### Early Groundwater Model (T)

 Early Groundwater ModelBy Darrel Dunn Ph.D., PG (Consulting hydrogeologist.  Professional Synopsis)The purpose of this web page is to place an early finite-difference groundwater modeling experiment on the World Wide Web.  The value of this experiment is only historical.  The modeling was performed in the mid-1960's and finally published in my University of Illinois Ph.D. Thesis (138) in 1967.  As far as I know the model was the first ever attempt to calibrate a groundwater model to actual water level data.  This modeling occurred because Walter Rose, my Petroleum Reservoir Engineering professor, suggested that the method cold be applied to groundwater reservoirs.  Previously, it had been applied to petroleum reservoirs.  Consequently, I studied the application to petroleum reservoirs and researched ways of obtaining solutions to large sets of finite-difference equations.  I concluded that the simplest approach would be Gauss-Seidel iteration, which was presented in a text (139) used in a FORTRAN course that I audited.  When I used this method in my thesis project, I applied extrapolation to increase the rate of convergence.  The Gauss-Seidel method with extrapolation is now called successive over relaxation (SOR).My Ph.D. thesis involved the hydrogeology of an area around Stettler, Alberta, Canada.  Stettler produced its water from wells scattered around the town.  The water came from an inhomogeneous aquifer.  Consequently, I had an opportunity to use a finite-difference groundwater model to study the wellfield.  The following excerpts from my thesis describe the model and the results.  Click the links.Title page and abstractDescription of groundwater model and results.FORTRAN code.Modern groundwater models are much more complex.  Modern computers can handle more computationally intensive code without utilizing excessive CPU time.  Also, the development of code is much easier because one no longer has to hand a punch-card deck to a computer technician and wait hours for the results each time the program is submitted.  There were no PCs, only mainframes.AddendumAfter being awarded my Ph.D., I completed many projects involving ground water modeling, surface water modeling, and other hydrogeologic and geologic tasks.  I have used my own computer codes, MODFLOW, SWIFTIII, MIKE SHE/MIKE 11, AEM and other hydrologic and geologic software.If you need a consulting hydrogeologist to perform a groundwater modeling task, email ddunn@dunnhydrogeo.com.