CE-QUAL-W2

Criterion	Explanation
General Description	CE-QUAL-W2 is a water quality and hydrodynamic model in 2D (longitudinal-vertical) for rivers, estuaries, lakes, reservoirs, and river basin systems. W2 models basic eutrophic processes such as temperature, nutrients, algae, dissolved oxygen, organic matter, and sediment. The model also simulate fish habitat, algae, epiphyton/periphyton, zooplankton, macrophyte, CBOD, sediment diagenesis, generic water quality groups, internal dynamic pipe/culvert model, and hydraulic structures algorithms.
Model Domain	The model domain is flexible, specified by user.
Developer	U.S. Army Corps of Engineers (USACE), Portland State University
Hardware computing requirements	The minimum configuration is an 80386 PC equipped with a math coprocessor. A minimum of four megabytes of memory is needed unless the user has an operation system or extender that uses virtual memory. A hard disk with a minimum available space of 25 Mb is also required. In version 2.0, most of the computations are now performed using single precision (32 bits) but double precision is still needed for some computations.
Code language	The executables for the preprocessor and the model were compiled using Intel Fortran XE 17. The W2Control GUI was compiled using Visual Basic 6.
Original application	For modeling reservoirs, examples including DeGray Reservoir, Spokane River, Spokane River, Columbia Slough estuary, sediment diagenesis in a reservoir, and particle tracking in a reservoir.
Public/proprietary and cost	The model is in the public domain. The model release includes executables, source codes and examples for using the model.
Physically or empirically based	Physically based
Mathematical methods used	The governing equations are a mass and a momentum balance of fluid phase in a control volume. The resulting equations are the continuity and the conservation of momentum equations. The continuity equation integrated over the depth from the water surface to the bottom is called the free water surface equation.
Input data requirements	Geometry, bathymetry, inflow/water quality from boundaries/tributaries, meteorological data
Outputs	Water balance, water level, time series concentrations of conservative and non-conservative constituents, water quality over depth profile.
Pre-processing and post-processing tools	There is a stand-alone V4 GUI preprocessor as part of the download package. The W2ControlGUI is GUI preprocessor used in setting up the control file for the model. There is a post-processor for W2 model output developed by Dynamic Solutions-International, LLC (DSI), Inc. group and an excel macro utility that aids the model user in writing out files compatible with CE-QUAL-W2. W2Tools is the W2 post-processor by DSI.
Representation of uncertainty	None specified.
Prevalence	>2,000 applications worldwide in different countries
Ease of use for public entities	The model requires knowledge and experience in water quality modeling in water bodies. The model release package includes examples for using the model and the preprocessor.
Ease of obtaining information and availability of technical support	The model release includes executables, source codes, and examples for using the model and preprocessor. Model documentation/manual is available for download. There is a user forum for discussing modeling issues and blog on model updates and changes to the code.
Source code availability	The model release includes the source code.
Status of model development	Current model releases is Version 4.1 (09/27/2018).
Challenges in integration	The model provides inputs and outputs in text files. Model outputs of hydrodynamic and water quality can be integrated with other models.

References

Cole, TM, and Wells, SA. 2015. "CE-QUAL-W2: A two-dimensional, laterally averaged, hydrodynamic and water quality model, version 3.72," Department of Civil and Environmental Engineering, Portland State University, Portland, OR.

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