CXTFIT

Metadata Updated: February 21, 2020

Successful predictions of the fate and transport of solutes in the subsurface hinges on the availability of accurate transport parameters. We modified and updated the CXTFIT (version 1.0) code of Parker and van Genuchten [1984] for estimating solute transport parameters using a nonlinear least-squares parameter optimization method. The program may be used to solve the inverse problem by fitting mathematical solutions of theoretical transport models, based upon the convection-dispersion equation (CDE), to experimental results. This approach allows parameters in the transport models to be quantified. The program may also be used to solve the direct or forward problem to determine the concentration as a function of time and/or position. Three different one-dimensional transport models are included: the conventional CDE; the chemical and physical nonequilibrium CDE; and a stochastic stream tube model based upon the local-scale CDE with equilibrium or nonequilibrium adsorption. The two independent stochastic parameters in the stream-tube model are the pore-water velocity, v, and either the dispersion coefficient, D, the distribution coefficient, Kd, or the nonequilibrium rate parameter, alpha. These pairs of stochastic parameters were described with a bivariate lognormal probability density function (pdf). Examples are given on how transport parameters may be determined from laboratory or field tracer experiments for several types of initial and boundary conditions, as well as different zero-order production profiles. The program comes with a user manual giving a detailed description of the computer program, including the subroutines used to evaluate the analytical solutions for optimizing model parameters. Input and output files for all major problems are also included in the manual.

Access & Use Information

Public: This dataset is intended for public access and use. License: Creative Commons CCZero

Downloads & Resources

Dates

Metadata Created Date February 21, 2020
Metadata Updated Date February 21, 2020

Metadata Source

Harvested from USDA JSON

Additional Metadata

Resource Type Dataset
Metadata Created Date February 21, 2020
Metadata Updated Date February 21, 2020
Publisher Agricultural Research Service
Unique Identifier ac900b5a-51a0-434b-b574-ae8e2c6996fc
Maintainer
Skaggs, Todd
Maintainer Email
Public Access Level public
Bureau Code 005:18
Metadata Context https://project-open-data.cio.gov/v1.1/schema/catalog.jsonld
Schema Version https://project-open-data.cio.gov/v1.1/schema
Catalog Describedby https://project-open-data.cio.gov/v1.1/schema/catalog.json
Harvest Object Id 1be2f804-0ffc-4f44-bfd9-15b27e80be5d
Harvest Source Id 50ca39af-9ddb-466d-8cf3-84d67a204346
Harvest Source Title USDA JSON
License https://creativecommons.org/publicdomain/zero/1.0/
Data Last Modified 2019-08-05
Program Code 005:040
Source Datajson Identifier True
Source Hash 589f7d043bd02b7ac0c72f48a91fd313533e9c20
Source Schema Version 1.1

Didn't find what you're looking for? Suggest a dataset here.