Groundwater flow--Computer simulation

It is a fundamental supposition in groundwater modeling that as the discretization of a model domain is increased, the model's precision increases accordingly (Anderson and Woessner, 1992). However, the quantifiable amount and specific circumstances of that benefit remain unclear. The purpose of this research is to examine the output variations discerned as a result of applying successively coarsened discretization scenarios to a groundwater model test case. The test models, comprised of both regular (square) and irregular forty-four individual model output solutions. Detailed analysis of the piezometric head values, mass balance flow terms, and solution convergence times for each model run provides valuable insight into the complex relationship existing between spatial discretization and its effect upon model output values. Consequently, the aforementioned relationship proves to be highly complex, often affecting multiple model parameters in dissimilar manners while maintaining consistency in others.

Aerial photo-interpretation, GIS analysis, and groundwater modeling were employed to determine the impact of permitted groundwater withdrawal, primarily for agricultural irrigation, on protected wetland communities within Jonathan Dickinson State Park (JDSP), Martin County Florida. Since 1952, much of the wetland habitat has succeeded to terrestrial pine flatwoods in the southwestern section of the wilderness preserve of JDSP. The drying trend can not be linked to natural hydrologic impact, but strongly correlates to groundwater drawdown calculated using a three-dimensional groundwater computer model.

The objective is to develop a groundwater flow model of the Surficial Aquifer System in the area of Plantation, Broward County, Florida, using the U.S. Geological Survey MODFLOW code and to make a comparison between the use of two supplementary contaminant transport models: MODPATH code and the MT3D code. The advantages and limitations of the two solute transport models are described and an evaluation is made of their accuracy with respect to delineation of traveltime related to capture zones of wells. Final results of the computer simulations indicate that this study area is sensitive to river bed hydraulic conductivity and the stress of the continuous pumping at a nearby wellfield. Therefore, a critical factor in selecting an appropriate flow model for delineating the traveltime-related capture zone of a well is a model which simplifies the flow system while still preserving hydrogeologic characteristics of the flow system.