Computational Geohydrologist
Computational Geohydrologist


Glenn Hammond is a computational geohydrologist and senior research scientist at PNNL. He began developing simulation tools for geoscientific engineering applications during his undergraduate education at Brigham Young University where he programmed Groundwater Modeling System, a graphical user interface used for groundwater simulators, such as MODFLOW. At the University of Illinois, Hammond researched reactive transport as a U.S. Department of Energy (DOE) Computational Science graduate fellow, developing physics-based preconditioning algorithms for biogeochemical transport on supercomputers. His graduate research led him to a career within DOE national laboratories, where he continues to research the application of supercomputing to geoscientific applications. Hammond is the principal developer of PFLOTRAN, an open source, massively parallel code for simulating reactive multiphase flow and transport processes in the subsurface. Over the past ten years, he has taught numerous PFLOTRAN short courses to hundreds of researchers from around the world.

Research Interest

Hammond's research interests focus on the development of flexible and increasingly accurate computational methodologies and tools for simulating geoscientific processes in the Earth’s subsurface on supercomputers. He enjoys collaborating within the PFLOTRAN developer and user communities.

Disciplines and Skills

  • Computational science
  • Geohydrology
  • High-performance computing
  • Reactive biogeochemical transport
  • Software development


  • PhD in Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 2003
  • MS in Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 1999
  • BS in Civil and Environmental Engineering, Brigham Young University, 1997

Affiliations and Professional Service

  • American Geophysical Union, Hydrology Section

PFLOTRAN Short Courses:

  • University of Bern, Bern, Switzerland (2019)
  • International High-Level Radioactive Waste Management 2019, Knoxville, TN (2019)
  • Commonwealth Scientific and Industrial Research Organisation, Adelaide, Australia (2019)
  • Vanderbilt University (Kevin Brown), Albuquerque, NM (2019)
  • TaiPower, Taipei, Taiwan (2018)
  • Interagency Steering Committee on Performance and Risk Assessment Community of Practice Annual Technical Exchange Meeting, Albuquerque, NM (2017)
  • Amphos21 - Migration 2019, Barcelona, Spain (2017)
  • Sandia National Laboratories, Albuquerque, NM (2017)
  • New Mexico Tech, Socorro, NM (2014)
  • Sandia National Laboratories, Carlsbad, NM (2013)
  • Sandia National Laboratories, Albuquerque, NM (2012)
  • Los Alamos National Laboratory, Los Alamos, NM (2012)
  • University of Texas at Austin (Marc Hesse), Austin, TX (2012)



  • Song X, X Chen, M Ye, Z Dai, G Hammond, and JM Zachara. (2019) “Delineating Facies Spatial Distribution by Integrating Ensemble Data Assimilation and Indicator Geostatistics with Level-Set Transformation.” Water Resources Research, 55, doi: 10.1029/2018WR023262
  • Dai H, X Chan, M Ye, X Song, G Hammond, B Hu, and JM Zachara. (2019) “Using Bayesian Networks for Sensitivity Analysis of Complex Biogeochemical Models.” Water Resources Research, 55, doi: 10.1029/2018WR023589.
  • Shuai P, X Chen, X Song, GE Hammond, J Zachara, P Royer, H Ren, WA Perkins, MC Richmond, and M Huang. (2019) “Dam Operations and Subsurface Hydrogeology Control Dynamics of Hydrologic Exchange Flows in a Regulated River Reach.” Water Resources Research, doi: 10.1029/2018WR024193.


  • Bisht G, WJ Riley, GE Hammond, and DM Lorenzetti. (2018) “Development and evaluation of a variably saturated flow model in the global E3SM Land Model (ELM) version 1.0.” Geoscientific Model Development, v11, p4085-4102, doi: 10.5194/gmd-11-4085-2018.
  • Song X, X Chen, J Stegen, G Hammond, H Song, H Dai, E Graham, and JM Zachara. (2018) “Drought Conditions Maximize the Impact of HighFrequency Flow Variations on Thermal Regimes and Biogeochemical Function in the Hyporheic Zone.” Water Resources Research, doi: 10.1029/2018WR022586.
  • Bao J, T Zhou, M Huang, W Perkins, S Harding, S Titzler, G Hammond, H Ren, P Thorne, S Suffield, C Murray, and J Zachara. (2018) “Modulating Factors of Hydrologic Exchanges in a Large-Scale River Reach: Insights from Three-Dimensional Computational Fluid Dynamics Simulations.” Hydrological Processes, doi: 10.1002/hyp.13266.
  • Zhou T, J Bao, M Huang, Z Hou, E Arntzen, X Song, SF Harding, PS Titzler, H Ren, CJ Murray, WA Perkins, X Chen, JC Stegen, GE Hammond, PD Thorne, and JM Zachara. (2018) “Riverbed Hydrologic Exchange Dynamics in a Large Regulated River Reach.” Water Resources Research, 54, 4, doi: 10.1002/2017WR020508.
  • Bisht G, M Huang, T Zhou, X Chen, H Dai, GE Hammond, WJ Riley, JL Downs, Y Liu, and JM Zachara. (2017) “Coupling a three-dimensional subsurface flow and transport model with a land surface model to simulate stream–aquifer–land interactions (CP v1.0).” Geoscientific Model Development, 10, 4539-4562, doi: 10.5194/gmd-10-4539-2017.
  • Johnson TC, GE Hammond, and X Chen. (2017) “PFLOTRAN-E4D: A parallel open source PFLOTRAN module for simulating time-lapse electrical resistivity data.” Computers & Geosciences, v99, p72-80, doi: 10.1016/j.cageo.2016.09.006.
  • Bartlett R, I Demeshko, T Gamblin, G Hammond, M Heroux, J Johnson, A Klinvex, X Li, L Curfman McInnes, JD Moulton, D Osei-Kuffuor, J Sarich, B Smith, J Willenbring, and U Meier Yang. (2017) “xSDK Foundations: Toward an Extreme-scale Scientific Software Development Kit.” Supercomputing Frontiers and Innovations, v4, n1, doi: 10.14529/jsfi170104.
  • Trinchero P, J Molinero, G Deissmann, U Svensson, B Gylling, H Ebrahimi, G Hammond, D Bosbach, I Puigdomenech. (2016) “Implications of grain-scale mineralogical heterogeneity for radionuclide transport in fractured media.” Transport in Porous Media, DOI 10.1007/s11242-016-0765-0.
  • Zachara J, X Chen, C Murray, and G Hammond. (2016) “River stage influences on uranium transport in hydrologically dynamic groundwater-surface water transition zone.” Water Resources Research, 52, doi:10.1002/2015WR018009.
  • Tang G, F Yuan, G Bisht, GE Hammond, PC Lichtner, J Kumar, RT Mills, X Xu, B Andre, FM Hoffman, SL Painter, and PE Thornton. (2016) “Addressing numerical challenges in introducing reactive transport code into a land surface model: a biogeochemical modeling proof-of-concept with CLM-PFLOTRAN 1.0.” Geoscientific Model Development, 9, p927-946, doi:10.5194/gmd-9-927-2016.
  • Johnson T, R Versteeg, J Thomle, G Hammond, X Chen, and J Zachara. (2015) “Four-dimensional electrical conductivity monitoring of stage-driven river instruction: Accounting for water table effects using a transient mesh boundary and conditional inversion constraints.” Water Resources Research, 51, doi:10.1002/2014WR016129.
  • Hammond GE, PC Lichtner, and RT Mills. (2014) “Evaluating the Performance of Parallel Subsurface Simulators: An Illustrative Example with PFLOTRAN.” Water Resources Research, 50, doi:10.1002/2012WR013483.
  • Gardner WP, G Hammond, and P Lichtner. (2013) “High Performance Simulation of Environmental Tracers in Heterogeneous Domains.” Groundwater, doi:10.1111/gwat.12148.
  • Chen X, G Hammond, C Murray, M Rockhold, V Vermeul, and J Zachara. (2013) “Application of Ensemble-based Data Assimilation Techniques for Aquifer Characterization using Tracer Data at Hanford 300 Area.” Water Resources Research, 49, doi:10.1002/2012WR013285.
  • Keyes D, L Curfman McInnes, C Woodward, W Gropp, E Myra, M Pernice, J Bell, J Brown, J Connors, E Constantinescu, D Estep, K Evans, C Farhat, A Hakim, G Hammond, G Hansen, J Hill, T Isaac, X Jiao, K Jordan, D Kaushik, E Kaxiras, K Lee, A Lott, Q Lu, J Magerlein, R Maxwell, M McCourt, M Mehl, R Pawlowski, A Randles, D Reynolds, B Riviere, T Scheibe, J Shadid, B Sheehan, M Shephard, A Siegel, B Smith, X Tang, C Wilson, and B Wohlmuth. (2013) “Multiphysics Simulations: Challenges and Opportunities.” International Journal of High Performance Computing Applications, v27, n1, p4-83, doi: 10.1177/1094342012468181.
  • Navarre-Sitchler A, RM Maxwell, ER Siirila, GE Hammond, and PC Lichtner. (2013) “Elucidating geochemical response of shallow heterogeneous aquifers to CO2 leakage using high-performance computing: implications for monitoring CO2 sequestration.” Advances in Water Resources, v53, p45-55, doi:10.1016/j.advwatres.2012.10.005.
  • Chen X, H Murakami, M Hahn, GE Hammond, ML Rockhold, JM Zachara, and Y Rubin. (2012) “Three-Dimensional Bayesian Geostatistical Aquifer Characterization at the Hanford 300 Area using Tracer Test Data.” Water Resources Research, 48, doi:10.1029/2011WR010675.
  • Hammond GE, PC Lichtner, C Lu, and RT Mills. (2012) “Chapter: PFLOTRAN: Reactive flow and transport code for use on laptops to leadership-class supercomputers.” Ebook: Groundwater Reactive Transport Models, Editors: Zhang F, GT Yeh, and JC Parker, Bentham Science Publishers, p141-159, eISBN: 978-1-60805-306-3, doi:10.2174/978160805306311201010141.
  • Lichtner PC and GE Hammond. (2012) “Using High Performance Computing to Understand Roles of Labile and Nonlabile U(VI) on Hanford 300 Area Plume Longevity.” Vadose Zone Journal, v11, n2, doi:10.2136/vzj2011.0097.
  • Hammond GE, PC Lichtner, and ML Rockhold. (2011) “Stochastic Simulation of Uranium Migration at the Hanford 300 Area.” Journal of Contaminant Hydrology, v120-121, p115-128, doi:10.1016/j.jconhyd.2010.04.005.
  • Hammond, G.E. and P.C. Lichtner (2010) Field-Scale Modeling for the Natural Attenuation of Uranium at the Hanford 300 Area using High Performance Computing, Water Resources Research, 46, W09527, doi:10.1029/2009WR008819.
  • Hammond GE, AJ Valocchi, and PC Lichtner. (2005) “Application of Jacobian-free Newton-Krylov with physics-based preconditioning to biogeochemical transport.” Advances in Water Resources, v28, n4, p359-376.