The bathymetry of Lake Washington shows that it is a deep, narrow, glacial trough with steeply sloping sides and approximately 65 m deep at its deepest point. These morphologic features are highly suitable for the application of the SGZ model.
This tutorial document will guide you on how to set up a Sigma Zed model by using the EFDC+ Explorer (EE). It will cover the preparation of the necessary input files for the EFDC model and visualization of the output by using the EFDC+ Explorer (EE) Software.
The data used for this tutorial are from Lake Washington. All files for this tutorial are found in Lake Washington model downloadable from the EE website.
Before going to each session, let’s first introduce the main form of EE User Interface in order to better understand our explanation hereafter. Figure 1 is the main form of EFDC+ Exploreror EE User Interface. Functioning for individual icons are described as following;
Figure 1. EFDC+ Explorer Main Form.
This session will guide you to import the grid into EFDC+ Explorer. With a complicated grid such as this, the grid generation software CVLGrid is required to been used. Lake Washington in Washington state, the USA has been chosen as an example of building a 3D Lake Model with Sigma Zed in EE.
The grid generation process includes the following steps:
Figure 2. Generate EFDC Model form.
Figure 3. Import grid options.
4. Click OK button, the imported grid is shown (Figure 4).
Figure 4. Newly imported grid.
5. Save the model by selecting this button and create a new directory as shown in Figure 5.
Figure 5. New model saved.
This section will guide you on how to assign the initial conditions such as the bathymetry, water level, and bottom roughness.
Figure 6. Assigning the Initial Conditions.
Figure 7. Assigning model bathymetry.
The next step is to assign the initial depth or water surface elevations. There are also two options for setting the surface water elevation that is Use Constant and Use Scatter (XYZ) data. In this case, we will use the former option.
Figure 8. Assigning water surface elevation.
Figure 9. Assigning bottom roughness.
This next step is to prepare for the boundary conditions and assign these to the model grid. In this model, there are seven flow boundaries, all but one of which are rivers flowing into Lake Washington. The Lock BC is an outflow. Figure 10 shows flow boundaries of the model.
Figure 10. Inflow and outflow of Lake Washington.
Figure 11. Assigning Flow Boundary Conditions.
3. Enter the Number of Series into the box. There are seven flow boundaries as mentioned so it should be “7”.
4. Give a Series Name for associated time series (remember to press Enter after each input).
5. Select Import Data from File button and then browse to the inflow data file as shown in Figure 12.
6. Click Preview/Graph to view the current time series (Figure 12).
Figure 12. Editing the Boundary Time Series.
Figure 13. Flow Time Series Plot.
7. Change up/downward this button to edit other time series.
8. Click OK to finish editing the flow boundary time series.
Figure 14. Enable Temperature module.
3. Enter the Number of Series into the box. There are three temperature boundaries as mentioned so it should be “3”.
4. Give a Series Name for associated time series (remember to press Enter after each input).
5. Copy and paste time series data into the workspace corresponding to each series. Figure 12 shows time series of Cedar River temperature.
6. Go to the Time series plot menu and click on View series to view the current time series (Figure 12). For a case where there are multiple layers, please click on View Option at below to choose the way to analyze multiple layers (Sum layer for total flow, Average layer for average flow or Custom for specific layers).
Figure 15. Editing the Boundary Time Series.
Figure 16. Temperature Time Series plot.
Figure 17. Assigning Winds Boundary Conditions.
Figure 18. Editing the Boundary Time Series.
Figure 19. Editing Wind Station Parameters.
Figure 20. Wind Rose.
Figure 21. Assigning Atmospheric Boundary.
Figure 22. Editing the Boundary Time Series.
Figure 23. Editing ATM Station Parameters.
Figure 24. Viewing ATM Data.
When all required boundary time series are prepared the user must assign those boundary time series to the model cells.
In order to assign the flow boundary, the following steps should be taken:
1. Click to the 2DH View menu item or icon on the main form (Figure 1).
2. Choose Boundaries in the View Layer Control by clicking on the light icon .
3. Enable Edit grid by turning on the icon (Figure 25).
4. In order to know locations of cells assigned flow BC, the user should load the labels file (BC Location.dat). Go to Import an External Overlay Layer button at the bottom Layer Control from then select the label file and remember to choose the type of import file as Label Files (*.lbl, *.dat, *.txt), then load the label file as shown in Figure 26 and Figure 27.
Figure 25. Assigning Boundary Condition Cells.
Figure 26. Loading Label File.
Figure 27. Labels Displayed
5. Zoom in to each label location then RMC on the inflow/outflow location cell and click on New (Figure 28).
6. Enter the boundary group ID: Inflow group (Figure 29).
7. Select boundary types. It is dependent on your current boundary condition to choose the suitable boundary type. In this case, we choose Flow Boundary (Figure 29).
8. Select the associated with this inflow boundary time series (Figure 30) then click OK to complete.
Figure 28. Right-Mouse-Click on the inflow cell.
Figure 29. Enter Boundary Group Name and Select the Boundary Types.
Figure 30. Assign the Corresponding Time Series.
9. The boundary cells often have multiple cells to represent the real river width. In order to assign the next cell as an inflow cell, return to step 5 and RMC that cell and choose Add Cell to Adjacent Boundary Group. The inflow is now divided across the number of assigned cells (Figure 31).
Figure 31. Assign more boundary cells.
10. Select all boundary cells by pressing the Shift key and clicking on all boundary cells (3 cells in this case), then RMC on one of them, and select Edit Boundary Cells (Figure 32).
Figure 32. Right-Mouse-Click on the inflow boundary cells.
11. Click on Dist Factors to divide the flow across the 3 cells (See Figure 33) and press OK to finish.
Figure 33. Distribute all inflow boundary cells of the Cedar River group.
12. Carry these same steps above for the remaining flow boundaries.
The temperature boundary is associated with the flow boundary, in this case there two temperature boundaries, one is associated with Cedar River inflow and the other is related to Sammamish River inflow. The following steps should be taken:
Figure 34. Assign temperature boundary.
Figure 35. Open Model grid windows.
Figure 36. SGZ Layering Options Form.
Figure 37. SGZ Layering Options Information.
RMC on Temperature menu item in the Modules section and click on Settings, to open the Temperature Parameters form as shown in Figure 39. Set the initial conditions for each tab as shown in the following figures:
Figure 38. Open Temperature module.
Figure 39. General Settings.
Figure 40. Surface Heat Exchange Settings.
Figure 41. Initial Conditions Settings.
Figure 42. Boundary Conditions Settings.
After these, you are almost completed building the hydrodynamic model. This section will guide you on how to set up the model simulation time and model time steps.
Figure 43. Model Run Time.
Table 2. Model Run Time Explanation.
Name | Explanation |
Time of Start (days) | Julian starting date (an automated conversion to Gregorian date is there) |
# Reference Periods | Total simulation time (an automated conversion to Gregorian date is there) |
Duration of Reference Period (hours) | Reference period |
Time Step (second) | Delta T |
Safety Factor | 0<Safety Factor < 1 to active the Dynamic time step |
# Ramp-Up Loops | Number of initial interaction to hold the time step to a constant during the ramp-up |
Maximum dH/dT | If >0 then it is an additional criterion to determine the dynamic time step. |
Beginning Date/Time | The base date of all data and simulation period. |
3. RMC on Linkage tab in Timing/Linkage section, the EFDC Model Linkages form will be displayed as shown in Figure 44.
Select the EFDC+ Explorer Linkage tab to set the Linkage Output Frequency. Setting this to 60 minutes means that EFDC will write the output every 60 minutes for displaying the model results in the EE (Figure 44). Note that a smaller output frequency will cause a larger output file. In this case, we will set the frequency equal to 30 min.
Figure 44. Setting Linkage Output Frequency.
This session will guide you on how to set the hydrodynamic model. The EFDC model applies a wetting and drying condition. Thus, we should set this condition as follows:
Figure 45. Open Hydrodynamics settings.
Figure 46. Hydrodynamic Options form.
Figure 47. Open EFDC+ Run Options windows.
2. In this Window set the Number of OMP Threads to a number less than or equal to half the Max. Then browse to the EFDC Executable file (see Figure 48).
3. Click the Run EFDC+ button to run the model (Figure 48).
Figure 48. Run EFDC Settings.
If everything is set correctly, the model will start running and you will see the MS-DOS Window appear to display the model results as shown in Figure 49. Note that you can press any characters on the key-broad to pause the simulation and check the model results by using the Refresh button. If you want to exit the simulation select the same key, if you want to continue run then select any other key.
Figure 49 Running EFDC Window.
Go to Model Analysis Tab, select Model Calibration as shown in Figure 50. Click Define/Edit button to fill the Time Series Comparison form as shown in Figure 51 then click OK button to finish.
Then click the Plots button, a form for Calibration Plot Generation is displayed (Figure 52). If the user check on the two checkboxes, the EE will automatically generate plots and ASCII data file which are stored in #calib_plots folder. The user can stop the process by press the Escape button on the keyboard during automatic generation. Otherwise, the EE generates a plot one by one.
Time-series comparison and vertical profile comparison plots are shown in Figures 53 and 54.
Figure 50. Model Calibration form.
Figure 51. Time Series Comparisons form.
Figure 52. Calibration Plot Generation Options.
Figure 53. Time series comparison plot.
Figure 54. Vertical profile comparison plot.