Lake Washington is a large freshwater lake adjacent to the city of Seattle
and the largest in King County
. It is a ribbon lake, 35 km long and surface area of approximately 88 km2
. Mercer Island
lies at the southern end of the lake. The main inflows are from the Sammamish River
in the north and Cedar River
in the south. The outflow is to via a ship canal at Puget Sound in the west with discharge of approximately 7 m3
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 application of the SGZ model.
This tutorial document will guide you how to setup Sigma Zed model by using the EFDC_Explorer (EE). It will cover 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 us first introduce about the main form of EE User Interface in order to better understand our explanation hereafter. Figure 1 is the main form of EFDC_Explorer or EE User Interface. Functioning for individual icons are described as following;
Figure 1 EFDC Explorer Main Form.
2 Import Grid
This session will guide you to import the grid into EFDC_Explorer. With a complicated grid such as this the grid generation software CVLGrid has been used. Lake Washington in Washington state, the USA will be chosen as an example of building a 3D Lake Model with Sigma Zed in EE.
The gird generation process includes following steps:
- Open EE
- Click Generate New Model icon as on the main menu of EE interface. Then Generate EFDC Model frame appears shown in Figure 2.
- Select CVLGrid in the Grid Type. The user click Browse button to select grid file name as "LW Grid.cvl" as shown in Figure 2. Note that EE also supports importing a variety of grid formats with option Import Grid shown in Figure 3.
Figure 2 Generate EFDC Model form.
Figure 3 Import grid options.
4. Click Generate button and finish. A dialog will pop up to show the gird information (see Figure 4).
Figure 4 Newly created grid information.
5. Save the model by select this button Figure 5.
and create a new directory as shown in
Figure 5 New model saved.
3 Assigning the Initial Conditions
This section will guide you how to assign the initial conditions such as the bathymetry, water level and bottom roughness.
Figure 6 Assigning the Initial Conditions.
3.1 Assigning the Initial Bottom Conditions
- Select the Domain/Initial Conditions & Bottom Roughness tab and click the Assign button. A form will displayed as shown in Figure 7.
- in the Data File to text box browse to the bathymetry file XXXXX. This bathymetry file is simply a general x,y, z format.
- In this case, we choose Modify Options is Interpolate Data in cell and Interpolate Data meaning that it will take the surround data points to interpolate for the cells where there is no data.
- Note that Poly File is the area to assign the bathymetry data. There are few modify options for users to assign the data.
- Click the Apply button to take the effect before hitting the Done button.
Figure 7 Assigning model bathymetry.
3.2 Assigning the Depth/Water Surface Elevations
The next step is to assign the initial depth or water surface elevations. There are two options for setting the surface water elevation that are Use Constant and Use Point Measurements/Gridded Data. In this case we will use the former option.
- Click Assign button, select Use Constant: to assign a flat water surface elevation. Enter "6.5" as the number enter in the Operator or Constant box as shown in Figure 8.
- Click Apply button then click Done button to finish.
Figure 8 Assigning water surface elevation.
3.3 Assigning the Bottom Roughness (Z0)
- Click the Assign button in the Bottom Roughness (Z0) box (Figure 6).
- Check Use Constant and enter the roughness value to 0.02.
- Click the Apply button before hitting the Done button. (Figure 9)
Figure 9 Assigning bottom roughness.
4 Assigning the Boundary Conditions
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.
4.1 Preparing the Flow Boundary.
- Select the Domain/Boundary Conditions. (See Figure 11).
- Click to the E button Figure 12) which is next to Flow to edit the flow boundary. (
- Entering the Number of Series into the box (in this case, enter 7)
- Give a Tittle for associated time series.
- Copy and Paste the time series data into the workspace. (See Figure 13 ).
Figure 11 Assigning Flow Boundary Conditions.
Figure 12 Editing the Boundary Time Series.
6. Click to the Current button to view the current time series. If there are a number of layers then check Sum Layers to show total flow. (See Figure 13).
Figure 13 Flow Time Series Plot.
7. Change up/downward this
button to edit other time series.
8. Click OK to finish editing the boundary time series.
4.2 Preparing Temperature Boundary.
- Select the Domain/Boundary Conditions. (See Figure 14).
- Click to the E buttonFigure 14)which is next to Temperature to edit the flow boundary. (
- Enter the Number of Series (Type 3) (See Figure 15)
- Give a Tittle for associated time series.
- Copy and Paste the time series data into the workspace. (See Figure 15 ).
Figure 14 Assigning Temperature Boundary Conditions.
Figure 15 Editing the Boundary Time Series.
6. Click to the Current button to view the current time series. (See Figure 16).
Figure 16 Editing the Boundary Time Series.
4.2 Preparing Wind Boundary.
- Select the Domain/Boundary Conditions. (See Figure 17 ).
- Click to the E button which is next to Winds to edit the boundary. (See Figure 17)
- Enter the Number of Series (Type 1) (See Figure 18)
- Give a Tittle for associated time series.
- Copy and Paste the time series data into the workspace. (See Figure 18).
- The user can edit parameters of wind station by clicking Show Parameters (See Figure 19)
- the user can view wind rose by clicking Wind Rose button (See Figure 20)
Figure 17 Assigning Winds Boundary Conditions.
Figure 18 Editing the Boundary Time Series.
Figure 19 Editing Wind Station Parameters.
Figure 20 Wind Rose.
4.3 Preparing Atmospheric Boundary.
- Select the Domain/Boundary Conditions.
- Click to the E button which is next to Atmospheric to edit the boundary. (See Figure 21)
- Enter the Number of Series (Type 1) (See Figure 22)
- Give a Tittle for associated time series.
- Copy and Paste the time series data into the workspace. (See Figure 22).
- The user can edit parameters of ATM station by clicking Show Parameters (See Figure 23)
- the user can view timeseries of atmospheric data by clicking Current button (See Figure 24)
Figure 21 Assigning Atmospheric Boundary.
Figure 22 Editing the Boundary Time Series.
Figure 23 Editing ATM Station Parameters.
Figure 24 Viewing ATM Data.
4.4 Assigning Time Series to the Boundary Location Cells.
When all required boundary time series are prepared. You have to assign those boundary time series into the model cells.
4.4.1 Assigning flow boundary
In order to assign the flow boundary, the following steps should be taken
1. Click to the 2D Planview icon Figure 1 ).
on the main form (See
2. Choose Boundary C’s in the Viewing Opt’s
3. Check Enable Edit and Show Grid (See 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 "Display Options" in the top menu of 2D ViewPlan then go to "Annotations", next 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 Right-Mouse-Click on the inflow/outflow location cell/ choose New (See Figure 28).
6. Enter the boundary group ID: Inflow group (See Figure 29 ).
7. Select boundary types. It is dependent on your current boundary type to choose the suitable boundary type. In this case, we have 1 flow boundary so we choose number 1 (See Figure 30).
8. Select the associated with this inflow boundary time series. (See Figure 31). then click OK to complete.
Figure 28 Right-Mouse-Click on the inflow cell.
Figure 29 Enter Boundary Group ID.
Figure 30 Select the Boundary Types.
Figure 31 Assign the Corresponding Time Series.
9. The boundary cells might have multiple cells to present the real river width. In order to assign the next cell as inflow cell, you need to come back to step 5 and Right-mouse Click to that cell and choose Add to Adjacent. The inflow is now divided to the number of assigned cells. (See Figure 32).
Figure 32 Assign the more boundary cells.
4.3.2 Assigning temperature boundary
Temperature boundary associated with flow boundary, in this case there two temperature boundary, one is associated with Cedar River inflow and the other is related to Sammamish River inflow. The following steps should be taken:
- Click to the 2D ViewPlan icon on the main form (See Figure 1).
- Choose Boundary C’s in the Viewing Opt’s .
- Enable Edit grid by checking to
- Right-mouse Click on the inflow location cell/ choose Edit (See Figure 33).
- Select temperature timeseries corresponding to inflow boundary (ID), for example temperature table 0831 belongs to Cedar River Inflow (See Figure 34).
- Click OK button to finish.
Figure 33 Right-Mouse-Click on the inflow cell.
Figure 34 Assign Temperature Boundary.
5 Setup Grid Layers (Sigma Zed)
- In the EE main form, click to Domain Tab then click Grid (See Figure 35).
- Choose SGZ: Specified Bot Layer.
- Enter the number of water layer. In this case # of Layers is 55 then press enter button on the keyboard (See Figure 35).
- Click Set SGZ Layering, the form will appear as shown in Figure 36.
- Put KMin = 2 then click OK button.
- Cells information will be updated as shown in Figure 37.
Figure 35 Assign Temperature Boundary.
Figure 36 SGZ Layering Options Form.
Figure 37 SGZ Layering Options Information.
6 Activate Modules
When the user click Activate Modules tab, a list of modules will be displayed for selecting. Check on box of Activate Temperature as shown in Figure 38. After that the Temperature tab will be turned on (See Figure 38). Click Temperature tab, a form will appear as shown in Figure 39
Click Assign button to assign initial condition for temperature. In the appeared form, the user set values as shown in Figure 40 then click Apply and Done button to finish.
Figure 38 Activate Modules.
Figure 39 Temperature Module Form.
Figure 40 Assigning Initial Temperature Form.
Figure 41 Surface Heat Exchange Settings.
Figure 42 Bed Heat & Ice Options Settings.
7 Model Timing
After above sessions, you are almost having a hydrodynamic model. This part will guide you how to setup the model simulation time and model time steps.
- Step 1: Select Timing/ Linkage and Model Run Timing (See Figure 43)
- Enter Duration of starting/ ending the simulation. Note that the boundaries time series should be always covered this simulation duration period. Otherwise the model will not run.
Figure 43 Model Run Time.
Table 2 Model Run Time Explanation.
Time of Start (days)
Julian starting date (an automate conversion to Gregorian date is there)
# Reference Periods
Total simulation time (an automate conversion to Gregorian date is there)
Duration of Reference Period (hours)
Time Step (second)
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 ramp-up
If >0 then it is an additional criteria to determine the dynamic time step.
The base date of all data and simulation period.
3. Select the EFDC_Explorer Linkage to set the EFDC Results to EFDC_Explorer Frequency. 60 minutes mean that the EE will store the output in every 60 minute for displaying the model results in the EE. (See Figure 44). Note that, smaller output frequency will cause larger output file.
Figure 44 Setting Linkage Output Frequency.
8 Hydrodynamic Model Setup
This session will guide you how to set the hydrodynamic model. Since the EFDC model is applied the Wet and Dry condition to optimize the simulation time. Thus, we should set for this condition as following:
- Step 1: Select Hydrodynamics/ Wetting & Drying box
- Step 2: Set Flag is equal to -99.
- Step 3: Entering the Wet/Dry Depth. Remember that the wet depth should always greater than the Dry depth. (Figure 45).
- The user can go to the Modify button to adjust the calibration hydraulic parameters there (Figure 46).
- Save the model project.
Figure 45 Hydrodynamic Model Setup.
Figure 46 HMD Modify Form.
9 Running EFDC
- Select the Setting icon on the main form to browse to the EFDC Executable file. (Figure 47).
Figure 47 Browse to the EFDC Executable File.
2. Step 2: Select the Run EFDC icon to on the main form and click the Run EFDC_DSI button to run the model (Figure 48).
Figure 48 Run EFDC Setting.
If everything are setting well, the model will start running and you will see the MS-DOS Window appear to shown the model results as see in Figure 49. Note that you can hit any characters on the key-broad to pause the simulation and check the model results. If you want to exit the simulation hit the same key, if you want to continue run then hit any other key.
Figure 49 Running EFDC Window.
10 View the Model Calibration Plots
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 Figure 51 then click OK button to finish.
After that click Plots button, a form of plot generation options appears for the user (See Figure 52). if the user check on two boxes, the EE will automatically generate plots and ASCII data file and they are stored in #calib_plots folder. The user can stop the process by press Esc button on the keyboard during automatic generation.
Otherwise the EE generate plot one by one.
Time Series Comparison and Vertical Profile Comparisons plots shown in Figure 53 and 54.
Figure 50 Model Calibration Window.
Figure 51 Time Series Comparison Form.
Figure 52 Calibration Plot Generation Options.
Figure 53 Time Series Comparison Plot.
Figure 54 Vertical Profile Comparison Plot.