John R. Nimmo
John is a Physicist and Project Chief of the Unsaturated Flow Processes Project. He has been with the USGS since October 1981. John conducts and publishes research on unsaturated flow and contamination problems; leads the project; advises other scientists and policy leaders inside and outside the USGS; reviews papers, proposals, and research programs; teaches and creates instructional materials; contributes to leadership of the Unsaturated-Zone Interest Group; and serves on editorial boards and professional-society committees. He has expertise in soil and porous-media physics, unsaturated-zone hydrology,experimental and measurement techniques, conceptual and semi-empirical modeling of unsaturated hydraulic properties and flow, and hydrologic contamination issues and processes. John has a Ph.D. in Physics (6/83) and M.S. in Physics (l2/76) from the University of Wisconsin, and a B.S. in Physics and Math (6/75) from the University of Redlands, California. Visit his home page.
Kim S. Perkins
Kim has been a full-time Hydrologist on the Unsaturated Flow Processes Project since May 1997. Kim's current research includes aquifer recharge estimation and the effects of spatial variability of recharge in humid regions. Kim coordinates the project's research with USGS personnel in Idaho, New Jersey, Colorado and elsewhere, manages project administrative and budgetary functions, serves as the project webmaster, and publishes and presents scientific results. She has expertise in soil science, unsaturated-zone hydrology, and field and laboratory techniques for measuring hydraulic properties. Kim has a B.S. in Soil Science (12/96) from the University of California, Berkeley, and an M.S. in hydrogeology from San Jose State University (8/05). Visit her home page.
Alumni of the UZ Flow Project
Post Docs and Visiting Scientists
Grace Su was a National Research Council Postdoctoral Associate with the Unsaturated-Zone Flow Project from 10/99 to 09/02. Her background is in hydrogeology and multi-phase/unsaturated flow and contaminant transport in porous media and fractured rocks. For her Ph.D. research work, she conducted laboratory experiments to examine mechanisms controlling flow and transport in unsaturated rock fractures. Her postdoctoral work included examination of the effect of flow occurring simultaneously through the rock matrix and fractures under unsaturated conditions. Grace has a B.S.E. in Civil and Environmental Engineering (5/94) from the University of Michigan, Ann Arbor,and an M.S. (5/95) and Ph.D. (10/99) in Civil and Environmental Engineering from the University of California, Berkeley. Relevant publication: Su, G.W., Nimmo, J.R., and Dragila, M.I., 2003, Effect of isolated fractures on accelerated flow in unsaturated porous rock: Water Resources Research, v. 39, no. 12.
Brian Ebel was a Research Hydrologist who worked with the UZ Flow Project from February 2008 to February 2010. His work on the project focused on preferential flow in the unsaturated zone, including (i) simulating radionuclide transport at Rainier Mesa and Shoshone Mountain at the Nevada Test Site, (ii) electrical resistivity tomography experiments, and (iii) damping of periodic net infiltration variations. Brian has a PhD from the Stanford University Hydrogeology Program. He is crrently with the USGS in Boulder, CO. Visit his home page.
Ben Mirus worked part-time with the Unsaturated Zone Flow Project as a Physical Scientist (11/2005 through 11/2007) before becoming a full-time Hydrologist on the project (1/2010-present). Ben’s research focuses on parameterizing and evaluating quantitative models of unsaturated zone flow processes. His previous work used inverse modeling to characterize soil-hydraulic properties in the Mojave National Preserve; he is currently work is on estimating radionuclide transport rates through the unsaturated zone at the Nevada Test Site. Ben has a Ph.D. in Hydrology from Stanford University (10/2009) and a B.A. in Geology from Pomona College (5/2001)Visit his home page.
Relevant publications: Mirus, B.B., and Nimmo, J.R., 2013; Mirus, BB, K Perkins, 2012; Mirus, B.B., Ebel, B.A., Heppner, C.S., Loague, K., 2011; Mirus, B.B., Loague, K., Cristea, N.C., Burges, S.J., Kampf, S.K., 2011; Mirus, B.B., Perkins, K.S., and Nimmo, J.R., 2011; Mirus, B.B., Perkins, K.S., Nimmo, J.R., and Singha, K., 2009.
Cinzia Rossi, Visiting Scientist with the Unsaturated-Zone Flow Project from 3/92 to 1/93, has formulated, tested, and published an analytical model of soil water retention that is physically realistic over the entire range from saturation to oven-dryness. She has a Ph.D. in Hydrology (2/92) from the University of Genoa. Cinzia currently works as a hydrologist with the Regional Authority of Liguria, Genoa, Italy.
Relevant publications: Rossi, C., and Nimmo, J. R., 1996; Rossi, C., and Nimmo, J. R., 1994.
Maria Clementina Caputo was a visiting scientist with the Unsaturated-Zone Flow Project from July-November 2003. She is currently working on a publication of her research in the UZ Flow Lab back in Italy. Since 2000 she has mainly been involved in research on the unsaturated flow with particular attention on the experimental measurement techniques to evaluate hydraulic properties on samples of coherent porous rock. Maria's current research includes the design new laboratory method, based on quasi-steady unsaturated flow in a centrifugal field, for measuring rock properties and development of instrumentation for the method's implementation. Maria has been an Italian National Research Council researcher since May 2001. Prior to that, she collaborated with the Water Research Institute from 11/94 to 04/200. She has a Ph.D. in Geology (7/93) from the University of Bari.
Ana M. Laguna was a visiting scientist working with John Nimmo's project from September 2004 through February 2005. She is a professor in the Applied Physics Department at the University of Córdoba, Spain, the same school where she earned her Ph.D. in agricultural engineering (6/89). Ana has worked on rainfall-induced and mechanical soil erosion with emphasis on the role of trees in the redistribution of rain and soil. Her recent work uses lattice-Boltzmann models to study processes such as tracer transport in fissures and the role of obstacles on the transport of soil and contaminants due to overland flow. At the USGS she collaborated on modeling investigations of soil moisture dynamics in the Mojave Desert.Relevant publications: Nimmo, J.R., Herkelrath, W.N., Laguna Luna, A.M., 2007.
Previous Project Staff
Karen Mello, Soil Scientist with the Unsaturated-Zone FlowProject from 7/88 to 9/90, has made lab measurements of hydraulic properties of UZ core samples from the Panoche and Palouse sites. She has a B.S. in Soil Science (6/88) from Cal Poly, San Luis Obispo.
Relevant publications: Nimmo, J. R., Akstin, K. C., and Mello, K. A., 1992; Nimmo, J. R. and Mello, K. A., 1991.
Stephanie Shakofsky, Hydrologist with the Unsaturated-Zone Flow Project from 3/91 to 2/97, has completed a wide variety of field and lab research related to the INEEL field site. She has a B.S. in Geology from the University of Illinois and an M.S. in Geology (12/93) from San Jose State University. Stephanie is the Executive Director of the California Center for Land Recycling.Relevant publications: Nimmo, J.R., Shakofsky, S.M., Kaminsky, J.F., and Lords, G.S., 1999; Shakofsky, S. M., and Nimmo, J. R., 1996; Shakofsky, S. M., 1995; Shakofsky, S. M., 1993.
Michelle A. Denton worked as a full-time Hydrologist with the Unsaturated-Zone Flow Project from 7/97 to 8/99. With emphasis on the INEEL field site, Michelle has reviewed and analyzed lab and field data, conducted field tests, developed advancements in unsaturated-flow models, and served as the project's report specialist and computer specialist. Michelle has a B.S. in Environmental Resources Engineering (5/97) and B.A. in Applied Mathematics (12/95) from Humboldt State University
Dean Miller worked with the project from 7/00 to 10/01. He conducted laboratory experiments to determine hydraulic and other properties of unsaturated porous media. Dean has a B.S. in Geology from the University of Wyoming (08/99).
Hubert Morel-Seytoux was been a volunteer with the UZ Flow Project from 12/96- 08/00, conducting and publishing research on the modeling of unsaturated hydraulic properties, especially water retention and capillary drive. Hubert is Professor Emeritus of Civil Engineering, Colorado State University, Fort Collins.
Relevant publications: Morel-Seytoux, H.J., Nimmo, J.R., 1999.
Sandy Chang worked part-time as a Hydrologist with the Unsaturated-Zone Project from 10/98 to 7/99. She measured water retention under vapor-dominated conditions and demonstrated promising correlations with specific-surface areas, which are more easily measured, for samples from the INEEL and Mojave Basin sites. She is working toward a B.S. degree in Hydrogeology and Geological Engineering at Stanford University.
Kari Winfield was a full-time Hydrologist with the Unsaturated-Zone Flow Project from August 1998 through May 2005. Kari has expertise in physics, geology, hydrology, and unsaturated flow. She developed and applied laboratory measurement techniques for unsaturated hydraulic properties and used the resulting data for developments of unsaturated flow theory and water resource assessment. Kari has an M.S. in Geology from San Jose State University (12/00) and a B.S. in Physics from the University of California, San Diego (3/94).Relevant publications: Perkins, K.S. and Winfield, K.A., 2007; Winfield, K.A., and Nimmo, J.R., 2006; Winfield, K.A., 2005; Winfield, K.A., 2003; Nimmo, J.R., and Winfield, K.A., 2002; Nimmo, J.R., Lewis, A.M., and Winfield, K.A., 2000; Winfield, K.A., 2000.
Kathy Akstin has been a hydrologist with the USGS since 10/80. She worked on our project's research actively in the 1980s. Kathy conducted lab measurements of soil hydraulic properties for development of the steady-state centrifuge method, for investigations of compaction effects on these properties, and for recharge-estimation applications. Kathy has a B.S. in Soil Science (6/78) from the University of California, Berkeley.Relevant publications: Nimmo, J. R., Stonestrom, D. A., and Akstin, K. C., 1994; Nimmo, J. R., Akstin, K. C., and Mello, K. A., 1992; Nimmo, J. R. and Akstin, K. C., 1988.
Daphne Szutu Relevant publications: Perkins, K.S., Nimmo, J.R., Medeiros, A.C., Szutu, D.J., and von Allmen, E., 2014.
David Lyons, Mechanical Engineering graduate student and part-time Hydrologist with the USGS from 7/89 to 2/91, designed and constructed an improved soil-packing machine based on the machine of Chuck Ripple (Ripple and others, 1973). David has an M.S. in Mechanical Engineering from Stanford University, and an M.B.A. degree from Stanford University.
David Yu, student and part-time Hydrologist with the USGS from 6/87 to 12/88, designed and constructed a soil-recoring machine for making minimally disturbed soil core samples from larger cores obtained with field drilling and sampling equipment.
S. Jane Liaw, a student and part-time Hydrologist with the Unsaturated-Zone Flow Project from 2/95 to 12/96, has made lab measurements of hydraulic properties of deep-UZ core samples from the Mojave Basin site, including steady-state centrifuge hydraulic conductivities for aquifer recharge estimates. Jane has a B.S. in Earth Systems from Stanford University and an M.S. in Public Health (6/00) from the University of California, Berkeley
Jeff Deason, as a student and part-time Hydrologist with the Unsaturated-Zone Flow Project from 7/96 to 6/98, conducted research and completed a thesis on Mojave Basin research. Jeff has an M.S. in Environmental Systems (6/98) and B.S. in Environmental Systems (6/97) from Stanford University Relevant publications: Nimmo, J.R., Deason, J.A., Izbicki, J.A., and Martin, P., 2002; Deason, J. A., 1997.
Angus M. Lewis, graduate student and part-time Hydrologist with the Unsaturated-Zone Flow Project from 6/97 to 5/99, has conducted lab experiments for the MRGB study and interpreted the results to upscale point-recharge measurements on the basis of basin subregions and their identifiable geomorphic characteristics. Angus has an M.S. in Geology (12/00) from San Jose State University and a B.S. in Math (6/93) from Cal Poly, San Luis Obispo.
Relevant publications: Nimmo, J.R., Perkins, K.S., and Lewis, A.M., 2002; Lewis, A.M., 2000; Nimmo, J.R., Lewis, A.M., and Winfield, K.A., 2000; Lewis, A.M., Nimmo, J. R., and Stonestrom, D.A., 1999; Lewis, A.M. and Nimmo, J.R., 1998.
Chris Heppner was a part-time hydrologist with the Unsaturated Zone Flow Project from April 2003 to March 2005. He has expertise in hydrogeology, near-surface hydrologic response, and conceptual and numerical modeling. His work with the UZ Flow Project focused on field and modeling studies of groundwater recharge at two humid region sites, one in Pennsylvania and the other in Minnesota. Chris has a B.S in Geology/Biology from Brown University (5/98) and recieved a Ph.D. in Hydrogeology at Stanford University.
Relevant publications: Mirus, B.B., Ebel, B.A., Heppner, C.S., Loague, K., 2011; Heppner, C.S., Nimmo, J.R., Folmar, G.J., Gburek, W.J., and Risser, D.W., 2007; Heppner, C.S., and John R. Nimmo, J.R., 2005.
Lara MitchellRelevant publications: Nimmo, J.R., Horowitz, C., and Mitchell, L., 2015; Nimmo, J.R., Mitchell, L., 2013
Ferdinando MannaRelevant publications:
Sabrina Belknap was a full-time student intern for the summer of 2004. Her work with the UZ Flow Project involved planning and preparing for an infiltration experiment which will be used to determine soil moisture properties in the Mojave Desert. In 2004 she graduated from the University of Toledo with a B.S. in Environmental Geology. In Fall, 2004 she started working toward her M.S. in eology at the University of North Carolina-Chapel Hill.
Jane Duxbury was a full-time student intern for the summer of 2005 after completing her BS in Geology from San Francisco State University. Her work with the UZ Flow Project involved planning and conducting a field infiltration experiment to examine soil-age dependent hydraulic properties in the Mojave Desert in relation to habitat suitability. In Fall 2005 she started working toward her M.S. in Geology at the University of Vermont.
Charles Horowitz Relevant publications: Nimmo, J.R., Horowitz, C., and Mitchell, L., 2015.