CE‐QUAL‐W2 is a two‐dimensional (2D), longitudinal/vertical, hydrodynamics and water quality model. It enables characterization of the vertical and longitudinal changes in a reservoir. The model assumes the reservoir is “well mixed” laterally, with no variation from one side of the channel to the other in a given layer (vertical) and segment (longitudinal). Since CE-QUAL-W2 assumes lateral homogeneity, it is especially suited for relatively long and narrow waterbodies that exhibit longitudinal and vertical water quality gradients.
The CE-QUAL-W2 model incorporates the following water quality considerations: Longitudinal-vertical hydrodynamics and water quality in stratified and non-stratified systems, nutrients-dissolved oxygen-organic matter interactions, fish habitat, selective withdrawal from stratified reservoir outlets, hypolimnetic aeration, multiple algae, epiphyton/periphyton, zooplankton, macrophyte, CBOD, sediment diagenesis model, and generic water quality groups, internal dynamic pipe/culvert model, and hydraulic structures (weirs, spillways) algorithms. The hydraulic structures algorithms include submerged and two-way flow over submerged hydraulic structures as well as a dynamic shading algorithm based on topographic and vegetative cover.
CE-QUAL-W2 includes variable density as affected by temperature, salinity, Total Dissolved Solids (TDS), and Total Suspended Solids (TSS) to simulate stratified flow. There are 28 water quality constituent state variables, and any combination of constituents can be included or excluded from a simulation. The effects of salinity or total dissolved solids/salinity on density, and thus hydrodynamics, are included only when simulated in the water quality module. The water quality algorithm is modular, allowing constituents to be easily added as additional subroutines.
CE-QUAL-W2 has been applied to rivers, lakes, reservoirs, estuaries, and combinations thereof. CE-QUAL-W2 supports the Corps’ high priority need for environmental assessment, restoration, and management. CE-QUAL-W2 provides flow and water quality information to help improve management of critical downstream habitat. CE-QUAL-W2 is very widely used by USACE and other federal, state, and local agencies, e.g., USGS, USBR, State of California for environmental impact assessments, planning studies, etc. CE-QUAL-W2 was first released by ERDC in 1986. Since that time, more than 1,100 model applications have been developed worldwide for reservoirs, rivers, estuaries, and other water bodies. It is also used as a research tool by researchers at universities and other organizations. At least 1,500 publications utilized or cited CE-QUAL-W2 in the year 2022 alone.
Key features of CE-QUAL-W2:
- Longitudinal-vertical hydrodynamics and water quality in stratified and non-stratified systems
- Interactions between nutrients, dissolved oxygen, and organic matter
- Fish habitat volume
- Selective withdrawal from specially design outlets to provide cold-water releases from stratified reservoirs
- Hypolimnetic aeration
- Multiple algae, epiphyton/periphyton, zooplankton, and macrophyte groups
- Carbonaceous Biochemical Oxygen Demand (CBOD)
- Sediment diagenesis model
- Generic water quality groups
- Internal dynamic pipe/culvert model
- Hydraulic structures (weirs, spillways) algorithms
- The hydraulic structures algorithms include submerged and two-way flow over submerged hydraulic structures as well as a dynamic shading algorithm based on topographic and vegetative cover.
- Variable density as affected by temperature, salinity, Total Dissolved Solids (TDS), and Total Suspended Solids (TSS) to simulate stratified flow
- 28 water quality constituent state variables:
- Any combination of constituents can be included or excluded from a simulation.
- The effects of salinity or total dissolved solids/salinity on density, and thus hydrodynamics, are included only when simulated in the water quality module.
- The water quality algorithm is modular, allowing constituents to be easily added as additional subroutines.
The current release version of CE-QUAL-W2 is Version 4.5 (as of August 2023).
Keywords:
CE-QUAL-W2, water quality, hydrodynamics, reservoirs, rivers, lakes, estuaries, temperature, dissolved oxygen, nutrients, algae, harmful algal blooms, sediment oxygen demand, organic matter, sediment diagenesis, salinity, transport, 2D
The CE-QUAL-W2 modeling software is available for use by academic and government researchers at no charge.
The CE-QUAL-W2 source code is maintained within a version control repository on GitHub.
The executables for CE-QUAL-W2 and its supporting utility programs is compiled and maintained for the Microsoft Window’s operating system. There are plans to develop and maintain versions for MacOS and Linux in future years. The executables are available on ACEIT computers via standard download.
- The CE-QUAL-W2 GitHub site, https://github.com/EcohydrologyTeam/CE-QUAL-W2, contains the following information:
- User’s manual: https://github.com/EcohydrologyTeam/CE-QUAL-W2/tree/main/documentation/model
- Auto-port selection methodology: https://github.com/EcohydrologyTeam/CE-QUAL-W2/tree/main/documentation/USGS
- User’ guide for post-processing tools: https://github.com/EcohydrologyTeam/CE-QUAL-W2/tree/main/documentation/W2tools%20post-processor
- User’s guide for the Control File Converter utility program: https://github.com/EcohydrologyTeam/CE-QUAL-W2/tree/main/documentation/control%20file%20converter
- Example models: https://github.com/EcohydrologyTeam/CE-QUAL-W2/tree/main/examples
- Executable programs: https://github.com/EcohydrologyTeam/CE-QUAL-W2/tree/main/executables
- Source code: https://github.com/EcohydrologyTeam/CE-QUAL-W2/tree/main/presentations
- The materials for the three-day Aug 2023 CE-QUAL-W2 training course is available at the following GitHub site: https://github.com/EcohydrologyTeam/CE-QUAL-W2-Workshop-2022
- Recent Journal Publications
- Bornstein, Yoav, Ben Dayan, Amir Cahn, Scott Wells, and Mashor Housh (2022). Environmental Decision Support Systems as a Service: Demonstration on CE-QUAL-W2 Model. Water, 14(6). https://doi.org/10.3390/w14060885
- Dutta, Ranojit Kumar, and Baishakhi Das (2020). Modeling Curtain Weirs for Controlling Algal Blooms in the Largest Tributary of the Three Gorges Reservoir, China. Alexandria Engineering Journal, 59(1), 323–332. https://doi.org/10.1016/j.aej.2019.12.044
- Lei Zhao, Sihang Cheng, Yanxin Sun, Rui Zou, Wenjing Ma, Qichao Zhou, and Yong Liu (2021). Thermal mixing of Lake Erhai (Southwest China) induced by bottom heat transfer: Evidence based on observations and CE-QUAL-W2 model simulations. Journal of Hydrology, 603(Part B), 126973. https://doi.org/10.1016/j.jhydrol.2021.126973
- Lian, Jijian, Ye Yao, Chao Ma, and Qizhong Guo (2014). Reservoir Operation Rules for Controlling Algal Blooms in a Tributary to the Impoundment of Three Gorges Dam. Water, 6(10), 3200–3223. https://doi.org/10.3390/w6103200
- Mateus, Marcos, Ricardo Vieira, Carina Almeida, Miguel Silva, and Filipa Reis (2018). ScoRE—A Simple Approach to Select a Water Quality Model. Water, 10(1811). https://doi.org/10.3390/w10121811
- Roohollah Noori, Hund-Der Yeh, Khosro Ashrafi, Najmeh Rezazadeh, Sayed M. Bateni, Abdulreza Karbassi, Fatemeh Torabi Kachoosangi, and Saber Moazami (2015). A reduced-order based CE-QUAL-W2 model for simulation of nitrate concentration in dam reservoirs, Journal of Hydrology, 530, 645-656. https://doi.org/10.1016/j.jhydrol.2015.10.022
- Saadatpour, Motahareh (2020). An Adaptive Surrogate Assisted CE-QUAL-W2 Model Embedded in Hybrid NSGA-II AMOSA Algorithm for Reservoir Water Quality and Quantity Management. Water Resources Management, 34(4), 1437–51. https://doi.org/10.1007/s11269-020-02510-x
- Saadatpour, Motahareh, Abbas Afshar, and John Eric Edinger (2017). Meta-Model Assisted 2D Hydrodynamic and Thermal Simulation Model (CE-QUAL-W2) in Deriving Optimal Reservoir Operational Strategy in Selective Withdrawal Scheme. Water Resources Management, 31(9), 2729–44. https://doi.org/10.1007/s11269-017-1658-x
- Shabani, Afshin, Xiaodong, Zhang, and Mike Ell (2017). Modeling Water Quantity and Sulfate Concentrations in the Devils Lake Watershed Using Coupled SWAT and CE-QUAL-W2. Journal of the American Water Resources Association, 53(4), 748-760. https://doi.org/10.1111/1752-1688.12535
- Zhang, Chen, Michael T. Brett, Shannon K. Brattebo, and Eugene B. Welch. (2018) How Well Does the Mechanistic Water Quality Model CE-QUAL-W2 Represent Biogeochemical Responses to Climatic and Hydrologic Forcing? Water Resources Research, 54(9), 2018WR022580. https://doi.org/10.1029/2018WR022580
- Zhang, Zhonglong, Bowen Sun, and Billy E. Johnson (2015). Integration of a benthic sediment diagenesis module into the two dimensional hydrodynamic and water quality model – CE-QUAL-W2. Ecological Modelling, 297, 213-231. https://doi.org/10.1016/j.ecolmodel.2014.10.025
The CE-QUAL-W2 development team (ERDC and PSU) has developed a suite eight models intended to verify and validate the numerical code integrity. The included suite of tests has been developed to test changes to the CE-QUAL-W2 model and ensure solutions are consistent across releases. This suite will be run every time a change is made to the model code. The new code must pass all tests before the code will be allowed to be integrated into the upstream repository of the CE-QUAL-W2 code. The test cases are available via public access at GitHub: https://github.com/EcohydrologyTeam/CE-QUAL-W2-dev/tree/main/testing. Descriptions of the different test cases are available on the GitHub site along with instructions for running them. These test cases also can serve as instructional examples of different ADCIRC model parameter settings.
Version 4.5 of CE-QUAL-W2 contains many new features and enhancements. A stand-alone V4 GUI preprocessor is included as part of the download package. A post-processor for W2 model output has been used since the V3.7 model by the DSI, Inc. group, and an Excel macro utility aids the model user in writing out files compatible with CE-QUAL-W2.
V4.5 includes many new features and upgrades and is not file compatible with earlier versions because of many new variables in the control file. Differences between versions are shown in Part 5 of the User’s Manual. The new model includes the following features, developed by Portland State University, with support by ERDC Environmental Laboratory and Portland District of U.S. Army Corps of Engineers for the development of many of these enhancements):
- Atmospheric deposition of any state variable - model user provides mass loading to waterbodies. There is now no need to specify a flow, temperature, and concentration file since only a time series of mass per area per time is used as an input.
- Ability to specify directly output of flow balance file, N and P mass balance file, water level file
- New generic constituent source: sediment release
- New state variables: water age, N2, dissolved total gas pressure, bacteria, CH4, Fe(II), FeOOH, Mn(II), MnO2, H2S. Many of these before were only operative using sediment diagenesis as generic constituents or were recommended generic constituents.
- New derived variables: turbidity (correlated to TSS), Secchi disk (based on light extinction), un-ionized ammonia (based on temperature, pH, and total ammonia), and Total Dissolved Gas (TDG).
- Ammonia volatilization is computed based on unionized ammonia volatilization rate and is a derived variable. pH must also be active as a derived variable.
- Implementation of variable algal settling velocity including buoyancy effects from Overman (2019). This allows for predicting the variable velocity of cyanobacteria allowing for rise and fall of the cells during the day and night.
- Zooplankton settling is a new zooplankton parameter.
- Implementation of algal toxin production based on Garstecki (2021)
- Ability to generate lake contours easily (elevation vs time for temperature and dissolved oxygen)
- Ability to generate river contours easily (model segment or distance along river vs time) for temperature and dissolved oxygen)
- The C groups dissolved organic C (DOC) and particulate organic C (POC) with both labile and refractory groups were added as an alternative to organic matter groups. The option is available to use either C or organic matter. This was done earlier by Dr. Zhonglong Zhang in an earlier version of W2.
- Sediment diagenesis updates. Many updates were made allowing for multiple vertical layers, simplified calculation, and much faster computation than before. Now when sediment diagenesis is turned ON, both zero order and first order sediment models are turned OFF internally. Also, the sediment diagenesis input file format has been updated and integrated into the Excel master sheet. This work was performed by Dr. Zhonglong Zhang at PSU.
- Removed internal minimum reaeration coefficient value and allowed model user to set a minimum value if required. For example, for waterbodies designated as "LAKE" with zero wind, the model will now predict zero reaeration unless a minimum value is set. The reaeration coefficient for the surface layer is now an output in the Time Series file.
- Updates to auto-port selection
- SYSTDG input files updated to CSV input format.
- Updates to particle settling and P adsorption onto inorganic SS. A bug was fixed where dissolved oxygen-controlled P adsorption to particles rather than just P adsorption to Fe.
- All external control files are included in an Excel master sheet for ease of writing out as CSV files.