information provided by the user.

Few limitations seem to apply in the use of the program.  It does require that the characteristics of the observation-well and pumping-well construction be known and that the observation well be located within a radial distance of 1.5b(Kr /Kz)½ (b is the aquifer thickness, Kr is the horizontal hydraulic conductivity, Kz is the vertical hydraulic conductivity) from the pumping well.  It also requires that the user provide initial estimates of the aquifer parameters.  These estimates can be within two orders of magnitude of the actual values; however, if convergence is not achieved, the algorithm results may provide a better estimate to be used in a second trial.  In the case of poor quality data, some caution should be exercised in the interpretation of the results since the method produces aquifer property values based on a "best fit " process.

The computer program SynSeis (Synthetic Seismogram) was developed to generate a synthetic seismogram for user-defined field parameters.  SynSeis is an interactive Windows® application written in Microsoft® Visual Basic and developed for IBM®-compatible personal computers.  The intent is to provide a simple design tool to be used by those not experienced in seismic-data acquisition, but actively involved in the planning and execution of field studies.

SRIM is a Windows®-based adaptation of a seismic refraction inverse modeling computer program (FSIP1) written in FORTRAN by Scott, et. al (1972) to run on main-frame computer systems and modified later by Haeni, et. al (1987) to run on micro and personal computers (version SIPT1). The program generates a two-dimensional model representing a layered-earth depth interpretation. Travel times are picked from seismic records by the user. These times, together with shot point and geophone locations and refraction layer control information, are submitted to the program via a data file. A first approximation delineation of each refraction horizon is obtained by a computer adaptation of the delay-time method. The approximation is then tested and improved by the program through the use of a ray-tracing procedure in which ray travel times computed for the model are compared against field-measured travel times. The model is subsequently adjusted in an iterative manner so as to minimize the discrepancy between computed and measured travel times.

The Windows®-based program SynGen generates a synthetic seismogram for a user-defined layered-earth model to be used as an aid in the interpretation of shallow seismic reflection data and as a tool in the design of field surveys.  The program is capable of producing a one-dimensional synthetic seismogram for a given geologic column or may be used to create a pseudo two-dimensional synthetic seismogram of more complex stratigraphy.  However, in the latter case, the assumption is made that reflectors beneath the trace gather are horizontal and that the trace represents the response of a normally incident ray path coincident with the trace location.  Other capabilities of the program are:  selection of four types of source wavelets; selection of four methods of displaying the synthetic seismogram; and incorporation of signal attenuation (spherical divergence and distance traveled).

The Windows®-based program InterpretVES was developed to process direct current resistivity sounding data collected in the field using the Schlumberger electrode configuration and aid in the interpretation of the resultant vertical electrical sounding curves.  The computer program is actually composed of two algorithms that use the method of steepest descent to generate a layered-earth model from the analysis of the sounding curves.  One algorithm requires that the user input thickness and resistivity values for each layer as an initial approximation to the actual conditions in the subsurface.  The algorithm adjusts the parameters (thickness and resistivity, but not the number of layers) of the initial model until the computed VES curve fits the field VES curve within a user-defined criteria.  The other algorithm computes a best-fit model by first assuming the model is composed of as many layers as there are apparent resistivity measurement values and then reducing the number of layers until the computed VES curve fits the field VES curve within a user-defined criteria.

The Windows®-based program RefractTimes was developed to determine compressional wave travel times from a seismic source to receivers located over a stratified earth with planar dipping interfaces separating geologic units.  The user supplies a model of the underlying layered earth (up to five layers) and spread geometry (up to 48 geophones) as input.  Travel times as determined using a set of equations that honor the rule of reciprocity.

The Windows®-based program RefractSoln was developed to interpret seismic refraction data collected over a stratified earth with planar dipping interfaces separating geologic units.  Travel time pairs and spread information are entered into the program using data-entry dialog windows.  The processing algorithm uses a set of equations that determines the compressional wave velocities and the vertical depths at geophone locations for each layer represented in the field data.  The program can compute layer parameters for up to five layers with any orientation of dip angle.  Required input information is obtained from the configuration of the shot-geophone spread used in the survey and from the arrival-time data derived from the field seismogram.

The Windows®-based program UnConfined was developed to determine the horizontal hydraulic conductivity, vertical hydraulic conductivity, storage coefficient, and specific yield of an unconfined aquifer using time-drawdown observations obtained from observation well and/or piezometers located around a fully or partially penetrating pumping well.  These hydraulic properties are determined simultaneously using the Neuman (1974) solution for delayed release of water and the Moench (1995) solution for the instantaneous release of water from the aquifer.  The user supplies measurements of time and associated drawdown for any number of observation points, initial estimates of aquifer properties, and geometric parameters for the pumping well/observation point network.

The Windows® application RandomWalk is a visualization tool to be used in the simulation of mass transport within an aquifer that contains sources and sinks. RandomWalk can be used to evaluate groundwater contamination problems and to test various remediation scenarios.  The intent of this program is to provide the user with an interactive tool for the visualization of contaminant movement within a relatively simplified flow system.  It is not meant to be used in the context of solving contaminant movement problems in the real world.  A more complicated approach would be necessary for such cases.

The Windows® application GWRECH is an adaptation of a soil moisture budget model developed by Fred J. Otradovsky of the U.S. Bureau of Reclamation with minor code alterations made later by John Peckenpaugh and Fred Lappala of the U.S. Geological Survey. In GWRECH, an additional modification to the original code is the addition of a routine to compute potential evapotranspiration using the modified Jensen-Haize method. The combined methodologies included in GWRECH have been applied to various hydrologic studies in Nebraska and has been useful in situations where climate data were limited.

The Windows® application WellNetDesign is a program to aid water-resource professionals in the design of pump tests in unconfined aquifers. The program uses sensitivity coefficients, the distribution of relative errors and the correlation coefficients between four (estimated) aquifer parameters (horizontal and vertical hydraulic conductivity, Kr and Kz, respectively; storage coefficient, S; and specific yield, Sy) as criteria for the placement of observation wells in the vicinity of the pumping well. Contours of the relative errors over a vertical profile are graphically displayed to aid the user in selecting the "best" location for observation wells and the placement of screens.