John R. Nimmo, Ph. D.
John R. Nimmo is a Research Physicist Emeritus for the USGS Water Resources Mission Area.
John R. Nimmo, Research Physicist Emeritus, is working toward establishment of a sound twenty-first century framework of water flow processes in soil and rock. His specialty is the unsaturated zone, between land surface and the water table. He collaborates with other USGS scientists to advance hydrologic science through observation and experiment, mathematical modeling, and development of theory.
Research overview
Problems of water availability and water quality require measurement, prediction, and understanding of the unsaturated-zone dynamics of water and substances it carries—applications include aquifer recharge estimation, ecosystem preservation and restoration, contaminant transport, and hydrologic impacts of land-use and climate change. Through collaboration with the geographically-based Water Science Centers, other units of the Water Mission Area, and the larger scientific community, great progress is possible through in-depth investigations, theory and method development, and field experiments.
Current and recent emphases include:
(1) Preferential flow through unsaturated soil and rock.
(2) Aquifer recharge estimation, including episodic as well as continuous components.
(3) Expert-guided automated techniques of hydrograph analysis for exchanges of water between aquifers and the land surface, the unsaturated zone, and streams and lakes.
(4) Effects of climate change, especially storm characteristics and precipitation, on water resources.
(5) Vulnerability of aquifers to contamination through unsaturated-zone transmission.
(6) Advancement of measurement techniques for unsaturated hydraulic properties, especially simple, low-technology methods for rapid characterization of areally-diverse field sites.
Career Overview
I earned a Ph.D. in physics in 1983 at the University of Wisconsin, with a specialty in porous media physics and minor in soil science. I then began full-time work in the USGS. My early career focused mainly on lab experiments and measurement techniques related to soil hydraulic properties, with the main application being aquifer-recharge estimation. Since the 1990s I have broadened my research efforts: (1) topically, to permit a more complete treatment of the inherently multidisciplinary concerns of earth science, (2) methodologically, to select from a large toolbox of lab, field, theoretical, and modeling techniques to best approach a given problem, and (3) geographically, to broaden the applicability of my work to a wide range of climate, geology, soils, hydrology, vegetation, and land use. Besides research, I contribute much effort to teaching, consultation, review of research papers and programs, and leadership of scientific groups within and outside the USGS.
Science and Products
Review of the transport of selected radionuclides in the interim risk assessment for the Radioactive Waste Management Complex, Waste Area Group 7 Operable Unit 7-13/14, Idaho National Engineering and Environmental Laboratory, Idaho
Unsaturated zone flow processes
Aquifer recharge
Estimating soil hydraulic parameters from transient flow experiments in a centrifuge using parameter optimization technique
The soil physics contributions of Edgar Buckingham
Quasi‐steady centrifuge method for unsaturated hydraulic properties
Hydraulic and geochemical framework of the Idaho National Engineering and Environmental Laboratory vadose zone
The life and scientific contributions of Lyman J. Briggs
How fast does water flow in an unsaturated macropore? Evidence from field and lab experiments
Effect of isolated fractures on accelerated flow in unsaturated porous rock
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Review of the transport of selected radionuclides in the interim risk assessment for the Radioactive Waste Management Complex, Waste Area Group 7 Operable Unit 7-13/14, Idaho National Engineering and Environmental Laboratory, Idaho
The U.S. Department of Energy (DOE) requested that the U.S. Geological Survey conduct an independent technical review of the Interim Risk Assessment (IRA) and Contaminant Screening for the Waste Area Group 7 (WAG-7) Remedial Investigation, the draft Addendum to the Work Plan for Operable Unit 7-13/14 WAG-7 comprehensive Remedial Investigation and Feasibility Study (RI/FS), and supporting documentsAuthorsJoseph P. Rousseau, Edward R. Landa, John R. Nimmo, L. DeWayne Cecil, LeRoy L. Knobel, Pierre D. Glynn, Edward M. Kwicklis, Gary P. Curtis, Kenneth G. Stollenwerk, Steven R. Anderson, Roy C. Bartholomay, Clifford R. Bossong, Brennon R. OrrUnsaturated zone flow processes
Water flow in the unsaturated zone is greatly influenced by unsaturated hydrostatics (water content, energy, pressure, and retention) and by unsaturated hydrodynamics (diffuse flow and preferential flow). Important multiphase processes include the transport of gases, nonaqueous liquids, and solid particles. Numerous means are available for determination of unsaturated conditions and properties, boAuthorsJohn R. NimmoAquifer recharge
No abstract available.AuthorsJohn R. Nimmo, Richard W. Healy, David A. StonestromEstimating soil hydraulic parameters from transient flow experiments in a centrifuge using parameter optimization technique
A modified version of the Hydrus software package that can directly or inversely simulate water flow in a transient centrifugal field is presented. The inverse solver for parameter estimation of the soil hydraulic parameters is then applied to multirotation transient flow experiments in a centrifuge. Using time‐variable water contents measured at a sequence of several rotation speeds, soil hydraulAuthorsJirka Šimůnek, John R. NimmoThe soil physics contributions of Edgar Buckingham
During 1902 to 1906 as a soil physicist at the USDA Bureau of Soils (BOS), Edgar Buckingham originated the concepts of matric potential, soil–water retention curves, specific water capacity, and unsaturated hydraulic conductivity (K) as a distinct property of a soil. He applied a formula equivalent to Darcy's law (though without specific mention of Darcy's work) to unsaturated flow. He also contriAuthorsJ. R. Nimmo, E. R. LandaQuasi‐steady centrifuge method for unsaturated hydraulic properties
We have developed the quasi‐steady centrifuge (QSC) method as a variation of the steady state centrifuge method that can be implemented simply and inexpensively with greater versatility in terms of sample size and other features. It achieves these advantages by somewhat relaxing the criterion for steadiness of flow through the sample. This compromise entails an increase in measurement uncertaintyAuthorsMaria C. Caputo, John R. NimmoHydraulic and geochemical framework of the Idaho National Engineering and Environmental Laboratory vadose zone
Questions of major importance for subsurface contaminant transport at the Idaho National Engineering and Environmental Laboratory (INEEL) include (i) travel times to the aquifer, both average or typical values and the range of values to be expected, and (ii) modes of contaminant transport, especially sorption processes. The hydraulic and geochemical framework within which these questions are addreAuthorsJohn R. Nimmo, Joseph P. Rousseau, Kim S. Perkins, Kenneth G. Stollenwerk, Pierre D. Glynn, Roy C. Bartholomay, LeRoy L. KnobelThe life and scientific contributions of Lyman J. Briggs
Lyman J. Briggs (1874–1963), an early twentieth century physicist at the U.S. Department of Agriculture (USDA), made many significant contributions to our understanding of soil-water and plant-water interactions. He began his career at the Bureau of Soils (BOS) in 1896. At age 23, Briggs published (1897) a description of the roles of surface tension and gravity in determining the state of static sAuthorsEdward R. Landa, John R. NimmoHow fast does water flow in an unsaturated macropore? Evidence from field and lab experiments
A wide range of available field and lab evidence can lead to useful generalizations about the speed of macropore flow, which often dominates the transport of water and contaminants. In 36 published field tests, the values of maximum transport speed in macropores and other preferential channels vary surprisingly little. The available tests vary widely in type of medium, including fractured rock andAuthorsJohn R. NimmoEffect of isolated fractures on accelerated flow in unsaturated porous rock
Fractures that begin and end in the unsaturated zone, or isolated fractures, have been ignored in previous studies because they were generally assumed to behave as capillary barriers and remain nonconductive. We conducted a series of experiments using Berea sandstone samples to examine the physical mechanisms controlling flow in a rock containing a single isolated fracture. The input fluxes and frAuthorsGrace W. Su, John R. Nimmo, Maria I. Dragila