STANMOD
Criterion | Explanation |
General Description | Analytical solution to the subsurface convective-diffusion equation for solute transport |
Model Domain | Soil and groundwater |
Developer | United States Department of Agriculture (USDA) |
Hardware computing requirements | For use on Windows machines |
Code language | All computational programs are written in FORTRAN, and the graphical interface is in MS Visual C++. |
Original application | A Windows-based software package for simulating solute transport in porous media using analytical solutions of the convection-dispersion equation. The suite of analytical models includes models for one-dimensional and multi-dimensional transport. |
Public/proprietary and cost | Public; No cost |
Physically or empirically based | Physically based. |
Mathematical methods used | STANMOD includes several models: The 3DADE model solves the direct problem (i.e., the concentration is calculated as a function of time and space for specified model parameters), and the indirect (inverse) problem in which the program estimates selected parameters by fitting one of the analytical solutions to specified experimental data. In the N3DADE code, analytical solutions for three-dimensional equilibrium solute transport in the subsurface pertain to selected cases of three-dimensional solute transport during steady, unidirectional water flow in porous media having uniform flow properties.
STNAMOD uses the analytical solutions to the one-dimensional convective dispersion equation described in Toride et al (1993). |
Input data requirements | User creates input data through the Project Manager module. New projects are given a name and assigned to a Workspace (any existing, accessible subdirectory). Input data requirements include groundwater flow related parameters (hydraulic conductivity, storativity), and solute transport related parameters (dispersitivity, porosity, initial pore water concentration, adsorption-related and decay- and production-related parameters). |
Outputs | The post-processing unit consists of simple x-y plots for graphical presentation of the results and a dialog window that displays an ASCII output file. |
Pre-processing and post-processing tools | ASCII text outputs can easily be brought into Excel. |
Representation of uncertainty | The model does not have built-in uncertainty representation. This can be assessed for each specific case using sensitivity analysis. |
Prevalence | Widely used for studying vadose zone flow and transport processes, including for agricultural application. STANMOD has used in the Delta to simulate DOC transport in Twitchell Island cores (Deverel et al. 2017). |
Ease of use for public entities | Readily available and easy to use |
Ease of obtaining information and availability of technical support | Support for problems with the model code, or suggestions for improvement can be submitted to: |
Source code availability | Source code is not readily available. The executable file is available at: https://www.ars.usda.gov/research/software/download/?softwareid=102&modecode=20-36-05-00 |
Status of model development | Version 2.0 completed for use in 2000 |
Challenges for integration | STANMOD is a one-dimensional model that is limited in its ability to simulate transient flow conditions. It was previously used to simulate DOC transport in Delta organic-soil column laboratory experiments. |
References
Toride, N., Leu, F.J, and Van Genuchten, M.T., 1993, A comprehensive set of analytical solutions for non-equilibrium solute transport with first order decay and zero-order production. Water Resources Research, 29, 2167-2182.
Deverel, S. J, Leighton, D. A, Lucero, C., and Ingrum, T., 2017, Simulation of Subsidence Mitigation Effects on Island Drain Flow, Seepage, and Organic Carbon Loads on Subsided Islands Sacramento–San Joaquin Delta. San Francisco Estuary and Watershed Science, 15(4). Retrieved from https://escholarship.org/uc/item/4q34019.
Simunek, J., Van Genuchten, M.T., Sejna, M. Toride, N. and Leij, F. J., 1999, The STANMOD Computer Software for Evaluating Solute Transport in Porous Media Using Analytical Solutions of Convection-Dispersion Equation, U. S. Salinity Laboratory, Agricultural Research Service, U. S. Department of Agriculture, Riverside, California.