2002-present Hydrologist, United States Geological Survey, W. Trenton, New Jersey.
I developed a proposal, based on the USGS Spatially-Referenced Regressions of Watershed Attributes (SPARROW) watershed model regression equation, for identifying stream monitoring networks that most reduce nutrient load prediction error using a first-order second-moment uncertainty analysis. I also wrote a proposal that explicitly addresses the issue of measurement scale, using a mathematically rigorous approach based on wavelet transforms and a bootstrapping re-sampling algorithm and, on the basis of the proposal, was one of seven USGS researchers to receive a Center of Excellence for Geospatial Information Science (CEGIS) award in FY2007. To assess the degree of streamflow alteration caused by increased urbanization for the USGS stormwater-TMDL project, I developed a VB.NET application that uses an innovative Bayesian Monte Carlo approach to identify the most likely set of unmeasurable watershed parameters that best describe observed streamflow. The methodology provides a formal maximum-likelihood framework to quantify parameter uncertainty when many different combinations of parameters can produce similar hydrographs, and addresses the issue of non-uniqueness in watershed response by producing multiple realizations of streamflow hydrographs for randomly generated parameter sets. In support of various USGS projects, I致e written several GIS-enabled VBA tools and Microsoft VB.NET applications. These applications provide user interfaces that reference methods and properties on ESRI ArcObjects to calibrate for watershed parameters, estimate distances between stream features, edit attributes of feature classes, perform uncertainty analysis, produce graphical output such as streamflow hydrographs, generate explanatory watershed variables as input to the USGS StreamStats regression equations for predicting peak flows in ungaged basins, create and calibrate NHD routes, and edit DEMs so that they honor natural drainage features and decrease monotonically towards watershed outlets.
1998-2002 Research Hydrologist, National Exposure Research Laboratory, Environmental Protection Agency, Athens, Georgia.
Responsible for developing subsurface flow and geologic characterization components of the Multimedia Integrated Modeling System (MIMS).
1997-1998 Visiting Assistant Professor, Department of Geology, State University of New York, Buffalo, New York.
Taught hydrogeology and introductory geology courses.
1996-1997 Research Assistant Professor, Energy and Geoscience Institute, University of Utah, Salt Lake City, Utah.
Developed an entropy-based model for quantifying interscale hydraulic conductivity information transfer.
1995-1996 Graduate Student Intern, Sandia National Laboratories, Albuquerque, New Mexico.
Used a Markov random field model to geostatistically characterize spatially-discrete sedimentary structure.
1992-1995 Graduate Research Assistant, Los Alamos National Laboratory, Los Alamos, New Mexico.
Developed an algorithm to identify optimal scales of hydraulic conductivity measurement.
1989-1992 Graduate Research Assistant, New Mexico Institute of Mining and Technology, Socorro, New Mexico.
Constructed a geostatistical model for characterizing multiple-scale aquifer heterogeneities.
1986-1989 Lead Senior Hydrogeologist, Geoscience Consultants, Ltd., Albuquerque, New Mexico.
Numerically simulated impacts of remedial recovery strategies for various oil refinery sites.
1984-1986 Staff Geohydrologist, Sergent, Hauskins, and Beckwith Geotechnical Engineers, Albuquerque, New Mexico.
Predicted movement of water and contaminants through partially-saturated uranium mill tailings at Department of Energy UMTRA Project sites.
1981-1984 Research Associate, Kansas Geological Survey, Lawrence, Kansas.
Developed an algorithm for identifying minimum rates of remediation well pumping required to hydraulically contain a plume of contaminated ground water.
1978-1981 Graduate Research Assistant, University of Arizona, Tucson, Arizona.
Developed integration models to predict atmospheric accumulation of bomb-generated isotopes.