Model:OTEQ

OTEQ

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Also known as
Model type	Single
Model part of larger framework
Note on status model
Date note status model

Incorporated models or components:

Spatial dimensions	1D
Spatial extent	Reach-Scale, Watershed-Scale
Model domain	Terrestrial, Hydrology
One-line model description	One-Dimensional Transport with Equilibrium Chemistry (OTEQ): A Reactive Transport Model for Streams and Rivers
Extended model description	One-Dimensional Transport with Equilibrium Chemistry (OTEQ): A Reactive Transport Model for Streams and Rivers OTEQ is a mathematical simulation model used to characterize the fate and transport of waterborne solutes in streams and rivers. The model is formed by coupling a solute transport model with a chemical equilibrium submodel. The solute transport model is based on OTIS, a model that considers the physical processes of advection, dispersion, lateral inflow, and transient storage. The equilibrium submodel is based on MINTEQ, a model that considers the speciation and complexation of aqueous species, acid-base reactions, precipitation/dissolution, and sorption. Within OTEQ, reactions in the water column may result in the formation of solid phases (precipitates and sorbed species) that are subject to downstream transport and settling processes. Solid phases on the streambed may also interact with the water column through dissolution and sorption/desorption reactions. Consideration of both mobile (waterborne) and immobile (streambed) solid phases requires a unique set of governing differential equations and solution techniques that are developed herein. The partial differential equations describing physical transport and the algebraic equations describing chemical equilibria are coupled using the sequential iteration approach. The model's ability to simulate pH, precipitation/dissolution, and pH-dependent sorption provides a means of evaluating the complex interactions between instream chemistry and hydrologic transport at the field scale. OTEQ is generally applicable to solutes which undergo reactions that are sufficiently fast relative to hydrologic processes ("Local Equilibrium"). Although the definition of "sufficiently fast" is highly solute and application dependent, many reactions involving inorganic solutes quickly reach a state of chemical equilibrium. Given a state of chemical equilibrium, inorganic solutes may be modeled using OTEQ's equilibrium approach. This equilibrium approach is facilitated through the use of an existing database that describes chemical equilibria for a wide range of inorganic solutes. In addition, solute reactions not included in the existing database may be added by defining the appropriate mass-action equations and the associated equilibrium constants. As such, OTEQ provides a general framework for the modeling of solutes under the assumption of chemical equilibrium. Despite this generality, most OTEQ applications to date have focused on the transport of metals in streams and small rivers. The OTEQ documentation is therefore focused on metal transport. Potential model users should note, however, that additional applications are possible.

Keywords:	biogeochemistry, water quality,

Name	Rob Runkel
Type of contact	Model developer
Institute / Organization	USGS
Postal address 1
Postal address 2
Town / City	Boulder
Postal code	80303
State	Colorado
Country	United States
Email address	runkel@usgs.gov
Phone
Fax

Supported platforms	Unix, Linux
Other platform
Programming language	Fortran77
Other program language
Code optimized	Single Processor
Multiple processors implemented
Nr of distributed processors
Nr of shared processors
Start year development	1991
Does model development still take place?	Yes
If above answer is no, provide end year model development
Code development status	Only maintenance
When did you indicate the 'code development status'?	2020
Model availability	As code
Source code availability (Or provide future intension)	Through web repository
Source web address	http://water.usgs.gov/software/OTEQ/
Source csdms web address
Program license type	Other
Program license type other	http://water.usgs.gov/software/help/notice/
Memory requirements
Typical run time

Describe input parameters	see user documentation
Input format	ASCII
Other input format
Describe output parameters	Solute concentrations as a function of space and time
Output format	ASCII
Other output format
Pre-processing software needed?	Yes
Describe pre-processing software	All I/O is done with flat ASCII files; The 'MINTEQ Input file' is created using the Proteq utility; remaining input files may be created using a text editor
Post-processing software needed?	Yes
Describe post-processing software	All I/O is done with flat ASCII files; Output files are first processed by a utility (posteq) -- resultant files can then be plotted with the user's own software.
Visualization software needed?	No
If above answer is yes
Other visualization software

Describe processes represented by the model	Physical transport: Advection, Dispersion, Inflow, Transient Storage, and Settling. Chemistry: Precipitation/Dissolution, Sorption/Desorption, Oxidation/Reduction, aqueous complexation, and acid-base reactions
Describe key physical parameters and equations	Partial differential equations describing mass transport (Advection-Dispersion-Reaction equations) and algebraic equations describing chemical equilibria are coupled using the Sequential Iteration Approach
Describe length scale and resolution constraints
Describe time scale and resolution constraints
Describe any numerical limitations and issues	see numerical aspects described in Section 4 of the documentation

Describe available calibration data sets	see user documentation; also see applications at http://water.usgs.gov/software/OTEQ/apps/
Upload calibration data sets if available:
Describe available test data sets	see user documentation; also see applications at http://water.usgs.gov/software/OTEQ/apps/
Upload test data sets if available:
Describe ideal data for testing

Do you have current or future plans for collaborating with other researchers?

Is there a manual available?	Yes
Upload manual if available:	Media:TM6ChB6.pdf
Model website if any	http://water.usgs.gov/software/OTEQ/
Model forum / discussion board

Comments

This part will be filled out by CSDMS staff

OpenMI compliant	No but possible
BMI compliant	No but possible
WMT component	No but possible
PyMT component
Is this a data component

Can be coupled with:

Model info

Authors

Rob Runkel

Source code

Go to external source code site

Model citations

Nr. of publications:	2
Total citations:	137
h-index:	2
m-quotient:	0.07

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Introduction

History

References

Nr. of publications:	2
Total citations:	137
h-index:	2
m-quotient:	0.07

Featured publication(s)	Year	Model described	Type of Reference	Citations
Runkel, Robert L.; Bencala, Kenneth E.; Broshears, Robert E.; Chapra, Steven C.; 1996. Reactive Solute Transport in Streams: 1. Development of an Equilibrium-Based Model. Water Resources Research, 32, 409–418. 10.1029/95WR03106 (View/edit entry)	1996	OTEQ	Model overview	80
Runkel, Robert L.; McKnight, Diane M.; Bencala, Kenneth E.; Chapra, Steven C.; 1996. Reactive Solute Transport in Streams: 2. Simulation of a p H Modification Experiment. Water Resources Research, 32, 419–430. 10.1029/95WR03107 (View/edit entry)	1996	OTEQ	Model overview	58
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Issues

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Input Files

Output Files