WMS:CE-QUAL-W2

Creating and Running a CE-QUAL-W2 Model using WMS

WMS is a very effective aid for setting up the CE-QUAL-W2 bathymetry and control files.

In order to create the bathymetry file, the user will need to create a TIN representing the bottom elevations of the reservoir. This can be created from contour maps, depth soundings, or digital contours in CAD format. The accuracy of the TIN is very crucial to calibration of the model.

The created TIN is opened in WMS under the map module mode. A new CE-QUAL-W2 simulation should be started before editing any of the TIN. To edit the TIN the user must create a branch coverage and then trace an outline of the water body using the create feature arc tool. The user then can divide the water body into separate branches according to his/her discretion.

Next, the branch coverage is duplicated and renamed as segment coverage. Segments are created using the create feature arc tool according to the user’s discretion.

From here the user appropriately numbers the segments and branches. A tool is available that automatically numbers segments. Segment length and orientation is done using a tool designed for measuring distances. Then the user can create a storage-capacity curve. Options exist for plotting this curve as well as exporting the data that create this curve so that the user may compare it to an existing storage-capacity curve. In many instances the generated storage capacity curve will not match well with a given storage capacity curve. In this case the TIN will need to be calibrated to match the given storage capacity curve. Refer to Calibrating the TIN to match a given storage capacity curve and Verification of Bathymetric Data for more instructions. Finally, layers are created and widths calculated to complete the bathymetry creation process. For a more detailed description of setting up a bathymetry file the user should refer to Creating a CE-QUAL-W2 bathymetry file from a TIN.

If the user requires the WMS generated storage capacity curve to be very accurate when compared to a given storage capacity curve then it is recommended that the user create only one branch and segment to begin with in WMS. This makes generating a storage capacity curve simpler and faster. Once a reasonable storage capacity curve is created the user should then proceed to make a detailed bathymetry representation of the model.

With a completed bathymetry file the user can proceed to begin editing the control file. In the Job Control dialog the user can edit all of the fields that are needed for the W2 control file (job control dialog help file). Most of these values should be left at their defaults (if there are default values) unless the user has knowledge or experience that would dictate he/she do otherwise. Saving the simulation will produce the control file and bathymetry file.

Other input files will be needed to run a CE-QUAL model. WMS supports the creating and editing of some input files; however, it is recommended that the user employ a spreadsheet in the creation of these files because of the simplicity and speed of a spreadsheet for editing and formatting of text. Following is a list of the required files for a basic simulation (adding constituents, tributaries, precipitation, etc will require more input files to be created):

• Meteorological file
• Inflow file
• Outflow file
• Inflow temperature file
• Wind Sheltering file
• Shading file
• Bathymetry file
• Control file

It should be remembered that there is variation between every simulation and every user. All input files need to be spaced correctly or errors will prevent the program from running. Also, because of the vast amount of information it is possible that some information may be forgotten or misplaced. The best check for accurateness of the simulation is to run the preprocessor before running the actual model. This can help identify problems in the control file and other files. These errors and/or warnings are output to an error and/or warning file. After there are no further errors identified by the preprocessor the actual program should be run. Other errors may still exist that will prevent the program from running. These may be output to an error file and identified. If not then it is recommended that the user compare his/her simulation to any examples or known working simulations. This is a tedious way of isolating the problem, but it provides an opportunity to “get familiar” with the system, especially for new users. If none of this works there is a forum that can be used to contact the developers or ask questions of other users (http://www.cee.pdx.edu/w2/).

Processing the results can be done using many tools. A spreadsheet is a common tool and there are post processors available that simplify the process. A future update of WMS will contain post-processing features.

In most cases the user will be required to do some amount of calibration for the model to resemble observed data. The first calibration that should be performed is a water balance. The user should then look at calibrating the temperature. After a thermal calibration has been reached the user should then proceed to calibrate any constituents that are modeled. For help on calibration the user should refer to the CE-QUAL-W2 user’s manual[1] as well as looking at other published reports on models done using CE-QUAL-W2.

Grid Z-Magnification

Note that it may be necessary to change the Z-magnification in the WMS Display Options dialog to better visualize the CE-QUAL-W2 grids. The Z-magnification controls the height of the grid display in the WMS graphics window.

Related Topics

• CE-QUAL-W2 Branches
• CE-QUAL-W2 Layer Editor
• CE-QUAL-W2 Menu