About Me

I am an environmental engineer specializing in groundwater at Sandia National Laboratories, in Carlsbad, New Mexico. My interests are centered around “computational hydrogeophysics”; numerical methods and the numerical aspects related to the analytical and semi-analytical solutions to flow and transport problems in hydrology and geophysics. The subset of this that I personally find interesting is the application of integral transforms and special functions to hydrogeology.

My transient analytic element (LT-AEM) code, my unconfined well-test analysis code, and codes associated with solutions published in various journal papers are free software, are available for download below, and might be useful to others. I can provide help getting started.

Anything I write or provide on this website is solely my personal opinion and responsibility, and does not represent my employer's opinion or product.

Kristopher L. Kuhlman
Repository Performance Department
Sandia National Laboratories
4100 National Parks Highway
Carlsbad, New Mexico 88220
office phone: (505) 845-0938

Publications

Under Review

• Mishra, P.K. & K.L. Kuhlman. "Unconfined Aquifer Flow Theory – from Dupuit to present" in Advances in Hydrogeology, Cambridge Press. (draft available)
• Kuhlman, K.L., 2012. Comparison of Inverse Laplace Transform Algorithms for Laplace-Space Numerical Approaches, submitted to Numerical Algorithms, (draft available from arXiv).
• Ji, S.-H., Y.-K. Koh, K.L. Kuhlman, M.-Y. Lee, & J.-W. Choi. Influence of Pressure Change During Hydraulic Tests on Fracture Aperture, submitted to Ground Water.
• Malama, B. & K.L. Kuhlman. Models for Unsaturated Hydraulic Conductivity Based on Truncated Lognormal Pore-size Distributions, submitted to Journal of Hydrology, (draft available).

Peer Reviewed

• Mishra, P.K., V.V. Vesselinov & K.L. Kuhlman, 2012. Saturated-Unsaturated flow in a Compressible Leaky-unconfined Aquifer, Advances in Water Resources, 42(XX), 62–70. (draft available from arXiv).
• Malama, B., K.L. Kuhlman, W. Barrash, M. Cardiff & M. Thoma, 2011. Modeling slug tests in unconfined aquifers taking into account water table kinematics, wellbore skin and inertial effects, Journal of Hydrology, 408(1–2), 113–126. (download draft manuscript and code)
• Bakker, M. & K.L. Kuhlman, 2011. Computational issues and applications of line-elements to model subsurface flow governed by the modified Helmholtz equation, Advances in Water Resources, 34(9), 1186–1194. (download draft manuscript and code)
• Kuhlman, K.L. & E. Pardo-Igúzquiza, 2010. Universal cokriging of hydraulic heads accounting for boundary conditions, Journal of Hydrology, 384(1–2), 14–25. (download draft manuscript and code)
• Malama, B., K.L. Kuhlman & A. Revil, 2009. Theory of transient streaming potentials associated with axial-symmetric flow in unconfined aquifers, Geophysical Journal International, 179(2), 990–1003. (download code)
• Kuhlman, K.L. & S.P. Neuman, 2009. Laplace-transform analytic-element method for transient porous-media flow, Journal of Engineering Mathematics, 64(2), 113–130. (download draft manuscript and code)
• Malama, B., A. Revil & K.L. Kuhlman, 2009. A semi-analytical solution for transient streaming potentials associated with confined aquifer pumping tests, Geophysical Journal International, 176(3), 1007–1016. (download code)
• Malama, B., K.L. Kuhlman & W. Barrash, 2008. Semi-analytical solution for flow in a leaky unconfined aquifer toward a partially penetrating pumping well, Journal of Hydrology, 356(1-2), 234–244. (download draft manuscript and code)
• Kuhlman, K.L., 2008. Laplace transform analytic element method for transient groundwater flow simulation, PhD Dissertation, University of Arizona. (download LT-AEM code)
• Kuhlman, K.L. & A.W. Warrick, 2008. Quasilinear infiltration from an elliptical cavity, Advances in Water Resources, 31(8), 1057–1065. (download draft manuscript and code)
• Kuhlman, K.L., A.C. Hinnell, P.K. Mishra & T.-C.J. Yeh, 2008. Basin-scale transmissivity and storativity estimation using hydraulic tomography, Ground Water, 46(5), 706–715. (download draft manuscript)
• Malama, B., K.L. Kuhlman & W. Barrash, 2007. Semi-analytical solution for flow in leaky unconfined aquifer-aquitard systems, Journal of Hydrology, 346(1-2), 59–68. (download draft manuscript and code)

Conference Proceedings

• Kuhlman, K.L., B. Malama & S.C. James, 2011. Parameter Uniqueness And Uncertainty Associated For Multirate Transport Models Applied To Core-Scale Test Data. American Geophysical Union, San Francisco, CA, Fall Meeting 2011, abstract H31D-1179 (poster).
• Kuhlman, K.L. & K.S. Barnhart, 2011. Hydrogeology Associated with the Waste Isolation Pilot Plant. American Nuclear Society, Albuquerque, NM, International High-Level Radioactive Waste Management Conference, paper 3317 (paper and oral presentation).
• Kuhlman, K.L., 2011. Hydrogeology and WIPP Compliance. Waste Management Symposia, Phoenix, AZ, Waste Management Conference 2011, paper 11658 (paper and oral presentation).
• Kuhlman, K.L. & B. Malama, 2010. Computing the Electrokinetic Response with Simple Models via Eigenvalue Decomposition. American Geophysical Union, San Francisco, CA, Fall Meeting 2010, abstract H13D-0992 (poster).
• Ferré, T.P.A, M.S. Mirjat, D.A. Rose, M. Tuller & K.L. Kuhlman, 2010. Optimizing Flood Irrigation to Flush Accumulated Salts Through Zonal Flooding. American Society of Agronomy/Crop Science Society of America/Soil Science Society of America, Long Beach, CA, joint International Annual 2010 meeting (poster, and code).
• Malama, B., K.L. Kuhlman & A. Revil, 2009. Aquifer Characterization using Transient Streaming Potentials Generated by Flow During Pumping Tests – New developments. American Geophysical Union, San Francisco, CA, Fall Meeting 2009, abstract H43C-1046 (poster).
• Hillesheim, M.B., K.L. Kuhlman & R.L. Beauheim, 2009. Significant Development in the Understanding of Culebra Hydrology at the WIPP Site. Transactions of the American Nuclear Society, Atlanta, GA, Volume 100, p. 122–124 (oral presentation and extended abstract).
• Kuhlman, K.L. & S.P. Neuman, 2008. Particle Tracking in Transient Groundwater Flow Fields with the Laplace Transform Analytic Element Method. American Geophysical Union, San Francisco, CA, Fall Meeting 2008, abstract H31F-0949 (poster).
• Kuhlman, K.L. & S.P. Neuman, 2007. Transient Analytic Element Solutions for Flexible Aquifer Test Analyses. American Geophysical Union, San Francisco, CA, Fall Meeting 2007, abstract H23I-08 (oral presentation).
• Malama, B., K.L. Kuhlman & W. Barrash, 2007. Extension of Leakage Theory to Unconfined Aquifer Flow. American Geophysical Union, Acapulco, Mexico, Spring Meeting 2007, abstract H53E-04 (poster).
• Kuhlman, K.L. & S.P. Neuman, 2006. Recent Advances in Laplace Transform Analytic Element Method (LT-AEM) Theory and Application to Transient Groundwater Flow. American Geophysical Union, San Francisco, CA, Fall Meeting 2006, abstract H41B-0397 (poster).
• Kuhlman, K.L. & S.P. Neuman, 2006. Recent Advances in LT-AEM Theory and Application to Transient Groundwater Flow. Copenhagen, Denmark, Conference on Computational Methods in Water Resources XVI (paper and oral presentation; download LT-AEM code).

Conference Session Chairing

• Kuhlman, K.L., P.K. Mishra & M. Hilpert, Recent Advances in Hydrogeology: Innovative Solutions to Single and Multi-phase Flow and Transport Issues, American Geophysical Union, San Francisco, CA, Fall Meeting 2011; two oral sessions (H33J, H34B) and one poster session (H31D).
• Bridge J.W., C.B. Graham, K.L. Kuhlman & H. Vereecken, High-Resolution Hydrogeophysical Characterization of Soils and Aquifers From Microscale to Field Scale, American Geophysical Union, San Francisco, CA, Fall Meeting 2010, oral session H21K.

Computer Codes

Codes are free for use and redistribution via the MIT license; direct any comments or problems to me (contact info at top of the page). I will try my best to help or accommodate you. Most of the codes are scripts or un-compiled source code with a Linux-style makefile. If you cannot compile or run the code yourself, I may be able to help you compile it or set up the right environment to get it working.

For most of the computer codes below, the files are available both as a zip archive for easy download (ZIP) and as a directory for browsing (DIR). The codes under more active development have read-only links to my Mercurial distributed version control system repository (DVCS).

• (DVCS) · Laplace Transform Analytic Element Method
  A Fortran03 program that implements the LT-AEM for circular (including wells as a special case) and elliptical elements (including lines as a special case), used in Bakker & Kuhlman (2011), my dissertation, and Kuhlman & Neuman (2009). This code is a continual work in progress, but it is functional and useful. This Fortran code includes an implementation of the same modified Mathieu library also given as a stand-alone Python library below.
• (DVCS) ·Unconfined well-test simulator
  A Fortran03 program that implements the major unconfined well test solutions (Neuman, 1972+1974; Moench, 1995+2001; Mishra & Neuman, 2010+2011; Malama, 2011), and various special degenerate cases (Theis, 1935; Hantush, 1961). The code executes in parallel on multiple processors using OpenMP. It can compute a time-series solution at a point (including the derivative) or a contour map of drawdown in space at a given time. The software is designed to be easily used with common plotting and parameter estimation codes.
• (ZIP) (DIR) (DVCS) · Moving water table unconfined slug-test solution
  A Fortran90 program that implements the unconfined (MWT solution of Neuman 1972) slug test solution that accounts for linearized momentum balance in the slug test interval (i.e., oscillating slug responses) discussed in Malama et al. (2011). This program computes the double numerical inverse Laplace and Hankel transforms in extended precision to compute the time-domain solution given in the paper. A makefile and source code are currently included (email me if you are interested in this solution but cannot build it yourself).
  
  NB: The extended or unified Hyder solution from Malama et al. (2011) is a simple MATLAB script that is different, but also available. If interested, please contact me or the corresponding author from that paper.
• (ZIP) (DIR) · Leaky-unconfined aquifer flow solution
  A Fortran90 program for computing the leaky-unconfined solutions discussed in Malama, Kuhlman & Barrash (2007; 2008). This program does the double numerical inverse Laplace and Hankel transforms required to compute the time-domain solutions given in the papers. A Windows binary and fairly complete documentation is included.
• (ZIP) (DIR) (DVCS) · Electrokinetic pumping test response solution
  A Fortran90 program for computing the electrokinetic response due to pumping a well in an unconfined system, as discussed in Malama et al. (2009a; 2009b). The Stehfest algorithm is used for the numerical Laplace inverse transform, while a combination of tanh-sinh quadrature and accelerated Gauss-Lobatto quadrature (between the zeros of the J₀ Bessel function) is used for the numerical Hankel inverse transform. These algorithms are much faster and more accurate than the algorithms used in the leaky-unconfined papers listed above.
• (ZIP) (DIR) · Unsaturated flow from an elliptical pipe
  A set of MATLAB scripts for computing Quasilinear infiltration solutions from Kuhlman & Warrick (2008). These scripts compute the required ratios of Mathieu functions, compute the solution, and plot the figures shown in the paper.
• (ZIP) (DIR) · Modified Mathieu functions of complex Mathieu parameter
  A Python module for computing both angular and radial modified Mathieu functions (and their derivatives with respect to argument) of integer order and general complex Mathieu parameter (Re(q)<0), see a pdf summary of Mathieu function library output, and a numerical comparison to a published C++ Mathieu function library for real q (Alhargan, 2000). My Python module requires numpy and scipy. This same functionality is also implemented in Fortran in my LT-AEM code available above.
• (ZIP) (DIR) · Cokriging hydraulic heads and boundary conditions
  A set of MATLAB scripts for cokriging heads taking boundary conditions into account, without requiring the user to explicitly come up with the cross-variograms, since they are given explicitly by the physics of the problem (Kuhlman & Pardo-Igúzquiza, 2010). These scripts set up and solve the cokriging equations using either the true derivative or finite-difference approximations, and can make all the figures and examples given in the paper.
• (ZIP) (PDF) · Scrabble rhyming word lists
  A rhyming dictionary, where words are sorted alphabetically, starting at the last letter of the word, working back towards the front of the word. These are useful, for example, when you are trying to think of all the legal Scrabble words that that end in “–uppy” or “–house”, etc. This is not a true rhyming dictionary, as words that sound alike, but are spelled differently are not put together; this is the sort of list that would really only be useful for Scrabble players. The Python code used to generate the lists from the standard Scrabble word lists, and the Python scripts used to create the LaTeX, that are then used to generate the pdf (e.g., see 11-letter word list), are included in the zip file.
• (DIR) · 2D Steady-State Finite-Difference Solution to Richards' Equation
  A MATLAB script modified and slightly improved from an Excel-spreadsheet developed by Ty Ferré for his HWR-505 vadose zone hydrology class. It is not highly optimized code, but it is many times faster than the spreadsheet version. The code is vectorized, with no loops except for iteration.