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The use of trade, product, industry, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. PREFACE This report describes an enhanced version of the U.S. Geological Survey modular groundwater model, called MODFLOW-2000, for which the structure has been expanded to facilitate the solution of multiple related(More)
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Integrated environmental modeling (IEM) represents a new paradigm, inspired by modern environmental problems, decisions, and policies and enabled by transdisciplinary science and computer capabilities that allow the environment to be considered in a fundamentally different way. The problems are characterized by the extent of the geo-ecological system(More)
The use of trade, product, industry, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. PREFACE This report describes a computer program that links MODFLOW-2000, the U.S Geological Survey modular three-dimensional finite-difference groundwater model, with an advanced technique for solving matrix equations,(More)
i PREFACE The computer software described in this report is a new capability of the Advective-Transport Observation (ADV2) Package for MODFLOW-2000, the U.S. Geological Survey's three-dimensional groundwater flow parameter-estimation model. The software is designed to allow effective porosity, which is used to calculate seepage velocity from specific(More)
Many methods can be used to test alternative ground water models. Of concern in this work are methods able to (1) rank alternative models (also called model discrimination) and (2) identify observations important to parameter estimates and predictions (equivalent to the purpose served by some types of sensitivity analysis). Some of the measures investigated(More)
We report on the reproducibility of human observers' vanishing detection thresholds for visual targets in contrast-detail (C/D) analysis of ultrasound B-mode images. The images used in this study contain visual targets which are circular cross sections of constant-contrast conical structures in the C/D phantom. The vanishing threshold diameters for these(More)